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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 | * This file contains code implementing the packet protocol and communication | |
6 | * with the other side. This same code is used both on client and server side. | |
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, 2001 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 | RCSID("$OpenBSD: packet.c,v 1.72 2001/11/10 13:37:20 markus Exp $"); | |
41 | ||
42 | #include "xmalloc.h" | |
43 | #include "buffer.h" | |
44 | #include "packet.h" | |
45 | #include "bufaux.h" | |
46 | #include "crc32.h" | |
47 | #include "getput.h" | |
48 | ||
49 | #include "compress.h" | |
50 | #include "deattack.h" | |
51 | #include "channels.h" | |
52 | ||
53 | #include "compat.h" | |
54 | #include "ssh1.h" | |
55 | #include "ssh2.h" | |
56 | ||
57 | #include "cipher.h" | |
58 | #include "kex.h" | |
59 | #include "mac.h" | |
60 | #include "log.h" | |
61 | #include "canohost.h" | |
62 | ||
63 | #ifdef PACKET_DEBUG | |
64 | #define DBG(x) x | |
65 | #else | |
66 | #define DBG(x) | |
67 | #endif | |
68 | ||
69 | /* | |
70 | * This variable contains the file descriptors used for communicating with | |
71 | * the other side. connection_in is used for reading; connection_out for | |
72 | * writing. These can be the same descriptor, in which case it is assumed to | |
73 | * be a socket. | |
74 | */ | |
75 | static int connection_in = -1; | |
76 | static int connection_out = -1; | |
77 | ||
78 | /* Protocol flags for the remote side. */ | |
79 | static u_int remote_protocol_flags = 0; | |
80 | ||
81 | /* Encryption context for receiving data. This is only used for decryption. */ | |
82 | static CipherContext receive_context; | |
83 | ||
84 | /* Encryption context for sending data. This is only used for encryption. */ | |
85 | static CipherContext send_context; | |
86 | ||
87 | /* Buffer for raw input data from the socket. */ | |
88 | static Buffer input; | |
89 | ||
90 | /* Buffer for raw output data going to the socket. */ | |
91 | static Buffer output; | |
92 | ||
93 | /* Buffer for the partial outgoing packet being constructed. */ | |
94 | static Buffer outgoing_packet; | |
95 | ||
96 | /* Buffer for the incoming packet currently being processed. */ | |
97 | static Buffer incoming_packet; | |
98 | ||
99 | /* Scratch buffer for packet compression/decompression. */ | |
100 | static Buffer compression_buffer; | |
101 | static int compression_buffer_ready = 0; | |
102 | ||
103 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
104 | static int packet_compression = 0; | |
105 | ||
106 | /* default maximum packet size */ | |
107 | int max_packet_size = 32768; | |
108 | ||
109 | /* Flag indicating whether this module has been initialized. */ | |
110 | static int initialized = 0; | |
111 | ||
112 | /* Set to true if the connection is interactive. */ | |
113 | static int interactive_mode = 0; | |
114 | ||
115 | /* Session key information for Encryption and MAC */ | |
116 | Newkeys *newkeys[MODE_MAX]; | |
117 | ||
118 | /* roundup current message to extra_pad bytes */ | |
119 | static u_char extra_pad = 0; | |
120 | ||
121 | /* | |
122 | * Sets the descriptors used for communication. Disables encryption until | |
123 | * packet_set_encryption_key is called. | |
124 | */ | |
125 | void | |
126 | packet_set_connection(int fd_in, int fd_out) | |
127 | { | |
128 | Cipher *none = cipher_by_name("none"); | |
129 | if (none == NULL) | |
130 | fatal("packet_set_connection: cannot load cipher 'none'"); | |
131 | connection_in = fd_in; | |
132 | connection_out = fd_out; | |
133 | cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0); | |
134 | cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0); | |
135 | newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; | |
136 | if (!initialized) { | |
137 | initialized = 1; | |
138 | buffer_init(&input); | |
139 | buffer_init(&output); | |
140 | buffer_init(&outgoing_packet); | |
141 | buffer_init(&incoming_packet); | |
142 | } | |
143 | /* Kludge: arrange the close function to be called from fatal(). */ | |
144 | fatal_add_cleanup((void (*) (void *)) packet_close, NULL); | |
145 | } | |
146 | ||
147 | /* Returns 1 if remote host is connected via socket, 0 if not. */ | |
148 | ||
149 | int | |
150 | packet_connection_is_on_socket() | |
151 | { | |
152 | struct sockaddr_storage from, to; | |
153 | socklen_t fromlen, tolen; | |
154 | ||
155 | /* filedescriptors in and out are the same, so it's a socket */ | |
156 | if (connection_in == connection_out) | |
157 | return 1; | |
158 | fromlen = sizeof(from); | |
159 | memset(&from, 0, sizeof(from)); | |
160 | if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) | |
161 | return 0; | |
162 | tolen = sizeof(to); | |
163 | memset(&to, 0, sizeof(to)); | |
164 | if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
165 | return 0; | |
166 | if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) | |
167 | return 0; | |
168 | if (from.ss_family != AF_INET && from.ss_family != AF_INET6) | |
169 | return 0; | |
170 | return 1; | |
171 | } | |
172 | ||
173 | /* returns 1 if connection is via ipv4 */ | |
174 | ||
175 | int | |
176 | packet_connection_is_ipv4() | |
177 | { | |
178 | struct sockaddr_storage to; | |
179 | socklen_t tolen = sizeof(to); | |
180 | ||
181 | memset(&to, 0, sizeof(to)); | |
182 | if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) | |
183 | return 0; | |
184 | if (to.ss_family != AF_INET) | |
185 | return 0; | |
186 | return 1; | |
187 | } | |
188 | ||
189 | /* Sets the connection into non-blocking mode. */ | |
190 | ||
191 | void | |
192 | packet_set_nonblocking() | |
193 | { | |
194 | /* Set the socket into non-blocking mode. */ | |
195 | if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) | |
196 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
197 | ||
198 | if (connection_out != connection_in) { | |
199 | if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) | |
200 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
201 | } | |
202 | } | |
203 | ||
204 | /* Returns the socket used for reading. */ | |
205 | ||
206 | int | |
207 | packet_get_connection_in() | |
208 | { | |
209 | return connection_in; | |
210 | } | |
211 | ||
212 | /* Returns the descriptor used for writing. */ | |
213 | ||
214 | int | |
215 | packet_get_connection_out() | |
216 | { | |
217 | return connection_out; | |
218 | } | |
219 | ||
220 | /* Closes the connection and clears and frees internal data structures. */ | |
221 | ||
222 | void | |
223 | packet_close() | |
224 | { | |
225 | if (!initialized) | |
226 | return; | |
227 | initialized = 0; | |
228 | if (connection_in == connection_out) { | |
229 | shutdown(connection_out, SHUT_RDWR); | |
230 | close(connection_out); | |
231 | } else { | |
232 | close(connection_in); | |
233 | close(connection_out); | |
234 | } | |
235 | buffer_free(&input); | |
236 | buffer_free(&output); | |
237 | buffer_free(&outgoing_packet); | |
238 | buffer_free(&incoming_packet); | |
239 | if (compression_buffer_ready) { | |
240 | buffer_free(&compression_buffer); | |
241 | buffer_compress_uninit(); | |
242 | } | |
243 | } | |
244 | ||
245 | /* Sets remote side protocol flags. */ | |
246 | ||
247 | void | |
248 | packet_set_protocol_flags(u_int protocol_flags) | |
249 | { | |
250 | remote_protocol_flags = protocol_flags; | |
251 | } | |
252 | ||
253 | /* Returns the remote protocol flags set earlier by the above function. */ | |
254 | ||
255 | u_int | |
256 | packet_get_protocol_flags() | |
257 | { | |
258 | return remote_protocol_flags; | |
259 | } | |
260 | ||
261 | /* | |
262 | * Starts packet compression from the next packet on in both directions. | |
263 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
264 | */ | |
265 | ||
266 | static void | |
267 | packet_init_compression(void) | |
268 | { | |
269 | if (compression_buffer_ready == 1) | |
270 | return; | |
271 | compression_buffer_ready = 1; | |
272 | buffer_init(&compression_buffer); | |
273 | } | |
274 | ||
275 | void | |
276 | packet_start_compression(int level) | |
277 | { | |
278 | if (packet_compression && !compat20) | |
279 | fatal("Compression already enabled."); | |
280 | packet_compression = 1; | |
281 | packet_init_compression(); | |
282 | buffer_compress_init_send(level); | |
283 | buffer_compress_init_recv(); | |
284 | } | |
285 | ||
286 | /* | |
287 | * Causes any further packets to be encrypted using the given key. The same | |
288 | * key is used for both sending and reception. However, both directions are | |
289 | * encrypted independently of each other. | |
290 | */ | |
291 | void | |
292 | packet_set_encryption_key(const u_char *key, u_int keylen, | |
293 | int number) | |
294 | { | |
295 | Cipher *cipher = cipher_by_number(number); | |
296 | if (cipher == NULL) | |
297 | fatal("packet_set_encryption_key: unknown cipher number %d", number); | |
298 | if (keylen < 20) | |
299 | fatal("packet_set_encryption_key: keylen too small: %d", keylen); | |
300 | cipher_init(&receive_context, cipher, key, keylen, NULL, 0); | |
301 | cipher_init(&send_context, cipher, key, keylen, NULL, 0); | |
302 | } | |
303 | ||
304 | /* Start constructing a packet to send. */ | |
305 | void | |
306 | packet_start(u_char type) | |
307 | { | |
308 | u_char buf[9]; | |
309 | int len; | |
310 | ||
311 | DBG(debug("packet_start[%d]", type)); | |
312 | len = compat20 ? 6 : 9; | |
313 | memset(buf, 0, len - 1); | |
314 | buf[len - 1] = type; | |
315 | buffer_clear(&outgoing_packet); | |
316 | buffer_append(&outgoing_packet, buf, len); | |
317 | } | |
318 | ||
319 | /* Append payload. */ | |
320 | void | |
321 | packet_put_char(int value) | |
322 | { | |
323 | char ch = value; | |
324 | buffer_append(&outgoing_packet, &ch, 1); | |
325 | } | |
326 | void | |
327 | packet_put_int(u_int value) | |
328 | { | |
329 | buffer_put_int(&outgoing_packet, value); | |
330 | } | |
331 | void | |
332 | packet_put_string(const char *buf, u_int len) | |
333 | { | |
334 | buffer_put_string(&outgoing_packet, buf, len); | |
335 | } | |
336 | void | |
337 | packet_put_cstring(const char *str) | |
338 | { | |
339 | buffer_put_cstring(&outgoing_packet, str); | |
340 | } | |
341 | void | |
342 | packet_put_raw(const char *buf, u_int len) | |
343 | { | |
344 | buffer_append(&outgoing_packet, buf, len); | |
345 | } | |
346 | void | |
347 | packet_put_bignum(BIGNUM * value) | |
348 | { | |
349 | buffer_put_bignum(&outgoing_packet, value); | |
350 | } | |
351 | void | |
352 | packet_put_bignum2(BIGNUM * value) | |
353 | { | |
354 | buffer_put_bignum2(&outgoing_packet, value); | |
355 | } | |
356 | ||
357 | /* | |
358 | * Finalizes and sends the packet. If the encryption key has been set, | |
359 | * encrypts the packet before sending. | |
360 | */ | |
361 | ||
362 | static void | |
363 | packet_send1(void) | |
364 | { | |
365 | char buf[8], *cp; | |
366 | int i, padding, len; | |
367 | u_int checksum; | |
368 | u_int32_t rand = 0; | |
369 | ||
370 | /* | |
371 | * If using packet compression, compress the payload of the outgoing | |
372 | * packet. | |
373 | */ | |
374 | if (packet_compression) { | |
375 | buffer_clear(&compression_buffer); | |
376 | /* Skip padding. */ | |
377 | buffer_consume(&outgoing_packet, 8); | |
378 | /* padding */ | |
379 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
380 | buffer_compress(&outgoing_packet, &compression_buffer); | |
381 | buffer_clear(&outgoing_packet); | |
382 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
383 | buffer_len(&compression_buffer)); | |
384 | } | |
385 | /* Compute packet length without padding (add checksum, remove padding). */ | |
386 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
387 | ||
388 | /* Insert padding. Initialized to zero in packet_start1() */ | |
389 | padding = 8 - len % 8; | |
390 | if (send_context.cipher->number != SSH_CIPHER_NONE) { | |
391 | cp = buffer_ptr(&outgoing_packet); | |
392 | for (i = 0; i < padding; i++) { | |
393 | if (i % 4 == 0) | |
394 | rand = arc4random(); | |
395 | cp[7 - i] = rand & 0xff; | |
396 | rand >>= 8; | |
397 | } | |
398 | } | |
399 | buffer_consume(&outgoing_packet, 8 - padding); | |
400 | ||
401 | /* Add check bytes. */ | |
402 | checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet), | |
403 | buffer_len(&outgoing_packet)); | |
404 | PUT_32BIT(buf, checksum); | |
405 | buffer_append(&outgoing_packet, buf, 4); | |
406 | ||
407 | #ifdef PACKET_DEBUG | |
408 | fprintf(stderr, "packet_send plain: "); | |
409 | buffer_dump(&outgoing_packet); | |
410 | #endif | |
411 | ||
412 | /* Append to output. */ | |
413 | PUT_32BIT(buf, len); | |
414 | buffer_append(&output, buf, 4); | |
415 | buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); | |
416 | cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
417 | buffer_len(&outgoing_packet)); | |
418 | ||
419 | #ifdef PACKET_DEBUG | |
420 | fprintf(stderr, "encrypted: "); | |
421 | buffer_dump(&output); | |
422 | #endif | |
423 | ||
424 | buffer_clear(&outgoing_packet); | |
425 | ||
426 | /* | |
427 | * Note that the packet is now only buffered in output. It won\'t be | |
428 | * actually sent until packet_write_wait or packet_write_poll is | |
429 | * called. | |
430 | */ | |
431 | } | |
432 | ||
433 | static void | |
434 | set_newkeys(int mode) | |
435 | { | |
436 | Enc *enc; | |
437 | Mac *mac; | |
438 | Comp *comp; | |
439 | CipherContext *cc; | |
440 | ||
441 | debug("newkeys: mode %d", mode); | |
442 | ||
443 | cc = (mode == MODE_OUT) ? &send_context : &receive_context; | |
444 | if (newkeys[mode] != NULL) { | |
445 | debug("newkeys: rekeying"); | |
446 | /* todo: free old keys, reset compression/cipher-ctxt; */ | |
447 | memset(cc, 0, sizeof(*cc)); | |
448 | enc = &newkeys[mode]->enc; | |
449 | mac = &newkeys[mode]->mac; | |
450 | comp = &newkeys[mode]->comp; | |
451 | memset(mac->key, 0, mac->key_len); | |
452 | xfree(enc->name); | |
453 | xfree(enc->iv); | |
454 | xfree(enc->key); | |
455 | xfree(mac->name); | |
456 | xfree(mac->key); | |
457 | xfree(comp->name); | |
458 | xfree(newkeys[mode]); | |
459 | } | |
460 | newkeys[mode] = kex_get_newkeys(mode); | |
461 | if (newkeys[mode] == NULL) | |
462 | fatal("newkeys: no keys for mode %d", mode); | |
463 | enc = &newkeys[mode]->enc; | |
464 | mac = &newkeys[mode]->mac; | |
465 | comp = &newkeys[mode]->comp; | |
466 | if (mac->md != NULL) | |
467 | mac->enabled = 1; | |
468 | DBG(debug("cipher_init_context: %d", mode)); | |
469 | cipher_init(cc, enc->cipher, enc->key, enc->cipher->key_len, | |
470 | enc->iv, enc->cipher->block_size); | |
471 | memset(enc->iv, 0, enc->cipher->block_size); | |
472 | memset(enc->key, 0, enc->cipher->key_len); | |
473 | if (comp->type != 0 && comp->enabled == 0) { | |
474 | packet_init_compression(); | |
475 | if (mode == MODE_OUT) | |
476 | buffer_compress_init_send(6); | |
477 | else | |
478 | buffer_compress_init_recv(); | |
479 | comp->enabled = 1; | |
480 | } | |
481 | } | |
482 | ||
483 | /* | |
484 | * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) | |
485 | */ | |
486 | static void | |
487 | packet_send2(void) | |
488 | { | |
489 | static u_int32_t seqnr = 0; | |
490 | u_char type, *ucp, *macbuf = NULL; | |
491 | u_char padlen, pad; | |
492 | char *cp; | |
493 | u_int packet_length = 0; | |
494 | u_int i, len; | |
495 | u_int32_t rand = 0; | |
496 | Enc *enc = NULL; | |
497 | Mac *mac = NULL; | |
498 | Comp *comp = NULL; | |
499 | int block_size; | |
500 | ||
501 | if (newkeys[MODE_OUT] != NULL) { | |
502 | enc = &newkeys[MODE_OUT]->enc; | |
503 | mac = &newkeys[MODE_OUT]->mac; | |
504 | comp = &newkeys[MODE_OUT]->comp; | |
505 | } | |
506 | block_size = enc ? enc->cipher->block_size : 8; | |
507 | ||
508 | ucp = (u_char *) buffer_ptr(&outgoing_packet); | |
509 | type = ucp[5]; | |
510 | ||
511 | #ifdef PACKET_DEBUG | |
512 | fprintf(stderr, "plain: "); | |
513 | buffer_dump(&outgoing_packet); | |
514 | #endif | |
515 | ||
516 | if (comp && comp->enabled) { | |
517 | len = buffer_len(&outgoing_packet); | |
518 | /* skip header, compress only payload */ | |
519 | buffer_consume(&outgoing_packet, 5); | |
520 | buffer_clear(&compression_buffer); | |
521 | buffer_compress(&outgoing_packet, &compression_buffer); | |
522 | buffer_clear(&outgoing_packet); | |
523 | buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); | |
524 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
525 | buffer_len(&compression_buffer)); | |
526 | DBG(debug("compression: raw %d compressed %d", len, | |
527 | buffer_len(&outgoing_packet))); | |
528 | } | |
529 | ||
530 | /* sizeof (packet_len + pad_len + payload) */ | |
531 | len = buffer_len(&outgoing_packet); | |
532 | ||
533 | /* | |
534 | * calc size of padding, alloc space, get random data, | |
535 | * minimum padding is 4 bytes | |
536 | */ | |
537 | padlen = block_size - (len % block_size); | |
538 | if (padlen < 4) | |
539 | padlen += block_size; | |
540 | if (extra_pad) { | |
541 | /* will wrap if extra_pad+padlen > 255 */ | |
542 | extra_pad = roundup(extra_pad, block_size); | |
543 | pad = extra_pad - ((len + padlen) % extra_pad); | |
544 | debug("packet_send2: adding %d (len %d padlen %d extra_pad %d)", | |
545 | pad, len, padlen, extra_pad); | |
546 | padlen += pad; | |
547 | extra_pad = 0; | |
548 | } | |
549 | buffer_append_space(&outgoing_packet, &cp, padlen); | |
550 | if (enc && enc->cipher->number != SSH_CIPHER_NONE) { | |
551 | /* random padding */ | |
552 | for (i = 0; i < padlen; i++) { | |
553 | if (i % 4 == 0) | |
554 | rand = arc4random(); | |
555 | cp[i] = rand & 0xff; | |
556 | rand >>= 8; | |
557 | } | |
558 | } else { | |
559 | /* clear padding */ | |
560 | memset(cp, 0, padlen); | |
561 | } | |
562 | /* packet_length includes payload, padding and padding length field */ | |
563 | packet_length = buffer_len(&outgoing_packet) - 4; | |
564 | ucp = (u_char *)buffer_ptr(&outgoing_packet); | |
565 | PUT_32BIT(ucp, packet_length); | |
566 | ucp[4] = padlen; | |
567 | DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); | |
568 | ||
569 | /* compute MAC over seqnr and packet(length fields, payload, padding) */ | |
570 | if (mac && mac->enabled) { | |
571 | macbuf = mac_compute(mac, seqnr, | |
572 | (u_char *) buffer_ptr(&outgoing_packet), | |
573 | buffer_len(&outgoing_packet)); | |
574 | DBG(debug("done calc MAC out #%d", seqnr)); | |
575 | } | |
576 | /* encrypt packet and append to output buffer. */ | |
577 | buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); | |
578 | cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
579 | buffer_len(&outgoing_packet)); | |
580 | /* append unencrypted MAC */ | |
581 | if (mac && mac->enabled) | |
582 | buffer_append(&output, (char *)macbuf, mac->mac_len); | |
583 | #ifdef PACKET_DEBUG | |
584 | fprintf(stderr, "encrypted: "); | |
585 | buffer_dump(&output); | |
586 | #endif | |
587 | /* increment sequence number for outgoing packets */ | |
588 | if (++seqnr == 0) | |
589 | log("outgoing seqnr wraps around"); | |
590 | buffer_clear(&outgoing_packet); | |
591 | ||
592 | if (type == SSH2_MSG_NEWKEYS) | |
593 | set_newkeys(MODE_OUT); | |
594 | } | |
595 | ||
596 | void | |
597 | packet_send() | |
598 | { | |
599 | if (compat20) | |
600 | packet_send2(); | |
601 | else | |
602 | packet_send1(); | |
603 | DBG(debug("packet_send done")); | |
604 | } | |
605 | ||
606 | /* | |
607 | * Waits until a packet has been received, and returns its type. Note that | |
608 | * no other data is processed until this returns, so this function should not | |
609 | * be used during the interactive session. | |
610 | */ | |
611 | ||
612 | int | |
613 | packet_read(int *payload_len_ptr) | |
614 | { | |
615 | int type, len; | |
616 | fd_set *setp; | |
617 | char buf[8192]; | |
618 | DBG(debug("packet_read()")); | |
619 | ||
620 | setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * | |
621 | sizeof(fd_mask)); | |
622 | ||
623 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
624 | packet_write_wait(); | |
625 | ||
626 | /* Stay in the loop until we have received a complete packet. */ | |
627 | for (;;) { | |
628 | /* Try to read a packet from the buffer. */ | |
629 | type = packet_read_poll(payload_len_ptr); | |
630 | if (!compat20 && ( | |
631 | type == SSH_SMSG_SUCCESS | |
632 | || type == SSH_SMSG_FAILURE | |
633 | || type == SSH_CMSG_EOF | |
634 | || type == SSH_CMSG_EXIT_CONFIRMATION)) | |
635 | packet_integrity_check(*payload_len_ptr, 0, type); | |
636 | /* If we got a packet, return it. */ | |
637 | if (type != SSH_MSG_NONE) { | |
638 | xfree(setp); | |
639 | return type; | |
640 | } | |
641 | /* | |
642 | * Otherwise, wait for some data to arrive, add it to the | |
643 | * buffer, and try again. | |
644 | */ | |
645 | memset(setp, 0, howmany(connection_in + 1, NFDBITS) * | |
646 | sizeof(fd_mask)); | |
647 | FD_SET(connection_in, setp); | |
648 | ||
649 | /* Wait for some data to arrive. */ | |
650 | while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && | |
651 | (errno == EAGAIN || errno == EINTR)) | |
652 | ; | |
653 | ||
654 | /* Read data from the socket. */ | |
655 | len = read(connection_in, buf, sizeof(buf)); | |
656 | if (len == 0) { | |
657 | log("Connection closed by %.200s", get_remote_ipaddr()); | |
658 | fatal_cleanup(); | |
659 | } | |
660 | if (len < 0) | |
661 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
662 | /* Append it to the buffer. */ | |
663 | packet_process_incoming(buf, len); | |
664 | } | |
665 | /* NOTREACHED */ | |
666 | } | |
667 | ||
668 | /* | |
669 | * Waits until a packet has been received, verifies that its type matches | |
670 | * that given, and gives a fatal error and exits if there is a mismatch. | |
671 | */ | |
672 | ||
673 | void | |
674 | packet_read_expect(int *payload_len_ptr, int expected_type) | |
675 | { | |
676 | int type; | |
677 | ||
678 | type = packet_read(payload_len_ptr); | |
679 | if (type != expected_type) | |
680 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
681 | expected_type, type); | |
682 | } | |
683 | ||
684 | /* Checks if a full packet is available in the data received so far via | |
685 | * packet_process_incoming. If so, reads the packet; otherwise returns | |
686 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
687 | * | |
688 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
689 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
690 | * to higher levels. | |
691 | * | |
692 | * The returned payload_len does include space consumed by: | |
693 | * Packet length | |
694 | * Padding | |
695 | * Packet type | |
696 | * Check bytes | |
697 | */ | |
698 | ||
699 | static int | |
700 | packet_read_poll1(int *payload_len_ptr) | |
701 | { | |
702 | u_int len, padded_len; | |
703 | u_char *ucp, type; | |
704 | char *cp; | |
705 | u_int checksum, stored_checksum; | |
706 | ||
707 | /* Check if input size is less than minimum packet size. */ | |
708 | if (buffer_len(&input) < 4 + 8) | |
709 | return SSH_MSG_NONE; | |
710 | /* Get length of incoming packet. */ | |
711 | ucp = (u_char *) buffer_ptr(&input); | |
712 | len = GET_32BIT(ucp); | |
713 | if (len < 1 + 2 + 2 || len > 256 * 1024) | |
714 | packet_disconnect("Bad packet length %d.", len); | |
715 | padded_len = (len + 8) & ~7; | |
716 | ||
717 | /* Check if the packet has been entirely received. */ | |
718 | if (buffer_len(&input) < 4 + padded_len) | |
719 | return SSH_MSG_NONE; | |
720 | ||
721 | /* The entire packet is in buffer. */ | |
722 | ||
723 | /* Consume packet length. */ | |
724 | buffer_consume(&input, 4); | |
725 | ||
726 | /* | |
727 | * Cryptographic attack detector for ssh | |
728 | * (C)1998 CORE-SDI, Buenos Aires Argentina | |
729 | * Ariel Futoransky(futo@core-sdi.com) | |
730 | */ | |
731 | if (receive_context.cipher->number != SSH_CIPHER_NONE && | |
732 | detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) | |
733 | packet_disconnect("crc32 compensation attack: network attack detected"); | |
734 | ||
735 | /* Decrypt data to incoming_packet. */ | |
736 | buffer_clear(&incoming_packet); | |
737 | buffer_append_space(&incoming_packet, &cp, padded_len); | |
738 | cipher_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
739 | ||
740 | buffer_consume(&input, padded_len); | |
741 | ||
742 | #ifdef PACKET_DEBUG | |
743 | fprintf(stderr, "read_poll plain: "); | |
744 | buffer_dump(&incoming_packet); | |
745 | #endif | |
746 | ||
747 | /* Compute packet checksum. */ | |
748 | checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet), | |
749 | buffer_len(&incoming_packet) - 4); | |
750 | ||
751 | /* Skip padding. */ | |
752 | buffer_consume(&incoming_packet, 8 - len % 8); | |
753 | ||
754 | /* Test check bytes. */ | |
755 | if (len != buffer_len(&incoming_packet)) | |
756 | packet_disconnect("packet_read_poll: len %d != buffer_len %d.", | |
757 | len, buffer_len(&incoming_packet)); | |
758 | ||
759 | ucp = (u_char *) buffer_ptr(&incoming_packet) + len - 4; | |
760 | stored_checksum = GET_32BIT(ucp); | |
761 | if (checksum != stored_checksum) | |
762 | packet_disconnect("Corrupted check bytes on input."); | |
763 | buffer_consume_end(&incoming_packet, 4); | |
764 | ||
765 | if (packet_compression) { | |
766 | buffer_clear(&compression_buffer); | |
767 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
768 | buffer_clear(&incoming_packet); | |
769 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
770 | buffer_len(&compression_buffer)); | |
771 | } | |
772 | type = buffer_get_char(&incoming_packet); | |
773 | *payload_len_ptr = buffer_len(&incoming_packet); | |
774 | return type; | |
775 | } | |
776 | ||
777 | static int | |
778 | packet_read_poll2(int *payload_len_ptr) | |
779 | { | |
780 | static u_int32_t seqnr = 0; | |
781 | static u_int packet_length = 0; | |
782 | u_int padlen, need; | |
783 | u_char *macbuf, *ucp, type; | |
784 | char *cp; | |
785 | int maclen, block_size; | |
786 | Enc *enc = NULL; | |
787 | Mac *mac = NULL; | |
788 | Comp *comp = NULL; | |
789 | ||
790 | if (newkeys[MODE_IN] != NULL) { | |
791 | enc = &newkeys[MODE_IN]->enc; | |
792 | mac = &newkeys[MODE_IN]->mac; | |
793 | comp = &newkeys[MODE_IN]->comp; | |
794 | } | |
795 | maclen = mac && mac->enabled ? mac->mac_len : 0; | |
796 | block_size = enc ? enc->cipher->block_size : 8; | |
797 | ||
798 | if (packet_length == 0) { | |
799 | /* | |
800 | * check if input size is less than the cipher block size, | |
801 | * decrypt first block and extract length of incoming packet | |
802 | */ | |
803 | if (buffer_len(&input) < block_size) | |
804 | return SSH_MSG_NONE; | |
805 | buffer_clear(&incoming_packet); | |
806 | buffer_append_space(&incoming_packet, &cp, block_size); | |
807 | cipher_decrypt(&receive_context, cp, buffer_ptr(&input), | |
808 | block_size); | |
809 | ucp = (u_char *) buffer_ptr(&incoming_packet); | |
810 | packet_length = GET_32BIT(ucp); | |
811 | if (packet_length < 1 + 4 || packet_length > 256 * 1024) { | |
812 | buffer_dump(&incoming_packet); | |
813 | packet_disconnect("Bad packet length %d.", packet_length); | |
814 | } | |
815 | DBG(debug("input: packet len %d", packet_length+4)); | |
816 | buffer_consume(&input, block_size); | |
817 | } | |
818 | /* we have a partial packet of block_size bytes */ | |
819 | need = 4 + packet_length - block_size; | |
820 | DBG(debug("partial packet %d, need %d, maclen %d", block_size, | |
821 | need, maclen)); | |
822 | if (need % block_size != 0) | |
823 | fatal("padding error: need %d block %d mod %d", | |
824 | need, block_size, need % block_size); | |
825 | /* | |
826 | * check if the entire packet has been received and | |
827 | * decrypt into incoming_packet | |
828 | */ | |
829 | if (buffer_len(&input) < need + maclen) | |
830 | return SSH_MSG_NONE; | |
831 | #ifdef PACKET_DEBUG | |
832 | fprintf(stderr, "read_poll enc/full: "); | |
833 | buffer_dump(&input); | |
834 | #endif | |
835 | buffer_append_space(&incoming_packet, &cp, need); | |
836 | cipher_decrypt(&receive_context, cp, buffer_ptr(&input), need); | |
837 | buffer_consume(&input, need); | |
838 | /* | |
839 | * compute MAC over seqnr and packet, | |
840 | * increment sequence number for incoming packet | |
841 | */ | |
842 | if (mac && mac->enabled) { | |
843 | macbuf = mac_compute(mac, seqnr, | |
844 | (u_char *) buffer_ptr(&incoming_packet), | |
845 | buffer_len(&incoming_packet)); | |
846 | if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) | |
847 | packet_disconnect("Corrupted MAC on input."); | |
848 | DBG(debug("MAC #%d ok", seqnr)); | |
849 | buffer_consume(&input, mac->mac_len); | |
850 | } | |
851 | if (++seqnr == 0) | |
852 | log("incoming seqnr wraps around"); | |
853 | ||
854 | /* get padlen */ | |
855 | cp = buffer_ptr(&incoming_packet) + 4; | |
856 | padlen = (u_char) *cp; | |
857 | DBG(debug("input: padlen %d", padlen)); | |
858 | if (padlen < 4) | |
859 | packet_disconnect("Corrupted padlen %d on input.", padlen); | |
860 | ||
861 | /* skip packet size + padlen, discard padding */ | |
862 | buffer_consume(&incoming_packet, 4 + 1); | |
863 | buffer_consume_end(&incoming_packet, padlen); | |
864 | ||
865 | DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); | |
866 | if (comp && comp->enabled) { | |
867 | buffer_clear(&compression_buffer); | |
868 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
869 | buffer_clear(&incoming_packet); | |
870 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
871 | buffer_len(&compression_buffer)); | |
872 | DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet))); | |
873 | } | |
874 | /* | |
875 | * get packet type, implies consume. | |
876 | * return length of payload (without type field) | |
877 | */ | |
878 | type = buffer_get_char(&incoming_packet); | |
879 | if (type == SSH2_MSG_NEWKEYS) | |
880 | set_newkeys(MODE_IN); | |
881 | *payload_len_ptr = buffer_len(&incoming_packet); | |
882 | #ifdef PACKET_DEBUG | |
883 | fprintf(stderr, "read/plain[%d]:\r\n", type); | |
884 | buffer_dump(&incoming_packet); | |
885 | #endif | |
886 | /* reset for next packet */ | |
887 | packet_length = 0; | |
888 | return type; | |
889 | } | |
890 | ||
891 | int | |
892 | packet_read_poll(int *payload_len_ptr) | |
893 | { | |
894 | int reason; | |
895 | u_char type; | |
896 | char *msg; | |
897 | ||
898 | for (;;) { | |
899 | if (compat20) { | |
900 | type = packet_read_poll2(payload_len_ptr); | |
901 | if (type) | |
902 | DBG(debug("received packet type %d", type)); | |
903 | switch(type) { | |
904 | case SSH2_MSG_IGNORE: | |
905 | break; | |
906 | case SSH2_MSG_DEBUG: | |
907 | packet_get_char(); | |
908 | msg = packet_get_string(NULL); | |
909 | debug("Remote: %.900s", msg); | |
910 | xfree(msg); | |
911 | msg = packet_get_string(NULL); | |
912 | xfree(msg); | |
913 | break; | |
914 | case SSH2_MSG_DISCONNECT: | |
915 | reason = packet_get_int(); | |
916 | msg = packet_get_string(NULL); | |
917 | log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(), | |
918 | reason, msg); | |
919 | xfree(msg); | |
920 | fatal_cleanup(); | |
921 | break; | |
922 | default: | |
923 | return type; | |
924 | break; | |
925 | } | |
926 | } else { | |
927 | type = packet_read_poll1(payload_len_ptr); | |
928 | switch(type) { | |
929 | case SSH_MSG_IGNORE: | |
930 | break; | |
931 | case SSH_MSG_DEBUG: | |
932 | msg = packet_get_string(NULL); | |
933 | debug("Remote: %.900s", msg); | |
934 | xfree(msg); | |
935 | break; | |
936 | case SSH_MSG_DISCONNECT: | |
937 | msg = packet_get_string(NULL); | |
938 | log("Received disconnect from %s: %.400s", get_remote_ipaddr(), | |
939 | msg); | |
940 | fatal_cleanup(); | |
941 | xfree(msg); | |
942 | break; | |
943 | default: | |
944 | if (type) | |
945 | DBG(debug("received packet type %d", type)); | |
946 | return type; | |
947 | break; | |
948 | } | |
949 | } | |
950 | } | |
951 | } | |
952 | ||
953 | /* | |
954 | * Buffers the given amount of input characters. This is intended to be used | |
955 | * together with packet_read_poll. | |
956 | */ | |
957 | ||
958 | void | |
959 | packet_process_incoming(const char *buf, u_int len) | |
960 | { | |
961 | buffer_append(&input, buf, len); | |
962 | } | |
963 | ||
964 | /* Returns a character from the packet. */ | |
965 | ||
966 | u_int | |
967 | packet_get_char() | |
968 | { | |
969 | char ch; | |
970 | buffer_get(&incoming_packet, &ch, 1); | |
971 | return (u_char) ch; | |
972 | } | |
973 | ||
974 | /* Returns an integer from the packet data. */ | |
975 | ||
976 | u_int | |
977 | packet_get_int() | |
978 | { | |
979 | return buffer_get_int(&incoming_packet); | |
980 | } | |
981 | ||
982 | /* | |
983 | * Returns an arbitrary precision integer from the packet data. The integer | |
984 | * must have been initialized before this call. | |
985 | */ | |
986 | ||
987 | void | |
988 | packet_get_bignum(BIGNUM * value, int *length_ptr) | |
989 | { | |
990 | *length_ptr = buffer_get_bignum(&incoming_packet, value); | |
991 | } | |
992 | ||
993 | void | |
994 | packet_get_bignum2(BIGNUM * value, int *length_ptr) | |
995 | { | |
996 | *length_ptr = buffer_get_bignum2(&incoming_packet, value); | |
997 | } | |
998 | ||
999 | char * | |
1000 | packet_get_raw(int *length_ptr) | |
1001 | { | |
1002 | int bytes = buffer_len(&incoming_packet); | |
1003 | if (length_ptr != NULL) | |
1004 | *length_ptr = bytes; | |
1005 | return buffer_ptr(&incoming_packet); | |
1006 | } | |
1007 | ||
1008 | int | |
1009 | packet_remaining(void) | |
1010 | { | |
1011 | return buffer_len(&incoming_packet); | |
1012 | } | |
1013 | ||
1014 | /* | |
1015 | * Returns a string from the packet data. The string is allocated using | |
1016 | * xmalloc; it is the responsibility of the calling program to free it when | |
1017 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
1018 | * integer into which the length of the string is stored. | |
1019 | */ | |
1020 | ||
1021 | char * | |
1022 | packet_get_string(u_int *length_ptr) | |
1023 | { | |
1024 | return buffer_get_string(&incoming_packet, length_ptr); | |
1025 | } | |
1026 | ||
1027 | /* | |
1028 | * Sends a diagnostic message from the server to the client. This message | |
1029 | * can be sent at any time (but not while constructing another message). The | |
1030 | * message is printed immediately, but only if the client is being executed | |
1031 | * in verbose mode. These messages are primarily intended to ease debugging | |
1032 | * authentication problems. The length of the formatted message must not | |
1033 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
1034 | */ | |
1035 | ||
1036 | void | |
1037 | packet_send_debug(const char *fmt,...) | |
1038 | { | |
1039 | char buf[1024]; | |
1040 | va_list args; | |
1041 | ||
1042 | if (compat20 && (datafellows & SSH_BUG_DEBUG)) | |
1043 | return; | |
1044 | ||
1045 | va_start(args, fmt); | |
1046 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1047 | va_end(args); | |
1048 | ||
1049 | if (compat20) { | |
1050 | packet_start(SSH2_MSG_DEBUG); | |
1051 | packet_put_char(0); /* bool: always display */ | |
1052 | packet_put_cstring(buf); | |
1053 | packet_put_cstring(""); | |
1054 | } else { | |
1055 | packet_start(SSH_MSG_DEBUG); | |
1056 | packet_put_cstring(buf); | |
1057 | } | |
1058 | packet_send(); | |
1059 | packet_write_wait(); | |
1060 | } | |
1061 | ||
1062 | /* | |
1063 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
1064 | * connection, and exits. This function never returns. The error message | |
1065 | * should not contain a newline. The length of the formatted message must | |
1066 | * not exceed 1024 bytes. | |
1067 | */ | |
1068 | ||
1069 | void | |
1070 | packet_disconnect(const char *fmt,...) | |
1071 | { | |
1072 | char buf[1024]; | |
1073 | va_list args; | |
1074 | static int disconnecting = 0; | |
1075 | if (disconnecting) /* Guard against recursive invocations. */ | |
1076 | fatal("packet_disconnect called recursively."); | |
1077 | disconnecting = 1; | |
1078 | ||
1079 | /* | |
1080 | * Format the message. Note that the caller must make sure the | |
1081 | * message is of limited size. | |
1082 | */ | |
1083 | va_start(args, fmt); | |
1084 | vsnprintf(buf, sizeof(buf), fmt, args); | |
1085 | va_end(args); | |
1086 | ||
1087 | /* Send the disconnect message to the other side, and wait for it to get sent. */ | |
1088 | if (compat20) { | |
1089 | packet_start(SSH2_MSG_DISCONNECT); | |
1090 | packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); | |
1091 | packet_put_cstring(buf); | |
1092 | packet_put_cstring(""); | |
1093 | } else { | |
1094 | packet_start(SSH_MSG_DISCONNECT); | |
1095 | packet_put_cstring(buf); | |
1096 | } | |
1097 | packet_send(); | |
1098 | packet_write_wait(); | |
1099 | ||
1100 | /* Stop listening for connections. */ | |
1101 | channel_close_all(); | |
1102 | ||
1103 | /* Close the connection. */ | |
1104 | packet_close(); | |
1105 | ||
1106 | /* Display the error locally and exit. */ | |
1107 | log("Disconnecting: %.100s", buf); | |
1108 | fatal_cleanup(); | |
1109 | } | |
1110 | ||
1111 | /* Checks if there is any buffered output, and tries to write some of the output. */ | |
1112 | ||
1113 | void | |
1114 | packet_write_poll() | |
1115 | { | |
1116 | int len = buffer_len(&output); | |
1117 | if (len > 0) { | |
1118 | len = write(connection_out, buffer_ptr(&output), len); | |
1119 | if (len <= 0) { | |
1120 | if (errno == EAGAIN) | |
1121 | return; | |
1122 | else | |
1123 | fatal("Write failed: %.100s", strerror(errno)); | |
1124 | } | |
1125 | buffer_consume(&output, len); | |
1126 | } | |
1127 | } | |
1128 | ||
1129 | /* | |
1130 | * Calls packet_write_poll repeatedly until all pending output data has been | |
1131 | * written. | |
1132 | */ | |
1133 | ||
1134 | void | |
1135 | packet_write_wait() | |
1136 | { | |
1137 | fd_set *setp; | |
1138 | ||
1139 | setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * | |
1140 | sizeof(fd_mask)); | |
1141 | packet_write_poll(); | |
1142 | while (packet_have_data_to_write()) { | |
1143 | memset(setp, 0, howmany(connection_out + 1, NFDBITS) * | |
1144 | sizeof(fd_mask)); | |
1145 | FD_SET(connection_out, setp); | |
1146 | while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && | |
1147 | (errno == EAGAIN || errno == EINTR)) | |
1148 | ; | |
1149 | packet_write_poll(); | |
1150 | } | |
1151 | xfree(setp); | |
1152 | } | |
1153 | ||
1154 | /* Returns true if there is buffered data to write to the connection. */ | |
1155 | ||
1156 | int | |
1157 | packet_have_data_to_write() | |
1158 | { | |
1159 | return buffer_len(&output) != 0; | |
1160 | } | |
1161 | ||
1162 | /* Returns true if there is not too much data to write to the connection. */ | |
1163 | ||
1164 | int | |
1165 | packet_not_very_much_data_to_write() | |
1166 | { | |
1167 | if (interactive_mode) | |
1168 | return buffer_len(&output) < 16384; | |
1169 | else | |
1170 | return buffer_len(&output) < 128 * 1024; | |
1171 | } | |
1172 | ||
1173 | /* Informs that the current session is interactive. Sets IP flags for that. */ | |
1174 | ||
1175 | void | |
1176 | packet_set_interactive(int interactive) | |
1177 | { | |
1178 | static int called = 0; | |
1179 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1180 | int lowdelay = IPTOS_LOWDELAY; | |
1181 | int throughput = IPTOS_THROUGHPUT; | |
1182 | #endif | |
1183 | int on = 1; | |
1184 | ||
1185 | if (called) | |
1186 | return; | |
1187 | called = 1; | |
1188 | ||
1189 | /* Record that we are in interactive mode. */ | |
1190 | interactive_mode = interactive; | |
1191 | ||
1192 | /* Only set socket options if using a socket. */ | |
1193 | if (!packet_connection_is_on_socket()) | |
1194 | return; | |
1195 | /* | |
1196 | * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only | |
1197 | */ | |
1198 | if (interactive) { | |
1199 | /* | |
1200 | * Set IP options for an interactive connection. Use | |
1201 | * IPTOS_LOWDELAY and TCP_NODELAY. | |
1202 | */ | |
1203 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1204 | if (packet_connection_is_ipv4()) { | |
1205 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, | |
1206 | (void *) &lowdelay, sizeof(lowdelay)) < 0) | |
1207 | error("setsockopt IPTOS_LOWDELAY: %.100s", | |
1208 | strerror(errno)); | |
1209 | } | |
1210 | #endif | |
1211 | if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, | |
1212 | sizeof(on)) < 0) | |
1213 | error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); | |
1214 | } else if (packet_connection_is_ipv4()) { | |
1215 | /* | |
1216 | * Set IP options for a non-interactive connection. Use | |
1217 | * IPTOS_THROUGHPUT. | |
1218 | */ | |
1219 | #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) | |
1220 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput, | |
1221 | sizeof(throughput)) < 0) | |
1222 | error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); | |
1223 | #endif | |
1224 | } | |
1225 | } | |
1226 | ||
1227 | /* Returns true if the current connection is interactive. */ | |
1228 | ||
1229 | int | |
1230 | packet_is_interactive() | |
1231 | { | |
1232 | return interactive_mode; | |
1233 | } | |
1234 | ||
1235 | int | |
1236 | packet_set_maxsize(int s) | |
1237 | { | |
1238 | static int called = 0; | |
1239 | if (called) { | |
1240 | log("packet_set_maxsize: called twice: old %d new %d", | |
1241 | max_packet_size, s); | |
1242 | return -1; | |
1243 | } | |
1244 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
1245 | log("packet_set_maxsize: bad size %d", s); | |
1246 | return -1; | |
1247 | } | |
1248 | called = 1; | |
1249 | debug("packet_set_maxsize: setting to %d", s); | |
1250 | max_packet_size = s; | |
1251 | return s; | |
1252 | } | |
1253 | ||
1254 | /* roundup current message to pad bytes */ | |
1255 | void | |
1256 | packet_add_padding(u_char pad) | |
1257 | { | |
1258 | extra_pad = pad; | |
1259 | } | |
1260 | ||
1261 | /* | |
1262 | * 9.2. Ignored Data Message | |
1263 | * | |
1264 | * byte SSH_MSG_IGNORE | |
1265 | * string data | |
1266 | * | |
1267 | * All implementations MUST understand (and ignore) this message at any | |
1268 | * time (after receiving the protocol version). No implementation is | |
1269 | * required to send them. This message can be used as an additional | |
1270 | * protection measure against advanced traffic analysis techniques. | |
1271 | */ | |
1272 | void | |
1273 | packet_send_ignore(int nbytes) | |
1274 | { | |
1275 | u_int32_t rand = 0; | |
1276 | int i; | |
1277 | ||
1278 | packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); | |
1279 | packet_put_int(nbytes); | |
1280 | for(i = 0; i < nbytes; i++) { | |
1281 | if (i % 4 == 0) | |
1282 | rand = arc4random(); | |
1283 | packet_put_char(rand & 0xff); | |
1284 | rand >>= 8; | |
1285 | } | |
1286 | } |