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 1.109 2003/07/10 14:42:28 markus Exp $"); 41 42 #include <sys/queue.h> 43 44 #include "xmalloc.h" 45 #include "buffer.h" 46 #include "packet.h" 47 #include "bufaux.h" 48 #include "crc32.h" 49 #include "getput.h" 50 51 #include "compress.h" 52 #include "deattack.h" 53 #include "channels.h" 54 55 #include "compat.h" 56 #include "ssh1.h" 57 #include "ssh2.h" 58 59 #include "cipher.h" 60 #include "kex.h" 61 #include "mac.h" 62 #include "log.h" 63 #include "canohost.h" 64 #include "misc.h" 65 #include "ssh.h" 66 67 #ifdef PACKET_DEBUG 68 #define DBG(x) x 69 #else 70 #define DBG(x) 71 #endif 72 73 /* 74 * This variable contains the file descriptors used for communicating with 75 * the other side. connection_in is used for reading; connection_out for 76 * writing. These can be the same descriptor, in which case it is assumed to 77 * be a socket. 78 */ 79 static int connection_in = -1; 80 static int connection_out = -1; 81 82 /* Protocol flags for the remote side. */ 83 static u_int remote_protocol_flags = 0; 84 85 /* Encryption context for receiving data. This is only used for decryption. */ 86 static CipherContext receive_context; 87 88 /* Encryption context for sending data. This is only used for encryption. */ 89 static CipherContext send_context; 90 91 /* Buffer for raw input data from the socket. */ 92 Buffer input; 93 94 /* Buffer for raw output data going to the socket. */ 95 Buffer output; 96 97 /* Buffer for the partial outgoing packet being constructed. */ 98 static Buffer outgoing_packet; 99 100 /* Buffer for the incoming packet currently being processed. */ 101 static Buffer incoming_packet; 102 103 /* Scratch buffer for packet compression/decompression. */ 104 static Buffer compression_buffer; 105 static int compression_buffer_ready = 0; 106 107 /* Flag indicating whether packet compression/decompression is enabled. */ 108 static int packet_compression = 0; 109 110 /* default maximum packet size */ 111 u_int max_packet_size = 32768; 112 113 /* Flag indicating whether this module has been initialized. */ 114 static int initialized = 0; 115 116 /* Set to true if the connection is interactive. */ 117 static int interactive_mode = 0; 118 119 /* Session key information for Encryption and MAC */ 120 Newkeys *newkeys[MODE_MAX]; 121 static struct packet_state { 122 u_int32_t seqnr; 123 u_int32_t packets; 124 u_int64_t blocks; 125 } p_read, p_send; 126 127 static u_int64_t max_blocks_in, max_blocks_out; 128 static u_int32_t rekey_limit; 129 130 /* Session key for protocol v1 */ 131 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; 132 static u_int ssh1_keylen; 133 134 /* roundup current message to extra_pad bytes */ 135 static u_char extra_pad = 0; 136 137 struct packet { 138 TAILQ_ENTRY(packet) next; 139 u_char type; 140 Buffer payload; 141 }; 142 TAILQ_HEAD(, packet) outgoing; 143 144 /* 145 * Sets the descriptors used for communication. Disables encryption until 146 * packet_set_encryption_key is called. 147 */ 148 void 149 packet_set_connection(int fd_in, int fd_out) 150 { 151 Cipher *none = cipher_by_name("none"); 152 153 if (none == NULL) 154 fatal("packet_set_connection: cannot load cipher 'none'"); 155 connection_in = fd_in; 156 connection_out = fd_out; 157 cipher_init(&send_context, none, "", 0, NULL, 0, CIPHER_ENCRYPT); 158 cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); 159 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; 160 if (!initialized) { 161 initialized = 1; 162 buffer_init(&input); 163 buffer_init(&output); 164 buffer_init(&outgoing_packet); 165 buffer_init(&incoming_packet); 166 TAILQ_INIT(&outgoing); 167 } 168 /* Kludge: arrange the close function to be called from fatal(). */ 169 fatal_add_cleanup((void (*) (void *)) packet_close, NULL); 170 } 171 172 /* Returns 1 if remote host is connected via socket, 0 if not. */ 173 174 int 175 packet_connection_is_on_socket(void) 176 { 177 struct sockaddr_storage from, to; 178 socklen_t fromlen, tolen; 179 180 /* filedescriptors in and out are the same, so it's a socket */ 181 if (connection_in == connection_out) 182 return 1; 183 fromlen = sizeof(from); 184 memset(&from, 0, sizeof(from)); 185 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) 186 return 0; 187 tolen = sizeof(to); 188 memset(&to, 0, sizeof(to)); 189 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) 190 return 0; 191 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) 192 return 0; 193 if (from.ss_family != AF_INET && from.ss_family != AF_INET6) 194 return 0; 195 return 1; 196 } 197 198 /* 199 * Exports an IV from the CipherContext required to export the key 200 * state back from the unprivileged child to the privileged parent 201 * process. 202 */ 203 204 void 205 packet_get_keyiv(int mode, u_char *iv, u_int len) 206 { 207 CipherContext *cc; 208 209 if (mode == MODE_OUT) 210 cc = &send_context; 211 else 212 cc = &receive_context; 213 214 cipher_get_keyiv(cc, iv, len); 215 } 216 217 int 218 packet_get_keycontext(int mode, u_char *dat) 219 { 220 CipherContext *cc; 221 222 if (mode == MODE_OUT) 223 cc = &send_context; 224 else 225 cc = &receive_context; 226 227 return (cipher_get_keycontext(cc, dat)); 228 } 229 230 void 231 packet_set_keycontext(int mode, u_char *dat) 232 { 233 CipherContext *cc; 234 235 if (mode == MODE_OUT) 236 cc = &send_context; 237 else 238 cc = &receive_context; 239 240 cipher_set_keycontext(cc, dat); 241 } 242 243 int 244 packet_get_keyiv_len(int mode) 245 { 246 CipherContext *cc; 247 248 if (mode == MODE_OUT) 249 cc = &send_context; 250 else 251 cc = &receive_context; 252 253 return (cipher_get_keyiv_len(cc)); 254 } 255 void 256 packet_set_iv(int mode, u_char *dat) 257 { 258 CipherContext *cc; 259 260 if (mode == MODE_OUT) 261 cc = &send_context; 262 else 263 cc = &receive_context; 264 265 cipher_set_keyiv(cc, dat); 266 } 267 int 268 packet_get_ssh1_cipher(void) 269 { 270 return (cipher_get_number(receive_context.cipher)); 271 } 272 273 void 274 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets) 275 { 276 struct packet_state *state; 277 278 state = (mode == MODE_IN) ? &p_read : &p_send; 279 *seqnr = state->seqnr; 280 *blocks = state->blocks; 281 *packets = state->packets; 282 } 283 284 void 285 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets) 286 { 287 struct packet_state *state; 288 289 state = (mode == MODE_IN) ? &p_read : &p_send; 290 state->seqnr = seqnr; 291 state->blocks = blocks; 292 state->packets = packets; 293 } 294 295 /* returns 1 if connection is via ipv4 */ 296 297 int 298 packet_connection_is_ipv4(void) 299 { 300 struct sockaddr_storage to; 301 socklen_t tolen = sizeof(to); 302 303 memset(&to, 0, sizeof(to)); 304 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) 305 return 0; 306 if (to.ss_family != AF_INET) 307 return 0; 308 return 1; 309 } 310 311 /* Sets the connection into non-blocking mode. */ 312 313 void 314 packet_set_nonblocking(void) 315 { 316 /* Set the socket into non-blocking mode. */ 317 if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) 318 error("fcntl O_NONBLOCK: %.100s", strerror(errno)); 319 320 if (connection_out != connection_in) { 321 if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) 322 error("fcntl O_NONBLOCK: %.100s", strerror(errno)); 323 } 324 } 325 326 /* Returns the socket used for reading. */ 327 328 int 329 packet_get_connection_in(void) 330 { 331 return connection_in; 332 } 333 334 /* Returns the descriptor used for writing. */ 335 336 int 337 packet_get_connection_out(void) 338 { 339 return connection_out; 340 } 341 342 /* Closes the connection and clears and frees internal data structures. */ 343 344 void 345 packet_close(void) 346 { 347 if (!initialized) 348 return; 349 initialized = 0; 350 if (connection_in == connection_out) { 351 shutdown(connection_out, SHUT_RDWR); 352 close(connection_out); 353 } else { 354 close(connection_in); 355 close(connection_out); 356 } 357 buffer_free(&input); 358 buffer_free(&output); 359 buffer_free(&outgoing_packet); 360 buffer_free(&incoming_packet); 361 if (compression_buffer_ready) { 362 buffer_free(&compression_buffer); 363 buffer_compress_uninit(); 364 } 365 cipher_cleanup(&send_context); 366 cipher_cleanup(&receive_context); 367 } 368 369 /* Sets remote side protocol flags. */ 370 371 void 372 packet_set_protocol_flags(u_int protocol_flags) 373 { 374 remote_protocol_flags = protocol_flags; 375 } 376 377 /* Returns the remote protocol flags set earlier by the above function. */ 378 379 u_int 380 packet_get_protocol_flags(void) 381 { 382 return remote_protocol_flags; 383 } 384 385 /* 386 * Starts packet compression from the next packet on in both directions. 387 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. 388 */ 389 390 static void 391 packet_init_compression(void) 392 { 393 if (compression_buffer_ready == 1) 394 return; 395 compression_buffer_ready = 1; 396 buffer_init(&compression_buffer); 397 } 398 399 void 400 packet_start_compression(int level) 401 { 402 if (packet_compression && !compat20) 403 fatal("Compression already enabled."); 404 packet_compression = 1; 405 packet_init_compression(); 406 buffer_compress_init_send(level); 407 buffer_compress_init_recv(); 408 } 409 410 /* 411 * Causes any further packets to be encrypted using the given key. The same 412 * key is used for both sending and reception. However, both directions are 413 * encrypted independently of each other. 414 */ 415 416 void 417 packet_set_encryption_key(const u_char *key, u_int keylen, 418 int number) 419 { 420 Cipher *cipher = cipher_by_number(number); 421 422 if (cipher == NULL) 423 fatal("packet_set_encryption_key: unknown cipher number %d", number); 424 if (keylen < 20) 425 fatal("packet_set_encryption_key: keylen too small: %d", keylen); 426 if (keylen > SSH_SESSION_KEY_LENGTH) 427 fatal("packet_set_encryption_key: keylen too big: %d", keylen); 428 memcpy(ssh1_key, key, keylen); 429 ssh1_keylen = keylen; 430 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); 431 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); 432 } 433 434 u_int 435 packet_get_encryption_key(u_char *key) 436 { 437 if (key == NULL) 438 return (ssh1_keylen); 439 memcpy(key, ssh1_key, ssh1_keylen); 440 return (ssh1_keylen); 441 } 442 443 /* Start constructing a packet to send. */ 444 void 445 packet_start(u_char type) 446 { 447 u_char buf[9]; 448 int len; 449 450 DBG(debug("packet_start[%d]", type)); 451 len = compat20 ? 6 : 9; 452 memset(buf, 0, len - 1); 453 buf[len - 1] = type; 454 buffer_clear(&outgoing_packet); 455 buffer_append(&outgoing_packet, buf, len); 456 } 457 458 /* Append payload. */ 459 void 460 packet_put_char(int value) 461 { 462 char ch = value; 463 464 buffer_append(&outgoing_packet, &ch, 1); 465 } 466 void 467 packet_put_int(u_int value) 468 { 469 buffer_put_int(&outgoing_packet, value); 470 } 471 void 472 packet_put_string(const void *buf, u_int len) 473 { 474 buffer_put_string(&outgoing_packet, buf, len); 475 } 476 void 477 packet_put_cstring(const char *str) 478 { 479 buffer_put_cstring(&outgoing_packet, str); 480 } 481 void 482 packet_put_raw(const void *buf, u_int len) 483 { 484 buffer_append(&outgoing_packet, buf, len); 485 } 486 void 487 packet_put_bignum(BIGNUM * value) 488 { 489 buffer_put_bignum(&outgoing_packet, value); 490 } 491 void 492 packet_put_bignum2(BIGNUM * value) 493 { 494 buffer_put_bignum2(&outgoing_packet, value); 495 } 496 497 /* 498 * Finalizes and sends the packet. If the encryption key has been set, 499 * encrypts the packet before sending. 500 */ 501 502 static void 503 packet_send1(void) 504 { 505 u_char buf[8], *cp; 506 int i, padding, len; 507 u_int checksum; 508 u_int32_t rand = 0; 509 510 /* 511 * If using packet compression, compress the payload of the outgoing 512 * packet. 513 */ 514 if (packet_compression) { 515 buffer_clear(&compression_buffer); 516 /* Skip padding. */ 517 buffer_consume(&outgoing_packet, 8); 518 /* padding */ 519 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); 520 buffer_compress(&outgoing_packet, &compression_buffer); 521 buffer_clear(&outgoing_packet); 522 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 523 buffer_len(&compression_buffer)); 524 } 525 /* Compute packet length without padding (add checksum, remove padding). */ 526 len = buffer_len(&outgoing_packet) + 4 - 8; 527 528 /* Insert padding. Initialized to zero in packet_start1() */ 529 padding = 8 - len % 8; 530 if (!send_context.plaintext) { 531 cp = buffer_ptr(&outgoing_packet); 532 for (i = 0; i < padding; i++) { 533 if (i % 4 == 0) 534 rand = arc4random(); 535 cp[7 - i] = rand & 0xff; 536 rand >>= 8; 537 } 538 } 539 buffer_consume(&outgoing_packet, 8 - padding); 540 541 /* Add check bytes. */ 542 checksum = ssh_crc32(buffer_ptr(&outgoing_packet), 543 buffer_len(&outgoing_packet)); 544 PUT_32BIT(buf, checksum); 545 buffer_append(&outgoing_packet, buf, 4); 546 547 #ifdef PACKET_DEBUG 548 fprintf(stderr, "packet_send plain: "); 549 buffer_dump(&outgoing_packet); 550 #endif 551 552 /* Append to output. */ 553 PUT_32BIT(buf, len); 554 buffer_append(&output, buf, 4); 555 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 556 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 557 buffer_len(&outgoing_packet)); 558 559 #ifdef PACKET_DEBUG 560 fprintf(stderr, "encrypted: "); 561 buffer_dump(&output); 562 #endif 563 564 buffer_clear(&outgoing_packet); 565 566 /* 567 * Note that the packet is now only buffered in output. It won\'t be 568 * actually sent until packet_write_wait or packet_write_poll is 569 * called. 570 */ 571 } 572 573 void 574 set_newkeys(int mode) 575 { 576 Enc *enc; 577 Mac *mac; 578 Comp *comp; 579 CipherContext *cc; 580 u_int64_t *max_blocks; 581 int encrypt; 582 583 debug2("set_newkeys: mode %d", mode); 584 585 if (mode == MODE_OUT) { 586 cc = &send_context; 587 encrypt = CIPHER_ENCRYPT; 588 p_send.packets = p_send.blocks = 0; 589 max_blocks = &max_blocks_out; 590 } else { 591 cc = &receive_context; 592 encrypt = CIPHER_DECRYPT; 593 p_read.packets = p_read.blocks = 0; 594 max_blocks = &max_blocks_in; 595 } 596 if (newkeys[mode] != NULL) { 597 debug("set_newkeys: rekeying"); 598 cipher_cleanup(cc); 599 enc = &newkeys[mode]->enc; 600 mac = &newkeys[mode]->mac; 601 comp = &newkeys[mode]->comp; 602 memset(mac->key, 0, mac->key_len); 603 xfree(enc->name); 604 xfree(enc->iv); 605 xfree(enc->key); 606 xfree(mac->name); 607 xfree(mac->key); 608 xfree(comp->name); 609 xfree(newkeys[mode]); 610 } 611 newkeys[mode] = kex_get_newkeys(mode); 612 if (newkeys[mode] == NULL) 613 fatal("newkeys: no keys for mode %d", mode); 614 enc = &newkeys[mode]->enc; 615 mac = &newkeys[mode]->mac; 616 comp = &newkeys[mode]->comp; 617 if (mac->md != NULL) 618 mac->enabled = 1; 619 DBG(debug("cipher_init_context: %d", mode)); 620 cipher_init(cc, enc->cipher, enc->key, enc->key_len, 621 enc->iv, enc->block_size, encrypt); 622 /* Deleting the keys does not gain extra security */ 623 /* memset(enc->iv, 0, enc->block_size); 624 memset(enc->key, 0, enc->key_len); */ 625 if (comp->type != 0 && comp->enabled == 0) { 626 packet_init_compression(); 627 if (mode == MODE_OUT) 628 buffer_compress_init_send(6); 629 else 630 buffer_compress_init_recv(); 631 comp->enabled = 1; 632 } 633 /* 634 * The 2^(blocksize*2) limit is too expensive for 3DES, 635 * blowfish, etc, so enforce a 1GB limit for small blocksizes. 636 */ 637 if (enc->block_size >= 16) 638 *max_blocks = (u_int64_t)1 << (enc->block_size*2); 639 else 640 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; 641 if (rekey_limit) 642 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); 643 } 644 645 /* 646 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) 647 */ 648 static void 649 packet_send2_wrapped(void) 650 { 651 u_char type, *cp, *macbuf = NULL; 652 u_char padlen, pad; 653 u_int packet_length = 0; 654 u_int i, len; 655 u_int32_t rand = 0; 656 Enc *enc = NULL; 657 Mac *mac = NULL; 658 Comp *comp = NULL; 659 int block_size; 660 661 if (newkeys[MODE_OUT] != NULL) { 662 enc = &newkeys[MODE_OUT]->enc; 663 mac = &newkeys[MODE_OUT]->mac; 664 comp = &newkeys[MODE_OUT]->comp; 665 } 666 block_size = enc ? enc->block_size : 8; 667 668 cp = buffer_ptr(&outgoing_packet); 669 type = cp[5]; 670 671 #ifdef PACKET_DEBUG 672 fprintf(stderr, "plain: "); 673 buffer_dump(&outgoing_packet); 674 #endif 675 676 if (comp && comp->enabled) { 677 len = buffer_len(&outgoing_packet); 678 /* skip header, compress only payload */ 679 buffer_consume(&outgoing_packet, 5); 680 buffer_clear(&compression_buffer); 681 buffer_compress(&outgoing_packet, &compression_buffer); 682 buffer_clear(&outgoing_packet); 683 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); 684 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), 685 buffer_len(&compression_buffer)); 686 DBG(debug("compression: raw %d compressed %d", len, 687 buffer_len(&outgoing_packet))); 688 } 689 690 /* sizeof (packet_len + pad_len + payload) */ 691 len = buffer_len(&outgoing_packet); 692 693 /* 694 * calc size of padding, alloc space, get random data, 695 * minimum padding is 4 bytes 696 */ 697 padlen = block_size - (len % block_size); 698 if (padlen < 4) 699 padlen += block_size; 700 if (extra_pad) { 701 /* will wrap if extra_pad+padlen > 255 */ 702 extra_pad = roundup(extra_pad, block_size); 703 pad = extra_pad - ((len + padlen) % extra_pad); 704 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", 705 pad, len, padlen, extra_pad); 706 padlen += pad; 707 extra_pad = 0; 708 } 709 cp = buffer_append_space(&outgoing_packet, padlen); 710 if (enc && !send_context.plaintext) { 711 /* random padding */ 712 for (i = 0; i < padlen; i++) { 713 if (i % 4 == 0) 714 rand = arc4random(); 715 cp[i] = rand & 0xff; 716 rand >>= 8; 717 } 718 } else { 719 /* clear padding */ 720 memset(cp, 0, padlen); 721 } 722 /* packet_length includes payload, padding and padding length field */ 723 packet_length = buffer_len(&outgoing_packet) - 4; 724 cp = buffer_ptr(&outgoing_packet); 725 PUT_32BIT(cp, packet_length); 726 cp[4] = padlen; 727 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); 728 729 /* compute MAC over seqnr and packet(length fields, payload, padding) */ 730 if (mac && mac->enabled) { 731 macbuf = mac_compute(mac, p_send.seqnr, 732 buffer_ptr(&outgoing_packet), 733 buffer_len(&outgoing_packet)); 734 DBG(debug("done calc MAC out #%d", p_send.seqnr)); 735 } 736 /* encrypt packet and append to output buffer. */ 737 cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); 738 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), 739 buffer_len(&outgoing_packet)); 740 /* append unencrypted MAC */ 741 if (mac && mac->enabled) 742 buffer_append(&output, (char *)macbuf, mac->mac_len); 743 #ifdef PACKET_DEBUG 744 fprintf(stderr, "encrypted: "); 745 buffer_dump(&output); 746 #endif 747 /* increment sequence number for outgoing packets */ 748 if (++p_send.seqnr == 0) 749 logit("outgoing seqnr wraps around"); 750 if (++p_send.packets == 0) 751 if (!(datafellows & SSH_BUG_NOREKEY)) 752 fatal("XXX too many packets with same key"); 753 p_send.blocks += (packet_length + 4) / block_size; 754 buffer_clear(&outgoing_packet); 755 756 if (type == SSH2_MSG_NEWKEYS) 757 set_newkeys(MODE_OUT); 758 } 759 760 static void 761 packet_send2(void) 762 { 763 static int rekeying = 0; 764 struct packet *p; 765 u_char type, *cp; 766 767 cp = buffer_ptr(&outgoing_packet); 768 type = cp[5]; 769 770 /* during rekeying we can only send key exchange messages */ 771 if (rekeying) { 772 if (!((type >= SSH2_MSG_TRANSPORT_MIN) && 773 (type <= SSH2_MSG_TRANSPORT_MAX))) { 774 debug("enqueue packet: %u", type); 775 p = xmalloc(sizeof(*p)); 776 p->type = type; 777 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer)); 778 buffer_init(&outgoing_packet); 779 TAILQ_INSERT_TAIL(&outgoing, p, next); 780 return; 781 } 782 } 783 784 /* rekeying starts with sending KEXINIT */ 785 if (type == SSH2_MSG_KEXINIT) 786 rekeying = 1; 787 788 packet_send2_wrapped(); 789 790 /* after a NEWKEYS message we can send the complete queue */ 791 if (type == SSH2_MSG_NEWKEYS) { 792 rekeying = 0; 793 while ((p = TAILQ_FIRST(&outgoing))) { 794 type = p->type; 795 debug("dequeue packet: %u", type); 796 buffer_free(&outgoing_packet); 797 memcpy(&outgoing_packet, &p->payload, 798 sizeof(Buffer)); 799 TAILQ_REMOVE(&outgoing, p, next); 800 xfree(p); 801 packet_send2_wrapped(); 802 } 803 } 804 } 805 806 void 807 packet_send(void) 808 { 809 if (compat20) 810 packet_send2(); 811 else 812 packet_send1(); 813 DBG(debug("packet_send done")); 814 } 815 816 /* 817 * Waits until a packet has been received, and returns its type. Note that 818 * no other data is processed until this returns, so this function should not 819 * be used during the interactive session. 820 */ 821 822 int 823 packet_read_seqnr(u_int32_t *seqnr_p) 824 { 825 int type, len; 826 fd_set *setp; 827 char buf[8192]; 828 DBG(debug("packet_read()")); 829 830 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * 831 sizeof(fd_mask)); 832 833 /* Since we are blocking, ensure that all written packets have been sent. */ 834 packet_write_wait(); 835 836 /* Stay in the loop until we have received a complete packet. */ 837 for (;;) { 838 /* Try to read a packet from the buffer. */ 839 type = packet_read_poll_seqnr(seqnr_p); 840 if (!compat20 && ( 841 type == SSH_SMSG_SUCCESS 842 || type == SSH_SMSG_FAILURE 843 || type == SSH_CMSG_EOF 844 || type == SSH_CMSG_EXIT_CONFIRMATION)) 845 packet_check_eom(); 846 /* If we got a packet, return it. */ 847 if (type != SSH_MSG_NONE) { 848 xfree(setp); 849 return type; 850 } 851 /* 852 * Otherwise, wait for some data to arrive, add it to the 853 * buffer, and try again. 854 */ 855 memset(setp, 0, howmany(connection_in + 1, NFDBITS) * 856 sizeof(fd_mask)); 857 FD_SET(connection_in, setp); 858 859 /* Wait for some data to arrive. */ 860 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && 861 (errno == EAGAIN || errno == EINTR)) 862 ; 863 864 /* Read data from the socket. */ 865 len = read(connection_in, buf, sizeof(buf)); 866 if (len == 0) { 867 logit("Connection closed by %.200s", get_remote_ipaddr()); 868 fatal_cleanup(); 869 } 870 if (len < 0) 871 fatal("Read from socket failed: %.100s", strerror(errno)); 872 /* Append it to the buffer. */ 873 packet_process_incoming(buf, len); 874 } 875 /* NOTREACHED */ 876 } 877 878 int 879 packet_read(void) 880 { 881 return packet_read_seqnr(NULL); 882 } 883 884 /* 885 * Waits until a packet has been received, verifies that its type matches 886 * that given, and gives a fatal error and exits if there is a mismatch. 887 */ 888 889 void 890 packet_read_expect(int expected_type) 891 { 892 int type; 893 894 type = packet_read(); 895 if (type != expected_type) 896 packet_disconnect("Protocol error: expected packet type %d, got %d", 897 expected_type, type); 898 } 899 900 /* Checks if a full packet is available in the data received so far via 901 * packet_process_incoming. If so, reads the packet; otherwise returns 902 * SSH_MSG_NONE. This does not wait for data from the connection. 903 * 904 * SSH_MSG_DISCONNECT is handled specially here. Also, 905 * SSH_MSG_IGNORE messages are skipped by this function and are never returned 906 * to higher levels. 907 */ 908 909 static int 910 packet_read_poll1(void) 911 { 912 u_int len, padded_len; 913 u_char *cp, type; 914 u_int checksum, stored_checksum; 915 916 /* Check if input size is less than minimum packet size. */ 917 if (buffer_len(&input) < 4 + 8) 918 return SSH_MSG_NONE; 919 /* Get length of incoming packet. */ 920 cp = buffer_ptr(&input); 921 len = GET_32BIT(cp); 922 if (len < 1 + 2 + 2 || len > 256 * 1024) 923 packet_disconnect("Bad packet length %u.", len); 924 padded_len = (len + 8) & ~7; 925 926 /* Check if the packet has been entirely received. */ 927 if (buffer_len(&input) < 4 + padded_len) 928 return SSH_MSG_NONE; 929 930 /* The entire packet is in buffer. */ 931 932 /* Consume packet length. */ 933 buffer_consume(&input, 4); 934 935 /* 936 * Cryptographic attack detector for ssh 937 * (C)1998 CORE-SDI, Buenos Aires Argentina 938 * Ariel Futoransky(futo@core-sdi.com) 939 */ 940 if (!receive_context.plaintext && 941 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) 942 packet_disconnect("crc32 compensation attack: network attack detected"); 943 944 /* Decrypt data to incoming_packet. */ 945 buffer_clear(&incoming_packet); 946 cp = buffer_append_space(&incoming_packet, padded_len); 947 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); 948 949 buffer_consume(&input, padded_len); 950 951 #ifdef PACKET_DEBUG 952 fprintf(stderr, "read_poll plain: "); 953 buffer_dump(&incoming_packet); 954 #endif 955 956 /* Compute packet checksum. */ 957 checksum = ssh_crc32(buffer_ptr(&incoming_packet), 958 buffer_len(&incoming_packet) - 4); 959 960 /* Skip padding. */ 961 buffer_consume(&incoming_packet, 8 - len % 8); 962 963 /* Test check bytes. */ 964 if (len != buffer_len(&incoming_packet)) 965 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", 966 len, buffer_len(&incoming_packet)); 967 968 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; 969 stored_checksum = GET_32BIT(cp); 970 if (checksum != stored_checksum) 971 packet_disconnect("Corrupted check bytes on input."); 972 buffer_consume_end(&incoming_packet, 4); 973 974 if (packet_compression) { 975 buffer_clear(&compression_buffer); 976 buffer_uncompress(&incoming_packet, &compression_buffer); 977 buffer_clear(&incoming_packet); 978 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 979 buffer_len(&compression_buffer)); 980 } 981 type = buffer_get_char(&incoming_packet); 982 return type; 983 } 984 985 static int 986 packet_read_poll2(u_int32_t *seqnr_p) 987 { 988 static u_int packet_length = 0; 989 u_int padlen, need; 990 u_char *macbuf, *cp, type; 991 int maclen, block_size; 992 Enc *enc = NULL; 993 Mac *mac = NULL; 994 Comp *comp = NULL; 995 996 if (newkeys[MODE_IN] != NULL) { 997 enc = &newkeys[MODE_IN]->enc; 998 mac = &newkeys[MODE_IN]->mac; 999 comp = &newkeys[MODE_IN]->comp; 1000 } 1001 maclen = mac && mac->enabled ? mac->mac_len : 0; 1002 block_size = enc ? enc->block_size : 8; 1003 1004 if (packet_length == 0) { 1005 /* 1006 * check if input size is less than the cipher block size, 1007 * decrypt first block and extract length of incoming packet 1008 */ 1009 if (buffer_len(&input) < block_size) 1010 return SSH_MSG_NONE; 1011 buffer_clear(&incoming_packet); 1012 cp = buffer_append_space(&incoming_packet, block_size); 1013 cipher_crypt(&receive_context, cp, buffer_ptr(&input), 1014 block_size); 1015 cp = buffer_ptr(&incoming_packet); 1016 packet_length = GET_32BIT(cp); 1017 if (packet_length < 1 + 4 || packet_length > 256 * 1024) { 1018 buffer_dump(&incoming_packet); 1019 packet_disconnect("Bad packet length %u.", packet_length); 1020 } 1021 DBG(debug("input: packet len %u", packet_length+4)); 1022 buffer_consume(&input, block_size); 1023 } 1024 /* we have a partial packet of block_size bytes */ 1025 need = 4 + packet_length - block_size; 1026 DBG(debug("partial packet %d, need %d, maclen %d", block_size, 1027 need, maclen)); 1028 if (need % block_size != 0) 1029 fatal("padding error: need %d block %d mod %d", 1030 need, block_size, need % block_size); 1031 /* 1032 * check if the entire packet has been received and 1033 * decrypt into incoming_packet 1034 */ 1035 if (buffer_len(&input) < need + maclen) 1036 return SSH_MSG_NONE; 1037 #ifdef PACKET_DEBUG 1038 fprintf(stderr, "read_poll enc/full: "); 1039 buffer_dump(&input); 1040 #endif 1041 cp = buffer_append_space(&incoming_packet, need); 1042 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); 1043 buffer_consume(&input, need); 1044 /* 1045 * compute MAC over seqnr and packet, 1046 * increment sequence number for incoming packet 1047 */ 1048 if (mac && mac->enabled) { 1049 macbuf = mac_compute(mac, p_read.seqnr, 1050 buffer_ptr(&incoming_packet), 1051 buffer_len(&incoming_packet)); 1052 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) 1053 packet_disconnect("Corrupted MAC on input."); 1054 DBG(debug("MAC #%d ok", p_read.seqnr)); 1055 buffer_consume(&input, mac->mac_len); 1056 } 1057 if (seqnr_p != NULL) 1058 *seqnr_p = p_read.seqnr; 1059 if (++p_read.seqnr == 0) 1060 logit("incoming seqnr wraps around"); 1061 if (++p_read.packets == 0) 1062 if (!(datafellows & SSH_BUG_NOREKEY)) 1063 fatal("XXX too many packets with same key"); 1064 p_read.blocks += (packet_length + 4) / block_size; 1065 1066 /* get padlen */ 1067 cp = buffer_ptr(&incoming_packet); 1068 padlen = cp[4]; 1069 DBG(debug("input: padlen %d", padlen)); 1070 if (padlen < 4) 1071 packet_disconnect("Corrupted padlen %d on input.", padlen); 1072 1073 /* skip packet size + padlen, discard padding */ 1074 buffer_consume(&incoming_packet, 4 + 1); 1075 buffer_consume_end(&incoming_packet, padlen); 1076 1077 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); 1078 if (comp && comp->enabled) { 1079 buffer_clear(&compression_buffer); 1080 buffer_uncompress(&incoming_packet, &compression_buffer); 1081 buffer_clear(&incoming_packet); 1082 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), 1083 buffer_len(&compression_buffer)); 1084 DBG(debug("input: len after de-compress %d", 1085 buffer_len(&incoming_packet))); 1086 } 1087 /* 1088 * get packet type, implies consume. 1089 * return length of payload (without type field) 1090 */ 1091 type = buffer_get_char(&incoming_packet); 1092 if (type == SSH2_MSG_NEWKEYS) 1093 set_newkeys(MODE_IN); 1094 #ifdef PACKET_DEBUG 1095 fprintf(stderr, "read/plain[%d]:\r\n", type); 1096 buffer_dump(&incoming_packet); 1097 #endif 1098 /* reset for next packet */ 1099 packet_length = 0; 1100 return type; 1101 } 1102 1103 int 1104 packet_read_poll_seqnr(u_int32_t *seqnr_p) 1105 { 1106 u_int reason, seqnr; 1107 u_char type; 1108 char *msg; 1109 1110 for (;;) { 1111 if (compat20) { 1112 type = packet_read_poll2(seqnr_p); 1113 if (type) 1114 DBG(debug("received packet type %d", type)); 1115 switch (type) { 1116 case SSH2_MSG_IGNORE: 1117 break; 1118 case SSH2_MSG_DEBUG: 1119 packet_get_char(); 1120 msg = packet_get_string(NULL); 1121 debug("Remote: %.900s", msg); 1122 xfree(msg); 1123 msg = packet_get_string(NULL); 1124 xfree(msg); 1125 break; 1126 case SSH2_MSG_DISCONNECT: 1127 reason = packet_get_int(); 1128 msg = packet_get_string(NULL); 1129 logit("Received disconnect from %s: %u: %.400s", 1130 get_remote_ipaddr(), reason, msg); 1131 xfree(msg); 1132 fatal_cleanup(); 1133 break; 1134 case SSH2_MSG_UNIMPLEMENTED: 1135 seqnr = packet_get_int(); 1136 debug("Received SSH2_MSG_UNIMPLEMENTED for %u", 1137 seqnr); 1138 break; 1139 default: 1140 return type; 1141 break; 1142 } 1143 } else { 1144 type = packet_read_poll1(); 1145 switch (type) { 1146 case SSH_MSG_IGNORE: 1147 break; 1148 case SSH_MSG_DEBUG: 1149 msg = packet_get_string(NULL); 1150 debug("Remote: %.900s", msg); 1151 xfree(msg); 1152 break; 1153 case SSH_MSG_DISCONNECT: 1154 msg = packet_get_string(NULL); 1155 logit("Received disconnect from %s: %.400s", 1156 get_remote_ipaddr(), msg); 1157 fatal_cleanup(); 1158 xfree(msg); 1159 break; 1160 default: 1161 if (type) 1162 DBG(debug("received packet type %d", type)); 1163 return type; 1164 break; 1165 } 1166 } 1167 } 1168 } 1169 1170 int 1171 packet_read_poll(void) 1172 { 1173 return packet_read_poll_seqnr(NULL); 1174 } 1175 1176 /* 1177 * Buffers the given amount of input characters. This is intended to be used 1178 * together with packet_read_poll. 1179 */ 1180 1181 void 1182 packet_process_incoming(const char *buf, u_int len) 1183 { 1184 buffer_append(&input, buf, len); 1185 } 1186 1187 /* Returns a character from the packet. */ 1188 1189 u_int 1190 packet_get_char(void) 1191 { 1192 char ch; 1193 1194 buffer_get(&incoming_packet, &ch, 1); 1195 return (u_char) ch; 1196 } 1197 1198 /* Returns an integer from the packet data. */ 1199 1200 u_int 1201 packet_get_int(void) 1202 { 1203 return buffer_get_int(&incoming_packet); 1204 } 1205 1206 /* 1207 * Returns an arbitrary precision integer from the packet data. The integer 1208 * must have been initialized before this call. 1209 */ 1210 1211 void 1212 packet_get_bignum(BIGNUM * value) 1213 { 1214 buffer_get_bignum(&incoming_packet, value); 1215 } 1216 1217 void 1218 packet_get_bignum2(BIGNUM * value) 1219 { 1220 buffer_get_bignum2(&incoming_packet, value); 1221 } 1222 1223 void * 1224 packet_get_raw(int *length_ptr) 1225 { 1226 int bytes = buffer_len(&incoming_packet); 1227 1228 if (length_ptr != NULL) 1229 *length_ptr = bytes; 1230 return buffer_ptr(&incoming_packet); 1231 } 1232 1233 int 1234 packet_remaining(void) 1235 { 1236 return buffer_len(&incoming_packet); 1237 } 1238 1239 /* 1240 * Returns a string from the packet data. The string is allocated using 1241 * xmalloc; it is the responsibility of the calling program to free it when 1242 * no longer needed. The length_ptr argument may be NULL, or point to an 1243 * integer into which the length of the string is stored. 1244 */ 1245 1246 void * 1247 packet_get_string(u_int *length_ptr) 1248 { 1249 return buffer_get_string(&incoming_packet, length_ptr); 1250 } 1251 1252 /* 1253 * Sends a diagnostic message from the server to the client. This message 1254 * can be sent at any time (but not while constructing another message). The 1255 * message is printed immediately, but only if the client is being executed 1256 * in verbose mode. These messages are primarily intended to ease debugging 1257 * authentication problems. The length of the formatted message must not 1258 * exceed 1024 bytes. This will automatically call packet_write_wait. 1259 */ 1260 1261 void 1262 packet_send_debug(const char *fmt,...) 1263 { 1264 char buf[1024]; 1265 va_list args; 1266 1267 if (compat20 && (datafellows & SSH_BUG_DEBUG)) 1268 return; 1269 1270 va_start(args, fmt); 1271 vsnprintf(buf, sizeof(buf), fmt, args); 1272 va_end(args); 1273 1274 if (compat20) { 1275 packet_start(SSH2_MSG_DEBUG); 1276 packet_put_char(0); /* bool: always display */ 1277 packet_put_cstring(buf); 1278 packet_put_cstring(""); 1279 } else { 1280 packet_start(SSH_MSG_DEBUG); 1281 packet_put_cstring(buf); 1282 } 1283 packet_send(); 1284 packet_write_wait(); 1285 } 1286 1287 /* 1288 * Logs the error plus constructs and sends a disconnect packet, closes the 1289 * connection, and exits. This function never returns. The error message 1290 * should not contain a newline. The length of the formatted message must 1291 * not exceed 1024 bytes. 1292 */ 1293 1294 void 1295 packet_disconnect(const char *fmt,...) 1296 { 1297 char buf[1024]; 1298 va_list args; 1299 static int disconnecting = 0; 1300 1301 if (disconnecting) /* Guard against recursive invocations. */ 1302 fatal("packet_disconnect called recursively."); 1303 disconnecting = 1; 1304 1305 /* 1306 * Format the message. Note that the caller must make sure the 1307 * message is of limited size. 1308 */ 1309 va_start(args, fmt); 1310 vsnprintf(buf, sizeof(buf), fmt, args); 1311 va_end(args); 1312 1313 /* Display the error locally */ 1314 logit("Disconnecting: %.100s", buf); 1315 1316 /* Send the disconnect message to the other side, and wait for it to get sent. */ 1317 if (compat20) { 1318 packet_start(SSH2_MSG_DISCONNECT); 1319 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); 1320 packet_put_cstring(buf); 1321 packet_put_cstring(""); 1322 } else { 1323 packet_start(SSH_MSG_DISCONNECT); 1324 packet_put_cstring(buf); 1325 } 1326 packet_send(); 1327 packet_write_wait(); 1328 1329 /* Stop listening for connections. */ 1330 channel_close_all(); 1331 1332 /* Close the connection. */ 1333 packet_close(); 1334 1335 fatal_cleanup(); 1336 } 1337 1338 /* Checks if there is any buffered output, and tries to write some of the output. */ 1339 1340 void 1341 packet_write_poll(void) 1342 { 1343 int len = buffer_len(&output); 1344 1345 if (len > 0) { 1346 len = write(connection_out, buffer_ptr(&output), len); 1347 if (len <= 0) { 1348 if (errno == EAGAIN) 1349 return; 1350 else 1351 fatal("Write failed: %.100s", strerror(errno)); 1352 } 1353 buffer_consume(&output, len); 1354 } 1355 } 1356 1357 /* 1358 * Calls packet_write_poll repeatedly until all pending output data has been 1359 * written. 1360 */ 1361 1362 void 1363 packet_write_wait(void) 1364 { 1365 fd_set *setp; 1366 1367 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * 1368 sizeof(fd_mask)); 1369 packet_write_poll(); 1370 while (packet_have_data_to_write()) { 1371 memset(setp, 0, howmany(connection_out + 1, NFDBITS) * 1372 sizeof(fd_mask)); 1373 FD_SET(connection_out, setp); 1374 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && 1375 (errno == EAGAIN || errno == EINTR)) 1376 ; 1377 packet_write_poll(); 1378 } 1379 xfree(setp); 1380 } 1381 1382 /* Returns true if there is buffered data to write to the connection. */ 1383 1384 int 1385 packet_have_data_to_write(void) 1386 { 1387 return buffer_len(&output) != 0; 1388 } 1389 1390 /* Returns true if there is not too much data to write to the connection. */ 1391 1392 int 1393 packet_not_very_much_data_to_write(void) 1394 { 1395 if (interactive_mode) 1396 return buffer_len(&output) < 16384; 1397 else 1398 return buffer_len(&output) < 128 * 1024; 1399 } 1400 1401 static void 1402 packet_set_tos(int interactive) 1403 { 1404 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; 1405 1406 if (!packet_connection_is_on_socket() || 1407 !packet_connection_is_ipv4()) 1408 return; 1409 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos, 1410 sizeof(tos)) < 0) 1411 error("setsockopt IP_TOS %d: %.100s:", 1412 tos, strerror(errno)); 1413 } 1414 1415 /* Informs that the current session is interactive. Sets IP flags for that. */ 1416 1417 void 1418 packet_set_interactive(int interactive) 1419 { 1420 static int called = 0; 1421 1422 if (called) 1423 return; 1424 called = 1; 1425 1426 /* Record that we are in interactive mode. */ 1427 interactive_mode = interactive; 1428 1429 /* Only set socket options if using a socket. */ 1430 if (!packet_connection_is_on_socket()) 1431 return; 1432 if (interactive) 1433 set_nodelay(connection_in); 1434 packet_set_tos(interactive); 1435 } 1436 1437 /* Returns true if the current connection is interactive. */ 1438 1439 int 1440 packet_is_interactive(void) 1441 { 1442 return interactive_mode; 1443 } 1444 1445 u_int 1446 packet_set_maxsize(u_int s) 1447 { 1448 static int called = 0; 1449 1450 if (called) { 1451 logit("packet_set_maxsize: called twice: old %d new %d", 1452 max_packet_size, s); 1453 return -1; 1454 } 1455 if (s < 4 * 1024 || s > 1024 * 1024) { 1456 logit("packet_set_maxsize: bad size %d", s); 1457 return -1; 1458 } 1459 called = 1; 1460 debug("packet_set_maxsize: setting to %d", s); 1461 max_packet_size = s; 1462 return s; 1463 } 1464 1465 /* roundup current message to pad bytes */ 1466 void 1467 packet_add_padding(u_char pad) 1468 { 1469 extra_pad = pad; 1470 } 1471 1472 /* 1473 * 9.2. Ignored Data Message 1474 * 1475 * byte SSH_MSG_IGNORE 1476 * string data 1477 * 1478 * All implementations MUST understand (and ignore) this message at any 1479 * time (after receiving the protocol version). No implementation is 1480 * required to send them. This message can be used as an additional 1481 * protection measure against advanced traffic analysis techniques. 1482 */ 1483 void 1484 packet_send_ignore(int nbytes) 1485 { 1486 u_int32_t rand = 0; 1487 int i; 1488 1489 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); 1490 packet_put_int(nbytes); 1491 for (i = 0; i < nbytes; i++) { 1492 if (i % 4 == 0) 1493 rand = arc4random(); 1494 packet_put_char(rand & 0xff); 1495 rand >>= 8; 1496 } 1497 } 1498 1499 #define MAX_PACKETS (1<<31) 1500 int 1501 packet_need_rekeying(void) 1502 { 1503 if (datafellows & SSH_BUG_NOREKEY) 1504 return 0; 1505 return 1506 (p_send.packets > MAX_PACKETS) || 1507 (p_read.packets > MAX_PACKETS) || 1508 (max_blocks_out && (p_send.blocks > max_blocks_out)) || 1509 (max_blocks_in && (p_read.blocks > max_blocks_in)); 1510 } 1511 1512 void 1513 packet_set_rekey_limit(u_int32_t bytes) 1514 { 1515 rekey_limit = bytes; 1516 } 1517