1 /*
2 * OpenVPN -- An application to securely tunnel IP networks
3 * over a single UDP port, with support for SSL/TLS-based
4 * session authentication and key exchange,
5 * packet encryption, packet authentication, and
6 * packet compression.
7 *
8 * Copyright (C) 2002-2022 OpenVPN Inc <sales@openvpn.net>
9 * Copyright (C) 2013-2022 Gert Doering <gert@greenie.muc.de>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2
13 * as published by the Free Software Foundation.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write to the Free Software Foundation, Inc.,
22 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
23 */
24
25 #ifdef HAVE_CONFIG_H
26 #include "config.h"
27 #elif defined(_MSC_VER)
28 #include "config-msvc.h"
29 #endif
30
31 #include "syshead.h"
32
33 #if defined(ENABLE_LZ4)
34
35 #if defined(NEED_COMPAT_LZ4)
36 #include "compat-lz4.h"
37 #else
38 #include <lz4.h>
39 #endif
40
41 #include "comp.h"
42 #include "error.h"
43
44 #include "memdbg.h"
45
46
47 static void
lz4_compress_init(struct compress_context * compctx)48 lz4_compress_init(struct compress_context *compctx)
49 {
50 msg(D_INIT_MEDIUM, "LZ4 compression initializing");
51 ASSERT(compctx->flags & COMP_F_SWAP);
52 }
53
54 static void
lz4v2_compress_init(struct compress_context * compctx)55 lz4v2_compress_init(struct compress_context *compctx)
56 {
57 msg(D_INIT_MEDIUM, "LZ4v2 compression initializing");
58 }
59
60 static void
lz4_compress_uninit(struct compress_context * compctx)61 lz4_compress_uninit(struct compress_context *compctx)
62 {
63 }
64
65 static bool
do_lz4_compress(struct buffer * buf,struct buffer * work,struct compress_context * compctx,const struct frame * frame)66 do_lz4_compress(struct buffer *buf,
67 struct buffer *work,
68 struct compress_context *compctx,
69 const struct frame *frame)
70 {
71 /*
72 * In order to attempt compression, length must be at least COMPRESS_THRESHOLD.
73 * and asymmetric compression must be disabled
74 */
75 if (buf->len >= COMPRESS_THRESHOLD && (compctx->flags & COMP_F_ALLOW_COMPRESS))
76 {
77 const size_t ps = PAYLOAD_SIZE(frame);
78 int zlen_max = ps + COMP_EXTRA_BUFFER(ps);
79 int zlen;
80
81 ASSERT(buf_init(work, FRAME_HEADROOM(frame)));
82 ASSERT(buf_safe(work, zlen_max));
83
84 if (buf->len > ps)
85 {
86 dmsg(D_COMP_ERRORS, "LZ4 compression buffer overflow");
87 buf->len = 0;
88 return false;
89 }
90
91 zlen = LZ4_compress_default((const char *)BPTR(buf), (char *)BPTR(work), BLEN(buf), zlen_max);
92
93 if (zlen <= 0)
94 {
95 dmsg(D_COMP_ERRORS, "LZ4 compression error");
96 buf->len = 0;
97 return false;
98 }
99
100 ASSERT(buf_safe(work, zlen));
101 work->len = zlen;
102
103
104 dmsg(D_COMP, "LZ4 compress %d -> %d", buf->len, work->len);
105 compctx->pre_compress += buf->len;
106 compctx->post_compress += work->len;
107 return true;
108 }
109 return false;
110 }
111
112
113 static void
lz4_compress(struct buffer * buf,struct buffer work,struct compress_context * compctx,const struct frame * frame)114 lz4_compress(struct buffer *buf, struct buffer work,
115 struct compress_context *compctx,
116 const struct frame *frame)
117 {
118 bool compressed;
119 if (buf->len <= 0)
120 {
121 return;
122 }
123
124 compressed = do_lz4_compress(buf, &work, compctx, frame);
125
126 /* On error do_lz4_compress sets buf len to zero, just return */
127 if (buf->len == 0)
128 {
129 return;
130 }
131
132 /* did compression save us anything? */
133 {
134 uint8_t comp_head_byte = NO_COMPRESS_BYTE_SWAP;
135 if (compressed && work.len < buf->len)
136 {
137 *buf = work;
138 comp_head_byte = LZ4_COMPRESS_BYTE;
139 }
140
141 {
142 uint8_t *head = BPTR(buf);
143 uint8_t *tail = BEND(buf);
144 ASSERT(buf_safe(buf, 1));
145 ++buf->len;
146
147 /* move head byte of payload to tail */
148 *tail = *head;
149 *head = comp_head_byte;
150 }
151 }
152 }
153
154
155 static void
lz4v2_compress(struct buffer * buf,struct buffer work,struct compress_context * compctx,const struct frame * frame)156 lz4v2_compress(struct buffer *buf, struct buffer work,
157 struct compress_context *compctx,
158 const struct frame *frame)
159 {
160 bool compressed;
161 if (buf->len <= 0)
162 {
163 return;
164 }
165
166 compressed = do_lz4_compress(buf, &work, compctx, frame);
167
168 /* On Error just return */
169 if (buf->len == 0)
170 {
171 return;
172 }
173
174 /* did compression save us anything? Include 2 byte compression header
175 * in calculation */
176 if (compressed && work.len + 2 < buf->len)
177 {
178 ASSERT(buf_prepend(&work, 2));
179 uint8_t *head = BPTR(&work);
180 head[0] = COMP_ALGV2_INDICATOR_BYTE;
181 head[1] = COMP_ALGV2_LZ4_BYTE;
182 *buf = work;
183 }
184 else
185 {
186 compv2_escape_data_ifneeded(buf);
187 }
188 }
189
190 static void
do_lz4_decompress(size_t zlen_max,struct buffer * work,struct buffer * buf,struct compress_context * compctx)191 do_lz4_decompress(size_t zlen_max,
192 struct buffer *work,
193 struct buffer *buf,
194 struct compress_context *compctx)
195 {
196 int uncomp_len;
197 ASSERT(buf_safe(work, zlen_max));
198 uncomp_len = LZ4_decompress_safe((const char *)BPTR(buf), (char *)BPTR(work), (size_t)BLEN(buf), zlen_max);
199 if (uncomp_len <= 0)
200 {
201 dmsg(D_COMP_ERRORS, "LZ4 decompression error: %d", uncomp_len);
202 buf->len = 0;
203 return;
204 }
205
206 ASSERT(buf_safe(work, uncomp_len));
207 work->len = uncomp_len;
208
209 dmsg(D_COMP, "LZ4 decompress %d -> %d", buf->len, work->len);
210 compctx->pre_decompress += buf->len;
211 compctx->post_decompress += work->len;
212
213 *buf = *work;
214 }
215
216 static void
lz4_decompress(struct buffer * buf,struct buffer work,struct compress_context * compctx,const struct frame * frame)217 lz4_decompress(struct buffer *buf, struct buffer work,
218 struct compress_context *compctx,
219 const struct frame *frame)
220 {
221 size_t zlen_max = EXPANDED_SIZE(frame);
222 uint8_t c; /* flag indicating whether or not our peer compressed */
223
224 if (buf->len <= 0)
225 {
226 return;
227 }
228
229 ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
230
231 /* do unframing/swap (assumes buf->len > 0) */
232 {
233 uint8_t *head = BPTR(buf);
234 c = *head;
235 --buf->len;
236 *head = *BEND(buf);
237 }
238
239 if (c == LZ4_COMPRESS_BYTE) /* packet was compressed */
240 {
241 do_lz4_decompress(zlen_max, &work, buf, compctx);
242 }
243 else if (c == NO_COMPRESS_BYTE_SWAP) /* packet was not compressed */
244 {
245 }
246 else
247 {
248 dmsg(D_COMP_ERRORS, "Bad LZ4 decompression header byte: %d", c);
249 buf->len = 0;
250 }
251 }
252
253 static void
lz4v2_decompress(struct buffer * buf,struct buffer work,struct compress_context * compctx,const struct frame * frame)254 lz4v2_decompress(struct buffer *buf, struct buffer work,
255 struct compress_context *compctx,
256 const struct frame *frame)
257 {
258 size_t zlen_max = EXPANDED_SIZE(frame);
259 uint8_t c; /* flag indicating whether or not our peer compressed */
260
261 if (buf->len <= 0)
262 {
263 return;
264 }
265
266 ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
267
268 /* do unframing/swap (assumes buf->len > 0) */
269 uint8_t *head = BPTR(buf);
270 c = *head;
271
272 /* Not compressed */
273 if (c != COMP_ALGV2_INDICATOR_BYTE)
274 {
275 return;
276 }
277
278 /* Packet to short to make sense */
279 if (buf->len <= 1)
280 {
281 buf->len = 0;
282 return;
283 }
284
285 c = head[1];
286 if (c == COMP_ALGV2_LZ4_BYTE) /* packet was compressed */
287 {
288 buf_advance(buf,2);
289 do_lz4_decompress(zlen_max, &work, buf, compctx);
290 }
291 else if (c == COMP_ALGV2_UNCOMPRESSED_BYTE)
292 {
293 buf_advance(buf,2);
294 }
295 else
296 {
297 dmsg(D_COMP_ERRORS, "Bad LZ4v2 decompression header byte: %d", c);
298 buf->len = 0;
299 }
300 }
301
302 const struct compress_alg lz4_alg = {
303 "lz4",
304 lz4_compress_init,
305 lz4_compress_uninit,
306 lz4_compress,
307 lz4_decompress
308 };
309
310 const struct compress_alg lz4v2_alg = {
311 "lz4v2",
312 lz4v2_compress_init,
313 lz4_compress_uninit,
314 lz4v2_compress,
315 lz4v2_decompress
316 };
317
318 #else /* if defined(ENABLE_LZ4) */
319 static void
dummy(void)320 dummy(void)
321 {
322 }
323 #endif /* ENABLE_LZ4 */
324