1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Copyright (c) 2011, Joyent Inc. All rights reserved.
  25  * Copyright (c) 2011 Nexenta Systems, Inc. All rights reserved.
  26  * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  27  * Copyright 2014, OmniTI Computer Consulting, Inc. All rights reserved.
  28  */
  29 /* Copyright (c) 1990 Mentat Inc. */
  30 
  31 #include <sys/types.h>
  32 #include <sys/stream.h>
  33 #include <sys/strsun.h>
  34 #include <sys/strsubr.h>
  35 #include <sys/stropts.h>
  36 #include <sys/strlog.h>
  37 #define _SUN_TPI_VERSION 2
  38 #include <sys/tihdr.h>
  39 #include <sys/timod.h>
  40 #include <sys/ddi.h>
  41 #include <sys/sunddi.h>
  42 #include <sys/suntpi.h>
  43 #include <sys/xti_inet.h>
  44 #include <sys/cmn_err.h>
  45 #include <sys/debug.h>
  46 #include <sys/sdt.h>
  47 #include <sys/vtrace.h>
  48 #include <sys/kmem.h>
  49 #include <sys/ethernet.h>
  50 #include <sys/cpuvar.h>
  51 #include <sys/dlpi.h>
  52 #include <sys/pattr.h>
  53 #include <sys/policy.h>
  54 #include <sys/priv.h>
  55 #include <sys/zone.h>
  56 #include <sys/sunldi.h>
  57 
  58 #include <sys/errno.h>
  59 #include <sys/signal.h>
  60 #include <sys/socket.h>
  61 #include <sys/socketvar.h>
  62 #include <sys/sockio.h>
  63 #include <sys/isa_defs.h>
  64 #include <sys/md5.h>
  65 #include <sys/random.h>
  66 #include <sys/uio.h>
  67 #include <sys/systm.h>
  68 #include <netinet/in.h>
  69 #include <netinet/tcp.h>
  70 #include <netinet/ip6.h>
  71 #include <netinet/icmp6.h>
  72 #include <net/if.h>
  73 #include <net/route.h>
  74 #include <inet/ipsec_impl.h>
  75 
  76 #include <inet/common.h>
  77 #include <inet/ip.h>
  78 #include <inet/ip_impl.h>
  79 #include <inet/ip6.h>
  80 #include <inet/ip_ndp.h>
  81 #include <inet/proto_set.h>
  82 #include <inet/mib2.h>
  83 #include <inet/optcom.h>
  84 #include <inet/snmpcom.h>
  85 #include <inet/kstatcom.h>
  86 #include <inet/tcp.h>
  87 #include <inet/tcp_impl.h>
  88 #include <inet/tcp_cluster.h>
  89 #include <inet/udp_impl.h>
  90 #include <net/pfkeyv2.h>
  91 #include <inet/ipdrop.h>
  92 
  93 #include <inet/ipclassifier.h>
  94 #include <inet/ip_ire.h>
  95 #include <inet/ip_ftable.h>
  96 #include <inet/ip_if.h>
  97 #include <inet/ipp_common.h>
  98 #include <inet/ip_rts.h>
  99 #include <inet/ip_netinfo.h>
 100 #include <sys/squeue_impl.h>
 101 #include <sys/squeue.h>
 102 #include <sys/tsol/label.h>
 103 #include <sys/tsol/tnet.h>
 104 #include <rpc/pmap_prot.h>
 105 #include <sys/callo.h>
 106 
 107 /*
 108  * TCP Notes: aka FireEngine Phase I (PSARC 2002/433)
 109  *
 110  * (Read the detailed design doc in PSARC case directory)
 111  *
 112  * The entire tcp state is contained in tcp_t and conn_t structure
 113  * which are allocated in tandem using ipcl_conn_create() and passing
 114  * IPCL_TCPCONN as a flag. We use 'conn_ref' and 'conn_lock' to protect
 115  * the references on the tcp_t. The tcp_t structure is never compressed
 116  * and packets always land on the correct TCP perimeter from the time
 117  * eager is created till the time tcp_t dies (as such the old mentat
 118  * TCP global queue is not used for detached state and no IPSEC checking
 119  * is required). The global queue is still allocated to send out resets
 120  * for connection which have no listeners and IP directly calls
 121  * tcp_xmit_listeners_reset() which does any policy check.
 122  *
 123  * Protection and Synchronisation mechanism:
 124  *
 125  * The tcp data structure does not use any kind of lock for protecting
 126  * its state but instead uses 'squeues' for mutual exclusion from various
 127  * read and write side threads. To access a tcp member, the thread should
 128  * always be behind squeue (via squeue_enter with flags as SQ_FILL, SQ_PROCESS,
 129  * or SQ_NODRAIN). Since the squeues allow a direct function call, caller
 130  * can pass any tcp function having prototype of edesc_t as argument
 131  * (different from traditional STREAMs model where packets come in only
 132  * designated entry points). The list of functions that can be directly
 133  * called via squeue are listed before the usual function prototype.
 134  *
 135  * Referencing:
 136  *
 137  * TCP is MT-Hot and we use a reference based scheme to make sure that the
 138  * tcp structure doesn't disappear when its needed. When the application
 139  * creates an outgoing connection or accepts an incoming connection, we
 140  * start out with 2 references on 'conn_ref'. One for TCP and one for IP.
 141  * The IP reference is just a symbolic reference since ip_tcpclose()
 142  * looks at tcp structure after tcp_close_output() returns which could
 143  * have dropped the last TCP reference. So as long as the connection is
 144  * in attached state i.e. !TCP_IS_DETACHED, we have 2 references on the
 145  * conn_t. The classifier puts its own reference when the connection is
 146  * inserted in listen or connected hash. Anytime a thread needs to enter
 147  * the tcp connection perimeter, it retrieves the conn/tcp from q->ptr
 148  * on write side or by doing a classify on read side and then puts a
 149  * reference on the conn before doing squeue_enter/tryenter/fill. For
 150  * read side, the classifier itself puts the reference under fanout lock
 151  * to make sure that tcp can't disappear before it gets processed. The
 152  * squeue will drop this reference automatically so the called function
 153  * doesn't have to do a DEC_REF.
 154  *
 155  * Opening a new connection:
 156  *
 157  * The outgoing connection open is pretty simple. tcp_open() does the
 158  * work in creating the conn/tcp structure and initializing it. The
 159  * squeue assignment is done based on the CPU the application
 160  * is running on. So for outbound connections, processing is always done
 161  * on application CPU which might be different from the incoming CPU
 162  * being interrupted by the NIC. An optimal way would be to figure out
 163  * the NIC <-> CPU binding at listen time, and assign the outgoing
 164  * connection to the squeue attached to the CPU that will be interrupted
 165  * for incoming packets (we know the NIC based on the bind IP address).
 166  * This might seem like a problem if more data is going out but the
 167  * fact is that in most cases the transmit is ACK driven transmit where
 168  * the outgoing data normally sits on TCP's xmit queue waiting to be
 169  * transmitted.
 170  *
 171  * Accepting a connection:
 172  *
 173  * This is a more interesting case because of various races involved in
 174  * establishing a eager in its own perimeter. Read the meta comment on
 175  * top of tcp_input_listener(). But briefly, the squeue is picked by
 176  * ip_fanout based on the ring or the sender (if loopback).
 177  *
 178  * Closing a connection:
 179  *
 180  * The close is fairly straight forward. tcp_close() calls tcp_close_output()
 181  * via squeue to do the close and mark the tcp as detached if the connection
 182  * was in state TCPS_ESTABLISHED or greater. In the later case, TCP keep its
 183  * reference but tcp_close() drop IP's reference always. So if tcp was
 184  * not killed, it is sitting in time_wait list with 2 reference - 1 for TCP
 185  * and 1 because it is in classifier's connected hash. This is the condition
 186  * we use to determine that its OK to clean up the tcp outside of squeue
 187  * when time wait expires (check the ref under fanout and conn_lock and
 188  * if it is 2, remove it from fanout hash and kill it).
 189  *
 190  * Although close just drops the necessary references and marks the
 191  * tcp_detached state, tcp_close needs to know the tcp_detached has been
 192  * set (under squeue) before letting the STREAM go away (because a
 193  * inbound packet might attempt to go up the STREAM while the close
 194  * has happened and tcp_detached is not set). So a special lock and
 195  * flag is used along with a condition variable (tcp_closelock, tcp_closed,
 196  * and tcp_closecv) to signal tcp_close that tcp_close_out() has marked
 197  * tcp_detached.
 198  *
 199  * Special provisions and fast paths:
 200  *
 201  * We make special provisions for sockfs by marking tcp_issocket
 202  * whenever we have only sockfs on top of TCP. This allows us to skip
 203  * putting the tcp in acceptor hash since a sockfs listener can never
 204  * become acceptor and also avoid allocating a tcp_t for acceptor STREAM
 205  * since eager has already been allocated and the accept now happens
 206  * on acceptor STREAM. There is a big blob of comment on top of
 207  * tcp_input_listener explaining the new accept. When socket is POP'd,
 208  * sockfs sends us an ioctl to mark the fact and we go back to old
 209  * behaviour. Once tcp_issocket is unset, its never set for the
 210  * life of that connection.
 211  *
 212  * IPsec notes :
 213  *
 214  * Since a packet is always executed on the correct TCP perimeter
 215  * all IPsec processing is defered to IP including checking new
 216  * connections and setting IPSEC policies for new connection. The
 217  * only exception is tcp_xmit_listeners_reset() which is called
 218  * directly from IP and needs to policy check to see if TH_RST
 219  * can be sent out.
 220  */
 221 
 222 /*
 223  * Values for squeue switch:
 224  * 1: SQ_NODRAIN
 225  * 2: SQ_PROCESS
 226  * 3: SQ_FILL
 227  */
 228 int tcp_squeue_wput = 2;        /* /etc/systems */
 229 int tcp_squeue_flag;
 230 
 231 /*
 232  * To prevent memory hog, limit the number of entries in tcp_free_list
 233  * to 1% of available memory / number of cpus
 234  */
 235 uint_t tcp_free_list_max_cnt = 0;
 236 
 237 #define TIDUSZ  4096    /* transport interface data unit size */
 238 
 239 /*
 240  * Size of acceptor hash list.  It has to be a power of 2 for hashing.
 241  */
 242 #define TCP_ACCEPTOR_FANOUT_SIZE                512
 243 
 244 #ifdef  _ILP32
 245 #define TCP_ACCEPTOR_HASH(accid)                                        \
 246                 (((uint_t)(accid) >> 8) & (TCP_ACCEPTOR_FANOUT_SIZE - 1))
 247 #else
 248 #define TCP_ACCEPTOR_HASH(accid)                                        \
 249                 ((uint_t)(accid) & (TCP_ACCEPTOR_FANOUT_SIZE - 1))
 250 #endif  /* _ILP32 */
 251 
 252 /*
 253  * Minimum number of connections which can be created per listener.  Used
 254  * when the listener connection count is in effect.
 255  */
 256 static uint32_t tcp_min_conn_listener = 2;
 257 
 258 uint32_t tcp_early_abort = 30;
 259 
 260 /* TCP Timer control structure */
 261 typedef struct tcpt_s {
 262         pfv_t   tcpt_pfv;       /* The routine we are to call */
 263         tcp_t   *tcpt_tcp;      /* The parameter we are to pass in */
 264 } tcpt_t;
 265 
 266 /*
 267  * Functions called directly via squeue having a prototype of edesc_t.
 268  */
 269 void            tcp_input_data(void *arg, mblk_t *mp, void *arg2,
 270     ip_recv_attr_t *ira);
 271 static void     tcp_linger_interrupted(void *arg, mblk_t *mp, void *arg2,
 272     ip_recv_attr_t *dummy);
 273 
 274 
 275 /* Prototype for TCP functions */
 276 static void     tcp_random_init(void);
 277 int             tcp_random(void);
 278 static int      tcp_connect_ipv4(tcp_t *tcp, ipaddr_t *dstaddrp,
 279                     in_port_t dstport, uint_t srcid);
 280 static int      tcp_connect_ipv6(tcp_t *tcp, in6_addr_t *dstaddrp,
 281                     in_port_t dstport, uint32_t flowinfo,
 282                     uint_t srcid, uint32_t scope_id);
 283 static void     tcp_iss_init(tcp_t *tcp);
 284 static void     tcp_reinit(tcp_t *tcp);
 285 static void     tcp_reinit_values(tcp_t *tcp);
 286 
 287 static int      tcp_wsrv(queue_t *q);
 288 static void     tcp_update_lso(tcp_t *tcp, ip_xmit_attr_t *ixa);
 289 static void     tcp_update_zcopy(tcp_t *tcp);
 290 static void     tcp_notify(void *, ip_xmit_attr_t *, ixa_notify_type_t,
 291     ixa_notify_arg_t);
 292 static void     *tcp_stack_init(netstackid_t stackid, netstack_t *ns);
 293 static void     tcp_stack_fini(netstackid_t stackid, void *arg);
 294 
 295 static int      tcp_squeue_switch(int);
 296 
 297 static int      tcp_open(queue_t *, dev_t *, int, int, cred_t *, boolean_t);
 298 static int      tcp_openv4(queue_t *, dev_t *, int, int, cred_t *);
 299 static int      tcp_openv6(queue_t *, dev_t *, int, int, cred_t *);
 300 
 301 static void     tcp_squeue_add(squeue_t *);
 302 
 303 struct module_info tcp_rinfo =  {
 304         TCP_MOD_ID, TCP_MOD_NAME, 0, INFPSZ, TCP_RECV_HIWATER, TCP_RECV_LOWATER
 305 };
 306 
 307 static struct module_info tcp_winfo =  {
 308         TCP_MOD_ID, TCP_MOD_NAME, 0, INFPSZ, 127, 16
 309 };
 310 
 311 /*
 312  * Entry points for TCP as a device. The normal case which supports
 313  * the TCP functionality.
 314  * We have separate open functions for the /dev/tcp and /dev/tcp6 devices.
 315  */
 316 struct qinit tcp_rinitv4 = {
 317         NULL, tcp_rsrv, tcp_openv4, tcp_tpi_close, NULL, &tcp_rinfo
 318 };
 319 
 320 struct qinit tcp_rinitv6 = {
 321         NULL, tcp_rsrv, tcp_openv6, tcp_tpi_close, NULL, &tcp_rinfo
 322 };
 323 
 324 struct qinit tcp_winit = {
 325         tcp_wput, tcp_wsrv, NULL, NULL, NULL, &tcp_winfo
 326 };
 327 
 328 /* Initial entry point for TCP in socket mode. */
 329 struct qinit tcp_sock_winit = {
 330         tcp_wput_sock, tcp_wsrv, NULL, NULL, NULL, &tcp_winfo
 331 };
 332 
 333 /* TCP entry point during fallback */
 334 struct qinit tcp_fallback_sock_winit = {
 335         tcp_wput_fallback, NULL, NULL, NULL, NULL, &tcp_winfo
 336 };
 337 
 338 /*
 339  * Entry points for TCP as a acceptor STREAM opened by sockfs when doing
 340  * an accept. Avoid allocating data structures since eager has already
 341  * been created.
 342  */
 343 struct qinit tcp_acceptor_rinit = {
 344         NULL, tcp_rsrv, NULL, tcp_tpi_close_accept, NULL, &tcp_winfo
 345 };
 346 
 347 struct qinit tcp_acceptor_winit = {
 348         tcp_tpi_accept, NULL, NULL, NULL, NULL, &tcp_winfo
 349 };
 350 
 351 /* For AF_INET aka /dev/tcp */
 352 struct streamtab tcpinfov4 = {
 353         &tcp_rinitv4, &tcp_winit
 354 };
 355 
 356 /* For AF_INET6 aka /dev/tcp6 */
 357 struct streamtab tcpinfov6 = {
 358         &tcp_rinitv6, &tcp_winit
 359 };
 360 
 361 /*
 362  * Following assumes TPI alignment requirements stay along 32 bit
 363  * boundaries
 364  */
 365 #define ROUNDUP32(x) \
 366         (((x) + (sizeof (int32_t) - 1)) & ~(sizeof (int32_t) - 1))
 367 
 368 /* Template for response to info request. */
 369 struct T_info_ack tcp_g_t_info_ack = {
 370         T_INFO_ACK,             /* PRIM_type */
 371         0,                      /* TSDU_size */
 372         T_INFINITE,             /* ETSDU_size */
 373         T_INVALID,              /* CDATA_size */
 374         T_INVALID,              /* DDATA_size */
 375         sizeof (sin_t),         /* ADDR_size */
 376         0,                      /* OPT_size - not initialized here */
 377         TIDUSZ,                 /* TIDU_size */
 378         T_COTS_ORD,             /* SERV_type */
 379         TCPS_IDLE,              /* CURRENT_state */
 380         (XPG4_1|EXPINLINE)      /* PROVIDER_flag */
 381 };
 382 
 383 struct T_info_ack tcp_g_t_info_ack_v6 = {
 384         T_INFO_ACK,             /* PRIM_type */
 385         0,                      /* TSDU_size */
 386         T_INFINITE,             /* ETSDU_size */
 387         T_INVALID,              /* CDATA_size */
 388         T_INVALID,              /* DDATA_size */
 389         sizeof (sin6_t),        /* ADDR_size */
 390         0,                      /* OPT_size - not initialized here */
 391         TIDUSZ,         /* TIDU_size */
 392         T_COTS_ORD,             /* SERV_type */
 393         TCPS_IDLE,              /* CURRENT_state */
 394         (XPG4_1|EXPINLINE)      /* PROVIDER_flag */
 395 };
 396 
 397 /*
 398  * TCP tunables related declarations. Definitions are in tcp_tunables.c
 399  */
 400 extern mod_prop_info_t tcp_propinfo_tbl[];
 401 extern int tcp_propinfo_count;
 402 
 403 #define IS_VMLOANED_MBLK(mp) \
 404         (((mp)->b_datap->db_struioflag & STRUIO_ZC) != 0)
 405 
 406 uint32_t do_tcpzcopy = 1;               /* 0: disable, 1: enable, 2: force */
 407 
 408 /*
 409  * Forces all connections to obey the value of the tcps_maxpsz_multiplier
 410  * tunable settable via NDD.  Otherwise, the per-connection behavior is
 411  * determined dynamically during tcp_set_destination(), which is the default.
 412  */
 413 boolean_t tcp_static_maxpsz = B_FALSE;
 414 
 415 /*
 416  * If the receive buffer size is changed, this function is called to update
 417  * the upper socket layer on the new delayed receive wake up threshold.
 418  */
 419 static void
 420 tcp_set_recv_threshold(tcp_t *tcp, uint32_t new_rcvthresh)
 421 {
 422         uint32_t default_threshold = SOCKET_RECVHIWATER >> 3;
 423 
 424         if (IPCL_IS_NONSTR(tcp->tcp_connp)) {
 425                 conn_t *connp = tcp->tcp_connp;
 426                 struct sock_proto_props sopp;
 427 
 428                 /*
 429                  * only increase rcvthresh upto default_threshold
 430                  */
 431                 if (new_rcvthresh > default_threshold)
 432                         new_rcvthresh = default_threshold;
 433 
 434                 sopp.sopp_flags = SOCKOPT_RCVTHRESH;
 435                 sopp.sopp_rcvthresh = new_rcvthresh;
 436 
 437                 (*connp->conn_upcalls->su_set_proto_props)
 438                     (connp->conn_upper_handle, &sopp);
 439         }
 440 }
 441 
 442 /*
 443  * Figure out the value of window scale opton.  Note that the rwnd is
 444  * ASSUMED to be rounded up to the nearest MSS before the calculation.
 445  * We cannot find the scale value and then do a round up of tcp_rwnd
 446  * because the scale value may not be correct after that.
 447  *
 448  * Set the compiler flag to make this function inline.
 449  */
 450 void
 451 tcp_set_ws_value(tcp_t *tcp)
 452 {
 453         int i;
 454         uint32_t rwnd = tcp->tcp_rwnd;
 455 
 456         for (i = 0; rwnd > TCP_MAXWIN && i < TCP_MAX_WINSHIFT;
 457             i++, rwnd >>= 1)
 458                 ;
 459         tcp->tcp_rcv_ws = i;
 460 }
 461 
 462 /*
 463  * Remove cached/latched IPsec references.
 464  */
 465 void
 466 tcp_ipsec_cleanup(tcp_t *tcp)
 467 {
 468         conn_t          *connp = tcp->tcp_connp;
 469 
 470         ASSERT(connp->conn_flags & IPCL_TCPCONN);
 471 
 472         if (connp->conn_latch != NULL) {
 473                 IPLATCH_REFRELE(connp->conn_latch);
 474                 connp->conn_latch = NULL;
 475         }
 476         if (connp->conn_latch_in_policy != NULL) {
 477                 IPPOL_REFRELE(connp->conn_latch_in_policy);
 478                 connp->conn_latch_in_policy = NULL;
 479         }
 480         if (connp->conn_latch_in_action != NULL) {
 481                 IPACT_REFRELE(connp->conn_latch_in_action);
 482                 connp->conn_latch_in_action = NULL;
 483         }
 484         if (connp->conn_policy != NULL) {
 485                 IPPH_REFRELE(connp->conn_policy, connp->conn_netstack);
 486                 connp->conn_policy = NULL;
 487         }
 488 }
 489 
 490 /*
 491  * Cleaup before placing on free list.
 492  * Disassociate from the netstack/tcp_stack_t since the freelist
 493  * is per squeue and not per netstack.
 494  */
 495 void
 496 tcp_cleanup(tcp_t *tcp)
 497 {
 498         mblk_t          *mp;
 499         conn_t          *connp = tcp->tcp_connp;
 500         tcp_stack_t     *tcps = tcp->tcp_tcps;
 501         netstack_t      *ns = tcps->tcps_netstack;
 502         mblk_t          *tcp_rsrv_mp;
 503 
 504         tcp_bind_hash_remove(tcp);
 505 
 506         /* Cleanup that which needs the netstack first */
 507         tcp_ipsec_cleanup(tcp);
 508         ixa_cleanup(connp->conn_ixa);
 509 
 510         if (connp->conn_ht_iphc != NULL) {
 511                 kmem_free(connp->conn_ht_iphc, connp->conn_ht_iphc_allocated);
 512                 connp->conn_ht_iphc = NULL;
 513                 connp->conn_ht_iphc_allocated = 0;
 514                 connp->conn_ht_iphc_len = 0;
 515                 connp->conn_ht_ulp = NULL;
 516                 connp->conn_ht_ulp_len = 0;
 517                 tcp->tcp_ipha = NULL;
 518                 tcp->tcp_ip6h = NULL;
 519                 tcp->tcp_tcpha = NULL;
 520         }
 521 
 522         /* We clear any IP_OPTIONS and extension headers */
 523         ip_pkt_free(&connp->conn_xmit_ipp);
 524 
 525         tcp_free(tcp);
 526 
 527         /*
 528          * Since we will bzero the entire structure, we need to
 529          * remove it and reinsert it in global hash list. We
 530          * know the walkers can't get to this conn because we
 531          * had set CONDEMNED flag earlier and checked reference
 532          * under conn_lock so walker won't pick it and when we
 533          * go the ipcl_globalhash_remove() below, no walker
 534          * can get to it.
 535          */
 536         ipcl_globalhash_remove(connp);
 537 
 538         /* Save some state */
 539         mp = tcp->tcp_timercache;
 540 
 541         tcp_rsrv_mp = tcp->tcp_rsrv_mp;
 542 
 543         if (connp->conn_cred != NULL) {
 544                 crfree(connp->conn_cred);
 545                 connp->conn_cred = NULL;
 546         }
 547         ipcl_conn_cleanup(connp);
 548         connp->conn_flags = IPCL_TCPCONN;
 549 
 550         /*
 551          * Now it is safe to decrement the reference counts.
 552          * This might be the last reference on the netstack
 553          * in which case it will cause the freeing of the IP Instance.
 554          */
 555         connp->conn_netstack = NULL;
 556         connp->conn_ixa->ixa_ipst = NULL;
 557         netstack_rele(ns);
 558         ASSERT(tcps != NULL);
 559         tcp->tcp_tcps = NULL;
 560 
 561         bzero(tcp, sizeof (tcp_t));
 562 
 563         /* restore the state */
 564         tcp->tcp_timercache = mp;
 565 
 566         tcp->tcp_rsrv_mp = tcp_rsrv_mp;
 567 
 568         tcp->tcp_connp = connp;
 569 
 570         ASSERT(connp->conn_tcp == tcp);
 571         ASSERT(connp->conn_flags & IPCL_TCPCONN);
 572         connp->conn_state_flags = CONN_INCIPIENT;
 573         ASSERT(connp->conn_proto == IPPROTO_TCP);
 574         ASSERT(connp->conn_ref == 1);
 575 }
 576 
 577 /*
 578  * Adapt to the information, such as rtt and rtt_sd, provided from the
 579  * DCE and IRE maintained by IP.
 580  *
 581  * Checks for multicast and broadcast destination address.
 582  * Returns zero if ok; an errno on failure.
 583  *
 584  * Note that the MSS calculation here is based on the info given in
 585  * the DCE and IRE.  We do not do any calculation based on TCP options.  They
 586  * will be handled in tcp_input_data() when TCP knows which options to use.
 587  *
 588  * Note on how TCP gets its parameters for a connection.
 589  *
 590  * When a tcp_t structure is allocated, it gets all the default parameters.
 591  * In tcp_set_destination(), it gets those metric parameters, like rtt, rtt_sd,
 592  * spipe, rpipe, ... from the route metrics.  Route metric overrides the
 593  * default.
 594  *
 595  * An incoming SYN with a multicast or broadcast destination address is dropped
 596  * in ip_fanout_v4/v6.
 597  *
 598  * An incoming SYN with a multicast or broadcast source address is always
 599  * dropped in tcp_set_destination, since IPDF_ALLOW_MCBC is not set in
 600  * conn_connect.
 601  * The same logic in tcp_set_destination also serves to
 602  * reject an attempt to connect to a broadcast or multicast (destination)
 603  * address.
 604  */
 605 int
 606 tcp_set_destination(tcp_t *tcp)
 607 {
 608         uint32_t        mss_max;
 609         uint32_t        mss;
 610         boolean_t       tcp_detached = TCP_IS_DETACHED(tcp);
 611         conn_t          *connp = tcp->tcp_connp;
 612         tcp_stack_t     *tcps = tcp->tcp_tcps;
 613         iulp_t          uinfo;
 614         int             error;
 615         uint32_t        flags;
 616 
 617         flags = IPDF_LSO | IPDF_ZCOPY;
 618         /*
 619          * Make sure we have a dce for the destination to avoid dce_ident
 620          * contention for connected sockets.
 621          */
 622         flags |= IPDF_UNIQUE_DCE;
 623 
 624         if (!tcps->tcps_ignore_path_mtu)
 625                 connp->conn_ixa->ixa_flags |= IXAF_PMTU_DISCOVERY;
 626 
 627         /* Use conn_lock to satify ASSERT; tcp is already serialized */
 628         mutex_enter(&connp->conn_lock);
 629         error = conn_connect(connp, &uinfo, flags);
 630         mutex_exit(&connp->conn_lock);
 631         if (error != 0)
 632                 return (error);
 633 
 634         error = tcp_build_hdrs(tcp);
 635         if (error != 0)
 636                 return (error);
 637 
 638         tcp->tcp_localnet = uinfo.iulp_localnet;
 639 
 640         if (uinfo.iulp_rtt != 0) {
 641                 tcp->tcp_rtt_sa = MSEC2NSEC(uinfo.iulp_rtt);
 642                 tcp->tcp_rtt_sd = MSEC2NSEC(uinfo.iulp_rtt_sd);
 643                 tcp->tcp_rto = tcp_calculate_rto(tcp, tcps, 0);
 644         }
 645         if (uinfo.iulp_ssthresh != 0)
 646                 tcp->tcp_cwnd_ssthresh = uinfo.iulp_ssthresh;
 647         else
 648                 tcp->tcp_cwnd_ssthresh = TCP_MAX_LARGEWIN;
 649         if (uinfo.iulp_spipe > 0) {
 650                 connp->conn_sndbuf = MIN(uinfo.iulp_spipe,
 651                     tcps->tcps_max_buf);
 652                 if (tcps->tcps_snd_lowat_fraction != 0) {
 653                         connp->conn_sndlowat = connp->conn_sndbuf /
 654                             tcps->tcps_snd_lowat_fraction;
 655                 }
 656                 (void) tcp_maxpsz_set(tcp, B_TRUE);
 657         }
 658         /*
 659          * Note that up till now, acceptor always inherits receive
 660          * window from the listener.  But if there is a metrics
 661          * associated with a host, we should use that instead of
 662          * inheriting it from listener. Thus we need to pass this
 663          * info back to the caller.
 664          */
 665         if (uinfo.iulp_rpipe > 0) {
 666                 tcp->tcp_rwnd = MIN(uinfo.iulp_rpipe,
 667                     tcps->tcps_max_buf);
 668         }
 669 
 670         if (uinfo.iulp_rtomax > 0) {
 671                 tcp->tcp_second_timer_threshold =
 672                     uinfo.iulp_rtomax;
 673         }
 674 
 675         /*
 676          * Use the metric option settings, iulp_tstamp_ok and
 677          * iulp_wscale_ok, only for active open. What this means
 678          * is that if the other side uses timestamp or window
 679          * scale option, TCP will also use those options. That
 680          * is for passive open.  If the application sets a
 681          * large window, window scale is enabled regardless of
 682          * the value in iulp_wscale_ok.  This is the behavior
 683          * since 2.6.  So we keep it.
 684          * The only case left in passive open processing is the
 685          * check for SACK.
 686          * For ECN, it should probably be like SACK.  But the
 687          * current value is binary, so we treat it like the other
 688          * cases.  The metric only controls active open.For passive
 689          * open, the ndd param, tcp_ecn_permitted, controls the
 690          * behavior.
 691          */
 692         if (!tcp_detached) {
 693                 /*
 694                  * The if check means that the following can only
 695                  * be turned on by the metrics only IRE, but not off.
 696                  */
 697                 if (uinfo.iulp_tstamp_ok)
 698                         tcp->tcp_snd_ts_ok = B_TRUE;
 699                 if (uinfo.iulp_wscale_ok)
 700                         tcp->tcp_snd_ws_ok = B_TRUE;
 701                 if (uinfo.iulp_sack == 2)
 702                         tcp->tcp_snd_sack_ok = B_TRUE;
 703                 if (uinfo.iulp_ecn_ok)
 704                         tcp->tcp_ecn_ok = B_TRUE;
 705         } else {
 706                 /*
 707                  * Passive open.
 708                  *
 709                  * As above, the if check means that SACK can only be
 710                  * turned on by the metric only IRE.
 711                  */
 712                 if (uinfo.iulp_sack > 0) {
 713                         tcp->tcp_snd_sack_ok = B_TRUE;
 714                 }
 715         }
 716 
 717         /*
 718          * XXX Note that currently, iulp_mtu can be as small as 68
 719          * because of PMTUd.  So tcp_mss may go to negative if combined
 720          * length of all those options exceeds 28 bytes.  But because
 721          * of the tcp_mss_min check below, we may not have a problem if
 722          * tcp_mss_min is of a reasonable value.  The default is 1 so
 723          * the negative problem still exists.  And the check defeats PMTUd.
 724          * In fact, if PMTUd finds that the MSS should be smaller than
 725          * tcp_mss_min, TCP should turn off PMUTd and use the tcp_mss_min
 726          * value.
 727          *
 728          * We do not deal with that now.  All those problems related to
 729          * PMTUd will be fixed later.
 730          */
 731         ASSERT(uinfo.iulp_mtu != 0);
 732         mss = tcp->tcp_initial_pmtu = uinfo.iulp_mtu;
 733 
 734         /* Sanity check for MSS value. */
 735         if (connp->conn_ipversion == IPV4_VERSION)
 736                 mss_max = tcps->tcps_mss_max_ipv4;
 737         else
 738                 mss_max = tcps->tcps_mss_max_ipv6;
 739 
 740         if (tcp->tcp_ipsec_overhead == 0)
 741                 tcp->tcp_ipsec_overhead = conn_ipsec_length(connp);
 742 
 743         mss -= tcp->tcp_ipsec_overhead;
 744 
 745         if (mss < tcps->tcps_mss_min)
 746                 mss = tcps->tcps_mss_min;
 747         if (mss > mss_max)
 748                 mss = mss_max;
 749 
 750         /* Note that this is the maximum MSS, excluding all options. */
 751         tcp->tcp_mss = mss;
 752 
 753         /*
 754          * Update the tcp connection with LSO capability.
 755          */
 756         tcp_update_lso(tcp, connp->conn_ixa);
 757 
 758         /*
 759          * Initialize the ISS here now that we have the full connection ID.
 760          * The RFC 1948 method of initial sequence number generation requires
 761          * knowledge of the full connection ID before setting the ISS.
 762          */
 763         tcp_iss_init(tcp);
 764 
 765         tcp->tcp_loopback = (uinfo.iulp_loopback | uinfo.iulp_local);
 766 
 767         /*
 768          * Make sure that conn is not marked incipient
 769          * for incoming connections. A blind
 770          * removal of incipient flag is cheaper than
 771          * check and removal.
 772          */
 773         mutex_enter(&connp->conn_lock);
 774         connp->conn_state_flags &= ~CONN_INCIPIENT;
 775         mutex_exit(&connp->conn_lock);
 776         return (0);
 777 }
 778 
 779 /*
 780  * tcp_clean_death / tcp_close_detached must not be called more than once
 781  * on a tcp. Thus every function that potentially calls tcp_clean_death
 782  * must check for the tcp state before calling tcp_clean_death.
 783  * Eg. tcp_input_data, tcp_eager_kill, tcp_clean_death_wrapper,
 784  * tcp_timer_handler, all check for the tcp state.
 785  */
 786 /* ARGSUSED */
 787 void
 788 tcp_clean_death_wrapper(void *arg, mblk_t *mp, void *arg2,
 789     ip_recv_attr_t *dummy)
 790 {
 791         tcp_t   *tcp = ((conn_t *)arg)->conn_tcp;
 792 
 793         freemsg(mp);
 794         if (tcp->tcp_state > TCPS_BOUND)
 795                 (void) tcp_clean_death(((conn_t *)arg)->conn_tcp, ETIMEDOUT);
 796 }
 797 
 798 /*
 799  * We are dying for some reason.  Try to do it gracefully.  (May be called
 800  * as writer.)
 801  *
 802  * Return -1 if the structure was not cleaned up (if the cleanup had to be
 803  * done by a service procedure).
 804  * TBD - Should the return value distinguish between the tcp_t being
 805  * freed and it being reinitialized?
 806  */
 807 int
 808 tcp_clean_death(tcp_t *tcp, int err)
 809 {
 810         mblk_t  *mp;
 811         queue_t *q;
 812         conn_t  *connp = tcp->tcp_connp;
 813         tcp_stack_t     *tcps = tcp->tcp_tcps;
 814 
 815         if (tcp->tcp_fused)
 816                 tcp_unfuse(tcp);
 817 
 818         if (tcp->tcp_linger_tid != 0 &&
 819             TCP_TIMER_CANCEL(tcp, tcp->tcp_linger_tid) >= 0) {
 820                 tcp_stop_lingering(tcp);
 821         }
 822 
 823         ASSERT(tcp != NULL);
 824         ASSERT((connp->conn_family == AF_INET &&
 825             connp->conn_ipversion == IPV4_VERSION) ||
 826             (connp->conn_family == AF_INET6 &&
 827             (connp->conn_ipversion == IPV4_VERSION ||
 828             connp->conn_ipversion == IPV6_VERSION)));
 829 
 830         if (TCP_IS_DETACHED(tcp)) {
 831                 if (tcp->tcp_hard_binding) {
 832                         /*
 833                          * Its an eager that we are dealing with. We close the
 834                          * eager but in case a conn_ind has already gone to the
 835                          * listener, let tcp_accept_finish() send a discon_ind
 836                          * to the listener and drop the last reference. If the
 837                          * listener doesn't even know about the eager i.e. the
 838                          * conn_ind hasn't gone up, blow away the eager and drop
 839                          * the last reference as well. If the conn_ind has gone
 840                          * up, state should be BOUND. tcp_accept_finish
 841                          * will figure out that the connection has received a
 842                          * RST and will send a DISCON_IND to the application.
 843                          */
 844                         tcp_closei_local(tcp);
 845                         if (!tcp->tcp_tconnind_started) {
 846                                 CONN_DEC_REF(connp);
 847                         } else {
 848                                 tcp->tcp_state = TCPS_BOUND;
 849                                 DTRACE_TCP6(state__change, void, NULL,
 850                                     ip_xmit_attr_t *, connp->conn_ixa,
 851                                     void, NULL, tcp_t *, tcp, void, NULL,
 852                                     int32_t, TCPS_CLOSED);
 853                         }
 854                 } else {
 855                         tcp_close_detached(tcp);
 856                 }
 857                 return (0);
 858         }
 859 
 860         TCP_STAT(tcps, tcp_clean_death_nondetached);
 861 
 862         /*
 863          * The connection is dead.  Decrement listener connection counter if
 864          * necessary.
 865          */
 866         if (tcp->tcp_listen_cnt != NULL)
 867                 TCP_DECR_LISTEN_CNT(tcp);
 868 
 869         /*
 870          * When a connection is moved to TIME_WAIT state, the connection
 871          * counter is already decremented.  So no need to decrement here
 872          * again.  See SET_TIME_WAIT() macro.
 873          */
 874         if (tcp->tcp_state >= TCPS_ESTABLISHED &&
 875             tcp->tcp_state < TCPS_TIME_WAIT) {
 876                 TCPS_CONN_DEC(tcps);
 877         }
 878 
 879         q = connp->conn_rq;
 880 
 881         /* Trash all inbound data */
 882         if (!IPCL_IS_NONSTR(connp)) {
 883                 ASSERT(q != NULL);
 884                 flushq(q, FLUSHALL);
 885         }
 886 
 887         /*
 888          * If we are at least part way open and there is error
 889          * (err==0 implies no error)
 890          * notify our client by a T_DISCON_IND.
 891          */
 892         if ((tcp->tcp_state >= TCPS_SYN_SENT) && err) {
 893                 if (tcp->tcp_state >= TCPS_ESTABLISHED &&
 894                     !TCP_IS_SOCKET(tcp)) {
 895                         /*
 896                          * Send M_FLUSH according to TPI. Because sockets will
 897                          * (and must) ignore FLUSHR we do that only for TPI
 898                          * endpoints and sockets in STREAMS mode.
 899                          */
 900                         (void) putnextctl1(q, M_FLUSH, FLUSHR);
 901                 }
 902                 if (connp->conn_debug) {
 903                         (void) strlog(TCP_MOD_ID, 0, 1, SL_TRACE|SL_ERROR,
 904                             "tcp_clean_death: discon err %d", err);
 905                 }
 906                 if (IPCL_IS_NONSTR(connp)) {
 907                         /* Direct socket, use upcall */
 908                         (*connp->conn_upcalls->su_disconnected)(
 909                             connp->conn_upper_handle, tcp->tcp_connid, err);
 910                 } else {
 911                         mp = mi_tpi_discon_ind(NULL, err, 0);
 912                         if (mp != NULL) {
 913                                 putnext(q, mp);
 914                         } else {
 915                                 if (connp->conn_debug) {
 916                                         (void) strlog(TCP_MOD_ID, 0, 1,
 917                                             SL_ERROR|SL_TRACE,
 918                                             "tcp_clean_death, sending M_ERROR");
 919                                 }
 920                                 (void) putnextctl1(q, M_ERROR, EPROTO);
 921                         }
 922                 }
 923                 if (tcp->tcp_state <= TCPS_SYN_RCVD) {
 924                         /* SYN_SENT or SYN_RCVD */
 925                         TCPS_BUMP_MIB(tcps, tcpAttemptFails);
 926                 } else if (tcp->tcp_state <= TCPS_CLOSE_WAIT) {
 927                         /* ESTABLISHED or CLOSE_WAIT */
 928                         TCPS_BUMP_MIB(tcps, tcpEstabResets);
 929                 }
 930         }
 931 
 932         /*
 933          * ESTABLISHED non-STREAMS eagers are not 'detached' because
 934          * an upper handle is obtained when the SYN-ACK comes in. So it
 935          * should receive the 'disconnected' upcall, but tcp_reinit should
 936          * not be called since this is an eager.
 937          */
 938         if (tcp->tcp_listener != NULL && IPCL_IS_NONSTR(connp)) {
 939                 tcp_closei_local(tcp);
 940                 tcp->tcp_state = TCPS_BOUND;
 941                 DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
 942                     connp->conn_ixa, void, NULL, tcp_t *, tcp, void, NULL,
 943                     int32_t, TCPS_CLOSED);
 944                 return (0);
 945         }
 946 
 947         tcp_reinit(tcp);
 948         if (IPCL_IS_NONSTR(connp))
 949                 (void) tcp_do_unbind(connp);
 950 
 951         return (-1);
 952 }
 953 
 954 /*
 955  * In case tcp is in the "lingering state" and waits for the SO_LINGER timeout
 956  * to expire, stop the wait and finish the close.
 957  */
 958 void
 959 tcp_stop_lingering(tcp_t *tcp)
 960 {
 961         clock_t delta = 0;
 962         tcp_stack_t     *tcps = tcp->tcp_tcps;
 963         conn_t          *connp = tcp->tcp_connp;
 964 
 965         tcp->tcp_linger_tid = 0;
 966         if (tcp->tcp_state > TCPS_LISTEN) {
 967                 tcp_acceptor_hash_remove(tcp);
 968                 mutex_enter(&tcp->tcp_non_sq_lock);
 969                 if (tcp->tcp_flow_stopped) {
 970                         tcp_clrqfull(tcp);
 971                 }
 972                 mutex_exit(&tcp->tcp_non_sq_lock);
 973 
 974                 if (tcp->tcp_timer_tid != 0) {
 975                         delta = TCP_TIMER_CANCEL(tcp, tcp->tcp_timer_tid);
 976                         tcp->tcp_timer_tid = 0;
 977                 }
 978                 /*
 979                  * Need to cancel those timers which will not be used when
 980                  * TCP is detached.  This has to be done before the conn_wq
 981                  * is cleared.
 982                  */
 983                 tcp_timers_stop(tcp);
 984 
 985                 tcp->tcp_detached = B_TRUE;
 986                 connp->conn_rq = NULL;
 987                 connp->conn_wq = NULL;
 988 
 989                 if (tcp->tcp_state == TCPS_TIME_WAIT) {
 990                         tcp_time_wait_append(tcp);
 991                         TCP_DBGSTAT(tcps, tcp_detach_time_wait);
 992                         goto finish;
 993                 }
 994 
 995                 /*
 996                  * If delta is zero the timer event wasn't executed and was
 997                  * successfully canceled. In this case we need to restart it
 998                  * with the minimal delta possible.
 999                  */
1000                 if (delta >= 0) {
1001                         tcp->tcp_timer_tid = TCP_TIMER(tcp, tcp_timer,
1002                             delta ? delta : 1);
1003                 }
1004         } else {
1005                 tcp_closei_local(tcp);
1006                 CONN_DEC_REF(connp);
1007         }
1008 finish:
1009         tcp->tcp_detached = B_TRUE;
1010         connp->conn_rq = NULL;
1011         connp->conn_wq = NULL;
1012 
1013         /* Signal closing thread that it can complete close */
1014         mutex_enter(&tcp->tcp_closelock);
1015         tcp->tcp_closed = 1;
1016         cv_signal(&tcp->tcp_closecv);
1017         mutex_exit(&tcp->tcp_closelock);
1018 
1019         /* If we have an upper handle (socket), release it */
1020         if (IPCL_IS_NONSTR(connp)) {
1021                 ASSERT(connp->conn_upper_handle != NULL);
1022                 (*connp->conn_upcalls->su_closed)(connp->conn_upper_handle);
1023                 connp->conn_upper_handle = NULL;
1024                 connp->conn_upcalls = NULL;
1025         }
1026 }
1027 
1028 void
1029 tcp_close_common(conn_t *connp, int flags)
1030 {
1031         tcp_t           *tcp = connp->conn_tcp;
1032         mblk_t          *mp = &tcp->tcp_closemp;
1033         boolean_t       conn_ioctl_cleanup_reqd = B_FALSE;
1034         mblk_t          *bp;
1035 
1036         ASSERT(connp->conn_ref >= 2);
1037 
1038         /*
1039          * Mark the conn as closing. ipsq_pending_mp_add will not
1040          * add any mp to the pending mp list, after this conn has
1041          * started closing.
1042          */
1043         mutex_enter(&connp->conn_lock);
1044         connp->conn_state_flags |= CONN_CLOSING;
1045         if (connp->conn_oper_pending_ill != NULL)
1046                 conn_ioctl_cleanup_reqd = B_TRUE;
1047         CONN_INC_REF_LOCKED(connp);
1048         mutex_exit(&connp->conn_lock);
1049         tcp->tcp_closeflags = (uint8_t)flags;
1050         ASSERT(connp->conn_ref >= 3);
1051 
1052         /*
1053          * tcp_closemp_used is used below without any protection of a lock
1054          * as we don't expect any one else to use it concurrently at this
1055          * point otherwise it would be a major defect.
1056          */
1057 
1058         if (mp->b_prev == NULL)
1059                 tcp->tcp_closemp_used = B_TRUE;
1060         else
1061                 cmn_err(CE_PANIC, "tcp_close: concurrent use of tcp_closemp: "
1062                     "connp %p tcp %p\n", (void *)connp, (void *)tcp);
1063 
1064         TCP_DEBUG_GETPCSTACK(tcp->tcmp_stk, 15);
1065 
1066         /*
1067          * Cleanup any queued ioctls here. This must be done before the wq/rq
1068          * are re-written by tcp_close_output().
1069          */
1070         if (conn_ioctl_cleanup_reqd)
1071                 conn_ioctl_cleanup(connp);
1072 
1073         /*
1074          * As CONN_CLOSING is set, no further ioctls should be passed down to
1075          * IP for this conn (see the guards in tcp_ioctl, tcp_wput_ioctl and
1076          * tcp_wput_iocdata). If the ioctl was queued on an ipsq,
1077          * conn_ioctl_cleanup should have found it and removed it. If the ioctl
1078          * was still in flight at the time, we wait for it here. See comments
1079          * for CONN_INC_IOCTLREF in ip.h for details.
1080          */
1081         mutex_enter(&connp->conn_lock);
1082         while (connp->conn_ioctlref > 0)
1083                 cv_wait(&connp->conn_cv, &connp->conn_lock);
1084         ASSERT(connp->conn_ioctlref == 0);
1085         ASSERT(connp->conn_oper_pending_ill == NULL);
1086         mutex_exit(&connp->conn_lock);
1087 
1088         SQUEUE_ENTER_ONE(connp->conn_sqp, mp, tcp_close_output, connp,
1089             NULL, tcp_squeue_flag, SQTAG_IP_TCP_CLOSE);
1090 
1091         /*
1092          * For non-STREAMS sockets, the normal case is that the conn makes
1093          * an upcall when it's finally closed, so there is no need to wait
1094          * in the protocol. But in case of SO_LINGER the thread sleeps here
1095          * so it can properly deal with the thread being interrupted.
1096          */
1097         if (IPCL_IS_NONSTR(connp) && connp->conn_linger == 0)
1098                 goto nowait;
1099 
1100         mutex_enter(&tcp->tcp_closelock);
1101         while (!tcp->tcp_closed) {
1102                 if (!cv_wait_sig(&tcp->tcp_closecv, &tcp->tcp_closelock)) {
1103                         /*
1104                          * The cv_wait_sig() was interrupted. We now do the
1105                          * following:
1106                          *
1107                          * 1) If the endpoint was lingering, we allow this
1108                          * to be interrupted by cancelling the linger timeout
1109                          * and closing normally.
1110                          *
1111                          * 2) Revert to calling cv_wait()
1112                          *
1113                          * We revert to using cv_wait() to avoid an
1114                          * infinite loop which can occur if the calling
1115                          * thread is higher priority than the squeue worker
1116                          * thread and is bound to the same cpu.
1117                          */
1118                         if (connp->conn_linger && connp->conn_lingertime > 0) {
1119                                 mutex_exit(&tcp->tcp_closelock);
1120                                 /* Entering squeue, bump ref count. */
1121                                 CONN_INC_REF(connp);
1122                                 bp = allocb_wait(0, BPRI_HI, STR_NOSIG, NULL);
1123                                 SQUEUE_ENTER_ONE(connp->conn_sqp, bp,
1124                                     tcp_linger_interrupted, connp, NULL,
1125                                     tcp_squeue_flag, SQTAG_IP_TCP_CLOSE);
1126                                 mutex_enter(&tcp->tcp_closelock);
1127                         }
1128                         break;
1129                 }
1130         }
1131         while (!tcp->tcp_closed)
1132                 cv_wait(&tcp->tcp_closecv, &tcp->tcp_closelock);
1133         mutex_exit(&tcp->tcp_closelock);
1134 
1135         /*
1136          * In the case of listener streams that have eagers in the q or q0
1137          * we wait for the eagers to drop their reference to us. conn_rq and
1138          * conn_wq of the eagers point to our queues. By waiting for the
1139          * refcnt to drop to 1, we are sure that the eagers have cleaned
1140          * up their queue pointers and also dropped their references to us.
1141          *
1142          * For non-STREAMS sockets we do not have to wait here; the
1143          * listener will instead make a su_closed upcall when the last
1144          * reference is dropped.
1145          */
1146         if (tcp->tcp_wait_for_eagers && !IPCL_IS_NONSTR(connp)) {
1147                 mutex_enter(&connp->conn_lock);
1148                 while (connp->conn_ref != 1) {
1149                         cv_wait(&connp->conn_cv, &connp->conn_lock);
1150                 }
1151                 mutex_exit(&connp->conn_lock);
1152         }
1153 
1154 nowait:
1155         connp->conn_cpid = NOPID;
1156 }
1157 
1158 /*
1159  * Called by tcp_close() routine via squeue when lingering is
1160  * interrupted by a signal.
1161  */
1162 
1163 /* ARGSUSED */
1164 static void
1165 tcp_linger_interrupted(void *arg, mblk_t *mp, void *arg2, ip_recv_attr_t *dummy)
1166 {
1167         conn_t  *connp = (conn_t *)arg;
1168         tcp_t   *tcp = connp->conn_tcp;
1169 
1170         freeb(mp);
1171         if (tcp->tcp_linger_tid != 0 &&
1172             TCP_TIMER_CANCEL(tcp, tcp->tcp_linger_tid) >= 0) {
1173                 tcp_stop_lingering(tcp);
1174                 tcp->tcp_client_errno = EINTR;
1175         }
1176 }
1177 
1178 /*
1179  * Clean up the b_next and b_prev fields of every mblk pointed at by *mpp.
1180  * Some stream heads get upset if they see these later on as anything but NULL.
1181  */
1182 void
1183 tcp_close_mpp(mblk_t **mpp)
1184 {
1185         mblk_t  *mp;
1186 
1187         if ((mp = *mpp) != NULL) {
1188                 do {
1189                         mp->b_next = NULL;
1190                         mp->b_prev = NULL;
1191                 } while ((mp = mp->b_cont) != NULL);
1192 
1193                 mp = *mpp;
1194                 *mpp = NULL;
1195                 freemsg(mp);
1196         }
1197 }
1198 
1199 /* Do detached close. */
1200 void
1201 tcp_close_detached(tcp_t *tcp)
1202 {
1203         if (tcp->tcp_fused)
1204                 tcp_unfuse(tcp);
1205 
1206         /*
1207          * Clustering code serializes TCP disconnect callbacks and
1208          * cluster tcp list walks by blocking a TCP disconnect callback
1209          * if a cluster tcp list walk is in progress. This ensures
1210          * accurate accounting of TCPs in the cluster code even though
1211          * the TCP list walk itself is not atomic.
1212          */
1213         tcp_closei_local(tcp);
1214         CONN_DEC_REF(tcp->tcp_connp);
1215 }
1216 
1217 /*
1218  * The tcp_t is going away. Remove it from all lists and set it
1219  * to TCPS_CLOSED. The freeing up of memory is deferred until
1220  * tcp_inactive. This is needed since a thread in tcp_rput might have
1221  * done a CONN_INC_REF on this structure before it was removed from the
1222  * hashes.
1223  */
1224 void
1225 tcp_closei_local(tcp_t *tcp)
1226 {
1227         conn_t          *connp = tcp->tcp_connp;
1228         tcp_stack_t     *tcps = tcp->tcp_tcps;
1229         int32_t         oldstate;
1230 
1231         if (!TCP_IS_SOCKET(tcp))
1232                 tcp_acceptor_hash_remove(tcp);
1233 
1234         TCPS_UPDATE_MIB(tcps, tcpHCInSegs, tcp->tcp_ibsegs);
1235         tcp->tcp_ibsegs = 0;
1236         TCPS_UPDATE_MIB(tcps, tcpHCOutSegs, tcp->tcp_obsegs);
1237         tcp->tcp_obsegs = 0;
1238 
1239         /*
1240          * This can be called via tcp_time_wait_processing() if TCP gets a
1241          * SYN with sequence number outside the TIME-WAIT connection's
1242          * window.  So we need to check for TIME-WAIT state here as the
1243          * connection counter is already decremented.  See SET_TIME_WAIT()
1244          * macro
1245          */
1246         if (tcp->tcp_state >= TCPS_ESTABLISHED &&
1247             tcp->tcp_state < TCPS_TIME_WAIT) {
1248                 TCPS_CONN_DEC(tcps);
1249         }
1250 
1251         /*
1252          * If we are an eager connection hanging off a listener that
1253          * hasn't formally accepted the connection yet, get off its
1254          * list and blow off any data that we have accumulated.
1255          */
1256         if (tcp->tcp_listener != NULL) {
1257                 tcp_t   *listener = tcp->tcp_listener;
1258                 mutex_enter(&listener->tcp_eager_lock);
1259                 /*
1260                  * tcp_tconnind_started == B_TRUE means that the
1261                  * conn_ind has already gone to listener. At
1262                  * this point, eager will be closed but we
1263                  * leave it in listeners eager list so that
1264                  * if listener decides to close without doing
1265                  * accept, we can clean this up. In tcp_tli_accept
1266                  * we take care of the case of accept on closed
1267                  * eager.
1268                  */
1269                 if (!tcp->tcp_tconnind_started) {
1270                         tcp_eager_unlink(tcp);
1271                         mutex_exit(&listener->tcp_eager_lock);
1272                         /*
1273                          * We don't want to have any pointers to the
1274                          * listener queue, after we have released our
1275                          * reference on the listener
1276                          */
1277                         ASSERT(tcp->tcp_detached);
1278                         connp->conn_rq = NULL;
1279                         connp->conn_wq = NULL;
1280                         CONN_DEC_REF(listener->tcp_connp);
1281                 } else {
1282                         mutex_exit(&listener->tcp_eager_lock);
1283                 }
1284         }
1285 
1286         /* Stop all the timers */
1287         tcp_timers_stop(tcp);
1288 
1289         if (tcp->tcp_state == TCPS_LISTEN) {
1290                 if (tcp->tcp_ip_addr_cache) {
1291                         kmem_free((void *)tcp->tcp_ip_addr_cache,
1292                             IP_ADDR_CACHE_SIZE * sizeof (ipaddr_t));
1293                         tcp->tcp_ip_addr_cache = NULL;
1294                 }
1295         }
1296 
1297         /* Decrement listerner connection counter if necessary. */
1298         if (tcp->tcp_listen_cnt != NULL)
1299                 TCP_DECR_LISTEN_CNT(tcp);
1300 
1301         mutex_enter(&tcp->tcp_non_sq_lock);
1302         if (tcp->tcp_flow_stopped)
1303                 tcp_clrqfull(tcp);
1304         mutex_exit(&tcp->tcp_non_sq_lock);
1305 
1306         tcp_bind_hash_remove(tcp);
1307         /*
1308          * If the tcp_time_wait_collector (which runs outside the squeue)
1309          * is trying to remove this tcp from the time wait list, we will
1310          * block in tcp_time_wait_remove while trying to acquire the
1311          * tcp_time_wait_lock. The logic in tcp_time_wait_collector also
1312          * requires the ipcl_hash_remove to be ordered after the
1313          * tcp_time_wait_remove for the refcnt checks to work correctly.
1314          */
1315         if (tcp->tcp_state == TCPS_TIME_WAIT)
1316                 (void) tcp_time_wait_remove(tcp, NULL);
1317         CL_INET_DISCONNECT(connp);
1318         ipcl_hash_remove(connp);
1319         oldstate = tcp->tcp_state;
1320         tcp->tcp_state = TCPS_CLOSED;
1321         /* Need to probe before ixa_cleanup() is called */
1322         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
1323             connp->conn_ixa, void, NULL, tcp_t *, tcp, void, NULL,
1324             int32_t, oldstate);
1325         ixa_cleanup(connp->conn_ixa);
1326 
1327         /*
1328          * Mark the conn as CONDEMNED
1329          */
1330         mutex_enter(&connp->conn_lock);
1331         connp->conn_state_flags |= CONN_CONDEMNED;
1332         mutex_exit(&connp->conn_lock);
1333 
1334         ASSERT(tcp->tcp_time_wait_next == NULL);
1335         ASSERT(tcp->tcp_time_wait_prev == NULL);
1336         ASSERT(tcp->tcp_time_wait_expire == 0);
1337 
1338         tcp_ipsec_cleanup(tcp);
1339 }
1340 
1341 /*
1342  * tcp is dying (called from ipcl_conn_destroy and error cases).
1343  * Free the tcp_t in either case.
1344  */
1345 void
1346 tcp_free(tcp_t *tcp)
1347 {
1348         mblk_t          *mp;
1349         conn_t          *connp = tcp->tcp_connp;
1350 
1351         ASSERT(tcp != NULL);
1352         ASSERT(tcp->tcp_ptpahn == NULL && tcp->tcp_acceptor_hash == NULL);
1353 
1354         connp->conn_rq = NULL;
1355         connp->conn_wq = NULL;
1356 
1357         tcp_close_mpp(&tcp->tcp_xmit_head);
1358         tcp_close_mpp(&tcp->tcp_reass_head);
1359         if (tcp->tcp_rcv_list != NULL) {
1360                 /* Free b_next chain */
1361                 tcp_close_mpp(&tcp->tcp_rcv_list);
1362         }
1363         if ((mp = tcp->tcp_urp_mp) != NULL) {
1364                 freemsg(mp);
1365         }
1366         if ((mp = tcp->tcp_urp_mark_mp) != NULL) {
1367                 freemsg(mp);
1368         }
1369 
1370         if (tcp->tcp_fused_sigurg_mp != NULL) {
1371                 ASSERT(!IPCL_IS_NONSTR(tcp->tcp_connp));
1372                 freeb(tcp->tcp_fused_sigurg_mp);
1373                 tcp->tcp_fused_sigurg_mp = NULL;
1374         }
1375 
1376         if (tcp->tcp_ordrel_mp != NULL) {
1377                 ASSERT(!IPCL_IS_NONSTR(tcp->tcp_connp));
1378                 freeb(tcp->tcp_ordrel_mp);
1379                 tcp->tcp_ordrel_mp = NULL;
1380         }
1381 
1382         TCP_NOTSACK_REMOVE_ALL(tcp->tcp_notsack_list, tcp);
1383         bzero(&tcp->tcp_sack_info, sizeof (tcp_sack_info_t));
1384 
1385         if (tcp->tcp_hopopts != NULL) {
1386                 mi_free(tcp->tcp_hopopts);
1387                 tcp->tcp_hopopts = NULL;
1388                 tcp->tcp_hopoptslen = 0;
1389         }
1390         ASSERT(tcp->tcp_hopoptslen == 0);
1391         if (tcp->tcp_dstopts != NULL) {
1392                 mi_free(tcp->tcp_dstopts);
1393                 tcp->tcp_dstopts = NULL;
1394                 tcp->tcp_dstoptslen = 0;
1395         }
1396         ASSERT(tcp->tcp_dstoptslen == 0);
1397         if (tcp->tcp_rthdrdstopts != NULL) {
1398                 mi_free(tcp->tcp_rthdrdstopts);
1399                 tcp->tcp_rthdrdstopts = NULL;
1400                 tcp->tcp_rthdrdstoptslen = 0;
1401         }
1402         ASSERT(tcp->tcp_rthdrdstoptslen == 0);
1403         if (tcp->tcp_rthdr != NULL) {
1404                 mi_free(tcp->tcp_rthdr);
1405                 tcp->tcp_rthdr = NULL;
1406                 tcp->tcp_rthdrlen = 0;
1407         }
1408         ASSERT(tcp->tcp_rthdrlen == 0);
1409 
1410         /*
1411          * Following is really a blowing away a union.
1412          * It happens to have exactly two members of identical size
1413          * the following code is enough.
1414          */
1415         tcp_close_mpp(&tcp->tcp_conn.tcp_eager_conn_ind);
1416 
1417         /*
1418          * If this is a non-STREAM socket still holding on to an upper
1419          * handle, release it. As a result of fallback we might also see
1420          * STREAMS based conns with upper handles, in which case there is
1421          * nothing to do other than clearing the field.
1422          */
1423         if (connp->conn_upper_handle != NULL) {
1424                 if (IPCL_IS_NONSTR(connp)) {
1425                         (*connp->conn_upcalls->su_closed)(
1426                             connp->conn_upper_handle);
1427                         tcp->tcp_detached = B_TRUE;
1428                 }
1429                 connp->conn_upper_handle = NULL;
1430                 connp->conn_upcalls = NULL;
1431         }
1432 }
1433 
1434 /*
1435  * tcp_get_conn/tcp_free_conn
1436  *
1437  * tcp_get_conn is used to get a clean tcp connection structure.
1438  * It tries to reuse the connections put on the freelist by the
1439  * time_wait_collector failing which it goes to kmem_cache. This
1440  * way has two benefits compared to just allocating from and
1441  * freeing to kmem_cache.
1442  * 1) The time_wait_collector can free (which includes the cleanup)
1443  * outside the squeue. So when the interrupt comes, we have a clean
1444  * connection sitting in the freelist. Obviously, this buys us
1445  * performance.
1446  *
1447  * 2) Defence against DOS attack. Allocating a tcp/conn in tcp_input_listener
1448  * has multiple disadvantages - tying up the squeue during alloc.
1449  * But allocating the conn/tcp in IP land is also not the best since
1450  * we can't check the 'q' and 'q0' which are protected by squeue and
1451  * blindly allocate memory which might have to be freed here if we are
1452  * not allowed to accept the connection. By using the freelist and
1453  * putting the conn/tcp back in freelist, we don't pay a penalty for
1454  * allocating memory without checking 'q/q0' and freeing it if we can't
1455  * accept the connection.
1456  *
1457  * Care should be taken to put the conn back in the same squeue's freelist
1458  * from which it was allocated. Best results are obtained if conn is
1459  * allocated from listener's squeue and freed to the same. Time wait
1460  * collector will free up the freelist is the connection ends up sitting
1461  * there for too long.
1462  */
1463 void *
1464 tcp_get_conn(void *arg, tcp_stack_t *tcps)
1465 {
1466         tcp_t                   *tcp = NULL;
1467         conn_t                  *connp = NULL;
1468         squeue_t                *sqp = (squeue_t *)arg;
1469         tcp_squeue_priv_t       *tcp_time_wait;
1470         netstack_t              *ns;
1471         mblk_t                  *tcp_rsrv_mp = NULL;
1472 
1473         tcp_time_wait =
1474             *((tcp_squeue_priv_t **)squeue_getprivate(sqp, SQPRIVATE_TCP));
1475 
1476         mutex_enter(&tcp_time_wait->tcp_time_wait_lock);
1477         tcp = tcp_time_wait->tcp_free_list;
1478         ASSERT((tcp != NULL) ^ (tcp_time_wait->tcp_free_list_cnt == 0));
1479         if (tcp != NULL) {
1480                 tcp_time_wait->tcp_free_list = tcp->tcp_time_wait_next;
1481                 tcp_time_wait->tcp_free_list_cnt--;
1482                 mutex_exit(&tcp_time_wait->tcp_time_wait_lock);
1483                 tcp->tcp_time_wait_next = NULL;
1484                 connp = tcp->tcp_connp;
1485                 connp->conn_flags |= IPCL_REUSED;
1486 
1487                 ASSERT(tcp->tcp_tcps == NULL);
1488                 ASSERT(connp->conn_netstack == NULL);
1489                 ASSERT(tcp->tcp_rsrv_mp != NULL);
1490                 ns = tcps->tcps_netstack;
1491                 netstack_hold(ns);
1492                 connp->conn_netstack = ns;
1493                 connp->conn_ixa->ixa_ipst = ns->netstack_ip;
1494                 tcp->tcp_tcps = tcps;
1495                 ipcl_globalhash_insert(connp);
1496 
1497                 connp->conn_ixa->ixa_notify_cookie = tcp;
1498                 ASSERT(connp->conn_ixa->ixa_notify == tcp_notify);
1499                 connp->conn_recv = tcp_input_data;
1500                 ASSERT(connp->conn_recvicmp == tcp_icmp_input);
1501                 ASSERT(connp->conn_verifyicmp == tcp_verifyicmp);
1502                 return ((void *)connp);
1503         }
1504         mutex_exit(&tcp_time_wait->tcp_time_wait_lock);
1505         /*
1506          * Pre-allocate the tcp_rsrv_mp. This mblk will not be freed until
1507          * this conn_t/tcp_t is freed at ipcl_conn_destroy().
1508          */
1509         tcp_rsrv_mp = allocb(0, BPRI_HI);
1510         if (tcp_rsrv_mp == NULL)
1511                 return (NULL);
1512 
1513         if ((connp = ipcl_conn_create(IPCL_TCPCONN, KM_NOSLEEP,
1514             tcps->tcps_netstack)) == NULL) {
1515                 freeb(tcp_rsrv_mp);
1516                 return (NULL);
1517         }
1518 
1519         tcp = connp->conn_tcp;
1520         tcp->tcp_rsrv_mp = tcp_rsrv_mp;
1521         mutex_init(&tcp->tcp_rsrv_mp_lock, NULL, MUTEX_DEFAULT, NULL);
1522 
1523         tcp->tcp_tcps = tcps;
1524 
1525         connp->conn_recv = tcp_input_data;
1526         connp->conn_recvicmp = tcp_icmp_input;
1527         connp->conn_verifyicmp = tcp_verifyicmp;
1528 
1529         /*
1530          * Register tcp_notify to listen to capability changes detected by IP.
1531          * This upcall is made in the context of the call to conn_ip_output
1532          * thus it is inside the squeue.
1533          */
1534         connp->conn_ixa->ixa_notify = tcp_notify;
1535         connp->conn_ixa->ixa_notify_cookie = tcp;
1536 
1537         return ((void *)connp);
1538 }
1539 
1540 /*
1541  * Handle connect to IPv4 destinations, including connections for AF_INET6
1542  * sockets connecting to IPv4 mapped IPv6 destinations.
1543  * Returns zero if OK, a positive errno, or a negative TLI error.
1544  */
1545 static int
1546 tcp_connect_ipv4(tcp_t *tcp, ipaddr_t *dstaddrp, in_port_t dstport,
1547     uint_t srcid)
1548 {
1549         ipaddr_t        dstaddr = *dstaddrp;
1550         uint16_t        lport;
1551         conn_t          *connp = tcp->tcp_connp;
1552         tcp_stack_t     *tcps = tcp->tcp_tcps;
1553         int             error;
1554 
1555         ASSERT(connp->conn_ipversion == IPV4_VERSION);
1556 
1557         /* Check for attempt to connect to INADDR_ANY */
1558         if (dstaddr == INADDR_ANY)  {
1559                 /*
1560                  * SunOS 4.x and 4.3 BSD allow an application
1561                  * to connect a TCP socket to INADDR_ANY.
1562                  * When they do this, the kernel picks the
1563                  * address of one interface and uses it
1564                  * instead.  The kernel usually ends up
1565                  * picking the address of the loopback
1566                  * interface.  This is an undocumented feature.
1567                  * However, we provide the same thing here
1568                  * in order to have source and binary
1569                  * compatibility with SunOS 4.x.
1570                  * Update the T_CONN_REQ (sin/sin6) since it is used to
1571                  * generate the T_CONN_CON.
1572                  */
1573                 dstaddr = htonl(INADDR_LOOPBACK);
1574                 *dstaddrp = dstaddr;
1575         }
1576 
1577         /* Handle __sin6_src_id if socket not bound to an IP address */
1578         if (srcid != 0 && connp->conn_laddr_v4 == INADDR_ANY) {
1579                 if (!ip_srcid_find_id(srcid, &connp->conn_laddr_v6,
1580                     IPCL_ZONEID(connp), B_TRUE, tcps->tcps_netstack)) {
1581                         /* Mismatch - conn_laddr_v6 would be v6 address. */
1582                         return (EADDRNOTAVAIL);
1583                 }
1584                 connp->conn_saddr_v6 = connp->conn_laddr_v6;
1585         }
1586 
1587         IN6_IPADDR_TO_V4MAPPED(dstaddr, &connp->conn_faddr_v6);
1588         connp->conn_fport = dstport;
1589 
1590         /*
1591          * At this point the remote destination address and remote port fields
1592          * in the tcp-four-tuple have been filled in the tcp structure. Now we
1593          * have to see which state tcp was in so we can take appropriate action.
1594          */
1595         if (tcp->tcp_state == TCPS_IDLE) {
1596                 /*
1597                  * We support a quick connect capability here, allowing
1598                  * clients to transition directly from IDLE to SYN_SENT
1599                  * tcp_bindi will pick an unused port, insert the connection
1600                  * in the bind hash and transition to BOUND state.
1601                  */
1602                 lport = tcp_update_next_port(tcps->tcps_next_port_to_try,
1603                     tcp, B_TRUE);
1604                 lport = tcp_bindi(tcp, lport, &connp->conn_laddr_v6, 0, B_TRUE,
1605                     B_FALSE, B_FALSE);
1606                 if (lport == 0)
1607                         return (-TNOADDR);
1608         }
1609 
1610         /*
1611          * Lookup the route to determine a source address and the uinfo.
1612          * Setup TCP parameters based on the metrics/DCE.
1613          */
1614         error = tcp_set_destination(tcp);
1615         if (error != 0)
1616                 return (error);
1617 
1618         /*
1619          * Don't let an endpoint connect to itself.
1620          */
1621         if (connp->conn_faddr_v4 == connp->conn_laddr_v4 &&
1622             connp->conn_fport == connp->conn_lport)
1623                 return (-TBADADDR);
1624 
1625         tcp->tcp_state = TCPS_SYN_SENT;
1626 
1627         return (ipcl_conn_insert_v4(connp));
1628 }
1629 
1630 /*
1631  * Handle connect to IPv6 destinations.
1632  * Returns zero if OK, a positive errno, or a negative TLI error.
1633  */
1634 static int
1635 tcp_connect_ipv6(tcp_t *tcp, in6_addr_t *dstaddrp, in_port_t dstport,
1636     uint32_t flowinfo, uint_t srcid, uint32_t scope_id)
1637 {
1638         uint16_t        lport;
1639         conn_t          *connp = tcp->tcp_connp;
1640         tcp_stack_t     *tcps = tcp->tcp_tcps;
1641         int             error;
1642 
1643         ASSERT(connp->conn_family == AF_INET6);
1644 
1645         /*
1646          * If we're here, it means that the destination address is a native
1647          * IPv6 address.  Return an error if conn_ipversion is not IPv6.  A
1648          * reason why it might not be IPv6 is if the socket was bound to an
1649          * IPv4-mapped IPv6 address.
1650          */
1651         if (connp->conn_ipversion != IPV6_VERSION)
1652                 return (-TBADADDR);
1653 
1654         /*
1655          * Interpret a zero destination to mean loopback.
1656          * Update the T_CONN_REQ (sin/sin6) since it is used to
1657          * generate the T_CONN_CON.
1658          */
1659         if (IN6_IS_ADDR_UNSPECIFIED(dstaddrp))
1660                 *dstaddrp = ipv6_loopback;
1661 
1662         /* Handle __sin6_src_id if socket not bound to an IP address */
1663         if (srcid != 0 && IN6_IS_ADDR_UNSPECIFIED(&connp->conn_laddr_v6)) {
1664                 if (!ip_srcid_find_id(srcid, &connp->conn_laddr_v6,
1665                     IPCL_ZONEID(connp), B_FALSE, tcps->tcps_netstack)) {
1666                         /* Mismatch - conn_laddr_v6 would be v4-mapped. */
1667                         return (EADDRNOTAVAIL);
1668                 }
1669                 connp->conn_saddr_v6 = connp->conn_laddr_v6;
1670         }
1671 
1672         /*
1673          * Take care of the scope_id now.
1674          */
1675         if (scope_id != 0 && IN6_IS_ADDR_LINKSCOPE(dstaddrp)) {
1676                 connp->conn_ixa->ixa_flags |= IXAF_SCOPEID_SET;
1677                 connp->conn_ixa->ixa_scopeid = scope_id;
1678         } else {
1679                 connp->conn_ixa->ixa_flags &= ~IXAF_SCOPEID_SET;
1680         }
1681 
1682         connp->conn_flowinfo = flowinfo;
1683         connp->conn_faddr_v6 = *dstaddrp;
1684         connp->conn_fport = dstport;
1685 
1686         /*
1687          * At this point the remote destination address and remote port fields
1688          * in the tcp-four-tuple have been filled in the tcp structure. Now we
1689          * have to see which state tcp was in so we can take appropriate action.
1690          */
1691         if (tcp->tcp_state == TCPS_IDLE) {
1692                 /*
1693                  * We support a quick connect capability here, allowing
1694                  * clients to transition directly from IDLE to SYN_SENT
1695                  * tcp_bindi will pick an unused port, insert the connection
1696                  * in the bind hash and transition to BOUND state.
1697                  */
1698                 lport = tcp_update_next_port(tcps->tcps_next_port_to_try,
1699                     tcp, B_TRUE);
1700                 lport = tcp_bindi(tcp, lport, &connp->conn_laddr_v6, 0, B_TRUE,
1701                     B_FALSE, B_FALSE);
1702                 if (lport == 0)
1703                         return (-TNOADDR);
1704         }
1705 
1706         /*
1707          * Lookup the route to determine a source address and the uinfo.
1708          * Setup TCP parameters based on the metrics/DCE.
1709          */
1710         error = tcp_set_destination(tcp);
1711         if (error != 0)
1712                 return (error);
1713 
1714         /*
1715          * Don't let an endpoint connect to itself.
1716          */
1717         if (IN6_ARE_ADDR_EQUAL(&connp->conn_faddr_v6, &connp->conn_laddr_v6) &&
1718             connp->conn_fport == connp->conn_lport)
1719                 return (-TBADADDR);
1720 
1721         tcp->tcp_state = TCPS_SYN_SENT;
1722 
1723         return (ipcl_conn_insert_v6(connp));
1724 }
1725 
1726 /*
1727  * Disconnect
1728  * Note that unlike other functions this returns a positive tli error
1729  * when it fails; it never returns an errno.
1730  */
1731 static int
1732 tcp_disconnect_common(tcp_t *tcp, t_scalar_t seqnum)
1733 {
1734         conn_t          *lconnp;
1735         tcp_stack_t     *tcps = tcp->tcp_tcps;
1736         conn_t          *connp = tcp->tcp_connp;
1737 
1738         /*
1739          * Right now, upper modules pass down a T_DISCON_REQ to TCP,
1740          * when the stream is in BOUND state. Do not send a reset,
1741          * since the destination IP address is not valid, and it can
1742          * be the initialized value of all zeros (broadcast address).
1743          */
1744         if (tcp->tcp_state <= TCPS_BOUND) {
1745                 if (connp->conn_debug) {
1746                         (void) strlog(TCP_MOD_ID, 0, 1, SL_ERROR|SL_TRACE,
1747                             "tcp_disconnect: bad state, %d", tcp->tcp_state);
1748                 }
1749                 return (TOUTSTATE);
1750         } else if (tcp->tcp_state >= TCPS_ESTABLISHED) {
1751                 TCPS_CONN_DEC(tcps);
1752         }
1753 
1754         if (seqnum == -1 || tcp->tcp_conn_req_max == 0) {
1755 
1756                 /*
1757                  * According to TPI, for non-listeners, ignore seqnum
1758                  * and disconnect.
1759                  * Following interpretation of -1 seqnum is historical
1760                  * and implied TPI ? (TPI only states that for T_CONN_IND,
1761                  * a valid seqnum should not be -1).
1762                  *
1763                  *      -1 means disconnect everything
1764                  *      regardless even on a listener.
1765                  */
1766 
1767                 int old_state = tcp->tcp_state;
1768                 ip_stack_t *ipst = tcps->tcps_netstack->netstack_ip;
1769 
1770                 /*
1771                  * The connection can't be on the tcp_time_wait_head list
1772                  * since it is not detached.
1773                  */
1774                 ASSERT(tcp->tcp_time_wait_next == NULL);
1775                 ASSERT(tcp->tcp_time_wait_prev == NULL);
1776                 ASSERT(tcp->tcp_time_wait_expire == 0);
1777                 /*
1778                  * If it used to be a listener, check to make sure no one else
1779                  * has taken the port before switching back to LISTEN state.
1780                  */
1781                 if (connp->conn_ipversion == IPV4_VERSION) {
1782                         lconnp = ipcl_lookup_listener_v4(connp->conn_lport,
1783                             connp->conn_laddr_v4, IPCL_ZONEID(connp), ipst);
1784                 } else {
1785                         uint_t ifindex = 0;
1786 
1787                         if (connp->conn_ixa->ixa_flags & IXAF_SCOPEID_SET)
1788                                 ifindex = connp->conn_ixa->ixa_scopeid;
1789 
1790                         /* Allow conn_bound_if listeners? */
1791                         lconnp = ipcl_lookup_listener_v6(connp->conn_lport,
1792                             &connp->conn_laddr_v6, ifindex, IPCL_ZONEID(connp),
1793                             ipst);
1794                 }
1795                 if (tcp->tcp_conn_req_max && lconnp == NULL) {
1796                         tcp->tcp_state = TCPS_LISTEN;
1797                         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
1798                             connp->conn_ixa, void, NULL, tcp_t *, tcp, void,
1799                             NULL, int32_t, old_state);
1800                 } else if (old_state > TCPS_BOUND) {
1801                         tcp->tcp_conn_req_max = 0;
1802                         tcp->tcp_state = TCPS_BOUND;
1803                         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
1804                             connp->conn_ixa, void, NULL, tcp_t *, tcp, void,
1805                             NULL, int32_t, old_state);
1806 
1807                         /*
1808                          * If this end point is not going to become a listener,
1809                          * decrement the listener connection count if
1810                          * necessary.  Note that we do not do this if it is
1811                          * going to be a listner (the above if case) since
1812                          * then it may remove the counter struct.
1813                          */
1814                         if (tcp->tcp_listen_cnt != NULL)
1815                                 TCP_DECR_LISTEN_CNT(tcp);
1816                 }
1817                 if (lconnp != NULL)
1818                         CONN_DEC_REF(lconnp);
1819                 switch (old_state) {
1820                 case TCPS_SYN_SENT:
1821                 case TCPS_SYN_RCVD:
1822                         TCPS_BUMP_MIB(tcps, tcpAttemptFails);
1823                         break;
1824                 case TCPS_ESTABLISHED:
1825                 case TCPS_CLOSE_WAIT:
1826                         TCPS_BUMP_MIB(tcps, tcpEstabResets);
1827                         break;
1828                 }
1829 
1830                 if (tcp->tcp_fused)
1831                         tcp_unfuse(tcp);
1832 
1833                 mutex_enter(&tcp->tcp_eager_lock);
1834                 if ((tcp->tcp_conn_req_cnt_q0 != 0) ||
1835                     (tcp->tcp_conn_req_cnt_q != 0)) {
1836                         tcp_eager_cleanup(tcp, 0);
1837                 }
1838                 mutex_exit(&tcp->tcp_eager_lock);
1839 
1840                 tcp_xmit_ctl("tcp_disconnect", tcp, tcp->tcp_snxt,
1841                     tcp->tcp_rnxt, TH_RST | TH_ACK);
1842 
1843                 tcp_reinit(tcp);
1844 
1845                 return (0);
1846         } else if (!tcp_eager_blowoff(tcp, seqnum)) {
1847                 return (TBADSEQ);
1848         }
1849         return (0);
1850 }
1851 
1852 /*
1853  * Our client hereby directs us to reject the connection request
1854  * that tcp_input_listener() marked with 'seqnum'.  Rejection consists
1855  * of sending the appropriate RST, not an ICMP error.
1856  */
1857 void
1858 tcp_disconnect(tcp_t *tcp, mblk_t *mp)
1859 {
1860         t_scalar_t seqnum;
1861         int     error;
1862         conn_t  *connp = tcp->tcp_connp;
1863 
1864         ASSERT((uintptr_t)(mp->b_wptr - mp->b_rptr) <= (uintptr_t)INT_MAX);
1865         if ((mp->b_wptr - mp->b_rptr) < sizeof (struct T_discon_req)) {
1866                 tcp_err_ack(tcp, mp, TPROTO, 0);
1867                 return;
1868         }
1869         seqnum = ((struct T_discon_req *)mp->b_rptr)->SEQ_number;
1870         error = tcp_disconnect_common(tcp, seqnum);
1871         if (error != 0)
1872                 tcp_err_ack(tcp, mp, error, 0);
1873         else {
1874                 if (tcp->tcp_state >= TCPS_ESTABLISHED) {
1875                         /* Send M_FLUSH according to TPI */
1876                         (void) putnextctl1(connp->conn_rq, M_FLUSH, FLUSHRW);
1877                 }
1878                 mp = mi_tpi_ok_ack_alloc(mp);
1879                 if (mp != NULL)
1880                         putnext(connp->conn_rq, mp);
1881         }
1882 }
1883 
1884 /*
1885  * Handle reinitialization of a tcp structure.
1886  * Maintain "binding state" resetting the state to BOUND, LISTEN, or IDLE.
1887  */
1888 static void
1889 tcp_reinit(tcp_t *tcp)
1890 {
1891         mblk_t          *mp;
1892         tcp_stack_t     *tcps = tcp->tcp_tcps;
1893         conn_t          *connp  = tcp->tcp_connp;
1894         int32_t         oldstate;
1895 
1896         /* tcp_reinit should never be called for detached tcp_t's */
1897         ASSERT(tcp->tcp_listener == NULL);
1898         ASSERT((connp->conn_family == AF_INET &&
1899             connp->conn_ipversion == IPV4_VERSION) ||
1900             (connp->conn_family == AF_INET6 &&
1901             (connp->conn_ipversion == IPV4_VERSION ||
1902             connp->conn_ipversion == IPV6_VERSION)));
1903 
1904         /* Cancel outstanding timers */
1905         tcp_timers_stop(tcp);
1906 
1907         /*
1908          * Reset everything in the state vector, after updating global
1909          * MIB data from instance counters.
1910          */
1911         TCPS_UPDATE_MIB(tcps, tcpHCInSegs, tcp->tcp_ibsegs);
1912         tcp->tcp_ibsegs = 0;
1913         TCPS_UPDATE_MIB(tcps, tcpHCOutSegs, tcp->tcp_obsegs);
1914         tcp->tcp_obsegs = 0;
1915 
1916         tcp_close_mpp(&tcp->tcp_xmit_head);
1917         if (tcp->tcp_snd_zcopy_aware)
1918                 tcp_zcopy_notify(tcp);
1919         tcp->tcp_xmit_last = tcp->tcp_xmit_tail = NULL;
1920         tcp->tcp_unsent = tcp->tcp_xmit_tail_unsent = 0;
1921         mutex_enter(&tcp->tcp_non_sq_lock);
1922         if (tcp->tcp_flow_stopped &&
1923             TCP_UNSENT_BYTES(tcp) <= connp->conn_sndlowat) {
1924                 tcp_clrqfull(tcp);
1925         }
1926         mutex_exit(&tcp->tcp_non_sq_lock);
1927         tcp_close_mpp(&tcp->tcp_reass_head);
1928         tcp->tcp_reass_tail = NULL;
1929         if (tcp->tcp_rcv_list != NULL) {
1930                 /* Free b_next chain */
1931                 tcp_close_mpp(&tcp->tcp_rcv_list);
1932                 tcp->tcp_rcv_last_head = NULL;
1933                 tcp->tcp_rcv_last_tail = NULL;
1934                 tcp->tcp_rcv_cnt = 0;
1935         }
1936         tcp->tcp_rcv_last_tail = NULL;
1937 
1938         if ((mp = tcp->tcp_urp_mp) != NULL) {
1939                 freemsg(mp);
1940                 tcp->tcp_urp_mp = NULL;
1941         }
1942         if ((mp = tcp->tcp_urp_mark_mp) != NULL) {
1943                 freemsg(mp);
1944                 tcp->tcp_urp_mark_mp = NULL;
1945         }
1946         if (tcp->tcp_fused_sigurg_mp != NULL) {
1947                 ASSERT(!IPCL_IS_NONSTR(tcp->tcp_connp));
1948                 freeb(tcp->tcp_fused_sigurg_mp);
1949                 tcp->tcp_fused_sigurg_mp = NULL;
1950         }
1951         if (tcp->tcp_ordrel_mp != NULL) {
1952                 ASSERT(!IPCL_IS_NONSTR(tcp->tcp_connp));
1953                 freeb(tcp->tcp_ordrel_mp);
1954                 tcp->tcp_ordrel_mp = NULL;
1955         }
1956 
1957         /*
1958          * Following is a union with two members which are
1959          * identical types and size so the following cleanup
1960          * is enough.
1961          */
1962         tcp_close_mpp(&tcp->tcp_conn.tcp_eager_conn_ind);
1963 
1964         CL_INET_DISCONNECT(connp);
1965 
1966         /*
1967          * The connection can't be on the tcp_time_wait_head list
1968          * since it is not detached.
1969          */
1970         ASSERT(tcp->tcp_time_wait_next == NULL);
1971         ASSERT(tcp->tcp_time_wait_prev == NULL);
1972         ASSERT(tcp->tcp_time_wait_expire == 0);
1973 
1974         /*
1975          * Reset/preserve other values
1976          */
1977         tcp_reinit_values(tcp);
1978         ipcl_hash_remove(connp);
1979         /* Note that ixa_cred gets cleared in ixa_cleanup */
1980         ixa_cleanup(connp->conn_ixa);
1981         tcp_ipsec_cleanup(tcp);
1982 
1983         connp->conn_laddr_v6 = connp->conn_bound_addr_v6;
1984         connp->conn_saddr_v6 = connp->conn_bound_addr_v6;
1985         oldstate = tcp->tcp_state;
1986 
1987         if (tcp->tcp_conn_req_max != 0) {
1988                 /*
1989                  * This is the case when a TLI program uses the same
1990                  * transport end point to accept a connection.  This
1991                  * makes the TCP both a listener and acceptor.  When
1992                  * this connection is closed, we need to set the state
1993                  * back to TCPS_LISTEN.  Make sure that the eager list
1994                  * is reinitialized.
1995                  *
1996                  * Note that this stream is still bound to the four
1997                  * tuples of the previous connection in IP.  If a new
1998                  * SYN with different foreign address comes in, IP will
1999                  * not find it and will send it to the global queue.  In
2000                  * the global queue, TCP will do a tcp_lookup_listener()
2001                  * to find this stream.  This works because this stream
2002                  * is only removed from connected hash.
2003                  *
2004                  */
2005                 tcp->tcp_state = TCPS_LISTEN;
2006                 tcp->tcp_eager_next_q0 = tcp->tcp_eager_prev_q0 = tcp;
2007                 tcp->tcp_eager_next_drop_q0 = tcp;
2008                 tcp->tcp_eager_prev_drop_q0 = tcp;
2009                 /*
2010                  * Initially set conn_recv to tcp_input_listener_unbound to try
2011                  * to pick a good squeue for the listener when the first SYN
2012                  * arrives. tcp_input_listener_unbound sets it to
2013                  * tcp_input_listener on that first SYN.
2014                  */
2015                 connp->conn_recv = tcp_input_listener_unbound;
2016 
2017                 connp->conn_proto = IPPROTO_TCP;
2018                 connp->conn_faddr_v6 = ipv6_all_zeros;
2019                 connp->conn_fport = 0;
2020 
2021                 (void) ipcl_bind_insert(connp);
2022         } else {
2023                 tcp->tcp_state = TCPS_BOUND;
2024         }
2025 
2026         /*
2027          * Initialize to default values
2028          */
2029         tcp_init_values(tcp, NULL);
2030 
2031         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
2032             connp->conn_ixa, void, NULL, tcp_t *, tcp, void, NULL,
2033             int32_t, oldstate);
2034 
2035         ASSERT(tcp->tcp_ptpbhn != NULL);
2036         tcp->tcp_rwnd = connp->conn_rcvbuf;
2037         tcp->tcp_mss = connp->conn_ipversion != IPV4_VERSION ?
2038             tcps->tcps_mss_def_ipv6 : tcps->tcps_mss_def_ipv4;
2039 }
2040 
2041 /*
2042  * Force values to zero that need be zero.
2043  * Do not touch values asociated with the BOUND or LISTEN state
2044  * since the connection will end up in that state after the reinit.
2045  * NOTE: tcp_reinit_values MUST have a line for each field in the tcp_t
2046  * structure!
2047  */
2048 static void
2049 tcp_reinit_values(tcp_t *tcp)
2050 {
2051         tcp_stack_t     *tcps = tcp->tcp_tcps;
2052         conn_t          *connp = tcp->tcp_connp;
2053 
2054 #ifndef lint
2055 #define DONTCARE(x)
2056 #define PRESERVE(x)
2057 #else
2058 #define DONTCARE(x)     ((x) = (x))
2059 #define PRESERVE(x)     ((x) = (x))
2060 #endif  /* lint */
2061 
2062         PRESERVE(tcp->tcp_bind_hash_port);
2063         PRESERVE(tcp->tcp_bind_hash);
2064         PRESERVE(tcp->tcp_ptpbhn);
2065         PRESERVE(tcp->tcp_acceptor_hash);
2066         PRESERVE(tcp->tcp_ptpahn);
2067 
2068         /* Should be ASSERT NULL on these with new code! */
2069         ASSERT(tcp->tcp_time_wait_next == NULL);
2070         ASSERT(tcp->tcp_time_wait_prev == NULL);
2071         ASSERT(tcp->tcp_time_wait_expire == 0);
2072         PRESERVE(tcp->tcp_state);
2073         PRESERVE(connp->conn_rq);
2074         PRESERVE(connp->conn_wq);
2075 
2076         ASSERT(tcp->tcp_xmit_head == NULL);
2077         ASSERT(tcp->tcp_xmit_last == NULL);
2078         ASSERT(tcp->tcp_unsent == 0);
2079         ASSERT(tcp->tcp_xmit_tail == NULL);
2080         ASSERT(tcp->tcp_xmit_tail_unsent == 0);
2081 
2082         tcp->tcp_snxt = 0;                   /* Displayed in mib */
2083         tcp->tcp_suna = 0;                   /* Displayed in mib */
2084         tcp->tcp_swnd = 0;
2085         DONTCARE(tcp->tcp_cwnd);     /* Init in tcp_process_options */
2086 
2087         ASSERT(tcp->tcp_ibsegs == 0);
2088         ASSERT(tcp->tcp_obsegs == 0);
2089 
2090         if (connp->conn_ht_iphc != NULL) {
2091                 kmem_free(connp->conn_ht_iphc, connp->conn_ht_iphc_allocated);
2092                 connp->conn_ht_iphc = NULL;
2093                 connp->conn_ht_iphc_allocated = 0;
2094                 connp->conn_ht_iphc_len = 0;
2095                 connp->conn_ht_ulp = NULL;
2096                 connp->conn_ht_ulp_len = 0;
2097                 tcp->tcp_ipha = NULL;
2098                 tcp->tcp_ip6h = NULL;
2099                 tcp->tcp_tcpha = NULL;
2100         }
2101 
2102         /* We clear any IP_OPTIONS and extension headers */
2103         ip_pkt_free(&connp->conn_xmit_ipp);
2104 
2105         DONTCARE(tcp->tcp_naglim);           /* Init in tcp_init_values */
2106         DONTCARE(tcp->tcp_ipha);
2107         DONTCARE(tcp->tcp_ip6h);
2108         DONTCARE(tcp->tcp_tcpha);
2109         tcp->tcp_valid_bits = 0;
2110 
2111         DONTCARE(tcp->tcp_timer_backoff);    /* Init in tcp_init_values */
2112         DONTCARE(tcp->tcp_last_recv_time);   /* Init in tcp_init_values */
2113         tcp->tcp_last_rcv_lbolt = 0;
2114 
2115         tcp->tcp_init_cwnd = 0;
2116 
2117         tcp->tcp_urp_last_valid = 0;
2118         tcp->tcp_hard_binding = 0;
2119 
2120         tcp->tcp_fin_acked = 0;
2121         tcp->tcp_fin_rcvd = 0;
2122         tcp->tcp_fin_sent = 0;
2123         tcp->tcp_ordrel_done = 0;
2124 
2125         tcp->tcp_detached = 0;
2126 
2127         tcp->tcp_snd_ws_ok = B_FALSE;
2128         tcp->tcp_snd_ts_ok = B_FALSE;
2129         tcp->tcp_zero_win_probe = 0;
2130 
2131         tcp->tcp_loopback = 0;
2132         tcp->tcp_localnet = 0;
2133         tcp->tcp_syn_defense = 0;
2134         tcp->tcp_set_timer = 0;
2135 
2136         tcp->tcp_active_open = 0;
2137         tcp->tcp_rexmit = B_FALSE;
2138         tcp->tcp_xmit_zc_clean = B_FALSE;
2139 
2140         tcp->tcp_snd_sack_ok = B_FALSE;
2141         tcp->tcp_hwcksum = B_FALSE;
2142 
2143         DONTCARE(tcp->tcp_maxpsz_multiplier);        /* Init in tcp_init_values */
2144 
2145         tcp->tcp_conn_def_q0 = 0;
2146         tcp->tcp_ip_forward_progress = B_FALSE;
2147         tcp->tcp_ecn_ok = B_FALSE;
2148 
2149         tcp->tcp_cwr = B_FALSE;
2150         tcp->tcp_ecn_echo_on = B_FALSE;
2151         tcp->tcp_is_wnd_shrnk = B_FALSE;
2152 
2153         TCP_NOTSACK_REMOVE_ALL(tcp->tcp_notsack_list, tcp);
2154         bzero(&tcp->tcp_sack_info, sizeof (tcp_sack_info_t));
2155 
2156         tcp->tcp_rcv_ws = 0;
2157         tcp->tcp_snd_ws = 0;
2158         tcp->tcp_ts_recent = 0;
2159         tcp->tcp_rnxt = 0;                   /* Displayed in mib */
2160         DONTCARE(tcp->tcp_rwnd);             /* Set in tcp_reinit() */
2161         tcp->tcp_initial_pmtu = 0;
2162 
2163         ASSERT(tcp->tcp_reass_head == NULL);
2164         ASSERT(tcp->tcp_reass_tail == NULL);
2165 
2166         tcp->tcp_cwnd_cnt = 0;
2167 
2168         ASSERT(tcp->tcp_rcv_list == NULL);
2169         ASSERT(tcp->tcp_rcv_last_head == NULL);
2170         ASSERT(tcp->tcp_rcv_last_tail == NULL);
2171         ASSERT(tcp->tcp_rcv_cnt == 0);
2172 
2173         DONTCARE(tcp->tcp_cwnd_ssthresh); /* Init in tcp_set_destination */
2174         DONTCARE(tcp->tcp_cwnd_max);         /* Init in tcp_init_values */
2175         tcp->tcp_csuna = 0;
2176 
2177         tcp->tcp_rto = 0;                    /* Displayed in MIB */
2178         DONTCARE(tcp->tcp_rtt_sa);           /* Init in tcp_init_values */
2179         DONTCARE(tcp->tcp_rtt_sd);           /* Init in tcp_init_values */
2180         tcp->tcp_rtt_update = 0;
2181 
2182         DONTCARE(tcp->tcp_swl1); /* Init in case TCPS_LISTEN/TCPS_SYN_SENT */
2183         DONTCARE(tcp->tcp_swl2); /* Init in case TCPS_LISTEN/TCPS_SYN_SENT */
2184 
2185         tcp->tcp_rack = 0;                   /* Displayed in mib */
2186         tcp->tcp_rack_cnt = 0;
2187         tcp->tcp_rack_cur_max = 0;
2188         tcp->tcp_rack_abs_max = 0;
2189 
2190         tcp->tcp_max_swnd = 0;
2191 
2192         ASSERT(tcp->tcp_listener == NULL);
2193 
2194         DONTCARE(tcp->tcp_irs);                      /* tcp_valid_bits cleared */
2195         DONTCARE(tcp->tcp_iss);                      /* tcp_valid_bits cleared */
2196         DONTCARE(tcp->tcp_fss);                      /* tcp_valid_bits cleared */
2197         DONTCARE(tcp->tcp_urg);                      /* tcp_valid_bits cleared */
2198 
2199         ASSERT(tcp->tcp_conn_req_cnt_q == 0);
2200         ASSERT(tcp->tcp_conn_req_cnt_q0 == 0);
2201         PRESERVE(tcp->tcp_conn_req_max);
2202         PRESERVE(tcp->tcp_conn_req_seqnum);
2203 
2204         DONTCARE(tcp->tcp_first_timer_threshold); /* Init in tcp_init_values */
2205         DONTCARE(tcp->tcp_second_timer_threshold); /* Init in tcp_init_values */
2206         DONTCARE(tcp->tcp_first_ctimer_threshold); /* Init in tcp_init_values */
2207         DONTCARE(tcp->tcp_second_ctimer_threshold); /* in tcp_init_values */
2208 
2209         DONTCARE(tcp->tcp_urp_last); /* tcp_urp_last_valid is cleared */
2210         ASSERT(tcp->tcp_urp_mp == NULL);
2211         ASSERT(tcp->tcp_urp_mark_mp == NULL);
2212         ASSERT(tcp->tcp_fused_sigurg_mp == NULL);
2213 
2214         ASSERT(tcp->tcp_eager_next_q == NULL);
2215         ASSERT(tcp->tcp_eager_last_q == NULL);
2216         ASSERT((tcp->tcp_eager_next_q0 == NULL &&
2217             tcp->tcp_eager_prev_q0 == NULL) ||
2218             tcp->tcp_eager_next_q0 == tcp->tcp_eager_prev_q0);
2219         ASSERT(tcp->tcp_conn.tcp_eager_conn_ind == NULL);
2220 
2221         ASSERT((tcp->tcp_eager_next_drop_q0 == NULL &&
2222             tcp->tcp_eager_prev_drop_q0 == NULL) ||
2223             tcp->tcp_eager_next_drop_q0 == tcp->tcp_eager_prev_drop_q0);
2224 
2225         DONTCARE(tcp->tcp_ka_rinterval);     /* Init in tcp_init_values */
2226         DONTCARE(tcp->tcp_ka_abort_thres);   /* Init in tcp_init_values */
2227         DONTCARE(tcp->tcp_ka_cnt);           /* Init in tcp_init_values */
2228 
2229         tcp->tcp_client_errno = 0;
2230 
2231         DONTCARE(connp->conn_sum);           /* Init in tcp_init_values */
2232 
2233         connp->conn_faddr_v6 = ipv6_all_zeros;       /* Displayed in MIB */
2234 
2235         PRESERVE(connp->conn_bound_addr_v6);
2236         tcp->tcp_last_sent_len = 0;
2237         tcp->tcp_dupack_cnt = 0;
2238 
2239         connp->conn_fport = 0;                       /* Displayed in MIB */
2240         PRESERVE(connp->conn_lport);
2241 
2242         PRESERVE(tcp->tcp_acceptor_lockp);
2243 
2244         ASSERT(tcp->tcp_ordrel_mp == NULL);
2245         PRESERVE(tcp->tcp_acceptor_id);
2246         DONTCARE(tcp->tcp_ipsec_overhead);
2247 
2248         PRESERVE(connp->conn_family);
2249         /* Remove any remnants of mapped address binding */
2250         if (connp->conn_family == AF_INET6) {
2251                 connp->conn_ipversion = IPV6_VERSION;
2252                 tcp->tcp_mss = tcps->tcps_mss_def_ipv6;
2253         } else {
2254                 connp->conn_ipversion = IPV4_VERSION;
2255                 tcp->tcp_mss = tcps->tcps_mss_def_ipv4;
2256         }
2257 
2258         connp->conn_bound_if = 0;
2259         connp->conn_recv_ancillary.crb_all = 0;
2260         tcp->tcp_recvifindex = 0;
2261         tcp->tcp_recvhops = 0;
2262         tcp->tcp_closed = 0;
2263         if (tcp->tcp_hopopts != NULL) {
2264                 mi_free(tcp->tcp_hopopts);
2265                 tcp->tcp_hopopts = NULL;
2266                 tcp->tcp_hopoptslen = 0;
2267         }
2268         ASSERT(tcp->tcp_hopoptslen == 0);
2269         if (tcp->tcp_dstopts != NULL) {
2270                 mi_free(tcp->tcp_dstopts);
2271                 tcp->tcp_dstopts = NULL;
2272                 tcp->tcp_dstoptslen = 0;
2273         }
2274         ASSERT(tcp->tcp_dstoptslen == 0);
2275         if (tcp->tcp_rthdrdstopts != NULL) {
2276                 mi_free(tcp->tcp_rthdrdstopts);
2277                 tcp->tcp_rthdrdstopts = NULL;
2278                 tcp->tcp_rthdrdstoptslen = 0;
2279         }
2280         ASSERT(tcp->tcp_rthdrdstoptslen == 0);
2281         if (tcp->tcp_rthdr != NULL) {
2282                 mi_free(tcp->tcp_rthdr);
2283                 tcp->tcp_rthdr = NULL;
2284                 tcp->tcp_rthdrlen = 0;
2285         }
2286         ASSERT(tcp->tcp_rthdrlen == 0);
2287 
2288         /* Reset fusion-related fields */
2289         tcp->tcp_fused = B_FALSE;
2290         tcp->tcp_unfusable = B_FALSE;
2291         tcp->tcp_fused_sigurg = B_FALSE;
2292         tcp->tcp_loopback_peer = NULL;
2293 
2294         tcp->tcp_lso = B_FALSE;
2295 
2296         tcp->tcp_in_ack_unsent = 0;
2297         tcp->tcp_cork = B_FALSE;
2298         tcp->tcp_tconnind_started = B_FALSE;
2299 
2300         PRESERVE(tcp->tcp_squeue_bytes);
2301 
2302         tcp->tcp_closemp_used = B_FALSE;
2303 
2304         PRESERVE(tcp->tcp_rsrv_mp);
2305         PRESERVE(tcp->tcp_rsrv_mp_lock);
2306 
2307 #ifdef DEBUG
2308         DONTCARE(tcp->tcmp_stk[0]);
2309 #endif
2310 
2311         PRESERVE(tcp->tcp_connid);
2312 
2313         ASSERT(tcp->tcp_listen_cnt == NULL);
2314         ASSERT(tcp->tcp_reass_tid == 0);
2315 
2316 #undef  DONTCARE
2317 #undef  PRESERVE
2318 }
2319 
2320 /*
2321  * Initialize the various fields in tcp_t.  If parent (the listener) is non
2322  * NULL, certain values will be inheritted from it.
2323  */
2324 void
2325 tcp_init_values(tcp_t *tcp, tcp_t *parent)
2326 {
2327         tcp_stack_t     *tcps = tcp->tcp_tcps;
2328         conn_t          *connp = tcp->tcp_connp;
2329 
2330         ASSERT((connp->conn_family == AF_INET &&
2331             connp->conn_ipversion == IPV4_VERSION) ||
2332             (connp->conn_family == AF_INET6 &&
2333             (connp->conn_ipversion == IPV4_VERSION ||
2334             connp->conn_ipversion == IPV6_VERSION)));
2335 
2336         if (parent == NULL) {
2337                 tcp->tcp_naglim = tcps->tcps_naglim_def;
2338 
2339                 tcp->tcp_rto_initial = tcps->tcps_rexmit_interval_initial;
2340                 tcp->tcp_rto_min = tcps->tcps_rexmit_interval_min;
2341                 tcp->tcp_rto_max = tcps->tcps_rexmit_interval_max;
2342 
2343                 tcp->tcp_first_ctimer_threshold =
2344                     tcps->tcps_ip_notify_cinterval;
2345                 tcp->tcp_second_ctimer_threshold =
2346                     tcps->tcps_ip_abort_cinterval;
2347                 tcp->tcp_first_timer_threshold = tcps->tcps_ip_notify_interval;
2348                 tcp->tcp_second_timer_threshold = tcps->tcps_ip_abort_interval;
2349 
2350                 tcp->tcp_fin_wait_2_flush_interval =
2351                     tcps->tcps_fin_wait_2_flush_interval;
2352 
2353                 tcp->tcp_ka_interval = tcps->tcps_keepalive_interval;
2354                 tcp->tcp_ka_abort_thres = tcps->tcps_keepalive_abort_interval;
2355                 tcp->tcp_ka_cnt = 0;
2356                 tcp->tcp_ka_rinterval = 0;
2357 
2358                 /*
2359                  * Default value of tcp_init_cwnd is 0, so no need to set here
2360                  * if parent is NULL.  But we need to inherit it from parent.
2361                  */
2362         } else {
2363                 /* Inherit various TCP parameters from the parent. */
2364                 tcp->tcp_naglim = parent->tcp_naglim;
2365 
2366                 tcp->tcp_rto_initial = parent->tcp_rto_initial;
2367                 tcp->tcp_rto_min = parent->tcp_rto_min;
2368                 tcp->tcp_rto_max = parent->tcp_rto_max;
2369 
2370                 tcp->tcp_first_ctimer_threshold =
2371                     parent->tcp_first_ctimer_threshold;
2372                 tcp->tcp_second_ctimer_threshold =
2373                     parent->tcp_second_ctimer_threshold;
2374                 tcp->tcp_first_timer_threshold =
2375                     parent->tcp_first_timer_threshold;
2376                 tcp->tcp_second_timer_threshold =
2377                     parent->tcp_second_timer_threshold;
2378 
2379                 tcp->tcp_fin_wait_2_flush_interval =
2380                     parent->tcp_fin_wait_2_flush_interval;
2381 
2382                 tcp->tcp_ka_interval = parent->tcp_ka_interval;
2383                 tcp->tcp_ka_abort_thres = parent->tcp_ka_abort_thres;
2384                 tcp->tcp_ka_cnt = parent->tcp_ka_cnt;
2385                 tcp->tcp_ka_rinterval = parent->tcp_ka_rinterval;
2386 
2387                 tcp->tcp_init_cwnd = parent->tcp_init_cwnd;
2388         }
2389 
2390         /*
2391          * Initialize tcp_rtt_sa and tcp_rtt_sd so that the calculated RTO
2392          * will be close to tcp_rexmit_interval_initial.  By doing this, we
2393          * allow the algorithm to adjust slowly to large fluctuations of RTT
2394          * during first few transmissions of a connection as seen in slow
2395          * links.
2396          */
2397         tcp->tcp_rtt_sa = MSEC2NSEC(tcp->tcp_rto_initial) << 2;
2398         tcp->tcp_rtt_sd = MSEC2NSEC(tcp->tcp_rto_initial) >> 1;
2399         tcp->tcp_rto = tcp_calculate_rto(tcp, tcps,
2400             tcps->tcps_conn_grace_period);
2401 
2402         tcp->tcp_timer_backoff = 0;
2403         tcp->tcp_ms_we_have_waited = 0;
2404         tcp->tcp_last_recv_time = ddi_get_lbolt();
2405         tcp->tcp_cwnd_max = tcps->tcps_cwnd_max_;
2406         tcp->tcp_cwnd_ssthresh = TCP_MAX_LARGEWIN;
2407 
2408         tcp->tcp_maxpsz_multiplier = tcps->tcps_maxpsz_multiplier;
2409 
2410         /* NOTE:  ISS is now set in tcp_set_destination(). */
2411 
2412         /* Reset fusion-related fields */
2413         tcp->tcp_fused = B_FALSE;
2414         tcp->tcp_unfusable = B_FALSE;
2415         tcp->tcp_fused_sigurg = B_FALSE;
2416         tcp->tcp_loopback_peer = NULL;
2417 
2418         /* We rebuild the header template on the next connect/conn_request */
2419 
2420         connp->conn_mlp_type = mlptSingle;
2421 
2422         /*
2423          * Init the window scale to the max so tcp_rwnd_set() won't pare
2424          * down tcp_rwnd. tcp_set_destination() will set the right value later.
2425          */
2426         tcp->tcp_rcv_ws = TCP_MAX_WINSHIFT;
2427         tcp->tcp_rwnd = connp->conn_rcvbuf;
2428 
2429         tcp->tcp_cork = B_FALSE;
2430         /*
2431          * Init the tcp_debug option if it wasn't already set.  This value
2432          * determines whether TCP
2433          * calls strlog() to print out debug messages.  Doing this
2434          * initialization here means that this value is not inherited thru
2435          * tcp_reinit().
2436          */
2437         if (!connp->conn_debug)
2438                 connp->conn_debug = tcps->tcps_dbg;
2439 }
2440 
2441 /*
2442  * Update the TCP connection according to change of PMTU.
2443  *
2444  * Path MTU might have changed by either increase or decrease, so need to
2445  * adjust the MSS based on the value of ixa_pmtu. No need to handle tiny
2446  * or negative MSS, since tcp_mss_set() will do it.
2447  */
2448 void
2449 tcp_update_pmtu(tcp_t *tcp, boolean_t decrease_only)
2450 {
2451         uint32_t        pmtu;
2452         int32_t         mss;
2453         conn_t          *connp = tcp->tcp_connp;
2454         ip_xmit_attr_t  *ixa = connp->conn_ixa;
2455         iaflags_t       ixaflags;
2456 
2457         if (tcp->tcp_tcps->tcps_ignore_path_mtu)
2458                 return;
2459 
2460         if (tcp->tcp_state < TCPS_ESTABLISHED)
2461                 return;
2462 
2463         /*
2464          * Always call ip_get_pmtu() to make sure that IP has updated
2465          * ixa_flags properly.
2466          */
2467         pmtu = ip_get_pmtu(ixa);
2468         ixaflags = ixa->ixa_flags;
2469 
2470         /*
2471          * Calculate the MSS by decreasing the PMTU by conn_ht_iphc_len and
2472          * IPsec overhead if applied. Make sure to use the most recent
2473          * IPsec information.
2474          */
2475         mss = pmtu - connp->conn_ht_iphc_len - conn_ipsec_length(connp);
2476 
2477         /*
2478          * Nothing to change, so just return.
2479          */
2480         if (mss == tcp->tcp_mss)
2481                 return;
2482 
2483         /*
2484          * Currently, for ICMP errors, only PMTU decrease is handled.
2485          */
2486         if (mss > tcp->tcp_mss && decrease_only)
2487                 return;
2488 
2489         DTRACE_PROBE2(tcp_update_pmtu, int32_t, tcp->tcp_mss, uint32_t, mss);
2490 
2491         /*
2492          * Update ixa_fragsize and ixa_pmtu.
2493          */
2494         ixa->ixa_fragsize = ixa->ixa_pmtu = pmtu;
2495 
2496         /*
2497          * Adjust MSS and all relevant variables.
2498          */
2499         tcp_mss_set(tcp, mss);
2500 
2501         /*
2502          * If the PMTU is below the min size maintained by IP, then ip_get_pmtu
2503          * has set IXAF_PMTU_TOO_SMALL and cleared IXAF_PMTU_IPV4_DF. Since TCP
2504          * has a (potentially different) min size we do the same. Make sure to
2505          * clear IXAF_DONTFRAG, which is used by IP to decide whether to
2506          * fragment the packet.
2507          *
2508          * LSO over IPv6 can not be fragmented. So need to disable LSO
2509          * when IPv6 fragmentation is needed.
2510          */
2511         if (mss < tcp->tcp_tcps->tcps_mss_min)
2512                 ixaflags |= IXAF_PMTU_TOO_SMALL;
2513 
2514         if (ixaflags & IXAF_PMTU_TOO_SMALL)
2515                 ixaflags &= ~(IXAF_DONTFRAG | IXAF_PMTU_IPV4_DF);
2516 
2517         if ((connp->conn_ipversion == IPV4_VERSION) &&
2518             !(ixaflags & IXAF_PMTU_IPV4_DF)) {
2519                 tcp->tcp_ipha->ipha_fragment_offset_and_flags = 0;
2520         }
2521         ixa->ixa_flags = ixaflags;
2522 }
2523 
2524 int
2525 tcp_maxpsz_set(tcp_t *tcp, boolean_t set_maxblk)
2526 {
2527         conn_t  *connp = tcp->tcp_connp;
2528         queue_t *q = connp->conn_rq;
2529         int32_t mss = tcp->tcp_mss;
2530         int     maxpsz;
2531 
2532         if (TCP_IS_DETACHED(tcp))
2533                 return (mss);
2534         if (tcp->tcp_fused) {
2535                 maxpsz = tcp_fuse_maxpsz(tcp);
2536                 mss = INFPSZ;
2537         } else if (tcp->tcp_maxpsz_multiplier == 0) {
2538                 /*
2539                  * Set the sd_qn_maxpsz according to the socket send buffer
2540                  * size, and sd_maxblk to INFPSZ (-1).  This will essentially
2541                  * instruct the stream head to copyin user data into contiguous
2542                  * kernel-allocated buffers without breaking it up into smaller
2543                  * chunks.  We round up the buffer size to the nearest SMSS.
2544                  */
2545                 maxpsz = MSS_ROUNDUP(connp->conn_sndbuf, mss);
2546                 mss = INFPSZ;
2547         } else {
2548                 /*
2549                  * Set sd_qn_maxpsz to approx half the (receivers) buffer
2550                  * (and a multiple of the mss).  This instructs the stream
2551                  * head to break down larger than SMSS writes into SMSS-
2552                  * size mblks, up to tcp_maxpsz_multiplier mblks at a time.
2553                  */
2554                 maxpsz = tcp->tcp_maxpsz_multiplier * mss;
2555                 if (maxpsz > connp->conn_sndbuf / 2) {
2556                         maxpsz = connp->conn_sndbuf / 2;
2557                         /* Round up to nearest mss */
2558                         maxpsz = MSS_ROUNDUP(maxpsz, mss);
2559                 }
2560         }
2561 
2562         (void) proto_set_maxpsz(q, connp, maxpsz);
2563         if (!(IPCL_IS_NONSTR(connp)))
2564                 connp->conn_wq->q_maxpsz = maxpsz;
2565         if (set_maxblk)
2566                 (void) proto_set_tx_maxblk(q, connp, mss);
2567         return (mss);
2568 }
2569 
2570 /* For /dev/tcp aka AF_INET open */
2571 static int
2572 tcp_openv4(queue_t *q, dev_t *devp, int flag, int sflag, cred_t *credp)
2573 {
2574         return (tcp_open(q, devp, flag, sflag, credp, B_FALSE));
2575 }
2576 
2577 /* For /dev/tcp6 aka AF_INET6 open */
2578 static int
2579 tcp_openv6(queue_t *q, dev_t *devp, int flag, int sflag, cred_t *credp)
2580 {
2581         return (tcp_open(q, devp, flag, sflag, credp, B_TRUE));
2582 }
2583 
2584 conn_t *
2585 tcp_create_common(cred_t *credp, boolean_t isv6, boolean_t issocket,
2586     int *errorp)
2587 {
2588         tcp_t           *tcp = NULL;
2589         conn_t          *connp;
2590         zoneid_t        zoneid;
2591         tcp_stack_t     *tcps;
2592         squeue_t        *sqp;
2593 
2594         ASSERT(errorp != NULL);
2595         /*
2596          * Find the proper zoneid and netstack.
2597          */
2598         /*
2599          * Special case for install: miniroot needs to be able to
2600          * access files via NFS as though it were always in the
2601          * global zone.
2602          */
2603         if (credp == kcred && nfs_global_client_only != 0) {
2604                 zoneid = GLOBAL_ZONEID;
2605                 tcps = netstack_find_by_stackid(GLOBAL_NETSTACKID)->
2606                     netstack_tcp;
2607                 ASSERT(tcps != NULL);
2608         } else {
2609                 netstack_t *ns;
2610                 int err;
2611 
2612                 if ((err = secpolicy_basic_net_access(credp)) != 0) {
2613                         *errorp = err;
2614                         return (NULL);
2615                 }
2616 
2617                 ns = netstack_find_by_cred(credp);
2618                 ASSERT(ns != NULL);
2619                 tcps = ns->netstack_tcp;
2620                 ASSERT(tcps != NULL);
2621 
2622                 /*
2623                  * For exclusive stacks we set the zoneid to zero
2624                  * to make TCP operate as if in the global zone.
2625                  */
2626                 if (tcps->tcps_netstack->netstack_stackid !=
2627                     GLOBAL_NETSTACKID)
2628                         zoneid = GLOBAL_ZONEID;
2629                 else
2630                         zoneid = crgetzoneid(credp);
2631         }
2632 
2633         sqp = IP_SQUEUE_GET((uint_t)gethrtime());
2634         connp = (conn_t *)tcp_get_conn(sqp, tcps);
2635         /*
2636          * Both tcp_get_conn and netstack_find_by_cred incremented refcnt,
2637          * so we drop it by one.
2638          */
2639         netstack_rele(tcps->tcps_netstack);
2640         if (connp == NULL) {
2641                 *errorp = ENOSR;
2642                 return (NULL);
2643         }
2644         ASSERT(connp->conn_ixa->ixa_protocol == connp->conn_proto);
2645 
2646         connp->conn_sqp = sqp;
2647         connp->conn_initial_sqp = connp->conn_sqp;
2648         connp->conn_ixa->ixa_sqp = connp->conn_sqp;
2649         tcp = connp->conn_tcp;
2650 
2651         /*
2652          * Besides asking IP to set the checksum for us, have conn_ip_output
2653          * to do the following checks when necessary:
2654          *
2655          * IXAF_VERIFY_SOURCE: drop packets when our outer source goes invalid
2656          * IXAF_VERIFY_PMTU: verify PMTU changes
2657          * IXAF_VERIFY_LSO: verify LSO capability changes
2658          */
2659         connp->conn_ixa->ixa_flags |= IXAF_SET_ULP_CKSUM | IXAF_VERIFY_SOURCE |
2660             IXAF_VERIFY_PMTU | IXAF_VERIFY_LSO;
2661 
2662         if (!tcps->tcps_dev_flow_ctl)
2663                 connp->conn_ixa->ixa_flags |= IXAF_NO_DEV_FLOW_CTL;
2664 
2665         if (isv6) {
2666                 connp->conn_ixa->ixa_src_preferences = IPV6_PREFER_SRC_DEFAULT;
2667                 connp->conn_ipversion = IPV6_VERSION;
2668                 connp->conn_family = AF_INET6;
2669                 tcp->tcp_mss = tcps->tcps_mss_def_ipv6;
2670                 connp->conn_default_ttl = tcps->tcps_ipv6_hoplimit;
2671         } else {
2672                 connp->conn_ipversion = IPV4_VERSION;
2673                 connp->conn_family = AF_INET;
2674                 tcp->tcp_mss = tcps->tcps_mss_def_ipv4;
2675                 connp->conn_default_ttl = tcps->tcps_ipv4_ttl;
2676         }
2677         connp->conn_xmit_ipp.ipp_unicast_hops = connp->conn_default_ttl;
2678 
2679         crhold(credp);
2680         connp->conn_cred = credp;
2681         connp->conn_cpid = curproc->p_pid;
2682         connp->conn_open_time = ddi_get_lbolt64();
2683 
2684         /* Cache things in the ixa without any refhold */
2685         ASSERT(!(connp->conn_ixa->ixa_free_flags & IXA_FREE_CRED));
2686         connp->conn_ixa->ixa_cred = credp;
2687         connp->conn_ixa->ixa_cpid = connp->conn_cpid;
2688 
2689         connp->conn_zoneid = zoneid;
2690         /* conn_allzones can not be set this early, hence no IPCL_ZONEID */
2691         connp->conn_ixa->ixa_zoneid = zoneid;
2692         connp->conn_mlp_type = mlptSingle;
2693         ASSERT(connp->conn_netstack == tcps->tcps_netstack);
2694         ASSERT(tcp->tcp_tcps == tcps);
2695 
2696         /*
2697          * If the caller has the process-wide flag set, then default to MAC
2698          * exempt mode.  This allows read-down to unlabeled hosts.
2699          */
2700         if (getpflags(NET_MAC_AWARE, credp) != 0)
2701                 connp->conn_mac_mode = CONN_MAC_AWARE;
2702 
2703         connp->conn_zone_is_global = (crgetzoneid(credp) == GLOBAL_ZONEID);
2704 
2705         if (issocket) {
2706                 tcp->tcp_issocket = 1;
2707         }
2708 
2709         connp->conn_rcvbuf = tcps->tcps_recv_hiwat;
2710         connp->conn_sndbuf = tcps->tcps_xmit_hiwat;
2711         if (tcps->tcps_snd_lowat_fraction != 0) {
2712                 connp->conn_sndlowat = connp->conn_sndbuf /
2713                     tcps->tcps_snd_lowat_fraction;
2714         } else {
2715                 connp->conn_sndlowat = tcps->tcps_xmit_lowat;
2716         }
2717         connp->conn_so_type = SOCK_STREAM;
2718         connp->conn_wroff = connp->conn_ht_iphc_allocated +
2719             tcps->tcps_wroff_xtra;
2720 
2721         SOCK_CONNID_INIT(tcp->tcp_connid);
2722         /* DTrace ignores this - it isn't a tcp:::state-change */
2723         tcp->tcp_state = TCPS_IDLE;
2724         tcp_init_values(tcp, NULL);
2725         return (connp);
2726 }
2727 
2728 static int
2729 tcp_open(queue_t *q, dev_t *devp, int flag, int sflag, cred_t *credp,
2730     boolean_t isv6)
2731 {
2732         tcp_t           *tcp = NULL;
2733         conn_t          *connp = NULL;
2734         int             err;
2735         vmem_t          *minor_arena = NULL;
2736         dev_t           conn_dev;
2737         boolean_t       issocket;
2738 
2739         if (q->q_ptr != NULL)
2740                 return (0);
2741 
2742         if (sflag == MODOPEN)
2743                 return (EINVAL);
2744 
2745         if ((ip_minor_arena_la != NULL) && (flag & SO_SOCKSTR) &&
2746             ((conn_dev = inet_minor_alloc(ip_minor_arena_la)) != 0)) {
2747                 minor_arena = ip_minor_arena_la;
2748         } else {
2749                 /*
2750                  * Either minor numbers in the large arena were exhausted
2751                  * or a non socket application is doing the open.
2752                  * Try to allocate from the small arena.
2753                  */
2754                 if ((conn_dev = inet_minor_alloc(ip_minor_arena_sa)) == 0) {
2755                         return (EBUSY);
2756                 }
2757                 minor_arena = ip_minor_arena_sa;
2758         }
2759 
2760         ASSERT(minor_arena != NULL);
2761 
2762         *devp = makedevice(getmajor(*devp), (minor_t)conn_dev);
2763 
2764         if (flag & SO_FALLBACK) {
2765                 /*
2766                  * Non streams socket needs a stream to fallback to
2767                  */
2768                 RD(q)->q_ptr = (void *)conn_dev;
2769                 WR(q)->q_qinfo = &tcp_fallback_sock_winit;
2770                 WR(q)->q_ptr = (void *)minor_arena;
2771                 qprocson(q);
2772                 return (0);
2773         } else if (flag & SO_ACCEPTOR) {
2774                 q->q_qinfo = &tcp_acceptor_rinit;
2775                 /*
2776                  * the conn_dev and minor_arena will be subsequently used by
2777                  * tcp_tli_accept() and tcp_tpi_close_accept() to figure out
2778                  * the minor device number for this connection from the q_ptr.
2779                  */
2780                 RD(q)->q_ptr = (void *)conn_dev;
2781                 WR(q)->q_qinfo = &tcp_acceptor_winit;
2782                 WR(q)->q_ptr = (void *)minor_arena;
2783                 qprocson(q);
2784                 return (0);
2785         }
2786 
2787         issocket = flag & SO_SOCKSTR;
2788         connp = tcp_create_common(credp, isv6, issocket, &err);
2789 
2790         if (connp == NULL) {
2791                 inet_minor_free(minor_arena, conn_dev);
2792                 q->q_ptr = WR(q)->q_ptr = NULL;
2793                 return (err);
2794         }
2795 
2796         connp->conn_rq = q;
2797         connp->conn_wq = WR(q);
2798         q->q_ptr = WR(q)->q_ptr = connp;
2799 
2800         connp->conn_dev = conn_dev;
2801         connp->conn_minor_arena = minor_arena;
2802 
2803         ASSERT(q->q_qinfo == &tcp_rinitv4 || q->q_qinfo == &tcp_rinitv6);
2804         ASSERT(WR(q)->q_qinfo == &tcp_winit);
2805 
2806         tcp = connp->conn_tcp;
2807 
2808         if (issocket) {
2809                 WR(q)->q_qinfo = &tcp_sock_winit;
2810         } else {
2811 #ifdef  _ILP32
2812                 tcp->tcp_acceptor_id = (t_uscalar_t)RD(q);
2813 #else
2814                 tcp->tcp_acceptor_id = conn_dev;
2815 #endif  /* _ILP32 */
2816                 tcp_acceptor_hash_insert(tcp->tcp_acceptor_id, tcp);
2817         }
2818 
2819         /*
2820          * Put the ref for TCP. Ref for IP was already put
2821          * by ipcl_conn_create. Also Make the conn_t globally
2822          * visible to walkers
2823          */
2824         mutex_enter(&connp->conn_lock);
2825         CONN_INC_REF_LOCKED(connp);
2826         ASSERT(connp->conn_ref == 2);
2827         connp->conn_state_flags &= ~CONN_INCIPIENT;
2828         mutex_exit(&connp->conn_lock);
2829 
2830         qprocson(q);
2831         return (0);
2832 }
2833 
2834 /*
2835  * Build/update the tcp header template (in conn_ht_iphc) based on
2836  * conn_xmit_ipp. The headers include ip6_t, any extension
2837  * headers, and the maximum size tcp header (to avoid reallocation
2838  * on the fly for additional tcp options).
2839  *
2840  * Assumes the caller has already set conn_{faddr,laddr,fport,lport,flowinfo}.
2841  * Returns failure if can't allocate memory.
2842  */
2843 int
2844 tcp_build_hdrs(tcp_t *tcp)
2845 {
2846         tcp_stack_t     *tcps = tcp->tcp_tcps;
2847         conn_t          *connp = tcp->tcp_connp;
2848         char            buf[TCP_MAX_HDR_LENGTH];
2849         uint_t          buflen;
2850         uint_t          ulplen = TCP_MIN_HEADER_LENGTH;
2851         uint_t          extralen = TCP_MAX_TCP_OPTIONS_LENGTH;
2852         tcpha_t         *tcpha;
2853         uint32_t        cksum;
2854         int             error;
2855 
2856         /*
2857          * We might be called after the connection is set up, and we might
2858          * have TS options already in the TCP header. Thus we  save any
2859          * existing tcp header.
2860          */
2861         buflen = connp->conn_ht_ulp_len;
2862         if (buflen != 0) {
2863                 bcopy(connp->conn_ht_ulp, buf, buflen);
2864                 extralen -= buflen - ulplen;
2865                 ulplen = buflen;
2866         }
2867 
2868         /* Grab lock to satisfy ASSERT; TCP is serialized using squeue */
2869         mutex_enter(&connp->conn_lock);
2870         error = conn_build_hdr_template(connp, ulplen, extralen,
2871             &connp->conn_laddr_v6, &connp->conn_faddr_v6, connp->conn_flowinfo);
2872         mutex_exit(&connp->conn_lock);
2873         if (error != 0)
2874                 return (error);
2875 
2876         /*
2877          * Any routing header/option has been massaged. The checksum difference
2878          * is stored in conn_sum for later use.
2879          */
2880         tcpha = (tcpha_t *)connp->conn_ht_ulp;
2881         tcp->tcp_tcpha = tcpha;
2882 
2883         /* restore any old tcp header */
2884         if (buflen != 0) {
2885                 bcopy(buf, connp->conn_ht_ulp, buflen);
2886         } else {
2887                 tcpha->tha_sum = 0;
2888                 tcpha->tha_urp = 0;
2889                 tcpha->tha_ack = 0;
2890                 tcpha->tha_offset_and_reserved = (5 << 4);
2891                 tcpha->tha_lport = connp->conn_lport;
2892                 tcpha->tha_fport = connp->conn_fport;
2893         }
2894 
2895         /*
2896          * IP wants our header length in the checksum field to
2897          * allow it to perform a single pseudo-header+checksum
2898          * calculation on behalf of TCP.
2899          * Include the adjustment for a source route once IP_OPTIONS is set.
2900          */
2901         cksum = sizeof (tcpha_t) + connp->conn_sum;
2902         cksum = (cksum >> 16) + (cksum & 0xFFFF);
2903         ASSERT(cksum < 0x10000);
2904         tcpha->tha_sum = htons(cksum);
2905 
2906         if (connp->conn_ipversion == IPV4_VERSION)
2907                 tcp->tcp_ipha = (ipha_t *)connp->conn_ht_iphc;
2908         else
2909                 tcp->tcp_ip6h = (ip6_t *)connp->conn_ht_iphc;
2910 
2911         if (connp->conn_ht_iphc_allocated + tcps->tcps_wroff_xtra >
2912             connp->conn_wroff) {
2913                 connp->conn_wroff = connp->conn_ht_iphc_allocated +
2914                     tcps->tcps_wroff_xtra;
2915                 (void) proto_set_tx_wroff(connp->conn_rq, connp,
2916                     connp->conn_wroff);
2917         }
2918         return (0);
2919 }
2920 
2921 /*
2922  * tcp_rwnd_set() is called to adjust the receive window to a desired value.
2923  * We do not allow the receive window to shrink.  After setting rwnd,
2924  * set the flow control hiwat of the stream.
2925  *
2926  * This function is called in 2 cases:
2927  *
2928  * 1) Before data transfer begins, in tcp_input_listener() for accepting a
2929  *    connection (passive open) and in tcp_input_data() for active connect.
2930  *    This is called after tcp_mss_set() when the desired MSS value is known.
2931  *    This makes sure that our window size is a mutiple of the other side's
2932  *    MSS.
2933  * 2) Handling SO_RCVBUF option.
2934  *
2935  * It is ASSUMED that the requested size is a multiple of the current MSS.
2936  *
2937  * XXX - Should allow a lower rwnd than tcp_recv_hiwat_minmss * mss if the
2938  * user requests so.
2939  */
2940 int
2941 tcp_rwnd_set(tcp_t *tcp, uint32_t rwnd)
2942 {
2943         uint32_t        mss = tcp->tcp_mss;
2944         uint32_t        old_max_rwnd;
2945         uint32_t        max_transmittable_rwnd;
2946         boolean_t       tcp_detached = TCP_IS_DETACHED(tcp);
2947         tcp_stack_t     *tcps = tcp->tcp_tcps;
2948         conn_t          *connp = tcp->tcp_connp;
2949 
2950         /*
2951          * Insist on a receive window that is at least
2952          * tcp_recv_hiwat_minmss * MSS (default 4 * MSS) to avoid
2953          * funny TCP interactions of Nagle algorithm, SWS avoidance
2954          * and delayed acknowledgement.
2955          */
2956         rwnd = MAX(rwnd, tcps->tcps_recv_hiwat_minmss * mss);
2957 
2958         if (tcp->tcp_fused) {
2959                 size_t sth_hiwat;
2960                 tcp_t *peer_tcp = tcp->tcp_loopback_peer;
2961 
2962                 ASSERT(peer_tcp != NULL);
2963                 sth_hiwat = tcp_fuse_set_rcv_hiwat(tcp, rwnd);
2964                 if (!tcp_detached) {
2965                         (void) proto_set_rx_hiwat(connp->conn_rq, connp,
2966                             sth_hiwat);
2967                         tcp_set_recv_threshold(tcp, sth_hiwat >> 3);
2968                 }
2969 
2970                 /* Caller could have changed tcp_rwnd; update tha_win */
2971                 if (tcp->tcp_tcpha != NULL) {
2972                         tcp->tcp_tcpha->tha_win =
2973                             htons(tcp->tcp_rwnd >> tcp->tcp_rcv_ws);
2974                 }
2975                 if ((tcp->tcp_rcv_ws > 0) && rwnd > tcp->tcp_cwnd_max)
2976                         tcp->tcp_cwnd_max = rwnd;
2977 
2978                 /*
2979                  * In the fusion case, the maxpsz stream head value of
2980                  * our peer is set according to its send buffer size
2981                  * and our receive buffer size; since the latter may
2982                  * have changed we need to update the peer's maxpsz.
2983                  */
2984                 (void) tcp_maxpsz_set(peer_tcp, B_TRUE);
2985                 return (sth_hiwat);
2986         }
2987 
2988         if (tcp_detached)
2989                 old_max_rwnd = tcp->tcp_rwnd;
2990         else
2991                 old_max_rwnd = connp->conn_rcvbuf;
2992 
2993 
2994         /*
2995          * If window size info has already been exchanged, TCP should not
2996          * shrink the window.  Shrinking window is doable if done carefully.
2997          * We may add that support later.  But so far there is not a real
2998          * need to do that.
2999          */
3000         if (rwnd < old_max_rwnd && tcp->tcp_state > TCPS_SYN_SENT) {
3001                 /* MSS may have changed, do a round up again. */
3002                 rwnd = MSS_ROUNDUP(old_max_rwnd, mss);
3003         }
3004 
3005         /*
3006          * tcp_rcv_ws starts with TCP_MAX_WINSHIFT so the following check
3007          * can be applied even before the window scale option is decided.
3008          */
3009         max_transmittable_rwnd = TCP_MAXWIN << tcp->tcp_rcv_ws;
3010         if (rwnd > max_transmittable_rwnd) {
3011                 rwnd = max_transmittable_rwnd -
3012                     (max_transmittable_rwnd % mss);
3013                 if (rwnd < mss)
3014                         rwnd = max_transmittable_rwnd;
3015                 /*
3016                  * If we're over the limit we may have to back down tcp_rwnd.
3017                  * The increment below won't work for us. So we set all three
3018                  * here and the increment below will have no effect.
3019                  */
3020                 tcp->tcp_rwnd = old_max_rwnd = rwnd;
3021         }
3022         if (tcp->tcp_localnet) {
3023                 tcp->tcp_rack_abs_max =
3024                     MIN(tcps->tcps_local_dacks_max, rwnd / mss / 2);
3025         } else {
3026                 /*
3027                  * For a remote host on a different subnet (through a router),
3028                  * we ack every other packet to be conforming to RFC1122.
3029                  * tcp_deferred_acks_max is default to 2.
3030                  */
3031                 tcp->tcp_rack_abs_max =
3032                     MIN(tcps->tcps_deferred_acks_max, rwnd / mss / 2);
3033         }
3034         if (tcp->tcp_rack_cur_max > tcp->tcp_rack_abs_max)
3035                 tcp->tcp_rack_cur_max = tcp->tcp_rack_abs_max;
3036         else
3037                 tcp->tcp_rack_cur_max = 0;
3038         /*
3039          * Increment the current rwnd by the amount the maximum grew (we
3040          * can not overwrite it since we might be in the middle of a
3041          * connection.)
3042          */
3043         tcp->tcp_rwnd += rwnd - old_max_rwnd;
3044         connp->conn_rcvbuf = rwnd;
3045 
3046         /* Are we already connected? */
3047         if (tcp->tcp_tcpha != NULL) {
3048                 tcp->tcp_tcpha->tha_win =
3049                     htons(tcp->tcp_rwnd >> tcp->tcp_rcv_ws);
3050         }
3051 
3052         if ((tcp->tcp_rcv_ws > 0) && rwnd > tcp->tcp_cwnd_max)
3053                 tcp->tcp_cwnd_max = rwnd;
3054 
3055         if (tcp_detached)
3056                 return (rwnd);
3057 
3058         tcp_set_recv_threshold(tcp, rwnd >> 3);
3059 
3060         (void) proto_set_rx_hiwat(connp->conn_rq, connp, rwnd);
3061         return (rwnd);
3062 }
3063 
3064 int
3065 tcp_do_unbind(conn_t *connp)
3066 {
3067         tcp_t *tcp = connp->conn_tcp;
3068         int32_t oldstate;
3069 
3070         switch (tcp->tcp_state) {
3071         case TCPS_BOUND:
3072         case TCPS_LISTEN:
3073                 break;
3074         default:
3075                 return (-TOUTSTATE);
3076         }
3077 
3078         /*
3079          * Need to clean up all the eagers since after the unbind, segments
3080          * will no longer be delivered to this listener stream.
3081          */
3082         mutex_enter(&tcp->tcp_eager_lock);
3083         if (tcp->tcp_conn_req_cnt_q0 != 0 || tcp->tcp_conn_req_cnt_q != 0) {
3084                 tcp_eager_cleanup(tcp, 0);
3085         }
3086         mutex_exit(&tcp->tcp_eager_lock);
3087 
3088         /* Clean up the listener connection counter if necessary. */
3089         if (tcp->tcp_listen_cnt != NULL)
3090                 TCP_DECR_LISTEN_CNT(tcp);
3091         connp->conn_laddr_v6 = ipv6_all_zeros;
3092         connp->conn_saddr_v6 = ipv6_all_zeros;
3093         tcp_bind_hash_remove(tcp);
3094         oldstate = tcp->tcp_state;
3095         tcp->tcp_state = TCPS_IDLE;
3096         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
3097             connp->conn_ixa, void, NULL, tcp_t *, tcp, void, NULL,
3098             int32_t, oldstate);
3099 
3100         ip_unbind(connp);
3101         bzero(&connp->conn_ports, sizeof (connp->conn_ports));
3102 
3103         return (0);
3104 }
3105 
3106 /*
3107  * Collect protocol properties to send to the upper handle.
3108  */
3109 void
3110 tcp_get_proto_props(tcp_t *tcp, struct sock_proto_props *sopp)
3111 {
3112         conn_t *connp = tcp->tcp_connp;
3113 
3114         sopp->sopp_flags = SOCKOPT_RCVHIWAT | SOCKOPT_MAXBLK | SOCKOPT_WROFF;
3115         sopp->sopp_maxblk = tcp_maxpsz_set(tcp, B_FALSE);
3116 
3117         sopp->sopp_rxhiwat = tcp->tcp_fused ?
3118             tcp_fuse_set_rcv_hiwat(tcp, connp->conn_rcvbuf) :
3119             connp->conn_rcvbuf;
3120         /*
3121          * Determine what write offset value to use depending on SACK and
3122          * whether the endpoint is fused or not.
3123          */
3124         if (tcp->tcp_fused) {
3125                 ASSERT(tcp->tcp_loopback);
3126                 ASSERT(tcp->tcp_loopback_peer != NULL);
3127                 /*
3128                  * For fused tcp loopback, set the stream head's write
3129                  * offset value to zero since we won't be needing any room
3130                  * for TCP/IP headers.  This would also improve performance
3131                  * since it would reduce the amount of work done by kmem.
3132                  * Non-fused tcp loopback case is handled separately below.
3133                  */
3134                 sopp->sopp_wroff = 0;
3135                 /*
3136                  * Update the peer's transmit parameters according to
3137                  * our recently calculated high water mark value.
3138                  */
3139                 (void) tcp_maxpsz_set(tcp->tcp_loopback_peer, B_TRUE);
3140         } else if (tcp->tcp_snd_sack_ok) {
3141                 sopp->sopp_wroff = connp->conn_ht_iphc_allocated +
3142                     (tcp->tcp_loopback ? 0 : tcp->tcp_tcps->tcps_wroff_xtra);
3143         } else {
3144                 sopp->sopp_wroff = connp->conn_ht_iphc_len +
3145                     (tcp->tcp_loopback ? 0 : tcp->tcp_tcps->tcps_wroff_xtra);
3146         }
3147 
3148         if (tcp->tcp_loopback) {
3149                 sopp->sopp_flags |= SOCKOPT_LOOPBACK;
3150                 sopp->sopp_loopback = B_TRUE;
3151         }
3152 }
3153 
3154 /*
3155  * Check the usability of ZEROCOPY. It's instead checking the flag set by IP.
3156  */
3157 boolean_t
3158 tcp_zcopy_check(tcp_t *tcp)
3159 {
3160         conn_t          *connp = tcp->tcp_connp;
3161         ip_xmit_attr_t  *ixa = connp->conn_ixa;
3162         boolean_t       zc_enabled = B_FALSE;
3163         tcp_stack_t     *tcps = tcp->tcp_tcps;
3164 
3165         if (do_tcpzcopy == 2)
3166                 zc_enabled = B_TRUE;
3167         else if ((do_tcpzcopy == 1) && (ixa->ixa_flags & IXAF_ZCOPY_CAPAB))
3168                 zc_enabled = B_TRUE;
3169 
3170         tcp->tcp_snd_zcopy_on = zc_enabled;
3171         if (!TCP_IS_DETACHED(tcp)) {
3172                 if (zc_enabled) {
3173                         ixa->ixa_flags |= IXAF_VERIFY_ZCOPY;
3174                         (void) proto_set_tx_copyopt(connp->conn_rq, connp,
3175                             ZCVMSAFE);
3176                         TCP_STAT(tcps, tcp_zcopy_on);
3177                 } else {
3178                         ixa->ixa_flags &= ~IXAF_VERIFY_ZCOPY;
3179                         (void) proto_set_tx_copyopt(connp->conn_rq, connp,
3180                             ZCVMUNSAFE);
3181                         TCP_STAT(tcps, tcp_zcopy_off);
3182                 }
3183         }
3184         return (zc_enabled);
3185 }
3186 
3187 /*
3188  * Backoff from a zero-copy message by copying data to a new allocated
3189  * message and freeing the original desballoca'ed segmapped message.
3190  *
3191  * This function is called by following two callers:
3192  * 1. tcp_timer: fix_xmitlist is set to B_TRUE, because it's safe to free
3193  *    the origial desballoca'ed message and notify sockfs. This is in re-
3194  *    transmit state.
3195  * 2. tcp_output: fix_xmitlist is set to B_FALSE. Flag STRUIO_ZCNOTIFY need
3196  *    to be copied to new message.
3197  */
3198 mblk_t *
3199 tcp_zcopy_backoff(tcp_t *tcp, mblk_t *bp, boolean_t fix_xmitlist)
3200 {
3201         mblk_t          *nbp;
3202         mblk_t          *head = NULL;
3203         mblk_t          *tail = NULL;
3204         tcp_stack_t     *tcps = tcp->tcp_tcps;
3205 
3206         ASSERT(bp != NULL);
3207         while (bp != NULL) {
3208                 if (IS_VMLOANED_MBLK(bp)) {
3209                         TCP_STAT(tcps, tcp_zcopy_backoff);
3210                         if ((nbp = copyb(bp)) == NULL) {
3211                                 tcp->tcp_xmit_zc_clean = B_FALSE;
3212                                 if (tail != NULL)
3213                                         tail->b_cont = bp;
3214                                 return ((head == NULL) ? bp : head);
3215                         }
3216 
3217                         if (bp->b_datap->db_struioflag & STRUIO_ZCNOTIFY) {
3218                                 if (fix_xmitlist)
3219                                         tcp_zcopy_notify(tcp);
3220                                 else
3221                                         nbp->b_datap->db_struioflag |=
3222                                             STRUIO_ZCNOTIFY;
3223                         }
3224                         nbp->b_cont = bp->b_cont;
3225 
3226                         /*
3227                          * Copy saved information and adjust tcp_xmit_tail
3228                          * if needed.
3229                          */
3230                         if (fix_xmitlist) {
3231                                 nbp->b_prev = bp->b_prev;
3232                                 nbp->b_next = bp->b_next;
3233 
3234                                 if (tcp->tcp_xmit_tail == bp)
3235                                         tcp->tcp_xmit_tail = nbp;
3236                         }
3237 
3238                         /* Free the original message. */
3239                         bp->b_prev = NULL;
3240                         bp->b_next = NULL;
3241                         freeb(bp);
3242 
3243                         bp = nbp;
3244                 }
3245 
3246                 if (head == NULL) {
3247                         head = bp;
3248                 }
3249                 if (tail == NULL) {
3250                         tail = bp;
3251                 } else {
3252                         tail->b_cont = bp;
3253                         tail = bp;
3254                 }
3255 
3256                 /* Move forward. */
3257                 bp = bp->b_cont;
3258         }
3259 
3260         if (fix_xmitlist) {
3261                 tcp->tcp_xmit_last = tail;
3262                 tcp->tcp_xmit_zc_clean = B_TRUE;
3263         }
3264 
3265         return (head);
3266 }
3267 
3268 void
3269 tcp_zcopy_notify(tcp_t *tcp)
3270 {
3271         struct stdata   *stp;
3272         conn_t          *connp;
3273 
3274         if (tcp->tcp_detached)
3275                 return;
3276         connp = tcp->tcp_connp;
3277         if (IPCL_IS_NONSTR(connp)) {
3278                 (*connp->conn_upcalls->su_zcopy_notify)
3279                     (connp->conn_upper_handle);
3280                 return;
3281         }
3282         stp = STREAM(connp->conn_rq);
3283         mutex_enter(&stp->sd_lock);
3284         stp->sd_flag |= STZCNOTIFY;
3285         cv_broadcast(&stp->sd_zcopy_wait);
3286         mutex_exit(&stp->sd_lock);
3287 }
3288 
3289 /*
3290  * Update the TCP connection according to change of LSO capability.
3291  */
3292 static void
3293 tcp_update_lso(tcp_t *tcp, ip_xmit_attr_t *ixa)
3294 {
3295         /*
3296          * We check against IPv4 header length to preserve the old behavior
3297          * of only enabling LSO when there are no IP options.
3298          * But this restriction might not be necessary at all. Before removing
3299          * it, need to verify how LSO is handled for source routing case, with
3300          * which IP does software checksum.
3301          *
3302          * For IPv6, whenever any extension header is needed, LSO is supressed.
3303          */
3304         if (ixa->ixa_ip_hdr_length != ((ixa->ixa_flags & IXAF_IS_IPV4) ?
3305             IP_SIMPLE_HDR_LENGTH : IPV6_HDR_LEN))
3306                 return;
3307 
3308         /*
3309          * Either the LSO capability newly became usable, or it has changed.
3310          */
3311         if (ixa->ixa_flags & IXAF_LSO_CAPAB) {
3312                 ill_lso_capab_t *lsoc = &ixa->ixa_lso_capab;
3313 
3314                 ASSERT(lsoc->ill_lso_max > 0);
3315                 tcp->tcp_lso_max = MIN(TCP_MAX_LSO_LENGTH, lsoc->ill_lso_max);
3316 
3317                 DTRACE_PROBE3(tcp_update_lso, boolean_t, tcp->tcp_lso,
3318                     boolean_t, B_TRUE, uint32_t, tcp->tcp_lso_max);
3319 
3320                 /*
3321                  * If LSO to be enabled, notify the STREAM header with larger
3322                  * data block.
3323                  */
3324                 if (!tcp->tcp_lso)
3325                         tcp->tcp_maxpsz_multiplier = 0;
3326 
3327                 tcp->tcp_lso = B_TRUE;
3328                 TCP_STAT(tcp->tcp_tcps, tcp_lso_enabled);
3329         } else { /* LSO capability is not usable any more. */
3330                 DTRACE_PROBE3(tcp_update_lso, boolean_t, tcp->tcp_lso,
3331                     boolean_t, B_FALSE, uint32_t, tcp->tcp_lso_max);
3332 
3333                 /*
3334                  * If LSO to be disabled, notify the STREAM header with smaller
3335                  * data block. And need to restore fragsize to PMTU.
3336                  */
3337                 if (tcp->tcp_lso) {
3338                         tcp->tcp_maxpsz_multiplier =
3339                             tcp->tcp_tcps->tcps_maxpsz_multiplier;
3340                         ixa->ixa_fragsize = ixa->ixa_pmtu;
3341                         tcp->tcp_lso = B_FALSE;
3342                         TCP_STAT(tcp->tcp_tcps, tcp_lso_disabled);
3343                 }
3344         }
3345 
3346         (void) tcp_maxpsz_set(tcp, B_TRUE);
3347 }
3348 
3349 /*
3350  * Update the TCP connection according to change of ZEROCOPY capability.
3351  */
3352 static void
3353 tcp_update_zcopy(tcp_t *tcp)
3354 {
3355         conn_t          *connp = tcp->tcp_connp;
3356         tcp_stack_t     *tcps = tcp->tcp_tcps;
3357 
3358         if (tcp->tcp_snd_zcopy_on) {
3359                 tcp->tcp_snd_zcopy_on = B_FALSE;
3360                 if (!TCP_IS_DETACHED(tcp)) {
3361                         (void) proto_set_tx_copyopt(connp->conn_rq, connp,
3362                             ZCVMUNSAFE);
3363                         TCP_STAT(tcps, tcp_zcopy_off);
3364                 }
3365         } else {
3366                 tcp->tcp_snd_zcopy_on = B_TRUE;
3367                 if (!TCP_IS_DETACHED(tcp)) {
3368                         (void) proto_set_tx_copyopt(connp->conn_rq, connp,
3369                             ZCVMSAFE);
3370                         TCP_STAT(tcps, tcp_zcopy_on);
3371                 }
3372         }
3373 }
3374 
3375 /*
3376  * Notify function registered with ip_xmit_attr_t. It's called in the squeue
3377  * so it's safe to update the TCP connection.
3378  */
3379 /* ARGSUSED1 */
3380 static void
3381 tcp_notify(void *arg, ip_xmit_attr_t *ixa, ixa_notify_type_t ntype,
3382     ixa_notify_arg_t narg)
3383 {
3384         tcp_t           *tcp = (tcp_t *)arg;
3385         conn_t          *connp = tcp->tcp_connp;
3386 
3387         switch (ntype) {
3388         case IXAN_LSO:
3389                 tcp_update_lso(tcp, connp->conn_ixa);
3390                 break;
3391         case IXAN_PMTU:
3392                 tcp_update_pmtu(tcp, B_FALSE);
3393                 break;
3394         case IXAN_ZCOPY:
3395                 tcp_update_zcopy(tcp);
3396                 break;
3397         default:
3398                 break;
3399         }
3400 }
3401 
3402 /*
3403  * The TCP write service routine should never be called...
3404  */
3405 /* ARGSUSED */
3406 static int
3407 tcp_wsrv(queue_t *q)
3408 {
3409         tcp_stack_t     *tcps = Q_TO_TCP(q)->tcp_tcps;
3410 
3411         TCP_STAT(tcps, tcp_wsrv_called);
3412         return (0);
3413 }
3414 
3415 /*
3416  * Hash list lookup routine for tcp_t structures.
3417  * Returns with a CONN_INC_REF tcp structure. Caller must do a CONN_DEC_REF.
3418  */
3419 tcp_t *
3420 tcp_acceptor_hash_lookup(t_uscalar_t id, tcp_stack_t *tcps)
3421 {
3422         tf_t    *tf;
3423         tcp_t   *tcp;
3424 
3425         tf = &tcps->tcps_acceptor_fanout[TCP_ACCEPTOR_HASH(id)];
3426         mutex_enter(&tf->tf_lock);
3427         for (tcp = tf->tf_tcp; tcp != NULL;
3428             tcp = tcp->tcp_acceptor_hash) {
3429                 if (tcp->tcp_acceptor_id == id) {
3430                         CONN_INC_REF(tcp->tcp_connp);
3431                         mutex_exit(&tf->tf_lock);
3432                         return (tcp);
3433                 }
3434         }
3435         mutex_exit(&tf->tf_lock);
3436         return (NULL);
3437 }
3438 
3439 /*
3440  * Hash list insertion routine for tcp_t structures.
3441  */
3442 void
3443 tcp_acceptor_hash_insert(t_uscalar_t id, tcp_t *tcp)
3444 {
3445         tf_t    *tf;
3446         tcp_t   **tcpp;
3447         tcp_t   *tcpnext;
3448         tcp_stack_t     *tcps = tcp->tcp_tcps;
3449 
3450         tf = &tcps->tcps_acceptor_fanout[TCP_ACCEPTOR_HASH(id)];
3451 
3452         if (tcp->tcp_ptpahn != NULL)
3453                 tcp_acceptor_hash_remove(tcp);
3454         tcpp = &tf->tf_tcp;
3455         mutex_enter(&tf->tf_lock);
3456         tcpnext = tcpp[0];
3457         if (tcpnext)
3458                 tcpnext->tcp_ptpahn = &tcp->tcp_acceptor_hash;
3459         tcp->tcp_acceptor_hash = tcpnext;
3460         tcp->tcp_ptpahn = tcpp;
3461         tcpp[0] = tcp;
3462         tcp->tcp_acceptor_lockp = &tf->tf_lock;       /* For tcp_*_hash_remove */
3463         mutex_exit(&tf->tf_lock);
3464 }
3465 
3466 /*
3467  * Hash list removal routine for tcp_t structures.
3468  */
3469 void
3470 tcp_acceptor_hash_remove(tcp_t *tcp)
3471 {
3472         tcp_t   *tcpnext;
3473         kmutex_t *lockp;
3474 
3475         /*
3476          * Extract the lock pointer in case there are concurrent
3477          * hash_remove's for this instance.
3478          */
3479         lockp = tcp->tcp_acceptor_lockp;
3480 
3481         if (tcp->tcp_ptpahn == NULL)
3482                 return;
3483 
3484         ASSERT(lockp != NULL);
3485         mutex_enter(lockp);
3486         if (tcp->tcp_ptpahn) {
3487                 tcpnext = tcp->tcp_acceptor_hash;
3488                 if (tcpnext) {
3489                         tcpnext->tcp_ptpahn = tcp->tcp_ptpahn;
3490                         tcp->tcp_acceptor_hash = NULL;
3491                 }
3492                 *tcp->tcp_ptpahn = tcpnext;
3493                 tcp->tcp_ptpahn = NULL;
3494         }
3495         mutex_exit(lockp);
3496         tcp->tcp_acceptor_lockp = NULL;
3497 }
3498 
3499 /*
3500  * Type three generator adapted from the random() function in 4.4 BSD:
3501  */
3502 
3503 /*
3504  * Copyright (c) 1983, 1993
3505  *      The Regents of the University of California.  All rights reserved.
3506  *
3507  * Redistribution and use in source and binary forms, with or without
3508  * modification, are permitted provided that the following conditions
3509  * are met:
3510  * 1. Redistributions of source code must retain the above copyright
3511  *    notice, this list of conditions and the following disclaimer.
3512  * 2. Redistributions in binary form must reproduce the above copyright
3513  *    notice, this list of conditions and the following disclaimer in the
3514  *    documentation and/or other materials provided with the distribution.
3515  * 3. All advertising materials mentioning features or use of this software
3516  *    must display the following acknowledgement:
3517  *      This product includes software developed by the University of
3518  *      California, Berkeley and its contributors.
3519  * 4. Neither the name of the University nor the names of its contributors
3520  *    may be used to endorse or promote products derived from this software
3521  *    without specific prior written permission.
3522  *
3523  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
3524  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
3525  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
3526  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
3527  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
3528  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
3529  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
3530  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
3531  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
3532  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
3533  * SUCH DAMAGE.
3534  */
3535 
3536 /* Type 3 -- x**31 + x**3 + 1 */
3537 #define DEG_3           31
3538 #define SEP_3           3
3539 
3540 
3541 /* Protected by tcp_random_lock */
3542 static int tcp_randtbl[DEG_3 + 1];
3543 
3544 static int *tcp_random_fptr = &tcp_randtbl[SEP_3 + 1];
3545 static int *tcp_random_rptr = &tcp_randtbl[1];
3546 
3547 static int *tcp_random_state = &tcp_randtbl[1];
3548 static int *tcp_random_end_ptr = &tcp_randtbl[DEG_3 + 1];
3549 
3550 kmutex_t tcp_random_lock;
3551 
3552 void
3553 tcp_random_init(void)
3554 {
3555         int i;
3556         hrtime_t hrt;
3557         time_t wallclock;
3558         uint64_t result;
3559 
3560         /*
3561          * Use high-res timer and current time for seed.  Gethrtime() returns
3562          * a longlong, which may contain resolution down to nanoseconds.
3563          * The current time will either be a 32-bit or a 64-bit quantity.
3564          * XOR the two together in a 64-bit result variable.
3565          * Convert the result to a 32-bit value by multiplying the high-order
3566          * 32-bits by the low-order 32-bits.
3567          */
3568 
3569         hrt = gethrtime();
3570         (void) drv_getparm(TIME, &wallclock);
3571         result = (uint64_t)wallclock ^ (uint64_t)hrt;
3572         mutex_enter(&tcp_random_lock);
3573         tcp_random_state[0] = ((result >> 32) & 0xffffffff) *
3574             (result & 0xffffffff);
3575 
3576         for (i = 1; i < DEG_3; i++)
3577                 tcp_random_state[i] = 1103515245 * tcp_random_state[i - 1]
3578                     + 12345;
3579         tcp_random_fptr = &tcp_random_state[SEP_3];
3580         tcp_random_rptr = &tcp_random_state[0];
3581         mutex_exit(&tcp_random_lock);
3582         for (i = 0; i < 10 * DEG_3; i++)
3583                 (void) tcp_random();
3584 }
3585 
3586 /*
3587  * tcp_random: Return a random number in the range [1 - (128K + 1)].
3588  * This range is selected to be approximately centered on TCP_ISS / 2,
3589  * and easy to compute. We get this value by generating a 32-bit random
3590  * number, selecting out the high-order 17 bits, and then adding one so
3591  * that we never return zero.
3592  */
3593 int
3594 tcp_random(void)
3595 {
3596         int i;
3597 
3598         mutex_enter(&tcp_random_lock);
3599         *tcp_random_fptr += *tcp_random_rptr;
3600 
3601         /*
3602          * The high-order bits are more random than the low-order bits,
3603          * so we select out the high-order 17 bits and add one so that
3604          * we never return zero.
3605          */
3606         i = ((*tcp_random_fptr >> 15) & 0x1ffff) + 1;
3607         if (++tcp_random_fptr >= tcp_random_end_ptr) {
3608                 tcp_random_fptr = tcp_random_state;
3609                 ++tcp_random_rptr;
3610         } else if (++tcp_random_rptr >= tcp_random_end_ptr)
3611                 tcp_random_rptr = tcp_random_state;
3612 
3613         mutex_exit(&tcp_random_lock);
3614         return (i);
3615 }
3616 
3617 /*
3618  * Split this function out so that if the secret changes, I'm okay.
3619  *
3620  * Initialize the tcp_iss_cookie and tcp_iss_key.
3621  */
3622 
3623 #define PASSWD_SIZE 16  /* MUST be multiple of 4 */
3624 
3625 void
3626 tcp_iss_key_init(uint8_t *phrase, int len, tcp_stack_t *tcps)
3627 {
3628         struct {
3629                 int32_t current_time;
3630                 uint32_t randnum;
3631                 uint16_t pad;
3632                 uint8_t ether[6];
3633                 uint8_t passwd[PASSWD_SIZE];
3634         } tcp_iss_cookie;
3635         time_t t;
3636 
3637         /*
3638          * Start with the current absolute time.
3639          */
3640         (void) drv_getparm(TIME, &t);
3641         tcp_iss_cookie.current_time = t;
3642 
3643         /*
3644          * XXX - Need a more random number per RFC 1750, not this crap.
3645          * OTOH, if what follows is pretty random, then I'm in better shape.
3646          */
3647         tcp_iss_cookie.randnum = (uint32_t)(gethrtime() + tcp_random());
3648         tcp_iss_cookie.pad = 0x365c;  /* Picked from HMAC pad values. */
3649 
3650         /*
3651          * The cpu_type_info is pretty non-random.  Ugggh.  It does serve
3652          * as a good template.
3653          */
3654         bcopy(&cpu_list->cpu_type_info, &tcp_iss_cookie.passwd,
3655             min(PASSWD_SIZE, sizeof (cpu_list->cpu_type_info)));
3656 
3657         /*
3658          * The pass-phrase.  Normally this is supplied by user-called NDD.
3659          */
3660         bcopy(phrase, &tcp_iss_cookie.passwd, min(PASSWD_SIZE, len));
3661 
3662         /*
3663          * See 4010593 if this section becomes a problem again,
3664          * but the local ethernet address is useful here.
3665          */
3666         (void) localetheraddr(NULL,
3667             (struct ether_addr *)&tcp_iss_cookie.ether);
3668 
3669         /*
3670          * Hash 'em all together.  The MD5Final is called per-connection.
3671          */
3672         mutex_enter(&tcps->tcps_iss_key_lock);
3673         MD5Init(&tcps->tcps_iss_key);
3674         MD5Update(&tcps->tcps_iss_key, (uchar_t *)&tcp_iss_cookie,
3675             sizeof (tcp_iss_cookie));
3676         mutex_exit(&tcps->tcps_iss_key_lock);
3677 }
3678 
3679 /*
3680  * Called by IP when IP is loaded into the kernel
3681  */
3682 void
3683 tcp_ddi_g_init(void)
3684 {
3685         tcp_timercache = kmem_cache_create("tcp_timercache",
3686             sizeof (tcp_timer_t) + sizeof (mblk_t), 0,
3687             NULL, NULL, NULL, NULL, NULL, 0);
3688 
3689         tcp_notsack_blk_cache = kmem_cache_create("tcp_notsack_blk_cache",
3690             sizeof (notsack_blk_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
3691 
3692         mutex_init(&tcp_random_lock, NULL, MUTEX_DEFAULT, NULL);
3693 
3694         /* Initialize the random number generator */
3695         tcp_random_init();
3696 
3697         /* A single callback independently of how many netstacks we have */
3698         ip_squeue_init(tcp_squeue_add);
3699 
3700         tcp_g_kstat = tcp_g_kstat_init(&tcp_g_statistics);
3701 
3702         tcp_squeue_flag = tcp_squeue_switch(tcp_squeue_wput);
3703 
3704         /*
3705          * We want to be informed each time a stack is created or
3706          * destroyed in the kernel, so we can maintain the
3707          * set of tcp_stack_t's.
3708          */
3709         netstack_register(NS_TCP, tcp_stack_init, NULL, tcp_stack_fini);
3710 }
3711 
3712 
3713 #define INET_NAME       "ip"
3714 
3715 /*
3716  * Initialize the TCP stack instance.
3717  */
3718 static void *
3719 tcp_stack_init(netstackid_t stackid, netstack_t *ns)
3720 {
3721         tcp_stack_t     *tcps;
3722         int             i;
3723         int             error = 0;
3724         major_t         major;
3725         size_t          arrsz;
3726 
3727         tcps = (tcp_stack_t *)kmem_zalloc(sizeof (*tcps), KM_SLEEP);
3728         tcps->tcps_netstack = ns;
3729 
3730         /* Initialize locks */
3731         mutex_init(&tcps->tcps_iss_key_lock, NULL, MUTEX_DEFAULT, NULL);
3732         mutex_init(&tcps->tcps_epriv_port_lock, NULL, MUTEX_DEFAULT, NULL);
3733 
3734         tcps->tcps_g_num_epriv_ports = TCP_NUM_EPRIV_PORTS;
3735         tcps->tcps_g_epriv_ports[0] = ULP_DEF_EPRIV_PORT1;
3736         tcps->tcps_g_epriv_ports[1] = ULP_DEF_EPRIV_PORT2;
3737         tcps->tcps_min_anonpriv_port = 512;
3738 
3739         tcps->tcps_bind_fanout = kmem_zalloc(sizeof (tf_t) *
3740             TCP_BIND_FANOUT_SIZE, KM_SLEEP);
3741         tcps->tcps_acceptor_fanout = kmem_zalloc(sizeof (tf_t) *
3742             TCP_ACCEPTOR_FANOUT_SIZE, KM_SLEEP);
3743 
3744         for (i = 0; i < TCP_BIND_FANOUT_SIZE; i++) {
3745                 mutex_init(&tcps->tcps_bind_fanout[i].tf_lock, NULL,
3746                     MUTEX_DEFAULT, NULL);
3747         }
3748 
3749         for (i = 0; i < TCP_ACCEPTOR_FANOUT_SIZE; i++) {
3750                 mutex_init(&tcps->tcps_acceptor_fanout[i].tf_lock, NULL,
3751                     MUTEX_DEFAULT, NULL);
3752         }
3753 
3754         /* TCP's IPsec code calls the packet dropper. */
3755         ip_drop_register(&tcps->tcps_dropper, "TCP IPsec policy enforcement");
3756 
3757         arrsz = tcp_propinfo_count * sizeof (mod_prop_info_t);
3758         tcps->tcps_propinfo_tbl = (mod_prop_info_t *)kmem_alloc(arrsz,
3759             KM_SLEEP);
3760         bcopy(tcp_propinfo_tbl, tcps->tcps_propinfo_tbl, arrsz);
3761 
3762         /*
3763          * Note: To really walk the device tree you need the devinfo
3764          * pointer to your device which is only available after probe/attach.
3765          * The following is safe only because it uses ddi_root_node()
3766          */
3767         tcp_max_optsize = optcom_max_optsize(tcp_opt_obj.odb_opt_des_arr,
3768             tcp_opt_obj.odb_opt_arr_cnt);
3769 
3770         /*
3771          * Initialize RFC 1948 secret values.  This will probably be reset once
3772          * by the boot scripts.
3773          *
3774          * Use NULL name, as the name is caught by the new lockstats.
3775          *
3776          * Initialize with some random, non-guessable string, like the global
3777          * T_INFO_ACK.
3778          */
3779 
3780         tcp_iss_key_init((uint8_t *)&tcp_g_t_info_ack,
3781             sizeof (tcp_g_t_info_ack), tcps);
3782 
3783         tcps->tcps_kstat = tcp_kstat2_init(stackid);
3784         tcps->tcps_mibkp = tcp_kstat_init(stackid);
3785 
3786         major = mod_name_to_major(INET_NAME);
3787         error = ldi_ident_from_major(major, &tcps->tcps_ldi_ident);
3788         ASSERT(error == 0);
3789         tcps->tcps_ixa_cleanup_mp = allocb_wait(0, BPRI_MED, STR_NOSIG, NULL);
3790         ASSERT(tcps->tcps_ixa_cleanup_mp != NULL);
3791         cv_init(&tcps->tcps_ixa_cleanup_ready_cv, NULL, CV_DEFAULT, NULL);
3792         cv_init(&tcps->tcps_ixa_cleanup_done_cv, NULL, CV_DEFAULT, NULL);
3793         mutex_init(&tcps->tcps_ixa_cleanup_lock, NULL, MUTEX_DEFAULT, NULL);
3794 
3795         mutex_init(&tcps->tcps_reclaim_lock, NULL, MUTEX_DEFAULT, NULL);
3796         tcps->tcps_reclaim = B_FALSE;
3797         tcps->tcps_reclaim_tid = 0;
3798         tcps->tcps_reclaim_period = tcps->tcps_rexmit_interval_max;
3799 
3800         /*
3801          * ncpus is the current number of CPUs, which can be bigger than
3802          * boot_ncpus.  But we don't want to use ncpus to allocate all the
3803          * tcp_stats_cpu_t at system boot up time since it will be 1.  While
3804          * we handle adding CPU in tcp_cpu_update(), it will be slow if
3805          * there are many CPUs as we will be adding them 1 by 1.
3806          *
3807          * Note that tcps_sc_cnt never decreases and the tcps_sc[x] pointers
3808          * are not freed until the stack is going away.  So there is no need
3809          * to grab a lock to access the per CPU tcps_sc[x] pointer.
3810          */
3811         mutex_enter(&cpu_lock);
3812         tcps->tcps_sc_cnt = MAX(ncpus, boot_ncpus);
3813         mutex_exit(&cpu_lock);
3814         tcps->tcps_sc = kmem_zalloc(max_ncpus  * sizeof (tcp_stats_cpu_t *),
3815             KM_SLEEP);
3816         for (i = 0; i < tcps->tcps_sc_cnt; i++) {
3817                 tcps->tcps_sc[i] = kmem_zalloc(sizeof (tcp_stats_cpu_t),
3818                     KM_SLEEP);
3819         }
3820 
3821         mutex_init(&tcps->tcps_listener_conf_lock, NULL, MUTEX_DEFAULT, NULL);
3822         list_create(&tcps->tcps_listener_conf, sizeof (tcp_listener_t),
3823             offsetof(tcp_listener_t, tl_link));
3824 
3825         return (tcps);
3826 }
3827 
3828 /*
3829  * Called when the IP module is about to be unloaded.
3830  */
3831 void
3832 tcp_ddi_g_destroy(void)
3833 {
3834         tcp_g_kstat_fini(tcp_g_kstat);
3835         tcp_g_kstat = NULL;
3836         bzero(&tcp_g_statistics, sizeof (tcp_g_statistics));
3837 
3838         mutex_destroy(&tcp_random_lock);
3839 
3840         kmem_cache_destroy(tcp_timercache);
3841         kmem_cache_destroy(tcp_notsack_blk_cache);
3842 
3843         netstack_unregister(NS_TCP);
3844 }
3845 
3846 /*
3847  * Free the TCP stack instance.
3848  */
3849 static void
3850 tcp_stack_fini(netstackid_t stackid, void *arg)
3851 {
3852         tcp_stack_t *tcps = (tcp_stack_t *)arg;
3853         int i;
3854 
3855         freeb(tcps->tcps_ixa_cleanup_mp);
3856         tcps->tcps_ixa_cleanup_mp = NULL;
3857         cv_destroy(&tcps->tcps_ixa_cleanup_ready_cv);
3858         cv_destroy(&tcps->tcps_ixa_cleanup_done_cv);
3859         mutex_destroy(&tcps->tcps_ixa_cleanup_lock);
3860 
3861         /*
3862          * Set tcps_reclaim to false tells tcp_reclaim_timer() not to restart
3863          * the timer.
3864          */
3865         mutex_enter(&tcps->tcps_reclaim_lock);
3866         tcps->tcps_reclaim = B_FALSE;
3867         mutex_exit(&tcps->tcps_reclaim_lock);
3868         if (tcps->tcps_reclaim_tid != 0)
3869                 (void) untimeout(tcps->tcps_reclaim_tid);
3870         mutex_destroy(&tcps->tcps_reclaim_lock);
3871 
3872         tcp_listener_conf_cleanup(tcps);
3873 
3874         for (i = 0; i < tcps->tcps_sc_cnt; i++)
3875                 kmem_free(tcps->tcps_sc[i], sizeof (tcp_stats_cpu_t));
3876         kmem_free(tcps->tcps_sc, max_ncpus * sizeof (tcp_stats_cpu_t *));
3877 
3878         kmem_free(tcps->tcps_propinfo_tbl,
3879             tcp_propinfo_count * sizeof (mod_prop_info_t));
3880         tcps->tcps_propinfo_tbl = NULL;
3881 
3882         for (i = 0; i < TCP_BIND_FANOUT_SIZE; i++) {
3883                 ASSERT(tcps->tcps_bind_fanout[i].tf_tcp == NULL);
3884                 mutex_destroy(&tcps->tcps_bind_fanout[i].tf_lock);
3885         }
3886 
3887         for (i = 0; i < TCP_ACCEPTOR_FANOUT_SIZE; i++) {
3888                 ASSERT(tcps->tcps_acceptor_fanout[i].tf_tcp == NULL);
3889                 mutex_destroy(&tcps->tcps_acceptor_fanout[i].tf_lock);
3890         }
3891 
3892         kmem_free(tcps->tcps_bind_fanout, sizeof (tf_t) * TCP_BIND_FANOUT_SIZE);
3893         tcps->tcps_bind_fanout = NULL;
3894 
3895         kmem_free(tcps->tcps_acceptor_fanout, sizeof (tf_t) *
3896             TCP_ACCEPTOR_FANOUT_SIZE);
3897         tcps->tcps_acceptor_fanout = NULL;
3898 
3899         mutex_destroy(&tcps->tcps_iss_key_lock);
3900         mutex_destroy(&tcps->tcps_epriv_port_lock);
3901 
3902         ip_drop_unregister(&tcps->tcps_dropper);
3903 
3904         tcp_kstat2_fini(stackid, tcps->tcps_kstat);
3905         tcps->tcps_kstat = NULL;
3906 
3907         tcp_kstat_fini(stackid, tcps->tcps_mibkp);
3908         tcps->tcps_mibkp = NULL;
3909 
3910         ldi_ident_release(tcps->tcps_ldi_ident);
3911         kmem_free(tcps, sizeof (*tcps));
3912 }
3913 
3914 /*
3915  * Generate ISS, taking into account NDD changes may happen halfway through.
3916  * (If the iss is not zero, set it.)
3917  */
3918 
3919 static void
3920 tcp_iss_init(tcp_t *tcp)
3921 {
3922         MD5_CTX context;
3923         struct { uint32_t ports; in6_addr_t src; in6_addr_t dst; } arg;
3924         uint32_t answer[4];
3925         tcp_stack_t     *tcps = tcp->tcp_tcps;
3926         conn_t          *connp = tcp->tcp_connp;
3927 
3928         tcps->tcps_iss_incr_extra += (tcps->tcps_iss_incr >> 1);
3929         tcp->tcp_iss = tcps->tcps_iss_incr_extra;
3930         switch (tcps->tcps_strong_iss) {
3931         case 2:
3932                 mutex_enter(&tcps->tcps_iss_key_lock);
3933                 context = tcps->tcps_iss_key;
3934                 mutex_exit(&tcps->tcps_iss_key_lock);
3935                 arg.ports = connp->conn_ports;
3936                 arg.src = connp->conn_laddr_v6;
3937                 arg.dst = connp->conn_faddr_v6;
3938                 MD5Update(&context, (uchar_t *)&arg, sizeof (arg));
3939                 MD5Final((uchar_t *)answer, &context);
3940                 tcp->tcp_iss += answer[0] ^ answer[1] ^ answer[2] ^ answer[3];
3941                 /*
3942                  * Now that we've hashed into a unique per-connection sequence
3943                  * space, add a random increment per strong_iss == 1.  So I
3944                  * guess we'll have to...
3945                  */
3946                 /* FALLTHRU */
3947         case 1:
3948                 tcp->tcp_iss += (gethrtime() >> ISS_NSEC_SHT) + tcp_random();
3949                 break;
3950         default:
3951                 tcp->tcp_iss += (uint32_t)gethrestime_sec() *
3952                     tcps->tcps_iss_incr;
3953                 break;
3954         }
3955         tcp->tcp_valid_bits = TCP_ISS_VALID;
3956         tcp->tcp_fss = tcp->tcp_iss - 1;
3957         tcp->tcp_suna = tcp->tcp_iss;
3958         tcp->tcp_snxt = tcp->tcp_iss + 1;
3959         tcp->tcp_rexmit_nxt = tcp->tcp_snxt;
3960         tcp->tcp_csuna = tcp->tcp_snxt;
3961 }
3962 
3963 /*
3964  * tcp_{set,clr}qfull() functions are used to either set or clear QFULL
3965  * on the specified backing STREAMS q. Note, the caller may make the
3966  * decision to call based on the tcp_t.tcp_flow_stopped value which
3967  * when check outside the q's lock is only an advisory check ...
3968  */
3969 void
3970 tcp_setqfull(tcp_t *tcp)
3971 {
3972         tcp_stack_t     *tcps = tcp->tcp_tcps;
3973         conn_t  *connp = tcp->tcp_connp;
3974 
3975         if (tcp->tcp_closed)
3976                 return;
3977 
3978         conn_setqfull(connp, &tcp->tcp_flow_stopped);
3979         if (tcp->tcp_flow_stopped)
3980                 TCP_STAT(tcps, tcp_flwctl_on);
3981 }
3982 
3983 void
3984 tcp_clrqfull(tcp_t *tcp)
3985 {
3986         conn_t  *connp = tcp->tcp_connp;
3987 
3988         if (tcp->tcp_closed)
3989                 return;
3990         conn_clrqfull(connp, &tcp->tcp_flow_stopped);
3991 }
3992 
3993 static int
3994 tcp_squeue_switch(int val)
3995 {
3996         int rval = SQ_FILL;
3997 
3998         switch (val) {
3999         case 1:
4000                 rval = SQ_NODRAIN;
4001                 break;
4002         case 2:
4003                 rval = SQ_PROCESS;
4004                 break;
4005         default:
4006                 break;
4007         }
4008         return (rval);
4009 }
4010 
4011 /*
4012  * This is called once for each squeue - globally for all stack
4013  * instances.
4014  */
4015 static void
4016 tcp_squeue_add(squeue_t *sqp)
4017 {
4018         tcp_squeue_priv_t *tcp_time_wait = kmem_zalloc(
4019             sizeof (tcp_squeue_priv_t), KM_SLEEP);
4020 
4021         *squeue_getprivate(sqp, SQPRIVATE_TCP) = (intptr_t)tcp_time_wait;
4022         if (tcp_free_list_max_cnt == 0) {
4023                 int tcp_ncpus = ((boot_max_ncpus == -1) ?
4024                     max_ncpus : boot_max_ncpus);
4025 
4026                 /*
4027                  * Limit number of entries to 1% of availble memory / tcp_ncpus
4028                  */
4029                 tcp_free_list_max_cnt = (freemem * PAGESIZE) /
4030                     (tcp_ncpus * sizeof (tcp_t) * 100);
4031         }
4032         tcp_time_wait->tcp_free_list_cnt = 0;
4033 }
4034 /*
4035  * Return unix error is tli error is TSYSERR, otherwise return a negative
4036  * tli error.
4037  */
4038 int
4039 tcp_do_bind(conn_t *connp, struct sockaddr *sa, socklen_t len, cred_t *cr,
4040     boolean_t bind_to_req_port_only)
4041 {
4042         int error;
4043         tcp_t *tcp = connp->conn_tcp;
4044 
4045         if (tcp->tcp_state >= TCPS_BOUND) {
4046                 if (connp->conn_debug) {
4047                         (void) strlog(TCP_MOD_ID, 0, 1, SL_ERROR|SL_TRACE,
4048                             "tcp_bind: bad state, %d", tcp->tcp_state);
4049                 }
4050                 return (-TOUTSTATE);
4051         }
4052 
4053         error = tcp_bind_check(connp, sa, len, cr, bind_to_req_port_only);
4054         if (error != 0)
4055                 return (error);
4056 
4057         ASSERT(tcp->tcp_state == TCPS_BOUND);
4058         tcp->tcp_conn_req_max = 0;
4059         return (0);
4060 }
4061 
4062 /*
4063  * If the return value from this function is positive, it's a UNIX error.
4064  * Otherwise, if it's negative, then the absolute value is a TLI error.
4065  * the TPI routine tcp_tpi_connect() is a wrapper function for this.
4066  */
4067 int
4068 tcp_do_connect(conn_t *connp, const struct sockaddr *sa, socklen_t len,
4069     cred_t *cr, pid_t pid)
4070 {
4071         tcp_t           *tcp = connp->conn_tcp;
4072         sin_t           *sin = (sin_t *)sa;
4073         sin6_t          *sin6 = (sin6_t *)sa;
4074         ipaddr_t        *dstaddrp;
4075         in_port_t       dstport;
4076         uint_t          srcid;
4077         int             error;
4078         uint32_t        mss;
4079         mblk_t          *syn_mp;
4080         tcp_stack_t     *tcps = tcp->tcp_tcps;
4081         int32_t         oldstate;
4082         ip_xmit_attr_t  *ixa = connp->conn_ixa;
4083 
4084         oldstate = tcp->tcp_state;
4085 
4086         switch (len) {
4087         default:
4088                 /*
4089                  * Should never happen
4090                  */
4091                 return (EINVAL);
4092 
4093         case sizeof (sin_t):
4094                 sin = (sin_t *)sa;
4095                 if (sin->sin_port == 0) {
4096                         return (-TBADADDR);
4097                 }
4098                 if (connp->conn_ipv6_v6only) {
4099                         return (EAFNOSUPPORT);
4100                 }
4101                 break;
4102 
4103         case sizeof (sin6_t):
4104                 sin6 = (sin6_t *)sa;
4105                 if (sin6->sin6_port == 0) {
4106                         return (-TBADADDR);
4107                 }
4108                 break;
4109         }
4110         /*
4111          * If we're connecting to an IPv4-mapped IPv6 address, we need to
4112          * make sure that the conn_ipversion is IPV4_VERSION.  We
4113          * need to this before we call tcp_bindi() so that the port lookup
4114          * code will look for ports in the correct port space (IPv4 and
4115          * IPv6 have separate port spaces).
4116          */
4117         if (connp->conn_family == AF_INET6 &&
4118             connp->conn_ipversion == IPV6_VERSION &&
4119             IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
4120                 if (connp->conn_ipv6_v6only)
4121                         return (EADDRNOTAVAIL);
4122 
4123                 connp->conn_ipversion = IPV4_VERSION;
4124         }
4125 
4126         switch (tcp->tcp_state) {
4127         case TCPS_LISTEN:
4128                 /*
4129                  * Listening sockets are not allowed to issue connect().
4130                  */
4131                 if (IPCL_IS_NONSTR(connp))
4132                         return (EOPNOTSUPP);
4133                 /* FALLTHRU */
4134         case TCPS_IDLE:
4135                 /*
4136                  * We support quick connect, refer to comments in
4137                  * tcp_connect_*()
4138                  */
4139                 /* FALLTHRU */
4140         case TCPS_BOUND:
4141                 break;
4142         default:
4143                 return (-TOUTSTATE);
4144         }
4145 
4146         /*
4147          * We update our cred/cpid based on the caller of connect
4148          */
4149         if (connp->conn_cred != cr) {
4150                 crhold(cr);
4151                 crfree(connp->conn_cred);
4152                 connp->conn_cred = cr;
4153         }
4154         connp->conn_cpid = pid;
4155 
4156         /* Cache things in the ixa without any refhold */
4157         ASSERT(!(ixa->ixa_free_flags & IXA_FREE_CRED));
4158         ixa->ixa_cred = cr;
4159         ixa->ixa_cpid = pid;
4160         if (is_system_labeled()) {
4161                 /* We need to restart with a label based on the cred */
4162                 ip_xmit_attr_restore_tsl(ixa, ixa->ixa_cred);
4163         }
4164 
4165         if (connp->conn_family == AF_INET6) {
4166                 if (!IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
4167                         error = tcp_connect_ipv6(tcp, &sin6->sin6_addr,
4168                             sin6->sin6_port, sin6->sin6_flowinfo,
4169                             sin6->__sin6_src_id, sin6->sin6_scope_id);
4170                 } else {
4171                         /*
4172                          * Destination adress is mapped IPv6 address.
4173                          * Source bound address should be unspecified or
4174                          * IPv6 mapped address as well.
4175                          */
4176                         if (!IN6_IS_ADDR_UNSPECIFIED(
4177                             &connp->conn_bound_addr_v6) &&
4178                             !IN6_IS_ADDR_V4MAPPED(&connp->conn_bound_addr_v6)) {
4179                                 return (EADDRNOTAVAIL);
4180                         }
4181                         dstaddrp = &V4_PART_OF_V6((sin6->sin6_addr));
4182                         dstport = sin6->sin6_port;
4183                         srcid = sin6->__sin6_src_id;
4184                         error = tcp_connect_ipv4(tcp, dstaddrp, dstport,
4185                             srcid);
4186                 }
4187         } else {
4188                 dstaddrp = &sin->sin_addr.s_addr;
4189                 dstport = sin->sin_port;
4190                 srcid = 0;
4191                 error = tcp_connect_ipv4(tcp, dstaddrp, dstport, srcid);
4192         }
4193 
4194         if (error != 0)
4195                 goto connect_failed;
4196 
4197         CL_INET_CONNECT(connp, B_TRUE, error);
4198         if (error != 0)
4199                 goto connect_failed;
4200 
4201         /* connect succeeded */
4202         TCPS_BUMP_MIB(tcps, tcpActiveOpens);
4203         tcp->tcp_active_open = 1;
4204 
4205         /*
4206          * tcp_set_destination() does not adjust for TCP/IP header length.
4207          */
4208         mss = tcp->tcp_mss - connp->conn_ht_iphc_len;
4209 
4210         /*
4211          * Just make sure our rwnd is at least rcvbuf * MSS large, and round up
4212          * to the nearest MSS.
4213          *
4214          * We do the round up here because we need to get the interface MTU
4215          * first before we can do the round up.
4216          */
4217         tcp->tcp_rwnd = connp->conn_rcvbuf;
4218         tcp->tcp_rwnd = MAX(MSS_ROUNDUP(tcp->tcp_rwnd, mss),
4219             tcps->tcps_recv_hiwat_minmss * mss);
4220         connp->conn_rcvbuf = tcp->tcp_rwnd;
4221         tcp_set_ws_value(tcp);
4222         tcp->tcp_tcpha->tha_win = htons(tcp->tcp_rwnd >> tcp->tcp_rcv_ws);
4223         if (tcp->tcp_rcv_ws > 0 || tcps->tcps_wscale_always)
4224                 tcp->tcp_snd_ws_ok = B_TRUE;
4225 
4226         /*
4227          * Set tcp_snd_ts_ok to true
4228          * so that tcp_xmit_mp will
4229          * include the timestamp
4230          * option in the SYN segment.
4231          */
4232         if (tcps->tcps_tstamp_always ||
4233             (tcp->tcp_rcv_ws && tcps->tcps_tstamp_if_wscale)) {
4234                 tcp->tcp_snd_ts_ok = B_TRUE;
4235         }
4236 
4237         /*
4238          * Note that tcp_snd_sack_ok can be set in tcp_set_destination() if
4239          * the SACK metric is set.  So here we just check the per stack SACK
4240          * permitted param.
4241          */
4242         if (tcps->tcps_sack_permitted == 2) {
4243                 ASSERT(tcp->tcp_num_sack_blk == 0);
4244                 ASSERT(tcp->tcp_notsack_list == NULL);
4245                 tcp->tcp_snd_sack_ok = B_TRUE;
4246         }
4247 
4248         /*
4249          * Should we use ECN?  Note that the current
4250          * default value (SunOS 5.9) of tcp_ecn_permitted
4251          * is 1.  The reason for doing this is that there
4252          * are equipments out there that will drop ECN
4253          * enabled IP packets.  Setting it to 1 avoids
4254          * compatibility problems.
4255          */
4256         if (tcps->tcps_ecn_permitted == 2)
4257                 tcp->tcp_ecn_ok = B_TRUE;
4258 
4259         /* Trace change from BOUND -> SYN_SENT here */
4260         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
4261             connp->conn_ixa, void, NULL, tcp_t *, tcp, void, NULL,
4262             int32_t, TCPS_BOUND);
4263 
4264         TCP_TIMER_RESTART(tcp, tcp->tcp_rto);
4265         syn_mp = tcp_xmit_mp(tcp, NULL, 0, NULL, NULL,
4266             tcp->tcp_iss, B_FALSE, NULL, B_FALSE);
4267         if (syn_mp != NULL) {
4268                 /*
4269                  * We must bump the generation before sending the syn
4270                  * to ensure that we use the right generation in case
4271                  * this thread issues a "connected" up call.
4272                  */
4273                 SOCK_CONNID_BUMP(tcp->tcp_connid);
4274                 /*
4275                  * DTrace sending the first SYN as a
4276                  * tcp:::connect-request event.
4277                  */
4278                 DTRACE_TCP5(connect__request, mblk_t *, NULL,
4279                     ip_xmit_attr_t *, connp->conn_ixa,
4280                     void_ip_t *, syn_mp->b_rptr, tcp_t *, tcp,
4281                     tcph_t *,
4282                     &syn_mp->b_rptr[connp->conn_ixa->ixa_ip_hdr_length]);
4283                 tcp_send_data(tcp, syn_mp);
4284         }
4285 
4286         if (tcp->tcp_conn.tcp_opts_conn_req != NULL)
4287                 tcp_close_mpp(&tcp->tcp_conn.tcp_opts_conn_req);
4288         return (0);
4289 
4290 connect_failed:
4291         connp->conn_faddr_v6 = ipv6_all_zeros;
4292         connp->conn_fport = 0;
4293         tcp->tcp_state = oldstate;
4294         if (tcp->tcp_conn.tcp_opts_conn_req != NULL)
4295                 tcp_close_mpp(&tcp->tcp_conn.tcp_opts_conn_req);
4296         return (error);
4297 }
4298 
4299 int
4300 tcp_do_listen(conn_t *connp, struct sockaddr *sa, socklen_t len,
4301     int backlog, cred_t *cr, boolean_t bind_to_req_port_only)
4302 {
4303         tcp_t           *tcp = connp->conn_tcp;
4304         int             error = 0;
4305         tcp_stack_t     *tcps = tcp->tcp_tcps;
4306         int32_t         oldstate;
4307 
4308         /* All Solaris components should pass a cred for this operation. */
4309         ASSERT(cr != NULL);
4310 
4311         if (tcp->tcp_state >= TCPS_BOUND) {
4312                 if ((tcp->tcp_state == TCPS_BOUND ||
4313                     tcp->tcp_state == TCPS_LISTEN) && backlog > 0) {
4314                         /*
4315                          * Handle listen() increasing backlog.
4316                          * This is more "liberal" then what the TPI spec
4317                          * requires but is needed to avoid a t_unbind
4318                          * when handling listen() since the port number
4319                          * might be "stolen" between the unbind and bind.
4320                          */
4321                         goto do_listen;
4322                 }
4323                 if (connp->conn_debug) {
4324                         (void) strlog(TCP_MOD_ID, 0, 1, SL_ERROR|SL_TRACE,
4325                             "tcp_listen: bad state, %d", tcp->tcp_state);
4326                 }
4327                 return (-TOUTSTATE);
4328         } else {
4329                 if (sa == NULL) {
4330                         sin6_t  addr;
4331                         sin_t *sin;
4332                         sin6_t *sin6;
4333 
4334                         ASSERT(IPCL_IS_NONSTR(connp));
4335                         /* Do an implicit bind: Request for a generic port. */
4336                         if (connp->conn_family == AF_INET) {
4337                                 len = sizeof (sin_t);
4338                                 sin = (sin_t *)&addr;
4339                                 *sin = sin_null;
4340                                 sin->sin_family = AF_INET;
4341                         } else {
4342                                 ASSERT(connp->conn_family == AF_INET6);
4343                                 len = sizeof (sin6_t);
4344                                 sin6 = (sin6_t *)&addr;
4345                                 *sin6 = sin6_null;
4346                                 sin6->sin6_family = AF_INET6;
4347                         }
4348                         sa = (struct sockaddr *)&addr;
4349                 }
4350 
4351                 error = tcp_bind_check(connp, sa, len, cr,
4352                     bind_to_req_port_only);
4353                 if (error)
4354                         return (error);
4355                 /* Fall through and do the fanout insertion */
4356         }
4357 
4358 do_listen:
4359         ASSERT(tcp->tcp_state == TCPS_BOUND || tcp->tcp_state == TCPS_LISTEN);
4360         tcp->tcp_conn_req_max = backlog;
4361         if (tcp->tcp_conn_req_max) {
4362                 if (tcp->tcp_conn_req_max < tcps->tcps_conn_req_min)
4363                         tcp->tcp_conn_req_max = tcps->tcps_conn_req_min;
4364                 if (tcp->tcp_conn_req_max > tcps->tcps_conn_req_max_q)
4365                         tcp->tcp_conn_req_max = tcps->tcps_conn_req_max_q;
4366                 /*
4367                  * If this is a listener, do not reset the eager list
4368                  * and other stuffs.  Note that we don't check if the
4369                  * existing eager list meets the new tcp_conn_req_max
4370                  * requirement.
4371                  */
4372                 if (tcp->tcp_state != TCPS_LISTEN) {
4373                         tcp->tcp_state = TCPS_LISTEN;
4374                         DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
4375                             connp->conn_ixa, void, NULL, tcp_t *, tcp,
4376                             void, NULL, int32_t, TCPS_BOUND);
4377                         /* Initialize the chain. Don't need the eager_lock */
4378                         tcp->tcp_eager_next_q0 = tcp->tcp_eager_prev_q0 = tcp;
4379                         tcp->tcp_eager_next_drop_q0 = tcp;
4380                         tcp->tcp_eager_prev_drop_q0 = tcp;
4381                         tcp->tcp_second_ctimer_threshold =
4382                             tcps->tcps_ip_abort_linterval;
4383                 }
4384         }
4385 
4386         /*
4387          * We need to make sure that the conn_recv is set to a non-null
4388          * value before we insert the conn into the classifier table.
4389          * This is to avoid a race with an incoming packet which does an
4390          * ipcl_classify().
4391          * We initially set it to tcp_input_listener_unbound to try to
4392          * pick a good squeue for the listener when the first SYN arrives.
4393          * tcp_input_listener_unbound sets it to tcp_input_listener on that
4394          * first SYN.
4395          */
4396         connp->conn_recv = tcp_input_listener_unbound;
4397 
4398         /* Insert the listener in the classifier table */
4399         error = ip_laddr_fanout_insert(connp);
4400         if (error != 0) {
4401                 /* Undo the bind - release the port number */
4402                 oldstate = tcp->tcp_state;
4403                 tcp->tcp_state = TCPS_IDLE;
4404                 DTRACE_TCP6(state__change, void, NULL, ip_xmit_attr_t *,
4405                     connp->conn_ixa, void, NULL, tcp_t *, tcp, void, NULL,
4406                     int32_t, oldstate);
4407                 connp->conn_bound_addr_v6 = ipv6_all_zeros;
4408 
4409                 connp->conn_laddr_v6 = ipv6_all_zeros;
4410                 connp->conn_saddr_v6 = ipv6_all_zeros;
4411                 connp->conn_ports = 0;
4412 
4413                 if (connp->conn_anon_port) {
4414                         zone_t          *zone;
4415 
4416                         zone = crgetzone(cr);
4417                         connp->conn_anon_port = B_FALSE;
4418                         (void) tsol_mlp_anon(zone, connp->conn_mlp_type,
4419                             connp->conn_proto, connp->conn_lport, B_FALSE);
4420                 }
4421                 connp->conn_mlp_type = mlptSingle;
4422 
4423                 tcp_bind_hash_remove(tcp);
4424                 return (error);
4425         } else {
4426                 /*
4427                  * If there is a connection limit, allocate and initialize
4428                  * the counter struct.  Note that since listen can be called
4429                  * multiple times, the struct may have been allready allocated.
4430                  */
4431                 if (!list_is_empty(&tcps->tcps_listener_conf) &&
4432                     tcp->tcp_listen_cnt == NULL) {
4433                         tcp_listen_cnt_t *tlc;
4434                         uint32_t ratio;
4435 
4436                         ratio = tcp_find_listener_conf(tcps,
4437                             ntohs(connp->conn_lport));
4438                         if (ratio != 0) {
4439                                 uint32_t mem_ratio, tot_buf;
4440 
4441                                 tlc = kmem_alloc(sizeof (tcp_listen_cnt_t),
4442                                     KM_SLEEP);
4443                                 /*
4444                                  * Calculate the connection limit based on
4445                                  * the configured ratio and maxusers.  Maxusers
4446                                  * are calculated based on memory size,
4447                                  * ~ 1 user per MB.  Note that the conn_rcvbuf
4448                                  * and conn_sndbuf may change after a
4449                                  * connection is accepted.  So what we have
4450                                  * is only an approximation.
4451                                  */
4452                                 if ((tot_buf = connp->conn_rcvbuf +
4453                                     connp->conn_sndbuf) < MB) {
4454                                         mem_ratio = MB / tot_buf;
4455                                         tlc->tlc_max = maxusers / ratio *
4456                                             mem_ratio;
4457                                 } else {
4458                                         mem_ratio = tot_buf / MB;
4459                                         tlc->tlc_max = maxusers / ratio /
4460                                             mem_ratio;
4461                                 }
4462                                 /* At least we should allow two connections! */
4463                                 if (tlc->tlc_max <= tcp_min_conn_listener)
4464                                         tlc->tlc_max = tcp_min_conn_listener;
4465                                 tlc->tlc_cnt = 1;
4466                                 tlc->tlc_drop = 0;
4467                                 tcp->tcp_listen_cnt = tlc;
4468                         }
4469                 }
4470         }
4471         return (error);
4472 }