openssh/packet.c

   1 /* $OpenBSD: packet.c,v 1.157 2008/07/10 18:08:11 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 int
 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         return(packet_length);
 856 }
 857
 858 static int
 859 packet_send2(void)
 860 {
 861         static int packet_length = 0;
 862         static int rekeying = 0;
 863         struct packet *p;
 864         u_char type, *cp;
 865
 866         cp = buffer_ptr(&outgoing_packet);
 867         type = cp[5];
 868
 869         /* during rekeying we can only send key exchange messages */
 870         if (rekeying) {
 871                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 872                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 873                         debug("enqueue packet: %u", type);
 874                         p = xmalloc(sizeof(*p));
 875                         p->type = type;
 876                         memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
 877                         buffer_init(&outgoing_packet);
 878                         TAILQ_INSERT_TAIL(&outgoing, p, next);
 879                         return(sizeof(Buffer));
 880                 }
 881         }
 882
 883         /* rekeying starts with sending KEXINIT */
 884         if (type == SSH2_MSG_KEXINIT)
 885                 rekeying = 1;
 886
 887         packet_length = packet_send2_wrapped();
 888
 889         /* after a NEWKEYS message we can send the complete queue */
 890         if (type == SSH2_MSG_NEWKEYS) {
 891                 rekeying = 0;
 892                 while ((p = TAILQ_FIRST(&outgoing))) {
 893                         type = p->type;
 894                         debug("dequeue packet: %u", type);
 895                         buffer_free(&outgoing_packet);
 896                         memcpy(&outgoing_packet, &p->payload,
 897                             sizeof(Buffer));
 898                         TAILQ_REMOVE(&outgoing, p, next);
 899                         xfree(p);
 900                         packet_length += packet_send2_wrapped();
 901                 }
 902         }
 903         return(packet_length);
 904 }
 905
 906 int
 907 packet_send(void)
 908 {
 909   int packet_len = 0;
 910         if (compat20)
 911                 packet_len = packet_send2();
 912         else
 913                 packet_send1();
 914         DBG(debug("packet_send done"));
 915         return(packet_len);
 916 }
 917
 918 /*
 919  * Waits until a packet has been received, and returns its type.  Note that
 920  * no other data is processed until this returns, so this function should not
 921  * be used during the interactive session.
 922  */
 923
 924 int
 925 packet_read_seqnr(u_int32_t *seqnr_p)
 926 {
 927         int type, len, ret, ms_remain;
 928         fd_set *setp;
 929         char buf[8192];
 930         struct timeval timeout, start, *timeoutp = NULL;
 931
 932         DBG(debug("packet_read()"));
 933
 934         setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
 935             sizeof(fd_mask));
 936
 937         /* Since we are blocking, ensure that all written packets have been sent. */
 938         packet_write_wait();
 939
 940         /* Stay in the loop until we have received a complete packet. */
 941         for (;;) {
 942                 /* Try to read a packet from the buffer. */
 943                 type = packet_read_poll_seqnr(seqnr_p);
 944                 if (!compat20 && (
 945                     type == SSH_SMSG_SUCCESS
 946                     || type == SSH_SMSG_FAILURE
 947                     || type == SSH_CMSG_EOF
 948                     || type == SSH_CMSG_EXIT_CONFIRMATION))
 949                         packet_check_eom();
 950                 /* If we got a packet, return it. */
 951                 if (type != SSH_MSG_NONE) {
 952                         xfree(setp);
 953                         return type;
 954                 }
 955                 /*
 956                  * Otherwise, wait for some data to arrive, add it to the
 957                  * buffer, and try again.
 958                  */
 959                 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
 960                     sizeof(fd_mask));
 961                 FD_SET(connection_in, setp);
 962
 963                 if (packet_timeout_ms > 0) {
 964                         ms_remain = packet_timeout_ms;
 965                         timeoutp = &timeout;
 966                 }
 967                 /* Wait for some data to arrive. */
 968                 for (;;) {
 969                         if (packet_timeout_ms != -1) {
 970                                 ms_to_timeval(&timeout, ms_remain);
 971                                 gettimeofday(&start, NULL);
 972                         }
 973                         if ((ret = select(connection_in + 1, setp, NULL,
 974                             NULL, timeoutp)) >= 0)
 975                                 break;
 976                         if (errno != EAGAIN && errno != EINTR &&
 977                             errno != EWOULDBLOCK)
 978                                 break;
 979                         if (packet_timeout_ms == -1)
 980                                 continue;
 981                         ms_subtract_diff(&start, &ms_remain);
 982                         if (ms_remain <= 0) {
 983                                 ret = 0;
 984                                 break;
 985                         }
 986                 }
 987                 if (ret == 0) {
 988                         logit("Connection to %.200s timed out while "
 989                             "waiting to read", get_remote_ipaddr());
 990                         cleanup_exit(255);
 991                 }
 992                 /* Read data from the socket. */
 993                 len = read(connection_in, buf, sizeof(buf));
 994                 if (len == 0) {
 995                         logit("Connection closed by %.200s", get_remote_ipaddr());
 996                         cleanup_exit(255);
 997                 }
 998                 if (len < 0)
 999                         fatal("Read from socket failed: %.100s", strerror(errno));
1000                 /* Append it to the buffer. */
1001                 packet_process_incoming(buf, len);
1002         }
1003         /* NOTREACHED */
1004 }
1005
1006 int
1007 packet_read(void)
1008 {
1009         return packet_read_seqnr(NULL);
1010 }
1011
1012 /*
1013  * Waits until a packet has been received, verifies that its type matches
1014  * that given, and gives a fatal error and exits if there is a mismatch.
1015  */
1016
1017 void
1018 packet_read_expect(int expected_type)
1019 {
1020         int type;
1021
1022         type = packet_read();
1023         if (type != expected_type)
1024                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1025                     expected_type, type);
1026 }
1027
1028 /* Checks if a full packet is available in the data received so far via
1029  * packet_process_incoming.  If so, reads the packet; otherwise returns
1030  * SSH_MSG_NONE.  This does not wait for data from the connection.
1031  *
1032  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1033  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1034  * to higher levels.
1035  */
1036
1037 static int
1038 packet_read_poll1(void)
1039 {
1040         u_int len, padded_len;
1041         u_char *cp, type;
1042         u_int checksum, stored_checksum;
1043
1044         /* Check if input size is less than minimum packet size. */
1045         if (buffer_len(&input) < 4 + 8)
1046                 return SSH_MSG_NONE;
1047         /* Get length of incoming packet. */
1048         cp = buffer_ptr(&input);
1049         len = get_u32(cp);
1050         if (len < 1 + 2 + 2 || len > 256 * 1024)
1051                 packet_disconnect("Bad packet length %u.", len);
1052         padded_len = (len + 8) & ~7;
1053
1054         /* Check if the packet has been entirely received. */
1055         if (buffer_len(&input) < 4 + padded_len)
1056                 return SSH_MSG_NONE;
1057
1058         /* The entire packet is in buffer. */
1059
1060         /* Consume packet length. */
1061         buffer_consume(&input, 4);
1062
1063         /*
1064          * Cryptographic attack detector for ssh
1065          * (C)1998 CORE-SDI, Buenos Aires Argentina
1066          * Ariel Futoransky(futo@core-sdi.com)
1067          */
1068         if (!receive_context.plaintext) {
1069                 switch (detect_attack(buffer_ptr(&input), padded_len)) {
1070                 case DEATTACK_DETECTED:
1071                         packet_disconnect("crc32 compensation attack: "
1072                             "network attack detected");
1073                 case DEATTACK_DOS_DETECTED:
1074                         packet_disconnect("deattack denial of "
1075                             "service detected");
1076                 }
1077         }
1078
1079         /* Decrypt data to incoming_packet. */
1080         buffer_clear(&incoming_packet);
1081         cp = buffer_append_space(&incoming_packet, padded_len);
1082         cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1083
1084         buffer_consume(&input, padded_len);
1085
1086 #ifdef PACKET_DEBUG
1087         fprintf(stderr, "read_poll plain: ");
1088         buffer_dump(&incoming_packet);
1089 #endif
1090
1091         /* Compute packet checksum. */
1092         checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1093             buffer_len(&incoming_packet) - 4);
1094
1095         /* Skip padding. */
1096         buffer_consume(&incoming_packet, 8 - len % 8);
1097
1098         /* Test check bytes. */
1099         if (len != buffer_len(&incoming_packet))
1100                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1101                     len, buffer_len(&incoming_packet));
1102
1103         cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1104         stored_checksum = get_u32(cp);
1105         if (checksum != stored_checksum)
1106                 packet_disconnect("Corrupted check bytes on input.");
1107         buffer_consume_end(&incoming_packet, 4);
1108
1109         if (packet_compression) {
1110                 buffer_clear(&compression_buffer);
1111                 buffer_uncompress(&incoming_packet, &compression_buffer);
1112                 buffer_clear(&incoming_packet);
1113                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1114                     buffer_len(&compression_buffer));
1115         }
1116         p_read.packets++;
1117         p_read.bytes += padded_len + 4;
1118         type = buffer_get_char(&incoming_packet);
1119         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1120                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1121         return type;
1122 }
1123
1124 static int
1125 packet_read_poll2(u_int32_t *seqnr_p)
1126 {
1127         static u_int packet_length = 0;
1128         u_int padlen, need;
1129         u_char *macbuf, *cp, type;
1130         u_int maclen, block_size;
1131         Enc *enc   = NULL;
1132         Mac *mac   = NULL;
1133         Comp *comp = NULL;
1134
1135         if (newkeys[MODE_IN] != NULL) {
1136                 enc  = &newkeys[MODE_IN]->enc;
1137                 mac  = &newkeys[MODE_IN]->mac;
1138                 comp = &newkeys[MODE_IN]->comp;
1139         }
1140         maclen = mac && mac->enabled ? mac->mac_len : 0;
1141         block_size = enc ? enc->block_size : 8;
1142
1143         if (packet_length == 0) {
1144                 /*
1145                  * check if input size is less than the cipher block size,
1146                  * decrypt first block and extract length of incoming packet
1147                  */
1148                 if (buffer_len(&input) < block_size)
1149                         return SSH_MSG_NONE;
1150                 buffer_clear(&incoming_packet);
1151                 cp = buffer_append_space(&incoming_packet, block_size);
1152                 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1153                     block_size);
1154                 cp = buffer_ptr(&incoming_packet);
1155                 packet_length = get_u32(cp);
1156                 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1157 #ifdef PACKET_DEBUG
1158                         buffer_dump(&incoming_packet);
1159 #endif
1160                         packet_disconnect("Bad packet length %u.", packet_length);
1161                 }
1162                 DBG(debug("input: packet len %u", packet_length+4));
1163                 buffer_consume(&input, block_size);
1164         }
1165         /* we have a partial packet of block_size bytes */
1166         need = 4 + packet_length - block_size;
1167         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1168             need, maclen));
1169         if (need % block_size != 0)
1170                 fatal("padding error: need %d block %d mod %d",
1171                     need, block_size, need % block_size);
1172         /*
1173          * check if the entire packet has been received and
1174          * decrypt into incoming_packet
1175          */
1176         if (buffer_len(&input) < need + maclen)
1177                 return SSH_MSG_NONE;
1178 #ifdef PACKET_DEBUG
1179         fprintf(stderr, "read_poll enc/full: ");
1180         buffer_dump(&input);
1181 #endif
1182         cp = buffer_append_space(&incoming_packet, need);
1183         cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1184         buffer_consume(&input, need);
1185         /*
1186          * compute MAC over seqnr and packet,
1187          * increment sequence number for incoming packet
1188          */
1189         if (mac && mac->enabled) {
1190                 macbuf = mac_compute(mac, p_read.seqnr,
1191                     buffer_ptr(&incoming_packet),
1192                     buffer_len(&incoming_packet));
1193                 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1194                         packet_disconnect("Corrupted MAC on input.");
1195                 DBG(debug("MAC #%d ok", p_read.seqnr));
1196                 buffer_consume(&input, mac->mac_len);
1197         }
1198         if (seqnr_p != NULL)
1199                 *seqnr_p = p_read.seqnr;
1200         if (++p_read.seqnr == 0)
1201                 logit("incoming seqnr wraps around");
1202         if (++p_read.packets == 0)
1203                 if (!(datafellows & SSH_BUG_NOREKEY))
1204                         fatal("XXX too many packets with same key");
1205         p_read.blocks += (packet_length + 4) / block_size;
1206         p_read.bytes += packet_length + 4;
1207
1208         /* get padlen */
1209         cp = buffer_ptr(&incoming_packet);
1210         padlen = cp[4];
1211         DBG(debug("input: padlen %d", padlen));
1212         if (padlen < 4)
1213                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1214
1215         /* skip packet size + padlen, discard padding */
1216         buffer_consume(&incoming_packet, 4 + 1);
1217         buffer_consume_end(&incoming_packet, padlen);
1218
1219         DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1220         if (comp && comp->enabled) {
1221                 buffer_clear(&compression_buffer);
1222                 buffer_uncompress(&incoming_packet, &compression_buffer);
1223                 buffer_clear(&incoming_packet);
1224                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1225                     buffer_len(&compression_buffer));
1226                 DBG(debug("input: len after de-compress %d",
1227                     buffer_len(&incoming_packet)));
1228         }
1229         /*
1230          * get packet type, implies consume.
1231          * return length of payload (without type field)
1232          */
1233         type = buffer_get_char(&incoming_packet);
1234         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1235                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1236         if (type == SSH2_MSG_NEWKEYS)
1237                 set_newkeys(MODE_IN);
1238         else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1239                 packet_enable_delayed_compress();
1240 #ifdef PACKET_DEBUG
1241         fprintf(stderr, "read/plain[%d]:\r\n", type);
1242         buffer_dump(&incoming_packet);
1243 #endif
1244         /* reset for next packet */
1245         packet_length = 0;
1246         return type;
1247 }
1248
1249 int
1250 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1251 {
1252         u_int reason, seqnr;
1253         u_char type;
1254         char *msg;
1255
1256         for (;;) {
1257                 if (compat20) {
1258                         type = packet_read_poll2(seqnr_p);
1259                         if (type) {
1260                                 keep_alive_timeouts = 0;
1261                                 DBG(debug("received packet type %d", type));
1262                         }
1263                         switch (type) {
1264                         case SSH2_MSG_IGNORE:
1265                                 debug3("Received SSH2_MSG_IGNORE");
1266                                 break;
1267                         case SSH2_MSG_DEBUG:
1268                                 packet_get_char();
1269                                 msg = packet_get_string(NULL);
1270                                 debug("Remote: %.900s", msg);
1271                                 xfree(msg);
1272                                 msg = packet_get_string(NULL);
1273                                 xfree(msg);
1274                                 break;
1275                         case SSH2_MSG_DISCONNECT:
1276                                 reason = packet_get_int();
1277                                 msg = packet_get_string(NULL);
1278                                 logit("Received disconnect from %s: %u: %.400s",
1279                                     get_remote_ipaddr(), reason, msg);
1280                                 xfree(msg);
1281                                 cleanup_exit(255);
1282                                 break;
1283                         case SSH2_MSG_UNIMPLEMENTED:
1284                                 seqnr = packet_get_int();
1285                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1286                                     seqnr);
1287                                 break;
1288                         default:
1289                                 return type;
1290                         }
1291                 } else {
1292                         type = packet_read_poll1();
1293                         switch (type) {
1294                         case SSH_MSG_IGNORE:
1295                                 break;
1296                         case SSH_MSG_DEBUG:
1297                                 msg = packet_get_string(NULL);
1298                                 debug("Remote: %.900s", msg);
1299                                 xfree(msg);
1300                                 break;
1301                         case SSH_MSG_DISCONNECT:
1302                                 msg = packet_get_string(NULL);
1303                                 logit("Received disconnect from %s: %.400s",
1304                                     get_remote_ipaddr(), msg);
1305                                 cleanup_exit(255);
1306                                 break;
1307                         default:
1308                                 if (type)
1309                                         DBG(debug("received packet type %d", type));
1310                                 return type;
1311                         }
1312                 }
1313         }
1314 }
1315
1316 int
1317 packet_read_poll(void)
1318 {
1319         return packet_read_poll_seqnr(NULL);
1320 }
1321
1322 /*
1323  * Buffers the given amount of input characters.  This is intended to be used
1324  * together with packet_read_poll.
1325  */
1326
1327 void
1328 packet_process_incoming(const char *buf, u_int len)
1329 {
1330         buffer_append(&input, buf, len);
1331 }
1332
1333 /* Returns a character from the packet. */
1334
1335 u_int
1336 packet_get_char(void)
1337 {
1338         char ch;
1339
1340         buffer_get(&incoming_packet, &ch, 1);
1341         return (u_char) ch;
1342 }
1343
1344 /* Returns an integer from the packet data. */
1345
1346 u_int
1347 packet_get_int(void)
1348 {
1349         return buffer_get_int(&incoming_packet);
1350 }
1351
1352 /*
1353  * Returns an arbitrary precision integer from the packet data.  The integer
1354  * must have been initialized before this call.
1355  */
1356
1357 void
1358 packet_get_bignum(BIGNUM * value)
1359 {
1360         buffer_get_bignum(&incoming_packet, value);
1361 }
1362
1363 void
1364 packet_get_bignum2(BIGNUM * value)
1365 {
1366         buffer_get_bignum2(&incoming_packet, value);
1367 }
1368
1369 void *
1370 packet_get_raw(u_int *length_ptr)
1371 {
1372         u_int bytes = buffer_len(&incoming_packet);
1373
1374         if (length_ptr != NULL)
1375                 *length_ptr = bytes;
1376         return buffer_ptr(&incoming_packet);
1377 }
1378
1379 int
1380 packet_remaining(void)
1381 {
1382         return buffer_len(&incoming_packet);
1383 }
1384
1385 /*
1386  * Returns a string from the packet data.  The string is allocated using
1387  * xmalloc; it is the responsibility of the calling program to free it when
1388  * no longer needed.  The length_ptr argument may be NULL, or point to an
1389  * integer into which the length of the string is stored.
1390  */
1391
1392 void *
1393 packet_get_string(u_int *length_ptr)
1394 {
1395         return buffer_get_string(&incoming_packet, length_ptr);
1396 }
1397
1398 void *
1399 packet_get_string_ptr(u_int *length_ptr)
1400 {
1401         return buffer_get_string_ptr(&incoming_packet, length_ptr);
1402 }
1403
1404 /*
1405  * Sends a diagnostic message from the server to the client.  This message
1406  * can be sent at any time (but not while constructing another message). The
1407  * message is printed immediately, but only if the client is being executed
1408  * in verbose mode.  These messages are primarily intended to ease debugging
1409  * authentication problems.   The length of the formatted message must not
1410  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1411  */
1412
1413 void
1414 packet_send_debug(const char *fmt,...)
1415 {
1416         char buf[1024];
1417         va_list args;
1418
1419         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1420                 return;
1421
1422         va_start(args, fmt);
1423         vsnprintf(buf, sizeof(buf), fmt, args);
1424         va_end(args);
1425
1426         if (compat20) {
1427                 packet_start(SSH2_MSG_DEBUG);
1428                 packet_put_char(0);     /* bool: always display */
1429                 packet_put_cstring(buf);
1430                 packet_put_cstring("");
1431         } else {
1432                 packet_start(SSH_MSG_DEBUG);
1433                 packet_put_cstring(buf);
1434         }
1435         packet_send();
1436         packet_write_wait();
1437 }
1438
1439 /*
1440  * Logs the error plus constructs and sends a disconnect packet, closes the
1441  * connection, and exits.  This function never returns. The error message
1442  * should not contain a newline.  The length of the formatted message must
1443  * not exceed 1024 bytes.
1444  */
1445
1446 void
1447 packet_disconnect(const char *fmt,...)
1448 {
1449         char buf[1024];
1450         va_list args;
1451         static int disconnecting = 0;
1452
1453         if (disconnecting)      /* Guard against recursive invocations. */
1454                 fatal("packet_disconnect called recursively.");
1455         disconnecting = 1;
1456
1457         /*
1458          * Format the message.  Note that the caller must make sure the
1459          * message is of limited size.
1460          */
1461         va_start(args, fmt);
1462         vsnprintf(buf, sizeof(buf), fmt, args);
1463         va_end(args);
1464
1465         /* Display the error locally */
1466         logit("Disconnecting: %.100s", buf);
1467
1468         /* Send the disconnect message to the other side, and wait for it to get sent. */
1469         if (compat20) {
1470                 packet_start(SSH2_MSG_DISCONNECT);
1471                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1472                 packet_put_cstring(buf);
1473                 packet_put_cstring("");
1474         } else {
1475                 packet_start(SSH_MSG_DISCONNECT);
1476                 packet_put_cstring(buf);
1477         }
1478         packet_send();
1479         packet_write_wait();
1480
1481         /* Stop listening for connections. */
1482         channel_close_all();
1483
1484         /* Close the connection. */
1485         packet_close();
1486         cleanup_exit(255);
1487 }
1488
1489 /* Checks if there is any buffered output, and tries to write some of the output. */
1490
1491 int
1492 packet_write_poll(void)
1493 {
1494         int len = 0;
1495         len = buffer_len(&output);
1496
1497         if (len > 0) {
1498                 len = write(connection_out, buffer_ptr(&output), len);
1499                 if (len == -1) {
1500                         if (errno == EINTR || errno == EAGAIN ||
1501                             errno == EWOULDBLOCK)
1502                                 return;
1503                         fatal("Write failed: %.100s", strerror(errno));
1504                 }
1505                 if (len == 0)
1506                         fatal("Write connection closed");
1507                 buffer_consume(&output, len);
1508         }
1509         return(len);
1510 }
1511
1512
1513 /*
1514  * Calls packet_write_poll repeatedly until all pending output data has been
1515  * written.
1516  */
1517
1518 int
1519 packet_write_wait(void)
1520 {
1521         fd_set *setp;
1522         u_int bytes_sent = 0;
1523         int ret, ms_remain;
1524         struct timeval start, timeout, *timeoutp = NULL;
1525
1526         setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1527             sizeof(fd_mask));
1528         bytes_sent += packet_write_poll();
1529         while (packet_have_data_to_write()) {
1530                 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1531                     sizeof(fd_mask));
1532                 FD_SET(connection_out, setp);
1533
1534                 if (packet_timeout_ms > 0) {
1535                         ms_remain = packet_timeout_ms;
1536                         timeoutp = &timeout;
1537                 }
1538                 for (;;) {
1539                         if (packet_timeout_ms != -1) {
1540                                 ms_to_timeval(&timeout, ms_remain);
1541                                 gettimeofday(&start, NULL);
1542                         }
1543                         if ((ret = select(connection_out + 1, NULL, setp,
1544                             NULL, timeoutp)) >= 0)
1545                                 break;
1546                         if (errno != EAGAIN && errno != EINTR &&
1547                             errno != EWOULDBLOCK)
1548                                 break;
1549                         if (packet_timeout_ms == -1)
1550                                 continue;
1551                         ms_subtract_diff(&start, &ms_remain);
1552                         if (ms_remain <= 0) {
1553                                 ret = 0;
1554                                 break;
1555                         }
1556                 }
1557                 if (ret == 0) {
1558                         logit("Connection to %.200s timed out while "
1559                             "waiting to write", get_remote_ipaddr());
1560                         cleanup_exit(255);
1561                 }
1562                 bytes_sent += packet_write_poll();
1563         }
1564         xfree(setp);
1565         return (bytes_sent);
1566 }
1567
1568 /* Returns true if there is buffered data to write to the connection. */
1569
1570 int
1571 packet_have_data_to_write(void)
1572 {
1573         return buffer_len(&output) != 0;
1574 }
1575
1576 /* Returns true if there is not too much data to write to the connection. */
1577
1578 int
1579 packet_not_very_much_data_to_write(void)
1580 {
1581         if (interactive_mode)
1582                 return buffer_len(&output) < 16384;
1583         else
1584                 return buffer_len(&output) < 128 * 1024;
1585 }
1586
1587
1588 static void
1589 packet_set_tos(int interactive)
1590 {
1591 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1592         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1593
1594         if (!packet_connection_is_on_socket() ||
1595             !packet_connection_is_ipv4())
1596                 return;
1597         if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1598             sizeof(tos)) < 0)
1599                 error("setsockopt IP_TOS %d: %.100s:",
1600                     tos, strerror(errno));
1601 #endif
1602 }
1603
1604 /* Informs that the current session is interactive.  Sets IP flags for that. */
1605
1606 void
1607 packet_set_interactive(int interactive)
1608 {
1609         static int called = 0;
1610
1611         if (called)
1612                 return;
1613         called = 1;
1614
1615         /* Record that we are in interactive mode. */
1616         interactive_mode = interactive;
1617
1618         /* Only set socket options if using a socket.  */
1619         if (!packet_connection_is_on_socket())
1620                 return;
1621         set_nodelay(connection_in);
1622         packet_set_tos(interactive);
1623 }
1624
1625 /* Returns true if the current connection is interactive. */
1626
1627 int
1628 packet_is_interactive(void)
1629 {
1630         return interactive_mode;
1631 }
1632
1633 int
1634 packet_set_maxsize(u_int s)
1635 {
1636         static int called = 0;
1637
1638         if (called) {
1639                 logit("packet_set_maxsize: called twice: old %d new %d",
1640                     max_packet_size, s);
1641                 return -1;
1642         }
1643         if (s < 4 * 1024 || s > 1024 * 1024) {
1644                 logit("packet_set_maxsize: bad size %d", s);
1645                 return -1;
1646         }
1647         called = 1;
1648         debug("packet_set_maxsize: setting to %d", s);
1649         max_packet_size = s;
1650         return s;
1651 }
1652
1653 /* roundup current message to pad bytes */
1654 void
1655 packet_add_padding(u_char pad)
1656 {
1657         extra_pad = pad;
1658 }
1659
1660 /*
1661  * 9.2.  Ignored Data Message
1662  *
1663  *   byte      SSH_MSG_IGNORE
1664  *   string    data
1665  *
1666  * All implementations MUST understand (and ignore) this message at any
1667  * time (after receiving the protocol version). No implementation is
1668  * required to send them. This message can be used as an additional
1669  * protection measure against advanced traffic analysis techniques.
1670  */
1671 void
1672 packet_send_ignore(int nbytes)
1673 {
1674         u_int32_t rnd = 0;
1675         int i;
1676
1677         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1678         packet_put_int(nbytes);
1679         for (i = 0; i < nbytes; i++) {
1680                 if (i % 4 == 0)
1681                         rnd = arc4random();
1682                 packet_put_char((u_char)rnd & 0xff);
1683                 rnd >>= 8;
1684         }
1685 }
1686
1687 int rekey_requested = 0;
1688 void
1689 packet_request_rekeying(void)
1690 {
1691         rekey_requested = 1;
1692 }
1693
1694 #define MAX_PACKETS     (1U<<31)
1695 int
1696 packet_need_rekeying(void)
1697 {
1698         if (datafellows & SSH_BUG_NOREKEY)
1699                 return 0;
1700         if (rekey_requested == 1)
1701         {
1702                 rekey_requested = 0;
1703                 return 1;
1704         }
1705         return
1706             (p_send.packets > MAX_PACKETS) ||
1707             (p_read.packets > MAX_PACKETS) ||
1708             (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1709             (max_blocks_in  && (p_read.blocks > max_blocks_in));
1710 }
1711
1712 void
1713 packet_set_rekey_limit(u_int32_t bytes)
1714 {
1715         rekey_limit = bytes;
1716 }
1717
1718 void
1719 packet_set_server(void)
1720 {
1721         server_side = 1;
1722 }
1723
1724 void
1725 packet_set_authenticated(void)
1726 {
1727         after_authentication = 1;
1728 }
1729
1730 int
1731 packet_authentication_state(void)
1732 {
1733         return(after_authentication);
1734 }