1 /*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5 * Interface to packet compression for ssh.
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 */
13
14 #include "includes.h"
15 RCSID("$OpenBSD: compress.c,v 1.19 2002/03/18 17:31:54 provos Exp $");
16
17 #pragma ident "%Z%%M% %I% %E% SMI"
18
19 #include "log.h"
20 #include "buffer.h"
21 #include "zlib.h"
22 #include "compress.h"
23
24 z_stream incoming_stream;
25 z_stream outgoing_stream;
26 static int compress_init_send_called = 0;
27 static int compress_init_recv_called = 0;
28 static int inflate_failed = 0;
29 static int deflate_failed = 0;
30
31 /*
32 * Initializes compression; level is compression level from 1 to 9
33 * (as in gzip).
34 */
35
36 void
37 buffer_compress_init_send(int level)
38 {
39 if (compress_init_send_called == 1)
40 deflateEnd(&outgoing_stream);
41 compress_init_send_called = 1;
42 debug("Enabling compression at level %d.", level);
43 if (level < 1 || level > 9)
44 fatal("Bad compression level %d.", level);
45 deflateInit(&outgoing_stream, level);
46 }
47 void
48 buffer_compress_init_recv(void)
49 {
50 if (compress_init_recv_called == 1)
51 inflateEnd(&incoming_stream);
52 compress_init_recv_called = 1;
53 inflateInit(&incoming_stream);
54 }
55
56 /* Frees any data structures allocated for compression. */
57
58 void
59 buffer_compress_uninit(void)
60 {
61 debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
62 outgoing_stream.total_in, outgoing_stream.total_out,
63 outgoing_stream.total_in == 0 ? 0.0 :
64 (double) outgoing_stream.total_out / outgoing_stream.total_in);
65 debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
66 incoming_stream.total_out, incoming_stream.total_in,
67 incoming_stream.total_out == 0 ? 0.0 :
68 (double) incoming_stream.total_in / incoming_stream.total_out);
69 if (compress_init_recv_called == 1 && inflate_failed == 0)
70 inflateEnd(&incoming_stream);
71 if (compress_init_send_called == 1 && deflate_failed == 0)
72 deflateEnd(&outgoing_stream);
73 }
74
75 /*
76 * Compresses the contents of input_buffer into output_buffer. All packets
77 * compressed using this function will form a single compressed data stream;
78 * however, data will be flushed at the end of every call so that each
79 * output_buffer can be decompressed independently (but in the appropriate
80 * order since they together form a single compression stream) by the
81 * receiver. This appends the compressed data to the output buffer.
82 */
83
84 void
85 buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
86 {
87 u_char buf[4096];
88 int status;
89
90 /* This case is not handled below. */
91 if (buffer_len(input_buffer) == 0)
92 return;
93
94 /* Input is the contents of the input buffer. */
95 outgoing_stream.next_in = buffer_ptr(input_buffer);
96 outgoing_stream.avail_in = buffer_len(input_buffer);
97
98 /* Loop compressing until deflate() returns with avail_out != 0. */
99 do {
100 /* Set up fixed-size output buffer. */
101 outgoing_stream.next_out = buf;
102 outgoing_stream.avail_out = sizeof(buf);
103
104 /* Compress as much data into the buffer as possible. */
105 status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
106 switch (status) {
107 case Z_OK:
108 /* Append compressed data to output_buffer. */
109 buffer_append(output_buffer, buf,
110 sizeof(buf) - outgoing_stream.avail_out);
111 break;
112 default:
113 deflate_failed = 1;
114 fatal("buffer_compress: deflate returned %d", status);
115 /* NOTREACHED */
116 }
117 } while (outgoing_stream.avail_out == 0);
118 }
119
120 /*
121 * Uncompresses the contents of input_buffer into output_buffer. All packets
122 * uncompressed using this function will form a single compressed data
123 * stream; however, data will be flushed at the end of every call so that
124 * each output_buffer. This must be called for the same size units that the
125 * buffer_compress was called, and in the same order that buffers compressed
126 * with that. This appends the uncompressed data to the output buffer.
127 */
128
129 void
130 buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
131 {
132 u_char buf[4096];
133 int status;
134
135 incoming_stream.next_in = buffer_ptr(input_buffer);
136 incoming_stream.avail_in = buffer_len(input_buffer);
137
138 for (;;) {
139 /* Set up fixed-size output buffer. */
140 incoming_stream.next_out = buf;
141 incoming_stream.avail_out = sizeof(buf);
142
143 status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
144 switch (status) {
145 case Z_OK:
146 buffer_append(output_buffer, buf,
147 sizeof(buf) - incoming_stream.avail_out);
148 break;
149 case Z_BUF_ERROR:
150 /*
151 * Comments in zlib.h say that we should keep calling
152 * inflate() until we get an error. This appears to
153 * be the error that we get.
154 */
155 return;
156 default:
157 inflate_failed = 1;
158 fatal("buffer_uncompress: inflate returned %d", status);
159 /* NOTREACHED */
160 }
161 }
162 }