aboutsummaryrefslogtreecommitdiff
path: root/libssh/gzip.c
blob: c9b0545cc3e533791bc6d1858df96c329f007c6e (plain)
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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
/*
 * gzip.c - hooks for compression of packets
 *
 * This file is part of the SSH Library
 *
 * Copyright (c) 2003      by Aris Adamantiadis
 * Copyright (c) 2009      by Andreas Schneider <mail@cynapses.org>
 *
 * The SSH Library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The SSH Library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the SSH Library; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#include "config.h"
#include "libssh/priv.h"
#include "libssh/buffer.h"
#include "libssh/session.h"

#if defined(HAVE_LIBZ) && defined(WITH_LIBZ)

#include <zlib.h>
#include <string.h>
#include <stdlib.h>

#define BLOCKSIZE 4092

static z_stream *initcompress(ssh_session session, int level) {
  z_stream *stream = NULL;
  int status;

  stream = malloc(sizeof(z_stream));
  if (stream == NULL) {
    return NULL;
  }
  memset(stream, 0, sizeof(z_stream));

  status = deflateInit(stream, level);
  if (status != Z_OK) {
    SAFE_FREE(stream);
    ssh_set_error(session, SSH_FATAL,
        "status %d inititalising zlib deflate", status);
    return NULL;
  }

  return stream;
}

static ssh_buffer gzip_compress(ssh_session session,ssh_buffer source,int level){
  z_stream *zout = session->current_crypto->compress_out_ctx;
  void *in_ptr = buffer_get(source);
  unsigned long in_size = buffer_get_len(source);
  ssh_buffer dest = NULL;
  static unsigned char out_buf[BLOCKSIZE] = {0};
  unsigned long len;
  int status;

  if(zout == NULL) {
    zout = session->current_crypto->compress_out_ctx = initcompress(session, level);
    if (zout == NULL) {
      return NULL;
    }
  }

  dest = buffer_new();
  if (dest == NULL) {
    return NULL;
  }

  zout->next_out = out_buf;
  zout->next_in = in_ptr;
  zout->avail_in = in_size;
  do {
    zout->avail_out = BLOCKSIZE;
    status = deflate(zout, Z_PARTIAL_FLUSH);
    if (status != Z_OK) {
      buffer_free(dest);
      ssh_set_error(session, SSH_FATAL,
          "status %d deflating zlib packet", status);
      return NULL;
    }
    len = BLOCKSIZE - zout->avail_out;
    if (buffer_add_data(dest, out_buf, len) < 0) {
      buffer_free(dest);
      return NULL;
    }
    zout->next_out = out_buf;
  } while (zout->avail_out == 0);

  return dest;
}

int compress_buffer(ssh_session session, ssh_buffer buf) {
  ssh_buffer dest = NULL;

  dest = gzip_compress(session, buf, 9);
  if (dest == NULL) {
    return -1;
  }

  if (buffer_reinit(buf) < 0) {
    buffer_free(dest);
    return -1;
  }

  if (buffer_add_data(buf, buffer_get(dest), buffer_get_len(dest)) < 0) {
    buffer_free(dest);
    return -1;
  }

  buffer_free(dest);
  return 0;
}

/* decompression */

static z_stream *initdecompress(ssh_session session) {
  z_stream *stream = NULL;
  int status;

  stream = malloc(sizeof(z_stream));
  if (stream == NULL) {
    return NULL;
  }
  memset(stream,0,sizeof(z_stream));

  status = inflateInit(stream);
  if (status != Z_OK) {
    SAFE_FREE(stream);
    ssh_set_error(session, SSH_FATAL,
        "Status = %d initiating inflate context!", status);
    return NULL;
  }

  return stream;
}

static ssh_buffer gzip_decompress(ssh_session session, ssh_buffer source, size_t maxlen) {
  z_stream *zin = session->current_crypto->compress_in_ctx;
  void *in_ptr = buffer_get_rest(source);
  unsigned long in_size = buffer_get_rest_len(source);
  static unsigned char out_buf[BLOCKSIZE] = {0};
  ssh_buffer dest = NULL;
  unsigned long len;
  int status;

  if (zin == NULL) {
    zin = session->current_crypto->compress_in_ctx = initdecompress(session);
    if (zin == NULL) {
      return NULL;
    }
  }

  dest = buffer_new();
  if (dest == NULL) {
    return NULL;
  }

  zin->next_out = out_buf;
  zin->next_in = in_ptr;
  zin->avail_in = in_size;

  do {
    zin->avail_out = BLOCKSIZE;
    status = inflate(zin, Z_PARTIAL_FLUSH);
    if (status != Z_OK) {
      ssh_set_error(session, SSH_FATAL,
          "status %d inflating zlib packet", status);
      buffer_free(dest);
      return NULL;
    }

    len = BLOCKSIZE - zin->avail_out;
    if (buffer_add_data(dest,out_buf,len) < 0) {
      buffer_free(dest);
      return NULL;
    }
    if (buffer_get_len(dest) > maxlen){
      /* Size of packet exceded, avoid a denial of service attack */
      buffer_free(dest);
      return NULL;
    }
    zin->next_out = out_buf;
  } while (zin->avail_out == 0);

  return dest;
}

int decompress_buffer(ssh_session session,ssh_buffer buf, size_t maxlen){
  ssh_buffer dest = NULL;

  dest = gzip_decompress(session,buf, maxlen);
  if (dest == NULL) {
    return -1;
  }

  if (buffer_reinit(buf) < 0) {
    buffer_free(dest);
    return -1;
  }

  if (buffer_add_data(buf, buffer_get(dest), buffer_get_len(dest)) < 0) {
    buffer_free(dest);
    return -1;
  }

  buffer_free(dest);
  return 0;
}

#endif /* HAVE_LIBZ && WITH_LIBZ */
/* vim: set ts=2 sw=2 et cindent: */