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1 | /* | |
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 | * Auxiliary functions for storing and retrieving various data types to/from | |
6 | * Buffers. | |
7 | * | |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
13 | * | |
14 | * | |
15 | * SSH2 packet format added by Markus Friedl | |
16 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
17 | * | |
18 | * Redistribution and use in source and binary forms, with or without | |
19 | * modification, are permitted provided that the following conditions | |
20 | * are met: | |
21 | * 1. Redistributions of source code must retain the above copyright | |
22 | * notice, this list of conditions and the following disclaimer. | |
23 | * 2. Redistributions in binary form must reproduce the above copyright | |
24 | * notice, this list of conditions and the following disclaimer in the | |
25 | * documentation and/or other materials provided with the distribution. | |
26 | * | |
27 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
28 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
29 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
30 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
31 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
32 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
33 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
34 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
35 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
36 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
37 | */ | |
38 | ||
39 | #include "includes.h" | |
40 | ||
41 | #include <openssl/bn.h> | |
42 | #include "bufaux.h" | |
43 | #include "xmalloc.h" | |
44 | #include "getput.h" | |
45 | #include "log.h" | |
46 | ||
47 | /* | |
48 | * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed | |
49 | * by (bits+7)/8 bytes of binary data, msb first. | |
50 | */ | |
51 | int | |
52 | buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value) | |
53 | { | |
54 | int bits = BN_num_bits(value); | |
55 | int bin_size = (bits + 7) / 8; | |
56 | u_char *buf = xmalloc(bin_size); | |
57 | int oi; | |
58 | char msg[2]; | |
59 | ||
60 | /* Get the value of in binary */ | |
61 | oi = BN_bn2bin(value, buf); | |
62 | if (oi != bin_size) { | |
63 | error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d", | |
64 | oi, bin_size); | |
65 | xfree(buf); | |
66 | return (-1); | |
67 | } | |
68 | ||
69 | /* Store the number of bits in the buffer in two bytes, msb first. */ | |
70 | PUT_16BIT(msg, bits); | |
71 | buffer_append(buffer, msg, 2); | |
72 | /* Store the binary data. */ | |
73 | buffer_append(buffer, (char *)buf, oi); | |
74 | ||
75 | memset(buf, 0, bin_size); | |
76 | xfree(buf); | |
77 | ||
78 | return (0); | |
79 | } | |
80 | ||
81 | void | |
82 | buffer_put_bignum(Buffer *buffer, const BIGNUM *value) | |
83 | { | |
84 | if (buffer_put_bignum_ret(buffer, value) == -1) | |
85 | fatal("buffer_put_bignum: buffer error"); | |
86 | } | |
87 | ||
88 | /* | |
89 | * Retrieves an BIGNUM from the buffer. | |
90 | */ | |
91 | int | |
92 | buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value) | |
93 | { | |
94 | u_int bits, bytes; | |
95 | u_char buf[2], *bin; | |
96 | ||
97 | /* Get the number for bits. */ | |
98 | if (buffer_get_ret(buffer, (char *) buf, 2) == -1) { | |
99 | error("buffer_get_bignum_ret: invalid length"); | |
100 | return (-1); | |
101 | } | |
102 | bits = GET_16BIT(buf); | |
103 | /* Compute the number of binary bytes that follow. */ | |
104 | bytes = (bits + 7) / 8; | |
105 | if (bytes > 8 * 1024) { | |
106 | error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes); | |
107 | return (-1); | |
108 | } | |
109 | if (buffer_len(buffer) < bytes) { | |
110 | error("buffer_get_bignum_ret: input buffer too small"); | |
111 | return (-1); | |
112 | } | |
113 | bin = buffer_ptr(buffer); | |
114 | BN_bin2bn(bin, bytes, value); | |
115 | if (buffer_consume_ret(buffer, bytes) == -1) { | |
116 | error("buffer_get_bignum_ret: buffer_consume failed"); | |
117 | return (-1); | |
118 | } | |
119 | return (0); | |
120 | } | |
121 | ||
122 | void | |
123 | buffer_get_bignum(Buffer *buffer, BIGNUM *value) | |
124 | { | |
125 | if (buffer_get_bignum_ret(buffer, value) == -1) | |
126 | fatal("buffer_get_bignum: buffer error"); | |
127 | } | |
128 | ||
129 | /* | |
130 | * Stores an BIGNUM in the buffer in SSH2 format. | |
131 | */ | |
132 | int | |
133 | buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value) | |
134 | { | |
135 | u_int bytes; | |
136 | u_char *buf; | |
137 | int oi; | |
138 | u_int hasnohigh = 0; | |
139 | ||
140 | if (BN_is_zero(value)) { | |
141 | buffer_put_int(buffer, 0); | |
142 | return 0; | |
143 | } | |
144 | if (value->neg) { | |
145 | error("buffer_put_bignum2_ret: negative numbers not supported"); | |
146 | return (-1); | |
147 | } | |
148 | bytes = BN_num_bytes(value) + 1; /* extra padding byte */ | |
149 | if (bytes < 2) { | |
150 | error("buffer_put_bignum2_ret: BN too small"); | |
151 | return (-1); | |
152 | } | |
153 | buf = xmalloc(bytes); | |
154 | buf[0] = 0x00; | |
155 | /* Get the value of in binary */ | |
156 | oi = BN_bn2bin(value, buf+1); | |
157 | if (oi < 0 || (u_int)oi != bytes - 1) { | |
158 | error("buffer_put_bignum2_ret: BN_bn2bin() failed: " | |
159 | "oi %d != bin_size %d", oi, bytes); | |
160 | xfree(buf); | |
161 | return (-1); | |
162 | } | |
163 | hasnohigh = (buf[1] & 0x80) ? 0 : 1; | |
164 | buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); | |
165 | memset(buf, 0, bytes); | |
166 | xfree(buf); | |
167 | return (0); | |
168 | } | |
169 | ||
170 | void | |
171 | buffer_put_bignum2(Buffer *buffer, const BIGNUM *value) | |
172 | { | |
173 | if (buffer_put_bignum2_ret(buffer, value) == -1) | |
174 | fatal("buffer_put_bignum2: buffer error"); | |
175 | } | |
176 | ||
177 | int | |
178 | buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value) | |
179 | { | |
180 | u_int len; | |
181 | u_char *bin; | |
182 | ||
183 | if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) { | |
184 | error("buffer_get_bignum2_ret: invalid bignum"); | |
185 | return (-1); | |
186 | } | |
187 | ||
188 | if (len > 0 && (bin[0] & 0x80)) { | |
189 | error("buffer_get_bignum2_ret: negative numbers not supported"); | |
190 | xfree(bin); | |
191 | return (-1); | |
192 | } | |
193 | if (len > 8 * 1024) { | |
194 | error("buffer_get_bignum2_ret: cannot handle BN of size %d", len); | |
195 | xfree(bin); | |
196 | return (-1); | |
197 | } | |
198 | BN_bin2bn(bin, len, value); | |
199 | xfree(bin); | |
200 | return (0); | |
201 | } | |
202 | ||
203 | void | |
204 | buffer_get_bignum2(Buffer *buffer, BIGNUM *value) | |
205 | { | |
206 | if (buffer_get_bignum2_ret(buffer, value) == -1) | |
207 | fatal("buffer_get_bignum2: buffer error"); | |
208 | } | |
209 | ||
210 | /* | |
211 | * Returns integers from the buffer (msb first). | |
212 | */ | |
213 | ||
214 | int | |
215 | buffer_get_short_ret(u_short *ret, Buffer *buffer) | |
216 | { | |
217 | u_char buf[2]; | |
218 | ||
219 | if (buffer_get_ret(buffer, (char *) buf, 2) == -1) | |
220 | return (-1); | |
221 | *ret = GET_16BIT(buf); | |
222 | return (0); | |
223 | } | |
224 | ||
225 | u_short | |
226 | buffer_get_short(Buffer *buffer) | |
227 | { | |
228 | u_short ret; | |
229 | ||
230 | if (buffer_get_short_ret(&ret, buffer) == -1) | |
231 | fatal("buffer_get_short: buffer error"); | |
232 | ||
233 | return (ret); | |
234 | } | |
235 | ||
236 | int | |
237 | buffer_get_int_ret(u_int *ret, Buffer *buffer) | |
238 | { | |
239 | u_char buf[4]; | |
240 | ||
241 | if (buffer_get_ret(buffer, (char *) buf, 4) == -1) | |
242 | return (-1); | |
243 | *ret = GET_32BIT(buf); | |
244 | return (0); | |
245 | } | |
246 | ||
247 | u_int | |
248 | buffer_get_int(Buffer *buffer) | |
249 | { | |
250 | u_int ret; | |
251 | ||
252 | if (buffer_get_int_ret(&ret, buffer) == -1) | |
253 | fatal("buffer_get_int: buffer error"); | |
254 | ||
255 | return (ret); | |
256 | } | |
257 | ||
258 | int | |
259 | buffer_get_int64_ret(u_int64_t *ret, Buffer *buffer) | |
260 | { | |
261 | u_char buf[8]; | |
262 | ||
263 | if (buffer_get_ret(buffer, (char *) buf, 8) == -1) | |
264 | return (-1); | |
265 | *ret = GET_64BIT(buf); | |
266 | return (0); | |
267 | } | |
268 | ||
269 | u_int64_t | |
270 | buffer_get_int64(Buffer *buffer) | |
271 | { | |
272 | u_int64_t ret; | |
273 | ||
274 | if (buffer_get_int64_ret(&ret, buffer) == -1) | |
275 | fatal("buffer_get_int: buffer error"); | |
276 | ||
277 | return (ret); | |
278 | } | |
279 | ||
280 | /* | |
281 | * Stores integers in the buffer, msb first. | |
282 | */ | |
283 | void | |
284 | buffer_put_short(Buffer *buffer, u_short value) | |
285 | { | |
286 | char buf[2]; | |
287 | ||
288 | PUT_16BIT(buf, value); | |
289 | buffer_append(buffer, buf, 2); | |
290 | } | |
291 | ||
292 | void | |
293 | buffer_put_int(Buffer *buffer, u_int value) | |
294 | { | |
295 | char buf[4]; | |
296 | ||
297 | PUT_32BIT(buf, value); | |
298 | buffer_append(buffer, buf, 4); | |
299 | } | |
300 | ||
301 | void | |
302 | buffer_put_int64(Buffer *buffer, u_int64_t value) | |
303 | { | |
304 | char buf[8]; | |
305 | ||
306 | PUT_64BIT(buf, value); | |
307 | buffer_append(buffer, buf, 8); | |
308 | } | |
309 | ||
310 | /* | |
311 | * Returns an arbitrary binary string from the buffer. The string cannot | |
312 | * be longer than 256k. The returned value points to memory allocated | |
313 | * with xmalloc; it is the responsibility of the calling function to free | |
314 | * the data. If length_ptr is non-NULL, the length of the returned data | |
315 | * will be stored there. A null character will be automatically appended | |
316 | * to the returned string, and is not counted in length. | |
317 | */ | |
318 | void * | |
319 | buffer_get_string_ret(Buffer *buffer, u_int *length_ptr) | |
320 | { | |
321 | u_char *value; | |
322 | u_int len; | |
323 | ||
324 | /* Get the length. */ | |
325 | len = buffer_get_int(buffer); | |
326 | if (len > 256 * 1024) { | |
327 | error("buffer_get_string_ret: bad string length %u", len); | |
328 | return (NULL); | |
329 | } | |
330 | /* Allocate space for the string. Add one byte for a null character. */ | |
331 | value = xmalloc(len + 1); | |
332 | /* Get the string. */ | |
333 | if (buffer_get_ret(buffer, value, len) == -1) { | |
334 | error("buffer_get_string_ret: buffer_get failed"); | |
335 | xfree(value); | |
336 | return (NULL); | |
337 | } | |
338 | /* Append a null character to make processing easier. */ | |
339 | value[len] = 0; | |
340 | /* Optionally return the length of the string. */ | |
341 | if (length_ptr) | |
342 | *length_ptr = len; | |
343 | return (value); | |
344 | } | |
345 | ||
346 | void * | |
347 | buffer_get_string(Buffer *buffer, u_int *length_ptr) | |
348 | { | |
349 | void *ret; | |
350 | ||
351 | if ((ret = buffer_get_string_ret(buffer, length_ptr)) == NULL) | |
352 | fatal("buffer_get_string: buffer error"); | |
353 | return (ret); | |
354 | } | |
355 | ||
356 | /* | |
357 | * Stores and arbitrary binary string in the buffer. | |
358 | */ | |
359 | void | |
360 | buffer_put_string(Buffer *buffer, const void *buf, u_int len) | |
361 | { | |
362 | buffer_put_int(buffer, len); | |
363 | buffer_append(buffer, buf, len); | |
364 | } | |
365 | void | |
366 | buffer_put_cstring(Buffer *buffer, const char *s) | |
367 | { | |
368 | if (s == NULL) | |
369 | fatal("buffer_put_cstring: s == NULL"); | |
370 | buffer_put_string(buffer, s, strlen(s)); | |
371 | } | |
372 | ||
373 | /* | |
374 | * Returns a character from the buffer (0 - 255). | |
375 | */ | |
376 | int | |
377 | buffer_get_char_ret(char *ret, Buffer *buffer) | |
378 | { | |
379 | if (buffer_get_ret(buffer, ret, 1) == -1) { | |
380 | error("buffer_get_char_ret: buffer_get_ret failed"); | |
381 | return (-1); | |
382 | } | |
383 | return (0); | |
384 | } | |
385 | ||
386 | int | |
387 | buffer_get_char(Buffer *buffer) | |
388 | { | |
389 | char ch; | |
390 | ||
391 | if (buffer_get_char_ret(&ch, buffer) == -1) | |
392 | fatal("buffer_get_char: buffer error"); | |
393 | return (u_char) ch; | |
394 | } | |
395 | ||
396 | /* | |
397 | * Stores a character in the buffer. | |
398 | */ | |
399 | void | |
400 | buffer_put_char(Buffer *buffer, int value) | |
401 | { | |
402 | char ch = value; | |
403 | ||
404 | buffer_append(buffer, &ch, 1); | |
405 | } |