1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Interface to packet compression for ssh.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*/
#include "includes.h"
RCSID("$OpenBSD: compress.c,v 1.9 2000/09/07 20:27:50 deraadt Exp $");
#include "ssh.h"
#include "buffer.h"
#include "zlib.h"
static z_stream incoming_stream;
static z_stream outgoing_stream;
/*
* Initializes compression; level is compression level from 1 to 9
* (as in gzip).
*/
void
buffer_compress_init(int level)
{
debug("Enabling compression at level %d.", level);
if (level < 1 || level > 9)
fatal("Bad compression level %d.", level);
inflateInit(&incoming_stream);
deflateInit(&outgoing_stream, level);
}
/* Frees any data structures allocated for compression. */
void
buffer_compress_uninit()
{
debug("compress outgoing: raw data %lu, compressed %lu, factor %.2f",
outgoing_stream.total_in, outgoing_stream.total_out,
outgoing_stream.total_in == 0 ? 0.0 :
(double) outgoing_stream.total_out / outgoing_stream.total_in);
debug("compress incoming: raw data %lu, compressed %lu, factor %.2f",
incoming_stream.total_out, incoming_stream.total_in,
incoming_stream.total_out == 0 ? 0.0 :
(double) incoming_stream.total_in / incoming_stream.total_out);
inflateEnd(&incoming_stream);
deflateEnd(&outgoing_stream);
}
/*
* Compresses the contents of input_buffer into output_buffer. All packets
* compressed using this function will form a single compressed data stream;
* however, data will be flushed at the end of every call so that each
* output_buffer can be decompressed independently (but in the appropriate
* order since they together form a single compression stream) by the
* receiver. This appends the compressed data to the output buffer.
*/
void
buffer_compress(Buffer * input_buffer, Buffer * output_buffer)
{
char buf[4096];
int status;
/* This case is not handled below. */
if (buffer_len(input_buffer) == 0)
return;
/* Input is the contents of the input buffer. */
outgoing_stream.next_in = (unsigned char *) buffer_ptr(input_buffer);
outgoing_stream.avail_in = buffer_len(input_buffer);
/* Loop compressing until deflate() returns with avail_out != 0. */
do {
/* Set up fixed-size output buffer. */
outgoing_stream.next_out = (unsigned char *)buf;
outgoing_stream.avail_out = sizeof(buf);
/* Compress as much data into the buffer as possible. */
status = deflate(&outgoing_stream, Z_PARTIAL_FLUSH);
switch (status) {
case Z_OK:
/* Append compressed data to output_buffer. */
buffer_append(output_buffer, buf,
sizeof(buf) - outgoing_stream.avail_out);
break;
default:
fatal("buffer_compress: deflate returned %d", status);
/* NOTREACHED */
}
} while (outgoing_stream.avail_out == 0);
}
/*
* Uncompresses the contents of input_buffer into output_buffer. All packets
* uncompressed using this function will form a single compressed data
* stream; however, data will be flushed at the end of every call so that
* each output_buffer. This must be called for the same size units that the
* buffer_compress was called, and in the same order that buffers compressed
* with that. This appends the uncompressed data to the output buffer.
*/
void
buffer_uncompress(Buffer * input_buffer, Buffer * output_buffer)
{
char buf[4096];
int status;
incoming_stream.next_in = (unsigned char *) buffer_ptr(input_buffer);
incoming_stream.avail_in = buffer_len(input_buffer);
for (;;) {
/* Set up fixed-size output buffer. */
incoming_stream.next_out = (unsigned char *) buf;
incoming_stream.avail_out = sizeof(buf);
status = inflate(&incoming_stream, Z_PARTIAL_FLUSH);
switch (status) {
case Z_OK:
buffer_append(output_buffer, buf,
sizeof(buf) - incoming_stream.avail_out);
break;
case Z_BUF_ERROR:
/*
* Comments in zlib.h say that we should keep calling
* inflate() until we get an error. This appears to
* be the error that we get.
*/
return;
default:
fatal("buffer_uncompress: inflate returned %d", status);
/* NOTREACHED */
}
}
}
|
