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 1.13 2001/02/08 19:30:51 itojun Exp $");
22 static z_stream incoming_stream;
23 static z_stream outgoing_stream;
26 * Initializes compression; level is compression level from 1 to 9
31 buffer_compress_init(int level)
33 debug("Enabling compression at level %d.", level);
34 if (level < 1 || level > 9)
35 fatal("Bad compression level %d.", level);
36 inflateInit(&incoming_stream);
37 deflateInit(&outgoing_stream, level);
40 /* Frees any data structures allocated for compression. */
43 buffer_compress_uninit(void)
45 debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
46 outgoing_stream.total_in, outgoing_stream.total_out,
47 outgoing_stream.total_in == 0 ? 0.0 :
48 (double) outgoing_stream.total_out / outgoing_stream.total_in);
49 debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
50 incoming_stream.total_out, incoming_stream.total_in,
51 incoming_stream.total_out == 0 ? 0.0 :
52 (double) incoming_stream.total_in / incoming_stream.total_out);
53 inflateEnd(&incoming_stream);
54 deflateEnd(&outgoing_stream);
58 * Compresses the contents of input_buffer into output_buffer. All packets
59 * compressed using this function will form a single compressed data stream;
60 * however, data will be flushed at the end of every call so that each
61 * output_buffer can be decompressed independently (but in the appropriate
62 * order since they together form a single compression stream) by the
63 * receiver. This appends the compressed data to the output buffer.
67 buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
72 /* This case is not handled below. */
73 if (buffer_len(input_buffer) == 0)
76 /* Input is the contents of the input buffer. */
77 outgoing_stream.next_in = (u_char *) buffer_ptr(input_buffer);
78 outgoing_stream.avail_in = buffer_len(input_buffer);
80 /* Loop compressing until deflate() returns with avail_out != 0. */
82 /* Set up fixed-size output buffer. */
83 outgoing_stream.next_out = (u_char *)buf;
84 outgoing_stream.avail_out = sizeof(buf);
86 /* Compress as much data into the buffer as possible. */
87 status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
90 /* Append compressed data to output_buffer. */
91 buffer_append(output_buffer, buf,
92 sizeof(buf) - outgoing_stream.avail_out);
95 fatal("buffer_compress: deflate returned %d", status);
98 } while (outgoing_stream.avail_out == 0);
102 * Uncompresses the contents of input_buffer into output_buffer. All packets
103 * uncompressed using this function will form a single compressed data
104 * stream; however, data will be flushed at the end of every call so that
105 * each output_buffer. This must be called for the same size units that the
106 * buffer_compress was called, and in the same order that buffers compressed
107 * with that. This appends the uncompressed data to the output buffer.
111 buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
116 incoming_stream.next_in = (u_char *) buffer_ptr(input_buffer);
117 incoming_stream.avail_in = buffer_len(input_buffer);
120 /* Set up fixed-size output buffer. */
121 incoming_stream.next_out = (u_char *) buf;
122 incoming_stream.avail_out = sizeof(buf);
124 status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
127 buffer_append(output_buffer, buf,
128 sizeof(buf) - incoming_stream.avail_out);
132 * Comments in zlib.h say that we should keep calling
133 * inflate() until we get an error. This appears to
134 * be the error that we get.
138 fatal("buffer_uncompress: inflate returned %d", status);