packet.c

   1 /* $OpenBSD: packet.c,v 1.158 2008/11/21 15:47:38 markus Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file contains code implementing the packet protocol and communication
   7  * with the other side.  This same code is used both on client and server side.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  *
  16  * SSH2 packet format added by Markus Friedl.
  17  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  18  *
  19  * Redistribution and use in source and binary forms, with or without
  20  * modification, are permitted provided that the following conditions
  21  * are met:
  22  * 1. Redistributions of source code must retain the above copyright
  23  *    notice, this list of conditions and the following disclaimer.
  24  * 2. Redistributions in binary form must reproduce the above copyright
  25  *    notice, this list of conditions and the following disclaimer in the
  26  *    documentation and/or other materials provided with the distribution.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  29  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  30  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  31  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  32  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  33  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  37  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  38  */
  39
  40 #include "includes.h"
  41
  42 #include <sys/types.h>
  43 #include "openbsd-compat/sys-queue.h"
  44 #include <sys/param.h>
  45 #include <sys/socket.h>
  46 #ifdef HAVE_SYS_TIME_H
  47 # include <sys/time.h>
  48 #endif
  49
  50 #include <netinet/in.h>
  51 #include <netinet/ip.h>
  52 #include <arpa/inet.h>
  53
  54 #include <errno.h>
  55 #include <stdarg.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60 #include <signal.h>
  61
  62 #include "xmalloc.h"
  63 #include "buffer.h"
  64 #include "packet.h"
  65 #include "crc32.h"
  66 #include "compress.h"
  67 #include "deattack.h"
  68 #include "channels.h"
  69 #include "compat.h"
  70 #include "ssh1.h"
  71 #include "ssh2.h"
  72 #include "cipher.h"
  73 #include "key.h"
  74 #include "kex.h"
  75 #include "mac.h"
  76 #include "log.h"
  77 #include "canohost.h"
  78 #include "misc.h"
  79 #include "ssh.h"
  80
  81 #ifdef PACKET_DEBUG
  82 #define DBG(x) x
  83 #else
  84 #define DBG(x)
  85 #endif
  86
  87 /*
  88  * This variable contains the file descriptors used for communicating with
  89  * the other side.  connection_in is used for reading; connection_out for
  90  * writing.  These can be the same descriptor, in which case it is assumed to
  91  * be a socket.
  92  */
  93 static int connection_in = -1;
  94 static int connection_out = -1;
  95
  96 /* Protocol flags for the remote side. */
  97 static u_int remote_protocol_flags = 0;
  98
  99 /* Encryption context for receiving data.  This is only used for decryption. */
 100 static CipherContext receive_context;
 101
 102 /* Encryption context for sending data.  This is only used for encryption. */
 103 static CipherContext send_context;
 104
 105 /* Buffer for raw input data from the socket. */
 106 Buffer input;
 107
 108 /* Buffer for raw output data going to the socket. */
 109 Buffer output;
 110
 111 /* Buffer for the partial outgoing packet being constructed. */
 112 static Buffer outgoing_packet;
 113
 114 /* Buffer for the incoming packet currently being processed. */
 115 static Buffer incoming_packet;
 116
 117 /* Scratch buffer for packet compression/decompression. */
 118 static Buffer compression_buffer;
 119 static int compression_buffer_ready = 0;
 120
 121 /* Flag indicating whether packet compression/decompression is enabled. */
 122 static int packet_compression = 0;
 123
 124 /* default maximum packet size */
 125 u_int max_packet_size = 32768;
 126
 127 /* Flag indicating whether this module has been initialized. */
 128 static int initialized = 0;
 129
 130 /* Set to true if the connection is interactive. */
 131 static int interactive_mode = 0;
 132
 133 /* Set to true if we are the server side. */
 134 static int server_side = 0;
 135
 136 /* Set to true if we are authenticated. */
 137 static int after_authentication = 0;
 138
 139 int keep_alive_timeouts = 0;
 140
 141 /* Set to the maximum time that we will wait to send or receive a packet */
 142 static int packet_timeout_ms = -1;
 143
 144 /* Session key information for Encryption and MAC */
 145 Newkeys *newkeys[MODE_MAX];
 146 static struct packet_state {
 147         u_int32_t seqnr;
 148         u_int32_t packets;
 149         u_int64_t blocks;
 150         u_int64_t bytes;
 151 } p_read, p_send;
 152
 153 static u_int64_t max_blocks_in, max_blocks_out;
 154 static u_int32_t rekey_limit;
 155
 156 /* Session key for protocol v1 */
 157 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 158 static u_int ssh1_keylen;
 159
 160 /* roundup current message to extra_pad bytes */
 161 static u_char extra_pad = 0;
 162
 163 struct packet {
 164         TAILQ_ENTRY(packet) next;
 165         u_char type;
 166         Buffer payload;
 167 };
 168 TAILQ_HEAD(, packet) outgoing;
 169
 170 /*
 171  * Sets the descriptors used for communication.  Disables encryption until
 172  * packet_set_encryption_key is called.
 173  */
 174 void
 175 packet_set_connection(int fd_in, int fd_out)
 176 {
 177         Cipher *none = cipher_by_name("none");
 178
 179         if (none == NULL)
 180                 fatal("packet_set_connection: cannot load cipher 'none'");
 181         connection_in = fd_in;
 182         connection_out = fd_out;
 183         cipher_init(&send_context, none, (const u_char *)"",
 184             0, NULL, 0, CIPHER_ENCRYPT);
 185         cipher_init(&receive_context, none, (const u_char *)"",
 186             0, NULL, 0, CIPHER_DECRYPT);
 187         newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
 188         if (!initialized) {
 189                 initialized = 1;
 190                 buffer_init(&input);
 191                 buffer_init(&output);
 192                 buffer_init(&outgoing_packet);
 193                 buffer_init(&incoming_packet);
 194                 TAILQ_INIT(&outgoing);
 195                 p_send.packets = p_read.packets = 0;
 196         }
 197 }
 198
 199 void
 200 packet_set_timeout(int timeout, int count)
 201 {
 202         if (timeout == 0 || count == 0) {
 203                 packet_timeout_ms = -1;
 204                 return;
 205         }
 206         if ((INT_MAX / 1000) / count < timeout)
 207                 packet_timeout_ms = INT_MAX;
 208         else
 209                 packet_timeout_ms = timeout * count * 1000;
 210 }
 211
 212 /* Returns 1 if remote host is connected via socket, 0 if not. */
 213
 214 int
 215 packet_connection_is_on_socket(void)
 216 {
 217         struct sockaddr_storage from, to;
 218         socklen_t fromlen, tolen;
 219
 220         /* filedescriptors in and out are the same, so it's a socket */
 221         if (connection_in == connection_out)
 222                 return 1;
 223         fromlen = sizeof(from);
 224         memset(&from, 0, sizeof(from));
 225         if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
 226                 return 0;
 227         tolen = sizeof(to);
 228         memset(&to, 0, sizeof(to));
 229         if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
 230                 return 0;
 231         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 232                 return 0;
 233         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 234                 return 0;
 235         return 1;
 236 }
 237
 238 /*
 239  * Exports an IV from the CipherContext required to export the key
 240  * state back from the unprivileged child to the privileged parent
 241  * process.
 242  */
 243
 244 void
 245 packet_get_keyiv(int mode, u_char *iv, u_int len)
 246 {
 247         CipherContext *cc;
 248
 249         if (mode == MODE_OUT)
 250                 cc = &send_context;
 251         else
 252                 cc = &receive_context;
 253
 254         cipher_get_keyiv(cc, iv, len);
 255 }
 256
 257 int
 258 packet_get_keycontext(int mode, u_char *dat)
 259 {
 260         CipherContext *cc;
 261
 262         if (mode == MODE_OUT)
 263                 cc = &send_context;
 264         else
 265                 cc = &receive_context;
 266
 267         return (cipher_get_keycontext(cc, dat));
 268 }
 269
 270 void
 271 packet_set_keycontext(int mode, u_char *dat)
 272 {
 273         CipherContext *cc;
 274
 275         if (mode == MODE_OUT)
 276                 cc = &send_context;
 277         else
 278                 cc = &receive_context;
 279
 280         cipher_set_keycontext(cc, dat);
 281 }
 282
 283 int
 284 packet_get_keyiv_len(int mode)
 285 {
 286         CipherContext *cc;
 287
 288         if (mode == MODE_OUT)
 289                 cc = &send_context;
 290         else
 291                 cc = &receive_context;
 292
 293         return (cipher_get_keyiv_len(cc));
 294 }
 295
 296 void
 297 packet_set_iv(int mode, u_char *dat)
 298 {
 299         CipherContext *cc;
 300
 301         if (mode == MODE_OUT)
 302                 cc = &send_context;
 303         else
 304                 cc = &receive_context;
 305
 306         cipher_set_keyiv(cc, dat);
 307 }
 308
 309 int
 310 packet_get_ssh1_cipher(void)
 311 {
 312         return (cipher_get_number(receive_context.cipher));
 313 }
 314
 315 void
 316 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets,
 317     u_int64_t *bytes)
 318 {
 319         struct packet_state *state;
 320
 321         state = (mode == MODE_IN) ? &p_read : &p_send;
 322         if (seqnr)
 323                 *seqnr = state->seqnr;
 324         if (blocks)
 325                 *blocks = state->blocks;
 326         if (packets)
 327                 *packets = state->packets;
 328         if (bytes)
 329                 *bytes = state->bytes;
 330 }
 331
 332 void
 333 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
 334     u_int64_t bytes)
 335 {
 336         struct packet_state *state;
 337
 338         state = (mode == MODE_IN) ? &p_read : &p_send;
 339         state->seqnr = seqnr;
 340         state->blocks = blocks;
 341         state->packets = packets;
 342         state->bytes = bytes;
 343 }
 344
 345 /* returns 1 if connection is via ipv4 */
 346
 347 int
 348 packet_connection_is_ipv4(void)
 349 {
 350         struct sockaddr_storage to;
 351         socklen_t tolen = sizeof(to);
 352
 353         memset(&to, 0, sizeof(to));
 354         if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
 355                 return 0;
 356         if (to.ss_family == AF_INET)
 357                 return 1;
 358 #ifdef IPV4_IN_IPV6
 359         if (to.ss_family == AF_INET6 &&
 360             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 361                 return 1;
 362 #endif
 363         return 0;
 364 }
 365
 366 /* Sets the connection into non-blocking mode. */
 367
 368 void
 369 packet_set_nonblocking(void)
 370 {
 371         /* Set the socket into non-blocking mode. */
 372         set_nonblock(connection_in);
 373
 374         if (connection_out != connection_in)
 375                 set_nonblock(connection_out);
 376 }
 377
 378 /* Returns the socket used for reading. */
 379
 380 int
 381 packet_get_connection_in(void)
 382 {
 383         return connection_in;
 384 }
 385
 386 /* Returns the descriptor used for writing. */
 387
 388 int
 389 packet_get_connection_out(void)
 390 {
 391         return connection_out;
 392 }
 393
 394 /* Closes the connection and clears and frees internal data structures. */
 395
 396 void
 397 packet_close(void)
 398 {
 399         if (!initialized)
 400                 return;
 401         initialized = 0;
 402         if (connection_in == connection_out) {
 403                 shutdown(connection_out, SHUT_RDWR);
 404                 close(connection_out);
 405         } else {
 406                 close(connection_in);
 407                 close(connection_out);
 408         }
 409         buffer_free(&input);
 410         buffer_free(&output);
 411         buffer_free(&outgoing_packet);
 412         buffer_free(&incoming_packet);
 413         if (compression_buffer_ready) {
 414                 buffer_free(&compression_buffer);
 415                 buffer_compress_uninit();
 416         }
 417         cipher_cleanup(&send_context);
 418         cipher_cleanup(&receive_context);
 419 }
 420
 421 /* Sets remote side protocol flags. */
 422
 423 void
 424 packet_set_protocol_flags(u_int protocol_flags)
 425 {
 426         remote_protocol_flags = protocol_flags;
 427 }
 428
 429 /* Returns the remote protocol flags set earlier by the above function. */
 430
 431 u_int
 432 packet_get_protocol_flags(void)
 433 {
 434         return remote_protocol_flags;
 435 }
 436
 437 /*
 438  * Starts packet compression from the next packet on in both directions.
 439  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 440  */
 441
 442 static void
 443 packet_init_compression(void)
 444 {
 445         if (compression_buffer_ready == 1)
 446                 return;
 447         compression_buffer_ready = 1;
 448         buffer_init(&compression_buffer);
 449 }
 450
 451 void
 452 packet_start_compression(int level)
 453 {
 454         if (packet_compression && !compat20)
 455                 fatal("Compression already enabled.");
 456         packet_compression = 1;
 457         packet_init_compression();
 458         buffer_compress_init_send(level);
 459         buffer_compress_init_recv();
 460 }
 461
 462 /*
 463  * Causes any further packets to be encrypted using the given key.  The same
 464  * key is used for both sending and reception.  However, both directions are
 465  * encrypted independently of each other.
 466  */
 467
 468 void
 469 packet_set_encryption_key(const u_char *key, u_int keylen,
 470     int number)
 471 {
 472         Cipher *cipher = cipher_by_number(number);
 473
 474         if (cipher == NULL)
 475                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 476         if (keylen < 20)
 477                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 478         if (keylen > SSH_SESSION_KEY_LENGTH)
 479                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 480         memcpy(ssh1_key, key, keylen);
 481         ssh1_keylen = keylen;
 482         cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
 483         cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
 484 }
 485
 486 u_int
 487 packet_get_encryption_key(u_char *key)
 488 {
 489         if (key == NULL)
 490                 return (ssh1_keylen);
 491         memcpy(key, ssh1_key, ssh1_keylen);
 492         return (ssh1_keylen);
 493 }
 494
 495 /* Start constructing a packet to send. */
 496 void
 497 packet_start(u_char type)
 498 {
 499         u_char buf[9];
 500         int len;
 501
 502         DBG(debug("packet_start[%d]", type));
 503         len = compat20 ? 6 : 9;
 504         memset(buf, 0, len - 1);
 505         buf[len - 1] = type;
 506         buffer_clear(&outgoing_packet);
 507         buffer_append(&outgoing_packet, buf, len);
 508 }
 509
 510 /* Append payload. */
 511 void
 512 packet_put_char(int value)
 513 {
 514         char ch = value;
 515
 516         buffer_append(&outgoing_packet, &ch, 1);
 517 }
 518
 519 void
 520 packet_put_int(u_int value)
 521 {
 522         buffer_put_int(&outgoing_packet, value);
 523 }
 524
 525 void
 526 packet_put_string(const void *buf, u_int len)
 527 {
 528         buffer_put_string(&outgoing_packet, buf, len);
 529 }
 530
 531 void
 532 packet_put_cstring(const char *str)
 533 {
 534         buffer_put_cstring(&outgoing_packet, str);
 535 }
 536
 537 void
 538 packet_put_raw(const void *buf, u_int len)
 539 {
 540         buffer_append(&outgoing_packet, buf, len);
 541 }
 542
 543 void
 544 packet_put_bignum(BIGNUM * value)
 545 {
 546         buffer_put_bignum(&outgoing_packet, value);
 547 }
 548
 549 void
 550 packet_put_bignum2(BIGNUM * value)
 551 {
 552         buffer_put_bignum2(&outgoing_packet, value);
 553 }
 554
 555 /*
 556  * Finalizes and sends the packet.  If the encryption key has been set,
 557  * encrypts the packet before sending.
 558  */
 559
 560 static void
 561 packet_send1(void)
 562 {
 563         u_char buf[8], *cp;
 564         int i, padding, len;
 565         u_int checksum;
 566         u_int32_t rnd = 0;
 567
 568         /*
 569          * If using packet compression, compress the payload of the outgoing
 570          * packet.
 571          */
 572         if (packet_compression) {
 573                 buffer_clear(&compression_buffer);
 574                 /* Skip padding. */
 575                 buffer_consume(&outgoing_packet, 8);
 576                 /* padding */
 577                 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
 578                 buffer_compress(&outgoing_packet, &compression_buffer);
 579                 buffer_clear(&outgoing_packet);
 580                 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
 581                     buffer_len(&compression_buffer));
 582         }
 583         /* Compute packet length without padding (add checksum, remove padding). */
 584         len = buffer_len(&outgoing_packet) + 4 - 8;
 585
 586         /* Insert padding. Initialized to zero in packet_start1() */
 587         padding = 8 - len % 8;
 588         if (!send_context.plaintext) {
 589                 cp = buffer_ptr(&outgoing_packet);
 590                 for (i = 0; i < padding; i++) {
 591                         if (i % 4 == 0)
 592                                 rnd = arc4random();
 593                         cp[7 - i] = rnd & 0xff;
 594                         rnd >>= 8;
 595                 }
 596         }
 597         buffer_consume(&outgoing_packet, 8 - padding);
 598
 599         /* Add check bytes. */
 600         checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
 601             buffer_len(&outgoing_packet));
 602         put_u32(buf, checksum);
 603         buffer_append(&outgoing_packet, buf, 4);
 604
 605 #ifdef PACKET_DEBUG
 606         fprintf(stderr, "packet_send plain: ");
 607         buffer_dump(&outgoing_packet);
 608 #endif
 609
 610         /* Append to output. */
 611         put_u32(buf, len);
 612         buffer_append(&output, buf, 4);
 613         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
 614         cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
 615             buffer_len(&outgoing_packet));
 616
 617 #ifdef PACKET_DEBUG
 618         fprintf(stderr, "encrypted: ");
 619         buffer_dump(&output);
 620 #endif
 621         p_send.packets++;
 622         p_send.bytes += len + buffer_len(&outgoing_packet);
 623         buffer_clear(&outgoing_packet);
 624
 625         /*
 626          * Note that the packet is now only buffered in output.  It won't be
 627          * actually sent until packet_write_wait or packet_write_poll is
 628          * called.
 629          */
 630 }
 631
 632 void
 633 set_newkeys(int mode)
 634 {
 635         Enc *enc;
 636         Mac *mac;
 637         Comp *comp;
 638         CipherContext *cc;
 639         u_int64_t *max_blocks;
 640         int crypt_type;
 641
 642         debug2("set_newkeys: mode %d", mode);
 643
 644         if (mode == MODE_OUT) {
 645                 cc = &send_context;
 646                 crypt_type = CIPHER_ENCRYPT;
 647                 p_send.packets = p_send.blocks = 0;
 648                 max_blocks = &max_blocks_out;
 649         } else {
 650                 cc = &receive_context;
 651                 crypt_type = CIPHER_DECRYPT;
 652                 p_read.packets = p_read.blocks = 0;
 653                 max_blocks = &max_blocks_in;
 654         }
 655         if (newkeys[mode] != NULL) {
 656                 debug("set_newkeys: rekeying");
 657                 cipher_cleanup(cc);
 658                 enc  = &newkeys[mode]->enc;
 659                 mac  = &newkeys[mode]->mac;
 660                 comp = &newkeys[mode]->comp;
 661                 mac_clear(mac);
 662                 xfree(enc->name);
 663                 xfree(enc->iv);
 664                 xfree(enc->key);
 665                 xfree(mac->name);
 666                 xfree(mac->key);
 667                 xfree(comp->name);
 668                 xfree(newkeys[mode]);
 669         }
 670         newkeys[mode] = kex_get_newkeys(mode);
 671         if (newkeys[mode] == NULL)
 672                 fatal("newkeys: no keys for mode %d", mode);
 673         enc  = &newkeys[mode]->enc;
 674         mac  = &newkeys[mode]->mac;
 675         comp = &newkeys[mode]->comp;
 676         if (mac_init(mac) == 0)
 677                 mac->enabled = 1;
 678         DBG(debug("cipher_init_context: %d", mode));
 679         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 680             enc->iv, enc->block_size, crypt_type);
 681         /* Deleting the keys does not gain extra security */
 682         /* memset(enc->iv,  0, enc->block_size);
 683            memset(enc->key, 0, enc->key_len);
 684            memset(mac->key, 0, mac->key_len); */
 685         if ((comp->type == COMP_ZLIB ||
 686             (comp->type == COMP_DELAYED && after_authentication)) &&
 687             comp->enabled == 0) {
 688                 packet_init_compression();
 689                 if (mode == MODE_OUT)
 690                         buffer_compress_init_send(6);
 691                 else
 692                         buffer_compress_init_recv();
 693                 comp->enabled = 1;
 694         }
 695         /*
 696          * The 2^(blocksize*2) limit is too expensive for 3DES,
 697          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 698          */
 699         if (enc->block_size >= 16)
 700                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 701         else
 702                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 703         if (rekey_limit)
 704                 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
 705 }
 706
 707 /*
 708  * Delayed compression for SSH2 is enabled after authentication:
 709  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 710  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 711  */
 712 static void
 713 packet_enable_delayed_compress(void)
 714 {
 715         Comp *comp = NULL;
 716         int mode;
 717
 718         /*
 719          * Remember that we are past the authentication step, so rekeying
 720          * with COMP_DELAYED will turn on compression immediately.
 721          */
 722         after_authentication = 1;
 723         for (mode = 0; mode < MODE_MAX; mode++) {
 724                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 725                 if (newkeys[mode] == NULL)
 726                         continue;
 727                 comp = &newkeys[mode]->comp;
 728                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 729                         packet_init_compression();
 730                         if (mode == MODE_OUT)
 731                                 buffer_compress_init_send(6);
 732                         else
 733                                 buffer_compress_init_recv();
 734                         comp->enabled = 1;
 735                 }
 736         }
 737 }
 738
 739 /*
 740  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 741  */
 742 static void
 743 packet_send2_wrapped(void)
 744 {
 745         u_char type, *cp, *macbuf = NULL;
 746         u_char padlen, pad;
 747         u_int packet_length = 0;
 748         u_int i, len;
 749         u_int32_t rnd = 0;
 750         Enc *enc   = NULL;
 751         Mac *mac   = NULL;
 752         Comp *comp = NULL;
 753         int block_size;
 754
 755         if (newkeys[MODE_OUT] != NULL) {
 756                 enc  = &newkeys[MODE_OUT]->enc;
 757                 mac  = &newkeys[MODE_OUT]->mac;
 758                 comp = &newkeys[MODE_OUT]->comp;
 759         }
 760         block_size = enc ? enc->block_size : 8;
 761
 762         cp = buffer_ptr(&outgoing_packet);
 763         type = cp[5];
 764
 765 #ifdef PACKET_DEBUG
 766         fprintf(stderr, "plain:     ");
 767         buffer_dump(&outgoing_packet);
 768 #endif
 769
 770         if (comp && comp->enabled) {
 771                 len = buffer_len(&outgoing_packet);
 772                 /* skip header, compress only payload */
 773                 buffer_consume(&outgoing_packet, 5);
 774                 buffer_clear(&compression_buffer);
 775                 buffer_compress(&outgoing_packet, &compression_buffer);
 776                 buffer_clear(&outgoing_packet);
 777                 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
 778                 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
 779                     buffer_len(&compression_buffer));
 780                 DBG(debug("compression: raw %d compressed %d", len,
 781                     buffer_len(&outgoing_packet)));
 782         }
 783
 784         /* sizeof (packet_len + pad_len + payload) */
 785         len = buffer_len(&outgoing_packet);
 786
 787         /*
 788          * calc size of padding, alloc space, get random data,
 789          * minimum padding is 4 bytes
 790          */
 791         padlen = block_size - (len % block_size);
 792         if (padlen < 4)
 793                 padlen += block_size;
 794         if (extra_pad) {
 795                 /* will wrap if extra_pad+padlen > 255 */
 796                 extra_pad  = roundup(extra_pad, block_size);
 797                 pad = extra_pad - ((len + padlen) % extra_pad);
 798                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 799                     pad, len, padlen, extra_pad);
 800                 padlen += pad;
 801                 extra_pad = 0;
 802         }
 803         cp = buffer_append_space(&outgoing_packet, padlen);
 804         if (enc && !send_context.plaintext) {
 805                 /* random padding */
 806                 for (i = 0; i < padlen; i++) {
 807                         if (i % 4 == 0)
 808                                 rnd = arc4random();
 809                         cp[i] = rnd & 0xff;
 810                         rnd >>= 8;
 811                 }
 812         } else {
 813                 /* clear padding */
 814                 memset(cp, 0, padlen);
 815         }
 816         /* packet_length includes payload, padding and padding length field */
 817         packet_length = buffer_len(&outgoing_packet) - 4;
 818         cp = buffer_ptr(&outgoing_packet);
 819         put_u32(cp, packet_length);
 820         cp[4] = padlen;
 821         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 822
 823         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 824         if (mac && mac->enabled) {
 825                 macbuf = mac_compute(mac, p_send.seqnr,
 826                     buffer_ptr(&outgoing_packet),
 827                     buffer_len(&outgoing_packet));
 828                 DBG(debug("done calc MAC out #%d", p_send.seqnr));
 829         }
 830         /* encrypt packet and append to output buffer. */
 831         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
 832         cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
 833             buffer_len(&outgoing_packet));
 834         /* append unencrypted MAC */
 835         if (mac && mac->enabled)
 836                 buffer_append(&output, macbuf, mac->mac_len);
 837 #ifdef PACKET_DEBUG
 838         fprintf(stderr, "encrypted: ");
 839         buffer_dump(&output);
 840 #endif
 841         /* increment sequence number for outgoing packets */
 842         if (++p_send.seqnr == 0)
 843                 logit("outgoing seqnr wraps around");
 844         if (++p_send.packets == 0)
 845                 if (!(datafellows & SSH_BUG_NOREKEY))
 846                         fatal("XXX too many packets with same key");
 847         p_send.blocks += (packet_length + 4) / block_size;
 848         p_send.bytes += packet_length + 4;
 849         buffer_clear(&outgoing_packet);
 850
 851         if (type == SSH2_MSG_NEWKEYS)
 852                 set_newkeys(MODE_OUT);
 853         else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
 854                 packet_enable_delayed_compress();
 855 }
 856
 857 static void
 858 packet_send2(void)
 859 {
 860         static int rekeying = 0;
 861         struct packet *p;
 862         u_char type, *cp;
 863
 864         cp = buffer_ptr(&outgoing_packet);
 865         type = cp[5];
 866
 867         /* during rekeying we can only send key exchange messages */
 868         if (rekeying) {
 869                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 870                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 871                         debug("enqueue packet: %u", type);
 872                         p = xmalloc(sizeof(*p));
 873                         p->type = type;
 874                         memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
 875                         buffer_init(&outgoing_packet);
 876                         TAILQ_INSERT_TAIL(&outgoing, p, next);
 877                         return;
 878                 }
 879         }
 880
 881         /* rekeying starts with sending KEXINIT */
 882         if (type == SSH2_MSG_KEXINIT)
 883                 rekeying = 1;
 884
 885         packet_send2_wrapped();
 886
 887         /* after a NEWKEYS message we can send the complete queue */
 888         if (type == SSH2_MSG_NEWKEYS) {
 889                 rekeying = 0;
 890                 while ((p = TAILQ_FIRST(&outgoing))) {
 891                         type = p->type;
 892                         debug("dequeue packet: %u", type);
 893                         buffer_free(&outgoing_packet);
 894                         memcpy(&outgoing_packet, &p->payload,
 895                             sizeof(Buffer));
 896                         TAILQ_REMOVE(&outgoing, p, next);
 897                         xfree(p);
 898                         packet_send2_wrapped();
 899                 }
 900         }
 901 }
 902
 903 void
 904 packet_send(void)
 905 {
 906         if (compat20)
 907                 packet_send2();
 908         else
 909                 packet_send1();
 910         DBG(debug("packet_send done"));
 911 }
 912
 913 /*
 914  * Waits until a packet has been received, and returns its type.  Note that
 915  * no other data is processed until this returns, so this function should not
 916  * be used during the interactive session.
 917  */
 918
 919 int
 920 packet_read_seqnr(u_int32_t *seqnr_p)
 921 {
 922         int type, len, ret, ms_remain;
 923         fd_set *setp;
 924         char buf[8192];
 925         struct timeval timeout, start, *timeoutp = NULL;
 926
 927         DBG(debug("packet_read()"));
 928
 929         setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
 930             sizeof(fd_mask));
 931
 932         /* Since we are blocking, ensure that all written packets have been sent. */
 933         packet_write_wait();
 934
 935         /* Stay in the loop until we have received a complete packet. */
 936         for (;;) {
 937                 /* Try to read a packet from the buffer. */
 938                 type = packet_read_poll_seqnr(seqnr_p);
 939                 if (!compat20 && (
 940                     type == SSH_SMSG_SUCCESS
 941                     || type == SSH_SMSG_FAILURE
 942                     || type == SSH_CMSG_EOF
 943                     || type == SSH_CMSG_EXIT_CONFIRMATION))
 944                         packet_check_eom();
 945                 /* If we got a packet, return it. */
 946                 if (type != SSH_MSG_NONE) {
 947                         xfree(setp);
 948                         return type;
 949                 }
 950                 /*
 951                  * Otherwise, wait for some data to arrive, add it to the
 952                  * buffer, and try again.
 953                  */
 954                 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
 955                     sizeof(fd_mask));
 956                 FD_SET(connection_in, setp);
 957
 958                 if (packet_timeout_ms > 0) {
 959                         ms_remain = packet_timeout_ms;
 960                         timeoutp = &timeout;
 961                 }
 962                 /* Wait for some data to arrive. */
 963                 for (;;) {
 964                         if (packet_timeout_ms != -1) {
 965                                 ms_to_timeval(&timeout, ms_remain);
 966                                 gettimeofday(&start, NULL);
 967                         }
 968                         if ((ret = select(connection_in + 1, setp, NULL,
 969                             NULL, timeoutp)) >= 0)
 970                                 break;
 971                         if (errno != EAGAIN && errno != EINTR &&
 972                             errno != EWOULDBLOCK)
 973                                 break;
 974                         if (packet_timeout_ms == -1)
 975                                 continue;
 976                         ms_subtract_diff(&start, &ms_remain);
 977                         if (ms_remain <= 0) {
 978                                 ret = 0;
 979                                 break;
 980                         }
 981                 }
 982                 if (ret == 0) {
 983                         logit("Connection to %.200s timed out while "
 984                             "waiting to read", get_remote_ipaddr());
 985                         cleanup_exit(255);
 986                 }
 987                 /* Read data from the socket. */
 988                 len = read(connection_in, buf, sizeof(buf));
 989                 if (len == 0) {
 990                         logit("Connection closed by %.200s", get_remote_ipaddr());
 991                         cleanup_exit(255);
 992                 }
 993                 if (len < 0)
 994                         fatal("Read from socket failed: %.100s", strerror(errno));
 995                 /* Append it to the buffer. */
 996                 packet_process_incoming(buf, len);
 997         }
 998         /* NOTREACHED */
 999 }
1000
1001 int
1002 packet_read(void)
1003 {
1004         return packet_read_seqnr(NULL);
1005 }
1006
1007 /*
1008  * Waits until a packet has been received, verifies that its type matches
1009  * that given, and gives a fatal error and exits if there is a mismatch.
1010  */
1011
1012 void
1013 packet_read_expect(int expected_type)
1014 {
1015         int type;
1016
1017         type = packet_read();
1018         if (type != expected_type)
1019                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1020                     expected_type, type);
1021 }
1022
1023 /* Checks if a full packet is available in the data received so far via
1024  * packet_process_incoming.  If so, reads the packet; otherwise returns
1025  * SSH_MSG_NONE.  This does not wait for data from the connection.
1026  *
1027  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1028  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1029  * to higher levels.
1030  */
1031
1032 static int
1033 packet_read_poll1(void)
1034 {
1035         u_int len, padded_len;
1036         u_char *cp, type;
1037         u_int checksum, stored_checksum;
1038
1039         /* Check if input size is less than minimum packet size. */
1040         if (buffer_len(&input) < 4 + 8)
1041                 return SSH_MSG_NONE;
1042         /* Get length of incoming packet. */
1043         cp = buffer_ptr(&input);
1044         len = get_u32(cp);
1045         if (len < 1 + 2 + 2 || len > 256 * 1024)
1046                 packet_disconnect("Bad packet length %u.", len);
1047         padded_len = (len + 8) & ~7;
1048
1049         /* Check if the packet has been entirely received. */
1050         if (buffer_len(&input) < 4 + padded_len)
1051                 return SSH_MSG_NONE;
1052
1053         /* The entire packet is in buffer. */
1054
1055         /* Consume packet length. */
1056         buffer_consume(&input, 4);
1057
1058         /*
1059          * Cryptographic attack detector for ssh
1060          * (C)1998 CORE-SDI, Buenos Aires Argentina
1061          * Ariel Futoransky(futo@core-sdi.com)
1062          */
1063         if (!receive_context.plaintext) {
1064                 switch (detect_attack(buffer_ptr(&input), padded_len)) {
1065                 case DEATTACK_DETECTED:
1066                         packet_disconnect("crc32 compensation attack: "
1067                             "network attack detected");
1068                 case DEATTACK_DOS_DETECTED:
1069                         packet_disconnect("deattack denial of "
1070                             "service detected");
1071                 }
1072         }
1073
1074         /* Decrypt data to incoming_packet. */
1075         buffer_clear(&incoming_packet);
1076         cp = buffer_append_space(&incoming_packet, padded_len);
1077         cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1078
1079         buffer_consume(&input, padded_len);
1080
1081 #ifdef PACKET_DEBUG
1082         fprintf(stderr, "read_poll plain: ");
1083         buffer_dump(&incoming_packet);
1084 #endif
1085
1086         /* Compute packet checksum. */
1087         checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1088             buffer_len(&incoming_packet) - 4);
1089
1090         /* Skip padding. */
1091         buffer_consume(&incoming_packet, 8 - len % 8);
1092
1093         /* Test check bytes. */
1094         if (len != buffer_len(&incoming_packet))
1095                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1096                     len, buffer_len(&incoming_packet));
1097
1098         cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1099         stored_checksum = get_u32(cp);
1100         if (checksum != stored_checksum)
1101                 packet_disconnect("Corrupted check bytes on input.");
1102         buffer_consume_end(&incoming_packet, 4);
1103
1104         if (packet_compression) {
1105                 buffer_clear(&compression_buffer);
1106                 buffer_uncompress(&incoming_packet, &compression_buffer);
1107                 buffer_clear(&incoming_packet);
1108                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1109                     buffer_len(&compression_buffer));
1110         }
1111         p_read.packets++;
1112         p_read.bytes += padded_len + 4;
1113         type = buffer_get_char(&incoming_packet);
1114         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1115                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1116         return type;
1117 }
1118
1119 static int
1120 packet_read_poll2(u_int32_t *seqnr_p)
1121 {
1122         static u_int packet_length = 0;
1123         u_int padlen, need;
1124         u_char *macbuf, *cp, type;
1125         u_int maclen, block_size;
1126         Enc *enc   = NULL;
1127         Mac *mac   = NULL;
1128         Comp *comp = NULL;
1129
1130         if (newkeys[MODE_IN] != NULL) {
1131                 enc  = &newkeys[MODE_IN]->enc;
1132                 mac  = &newkeys[MODE_IN]->mac;
1133                 comp = &newkeys[MODE_IN]->comp;
1134         }
1135         maclen = mac && mac->enabled ? mac->mac_len : 0;
1136         block_size = enc ? enc->block_size : 8;
1137
1138         if (packet_length == 0) {
1139                 /*
1140                  * check if input size is less than the cipher block size,
1141                  * decrypt first block and extract length of incoming packet
1142                  */
1143                 if (buffer_len(&input) < block_size)
1144                         return SSH_MSG_NONE;
1145                 buffer_clear(&incoming_packet);
1146                 cp = buffer_append_space(&incoming_packet, block_size);
1147                 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1148                     block_size);
1149                 cp = buffer_ptr(&incoming_packet);
1150                 packet_length = get_u32(cp);
1151                 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1152 #ifdef PACKET_DEBUG
1153                         buffer_dump(&incoming_packet);
1154 #endif
1155                         packet_disconnect("Bad packet length %-10u",
1156                             packet_length);
1157                 }
1158                 DBG(debug("input: packet len %u", packet_length+4));
1159                 buffer_consume(&input, block_size);
1160         }
1161         /* we have a partial packet of block_size bytes */
1162         need = 4 + packet_length - block_size;
1163         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1164             need, maclen));
1165         if (need % block_size != 0) {
1166                 logit("padding error: need %d block %d mod %d",
1167                     need, block_size, need % block_size);
1168                 packet_disconnect("Bad packet length %-10u", packet_length);
1169         }
1170         /*
1171          * check if the entire packet has been received and
1172          * decrypt into incoming_packet
1173          */
1174         if (buffer_len(&input) < need + maclen)
1175                 return SSH_MSG_NONE;
1176 #ifdef PACKET_DEBUG
1177         fprintf(stderr, "read_poll enc/full: ");
1178         buffer_dump(&input);
1179 #endif
1180         cp = buffer_append_space(&incoming_packet, need);
1181         cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1182         buffer_consume(&input, need);
1183         /*
1184          * compute MAC over seqnr and packet,
1185          * increment sequence number for incoming packet
1186          */
1187         if (mac && mac->enabled) {
1188                 macbuf = mac_compute(mac, p_read.seqnr,
1189                     buffer_ptr(&incoming_packet),
1190                     buffer_len(&incoming_packet));
1191                 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1192                         packet_disconnect("Corrupted MAC on input.");
1193                 DBG(debug("MAC #%d ok", p_read.seqnr));
1194                 buffer_consume(&input, mac->mac_len);
1195         }
1196         if (seqnr_p != NULL)
1197                 *seqnr_p = p_read.seqnr;
1198         if (++p_read.seqnr == 0)
1199                 logit("incoming seqnr wraps around");
1200         if (++p_read.packets == 0)
1201                 if (!(datafellows & SSH_BUG_NOREKEY))
1202                         fatal("XXX too many packets with same key");
1203         p_read.blocks += (packet_length + 4) / block_size;
1204         p_read.bytes += packet_length + 4;
1205
1206         /* get padlen */
1207         cp = buffer_ptr(&incoming_packet);
1208         padlen = cp[4];
1209         DBG(debug("input: padlen %d", padlen));
1210         if (padlen < 4)
1211                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1212
1213         /* skip packet size + padlen, discard padding */
1214         buffer_consume(&incoming_packet, 4 + 1);
1215         buffer_consume_end(&incoming_packet, padlen);
1216
1217         DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1218         if (comp && comp->enabled) {
1219                 buffer_clear(&compression_buffer);
1220                 buffer_uncompress(&incoming_packet, &compression_buffer);
1221                 buffer_clear(&incoming_packet);
1222                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1223                     buffer_len(&compression_buffer));
1224                 DBG(debug("input: len after de-compress %d",
1225                     buffer_len(&incoming_packet)));
1226         }
1227         /*
1228          * get packet type, implies consume.
1229          * return length of payload (without type field)
1230          */
1231         type = buffer_get_char(&incoming_packet);
1232         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1233                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1234         if (type == SSH2_MSG_NEWKEYS)
1235                 set_newkeys(MODE_IN);
1236         else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1237                 packet_enable_delayed_compress();
1238 #ifdef PACKET_DEBUG
1239         fprintf(stderr, "read/plain[%d]:\r\n", type);
1240         buffer_dump(&incoming_packet);
1241 #endif
1242         /* reset for next packet */
1243         packet_length = 0;
1244         return type;
1245 }
1246
1247 int
1248 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1249 {
1250         u_int reason, seqnr;
1251         u_char type;
1252         char *msg;
1253
1254         for (;;) {
1255                 if (compat20) {
1256                         type = packet_read_poll2(seqnr_p);
1257                         if (type) {
1258                                 keep_alive_timeouts = 0;
1259                                 DBG(debug("received packet type %d", type));
1260                         }
1261                         switch (type) {
1262                         case SSH2_MSG_IGNORE:
1263                                 debug3("Received SSH2_MSG_IGNORE");
1264                                 break;
1265                         case SSH2_MSG_DEBUG:
1266                                 packet_get_char();
1267                                 msg = packet_get_string(NULL);
1268                                 debug("Remote: %.900s", msg);
1269                                 xfree(msg);
1270                                 msg = packet_get_string(NULL);
1271                                 xfree(msg);
1272                                 break;
1273                         case SSH2_MSG_DISCONNECT:
1274                                 reason = packet_get_int();
1275                                 msg = packet_get_string(NULL);
1276                                 logit("Received disconnect from %s: %u: %.400s",
1277                                     get_remote_ipaddr(), reason, msg);
1278                                 xfree(msg);
1279                                 cleanup_exit(255);
1280                                 break;
1281                         case SSH2_MSG_UNIMPLEMENTED:
1282                                 seqnr = packet_get_int();
1283                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1284                                     seqnr);
1285                                 break;
1286                         default:
1287                                 return type;
1288                         }
1289                 } else {
1290                         type = packet_read_poll1();
1291                         switch (type) {
1292                         case SSH_MSG_IGNORE:
1293                                 break;
1294                         case SSH_MSG_DEBUG:
1295                                 msg = packet_get_string(NULL);
1296                                 debug("Remote: %.900s", msg);
1297                                 xfree(msg);
1298                                 break;
1299                         case SSH_MSG_DISCONNECT:
1300                                 msg = packet_get_string(NULL);
1301                                 logit("Received disconnect from %s: %.400s",
1302                                     get_remote_ipaddr(), msg);
1303                                 cleanup_exit(255);
1304                                 break;
1305                         default:
1306                                 if (type)
1307                                         DBG(debug("received packet type %d", type));
1308                                 return type;
1309                         }
1310                 }
1311         }
1312 }
1313
1314 int
1315 packet_read_poll(void)
1316 {
1317         return packet_read_poll_seqnr(NULL);
1318 }
1319
1320 /*
1321  * Buffers the given amount of input characters.  This is intended to be used
1322  * together with packet_read_poll.
1323  */
1324
1325 void
1326 packet_process_incoming(const char *buf, u_int len)
1327 {
1328         buffer_append(&input, buf, len);
1329 }
1330
1331 /* Returns a character from the packet. */
1332
1333 u_int
1334 packet_get_char(void)
1335 {
1336         char ch;
1337
1338         buffer_get(&incoming_packet, &ch, 1);
1339         return (u_char) ch;
1340 }
1341
1342 /* Returns an integer from the packet data. */
1343
1344 u_int
1345 packet_get_int(void)
1346 {
1347         return buffer_get_int(&incoming_packet);
1348 }
1349
1350 /*
1351  * Returns an arbitrary precision integer from the packet data.  The integer
1352  * must have been initialized before this call.
1353  */
1354
1355 void
1356 packet_get_bignum(BIGNUM * value)
1357 {
1358         buffer_get_bignum(&incoming_packet, value);
1359 }
1360
1361 void
1362 packet_get_bignum2(BIGNUM * value)
1363 {
1364         buffer_get_bignum2(&incoming_packet, value);
1365 }
1366
1367 void *
1368 packet_get_raw(u_int *length_ptr)
1369 {
1370         u_int bytes = buffer_len(&incoming_packet);
1371
1372         if (length_ptr != NULL)
1373                 *length_ptr = bytes;
1374         return buffer_ptr(&incoming_packet);
1375 }
1376
1377 int
1378 packet_remaining(void)
1379 {
1380         return buffer_len(&incoming_packet);
1381 }
1382
1383 /*
1384  * Returns a string from the packet data.  The string is allocated using
1385  * xmalloc; it is the responsibility of the calling program to free it when
1386  * no longer needed.  The length_ptr argument may be NULL, or point to an
1387  * integer into which the length of the string is stored.
1388  */
1389
1390 void *
1391 packet_get_string(u_int *length_ptr)
1392 {
1393         return buffer_get_string(&incoming_packet, length_ptr);
1394 }
1395
1396 void *
1397 packet_get_string_ptr(u_int *length_ptr)
1398 {
1399         return buffer_get_string_ptr(&incoming_packet, length_ptr);
1400 }
1401
1402 /*
1403  * Sends a diagnostic message from the server to the client.  This message
1404  * can be sent at any time (but not while constructing another message). The
1405  * message is printed immediately, but only if the client is being executed
1406  * in verbose mode.  These messages are primarily intended to ease debugging
1407  * authentication problems.   The length of the formatted message must not
1408  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1409  */
1410
1411 void
1412 packet_send_debug(const char *fmt,...)
1413 {
1414         char buf[1024];
1415         va_list args;
1416
1417         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1418                 return;
1419
1420         va_start(args, fmt);
1421         vsnprintf(buf, sizeof(buf), fmt, args);
1422         va_end(args);
1423
1424         if (compat20) {
1425                 packet_start(SSH2_MSG_DEBUG);
1426                 packet_put_char(0);     /* bool: always display */
1427                 packet_put_cstring(buf);
1428                 packet_put_cstring("");
1429         } else {
1430                 packet_start(SSH_MSG_DEBUG);
1431                 packet_put_cstring(buf);
1432         }
1433         packet_send();
1434         packet_write_wait();
1435 }
1436
1437 /*
1438  * Logs the error plus constructs and sends a disconnect packet, closes the
1439  * connection, and exits.  This function never returns. The error message
1440  * should not contain a newline.  The length of the formatted message must
1441  * not exceed 1024 bytes.
1442  */
1443
1444 void
1445 packet_disconnect(const char *fmt,...)
1446 {
1447         char buf[1024];
1448         va_list args;
1449         static int disconnecting = 0;
1450
1451         if (disconnecting)      /* Guard against recursive invocations. */
1452                 fatal("packet_disconnect called recursively.");
1453         disconnecting = 1;
1454
1455         /*
1456          * Format the message.  Note that the caller must make sure the
1457          * message is of limited size.
1458          */
1459         va_start(args, fmt);
1460         vsnprintf(buf, sizeof(buf), fmt, args);
1461         va_end(args);
1462
1463         /* Display the error locally */
1464         logit("Disconnecting: %.100s", buf);
1465
1466         /* Send the disconnect message to the other side, and wait for it to get sent. */
1467         if (compat20) {
1468                 packet_start(SSH2_MSG_DISCONNECT);
1469                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1470                 packet_put_cstring(buf);
1471                 packet_put_cstring("");
1472         } else {
1473                 packet_start(SSH_MSG_DISCONNECT);
1474                 packet_put_cstring(buf);
1475         }
1476         packet_send();
1477         packet_write_wait();
1478
1479         /* Stop listening for connections. */
1480         channel_close_all();
1481
1482         /* Close the connection. */
1483         packet_close();
1484         cleanup_exit(255);
1485 }
1486
1487 /* Checks if there is any buffered output, and tries to write some of the output. */
1488
1489 void
1490 packet_write_poll(void)
1491 {
1492         int len = buffer_len(&output);
1493
1494         if (len > 0) {
1495                 len = write(connection_out, buffer_ptr(&output), len);
1496                 if (len == -1) {
1497                         if (errno == EINTR || errno == EAGAIN ||
1498                             errno == EWOULDBLOCK)
1499                                 return;
1500                         fatal("Write failed: %.100s", strerror(errno));
1501                 }
1502                 if (len == 0)
1503                         fatal("Write connection closed");
1504                 buffer_consume(&output, len);
1505         }
1506 }
1507
1508
1509 /*
1510  * Calls packet_write_poll repeatedly until all pending output data has been
1511  * written.
1512  */
1513
1514 void
1515 packet_write_wait(void)
1516 {
1517         fd_set *setp;
1518         int ret, ms_remain;
1519         struct timeval start, timeout, *timeoutp = NULL;
1520
1521         setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1522             sizeof(fd_mask));
1523         packet_write_poll();
1524         while (packet_have_data_to_write()) {
1525                 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1526                     sizeof(fd_mask));
1527                 FD_SET(connection_out, setp);
1528
1529                 if (packet_timeout_ms > 0) {
1530                         ms_remain = packet_timeout_ms;
1531                         timeoutp = &timeout;
1532                 }
1533                 for (;;) {
1534                         if (packet_timeout_ms != -1) {
1535                                 ms_to_timeval(&timeout, ms_remain);
1536                                 gettimeofday(&start, NULL);
1537                         }
1538                         if ((ret = select(connection_out + 1, NULL, setp,
1539                             NULL, timeoutp)) >= 0)
1540                                 break;
1541                         if (errno != EAGAIN && errno != EINTR &&
1542                             errno != EWOULDBLOCK)
1543                                 break;
1544                         if (packet_timeout_ms == -1)
1545                                 continue;
1546                         ms_subtract_diff(&start, &ms_remain);
1547                         if (ms_remain <= 0) {
1548                                 ret = 0;
1549                                 break;
1550                         }
1551                 }
1552                 if (ret == 0) {
1553                         logit("Connection to %.200s timed out while "
1554                             "waiting to write", get_remote_ipaddr());
1555                         cleanup_exit(255);
1556                 }
1557                 packet_write_poll();
1558         }
1559         xfree(setp);
1560 }
1561
1562 /* Returns true if there is buffered data to write to the connection. */
1563
1564 int
1565 packet_have_data_to_write(void)
1566 {
1567         return buffer_len(&output) != 0;
1568 }
1569
1570 /* Returns true if there is not too much data to write to the connection. */
1571
1572 int
1573 packet_not_very_much_data_to_write(void)
1574 {
1575         if (interactive_mode)
1576                 return buffer_len(&output) < 16384;
1577         else
1578                 return buffer_len(&output) < 128 * 1024;
1579 }
1580
1581
1582 static void
1583 packet_set_tos(int interactive)
1584 {
1585 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1586         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1587
1588         if (!packet_connection_is_on_socket() ||
1589             !packet_connection_is_ipv4())
1590                 return;
1591         if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1592             sizeof(tos)) < 0)
1593                 error("setsockopt IP_TOS %d: %.100s:",
1594                     tos, strerror(errno));
1595 #endif
1596 }
1597
1598 /* Informs that the current session is interactive.  Sets IP flags for that. */
1599
1600 void
1601 packet_set_interactive(int interactive)
1602 {
1603         static int called = 0;
1604
1605         if (called)
1606                 return;
1607         called = 1;
1608
1609         /* Record that we are in interactive mode. */
1610         interactive_mode = interactive;
1611
1612         /* Only set socket options if using a socket.  */
1613         if (!packet_connection_is_on_socket())
1614                 return;
1615         set_nodelay(connection_in);
1616         packet_set_tos(interactive);
1617 }
1618
1619 /* Returns true if the current connection is interactive. */
1620
1621 int
1622 packet_is_interactive(void)
1623 {
1624         return interactive_mode;
1625 }
1626
1627 int
1628 packet_set_maxsize(u_int s)
1629 {
1630         static int called = 0;
1631
1632         if (called) {
1633                 logit("packet_set_maxsize: called twice: old %d new %d",
1634                     max_packet_size, s);
1635                 return -1;
1636         }
1637         if (s < 4 * 1024 || s > 1024 * 1024) {
1638                 logit("packet_set_maxsize: bad size %d", s);
1639                 return -1;
1640         }
1641         called = 1;
1642         debug("packet_set_maxsize: setting to %d", s);
1643         max_packet_size = s;
1644         return s;
1645 }
1646
1647 /* roundup current message to pad bytes */
1648 void
1649 packet_add_padding(u_char pad)
1650 {
1651         extra_pad = pad;
1652 }
1653
1654 /*
1655  * 9.2.  Ignored Data Message
1656  *
1657  *   byte      SSH_MSG_IGNORE
1658  *   string    data
1659  *
1660  * All implementations MUST understand (and ignore) this message at any
1661  * time (after receiving the protocol version). No implementation is
1662  * required to send them. This message can be used as an additional
1663  * protection measure against advanced traffic analysis techniques.
1664  */
1665 void
1666 packet_send_ignore(int nbytes)
1667 {
1668         u_int32_t rnd = 0;
1669         int i;
1670
1671         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1672         packet_put_int(nbytes);
1673         for (i = 0; i < nbytes; i++) {
1674                 if (i % 4 == 0)
1675                         rnd = arc4random();
1676                 packet_put_char((u_char)rnd & 0xff);
1677                 rnd >>= 8;
1678         }
1679 }
1680
1681 #define MAX_PACKETS     (1U<<31)
1682 int
1683 packet_need_rekeying(void)
1684 {
1685         if (datafellows & SSH_BUG_NOREKEY)
1686                 return 0;
1687         return
1688             (p_send.packets > MAX_PACKETS) ||
1689             (p_read.packets > MAX_PACKETS) ||
1690             (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1691             (max_blocks_in  && (p_read.blocks > max_blocks_in));
1692 }
1693
1694 void
1695 packet_set_rekey_limit(u_int32_t bytes)
1696 {
1697         rekey_limit = bytes;
1698 }
1699
1700 void
1701 packet_set_server(void)
1702 {
1703         server_side = 1;
1704 }
1705
1706 void
1707 packet_set_authenticated(void)
1708 {
1709         after_authentication = 1;
1710 }