2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Interface to packet compression for ssh.
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".
15 RCSID("$OpenBSD: compress.c,v 1.19 2002/03/18 17:31:54 provos Exp $");
22 z_stream incoming_stream;
23 z_stream outgoing_stream;
24 static int compress_init_send_called = 0;
25 static int compress_init_recv_called = 0;
26 static int inflate_failed = 0;
27 static int deflate_failed = 0;
30 * Initializes compression; level is compression level from 1 to 9
35 buffer_compress_init_send(int level)
37 if (compress_init_send_called == 1)
38 deflateEnd(&outgoing_stream);
39 compress_init_send_called = 1;
40 debug("Enabling compression at level %d.", level);
41 if (level < 1 || level > 9)
42 fatal("Bad compression level %d.", level);
43 deflateInit(&outgoing_stream, level);
46 buffer_compress_init_recv(void)
48 if (compress_init_recv_called == 1)
49 inflateEnd(&incoming_stream);
50 compress_init_recv_called = 1;
51 inflateInit(&incoming_stream);
54 /* Frees any data structures allocated for compression. */
57 buffer_compress_uninit(void)
59 debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
60 outgoing_stream.total_in, outgoing_stream.total_out,
61 outgoing_stream.total_in == 0 ? 0.0 :
62 (double) outgoing_stream.total_out / outgoing_stream.total_in);
63 debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
64 incoming_stream.total_out, incoming_stream.total_in,
65 incoming_stream.total_out == 0 ? 0.0 :
66 (double) incoming_stream.total_in / incoming_stream.total_out);
67 if (compress_init_recv_called == 1 && inflate_failed == 0)
68 inflateEnd(&incoming_stream);
69 if (compress_init_send_called == 1 && deflate_failed == 0)
70 deflateEnd(&outgoing_stream);
74 * Compresses the contents of input_buffer into output_buffer. All packets
75 * compressed using this function will form a single compressed data stream;
76 * however, data will be flushed at the end of every call so that each
77 * output_buffer can be decompressed independently (but in the appropriate
78 * order since they together form a single compression stream) by the
79 * receiver. This appends the compressed data to the output buffer.
83 buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
88 /* This case is not handled below. */
89 if (buffer_len(input_buffer) == 0)
92 /* Input is the contents of the input buffer. */
93 outgoing_stream.next_in = buffer_ptr(input_buffer);
94 outgoing_stream.avail_in = buffer_len(input_buffer);
96 /* Loop compressing until deflate() returns with avail_out != 0. */
98 /* Set up fixed-size output buffer. */
99 outgoing_stream.next_out = buf;
100 outgoing_stream.avail_out = sizeof(buf);
102 /* Compress as much data into the buffer as possible. */
103 status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
106 /* Append compressed data to output_buffer. */
107 buffer_append(output_buffer, buf,
108 sizeof(buf) - outgoing_stream.avail_out);
112 fatal("buffer_compress: deflate returned %d", status);
115 } while (outgoing_stream.avail_out == 0);
119 * Uncompresses the contents of input_buffer into output_buffer. All packets
120 * uncompressed using this function will form a single compressed data
121 * stream; however, data will be flushed at the end of every call so that
122 * each output_buffer. This must be called for the same size units that the
123 * buffer_compress was called, and in the same order that buffers compressed
124 * with that. This appends the uncompressed data to the output buffer.
128 buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
133 incoming_stream.next_in = buffer_ptr(input_buffer);
134 incoming_stream.avail_in = buffer_len(input_buffer);
137 /* Set up fixed-size output buffer. */
138 incoming_stream.next_out = buf;
139 incoming_stream.avail_out = sizeof(buf);
141 status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
144 buffer_append(output_buffer, buf,
145 sizeof(buf) - incoming_stream.avail_out);
149 * Comments in zlib.h say that we should keep calling
150 * inflate() until we get an error. This appears to
151 * be the error that we get.
156 fatal("buffer_uncompress: inflate returned %d", status);