Annotation of src/usr.bin/ssh/packet.c, Revision 1.66
1.1 deraadt 1: /*
1.15 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
1.35 deraadt 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.
1.29 markus 7: *
1.35 deraadt 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".
1.29 markus 13: *
1.25 markus 14: *
15: * SSH2 packet format added by Markus Friedl.
1.35 deraadt 16: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.25 markus 17: *
1.35 deraadt 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.
1.15 deraadt 37: */
1.1 deraadt 38:
39: #include "includes.h"
1.66 ! markus 40: RCSID("$OpenBSD: packet.c,v 1.65 2001/06/07 20:23:04 markus Exp $");
1.1 deraadt 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"
1.9 dugsong 50: #include "deattack.h"
1.64 markus 51: #include "channels.h"
1.1 deraadt 52:
1.25 markus 53: #include "compat.h"
1.45 markus 54: #include "ssh1.h"
1.25 markus 55: #include "ssh2.h"
56:
1.37 markus 57: #include "cipher.h"
1.25 markus 58: #include "kex.h"
1.50 markus 59: #include "mac.h"
1.46 markus 60: #include "log.h"
61: #include "canohost.h"
1.25 markus 62:
63: #ifdef PACKET_DEBUG
64: #define DBG(x) x
65: #else
66: #define DBG(x)
67: #endif
68:
1.16 markus 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: */
1.1 deraadt 75: static int connection_in = -1;
76: static int connection_out = -1;
77:
78: /* Protocol flags for the remote side. */
1.40 markus 79: static u_int remote_protocol_flags = 0;
1.1 deraadt 80:
81: /* Encryption context for receiving data. This is only used for decryption. */
82: static CipherContext receive_context;
1.14 markus 83:
84: /* Encryption context for sending data. This is only used for encryption. */
1.1 deraadt 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;
1.60 markus 101: static int compression_buffer_ready = 0;
1.1 deraadt 102:
103: /* Flag indicating whether packet compression/decompression is enabled. */
104: static int packet_compression = 0;
105:
1.12 markus 106: /* default maximum packet size */
107: int max_packet_size = 32768;
108:
1.1 deraadt 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:
1.25 markus 115: /* Session key information for Encryption and MAC */
1.57 markus 116: Newkeys *newkeys[MODE_MAX];
1.25 markus 117:
1.16 markus 118: /*
119: * Sets the descriptors used for communication. Disables encryption until
120: * packet_set_encryption_key is called.
121: */
1.2 provos 122: void
123: packet_set_connection(int fd_in, int fd_out)
1.1 deraadt 124: {
1.37 markus 125: Cipher *none = cipher_by_name("none");
126: if (none == NULL)
127: fatal("packet_set_connection: cannot load cipher 'none'");
1.14 markus 128: connection_in = fd_in;
129: connection_out = fd_out;
1.40 markus 130: cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0);
131: cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0);
1.62 markus 132: newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
1.14 markus 133: if (!initialized) {
134: initialized = 1;
135: buffer_init(&input);
136: buffer_init(&output);
137: buffer_init(&outgoing_packet);
138: buffer_init(&incoming_packet);
139: }
140: /* Kludge: arrange the close function to be called from fatal(). */
141: fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
1.1 deraadt 142: }
143:
1.19 markus 144: /* Returns 1 if remote host is connected via socket, 0 if not. */
145:
146: int
147: packet_connection_is_on_socket()
148: {
149: struct sockaddr_storage from, to;
150: socklen_t fromlen, tolen;
151:
152: /* filedescriptors in and out are the same, so it's a socket */
153: if (connection_in == connection_out)
154: return 1;
155: fromlen = sizeof(from);
156: memset(&from, 0, sizeof(from));
1.20 markus 157: if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
1.19 markus 158: return 0;
159: tolen = sizeof(to);
160: memset(&to, 0, sizeof(to));
1.20 markus 161: if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
1.19 markus 162: return 0;
163: if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
164: return 0;
165: if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
166: return 0;
167: return 1;
168: }
169:
170: /* returns 1 if connection is via ipv4 */
171:
172: int
173: packet_connection_is_ipv4()
174: {
175: struct sockaddr_storage to;
1.21 deraadt 176: socklen_t tolen = sizeof(to);
1.19 markus 177:
178: memset(&to, 0, sizeof(to));
179: if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
180: return 0;
181: if (to.ss_family != AF_INET)
182: return 0;
183: return 1;
184: }
185:
1.1 deraadt 186: /* Sets the connection into non-blocking mode. */
187:
1.2 provos 188: void
189: packet_set_nonblocking()
1.1 deraadt 190: {
1.14 markus 191: /* Set the socket into non-blocking mode. */
192: if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
193: error("fcntl O_NONBLOCK: %.100s", strerror(errno));
194:
195: if (connection_out != connection_in) {
196: if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
197: error("fcntl O_NONBLOCK: %.100s", strerror(errno));
198: }
1.1 deraadt 199: }
200:
201: /* Returns the socket used for reading. */
202:
1.2 provos 203: int
204: packet_get_connection_in()
1.1 deraadt 205: {
1.14 markus 206: return connection_in;
1.1 deraadt 207: }
208:
209: /* Returns the descriptor used for writing. */
210:
1.2 provos 211: int
212: packet_get_connection_out()
1.1 deraadt 213: {
1.14 markus 214: return connection_out;
1.1 deraadt 215: }
216:
217: /* Closes the connection and clears and frees internal data structures. */
218:
1.2 provos 219: void
220: packet_close()
1.1 deraadt 221: {
1.14 markus 222: if (!initialized)
223: return;
224: initialized = 0;
225: if (connection_in == connection_out) {
226: shutdown(connection_out, SHUT_RDWR);
227: close(connection_out);
228: } else {
229: close(connection_in);
230: close(connection_out);
231: }
232: buffer_free(&input);
233: buffer_free(&output);
234: buffer_free(&outgoing_packet);
235: buffer_free(&incoming_packet);
1.60 markus 236: if (compression_buffer_ready) {
1.14 markus 237: buffer_free(&compression_buffer);
238: buffer_compress_uninit();
239: }
1.1 deraadt 240: }
241:
242: /* Sets remote side protocol flags. */
243:
1.2 provos 244: void
1.40 markus 245: packet_set_protocol_flags(u_int protocol_flags)
1.1 deraadt 246: {
1.14 markus 247: remote_protocol_flags = protocol_flags;
1.1 deraadt 248: }
249:
250: /* Returns the remote protocol flags set earlier by the above function. */
251:
1.40 markus 252: u_int
1.2 provos 253: packet_get_protocol_flags()
1.1 deraadt 254: {
1.14 markus 255: return remote_protocol_flags;
1.1 deraadt 256: }
257:
1.16 markus 258: /*
259: * Starts packet compression from the next packet on in both directions.
260: * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
261: */
1.1 deraadt 262:
1.60 markus 263: void
264: packet_init_compression()
265: {
266: if (compression_buffer_ready == 1)
267: return;
268: compression_buffer_ready = 1;
269: buffer_init(&compression_buffer);
270: }
271:
1.2 provos 272: void
273: packet_start_compression(int level)
1.1 deraadt 274: {
1.62 markus 275: if (packet_compression && !compat20)
1.14 markus 276: fatal("Compression already enabled.");
277: packet_compression = 1;
1.60 markus 278: packet_init_compression();
279: buffer_compress_init_send(level);
280: buffer_compress_init_recv();
1.1 deraadt 281: }
282:
1.16 markus 283: /*
284: * Causes any further packets to be encrypted using the given key. The same
285: * key is used for both sending and reception. However, both directions are
286: * encrypted independently of each other.
287: */
1.2 provos 288: void
1.40 markus 289: packet_set_encryption_key(const u_char *key, u_int keylen,
1.37 markus 290: int number)
1.1 deraadt 291: {
1.37 markus 292: Cipher *cipher = cipher_by_number(number);
293: if (cipher == NULL)
294: fatal("packet_set_encryption_key: unknown cipher number %d", number);
1.25 markus 295: if (keylen < 20)
1.37 markus 296: fatal("packet_set_encryption_key: keylen too small: %d", keylen);
297: cipher_init(&receive_context, cipher, key, keylen, NULL, 0);
298: cipher_init(&send_context, cipher, key, keylen, NULL, 0);
1.1 deraadt 299: }
300:
1.62 markus 301: /* Start constructing a packet to send. */
1.2 provos 302: void
1.62 markus 303: packet_start(u_char type)
1.1 deraadt 304: {
1.62 markus 305: u_char buf[9];
306: int len;
1.1 deraadt 307:
1.62 markus 308: DBG(debug("packet_start[%d]", type));
309: len = compat20 ? 6 : 9;
310: memset(buf, 0, len - 1);
311: buf[len - 1] = type;
1.14 markus 312: buffer_clear(&outgoing_packet);
1.62 markus 313: buffer_append(&outgoing_packet, buf, len);
1.25 markus 314: }
315:
1.62 markus 316: /* Append payload. */
1.2 provos 317: void
318: packet_put_char(int value)
1.1 deraadt 319: {
1.14 markus 320: char ch = value;
321: buffer_append(&outgoing_packet, &ch, 1);
1.1 deraadt 322: }
1.2 provos 323: void
1.40 markus 324: packet_put_int(u_int value)
1.1 deraadt 325: {
1.14 markus 326: buffer_put_int(&outgoing_packet, value);
1.1 deraadt 327: }
1.2 provos 328: void
1.40 markus 329: packet_put_string(const char *buf, u_int len)
1.1 deraadt 330: {
1.14 markus 331: buffer_put_string(&outgoing_packet, buf, len);
1.1 deraadt 332: }
1.24 markus 333: void
334: packet_put_cstring(const char *str)
335: {
1.65 markus 336: buffer_put_cstring(&outgoing_packet, str);
1.24 markus 337: }
338: void
1.40 markus 339: packet_put_raw(const char *buf, u_int len)
1.24 markus 340: {
341: buffer_append(&outgoing_packet, buf, len);
342: }
1.2 provos 343: void
1.14 markus 344: packet_put_bignum(BIGNUM * value)
1.1 deraadt 345: {
1.14 markus 346: buffer_put_bignum(&outgoing_packet, value);
1.1 deraadt 347: }
1.24 markus 348: void
349: packet_put_bignum2(BIGNUM * value)
350: {
351: buffer_put_bignum2(&outgoing_packet, value);
352: }
1.1 deraadt 353:
1.16 markus 354: /*
355: * Finalizes and sends the packet. If the encryption key has been set,
356: * encrypts the packet before sending.
357: */
1.14 markus 358:
1.2 provos 359: void
1.49 itojun 360: packet_send1(void)
1.1 deraadt 361: {
1.14 markus 362: char buf[8], *cp;
363: int i, padding, len;
1.40 markus 364: u_int checksum;
1.14 markus 365: u_int32_t rand = 0;
366:
1.16 markus 367: /*
368: * If using packet compression, compress the payload of the outgoing
369: * packet.
370: */
1.14 markus 371: if (packet_compression) {
372: buffer_clear(&compression_buffer);
373: /* Skip padding. */
374: buffer_consume(&outgoing_packet, 8);
375: /* padding */
376: buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
377: buffer_compress(&outgoing_packet, &compression_buffer);
378: buffer_clear(&outgoing_packet);
379: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
380: buffer_len(&compression_buffer));
381: }
382: /* Compute packet length without padding (add checksum, remove padding). */
383: len = buffer_len(&outgoing_packet) + 4 - 8;
384:
1.32 markus 385: /* Insert padding. Initialized to zero in packet_start1() */
1.14 markus 386: padding = 8 - len % 8;
1.62 markus 387: if (send_context.cipher->number != SSH_CIPHER_NONE) {
1.14 markus 388: cp = buffer_ptr(&outgoing_packet);
389: for (i = 0; i < padding; i++) {
390: if (i % 4 == 0)
391: rand = arc4random();
392: cp[7 - i] = rand & 0xff;
393: rand >>= 8;
394: }
395: }
396: buffer_consume(&outgoing_packet, 8 - padding);
397:
398: /* Add check bytes. */
1.40 markus 399: checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet),
1.34 deraadt 400: buffer_len(&outgoing_packet));
1.14 markus 401: PUT_32BIT(buf, checksum);
402: buffer_append(&outgoing_packet, buf, 4);
1.1 deraadt 403:
404: #ifdef PACKET_DEBUG
1.14 markus 405: fprintf(stderr, "packet_send plain: ");
406: buffer_dump(&outgoing_packet);
1.1 deraadt 407: #endif
408:
1.14 markus 409: /* Append to output. */
410: PUT_32BIT(buf, len);
411: buffer_append(&output, buf, 4);
412: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
1.62 markus 413: cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
1.14 markus 414: buffer_len(&outgoing_packet));
415:
1.1 deraadt 416: #ifdef PACKET_DEBUG
1.14 markus 417: fprintf(stderr, "encrypted: ");
418: buffer_dump(&output);
1.1 deraadt 419: #endif
420:
1.14 markus 421: buffer_clear(&outgoing_packet);
1.1 deraadt 422:
1.16 markus 423: /*
424: * Note that the packet is now only buffered in output. It won\'t be
425: * actually sent until packet_write_wait or packet_write_poll is
426: * called.
427: */
1.1 deraadt 428: }
429:
1.57 markus 430: void
431: set_newkeys(int mode)
432: {
433: Enc *enc;
434: Mac *mac;
435: Comp *comp;
436: CipherContext *cc;
437:
438: debug("newkeys: mode %d", mode);
439:
440: cc = (mode == MODE_OUT) ? &send_context : &receive_context;
441: if (newkeys[mode] != NULL) {
442: debug("newkeys: rekeying");
1.59 markus 443: /* todo: free old keys, reset compression/cipher-ctxt; */
1.57 markus 444: memset(cc, 0, sizeof(*cc));
1.59 markus 445: enc = &newkeys[mode]->enc;
446: mac = &newkeys[mode]->mac;
447: comp = &newkeys[mode]->comp;
1.61 markus 448: memset(mac->key, 0, mac->key_len);
1.59 markus 449: xfree(enc->name);
450: xfree(enc->iv);
451: xfree(enc->key);
452: xfree(mac->name);
453: xfree(mac->key);
454: xfree(comp->name);
1.58 markus 455: xfree(newkeys[mode]);
1.57 markus 456: }
457: newkeys[mode] = kex_get_newkeys(mode);
458: if (newkeys[mode] == NULL)
459: fatal("newkeys: no keys for mode %d", mode);
460: enc = &newkeys[mode]->enc;
461: mac = &newkeys[mode]->mac;
462: comp = &newkeys[mode]->comp;
463: if (mac->md != NULL)
464: mac->enabled = 1;
465: DBG(debug("cipher_init_context: %d", mode));
466: cipher_init(cc, enc->cipher, enc->key, enc->cipher->key_len,
467: enc->iv, enc->cipher->block_size);
1.59 markus 468: memset(enc->iv, 0, enc->cipher->block_size);
469: memset(enc->key, 0, enc->cipher->key_len);
1.57 markus 470: if (comp->type != 0 && comp->enabled == 0) {
1.60 markus 471: packet_init_compression();
472: if (mode == MODE_OUT)
473: buffer_compress_init_send(6);
474: else
475: buffer_compress_init_recv();
1.57 markus 476: comp->enabled = 1;
477: }
478: }
479:
1.16 markus 480: /*
1.25 markus 481: * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
482: */
483: void
1.49 itojun 484: packet_send2(void)
1.25 markus 485: {
1.50 markus 486: static u_int32_t seqnr = 0;
1.62 markus 487: u_char type, *ucp, *macbuf = NULL;
1.25 markus 488: char *cp;
1.40 markus 489: u_int packet_length = 0;
490: u_int i, padlen, len;
1.25 markus 491: u_int32_t rand = 0;
492: Enc *enc = NULL;
493: Mac *mac = NULL;
494: Comp *comp = NULL;
495: int block_size;
496:
1.57 markus 497: if (newkeys[MODE_OUT] != NULL) {
498: enc = &newkeys[MODE_OUT]->enc;
499: mac = &newkeys[MODE_OUT]->mac;
500: comp = &newkeys[MODE_OUT]->comp;
1.25 markus 501: }
1.37 markus 502: block_size = enc ? enc->cipher->block_size : 8;
1.25 markus 503:
1.62 markus 504: ucp = (u_char *) buffer_ptr(&outgoing_packet);
505: type = ucp[5];
1.25 markus 506:
507: #ifdef PACKET_DEBUG
508: fprintf(stderr, "plain: ");
509: buffer_dump(&outgoing_packet);
510: #endif
511:
512: if (comp && comp->enabled) {
513: len = buffer_len(&outgoing_packet);
514: /* skip header, compress only payload */
515: buffer_consume(&outgoing_packet, 5);
516: buffer_clear(&compression_buffer);
517: buffer_compress(&outgoing_packet, &compression_buffer);
518: buffer_clear(&outgoing_packet);
519: buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
520: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
521: buffer_len(&compression_buffer));
522: DBG(debug("compression: raw %d compressed %d", len,
523: buffer_len(&outgoing_packet)));
524: }
525:
526: /* sizeof (packet_len + pad_len + payload) */
527: len = buffer_len(&outgoing_packet);
528:
529: /*
530: * calc size of padding, alloc space, get random data,
531: * minimum padding is 4 bytes
532: */
533: padlen = block_size - (len % block_size);
534: if (padlen < 4)
535: padlen += block_size;
536: buffer_append_space(&outgoing_packet, &cp, padlen);
1.38 markus 537: if (enc && enc->cipher->number != SSH_CIPHER_NONE) {
1.32 markus 538: /* random padding */
1.25 markus 539: for (i = 0; i < padlen; i++) {
540: if (i % 4 == 0)
541: rand = arc4random();
542: cp[i] = rand & 0xff;
1.52 markus 543: rand >>= 8;
1.25 markus 544: }
1.32 markus 545: } else {
546: /* clear padding */
547: memset(cp, 0, padlen);
1.25 markus 548: }
549: /* packet_length includes payload, padding and padding length field */
550: packet_length = buffer_len(&outgoing_packet) - 4;
1.62 markus 551: ucp = (u_char *)buffer_ptr(&outgoing_packet);
552: PUT_32BIT(ucp, packet_length);
553: ucp[4] = padlen;
1.25 markus 554: DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
555:
556: /* compute MAC over seqnr and packet(length fields, payload, padding) */
557: if (mac && mac->enabled) {
1.50 markus 558: macbuf = mac_compute(mac, seqnr,
1.40 markus 559: (u_char *) buffer_ptr(&outgoing_packet),
1.50 markus 560: buffer_len(&outgoing_packet));
1.36 markus 561: DBG(debug("done calc MAC out #%d", seqnr));
1.25 markus 562: }
563: /* encrypt packet and append to output buffer. */
564: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
1.62 markus 565: cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
1.25 markus 566: buffer_len(&outgoing_packet));
567: /* append unencrypted MAC */
568: if (mac && mac->enabled)
569: buffer_append(&output, (char *)macbuf, mac->mac_len);
570: #ifdef PACKET_DEBUG
571: fprintf(stderr, "encrypted: ");
572: buffer_dump(&output);
573: #endif
1.29 markus 574: /* increment sequence number for outgoing packets */
575: if (++seqnr == 0)
576: log("outgoing seqnr wraps around");
1.25 markus 577: buffer_clear(&outgoing_packet);
578:
1.57 markus 579: if (type == SSH2_MSG_NEWKEYS)
580: set_newkeys(MODE_OUT);
1.25 markus 581: }
582:
583: void
584: packet_send()
585: {
1.62 markus 586: if (compat20)
1.25 markus 587: packet_send2();
588: else
589: packet_send1();
590: DBG(debug("packet_send done"));
591: }
592:
593: /*
1.16 markus 594: * Waits until a packet has been received, and returns its type. Note that
595: * no other data is processed until this returns, so this function should not
596: * be used during the interactive session.
597: */
1.1 deraadt 598:
1.2 provos 599: int
600: packet_read(int *payload_len_ptr)
1.1 deraadt 601: {
1.14 markus 602: int type, len;
1.56 millert 603: fd_set *setp;
1.14 markus 604: char buf[8192];
1.25 markus 605: DBG(debug("packet_read()"));
1.14 markus 606:
1.56 millert 607: setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) *
608: sizeof(fd_mask));
609:
1.14 markus 610: /* Since we are blocking, ensure that all written packets have been sent. */
611: packet_write_wait();
612:
613: /* Stay in the loop until we have received a complete packet. */
614: for (;;) {
615: /* Try to read a packet from the buffer. */
616: type = packet_read_poll(payload_len_ptr);
1.62 markus 617: if (!compat20 && (
1.32 markus 618: type == SSH_SMSG_SUCCESS
1.14 markus 619: || type == SSH_SMSG_FAILURE
620: || type == SSH_CMSG_EOF
1.32 markus 621: || type == SSH_CMSG_EXIT_CONFIRMATION))
1.14 markus 622: packet_integrity_check(*payload_len_ptr, 0, type);
623: /* If we got a packet, return it. */
1.56 millert 624: if (type != SSH_MSG_NONE) {
625: xfree(setp);
1.14 markus 626: return type;
1.56 millert 627: }
1.16 markus 628: /*
629: * Otherwise, wait for some data to arrive, add it to the
630: * buffer, and try again.
631: */
1.56 millert 632: memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
633: sizeof(fd_mask));
634: FD_SET(connection_in, setp);
1.16 markus 635:
1.14 markus 636: /* Wait for some data to arrive. */
1.56 millert 637: while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
1.51 deraadt 638: (errno == EAGAIN || errno == EINTR))
639: ;
1.16 markus 640:
1.14 markus 641: /* Read data from the socket. */
642: len = read(connection_in, buf, sizeof(buf));
1.18 markus 643: if (len == 0) {
644: log("Connection closed by %.200s", get_remote_ipaddr());
645: fatal_cleanup();
646: }
1.14 markus 647: if (len < 0)
648: fatal("Read from socket failed: %.100s", strerror(errno));
649: /* Append it to the buffer. */
650: packet_process_incoming(buf, len);
651: }
652: /* NOTREACHED */
1.1 deraadt 653: }
654:
1.16 markus 655: /*
656: * Waits until a packet has been received, verifies that its type matches
657: * that given, and gives a fatal error and exits if there is a mismatch.
658: */
1.1 deraadt 659:
1.2 provos 660: void
661: packet_read_expect(int *payload_len_ptr, int expected_type)
1.1 deraadt 662: {
1.14 markus 663: int type;
1.1 deraadt 664:
1.14 markus 665: type = packet_read(payload_len_ptr);
666: if (type != expected_type)
667: packet_disconnect("Protocol error: expected packet type %d, got %d",
1.25 markus 668: expected_type, type);
1.1 deraadt 669: }
670:
671: /* Checks if a full packet is available in the data received so far via
1.14 markus 672: * packet_process_incoming. If so, reads the packet; otherwise returns
673: * SSH_MSG_NONE. This does not wait for data from the connection.
674: *
675: * SSH_MSG_DISCONNECT is handled specially here. Also,
676: * SSH_MSG_IGNORE messages are skipped by this function and are never returned
677: * to higher levels.
678: *
679: * The returned payload_len does include space consumed by:
680: * Packet length
681: * Padding
682: * Packet type
683: * Check bytes
684: */
1.1 deraadt 685:
1.2 provos 686: int
1.25 markus 687: packet_read_poll1(int *payload_len_ptr)
1.1 deraadt 688: {
1.40 markus 689: u_int len, padded_len;
1.62 markus 690: u_char *ucp, type;
691: char *cp;
1.40 markus 692: u_int checksum, stored_checksum;
1.14 markus 693:
694: /* Check if input size is less than minimum packet size. */
695: if (buffer_len(&input) < 4 + 8)
696: return SSH_MSG_NONE;
697: /* Get length of incoming packet. */
1.40 markus 698: ucp = (u_char *) buffer_ptr(&input);
1.14 markus 699: len = GET_32BIT(ucp);
700: if (len < 1 + 2 + 2 || len > 256 * 1024)
701: packet_disconnect("Bad packet length %d.", len);
702: padded_len = (len + 8) & ~7;
703:
704: /* Check if the packet has been entirely received. */
705: if (buffer_len(&input) < 4 + padded_len)
706: return SSH_MSG_NONE;
707:
708: /* The entire packet is in buffer. */
709:
710: /* Consume packet length. */
711: buffer_consume(&input, 4);
712:
1.62 markus 713: /*
714: * Cryptographic attack detector for ssh
715: * (C)1998 CORE-SDI, Buenos Aires Argentina
716: * Ariel Futoransky(futo@core-sdi.com)
717: */
718: if (receive_context.cipher->number != SSH_CIPHER_NONE &&
719: detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED)
720: packet_disconnect("crc32 compensation attack: network attack detected");
721:
722: /* Decrypt data to incoming_packet. */
1.14 markus 723: buffer_clear(&incoming_packet);
724: buffer_append_space(&incoming_packet, &cp, padded_len);
1.62 markus 725: cipher_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
726:
1.14 markus 727: buffer_consume(&input, padded_len);
1.1 deraadt 728:
729: #ifdef PACKET_DEBUG
1.14 markus 730: fprintf(stderr, "read_poll plain: ");
731: buffer_dump(&incoming_packet);
1.1 deraadt 732: #endif
733:
1.14 markus 734: /* Compute packet checksum. */
1.40 markus 735: checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet),
1.25 markus 736: buffer_len(&incoming_packet) - 4);
1.14 markus 737:
738: /* Skip padding. */
739: buffer_consume(&incoming_packet, 8 - len % 8);
740:
741: /* Test check bytes. */
742: if (len != buffer_len(&incoming_packet))
743: packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
1.25 markus 744: len, buffer_len(&incoming_packet));
1.14 markus 745:
1.40 markus 746: ucp = (u_char *) buffer_ptr(&incoming_packet) + len - 4;
1.14 markus 747: stored_checksum = GET_32BIT(ucp);
748: if (checksum != stored_checksum)
749: packet_disconnect("Corrupted check bytes on input.");
750: buffer_consume_end(&incoming_packet, 4);
751:
752: if (packet_compression) {
753: buffer_clear(&compression_buffer);
754: buffer_uncompress(&incoming_packet, &compression_buffer);
755: buffer_clear(&incoming_packet);
756: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1.25 markus 757: buffer_len(&compression_buffer));
1.14 markus 758: }
1.62 markus 759: type = buffer_get_char(&incoming_packet);
1.14 markus 760: *payload_len_ptr = buffer_len(&incoming_packet);
1.62 markus 761: return type;
1.1 deraadt 762: }
1.14 markus 763:
1.25 markus 764: int
765: packet_read_poll2(int *payload_len_ptr)
766: {
1.50 markus 767: static u_int32_t seqnr = 0;
768: static u_int packet_length = 0;
1.40 markus 769: u_int padlen, need;
1.62 markus 770: u_char *macbuf, *ucp, type;
1.25 markus 771: char *cp;
772: int maclen, block_size;
773: Enc *enc = NULL;
774: Mac *mac = NULL;
775: Comp *comp = NULL;
776:
1.57 markus 777: if (newkeys[MODE_IN] != NULL) {
778: enc = &newkeys[MODE_IN]->enc;
779: mac = &newkeys[MODE_IN]->mac;
780: comp = &newkeys[MODE_IN]->comp;
1.25 markus 781: }
782: maclen = mac && mac->enabled ? mac->mac_len : 0;
1.37 markus 783: block_size = enc ? enc->cipher->block_size : 8;
1.25 markus 784:
785: if (packet_length == 0) {
786: /*
787: * check if input size is less than the cipher block size,
788: * decrypt first block and extract length of incoming packet
789: */
790: if (buffer_len(&input) < block_size)
791: return SSH_MSG_NONE;
792: buffer_clear(&incoming_packet);
793: buffer_append_space(&incoming_packet, &cp, block_size);
1.62 markus 794: cipher_decrypt(&receive_context, cp, buffer_ptr(&input),
1.25 markus 795: block_size);
1.40 markus 796: ucp = (u_char *) buffer_ptr(&incoming_packet);
1.25 markus 797: packet_length = GET_32BIT(ucp);
798: if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
799: buffer_dump(&incoming_packet);
800: packet_disconnect("Bad packet length %d.", packet_length);
801: }
802: DBG(debug("input: packet len %d", packet_length+4));
803: buffer_consume(&input, block_size);
804: }
805: /* we have a partial packet of block_size bytes */
806: need = 4 + packet_length - block_size;
807: DBG(debug("partial packet %d, need %d, maclen %d", block_size,
808: need, maclen));
809: if (need % block_size != 0)
810: fatal("padding error: need %d block %d mod %d",
811: need, block_size, need % block_size);
812: /*
813: * check if the entire packet has been received and
814: * decrypt into incoming_packet
815: */
816: if (buffer_len(&input) < need + maclen)
817: return SSH_MSG_NONE;
818: #ifdef PACKET_DEBUG
819: fprintf(stderr, "read_poll enc/full: ");
820: buffer_dump(&input);
821: #endif
822: buffer_append_space(&incoming_packet, &cp, need);
1.62 markus 823: cipher_decrypt(&receive_context, cp, buffer_ptr(&input), need);
1.25 markus 824: buffer_consume(&input, need);
825: /*
826: * compute MAC over seqnr and packet,
827: * increment sequence number for incoming packet
828: */
1.29 markus 829: if (mac && mac->enabled) {
1.50 markus 830: macbuf = mac_compute(mac, seqnr,
1.40 markus 831: (u_char *) buffer_ptr(&incoming_packet),
1.50 markus 832: buffer_len(&incoming_packet));
1.25 markus 833: if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1.36 markus 834: packet_disconnect("Corrupted MAC on input.");
835: DBG(debug("MAC #%d ok", seqnr));
1.25 markus 836: buffer_consume(&input, mac->mac_len);
837: }
1.29 markus 838: if (++seqnr == 0)
839: log("incoming seqnr wraps around");
1.25 markus 840:
841: /* get padlen */
842: cp = buffer_ptr(&incoming_packet) + 4;
1.62 markus 843: padlen = (u_char) *cp;
1.25 markus 844: DBG(debug("input: padlen %d", padlen));
845: if (padlen < 4)
846: packet_disconnect("Corrupted padlen %d on input.", padlen);
847:
848: /* skip packet size + padlen, discard padding */
849: buffer_consume(&incoming_packet, 4 + 1);
850: buffer_consume_end(&incoming_packet, padlen);
851:
852: DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
853: if (comp && comp->enabled) {
854: buffer_clear(&compression_buffer);
855: buffer_uncompress(&incoming_packet, &compression_buffer);
856: buffer_clear(&incoming_packet);
857: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
858: buffer_len(&compression_buffer));
859: DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
860: }
861: /*
862: * get packet type, implies consume.
863: * return length of payload (without type field)
864: */
1.62 markus 865: type = buffer_get_char(&incoming_packet);
1.57 markus 866: if (type == SSH2_MSG_NEWKEYS)
867: set_newkeys(MODE_IN);
1.62 markus 868: *payload_len_ptr = buffer_len(&incoming_packet);
1.25 markus 869: #ifdef PACKET_DEBUG
1.55 deraadt 870: fprintf(stderr, "read/plain[%d]:\r\n", type);
1.25 markus 871: buffer_dump(&incoming_packet);
872: #endif
1.62 markus 873: /* reset for next packet */
874: packet_length = 0;
875: return type;
1.25 markus 876: }
877:
878: int
879: packet_read_poll(int *payload_len_ptr)
880: {
1.62 markus 881: int reason;
882: u_char type;
1.25 markus 883: char *msg;
1.62 markus 884:
1.25 markus 885: for (;;) {
1.62 markus 886: if (compat20) {
887: type = packet_read_poll2(payload_len_ptr);
888: if (type)
1.25 markus 889: DBG(debug("received packet type %d", type));
890: switch(type) {
891: case SSH2_MSG_IGNORE:
892: break;
893: case SSH2_MSG_DEBUG:
894: packet_get_char();
895: msg = packet_get_string(NULL);
896: debug("Remote: %.900s", msg);
897: xfree(msg);
898: msg = packet_get_string(NULL);
899: xfree(msg);
900: break;
901: case SSH2_MSG_DISCONNECT:
902: reason = packet_get_int();
903: msg = packet_get_string(NULL);
1.41 markus 904: log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(),
905: reason, msg);
1.25 markus 906: xfree(msg);
907: fatal_cleanup();
908: break;
909: default:
910: return type;
911: break;
1.48 stevesk 912: }
1.25 markus 913: } else {
1.62 markus 914: type = packet_read_poll1(payload_len_ptr);
1.25 markus 915: switch(type) {
916: case SSH_MSG_IGNORE:
917: break;
918: case SSH_MSG_DEBUG:
919: msg = packet_get_string(NULL);
920: debug("Remote: %.900s", msg);
921: xfree(msg);
922: break;
923: case SSH_MSG_DISCONNECT:
924: msg = packet_get_string(NULL);
1.41 markus 925: log("Received disconnect from %s: %.400s", get_remote_ipaddr(),
926: msg);
1.25 markus 927: fatal_cleanup();
928: xfree(msg);
929: break;
930: default:
1.62 markus 931: if (type)
1.25 markus 932: DBG(debug("received packet type %d", type));
933: return type;
934: break;
1.48 stevesk 935: }
1.25 markus 936: }
937: }
938: }
939:
1.16 markus 940: /*
941: * Buffers the given amount of input characters. This is intended to be used
942: * together with packet_read_poll.
943: */
1.1 deraadt 944:
1.2 provos 945: void
1.40 markus 946: packet_process_incoming(const char *buf, u_int len)
1.1 deraadt 947: {
1.14 markus 948: buffer_append(&input, buf, len);
1.1 deraadt 949: }
950:
951: /* Returns a character from the packet. */
952:
1.40 markus 953: u_int
1.2 provos 954: packet_get_char()
1.1 deraadt 955: {
1.14 markus 956: char ch;
957: buffer_get(&incoming_packet, &ch, 1);
1.40 markus 958: return (u_char) ch;
1.1 deraadt 959: }
960:
961: /* Returns an integer from the packet data. */
962:
1.40 markus 963: u_int
1.2 provos 964: packet_get_int()
1.1 deraadt 965: {
1.14 markus 966: return buffer_get_int(&incoming_packet);
1.1 deraadt 967: }
968:
1.16 markus 969: /*
970: * Returns an arbitrary precision integer from the packet data. The integer
971: * must have been initialized before this call.
972: */
1.1 deraadt 973:
1.2 provos 974: void
1.14 markus 975: packet_get_bignum(BIGNUM * value, int *length_ptr)
1.1 deraadt 976: {
1.14 markus 977: *length_ptr = buffer_get_bignum(&incoming_packet, value);
1.24 markus 978: }
979:
980: void
981: packet_get_bignum2(BIGNUM * value, int *length_ptr)
982: {
983: *length_ptr = buffer_get_bignum2(&incoming_packet, value);
984: }
985:
986: char *
987: packet_get_raw(int *length_ptr)
988: {
989: int bytes = buffer_len(&incoming_packet);
990: if (length_ptr != NULL)
991: *length_ptr = bytes;
992: return buffer_ptr(&incoming_packet);
1.28 markus 993: }
994:
995: int
996: packet_remaining(void)
997: {
998: return buffer_len(&incoming_packet);
1.1 deraadt 999: }
1000:
1.16 markus 1001: /*
1002: * Returns a string from the packet data. The string is allocated using
1003: * xmalloc; it is the responsibility of the calling program to free it when
1004: * no longer needed. The length_ptr argument may be NULL, or point to an
1005: * integer into which the length of the string is stored.
1006: */
1.1 deraadt 1007:
1.16 markus 1008: char *
1.40 markus 1009: packet_get_string(u_int *length_ptr)
1.1 deraadt 1010: {
1.14 markus 1011: return buffer_get_string(&incoming_packet, length_ptr);
1.1 deraadt 1012: }
1013:
1.16 markus 1014: /*
1015: * Sends a diagnostic message from the server to the client. This message
1016: * can be sent at any time (but not while constructing another message). The
1017: * message is printed immediately, but only if the client is being executed
1018: * in verbose mode. These messages are primarily intended to ease debugging
1019: * authentication problems. The length of the formatted message must not
1020: * exceed 1024 bytes. This will automatically call packet_write_wait.
1021: */
1.1 deraadt 1022:
1.2 provos 1023: void
1.14 markus 1024: packet_send_debug(const char *fmt,...)
1.1 deraadt 1025: {
1.14 markus 1026: char buf[1024];
1027: va_list args;
1.39 markus 1028:
1029: if (compat20 && (datafellows & SSH_BUG_DEBUG))
1030: return;
1.14 markus 1031:
1032: va_start(args, fmt);
1033: vsnprintf(buf, sizeof(buf), fmt, args);
1034: va_end(args);
1035:
1.30 markus 1036: if (compat20) {
1037: packet_start(SSH2_MSG_DEBUG);
1038: packet_put_char(0); /* bool: always display */
1039: packet_put_cstring(buf);
1040: packet_put_cstring("");
1041: } else {
1042: packet_start(SSH_MSG_DEBUG);
1043: packet_put_cstring(buf);
1044: }
1.14 markus 1045: packet_send();
1046: packet_write_wait();
1.1 deraadt 1047: }
1048:
1.16 markus 1049: /*
1050: * Logs the error plus constructs and sends a disconnect packet, closes the
1051: * connection, and exits. This function never returns. The error message
1052: * should not contain a newline. The length of the formatted message must
1053: * not exceed 1024 bytes.
1054: */
1.1 deraadt 1055:
1.2 provos 1056: void
1.14 markus 1057: packet_disconnect(const char *fmt,...)
1.1 deraadt 1058: {
1.14 markus 1059: char buf[1024];
1060: va_list args;
1061: static int disconnecting = 0;
1062: if (disconnecting) /* Guard against recursive invocations. */
1063: fatal("packet_disconnect called recursively.");
1064: disconnecting = 1;
1065:
1.16 markus 1066: /*
1067: * Format the message. Note that the caller must make sure the
1068: * message is of limited size.
1069: */
1.14 markus 1070: va_start(args, fmt);
1071: vsnprintf(buf, sizeof(buf), fmt, args);
1072: va_end(args);
1073:
1074: /* Send the disconnect message to the other side, and wait for it to get sent. */
1.25 markus 1075: if (compat20) {
1076: packet_start(SSH2_MSG_DISCONNECT);
1077: packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1078: packet_put_cstring(buf);
1079: packet_put_cstring("");
1080: } else {
1081: packet_start(SSH_MSG_DISCONNECT);
1.65 markus 1082: packet_put_cstring(buf);
1.25 markus 1083: }
1.14 markus 1084: packet_send();
1085: packet_write_wait();
1086:
1087: /* Stop listening for connections. */
1088: channel_stop_listening();
1089:
1090: /* Close the connection. */
1091: packet_close();
1.1 deraadt 1092:
1.14 markus 1093: /* Display the error locally and exit. */
1.17 markus 1094: log("Disconnecting: %.100s", buf);
1095: fatal_cleanup();
1.1 deraadt 1096: }
1097:
1.16 markus 1098: /* Checks if there is any buffered output, and tries to write some of the output. */
1.1 deraadt 1099:
1.2 provos 1100: void
1101: packet_write_poll()
1.1 deraadt 1102: {
1.14 markus 1103: int len = buffer_len(&output);
1104: if (len > 0) {
1105: len = write(connection_out, buffer_ptr(&output), len);
1106: if (len <= 0) {
1107: if (errno == EAGAIN)
1108: return;
1109: else
1110: fatal("Write failed: %.100s", strerror(errno));
1111: }
1112: buffer_consume(&output, len);
1113: }
1.1 deraadt 1114: }
1115:
1.16 markus 1116: /*
1117: * Calls packet_write_poll repeatedly until all pending output data has been
1118: * written.
1119: */
1.1 deraadt 1120:
1.2 provos 1121: void
1122: packet_write_wait()
1.1 deraadt 1123: {
1.56 millert 1124: fd_set *setp;
1125:
1126: setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) *
1127: sizeof(fd_mask));
1.14 markus 1128: packet_write_poll();
1129: while (packet_have_data_to_write()) {
1.56 millert 1130: memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1131: sizeof(fd_mask));
1132: FD_SET(connection_out, setp);
1133: while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1.51 deraadt 1134: (errno == EAGAIN || errno == EINTR))
1135: ;
1.14 markus 1136: packet_write_poll();
1137: }
1.56 millert 1138: xfree(setp);
1.1 deraadt 1139: }
1140:
1141: /* Returns true if there is buffered data to write to the connection. */
1142:
1.2 provos 1143: int
1144: packet_have_data_to_write()
1.1 deraadt 1145: {
1.14 markus 1146: return buffer_len(&output) != 0;
1.1 deraadt 1147: }
1148:
1149: /* Returns true if there is not too much data to write to the connection. */
1150:
1.2 provos 1151: int
1152: packet_not_very_much_data_to_write()
1.1 deraadt 1153: {
1.14 markus 1154: if (interactive_mode)
1155: return buffer_len(&output) < 16384;
1156: else
1157: return buffer_len(&output) < 128 * 1024;
1.1 deraadt 1158: }
1159:
1160: /* Informs that the current session is interactive. Sets IP flags for that. */
1161:
1.2 provos 1162: void
1.43 markus 1163: packet_set_interactive(int interactive)
1.1 deraadt 1164: {
1.43 markus 1165: static int called = 0;
1.44 markus 1166: int lowdelay = IPTOS_LOWDELAY;
1167: int throughput = IPTOS_THROUGHPUT;
1168: int on = 1;
1169:
1.43 markus 1170: if (called)
1171: return;
1172: called = 1;
1.1 deraadt 1173:
1.14 markus 1174: /* Record that we are in interactive mode. */
1175: interactive_mode = interactive;
1.1 deraadt 1176:
1.19 markus 1177: /* Only set socket options if using a socket. */
1178: if (!packet_connection_is_on_socket())
1.14 markus 1179: return;
1.19 markus 1180: /*
1.42 markus 1181: * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only
1.19 markus 1182: */
1.14 markus 1183: if (interactive) {
1.16 markus 1184: /*
1185: * Set IP options for an interactive connection. Use
1186: * IPTOS_LOWDELAY and TCP_NODELAY.
1187: */
1.42 markus 1188: if (packet_connection_is_ipv4()) {
1189: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS,
1190: (void *) &lowdelay, sizeof(lowdelay)) < 0)
1191: error("setsockopt IPTOS_LOWDELAY: %.100s",
1192: strerror(errno));
1193: }
1.14 markus 1194: if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on,
1.19 markus 1195: sizeof(on)) < 0)
1.14 markus 1196: error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
1.42 markus 1197: } else if (packet_connection_is_ipv4()) {
1.16 markus 1198: /*
1199: * Set IP options for a non-interactive connection. Use
1200: * IPTOS_THROUGHPUT.
1201: */
1.14 markus 1202: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput,
1.19 markus 1203: sizeof(throughput)) < 0)
1.14 markus 1204: error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1205: }
1.1 deraadt 1206: }
1207:
1208: /* Returns true if the current connection is interactive. */
1209:
1.2 provos 1210: int
1211: packet_is_interactive()
1.1 deraadt 1212: {
1.14 markus 1213: return interactive_mode;
1.12 markus 1214: }
1215:
1216: int
1217: packet_set_maxsize(int s)
1218: {
1.14 markus 1219: static int called = 0;
1220: if (called) {
1.25 markus 1221: log("packet_set_maxsize: called twice: old %d new %d",
1222: max_packet_size, s);
1.14 markus 1223: return -1;
1224: }
1225: if (s < 4 * 1024 || s > 1024 * 1024) {
1226: log("packet_set_maxsize: bad size %d", s);
1227: return -1;
1228: }
1.66 ! markus 1229: debug("packet_set_maxsize: setting to %d", s);
1.14 markus 1230: max_packet_size = s;
1231: return s;
1.53 markus 1232: }
1233:
1234: /*
1235: * 9.2. Ignored Data Message
1.61 markus 1236: *
1.53 markus 1237: * byte SSH_MSG_IGNORE
1238: * string data
1.61 markus 1239: *
1.53 markus 1240: * All implementations MUST understand (and ignore) this message at any
1241: * time (after receiving the protocol version). No implementation is
1242: * required to send them. This message can be used as an additional
1243: * protection measure against advanced traffic analysis techniques.
1244: */
1245: /* size of current + ignore message should be n*sumlen bytes (w/o mac) */
1246: void
1247: packet_inject_ignore(int sumlen)
1248: {
1.54 markus 1249: int blocksize, padlen, have, need, nb, mini, nbytes;
1.53 markus 1250: Enc *enc = NULL;
1251:
1.62 markus 1252: if (compat20 == 0)
1.53 markus 1253: return;
1254:
1255: have = buffer_len(&outgoing_packet);
1256: debug2("packet_inject_ignore: current %d", have);
1.57 markus 1257: if (newkeys[MODE_OUT] != NULL)
1258: enc = &newkeys[MODE_OUT]->enc;
1.53 markus 1259: blocksize = enc ? enc->cipher->block_size : 8;
1260: padlen = blocksize - (have % blocksize);
1261: if (padlen < 4)
1262: padlen += blocksize;
1263: have += padlen;
1264: have /= blocksize; /* # of blocks for current message */
1265:
1266: nb = roundup(sumlen, blocksize) / blocksize; /* blocks for both */
1267: mini = roundup(5+1+4+4, blocksize) / blocksize; /* minsize ignore msg */
1268: need = nb - (have % nb); /* blocks for ignore */
1269: if (need <= mini)
1270: need += nb;
1271: nbytes = (need - mini) * blocksize; /* size of ignore payload */
1272: debug2("packet_inject_ignore: block %d have %d nb %d mini %d need %d",
1273: blocksize, have, nb, mini, need);
1274:
1275: /* enqueue current message and append a ignore message */
1276: packet_send();
1.54 markus 1277: packet_send_ignore(nbytes);
1278: }
1279:
1280: void
1281: packet_send_ignore(int nbytes)
1282: {
1283: u_int32_t rand = 0;
1284: int i;
1285:
1286: packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1.53 markus 1287: packet_put_int(nbytes);
1288: for(i = 0; i < nbytes; i++) {
1289: if (i % 4 == 0)
1290: rand = arc4random();
1291: packet_put_char(rand & 0xff);
1292: rand >>= 8;
1293: }
1.1 deraadt 1294: }
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