Annotation of src/usr.bin/ssh/compress.c, Revision 1.10
1.1 deraadt 1: /*
1.3 deraadt 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.
1.7 markus 6: *
1.9 deraadt 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".
1.3 deraadt 12: */
1.1 deraadt 13:
14: #include "includes.h"
1.10 ! markus 15: RCSID("$OpenBSD: compress.c,v 1.9 2000/09/07 20:27:50 deraadt Exp $");
1.1 deraadt 16:
17: #include "ssh.h"
18: #include "buffer.h"
19: #include "zlib.h"
20:
21: static z_stream incoming_stream;
22: static z_stream outgoing_stream;
23:
1.4 markus 24: /*
25: * Initializes compression; level is compression level from 1 to 9
26: * (as in gzip).
27: */
1.1 deraadt 28:
1.7 markus 29: void
1.2 markus 30: buffer_compress_init(int level)
1.1 deraadt 31: {
1.2 markus 32: debug("Enabling compression at level %d.", level);
33: if (level < 1 || level > 9)
34: fatal("Bad compression level %d.", level);
35: inflateInit(&incoming_stream);
36: deflateInit(&outgoing_stream, level);
1.1 deraadt 37: }
38:
39: /* Frees any data structures allocated for compression. */
40:
1.7 markus 41: void
1.2 markus 42: buffer_compress_uninit()
1.1 deraadt 43: {
1.2 markus 44: debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
45: outgoing_stream.total_in, outgoing_stream.total_out,
46: outgoing_stream.total_in == 0 ? 0.0 :
47: (double) outgoing_stream.total_out / outgoing_stream.total_in);
48: debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
49: incoming_stream.total_out, incoming_stream.total_in,
50: incoming_stream.total_out == 0 ? 0.0 :
51: (double) incoming_stream.total_in / incoming_stream.total_out);
52: inflateEnd(&incoming_stream);
53: deflateEnd(&outgoing_stream);
1.1 deraadt 54: }
55:
1.4 markus 56: /*
57: * Compresses the contents of input_buffer into output_buffer. All packets
58: * compressed using this function will form a single compressed data stream;
59: * however, data will be flushed at the end of every call so that each
60: * output_buffer can be decompressed independently (but in the appropriate
61: * order since they together form a single compression stream) by the
62: * receiver. This appends the compressed data to the output buffer.
63: */
1.1 deraadt 64:
1.7 markus 65: void
1.2 markus 66: buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
1.1 deraadt 67: {
1.2 markus 68: char buf[4096];
69: int status;
1.1 deraadt 70:
1.2 markus 71: /* This case is not handled below. */
72: if (buffer_len(input_buffer) == 0)
73: return;
74:
75: /* Input is the contents of the input buffer. */
1.10 ! markus 76: outgoing_stream.next_in = (u_char *) buffer_ptr(input_buffer);
1.2 markus 77: outgoing_stream.avail_in = buffer_len(input_buffer);
78:
79: /* Loop compressing until deflate() returns with avail_out != 0. */
80: do {
81: /* Set up fixed-size output buffer. */
1.10 ! markus 82: outgoing_stream.next_out = (u_char *)buf;
1.2 markus 83: outgoing_stream.avail_out = sizeof(buf);
84:
85: /* Compress as much data into the buffer as possible. */
86: status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
87: switch (status) {
88: case Z_OK:
89: /* Append compressed data to output_buffer. */
90: buffer_append(output_buffer, buf,
1.6 markus 91: sizeof(buf) - outgoing_stream.avail_out);
1.2 markus 92: break;
93: default:
94: fatal("buffer_compress: deflate returned %d", status);
95: /* NOTREACHED */
96: }
1.6 markus 97: } while (outgoing_stream.avail_out == 0);
1.1 deraadt 98: }
99:
1.4 markus 100: /*
101: * Uncompresses the contents of input_buffer into output_buffer. All packets
102: * uncompressed using this function will form a single compressed data
103: * stream; however, data will be flushed at the end of every call so that
104: * each output_buffer. This must be called for the same size units that the
105: * buffer_compress was called, and in the same order that buffers compressed
106: * with that. This appends the uncompressed data to the output buffer.
107: */
1.1 deraadt 108:
1.7 markus 109: void
1.2 markus 110: buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
1.1 deraadt 111: {
1.2 markus 112: char buf[4096];
113: int status;
1.1 deraadt 114:
1.10 ! markus 115: incoming_stream.next_in = (u_char *) buffer_ptr(input_buffer);
1.2 markus 116: incoming_stream.avail_in = buffer_len(input_buffer);
1.1 deraadt 117:
1.6 markus 118: for (;;) {
119: /* Set up fixed-size output buffer. */
1.10 ! markus 120: incoming_stream.next_out = (u_char *) buf;
1.6 markus 121: incoming_stream.avail_out = sizeof(buf);
1.1 deraadt 122:
1.2 markus 123: status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
124: switch (status) {
125: case Z_OK:
126: buffer_append(output_buffer, buf,
1.6 markus 127: sizeof(buf) - incoming_stream.avail_out);
1.2 markus 128: break;
129: case Z_BUF_ERROR:
1.4 markus 130: /*
131: * Comments in zlib.h say that we should keep calling
132: * inflate() until we get an error. This appears to
133: * be the error that we get.
134: */
1.2 markus 135: return;
136: default:
137: fatal("buffer_uncompress: inflate returned %d", status);
1.6 markus 138: /* NOTREACHED */
1.2 markus 139: }
1.1 deraadt 140: }
141: }
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