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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 1.15 2001/09/27 11:58:16 markus Exp $"); | |
16 | ||
17 | #include "log.h" | |
18 | #include "buffer.h" | |
19 | #include "zlib.h" | |
20 | #include "compress.h" | |
21 | ||
22 | static z_stream incoming_stream; | |
23 | static z_stream outgoing_stream; | |
24 | static int compress_init_send_called = 0; | |
25 | static int compress_init_recv_called = 0; | |
26 | ||
27 | /* | |
28 | * Initializes compression; level is compression level from 1 to 9 | |
29 | * (as in gzip). | |
30 | */ | |
31 | ||
32 | void | |
33 | buffer_compress_init_send(int level) | |
34 | { | |
35 | if (compress_init_send_called == 1) | |
36 | deflateEnd(&outgoing_stream); | |
37 | compress_init_send_called = 1; | |
38 | debug("Enabling compression at level %d.", level); | |
39 | if (level < 1 || level > 9) | |
40 | fatal("Bad compression level %d.", level); | |
41 | deflateInit(&outgoing_stream, level); | |
42 | } | |
43 | void | |
44 | buffer_compress_init_recv(void) | |
45 | { | |
46 | if (compress_init_recv_called == 1) | |
47 | inflateEnd(&incoming_stream); | |
48 | compress_init_recv_called = 1; | |
49 | inflateInit(&incoming_stream); | |
50 | } | |
51 | ||
52 | /* Frees any data structures allocated for compression. */ | |
53 | ||
54 | void | |
55 | buffer_compress_uninit(void) | |
56 | { | |
57 | debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f", | |
58 | outgoing_stream.total_in, outgoing_stream.total_out, | |
59 | outgoing_stream.total_in == 0 ? 0.0 : | |
60 | (double) outgoing_stream.total_out / outgoing_stream.total_in); | |
61 | debug("compress incoming: raw data %lu, compressed %lu, factor %.2f", | |
62 | incoming_stream.total_out, incoming_stream.total_in, | |
63 | incoming_stream.total_out == 0 ? 0.0 : | |
64 | (double) incoming_stream.total_in / incoming_stream.total_out); | |
65 | if (compress_init_recv_called == 1) | |
66 | inflateEnd(&incoming_stream); | |
67 | if (compress_init_send_called == 1) | |
68 | deflateEnd(&outgoing_stream); | |
69 | } | |
70 | ||
71 | /* | |
72 | * Compresses the contents of input_buffer into output_buffer. All packets | |
73 | * compressed using this function will form a single compressed data stream; | |
74 | * however, data will be flushed at the end of every call so that each | |
75 | * output_buffer can be decompressed independently (but in the appropriate | |
76 | * order since they together form a single compression stream) by the | |
77 | * receiver. This appends the compressed data to the output buffer. | |
78 | */ | |
79 | ||
80 | void | |
81 | buffer_compress(Buffer * input_buffer, Buffer * output_buffer) | |
82 | { | |
83 | char buf[4096]; | |
84 | int status; | |
85 | ||
86 | /* This case is not handled below. */ | |
87 | if (buffer_len(input_buffer) == 0) | |
88 | return; | |
89 | ||
90 | /* Input is the contents of the input buffer. */ | |
91 | outgoing_stream.next_in = (u_char *) buffer_ptr(input_buffer); | |
92 | outgoing_stream.avail_in = buffer_len(input_buffer); | |
93 | ||
94 | /* Loop compressing until deflate() returns with avail_out != 0. */ | |
95 | do { | |
96 | /* Set up fixed-size output buffer. */ | |
97 | outgoing_stream.next_out = (u_char *)buf; | |
98 | outgoing_stream.avail_out = sizeof(buf); | |
99 | ||
100 | /* Compress as much data into the buffer as possible. */ | |
101 | status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH); | |
102 | switch (status) { | |
103 | case Z_OK: | |
104 | /* Append compressed data to output_buffer. */ | |
105 | buffer_append(output_buffer, buf, | |
106 | sizeof(buf) - outgoing_stream.avail_out); | |
107 | break; | |
108 | default: | |
109 | fatal("buffer_compress: deflate returned %d", status); | |
110 | /* NOTREACHED */ | |
111 | } | |
112 | } while (outgoing_stream.avail_out == 0); | |
113 | } | |
114 | ||
115 | /* | |
116 | * Uncompresses the contents of input_buffer into output_buffer. All packets | |
117 | * uncompressed using this function will form a single compressed data | |
118 | * stream; however, data will be flushed at the end of every call so that | |
119 | * each output_buffer. This must be called for the same size units that the | |
120 | * buffer_compress was called, and in the same order that buffers compressed | |
121 | * with that. This appends the uncompressed data to the output buffer. | |
122 | */ | |
123 | ||
124 | void | |
125 | buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer) | |
126 | { | |
127 | char buf[4096]; | |
128 | int status; | |
129 | ||
130 | incoming_stream.next_in = (u_char *) buffer_ptr(input_buffer); | |
131 | incoming_stream.avail_in = buffer_len(input_buffer); | |
132 | ||
133 | for (;;) { | |
134 | /* Set up fixed-size output buffer. */ | |
135 | incoming_stream.next_out = (u_char *) buf; | |
136 | incoming_stream.avail_out = sizeof(buf); | |
137 | ||
138 | status = inflate(&incoming_stream, Z_PARTIAL_FLUSH); | |
139 | switch (status) { | |
140 | case Z_OK: | |
141 | buffer_append(output_buffer, buf, | |
142 | sizeof(buf) - incoming_stream.avail_out); | |
143 | break; | |
144 | case Z_BUF_ERROR: | |
145 | /* | |
146 | * Comments in zlib.h say that we should keep calling | |
147 | * inflate() until we get an error. This appears to | |
148 | * be the error that we get. | |
149 | */ | |
150 | return; | |
151 | default: | |
152 | fatal("buffer_uncompress: inflate returned %d", status); | |
153 | /* NOTREACHED */ | |
154 | } | |
155 | } | |
156 | } |