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Commit | Line | Data |
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8efc0c15 | 1 | /* |
5260325f | 2 | * |
3 | * packet.c | |
4 | * | |
5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | * | |
7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | * All rights reserved | |
9 | * | |
10 | * Created: Sat Mar 18 02:40:40 1995 ylo | |
11 | * | |
12 | * This file contains code implementing the packet protocol and communication | |
13 | * with the other side. This same code is used both on client and server side. | |
14 | * | |
15 | */ | |
8efc0c15 | 16 | |
17 | #include "includes.h" | |
18 | RCSID("$Id$"); | |
19 | ||
20 | #include "xmalloc.h" | |
21 | #include "buffer.h" | |
22 | #include "packet.h" | |
23 | #include "bufaux.h" | |
24 | #include "ssh.h" | |
25 | #include "crc32.h" | |
26 | #include "cipher.h" | |
27 | #include "getput.h" | |
28 | ||
29 | #include "compress.h" | |
30 | #include "deattack.h" | |
31 | ||
aa3378df | 32 | /* |
33 | * This variable contains the file descriptors used for communicating with | |
34 | * the other side. connection_in is used for reading; connection_out for | |
35 | * writing. These can be the same descriptor, in which case it is assumed to | |
36 | * be a socket. | |
37 | */ | |
8efc0c15 | 38 | static int connection_in = -1; |
39 | static int connection_out = -1; | |
40 | ||
aa3378df | 41 | /* |
42 | * Cipher type. This value is only used to determine whether to pad the | |
43 | * packets with zeroes or random data. | |
44 | */ | |
8efc0c15 | 45 | static int cipher_type = SSH_CIPHER_NONE; |
46 | ||
47 | /* Protocol flags for the remote side. */ | |
48 | static unsigned int remote_protocol_flags = 0; | |
49 | ||
50 | /* Encryption context for receiving data. This is only used for decryption. */ | |
51 | static CipherContext receive_context; | |
5260325f | 52 | |
53 | /* Encryption context for sending data. This is only used for encryption. */ | |
8efc0c15 | 54 | static CipherContext send_context; |
55 | ||
56 | /* Buffer for raw input data from the socket. */ | |
57 | static Buffer input; | |
58 | ||
59 | /* Buffer for raw output data going to the socket. */ | |
60 | static Buffer output; | |
61 | ||
62 | /* Buffer for the partial outgoing packet being constructed. */ | |
63 | static Buffer outgoing_packet; | |
64 | ||
65 | /* Buffer for the incoming packet currently being processed. */ | |
66 | static Buffer incoming_packet; | |
67 | ||
68 | /* Scratch buffer for packet compression/decompression. */ | |
69 | static Buffer compression_buffer; | |
70 | ||
71 | /* Flag indicating whether packet compression/decompression is enabled. */ | |
72 | static int packet_compression = 0; | |
73 | ||
9d6b7add | 74 | /* default maximum packet size */ |
75 | int max_packet_size = 32768; | |
76 | ||
8efc0c15 | 77 | /* Flag indicating whether this module has been initialized. */ |
78 | static int initialized = 0; | |
79 | ||
80 | /* Set to true if the connection is interactive. */ | |
81 | static int interactive_mode = 0; | |
82 | ||
aa3378df | 83 | /* |
84 | * Sets the descriptors used for communication. Disables encryption until | |
85 | * packet_set_encryption_key is called. | |
86 | */ | |
8efc0c15 | 87 | |
88 | void | |
89 | packet_set_connection(int fd_in, int fd_out) | |
90 | { | |
5260325f | 91 | connection_in = fd_in; |
92 | connection_out = fd_out; | |
93 | cipher_type = SSH_CIPHER_NONE; | |
94 | cipher_set_key(&send_context, SSH_CIPHER_NONE, (unsigned char *) "", 0, 1); | |
95 | cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *) "", 0, 0); | |
96 | if (!initialized) { | |
97 | initialized = 1; | |
98 | buffer_init(&input); | |
99 | buffer_init(&output); | |
100 | buffer_init(&outgoing_packet); | |
101 | buffer_init(&incoming_packet); | |
102 | } | |
103 | /* Kludge: arrange the close function to be called from fatal(). */ | |
104 | fatal_add_cleanup((void (*) (void *)) packet_close, NULL); | |
8efc0c15 | 105 | } |
106 | ||
107 | /* Sets the connection into non-blocking mode. */ | |
108 | ||
109 | void | |
110 | packet_set_nonblocking() | |
111 | { | |
5260325f | 112 | /* Set the socket into non-blocking mode. */ |
113 | if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) | |
114 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
8efc0c15 | 115 | |
5260325f | 116 | if (connection_out != connection_in) { |
117 | if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) | |
118 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); | |
119 | } | |
8efc0c15 | 120 | } |
121 | ||
122 | /* Returns the socket used for reading. */ | |
123 | ||
124 | int | |
125 | packet_get_connection_in() | |
126 | { | |
5260325f | 127 | return connection_in; |
8efc0c15 | 128 | } |
129 | ||
130 | /* Returns the descriptor used for writing. */ | |
131 | ||
132 | int | |
133 | packet_get_connection_out() | |
134 | { | |
5260325f | 135 | return connection_out; |
8efc0c15 | 136 | } |
137 | ||
138 | /* Closes the connection and clears and frees internal data structures. */ | |
139 | ||
140 | void | |
141 | packet_close() | |
142 | { | |
5260325f | 143 | if (!initialized) |
144 | return; | |
145 | initialized = 0; | |
146 | if (connection_in == connection_out) { | |
147 | shutdown(connection_out, SHUT_RDWR); | |
148 | close(connection_out); | |
149 | } else { | |
150 | close(connection_in); | |
151 | close(connection_out); | |
152 | } | |
153 | buffer_free(&input); | |
154 | buffer_free(&output); | |
155 | buffer_free(&outgoing_packet); | |
156 | buffer_free(&incoming_packet); | |
157 | if (packet_compression) { | |
158 | buffer_free(&compression_buffer); | |
159 | buffer_compress_uninit(); | |
160 | } | |
8efc0c15 | 161 | } |
162 | ||
163 | /* Sets remote side protocol flags. */ | |
164 | ||
165 | void | |
166 | packet_set_protocol_flags(unsigned int protocol_flags) | |
167 | { | |
5260325f | 168 | remote_protocol_flags = protocol_flags; |
169 | channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0); | |
8efc0c15 | 170 | } |
171 | ||
172 | /* Returns the remote protocol flags set earlier by the above function. */ | |
173 | ||
174 | unsigned int | |
175 | packet_get_protocol_flags() | |
176 | { | |
5260325f | 177 | return remote_protocol_flags; |
8efc0c15 | 178 | } |
179 | ||
aa3378df | 180 | /* |
181 | * Starts packet compression from the next packet on in both directions. | |
182 | * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. | |
183 | */ | |
8efc0c15 | 184 | |
185 | void | |
186 | packet_start_compression(int level) | |
187 | { | |
5260325f | 188 | if (packet_compression) |
189 | fatal("Compression already enabled."); | |
190 | packet_compression = 1; | |
191 | buffer_init(&compression_buffer); | |
192 | buffer_compress_init(level); | |
8efc0c15 | 193 | } |
194 | ||
aa3378df | 195 | /* |
196 | * Encrypts the given number of bytes, copying from src to dest. bytes is | |
197 | * known to be a multiple of 8. | |
198 | */ | |
8efc0c15 | 199 | |
200 | void | |
5260325f | 201 | packet_encrypt(CipherContext * cc, void *dest, void *src, |
8efc0c15 | 202 | unsigned int bytes) |
203 | { | |
5260325f | 204 | cipher_encrypt(cc, dest, src, bytes); |
8efc0c15 | 205 | } |
206 | ||
aa3378df | 207 | /* |
208 | * Decrypts the given number of bytes, copying from src to dest. bytes is | |
209 | * known to be a multiple of 8. | |
210 | */ | |
8efc0c15 | 211 | |
212 | void | |
5260325f | 213 | packet_decrypt(CipherContext * cc, void *dest, void *src, |
8efc0c15 | 214 | unsigned int bytes) |
215 | { | |
5260325f | 216 | int i; |
217 | ||
218 | if ((bytes % 8) != 0) | |
219 | fatal("packet_decrypt: bad ciphertext length %d", bytes); | |
220 | ||
aa3378df | 221 | /* |
222 | * Cryptographic attack detector for ssh - Modifications for packet.c | |
223 | * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com) | |
224 | */ | |
5260325f | 225 | |
226 | switch (cc->type) { | |
227 | case SSH_CIPHER_NONE: | |
228 | i = DEATTACK_OK; | |
229 | break; | |
230 | default: | |
231 | i = detect_attack(src, bytes, NULL); | |
232 | break; | |
233 | } | |
234 | ||
235 | if (i == DEATTACK_DETECTED) | |
236 | packet_disconnect("crc32 compensation attack: network attack detected"); | |
237 | ||
238 | cipher_decrypt(cc, dest, src, bytes); | |
8efc0c15 | 239 | } |
240 | ||
aa3378df | 241 | /* |
242 | * Causes any further packets to be encrypted using the given key. The same | |
243 | * key is used for both sending and reception. However, both directions are | |
244 | * encrypted independently of each other. | |
245 | */ | |
8efc0c15 | 246 | |
247 | void | |
248 | packet_set_encryption_key(const unsigned char *key, unsigned int keylen, | |
4d195447 | 249 | int cipher) |
8efc0c15 | 250 | { |
5260325f | 251 | /* All other ciphers use the same key in both directions for now. */ |
252 | cipher_set_key(&receive_context, cipher, key, keylen, 0); | |
253 | cipher_set_key(&send_context, cipher, key, keylen, 1); | |
8efc0c15 | 254 | } |
255 | ||
256 | /* Starts constructing a packet to send. */ | |
257 | ||
258 | void | |
259 | packet_start(int type) | |
260 | { | |
5260325f | 261 | char buf[9]; |
8efc0c15 | 262 | |
5260325f | 263 | buffer_clear(&outgoing_packet); |
264 | memset(buf, 0, 8); | |
265 | buf[8] = type; | |
266 | buffer_append(&outgoing_packet, buf, 9); | |
8efc0c15 | 267 | } |
268 | ||
269 | /* Appends a character to the packet data. */ | |
270 | ||
271 | void | |
272 | packet_put_char(int value) | |
273 | { | |
5260325f | 274 | char ch = value; |
275 | buffer_append(&outgoing_packet, &ch, 1); | |
8efc0c15 | 276 | } |
277 | ||
278 | /* Appends an integer to the packet data. */ | |
279 | ||
280 | void | |
281 | packet_put_int(unsigned int value) | |
282 | { | |
5260325f | 283 | buffer_put_int(&outgoing_packet, value); |
8efc0c15 | 284 | } |
285 | ||
286 | /* Appends a string to packet data. */ | |
287 | ||
288 | void | |
289 | packet_put_string(const char *buf, unsigned int len) | |
290 | { | |
5260325f | 291 | buffer_put_string(&outgoing_packet, buf, len); |
8efc0c15 | 292 | } |
293 | ||
294 | /* Appends an arbitrary precision integer to packet data. */ | |
295 | ||
296 | void | |
5260325f | 297 | packet_put_bignum(BIGNUM * value) |
8efc0c15 | 298 | { |
5260325f | 299 | buffer_put_bignum(&outgoing_packet, value); |
8efc0c15 | 300 | } |
301 | ||
aa3378df | 302 | /* |
303 | * Finalizes and sends the packet. If the encryption key has been set, | |
304 | * encrypts the packet before sending. | |
305 | */ | |
5260325f | 306 | |
8efc0c15 | 307 | void |
308 | packet_send() | |
309 | { | |
5260325f | 310 | char buf[8], *cp; |
311 | int i, padding, len; | |
312 | unsigned int checksum; | |
313 | u_int32_t rand = 0; | |
314 | ||
aa3378df | 315 | /* |
316 | * If using packet compression, compress the payload of the outgoing | |
317 | * packet. | |
318 | */ | |
5260325f | 319 | if (packet_compression) { |
320 | buffer_clear(&compression_buffer); | |
321 | /* Skip padding. */ | |
322 | buffer_consume(&outgoing_packet, 8); | |
323 | /* padding */ | |
324 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); | |
325 | buffer_compress(&outgoing_packet, &compression_buffer); | |
326 | buffer_clear(&outgoing_packet); | |
327 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), | |
328 | buffer_len(&compression_buffer)); | |
329 | } | |
330 | /* Compute packet length without padding (add checksum, remove padding). */ | |
331 | len = buffer_len(&outgoing_packet) + 4 - 8; | |
332 | ||
333 | /* Insert padding. */ | |
334 | padding = 8 - len % 8; | |
335 | if (cipher_type != SSH_CIPHER_NONE) { | |
336 | cp = buffer_ptr(&outgoing_packet); | |
337 | for (i = 0; i < padding; i++) { | |
338 | if (i % 4 == 0) | |
339 | rand = arc4random(); | |
340 | cp[7 - i] = rand & 0xff; | |
341 | rand >>= 8; | |
342 | } | |
343 | } | |
344 | buffer_consume(&outgoing_packet, 8 - padding); | |
345 | ||
346 | /* Add check bytes. */ | |
347 | checksum = crc32((unsigned char *) buffer_ptr(&outgoing_packet), | |
348 | buffer_len(&outgoing_packet)); | |
349 | PUT_32BIT(buf, checksum); | |
350 | buffer_append(&outgoing_packet, buf, 4); | |
8efc0c15 | 351 | |
352 | #ifdef PACKET_DEBUG | |
5260325f | 353 | fprintf(stderr, "packet_send plain: "); |
354 | buffer_dump(&outgoing_packet); | |
8efc0c15 | 355 | #endif |
356 | ||
5260325f | 357 | /* Append to output. */ |
358 | PUT_32BIT(buf, len); | |
359 | buffer_append(&output, buf, 4); | |
360 | buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); | |
361 | packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), | |
362 | buffer_len(&outgoing_packet)); | |
363 | ||
8efc0c15 | 364 | #ifdef PACKET_DEBUG |
5260325f | 365 | fprintf(stderr, "encrypted: "); |
366 | buffer_dump(&output); | |
8efc0c15 | 367 | #endif |
368 | ||
5260325f | 369 | buffer_clear(&outgoing_packet); |
8efc0c15 | 370 | |
aa3378df | 371 | /* |
372 | * Note that the packet is now only buffered in output. It won\'t be | |
373 | * actually sent until packet_write_wait or packet_write_poll is | |
374 | * called. | |
375 | */ | |
8efc0c15 | 376 | } |
377 | ||
aa3378df | 378 | /* |
379 | * Waits until a packet has been received, and returns its type. Note that | |
380 | * no other data is processed until this returns, so this function should not | |
381 | * be used during the interactive session. | |
382 | */ | |
8efc0c15 | 383 | |
384 | int | |
385 | packet_read(int *payload_len_ptr) | |
386 | { | |
5260325f | 387 | int type, len; |
388 | fd_set set; | |
389 | char buf[8192]; | |
390 | ||
391 | /* Since we are blocking, ensure that all written packets have been sent. */ | |
392 | packet_write_wait(); | |
393 | ||
394 | /* Stay in the loop until we have received a complete packet. */ | |
395 | for (;;) { | |
396 | /* Try to read a packet from the buffer. */ | |
397 | type = packet_read_poll(payload_len_ptr); | |
398 | if (type == SSH_SMSG_SUCCESS | |
399 | || type == SSH_SMSG_FAILURE | |
400 | || type == SSH_CMSG_EOF | |
401 | || type == SSH_CMSG_EXIT_CONFIRMATION) | |
402 | packet_integrity_check(*payload_len_ptr, 0, type); | |
403 | /* If we got a packet, return it. */ | |
404 | if (type != SSH_MSG_NONE) | |
405 | return type; | |
aa3378df | 406 | /* |
407 | * Otherwise, wait for some data to arrive, add it to the | |
408 | * buffer, and try again. | |
409 | */ | |
5260325f | 410 | FD_ZERO(&set); |
411 | FD_SET(connection_in, &set); | |
aa3378df | 412 | |
5260325f | 413 | /* Wait for some data to arrive. */ |
414 | select(connection_in + 1, &set, NULL, NULL, NULL); | |
aa3378df | 415 | |
5260325f | 416 | /* Read data from the socket. */ |
417 | len = read(connection_in, buf, sizeof(buf)); | |
418 | if (len == 0) | |
419 | fatal("Connection closed by %.200s", get_remote_ipaddr()); | |
420 | if (len < 0) | |
421 | fatal("Read from socket failed: %.100s", strerror(errno)); | |
422 | /* Append it to the buffer. */ | |
423 | packet_process_incoming(buf, len); | |
424 | } | |
425 | /* NOTREACHED */ | |
8efc0c15 | 426 | } |
427 | ||
aa3378df | 428 | /* |
429 | * Waits until a packet has been received, verifies that its type matches | |
430 | * that given, and gives a fatal error and exits if there is a mismatch. | |
431 | */ | |
8efc0c15 | 432 | |
433 | void | |
434 | packet_read_expect(int *payload_len_ptr, int expected_type) | |
435 | { | |
5260325f | 436 | int type; |
8efc0c15 | 437 | |
5260325f | 438 | type = packet_read(payload_len_ptr); |
439 | if (type != expected_type) | |
440 | packet_disconnect("Protocol error: expected packet type %d, got %d", | |
441 | expected_type, type); | |
8efc0c15 | 442 | } |
443 | ||
444 | /* Checks if a full packet is available in the data received so far via | |
5260325f | 445 | * packet_process_incoming. If so, reads the packet; otherwise returns |
446 | * SSH_MSG_NONE. This does not wait for data from the connection. | |
447 | * | |
448 | * SSH_MSG_DISCONNECT is handled specially here. Also, | |
449 | * SSH_MSG_IGNORE messages are skipped by this function and are never returned | |
450 | * to higher levels. | |
451 | * | |
452 | * The returned payload_len does include space consumed by: | |
453 | * Packet length | |
454 | * Padding | |
455 | * Packet type | |
456 | * Check bytes | |
457 | */ | |
8efc0c15 | 458 | |
459 | int | |
460 | packet_read_poll(int *payload_len_ptr) | |
461 | { | |
5260325f | 462 | unsigned int len, padded_len; |
463 | unsigned char *ucp; | |
464 | char buf[8], *cp; | |
465 | unsigned int checksum, stored_checksum; | |
466 | ||
467 | restart: | |
468 | ||
469 | /* Check if input size is less than minimum packet size. */ | |
470 | if (buffer_len(&input) < 4 + 8) | |
471 | return SSH_MSG_NONE; | |
472 | /* Get length of incoming packet. */ | |
473 | ucp = (unsigned char *) buffer_ptr(&input); | |
474 | len = GET_32BIT(ucp); | |
475 | if (len < 1 + 2 + 2 || len > 256 * 1024) | |
476 | packet_disconnect("Bad packet length %d.", len); | |
477 | padded_len = (len + 8) & ~7; | |
478 | ||
479 | /* Check if the packet has been entirely received. */ | |
480 | if (buffer_len(&input) < 4 + padded_len) | |
481 | return SSH_MSG_NONE; | |
482 | ||
483 | /* The entire packet is in buffer. */ | |
484 | ||
485 | /* Consume packet length. */ | |
486 | buffer_consume(&input, 4); | |
487 | ||
488 | /* Copy data to incoming_packet. */ | |
489 | buffer_clear(&incoming_packet); | |
490 | buffer_append_space(&incoming_packet, &cp, padded_len); | |
491 | packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); | |
492 | buffer_consume(&input, padded_len); | |
8efc0c15 | 493 | |
494 | #ifdef PACKET_DEBUG | |
5260325f | 495 | fprintf(stderr, "read_poll plain: "); |
496 | buffer_dump(&incoming_packet); | |
8efc0c15 | 497 | #endif |
5260325f | 498 | |
499 | /* Compute packet checksum. */ | |
500 | checksum = crc32((unsigned char *) buffer_ptr(&incoming_packet), | |
501 | buffer_len(&incoming_packet) - 4); | |
502 | ||
503 | /* Skip padding. */ | |
504 | buffer_consume(&incoming_packet, 8 - len % 8); | |
505 | ||
506 | /* Test check bytes. */ | |
507 | ||
508 | if (len != buffer_len(&incoming_packet)) | |
509 | packet_disconnect("packet_read_poll: len %d != buffer_len %d.", | |
510 | len, buffer_len(&incoming_packet)); | |
511 | ||
512 | ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4; | |
513 | stored_checksum = GET_32BIT(ucp); | |
514 | if (checksum != stored_checksum) | |
515 | packet_disconnect("Corrupted check bytes on input."); | |
516 | buffer_consume_end(&incoming_packet, 4); | |
517 | ||
518 | /* If using packet compression, decompress the packet. */ | |
519 | if (packet_compression) { | |
520 | buffer_clear(&compression_buffer); | |
521 | buffer_uncompress(&incoming_packet, &compression_buffer); | |
522 | buffer_clear(&incoming_packet); | |
523 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), | |
524 | buffer_len(&compression_buffer)); | |
525 | } | |
526 | /* Get packet type. */ | |
527 | buffer_get(&incoming_packet, &buf[0], 1); | |
528 | ||
529 | /* Return length of payload (without type field). */ | |
530 | *payload_len_ptr = buffer_len(&incoming_packet); | |
531 | ||
532 | /* Handle disconnect message. */ | |
533 | if ((unsigned char) buf[0] == SSH_MSG_DISCONNECT) | |
534 | fatal("Received disconnect: %.900s", packet_get_string(NULL)); | |
535 | ||
536 | /* Ignore ignore messages. */ | |
537 | if ((unsigned char) buf[0] == SSH_MSG_IGNORE) | |
538 | goto restart; | |
539 | ||
540 | /* Send debug messages as debugging output. */ | |
541 | if ((unsigned char) buf[0] == SSH_MSG_DEBUG) { | |
542 | debug("Remote: %.900s", packet_get_string(NULL)); | |
543 | goto restart; | |
544 | } | |
545 | /* Return type. */ | |
546 | return (unsigned char) buf[0]; | |
547 | } | |
548 | ||
aa3378df | 549 | /* |
550 | * Buffers the given amount of input characters. This is intended to be used | |
551 | * together with packet_read_poll. | |
552 | */ | |
8efc0c15 | 553 | |
554 | void | |
555 | packet_process_incoming(const char *buf, unsigned int len) | |
556 | { | |
5260325f | 557 | buffer_append(&input, buf, len); |
8efc0c15 | 558 | } |
559 | ||
560 | /* Returns a character from the packet. */ | |
561 | ||
562 | unsigned int | |
563 | packet_get_char() | |
564 | { | |
5260325f | 565 | char ch; |
566 | buffer_get(&incoming_packet, &ch, 1); | |
567 | return (unsigned char) ch; | |
8efc0c15 | 568 | } |
569 | ||
570 | /* Returns an integer from the packet data. */ | |
571 | ||
572 | unsigned int | |
573 | packet_get_int() | |
574 | { | |
5260325f | 575 | return buffer_get_int(&incoming_packet); |
8efc0c15 | 576 | } |
577 | ||
aa3378df | 578 | /* |
579 | * Returns an arbitrary precision integer from the packet data. The integer | |
580 | * must have been initialized before this call. | |
581 | */ | |
8efc0c15 | 582 | |
583 | void | |
5260325f | 584 | packet_get_bignum(BIGNUM * value, int *length_ptr) |
8efc0c15 | 585 | { |
5260325f | 586 | *length_ptr = buffer_get_bignum(&incoming_packet, value); |
8efc0c15 | 587 | } |
588 | ||
aa3378df | 589 | /* |
590 | * Returns a string from the packet data. The string is allocated using | |
591 | * xmalloc; it is the responsibility of the calling program to free it when | |
592 | * no longer needed. The length_ptr argument may be NULL, or point to an | |
593 | * integer into which the length of the string is stored. | |
594 | */ | |
8efc0c15 | 595 | |
aa3378df | 596 | char * |
5260325f | 597 | packet_get_string(unsigned int *length_ptr) |
8efc0c15 | 598 | { |
5260325f | 599 | return buffer_get_string(&incoming_packet, length_ptr); |
8efc0c15 | 600 | } |
601 | ||
aa3378df | 602 | /* |
603 | * Sends a diagnostic message from the server to the client. This message | |
604 | * can be sent at any time (but not while constructing another message). The | |
605 | * message is printed immediately, but only if the client is being executed | |
606 | * in verbose mode. These messages are primarily intended to ease debugging | |
607 | * authentication problems. The length of the formatted message must not | |
608 | * exceed 1024 bytes. This will automatically call packet_write_wait. | |
609 | */ | |
8efc0c15 | 610 | |
611 | void | |
5260325f | 612 | packet_send_debug(const char *fmt,...) |
8efc0c15 | 613 | { |
5260325f | 614 | char buf[1024]; |
615 | va_list args; | |
616 | ||
617 | va_start(args, fmt); | |
618 | vsnprintf(buf, sizeof(buf), fmt, args); | |
619 | va_end(args); | |
620 | ||
621 | packet_start(SSH_MSG_DEBUG); | |
622 | packet_put_string(buf, strlen(buf)); | |
623 | packet_send(); | |
624 | packet_write_wait(); | |
8efc0c15 | 625 | } |
626 | ||
aa3378df | 627 | /* |
628 | * Logs the error plus constructs and sends a disconnect packet, closes the | |
629 | * connection, and exits. This function never returns. The error message | |
630 | * should not contain a newline. The length of the formatted message must | |
631 | * not exceed 1024 bytes. | |
632 | */ | |
8efc0c15 | 633 | |
634 | void | |
5260325f | 635 | packet_disconnect(const char *fmt,...) |
636 | { | |
637 | char buf[1024]; | |
638 | va_list args; | |
639 | static int disconnecting = 0; | |
640 | if (disconnecting) /* Guard against recursive invocations. */ | |
641 | fatal("packet_disconnect called recursively."); | |
642 | disconnecting = 1; | |
643 | ||
aa3378df | 644 | /* |
645 | * Format the message. Note that the caller must make sure the | |
646 | * message is of limited size. | |
647 | */ | |
5260325f | 648 | va_start(args, fmt); |
649 | vsnprintf(buf, sizeof(buf), fmt, args); | |
650 | va_end(args); | |
651 | ||
652 | /* Send the disconnect message to the other side, and wait for it to get sent. */ | |
653 | packet_start(SSH_MSG_DISCONNECT); | |
654 | packet_put_string(buf, strlen(buf)); | |
655 | packet_send(); | |
656 | packet_write_wait(); | |
657 | ||
658 | /* Stop listening for connections. */ | |
659 | channel_stop_listening(); | |
660 | ||
661 | /* Close the connection. */ | |
662 | packet_close(); | |
663 | ||
664 | /* Display the error locally and exit. */ | |
665 | fatal("Disconnecting: %.100s", buf); | |
8efc0c15 | 666 | } |
667 | ||
aa3378df | 668 | /* Checks if there is any buffered output, and tries to write some of the output. */ |
8efc0c15 | 669 | |
670 | void | |
671 | packet_write_poll() | |
672 | { | |
5260325f | 673 | int len = buffer_len(&output); |
674 | if (len > 0) { | |
675 | len = write(connection_out, buffer_ptr(&output), len); | |
676 | if (len <= 0) { | |
677 | if (errno == EAGAIN) | |
678 | return; | |
679 | else | |
680 | fatal("Write failed: %.100s", strerror(errno)); | |
681 | } | |
682 | buffer_consume(&output, len); | |
683 | } | |
8efc0c15 | 684 | } |
685 | ||
aa3378df | 686 | /* |
687 | * Calls packet_write_poll repeatedly until all pending output data has been | |
688 | * written. | |
689 | */ | |
8efc0c15 | 690 | |
691 | void | |
692 | packet_write_wait() | |
693 | { | |
5260325f | 694 | packet_write_poll(); |
695 | while (packet_have_data_to_write()) { | |
696 | fd_set set; | |
697 | FD_ZERO(&set); | |
698 | FD_SET(connection_out, &set); | |
699 | select(connection_out + 1, NULL, &set, NULL, NULL); | |
700 | packet_write_poll(); | |
701 | } | |
8efc0c15 | 702 | } |
703 | ||
704 | /* Returns true if there is buffered data to write to the connection. */ | |
705 | ||
706 | int | |
707 | packet_have_data_to_write() | |
708 | { | |
5260325f | 709 | return buffer_len(&output) != 0; |
8efc0c15 | 710 | } |
711 | ||
712 | /* Returns true if there is not too much data to write to the connection. */ | |
713 | ||
714 | int | |
715 | packet_not_very_much_data_to_write() | |
716 | { | |
5260325f | 717 | if (interactive_mode) |
718 | return buffer_len(&output) < 16384; | |
719 | else | |
720 | return buffer_len(&output) < 128 * 1024; | |
8efc0c15 | 721 | } |
722 | ||
723 | /* Informs that the current session is interactive. Sets IP flags for that. */ | |
724 | ||
725 | void | |
726 | packet_set_interactive(int interactive, int keepalives) | |
727 | { | |
5260325f | 728 | int on = 1; |
729 | ||
730 | /* Record that we are in interactive mode. */ | |
731 | interactive_mode = interactive; | |
732 | ||
aa3378df | 733 | /* |
734 | * Only set socket options if using a socket (as indicated by the | |
735 | * descriptors being the same). | |
736 | */ | |
5260325f | 737 | if (connection_in != connection_out) |
738 | return; | |
739 | ||
740 | if (keepalives) { | |
741 | /* Set keepalives if requested. */ | |
742 | if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *) &on, | |
743 | sizeof(on)) < 0) | |
744 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
745 | } | |
746 | if (interactive) { | |
aa3378df | 747 | /* |
748 | * Set IP options for an interactive connection. Use | |
749 | * IPTOS_LOWDELAY and TCP_NODELAY. | |
750 | */ | |
5260325f | 751 | int lowdelay = IPTOS_LOWDELAY; |
752 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &lowdelay, | |
753 | sizeof(lowdelay)) < 0) | |
754 | error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno)); | |
755 | if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, | |
756 | sizeof(on)) < 0) | |
757 | error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); | |
758 | } else { | |
aa3378df | 759 | /* |
760 | * Set IP options for a non-interactive connection. Use | |
761 | * IPTOS_THROUGHPUT. | |
762 | */ | |
5260325f | 763 | int throughput = IPTOS_THROUGHPUT; |
764 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput, | |
765 | sizeof(throughput)) < 0) | |
766 | error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); | |
767 | } | |
8efc0c15 | 768 | } |
769 | ||
770 | /* Returns true if the current connection is interactive. */ | |
771 | ||
772 | int | |
773 | packet_is_interactive() | |
774 | { | |
5260325f | 775 | return interactive_mode; |
8efc0c15 | 776 | } |
9d6b7add | 777 | |
778 | int | |
779 | packet_set_maxsize(int s) | |
780 | { | |
5260325f | 781 | static int called = 0; |
782 | if (called) { | |
783 | log("packet_set_maxsize: called twice: old %d new %d", max_packet_size, s); | |
784 | return -1; | |
785 | } | |
786 | if (s < 4 * 1024 || s > 1024 * 1024) { | |
787 | log("packet_set_maxsize: bad size %d", s); | |
788 | return -1; | |
789 | } | |
790 | log("packet_set_maxsize: setting to %d", s); | |
791 | max_packet_size = s; | |
792 | return s; | |
9d6b7add | 793 | } |