openssh/packet.c

   1 /* $OpenBSD: packet.c,v 1.151 2008/02/22 20:44:02 dtucker 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 /* Session key information for Encryption and MAC */
 142 Newkeys *newkeys[MODE_MAX];
 143 static struct packet_state {
 144         u_int32_t seqnr;
 145         u_int32_t packets;
 146         u_int64_t blocks;
 147 } p_read, p_send;
 148
 149 static u_int64_t max_blocks_in, max_blocks_out;
 150 static u_int32_t rekey_limit;
 151
 152 /* Session key for protocol v1 */
 153 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 154 static u_int ssh1_keylen;
 155
 156 /* roundup current message to extra_pad bytes */
 157 static u_char extra_pad = 0;
 158
 159 struct packet {
 160         TAILQ_ENTRY(packet) next;
 161         u_char type;
 162         Buffer payload;
 163 };
 164 TAILQ_HEAD(, packet) outgoing;
 165
 166 /*
 167  * Sets the descriptors used for communication.  Disables encryption until
 168  * packet_set_encryption_key is called.
 169  */
 170 void
 171 packet_set_connection(int fd_in, int fd_out)
 172 {
 173         Cipher *none = cipher_by_name("none");
 174
 175         if (none == NULL)
 176                 fatal("packet_set_connection: cannot load cipher 'none'");
 177         connection_in = fd_in;
 178         connection_out = fd_out;
 179         cipher_init(&send_context, none, (const u_char *)"",
 180             0, NULL, 0, CIPHER_ENCRYPT);
 181         cipher_init(&receive_context, none, (const u_char *)"",
 182             0, NULL, 0, CIPHER_DECRYPT);
 183         newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
 184         if (!initialized) {
 185                 initialized = 1;
 186                 buffer_init(&input);
 187                 buffer_init(&output);
 188                 buffer_init(&outgoing_packet);
 189                 buffer_init(&incoming_packet);
 190                 TAILQ_INIT(&outgoing);
 191         }
 192 }
 193
 194 /* Returns 1 if remote host is connected via socket, 0 if not. */
 195
 196 int
 197 packet_connection_is_on_socket(void)
 198 {
 199         struct sockaddr_storage from, to;
 200         socklen_t fromlen, tolen;
 201
 202         /* filedescriptors in and out are the same, so it's a socket */
 203         if (connection_in == connection_out)
 204                 return 1;
 205         fromlen = sizeof(from);
 206         memset(&from, 0, sizeof(from));
 207         if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
 208                 return 0;
 209         tolen = sizeof(to);
 210         memset(&to, 0, sizeof(to));
 211         if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
 212                 return 0;
 213         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 214                 return 0;
 215         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 216                 return 0;
 217         return 1;
 218 }
 219
 220 /*
 221  * Exports an IV from the CipherContext required to export the key
 222  * state back from the unprivileged child to the privileged parent
 223  * process.
 224  */
 225
 226 void
 227 packet_get_keyiv(int mode, u_char *iv, u_int len)
 228 {
 229         CipherContext *cc;
 230
 231         if (mode == MODE_OUT)
 232                 cc = &send_context;
 233         else
 234                 cc = &receive_context;
 235
 236         cipher_get_keyiv(cc, iv, len);
 237 }
 238
 239 int
 240 packet_get_keycontext(int mode, u_char *dat)
 241 {
 242         CipherContext *cc;
 243
 244         if (mode == MODE_OUT)
 245                 cc = &send_context;
 246         else
 247                 cc = &receive_context;
 248
 249         return (cipher_get_keycontext(cc, dat));
 250 }
 251
 252 void
 253 packet_set_keycontext(int mode, u_char *dat)
 254 {
 255         CipherContext *cc;
 256
 257         if (mode == MODE_OUT)
 258                 cc = &send_context;
 259         else
 260                 cc = &receive_context;
 261
 262         cipher_set_keycontext(cc, dat);
 263 }
 264
 265 int
 266 packet_get_keyiv_len(int mode)
 267 {
 268         CipherContext *cc;
 269
 270         if (mode == MODE_OUT)
 271                 cc = &send_context;
 272         else
 273                 cc = &receive_context;
 274
 275         return (cipher_get_keyiv_len(cc));
 276 }
 277
 278 void
 279 packet_set_iv(int mode, u_char *dat)
 280 {
 281         CipherContext *cc;
 282
 283         if (mode == MODE_OUT)
 284                 cc = &send_context;
 285         else
 286                 cc = &receive_context;
 287
 288         cipher_set_keyiv(cc, dat);
 289 }
 290
 291 int
 292 packet_get_ssh1_cipher(void)
 293 {
 294         return (cipher_get_number(receive_context.cipher));
 295 }
 296
 297 void
 298 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets)
 299 {
 300         struct packet_state *state;
 301
 302         state = (mode == MODE_IN) ? &p_read : &p_send;
 303         *seqnr = state->seqnr;
 304         *blocks = state->blocks;
 305         *packets = state->packets;
 306 }
 307
 308 void
 309 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets)
 310 {
 311         struct packet_state *state;
 312
 313         state = (mode == MODE_IN) ? &p_read : &p_send;
 314         state->seqnr = seqnr;
 315         state->blocks = blocks;
 316         state->packets = packets;
 317 }
 318
 319 /* returns 1 if connection is via ipv4 */
 320
 321 int
 322 packet_connection_is_ipv4(void)
 323 {
 324         struct sockaddr_storage to;
 325         socklen_t tolen = sizeof(to);
 326
 327         memset(&to, 0, sizeof(to));
 328         if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
 329                 return 0;
 330         if (to.ss_family == AF_INET)
 331                 return 1;
 332 #ifdef IPV4_IN_IPV6
 333         if (to.ss_family == AF_INET6 &&
 334             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 335                 return 1;
 336 #endif
 337         return 0;
 338 }
 339
 340 /* Sets the connection into non-blocking mode. */
 341
 342 void
 343 packet_set_nonblocking(void)
 344 {
 345         /* Set the socket into non-blocking mode. */
 346         set_nonblock(connection_in);
 347
 348         if (connection_out != connection_in)
 349                 set_nonblock(connection_out);
 350 }
 351
 352 /* Returns the socket used for reading. */
 353
 354 int
 355 packet_get_connection_in(void)
 356 {
 357         return connection_in;
 358 }
 359
 360 /* Returns the descriptor used for writing. */
 361
 362 int
 363 packet_get_connection_out(void)
 364 {
 365         return connection_out;
 366 }
 367
 368 /* Closes the connection and clears and frees internal data structures. */
 369
 370 void
 371 packet_close(void)
 372 {
 373         if (!initialized)
 374                 return;
 375         initialized = 0;
 376         if (connection_in == connection_out) {
 377                 shutdown(connection_out, SHUT_RDWR);
 378                 close(connection_out);
 379         } else {
 380                 close(connection_in);
 381                 close(connection_out);
 382         }
 383         buffer_free(&input);
 384         buffer_free(&output);
 385         buffer_free(&outgoing_packet);
 386         buffer_free(&incoming_packet);
 387         if (compression_buffer_ready) {
 388                 buffer_free(&compression_buffer);
 389                 buffer_compress_uninit();
 390         }
 391         cipher_cleanup(&send_context);
 392         cipher_cleanup(&receive_context);
 393 }
 394
 395 /* Sets remote side protocol flags. */
 396
 397 void
 398 packet_set_protocol_flags(u_int protocol_flags)
 399 {
 400         remote_protocol_flags = protocol_flags;
 401 }
 402
 403 /* Returns the remote protocol flags set earlier by the above function. */
 404
 405 u_int
 406 packet_get_protocol_flags(void)
 407 {
 408         return remote_protocol_flags;
 409 }
 410
 411 /*
 412  * Starts packet compression from the next packet on in both directions.
 413  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 414  */
 415
 416 static void
 417 packet_init_compression(void)
 418 {
 419         if (compression_buffer_ready == 1)
 420                 return;
 421         compression_buffer_ready = 1;
 422         buffer_init(&compression_buffer);
 423 }
 424
 425 void
 426 packet_start_compression(int level)
 427 {
 428         if (packet_compression && !compat20)
 429                 fatal("Compression already enabled.");
 430         packet_compression = 1;
 431         packet_init_compression();
 432         buffer_compress_init_send(level);
 433         buffer_compress_init_recv();
 434 }
 435
 436 /*
 437  * Causes any further packets to be encrypted using the given key.  The same
 438  * key is used for both sending and reception.  However, both directions are
 439  * encrypted independently of each other.
 440  */
 441
 442 void
 443 packet_set_encryption_key(const u_char *key, u_int keylen,
 444     int number)
 445 {
 446         Cipher *cipher = cipher_by_number(number);
 447
 448         if (cipher == NULL)
 449                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 450         if (keylen < 20)
 451                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 452         if (keylen > SSH_SESSION_KEY_LENGTH)
 453                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 454         memcpy(ssh1_key, key, keylen);
 455         ssh1_keylen = keylen;
 456         cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
 457         cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
 458 }
 459
 460 u_int
 461 packet_get_encryption_key(u_char *key)
 462 {
 463         if (key == NULL)
 464                 return (ssh1_keylen);
 465         memcpy(key, ssh1_key, ssh1_keylen);
 466         return (ssh1_keylen);
 467 }
 468
 469 /* Start constructing a packet to send. */
 470 void
 471 packet_start(u_char type)
 472 {
 473         u_char buf[9];
 474         int len;
 475
 476         DBG(debug("packet_start[%d]", type));
 477         len = compat20 ? 6 : 9;
 478         memset(buf, 0, len - 1);
 479         buf[len - 1] = type;
 480         buffer_clear(&outgoing_packet);
 481         buffer_append(&outgoing_packet, buf, len);
 482 }
 483
 484 /* Append payload. */
 485 void
 486 packet_put_char(int value)
 487 {
 488         char ch = value;
 489
 490         buffer_append(&outgoing_packet, &ch, 1);
 491 }
 492
 493 void
 494 packet_put_int(u_int value)
 495 {
 496         buffer_put_int(&outgoing_packet, value);
 497 }
 498
 499 void
 500 packet_put_string(const void *buf, u_int len)
 501 {
 502         buffer_put_string(&outgoing_packet, buf, len);
 503 }
 504
 505 void
 506 packet_put_cstring(const char *str)
 507 {
 508         buffer_put_cstring(&outgoing_packet, str);
 509 }
 510
 511 void
 512 packet_put_raw(const void *buf, u_int len)
 513 {
 514         buffer_append(&outgoing_packet, buf, len);
 515 }
 516
 517 void
 518 packet_put_bignum(BIGNUM * value)
 519 {
 520         buffer_put_bignum(&outgoing_packet, value);
 521 }
 522
 523 void
 524 packet_put_bignum2(BIGNUM * value)
 525 {
 526         buffer_put_bignum2(&outgoing_packet, value);
 527 }
 528
 529 /*
 530  * Finalizes and sends the packet.  If the encryption key has been set,
 531  * encrypts the packet before sending.
 532  */
 533
 534 static void
 535 packet_send1(void)
 536 {
 537         u_char buf[8], *cp;
 538         int i, padding, len;
 539         u_int checksum;
 540         u_int32_t rnd = 0;
 541
 542         /*
 543          * If using packet compression, compress the payload of the outgoing
 544          * packet.
 545          */
 546         if (packet_compression) {
 547                 buffer_clear(&compression_buffer);
 548                 /* Skip padding. */
 549                 buffer_consume(&outgoing_packet, 8);
 550                 /* padding */
 551                 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
 552                 buffer_compress(&outgoing_packet, &compression_buffer);
 553                 buffer_clear(&outgoing_packet);
 554                 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
 555                     buffer_len(&compression_buffer));
 556         }
 557         /* Compute packet length without padding (add checksum, remove padding). */
 558         len = buffer_len(&outgoing_packet) + 4 - 8;
 559
 560         /* Insert padding. Initialized to zero in packet_start1() */
 561         padding = 8 - len % 8;
 562         if (!send_context.plaintext) {
 563                 cp = buffer_ptr(&outgoing_packet);
 564                 for (i = 0; i < padding; i++) {
 565                         if (i % 4 == 0)
 566                                 rnd = arc4random();
 567                         cp[7 - i] = rnd & 0xff;
 568                         rnd >>= 8;
 569                 }
 570         }
 571         buffer_consume(&outgoing_packet, 8 - padding);
 572
 573         /* Add check bytes. */
 574         checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
 575             buffer_len(&outgoing_packet));
 576         put_u32(buf, checksum);
 577         buffer_append(&outgoing_packet, buf, 4);
 578
 579 #ifdef PACKET_DEBUG
 580         fprintf(stderr, "packet_send plain: ");
 581         buffer_dump(&outgoing_packet);
 582 #endif
 583
 584         /* Append to output. */
 585         put_u32(buf, len);
 586         buffer_append(&output, buf, 4);
 587         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
 588         cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
 589             buffer_len(&outgoing_packet));
 590
 591 #ifdef PACKET_DEBUG
 592         fprintf(stderr, "encrypted: ");
 593         buffer_dump(&output);
 594 #endif
 595
 596         buffer_clear(&outgoing_packet);
 597
 598         /*
 599          * Note that the packet is now only buffered in output.  It won't be
 600          * actually sent until packet_write_wait or packet_write_poll is
 601          * called.
 602          */
 603 }
 604
 605 void
 606 set_newkeys(int mode)
 607 {
 608         Enc *enc;
 609         Mac *mac;
 610         Comp *comp;
 611         CipherContext *cc;
 612         u_int64_t *max_blocks;
 613         int crypt_type;
 614
 615         debug2("set_newkeys: mode %d", mode);
 616
 617         if (mode == MODE_OUT) {
 618                 cc = &send_context;
 619                 crypt_type = CIPHER_ENCRYPT;
 620                 p_send.packets = p_send.blocks = 0;
 621                 max_blocks = &max_blocks_out;
 622         } else {
 623                 cc = &receive_context;
 624                 crypt_type = CIPHER_DECRYPT;
 625                 p_read.packets = p_read.blocks = 0;
 626                 max_blocks = &max_blocks_in;
 627         }
 628         if (newkeys[mode] != NULL) {
 629                 debug("set_newkeys: rekeying");
 630                 cipher_cleanup(cc);
 631                 enc  = &newkeys[mode]->enc;
 632                 mac  = &newkeys[mode]->mac;
 633                 comp = &newkeys[mode]->comp;
 634                 mac_clear(mac);
 635                 xfree(enc->name);
 636                 xfree(enc->iv);
 637                 xfree(enc->key);
 638                 xfree(mac->name);
 639                 xfree(mac->key);
 640                 xfree(comp->name);
 641                 xfree(newkeys[mode]);
 642         }
 643         newkeys[mode] = kex_get_newkeys(mode);
 644         if (newkeys[mode] == NULL)
 645                 fatal("newkeys: no keys for mode %d", mode);
 646         enc  = &newkeys[mode]->enc;
 647         mac  = &newkeys[mode]->mac;
 648         comp = &newkeys[mode]->comp;
 649         if (mac_init(mac) == 0)
 650                 mac->enabled = 1;
 651         DBG(debug("cipher_init_context: %d", mode));
 652         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 653             enc->iv, enc->block_size, crypt_type);
 654         /* Deleting the keys does not gain extra security */
 655         /* memset(enc->iv,  0, enc->block_size);
 656            memset(enc->key, 0, enc->key_len);
 657            memset(mac->key, 0, mac->key_len); */
 658         if ((comp->type == COMP_ZLIB ||
 659             (comp->type == COMP_DELAYED && after_authentication)) &&
 660             comp->enabled == 0) {
 661                 packet_init_compression();
 662                 if (mode == MODE_OUT)
 663                         buffer_compress_init_send(6);
 664                 else
 665                         buffer_compress_init_recv();
 666                 comp->enabled = 1;
 667         }
 668         /*
 669          * The 2^(blocksize*2) limit is too expensive for 3DES,
 670          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 671          */
 672         if (enc->block_size >= 16)
 673                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 674         else
 675                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 676         if (rekey_limit)
 677                 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
 678 }
 679
 680 /*
 681  * Delayed compression for SSH2 is enabled after authentication:
 682  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 683  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 684  */
 685 static void
 686 packet_enable_delayed_compress(void)
 687 {
 688         Comp *comp = NULL;
 689         int mode;
 690
 691         /*
 692          * Remember that we are past the authentication step, so rekeying
 693          * with COMP_DELAYED will turn on compression immediately.
 694          */
 695         after_authentication = 1;
 696         for (mode = 0; mode < MODE_MAX; mode++) {
 697                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 698                 if (newkeys[mode] == NULL)
 699                         continue;
 700                 comp = &newkeys[mode]->comp;
 701                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 702                         packet_init_compression();
 703                         if (mode == MODE_OUT)
 704                                 buffer_compress_init_send(6);
 705                         else
 706                                 buffer_compress_init_recv();
 707                         comp->enabled = 1;
 708                 }
 709         }
 710 }
 711
 712 /*
 713  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 714  */
 715 static int
 716 packet_send2_wrapped(void)
 717 {
 718         u_char type, *cp, *macbuf = NULL;
 719         u_char padlen, pad;
 720         u_int packet_length = 0;
 721         u_int i, len;
 722         u_int32_t rnd = 0;
 723         Enc *enc   = NULL;
 724         Mac *mac   = NULL;
 725         Comp *comp = NULL;
 726         int block_size;
 727
 728         if (newkeys[MODE_OUT] != NULL) {
 729                 enc  = &newkeys[MODE_OUT]->enc;
 730                 mac  = &newkeys[MODE_OUT]->mac;
 731                 comp = &newkeys[MODE_OUT]->comp;
 732         }
 733         block_size = enc ? enc->block_size : 8;
 734
 735         cp = buffer_ptr(&outgoing_packet);
 736         type = cp[5];
 737
 738 #ifdef PACKET_DEBUG
 739         fprintf(stderr, "plain:     ");
 740         buffer_dump(&outgoing_packet);
 741 #endif
 742
 743         if (comp && comp->enabled) {
 744                 len = buffer_len(&outgoing_packet);
 745                 /* skip header, compress only payload */
 746                 buffer_consume(&outgoing_packet, 5);
 747                 buffer_clear(&compression_buffer);
 748                 buffer_compress(&outgoing_packet, &compression_buffer);
 749                 buffer_clear(&outgoing_packet);
 750                 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
 751                 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
 752                     buffer_len(&compression_buffer));
 753                 DBG(debug("compression: raw %d compressed %d", len,
 754                     buffer_len(&outgoing_packet)));
 755         }
 756
 757         /* sizeof (packet_len + pad_len + payload) */
 758         len = buffer_len(&outgoing_packet);
 759
 760         /*
 761          * calc size of padding, alloc space, get random data,
 762          * minimum padding is 4 bytes
 763          */
 764         padlen = block_size - (len % block_size);
 765         if (padlen < 4)
 766                 padlen += block_size;
 767         if (extra_pad) {
 768                 /* will wrap if extra_pad+padlen > 255 */
 769                 extra_pad  = roundup(extra_pad, block_size);
 770                 pad = extra_pad - ((len + padlen) % extra_pad);
 771                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 772                     pad, len, padlen, extra_pad);
 773                 padlen += pad;
 774                 extra_pad = 0;
 775         }
 776         cp = buffer_append_space(&outgoing_packet, padlen);
 777         if (enc && !send_context.plaintext) {
 778                 /* random padding */
 779                 for (i = 0; i < padlen; i++) {
 780                         if (i % 4 == 0)
 781                                 rnd = arc4random();
 782                         cp[i] = rnd & 0xff;
 783                         rnd >>= 8;
 784                 }
 785         } else {
 786                 /* clear padding */
 787                 memset(cp, 0, padlen);
 788         }
 789         /* packet_length includes payload, padding and padding length field */
 790         packet_length = buffer_len(&outgoing_packet) - 4;
 791         cp = buffer_ptr(&outgoing_packet);
 792         put_u32(cp, packet_length);
 793         cp[4] = padlen;
 794         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 795
 796         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 797         if (mac && mac->enabled) {
 798                 macbuf = mac_compute(mac, p_send.seqnr,
 799                     buffer_ptr(&outgoing_packet),
 800                     buffer_len(&outgoing_packet));
 801                 DBG(debug("done calc MAC out #%d", p_send.seqnr));
 802         }
 803         /* encrypt packet and append to output buffer. */
 804         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
 805         cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
 806             buffer_len(&outgoing_packet));
 807         /* append unencrypted MAC */
 808         if (mac && mac->enabled)
 809                 buffer_append(&output, macbuf, mac->mac_len);
 810 #ifdef PACKET_DEBUG
 811         fprintf(stderr, "encrypted: ");
 812         buffer_dump(&output);
 813 #endif
 814         /* increment sequence number for outgoing packets */
 815         if (++p_send.seqnr == 0)
 816                 logit("outgoing seqnr wraps around");
 817         if (++p_send.packets == 0)
 818                 if (!(datafellows & SSH_BUG_NOREKEY))
 819                         fatal("XXX too many packets with same key");
 820         p_send.blocks += (packet_length + 4) / block_size;
 821         buffer_clear(&outgoing_packet);
 822
 823         if (type == SSH2_MSG_NEWKEYS)
 824                 set_newkeys(MODE_OUT);
 825         else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
 826                 packet_enable_delayed_compress();
 827         return(packet_length);
 828 }
 829
 830 static int
 831 packet_send2(void)
 832 {
 833         static int packet_length = 0;
 834         static int rekeying = 0;
 835         struct packet *p;
 836         u_char type, *cp;
 837
 838         cp = buffer_ptr(&outgoing_packet);
 839         type = cp[5];
 840
 841         /* during rekeying we can only send key exchange messages */
 842         if (rekeying) {
 843                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 844                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 845                         debug("enqueue packet: %u", type);
 846                         p = xmalloc(sizeof(*p));
 847                         p->type = type;
 848                         memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
 849                         buffer_init(&outgoing_packet);
 850                         TAILQ_INSERT_TAIL(&outgoing, p, next);
 851                         return(sizeof(Buffer));
 852                 }
 853         }
 854
 855         /* rekeying starts with sending KEXINIT */
 856         if (type == SSH2_MSG_KEXINIT)
 857                 rekeying = 1;
 858
 859         packet_length = packet_send2_wrapped();
 860
 861         /* after a NEWKEYS message we can send the complete queue */
 862         if (type == SSH2_MSG_NEWKEYS) {
 863                 rekeying = 0;
 864                 while ((p = TAILQ_FIRST(&outgoing))) {
 865                         type = p->type;
 866                         debug("dequeue packet: %u", type);
 867                         buffer_free(&outgoing_packet);
 868                         memcpy(&outgoing_packet, &p->payload,
 869                             sizeof(Buffer));
 870                         TAILQ_REMOVE(&outgoing, p, next);
 871                         xfree(p);
 872                         packet_length += packet_send2_wrapped();
 873                 }
 874         }
 875         return(packet_length);
 876 }
 877
 878 int
 879 packet_send(void)
 880 {
 881   int packet_len = 0;
 882         if (compat20)
 883                 packet_len = packet_send2();
 884         else
 885                 packet_send1();
 886         DBG(debug("packet_send done"));
 887         return(packet_len);
 888 }
 889
 890 /*
 891  * Waits until a packet has been received, and returns its type.  Note that
 892  * no other data is processed until this returns, so this function should not
 893  * be used during the interactive session.
 894  */
 895
 896 int
 897 packet_read_seqnr(u_int32_t *seqnr_p)
 898 {
 899         int type, len;
 900         fd_set *setp;
 901         char buf[8192];
 902         DBG(debug("packet_read()"));
 903
 904         setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
 905             sizeof(fd_mask));
 906
 907         /* Since we are blocking, ensure that all written packets have been sent. */
 908         packet_write_wait();
 909
 910         /* Stay in the loop until we have received a complete packet. */
 911         for (;;) {
 912                 /* Try to read a packet from the buffer. */
 913                 type = packet_read_poll_seqnr(seqnr_p);
 914                 if (!compat20 && (
 915                     type == SSH_SMSG_SUCCESS
 916                     || type == SSH_SMSG_FAILURE
 917                     || type == SSH_CMSG_EOF
 918                     || type == SSH_CMSG_EXIT_CONFIRMATION))
 919                         packet_check_eom();
 920                 /* If we got a packet, return it. */
 921                 if (type != SSH_MSG_NONE) {
 922                         xfree(setp);
 923                         return type;
 924                 }
 925                 /*
 926                  * Otherwise, wait for some data to arrive, add it to the
 927                  * buffer, and try again.
 928                  */
 929                 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
 930                     sizeof(fd_mask));
 931                 FD_SET(connection_in, setp);
 932
 933                 /* Wait for some data to arrive. */
 934                 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
 935                     (errno == EAGAIN || errno == EINTR))
 936                         ;
 937
 938                 /* Read data from the socket. */
 939                 len = read(connection_in, buf, sizeof(buf));
 940                 if (len == 0) {
 941                         logit("Connection closed by %.200s", get_remote_ipaddr());
 942                         cleanup_exit(255);
 943                 }
 944                 if (len < 0)
 945                         fatal("Read from socket failed: %.100s", strerror(errno));
 946                 /* Append it to the buffer. */
 947                 packet_process_incoming(buf, len);
 948         }
 949         /* NOTREACHED */
 950 }
 951
 952 int
 953 packet_read(void)
 954 {
 955         return packet_read_seqnr(NULL);
 956 }
 957
 958 /*
 959  * Waits until a packet has been received, verifies that its type matches
 960  * that given, and gives a fatal error and exits if there is a mismatch.
 961  */
 962
 963 void
 964 packet_read_expect(int expected_type)
 965 {
 966         int type;
 967
 968         type = packet_read();
 969         if (type != expected_type)
 970                 packet_disconnect("Protocol error: expected packet type %d, got %d",
 971                     expected_type, type);
 972 }
 973
 974 /* Checks if a full packet is available in the data received so far via
 975  * packet_process_incoming.  If so, reads the packet; otherwise returns
 976  * SSH_MSG_NONE.  This does not wait for data from the connection.
 977  *
 978  * SSH_MSG_DISCONNECT is handled specially here.  Also,
 979  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
 980  * to higher levels.
 981  */
 982
 983 static int
 984 packet_read_poll1(void)
 985 {
 986         u_int len, padded_len;
 987         u_char *cp, type;
 988         u_int checksum, stored_checksum;
 989
 990         /* Check if input size is less than minimum packet size. */
 991         if (buffer_len(&input) < 4 + 8)
 992                 return SSH_MSG_NONE;
 993         /* Get length of incoming packet. */
 994         cp = buffer_ptr(&input);
 995         len = get_u32(cp);
 996         if (len < 1 + 2 + 2 || len > 256 * 1024)
 997                 packet_disconnect("Bad packet length %u.", len);
 998         padded_len = (len + 8) & ~7;
 999
1000         /* Check if the packet has been entirely received. */
1001         if (buffer_len(&input) < 4 + padded_len)
1002                 return SSH_MSG_NONE;
1003
1004         /* The entire packet is in buffer. */
1005
1006         /* Consume packet length. */
1007         buffer_consume(&input, 4);
1008
1009         /*
1010          * Cryptographic attack detector for ssh
1011          * (C)1998 CORE-SDI, Buenos Aires Argentina
1012          * Ariel Futoransky(futo@core-sdi.com)
1013          */
1014         if (!receive_context.plaintext) {
1015                 switch (detect_attack(buffer_ptr(&input), padded_len)) {
1016                 case DEATTACK_DETECTED:
1017                         packet_disconnect("crc32 compensation attack: "
1018                             "network attack detected");
1019                 case DEATTACK_DOS_DETECTED:
1020                         packet_disconnect("deattack denial of "
1021                             "service detected");
1022                 }
1023         }
1024
1025         /* Decrypt data to incoming_packet. */
1026         buffer_clear(&incoming_packet);
1027         cp = buffer_append_space(&incoming_packet, padded_len);
1028         cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1029
1030         buffer_consume(&input, padded_len);
1031
1032 #ifdef PACKET_DEBUG
1033         fprintf(stderr, "read_poll plain: ");
1034         buffer_dump(&incoming_packet);
1035 #endif
1036
1037         /* Compute packet checksum. */
1038         checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1039             buffer_len(&incoming_packet) - 4);
1040
1041         /* Skip padding. */
1042         buffer_consume(&incoming_packet, 8 - len % 8);
1043
1044         /* Test check bytes. */
1045         if (len != buffer_len(&incoming_packet))
1046                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1047                     len, buffer_len(&incoming_packet));
1048
1049         cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1050         stored_checksum = get_u32(cp);
1051         if (checksum != stored_checksum)
1052                 packet_disconnect("Corrupted check bytes on input.");
1053         buffer_consume_end(&incoming_packet, 4);
1054
1055         if (packet_compression) {
1056                 buffer_clear(&compression_buffer);
1057                 buffer_uncompress(&incoming_packet, &compression_buffer);
1058                 buffer_clear(&incoming_packet);
1059                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1060                     buffer_len(&compression_buffer));
1061         }
1062         type = buffer_get_char(&incoming_packet);
1063         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1064                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1065         return type;
1066 }
1067
1068 static int
1069 packet_read_poll2(u_int32_t *seqnr_p)
1070 {
1071         static u_int packet_length = 0;
1072         u_int padlen, need;
1073         u_char *macbuf, *cp, type;
1074         u_int maclen, block_size;
1075         Enc *enc   = NULL;
1076         Mac *mac   = NULL;
1077         Comp *comp = NULL;
1078
1079         if (newkeys[MODE_IN] != NULL) {
1080                 enc  = &newkeys[MODE_IN]->enc;
1081                 mac  = &newkeys[MODE_IN]->mac;
1082                 comp = &newkeys[MODE_IN]->comp;
1083         }
1084         maclen = mac && mac->enabled ? mac->mac_len : 0;
1085         block_size = enc ? enc->block_size : 8;
1086
1087         if (packet_length == 0) {
1088                 /*
1089                  * check if input size is less than the cipher block size,
1090                  * decrypt first block and extract length of incoming packet
1091                  */
1092                 if (buffer_len(&input) < block_size)
1093                         return SSH_MSG_NONE;
1094                 buffer_clear(&incoming_packet);
1095                 cp = buffer_append_space(&incoming_packet, block_size);
1096                 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1097                     block_size);
1098                 cp = buffer_ptr(&incoming_packet);
1099                 packet_length = get_u32(cp);
1100                 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1101 #ifdef PACKET_DEBUG
1102                         buffer_dump(&incoming_packet);
1103 #endif
1104                         packet_disconnect("Bad packet length %u.", packet_length);
1105                 }
1106                 DBG(debug("input: packet len %u", packet_length+4));
1107                 buffer_consume(&input, block_size);
1108         }
1109         /* we have a partial packet of block_size bytes */
1110         need = 4 + packet_length - block_size;
1111         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1112             need, maclen));
1113         if (need % block_size != 0)
1114                 fatal("padding error: need %d block %d mod %d",
1115                     need, block_size, need % block_size);
1116         /*
1117          * check if the entire packet has been received and
1118          * decrypt into incoming_packet
1119          */
1120         if (buffer_len(&input) < need + maclen)
1121                 return SSH_MSG_NONE;
1122 #ifdef PACKET_DEBUG
1123         fprintf(stderr, "read_poll enc/full: ");
1124         buffer_dump(&input);
1125 #endif
1126         cp = buffer_append_space(&incoming_packet, need);
1127         cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1128         buffer_consume(&input, need);
1129         /*
1130          * compute MAC over seqnr and packet,
1131          * increment sequence number for incoming packet
1132          */
1133         if (mac && mac->enabled) {
1134                 macbuf = mac_compute(mac, p_read.seqnr,
1135                     buffer_ptr(&incoming_packet),
1136                     buffer_len(&incoming_packet));
1137                 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1138                         packet_disconnect("Corrupted MAC on input.");
1139                 DBG(debug("MAC #%d ok", p_read.seqnr));
1140                 buffer_consume(&input, mac->mac_len);
1141         }
1142         if (seqnr_p != NULL)
1143                 *seqnr_p = p_read.seqnr;
1144         if (++p_read.seqnr == 0)
1145                 logit("incoming seqnr wraps around");
1146         if (++p_read.packets == 0)
1147                 if (!(datafellows & SSH_BUG_NOREKEY))
1148                         fatal("XXX too many packets with same key");
1149         p_read.blocks += (packet_length + 4) / block_size;
1150
1151         /* get padlen */
1152         cp = buffer_ptr(&incoming_packet);
1153         padlen = cp[4];
1154         DBG(debug("input: padlen %d", padlen));
1155         if (padlen < 4)
1156                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1157
1158         /* skip packet size + padlen, discard padding */
1159         buffer_consume(&incoming_packet, 4 + 1);
1160         buffer_consume_end(&incoming_packet, padlen);
1161
1162         DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1163         if (comp && comp->enabled) {
1164                 buffer_clear(&compression_buffer);
1165                 buffer_uncompress(&incoming_packet, &compression_buffer);
1166                 buffer_clear(&incoming_packet);
1167                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1168                     buffer_len(&compression_buffer));
1169                 DBG(debug("input: len after de-compress %d",
1170                     buffer_len(&incoming_packet)));
1171         }
1172         /*
1173          * get packet type, implies consume.
1174          * return length of payload (without type field)
1175          */
1176         type = buffer_get_char(&incoming_packet);
1177         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1178                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1179         if (type == SSH2_MSG_NEWKEYS)
1180                 set_newkeys(MODE_IN);
1181         else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1182                 packet_enable_delayed_compress();
1183 #ifdef PACKET_DEBUG
1184         fprintf(stderr, "read/plain[%d]:\r\n", type);
1185         buffer_dump(&incoming_packet);
1186 #endif
1187         /* reset for next packet */
1188         packet_length = 0;
1189         return type;
1190 }
1191
1192 int
1193 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1194 {
1195         u_int reason, seqnr;
1196         u_char type;
1197         char *msg;
1198
1199         for (;;) {
1200                 if (compat20) {
1201                         type = packet_read_poll2(seqnr_p);
1202                         keep_alive_timeouts = 0;
1203                         if (type)
1204                                 DBG(debug("received packet type %d", type));
1205                         switch (type) {
1206                         case SSH2_MSG_IGNORE:
1207                                 debug3("Received SSH2_MSG_IGNORE");
1208                                 break;
1209                         case SSH2_MSG_DEBUG:
1210                                 packet_get_char();
1211                                 msg = packet_get_string(NULL);
1212                                 debug("Remote: %.900s", msg);
1213                                 xfree(msg);
1214                                 msg = packet_get_string(NULL);
1215                                 xfree(msg);
1216                                 break;
1217                         case SSH2_MSG_DISCONNECT:
1218                                 reason = packet_get_int();
1219                                 msg = packet_get_string(NULL);
1220                                 logit("Received disconnect from %s: %u: %.400s",
1221                                     get_remote_ipaddr(), reason, msg);
1222                                 xfree(msg);
1223                                 cleanup_exit(255);
1224                                 break;
1225                         case SSH2_MSG_UNIMPLEMENTED:
1226                                 seqnr = packet_get_int();
1227                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1228                                     seqnr);
1229                                 break;
1230                         default:
1231                                 return type;
1232                         }
1233                 } else {
1234                         type = packet_read_poll1();
1235                         switch (type) {
1236                         case SSH_MSG_IGNORE:
1237                                 break;
1238                         case SSH_MSG_DEBUG:
1239                                 msg = packet_get_string(NULL);
1240                                 debug("Remote: %.900s", msg);
1241                                 xfree(msg);
1242                                 break;
1243                         case SSH_MSG_DISCONNECT:
1244                                 msg = packet_get_string(NULL);
1245                                 logit("Received disconnect from %s: %.400s",
1246                                     get_remote_ipaddr(), msg);
1247                                 cleanup_exit(255);
1248                                 break;
1249                         default:
1250                                 if (type)
1251                                         DBG(debug("received packet type %d", type));
1252                                 return type;
1253                         }
1254                 }
1255         }
1256 }
1257
1258 int
1259 packet_read_poll(void)
1260 {
1261         return packet_read_poll_seqnr(NULL);
1262 }
1263
1264 /*
1265  * Buffers the given amount of input characters.  This is intended to be used
1266  * together with packet_read_poll.
1267  */
1268
1269 void
1270 packet_process_incoming(const char *buf, u_int len)
1271 {
1272         buffer_append(&input, buf, len);
1273 }
1274
1275 /* Returns a character from the packet. */
1276
1277 u_int
1278 packet_get_char(void)
1279 {
1280         char ch;
1281
1282         buffer_get(&incoming_packet, &ch, 1);
1283         return (u_char) ch;
1284 }
1285
1286 /* Returns an integer from the packet data. */
1287
1288 u_int
1289 packet_get_int(void)
1290 {
1291         return buffer_get_int(&incoming_packet);
1292 }
1293
1294 /*
1295  * Returns an arbitrary precision integer from the packet data.  The integer
1296  * must have been initialized before this call.
1297  */
1298
1299 void
1300 packet_get_bignum(BIGNUM * value)
1301 {
1302         buffer_get_bignum(&incoming_packet, value);
1303 }
1304
1305 void
1306 packet_get_bignum2(BIGNUM * value)
1307 {
1308         buffer_get_bignum2(&incoming_packet, value);
1309 }
1310
1311 void *
1312 packet_get_raw(u_int *length_ptr)
1313 {
1314         u_int bytes = buffer_len(&incoming_packet);
1315
1316         if (length_ptr != NULL)
1317                 *length_ptr = bytes;
1318         return buffer_ptr(&incoming_packet);
1319 }
1320
1321 int
1322 packet_remaining(void)
1323 {
1324         return buffer_len(&incoming_packet);
1325 }
1326
1327 /*
1328  * Returns a string from the packet data.  The string is allocated using
1329  * xmalloc; it is the responsibility of the calling program to free it when
1330  * no longer needed.  The length_ptr argument may be NULL, or point to an
1331  * integer into which the length of the string is stored.
1332  */
1333
1334 void *
1335 packet_get_string(u_int *length_ptr)
1336 {
1337         return buffer_get_string(&incoming_packet, length_ptr);
1338 }
1339
1340 /*
1341  * Sends a diagnostic message from the server to the client.  This message
1342  * can be sent at any time (but not while constructing another message). The
1343  * message is printed immediately, but only if the client is being executed
1344  * in verbose mode.  These messages are primarily intended to ease debugging
1345  * authentication problems.   The length of the formatted message must not
1346  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1347  */
1348
1349 void
1350 packet_send_debug(const char *fmt,...)
1351 {
1352         char buf[1024];
1353         va_list args;
1354
1355         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1356                 return;
1357
1358         va_start(args, fmt);
1359         vsnprintf(buf, sizeof(buf), fmt, args);
1360         va_end(args);
1361
1362         if (compat20) {
1363                 packet_start(SSH2_MSG_DEBUG);
1364                 packet_put_char(0);     /* bool: always display */
1365                 packet_put_cstring(buf);
1366                 packet_put_cstring("");
1367         } else {
1368                 packet_start(SSH_MSG_DEBUG);
1369                 packet_put_cstring(buf);
1370         }
1371         packet_send();
1372         packet_write_wait();
1373 }
1374
1375 /*
1376  * Logs the error plus constructs and sends a disconnect packet, closes the
1377  * connection, and exits.  This function never returns. The error message
1378  * should not contain a newline.  The length of the formatted message must
1379  * not exceed 1024 bytes.
1380  */
1381
1382 void
1383 packet_disconnect(const char *fmt,...)
1384 {
1385         char buf[1024];
1386         va_list args;
1387         static int disconnecting = 0;
1388
1389         if (disconnecting)      /* Guard against recursive invocations. */
1390                 fatal("packet_disconnect called recursively.");
1391         disconnecting = 1;
1392
1393         /*
1394          * Format the message.  Note that the caller must make sure the
1395          * message is of limited size.
1396          */
1397         va_start(args, fmt);
1398         vsnprintf(buf, sizeof(buf), fmt, args);
1399         va_end(args);
1400
1401         /* Display the error locally */
1402         logit("Disconnecting: %.100s", buf);
1403
1404         /* Send the disconnect message to the other side, and wait for it to get sent. */
1405         if (compat20) {
1406                 packet_start(SSH2_MSG_DISCONNECT);
1407                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1408                 packet_put_cstring(buf);
1409                 packet_put_cstring("");
1410         } else {
1411                 packet_start(SSH_MSG_DISCONNECT);
1412                 packet_put_cstring(buf);
1413         }
1414         packet_send();
1415         packet_write_wait();
1416
1417         /* Stop listening for connections. */
1418         channel_close_all();
1419
1420         /* Close the connection. */
1421         packet_close();
1422         cleanup_exit(255);
1423 }
1424
1425 /* Checks if there is any buffered output, and tries to write some of the output. */
1426
1427 int
1428 packet_write_poll(void)
1429 {
1430         int len = 0;
1431         len = buffer_len(&output);
1432
1433         if (len > 0) {
1434                 len = write(connection_out, buffer_ptr(&output), len);
1435                 if (len <= 0) {
1436                         if (errno == EAGAIN)
1437                           return (0);
1438                         else
1439                                 fatal("Write failed: %.100s", strerror(errno));
1440                 }
1441                 buffer_consume(&output, len);
1442         }
1443         return(len);
1444 }
1445
1446 /*
1447  * Calls packet_write_poll repeatedly until all pending output data has been
1448  * written.
1449  */
1450
1451 int
1452 packet_write_wait(void)
1453 {
1454         fd_set *setp;
1455         u_int bytes_sent = 0;
1456
1457         setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1458             sizeof(fd_mask));
1459         bytes_sent += packet_write_poll();
1460         while (packet_have_data_to_write()) {
1461                 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1462                     sizeof(fd_mask));
1463                 FD_SET(connection_out, setp);
1464                 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1465                     (errno == EAGAIN || errno == EINTR))
1466                         ;
1467                 bytes_sent += packet_write_poll();
1468         }
1469         xfree(setp);
1470         return (bytes_sent);
1471 }
1472
1473 /* Returns true if there is buffered data to write to the connection. */
1474
1475 int
1476 packet_have_data_to_write(void)
1477 {
1478         return buffer_len(&output) != 0;
1479 }
1480
1481 /* Returns true if there is not too much data to write to the connection. */
1482
1483 int
1484 packet_not_very_much_data_to_write(void)
1485 {
1486         if (interactive_mode)
1487                 return buffer_len(&output) < 16384;
1488         else
1489                 return buffer_len(&output) < 128 * 1024;
1490 }
1491
1492
1493 static void
1494 packet_set_tos(int interactive)
1495 {
1496 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1497         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1498
1499         if (!packet_connection_is_on_socket() ||
1500             !packet_connection_is_ipv4())
1501                 return;
1502         if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1503             sizeof(tos)) < 0)
1504                 error("setsockopt IP_TOS %d: %.100s:",
1505                     tos, strerror(errno));
1506 #endif
1507 }
1508
1509 /* Informs that the current session is interactive.  Sets IP flags for that. */
1510
1511 void
1512 packet_set_interactive(int interactive)
1513 {
1514         static int called = 0;
1515
1516         if (called)
1517                 return;
1518         called = 1;
1519
1520         /* Record that we are in interactive mode. */
1521         interactive_mode = interactive;
1522
1523         /* Only set socket options if using a socket.  */
1524         if (!packet_connection_is_on_socket())
1525                 return;
1526         set_nodelay(connection_in);
1527         packet_set_tos(interactive);
1528 }
1529
1530 /* Returns true if the current connection is interactive. */
1531
1532 int
1533 packet_is_interactive(void)
1534 {
1535         return interactive_mode;
1536 }
1537
1538 int
1539 packet_set_maxsize(u_int s)
1540 {
1541         static int called = 0;
1542
1543         if (called) {
1544                 logit("packet_set_maxsize: called twice: old %d new %d",
1545                     max_packet_size, s);
1546                 return -1;
1547         }
1548         if (s < 4 * 1024 || s > 1024 * 1024) {
1549                 logit("packet_set_maxsize: bad size %d", s);
1550                 return -1;
1551         }
1552         called = 1;
1553         debug("packet_set_maxsize: setting to %d", s);
1554         max_packet_size = s;
1555         return s;
1556 }
1557
1558 /* roundup current message to pad bytes */
1559 void
1560 packet_add_padding(u_char pad)
1561 {
1562         extra_pad = pad;
1563 }
1564
1565 /*
1566  * 9.2.  Ignored Data Message
1567  *
1568  *   byte      SSH_MSG_IGNORE
1569  *   string    data
1570  *
1571  * All implementations MUST understand (and ignore) this message at any
1572  * time (after receiving the protocol version). No implementation is
1573  * required to send them. This message can be used as an additional
1574  * protection measure against advanced traffic analysis techniques.
1575  */
1576 void
1577 packet_send_ignore(int nbytes)
1578 {
1579         u_int32_t rnd = 0;
1580         int i;
1581
1582         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1583         packet_put_int(nbytes);
1584         for (i = 0; i < nbytes; i++) {
1585                 if (i % 4 == 0)
1586                         rnd = arc4random();
1587                 packet_put_char((u_char)rnd & 0xff);
1588                 rnd >>= 8;
1589         }
1590 }
1591
1592 int rekey_requested = 0;
1593 void
1594 packet_request_rekeying(void)
1595 {
1596         rekey_requested = 1;
1597 }
1598
1599 #define MAX_PACKETS     (1U<<31)
1600 int
1601 packet_need_rekeying(void)
1602 {
1603         if (datafellows & SSH_BUG_NOREKEY)
1604                 return 0;
1605         if (rekey_requested == 1)
1606         {
1607                 rekey_requested = 0;
1608                 return 1;
1609         }
1610         return
1611             (p_send.packets > MAX_PACKETS) ||
1612             (p_read.packets > MAX_PACKETS) ||
1613             (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1614             (max_blocks_in  && (p_read.blocks > max_blocks_in));
1615 }
1616
1617 void
1618 packet_set_rekey_limit(u_int32_t bytes)
1619 {
1620         rekey_limit = bytes;
1621 }
1622
1623 void
1624 packet_set_server(void)
1625 {
1626         server_side = 1;
1627 }
1628
1629 void
1630 packet_set_authenticated(void)
1631 {
1632         after_authentication = 1;
1633 }
1634
1635 int
1636 packet_authentication_state(void)
1637 {
1638         return(after_authentication);
1639 }