crypto/openssh-4/packet.c

   1 /* $OpenBSD: packet.c,v 1.145 2006/09/19 21:14:08 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_systm.h>
  51 #include <netinet/in.h>
  52 #include <netinet/ip.h>
  53 #include <arpa/inet.h>
  54
  55 #include <errno.h>
  56 #include <stdarg.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <unistd.h>
  61 #include <signal.h>
  62
  63 #include "xmalloc.h"
  64 #include "buffer.h"
  65 #include "packet.h"
  66 #include "crc32.h"
  67 #include "compress.h"
  68 #include "deattack.h"
  69 #include "channels.h"
  70 #include "compat.h"
  71 #include "ssh1.h"
  72 #include "ssh2.h"
  73 #include "cipher.h"
  74 #include "key.h"
  75 #include "kex.h"
  76 #include "mac.h"
  77 #include "log.h"
  78 #include "canohost.h"
  79 #include "misc.h"
  80 #include "ssh.h"
  81
  82 #ifdef PACKET_DEBUG
  83 #define DBG(x) x
  84 #else
  85 #define DBG(x)
  86 #endif
  87
  88 /*
  89  * This variable contains the file descriptors used for communicating with
  90  * the other side.  connection_in is used for reading; connection_out for
  91  * writing.  These can be the same descriptor, in which case it is assumed to
  92  * be a socket.
  93  */
  94 static int connection_in = -1;
  95 static int connection_out = -1;
  96
  97 /* Protocol flags for the remote side. */
  98 static u_int remote_protocol_flags = 0;
  99
 100 /* Encryption context for receiving data.  This is only used for decryption. */
 101 static CipherContext receive_context;
 102
 103 /* Encryption context for sending data.  This is only used for encryption. */
 104 static CipherContext send_context;
 105
 106 /* Buffer for raw input data from the socket. */
 107 Buffer input;
 108
 109 /* Buffer for raw output data going to the socket. */
 110 Buffer output;
 111
 112 /* Buffer for the partial outgoing packet being constructed. */
 113 static Buffer outgoing_packet;
 114
 115 /* Buffer for the incoming packet currently being processed. */
 116 static Buffer incoming_packet;
 117
 118 /* Scratch buffer for packet compression/decompression. */
 119 static Buffer compression_buffer;
 120 static int compression_buffer_ready = 0;
 121
 122 /* Flag indicating whether packet compression/decompression is enabled. */
 123 static int packet_compression = 0;
 124
 125 /* default maximum packet size */
 126 u_int max_packet_size = 32768;
 127
 128 /* Flag indicating whether this module has been initialized. */
 129 static int initialized = 0;
 130
 131 /* Set to true if the connection is interactive. */
 132 static int interactive_mode = 0;
 133
 134 /* Set to true if we are the server side. */
 135 static int server_side = 0;
 136
 137 /* Set to true if we are authenticated. */
 138 static int after_authentication = 0;
 139
 140 /* Session key information for Encryption and MAC */
 141 Newkeys *newkeys[MODE_MAX];
 142 static struct packet_state {
 143         u_int32_t seqnr;
 144         u_int32_t packets;
 145         u_int64_t blocks;
 146 } p_read, p_send;
 147
 148 static u_int64_t max_blocks_in, max_blocks_out;
 149 static u_int32_t rekey_limit;
 150
 151 /* Session key for protocol v1 */
 152 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 153 static u_int ssh1_keylen;
 154
 155 /* roundup current message to extra_pad bytes */
 156 static u_char extra_pad = 0;
 157
 158 struct packet {
 159         TAILQ_ENTRY(packet) next;
 160         u_char type;
 161         Buffer payload;
 162 };
 163 TAILQ_HEAD(, packet) outgoing;
 164
 165 /*
 166  * Sets the descriptors used for communication.  Disables encryption until
 167  * packet_set_encryption_key is called.
 168  */
 169 void
 170 packet_set_connection(int fd_in, int fd_out)
 171 {
 172         Cipher *none = cipher_by_name("none");
 173
 174         if (none == NULL)
 175                 fatal("packet_set_connection: cannot load cipher 'none'");
 176         connection_in = fd_in;
 177         connection_out = fd_out;
 178         cipher_init(&send_context, none, (const u_char *)"",
 179             0, NULL, 0, CIPHER_ENCRYPT);
 180         cipher_init(&receive_context, none, (const u_char *)"",
 181             0, NULL, 0, CIPHER_DECRYPT);
 182         newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
 183         if (!initialized) {
 184                 initialized = 1;
 185                 buffer_init(&input);
 186                 buffer_init(&output);
 187                 buffer_init(&outgoing_packet);
 188                 buffer_init(&incoming_packet);
 189                 TAILQ_INIT(&outgoing);
 190         }
 191 }
 192
 193 /* Returns 1 if remote host is connected via socket, 0 if not. */
 194
 195 int
 196 packet_connection_is_on_socket(void)
 197 {
 198         struct sockaddr_storage from, to;
 199         socklen_t fromlen, tolen;
 200
 201         /* filedescriptors in and out are the same, so it's a socket */
 202         if (connection_in == connection_out)
 203                 return 1;
 204         fromlen = sizeof(from);
 205         memset(&from, 0, sizeof(from));
 206         if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
 207                 return 0;
 208         tolen = sizeof(to);
 209         memset(&to, 0, sizeof(to));
 210         if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
 211                 return 0;
 212         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 213                 return 0;
 214         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 215                 return 0;
 216         return 1;
 217 }
 218
 219 /*
 220  * Exports an IV from the CipherContext required to export the key
 221  * state back from the unprivileged child to the privileged parent
 222  * process.
 223  */
 224
 225 void
 226 packet_get_keyiv(int mode, u_char *iv, u_int len)
 227 {
 228         CipherContext *cc;
 229
 230         if (mode == MODE_OUT)
 231                 cc = &send_context;
 232         else
 233                 cc = &receive_context;
 234
 235         cipher_get_keyiv(cc, iv, len);
 236 }
 237
 238 int
 239 packet_get_keycontext(int mode, u_char *dat)
 240 {
 241         CipherContext *cc;
 242
 243         if (mode == MODE_OUT)
 244                 cc = &send_context;
 245         else
 246                 cc = &receive_context;
 247
 248         return (cipher_get_keycontext(cc, dat));
 249 }
 250
 251 void
 252 packet_set_keycontext(int mode, u_char *dat)
 253 {
 254         CipherContext *cc;
 255
 256         if (mode == MODE_OUT)
 257                 cc = &send_context;
 258         else
 259                 cc = &receive_context;
 260
 261         cipher_set_keycontext(cc, dat);
 262 }
 263
 264 int
 265 packet_get_keyiv_len(int mode)
 266 {
 267         CipherContext *cc;
 268
 269         if (mode == MODE_OUT)
 270                 cc = &send_context;
 271         else
 272                 cc = &receive_context;
 273
 274         return (cipher_get_keyiv_len(cc));
 275 }
 276
 277 void
 278 packet_set_iv(int mode, u_char *dat)
 279 {
 280         CipherContext *cc;
 281
 282         if (mode == MODE_OUT)
 283                 cc = &send_context;
 284         else
 285                 cc = &receive_context;
 286
 287         cipher_set_keyiv(cc, dat);
 288 }
 289
 290 int
 291 packet_get_ssh1_cipher(void)
 292 {
 293         return (cipher_get_number(receive_context.cipher));
 294 }
 295
 296 void
 297 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets)
 298 {
 299         struct packet_state *state;
 300
 301         state = (mode == MODE_IN) ? &p_read : &p_send;
 302         *seqnr = state->seqnr;
 303         *blocks = state->blocks;
 304         *packets = state->packets;
 305 }
 306
 307 void
 308 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets)
 309 {
 310         struct packet_state *state;
 311
 312         state = (mode == MODE_IN) ? &p_read : &p_send;
 313         state->seqnr = seqnr;
 314         state->blocks = blocks;
 315         state->packets = packets;
 316 }
 317
 318 /* returns 1 if connection is via ipv4 */
 319
 320 int
 321 packet_connection_is_ipv4(void)
 322 {
 323         struct sockaddr_storage to;
 324         socklen_t tolen = sizeof(to);
 325
 326         memset(&to, 0, sizeof(to));
 327         if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
 328                 return 0;
 329         if (to.ss_family == AF_INET)
 330                 return 1;
 331 #ifdef IPV4_IN_IPV6
 332         if (to.ss_family == AF_INET6 &&
 333             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 334                 return 1;
 335 #endif
 336         return 0;
 337 }
 338
 339 /* Sets the connection into non-blocking mode. */
 340
 341 void
 342 packet_set_nonblocking(void)
 343 {
 344         /* Set the socket into non-blocking mode. */
 345         set_nonblock(connection_in);
 346
 347         if (connection_out != connection_in)
 348                 set_nonblock(connection_out);
 349 }
 350
 351 /* Returns the socket used for reading. */
 352
 353 int
 354 packet_get_connection_in(void)
 355 {
 356         return connection_in;
 357 }
 358
 359 /* Returns the descriptor used for writing. */
 360
 361 int
 362 packet_get_connection_out(void)
 363 {
 364         return connection_out;
 365 }
 366
 367 /* Closes the connection and clears and frees internal data structures. */
 368
 369 void
 370 packet_close(void)
 371 {
 372         if (!initialized)
 373                 return;
 374         initialized = 0;
 375         if (connection_in == connection_out) {
 376                 shutdown(connection_out, SHUT_RDWR);
 377                 close(connection_out);
 378         } else {
 379                 close(connection_in);
 380                 close(connection_out);
 381         }
 382         buffer_free(&input);
 383         buffer_free(&output);
 384         buffer_free(&outgoing_packet);
 385         buffer_free(&incoming_packet);
 386         if (compression_buffer_ready) {
 387                 buffer_free(&compression_buffer);
 388                 buffer_compress_uninit();
 389         }
 390         cipher_cleanup(&send_context);
 391         cipher_cleanup(&receive_context);
 392 }
 393
 394 /* Sets remote side protocol flags. */
 395
 396 void
 397 packet_set_protocol_flags(u_int protocol_flags)
 398 {
 399         remote_protocol_flags = protocol_flags;
 400 }
 401
 402 /* Returns the remote protocol flags set earlier by the above function. */
 403
 404 u_int
 405 packet_get_protocol_flags(void)
 406 {
 407         return remote_protocol_flags;
 408 }
 409
 410 /*
 411  * Starts packet compression from the next packet on in both directions.
 412  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 413  */
 414
 415 static void
 416 packet_init_compression(void)
 417 {
 418         if (compression_buffer_ready == 1)
 419                 return;
 420         compression_buffer_ready = 1;
 421         buffer_init(&compression_buffer);
 422 }
 423
 424 void
 425 packet_start_compression(int level)
 426 {
 427         if (packet_compression && !compat20)
 428                 fatal("Compression already enabled.");
 429         packet_compression = 1;
 430         packet_init_compression();
 431         buffer_compress_init_send(level);
 432         buffer_compress_init_recv();
 433 }
 434
 435 /*
 436  * Causes any further packets to be encrypted using the given key.  The same
 437  * key is used for both sending and reception.  However, both directions are
 438  * encrypted independently of each other.
 439  */
 440
 441 void
 442 packet_set_encryption_key(const u_char *key, u_int keylen,
 443     int number)
 444 {
 445         Cipher *cipher = cipher_by_number(number);
 446
 447         if (cipher == NULL)
 448                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 449         if (keylen < 20)
 450                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 451         if (keylen > SSH_SESSION_KEY_LENGTH)
 452                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 453         memcpy(ssh1_key, key, keylen);
 454         ssh1_keylen = keylen;
 455         cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
 456         cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
 457 }
 458
 459 u_int
 460 packet_get_encryption_key(u_char *key)
 461 {
 462         if (key == NULL)
 463                 return (ssh1_keylen);
 464         memcpy(key, ssh1_key, ssh1_keylen);
 465         return (ssh1_keylen);
 466 }
 467
 468 /* Start constructing a packet to send. */
 469 void
 470 packet_start(u_char type)
 471 {
 472         u_char buf[9];
 473         int len;
 474
 475         DBG(debug("packet_start[%d]", type));
 476         len = compat20 ? 6 : 9;
 477         memset(buf, 0, len - 1);
 478         buf[len - 1] = type;
 479         buffer_clear(&outgoing_packet);
 480         buffer_append(&outgoing_packet, buf, len);
 481 }
 482
 483 /* Append payload. */
 484 void
 485 packet_put_char(int value)
 486 {
 487         char ch = value;
 488
 489         buffer_append(&outgoing_packet, &ch, 1);
 490 }
 491
 492 void
 493 packet_put_int(u_int value)
 494 {
 495         buffer_put_int(&outgoing_packet, value);
 496 }
 497
 498 void
 499 packet_put_string(const void *buf, u_int len)
 500 {
 501         buffer_put_string(&outgoing_packet, buf, len);
 502 }
 503
 504 void
 505 packet_put_cstring(const char *str)
 506 {
 507         buffer_put_cstring(&outgoing_packet, str);
 508 }
 509
 510 void
 511 packet_put_raw(const void *buf, u_int len)
 512 {
 513         buffer_append(&outgoing_packet, buf, len);
 514 }
 515
 516 void
 517 packet_put_bignum(BIGNUM * value)
 518 {
 519         buffer_put_bignum(&outgoing_packet, value);
 520 }
 521
 522 void
 523 packet_put_bignum2(BIGNUM * value)
 524 {
 525         buffer_put_bignum2(&outgoing_packet, value);
 526 }
 527
 528 /*
 529  * Finalizes and sends the packet.  If the encryption key has been set,
 530  * encrypts the packet before sending.
 531  */
 532
 533 static void
 534 packet_send1(void)
 535 {
 536         u_char buf[8], *cp;
 537         int i, padding, len;
 538         u_int checksum;
 539         u_int32_t rnd = 0;
 540
 541         /*
 542          * If using packet compression, compress the payload of the outgoing
 543          * packet.
 544          */
 545         if (packet_compression) {
 546                 buffer_clear(&compression_buffer);
 547                 /* Skip padding. */
 548                 buffer_consume(&outgoing_packet, 8);
 549                 /* padding */
 550                 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
 551                 buffer_compress(&outgoing_packet, &compression_buffer);
 552                 buffer_clear(&outgoing_packet);
 553                 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
 554                     buffer_len(&compression_buffer));
 555         }
 556         /* Compute packet length without padding (add checksum, remove padding). */
 557         len = buffer_len(&outgoing_packet) + 4 - 8;
 558
 559         /* Insert padding. Initialized to zero in packet_start1() */
 560         padding = 8 - len % 8;
 561         if (!send_context.plaintext) {
 562                 cp = buffer_ptr(&outgoing_packet);
 563                 for (i = 0; i < padding; i++) {
 564                         if (i % 4 == 0)
 565                                 rnd = arc4random();
 566                         cp[7 - i] = rnd & 0xff;
 567                         rnd >>= 8;
 568                 }
 569         }
 570         buffer_consume(&outgoing_packet, 8 - padding);
 571
 572         /* Add check bytes. */
 573         checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
 574             buffer_len(&outgoing_packet));
 575         put_u32(buf, checksum);
 576         buffer_append(&outgoing_packet, buf, 4);
 577
 578 #ifdef PACKET_DEBUG
 579         fprintf(stderr, "packet_send plain: ");
 580         buffer_dump(&outgoing_packet);
 581 #endif
 582
 583         /* Append to output. */
 584         put_u32(buf, len);
 585         buffer_append(&output, buf, 4);
 586         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
 587         cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
 588             buffer_len(&outgoing_packet));
 589
 590 #ifdef PACKET_DEBUG
 591         fprintf(stderr, "encrypted: ");
 592         buffer_dump(&output);
 593 #endif
 594
 595         buffer_clear(&outgoing_packet);
 596
 597         /*
 598          * Note that the packet is now only buffered in output.  It won't be
 599          * actually sent until packet_write_wait or packet_write_poll is
 600          * called.
 601          */
 602 }
 603
 604 void
 605 set_newkeys(int mode)
 606 {
 607         Enc *enc;
 608         Mac *mac;
 609         Comp *comp;
 610         CipherContext *cc;
 611         u_int64_t *max_blocks;
 612         int crypt_type;
 613
 614         debug2("set_newkeys: mode %d", mode);
 615
 616         if (mode == MODE_OUT) {
 617                 cc = &send_context;
 618                 crypt_type = CIPHER_ENCRYPT;
 619                 p_send.packets = p_send.blocks = 0;
 620                 max_blocks = &max_blocks_out;
 621         } else {
 622                 cc = &receive_context;
 623                 crypt_type = CIPHER_DECRYPT;
 624                 p_read.packets = p_read.blocks = 0;
 625                 max_blocks = &max_blocks_in;
 626         }
 627         if (newkeys[mode] != NULL) {
 628                 debug("set_newkeys: rekeying");
 629                 cipher_cleanup(cc);
 630                 enc  = &newkeys[mode]->enc;
 631                 mac  = &newkeys[mode]->mac;
 632                 comp = &newkeys[mode]->comp;
 633                 memset(mac->key, 0, mac->key_len);
 634                 xfree(enc->name);
 635                 xfree(enc->iv);
 636                 xfree(enc->key);
 637                 xfree(mac->name);
 638                 xfree(mac->key);
 639                 xfree(comp->name);
 640                 xfree(newkeys[mode]);
 641         }
 642         newkeys[mode] = kex_get_newkeys(mode);
 643         if (newkeys[mode] == NULL)
 644                 fatal("newkeys: no keys for mode %d", mode);
 645         enc  = &newkeys[mode]->enc;
 646         mac  = &newkeys[mode]->mac;
 647         comp = &newkeys[mode]->comp;
 648         if (mac->md != NULL)
 649                 mac->enabled = 1;
 650         DBG(debug("cipher_init_context: %d", mode));
 651         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 652             enc->iv, enc->block_size, crypt_type);
 653         /* Deleting the keys does not gain extra security */
 654         /* memset(enc->iv,  0, enc->block_size);
 655            memset(enc->key, 0, enc->key_len); */
 656         if ((comp->type == COMP_ZLIB ||
 657             (comp->type == COMP_DELAYED && after_authentication)) &&
 658             comp->enabled == 0) {
 659                 packet_init_compression();
 660                 if (mode == MODE_OUT)
 661                         buffer_compress_init_send(6);
 662                 else
 663                         buffer_compress_init_recv();
 664                 comp->enabled = 1;
 665         }
 666         /*
 667          * The 2^(blocksize*2) limit is too expensive for 3DES,
 668          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 669          */
 670         if (enc->block_size >= 16)
 671                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 672         else
 673                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 674         if (rekey_limit)
 675                 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
 676 }
 677
 678 /*
 679  * Delayed compression for SSH2 is enabled after authentication:
 680  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 681  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 682  */
 683 static void
 684 packet_enable_delayed_compress(void)
 685 {
 686         Comp *comp = NULL;
 687         int mode;
 688
 689         /*
 690          * Remember that we are past the authentication step, so rekeying
 691          * with COMP_DELAYED will turn on compression immediately.
 692          */
 693         after_authentication = 1;
 694         for (mode = 0; mode < MODE_MAX; mode++) {
 695                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 696                 if (newkeys[mode] == NULL)
 697                         continue;
 698                 comp = &newkeys[mode]->comp;
 699                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 700                         packet_init_compression();
 701                         if (mode == MODE_OUT)
 702                                 buffer_compress_init_send(6);
 703                         else
 704                                 buffer_compress_init_recv();
 705                         comp->enabled = 1;
 706                 }
 707         }
 708 }
 709
 710 /*
 711  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 712  */
 713 static void
 714 packet_send2_wrapped(void)
 715 {
 716         u_char type, *cp, *macbuf = NULL;
 717         u_char padlen, pad;
 718         u_int packet_length = 0;
 719         u_int i, len;
 720         u_int32_t rnd = 0;
 721         Enc *enc   = NULL;
 722         Mac *mac   = NULL;
 723         Comp *comp = NULL;
 724         int block_size;
 725
 726         if (newkeys[MODE_OUT] != NULL) {
 727                 enc  = &newkeys[MODE_OUT]->enc;
 728                 mac  = &newkeys[MODE_OUT]->mac;
 729                 comp = &newkeys[MODE_OUT]->comp;
 730         }
 731         block_size = enc ? enc->block_size : 8;
 732
 733         cp = buffer_ptr(&outgoing_packet);
 734         type = cp[5];
 735
 736 #ifdef PACKET_DEBUG
 737         fprintf(stderr, "plain:     ");
 738         buffer_dump(&outgoing_packet);
 739 #endif
 740
 741         if (comp && comp->enabled) {
 742                 len = buffer_len(&outgoing_packet);
 743                 /* skip header, compress only payload */
 744                 buffer_consume(&outgoing_packet, 5);
 745                 buffer_clear(&compression_buffer);
 746                 buffer_compress(&outgoing_packet, &compression_buffer);
 747                 buffer_clear(&outgoing_packet);
 748                 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
 749                 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
 750                     buffer_len(&compression_buffer));
 751                 DBG(debug("compression: raw %d compressed %d", len,
 752                     buffer_len(&outgoing_packet)));
 753         }
 754
 755         /* sizeof (packet_len + pad_len + payload) */
 756         len = buffer_len(&outgoing_packet);
 757
 758         /*
 759          * calc size of padding, alloc space, get random data,
 760          * minimum padding is 4 bytes
 761          */
 762         padlen = block_size - (len % block_size);
 763         if (padlen < 4)
 764                 padlen += block_size;
 765         if (extra_pad) {
 766                 /* will wrap if extra_pad+padlen > 255 */
 767                 extra_pad  = roundup(extra_pad, block_size);
 768                 pad = extra_pad - ((len + padlen) % extra_pad);
 769                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 770                     pad, len, padlen, extra_pad);
 771                 padlen += pad;
 772                 extra_pad = 0;
 773         }
 774         cp = buffer_append_space(&outgoing_packet, padlen);
 775         if (enc && !send_context.plaintext) {
 776                 /* random padding */
 777                 for (i = 0; i < padlen; i++) {
 778                         if (i % 4 == 0)
 779                                 rnd = arc4random();
 780                         cp[i] = rnd & 0xff;
 781                         rnd >>= 8;
 782                 }
 783         } else {
 784                 /* clear padding */
 785                 memset(cp, 0, padlen);
 786         }
 787         /* packet_length includes payload, padding and padding length field */
 788         packet_length = buffer_len(&outgoing_packet) - 4;
 789         cp = buffer_ptr(&outgoing_packet);
 790         put_u32(cp, packet_length);
 791         cp[4] = padlen;
 792         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 793
 794         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 795         if (mac && mac->enabled) {
 796                 macbuf = mac_compute(mac, p_send.seqnr,
 797                     buffer_ptr(&outgoing_packet),
 798                     buffer_len(&outgoing_packet));
 799                 DBG(debug("done calc MAC out #%d", p_send.seqnr));
 800         }
 801         /* encrypt packet and append to output buffer. */
 802         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
 803         cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
 804             buffer_len(&outgoing_packet));
 805         /* append unencrypted MAC */
 806         if (mac && mac->enabled)
 807                 buffer_append(&output, macbuf, mac->mac_len);
 808 #ifdef PACKET_DEBUG
 809         fprintf(stderr, "encrypted: ");
 810         buffer_dump(&output);
 811 #endif
 812         /* increment sequence number for outgoing packets */
 813         if (++p_send.seqnr == 0)
 814                 logit("outgoing seqnr wraps around");
 815         if (++p_send.packets == 0)
 816                 if (!(datafellows & SSH_BUG_NOREKEY))
 817                         fatal("XXX too many packets with same key");
 818         p_send.blocks += (packet_length + 4) / block_size;
 819         buffer_clear(&outgoing_packet);
 820
 821         if (type == SSH2_MSG_NEWKEYS)
 822                 set_newkeys(MODE_OUT);
 823         else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
 824                 packet_enable_delayed_compress();
 825 }
 826
 827 static void
 828 packet_send2(void)
 829 {
 830         static int rekeying = 0;
 831         struct packet *p;
 832         u_char type, *cp;
 833
 834         cp = buffer_ptr(&outgoing_packet);
 835         type = cp[5];
 836
 837         /* during rekeying we can only send key exchange messages */
 838         if (rekeying) {
 839                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 840                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 841                         debug("enqueue packet: %u", type);
 842                         p = xmalloc(sizeof(*p));
 843                         p->type = type;
 844                         memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
 845                         buffer_init(&outgoing_packet);
 846                         TAILQ_INSERT_TAIL(&outgoing, p, next);
 847                         return;
 848                 }
 849         }
 850
 851         /* rekeying starts with sending KEXINIT */
 852         if (type == SSH2_MSG_KEXINIT)
 853                 rekeying = 1;
 854
 855         packet_send2_wrapped();
 856
 857         /* after a NEWKEYS message we can send the complete queue */
 858         if (type == SSH2_MSG_NEWKEYS) {
 859                 rekeying = 0;
 860                 while ((p = TAILQ_FIRST(&outgoing))) {
 861                         type = p->type;
 862                         debug("dequeue packet: %u", type);
 863                         buffer_free(&outgoing_packet);
 864                         memcpy(&outgoing_packet, &p->payload,
 865                             sizeof(Buffer));
 866                         TAILQ_REMOVE(&outgoing, p, next);
 867                         xfree(p);
 868                         packet_send2_wrapped();
 869                 }
 870         }
 871 }
 872
 873 void
 874 packet_send(void)
 875 {
 876         if (compat20)
 877                 packet_send2();
 878         else
 879                 packet_send1();
 880         DBG(debug("packet_send done"));
 881 }
 882
 883 /*
 884  * Waits until a packet has been received, and returns its type.  Note that
 885  * no other data is processed until this returns, so this function should not
 886  * be used during the interactive session.
 887  */
 888
 889 int
 890 packet_read_seqnr(u_int32_t *seqnr_p)
 891 {
 892         int type, len;
 893         fd_set *setp;
 894         char buf[8192];
 895         DBG(debug("packet_read()"));
 896
 897         setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
 898             sizeof(fd_mask));
 899
 900         /* Since we are blocking, ensure that all written packets have been sent. */
 901         packet_write_wait();
 902
 903         /* Stay in the loop until we have received a complete packet. */
 904         for (;;) {
 905                 /* Try to read a packet from the buffer. */
 906                 type = packet_read_poll_seqnr(seqnr_p);
 907                 if (!compat20 && (
 908                     type == SSH_SMSG_SUCCESS
 909                     || type == SSH_SMSG_FAILURE
 910                     || type == SSH_CMSG_EOF
 911                     || type == SSH_CMSG_EXIT_CONFIRMATION))
 912                         packet_check_eom();
 913                 /* If we got a packet, return it. */
 914                 if (type != SSH_MSG_NONE) {
 915                         xfree(setp);
 916                         return type;
 917                 }
 918                 /*
 919                  * Otherwise, wait for some data to arrive, add it to the
 920                  * buffer, and try again.
 921                  */
 922                 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
 923                     sizeof(fd_mask));
 924                 FD_SET(connection_in, setp);
 925
 926                 /* Wait for some data to arrive. */
 927                 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
 928                     (errno == EAGAIN || errno == EINTR))
 929                         ;
 930
 931                 /* Read data from the socket. */
 932                 len = read(connection_in, buf, sizeof(buf));
 933                 if (len == 0) {
 934                         logit("Connection closed by %.200s", get_remote_ipaddr());
 935                         cleanup_exit(255);
 936                 }
 937                 if (len < 0)
 938                         fatal("Read from socket failed: %.100s", strerror(errno));
 939                 /* Append it to the buffer. */
 940                 packet_process_incoming(buf, len);
 941         }
 942         /* NOTREACHED */
 943 }
 944
 945 int
 946 packet_read(void)
 947 {
 948         return packet_read_seqnr(NULL);
 949 }
 950
 951 /*
 952  * Waits until a packet has been received, verifies that its type matches
 953  * that given, and gives a fatal error and exits if there is a mismatch.
 954  */
 955
 956 void
 957 packet_read_expect(int expected_type)
 958 {
 959         int type;
 960
 961         type = packet_read();
 962         if (type != expected_type)
 963                 packet_disconnect("Protocol error: expected packet type %d, got %d",
 964                     expected_type, type);
 965 }
 966
 967 /* Checks if a full packet is available in the data received so far via
 968  * packet_process_incoming.  If so, reads the packet; otherwise returns
 969  * SSH_MSG_NONE.  This does not wait for data from the connection.
 970  *
 971  * SSH_MSG_DISCONNECT is handled specially here.  Also,
 972  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
 973  * to higher levels.
 974  */
 975
 976 static int
 977 packet_read_poll1(void)
 978 {
 979         u_int len, padded_len;
 980         u_char *cp, type;
 981         u_int checksum, stored_checksum;
 982
 983         /* Check if input size is less than minimum packet size. */
 984         if (buffer_len(&input) < 4 + 8)
 985                 return SSH_MSG_NONE;
 986         /* Get length of incoming packet. */
 987         cp = buffer_ptr(&input);
 988         len = get_u32(cp);
 989         if (len < 1 + 2 + 2 || len > 256 * 1024)
 990                 packet_disconnect("Bad packet length %u.", len);
 991         padded_len = (len + 8) & ~7;
 992
 993         /* Check if the packet has been entirely received. */
 994         if (buffer_len(&input) < 4 + padded_len)
 995                 return SSH_MSG_NONE;
 996
 997         /* The entire packet is in buffer. */
 998
 999         /* Consume packet length. */
1000         buffer_consume(&input, 4);
1001
1002         /*
1003          * Cryptographic attack detector for ssh
1004          * (C)1998 CORE-SDI, Buenos Aires Argentina
1005          * Ariel Futoransky(futo@core-sdi.com)
1006          */
1007         if (!receive_context.plaintext) {
1008                 switch (detect_attack(buffer_ptr(&input), padded_len)) {
1009                 case DEATTACK_DETECTED:
1010                         packet_disconnect("crc32 compensation attack: "
1011                             "network attack detected");
1012                 case DEATTACK_DOS_DETECTED:
1013                         packet_disconnect("deattack denial of "
1014                             "service detected");
1015                 }
1016         }
1017
1018         /* Decrypt data to incoming_packet. */
1019         buffer_clear(&incoming_packet);
1020         cp = buffer_append_space(&incoming_packet, padded_len);
1021         cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1022
1023         buffer_consume(&input, padded_len);
1024
1025 #ifdef PACKET_DEBUG
1026         fprintf(stderr, "read_poll plain: ");
1027         buffer_dump(&incoming_packet);
1028 #endif
1029
1030         /* Compute packet checksum. */
1031         checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1032             buffer_len(&incoming_packet) - 4);
1033
1034         /* Skip padding. */
1035         buffer_consume(&incoming_packet, 8 - len % 8);
1036
1037         /* Test check bytes. */
1038         if (len != buffer_len(&incoming_packet))
1039                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1040                     len, buffer_len(&incoming_packet));
1041
1042         cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1043         stored_checksum = get_u32(cp);
1044         if (checksum != stored_checksum)
1045                 packet_disconnect("Corrupted check bytes on input.");
1046         buffer_consume_end(&incoming_packet, 4);
1047
1048         if (packet_compression) {
1049                 buffer_clear(&compression_buffer);
1050                 buffer_uncompress(&incoming_packet, &compression_buffer);
1051                 buffer_clear(&incoming_packet);
1052                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1053                     buffer_len(&compression_buffer));
1054         }
1055         type = buffer_get_char(&incoming_packet);
1056         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1057                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1058         return type;
1059 }
1060
1061 static int
1062 packet_read_poll2(u_int32_t *seqnr_p)
1063 {
1064         static u_int packet_length = 0;
1065         u_int padlen, need;
1066         u_char *macbuf, *cp, type;
1067         u_int maclen, block_size;
1068         Enc *enc   = NULL;
1069         Mac *mac   = NULL;
1070         Comp *comp = NULL;
1071
1072         if (newkeys[MODE_IN] != NULL) {
1073                 enc  = &newkeys[MODE_IN]->enc;
1074                 mac  = &newkeys[MODE_IN]->mac;
1075                 comp = &newkeys[MODE_IN]->comp;
1076         }
1077         maclen = mac && mac->enabled ? mac->mac_len : 0;
1078         block_size = enc ? enc->block_size : 8;
1079
1080         if (packet_length == 0) {
1081                 /*
1082                  * check if input size is less than the cipher block size,
1083                  * decrypt first block and extract length of incoming packet
1084                  */
1085                 if (buffer_len(&input) < block_size)
1086                         return SSH_MSG_NONE;
1087                 buffer_clear(&incoming_packet);
1088                 cp = buffer_append_space(&incoming_packet, block_size);
1089                 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1090                     block_size);
1091                 cp = buffer_ptr(&incoming_packet);
1092                 packet_length = get_u32(cp);
1093                 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1094 #ifdef PACKET_DEBUG
1095                         buffer_dump(&incoming_packet);
1096 #endif
1097                         packet_disconnect("Bad packet length %u.", packet_length);
1098                 }
1099                 DBG(debug("input: packet len %u", packet_length+4));
1100                 buffer_consume(&input, block_size);
1101         }
1102         /* we have a partial packet of block_size bytes */
1103         need = 4 + packet_length - block_size;
1104         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1105             need, maclen));
1106         if (need % block_size != 0)
1107                 fatal("padding error: need %d block %d mod %d",
1108                     need, block_size, need % block_size);
1109         /*
1110          * check if the entire packet has been received and
1111          * decrypt into incoming_packet
1112          */
1113         if (buffer_len(&input) < need + maclen)
1114                 return SSH_MSG_NONE;
1115 #ifdef PACKET_DEBUG
1116         fprintf(stderr, "read_poll enc/full: ");
1117         buffer_dump(&input);
1118 #endif
1119         cp = buffer_append_space(&incoming_packet, need);
1120         cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1121         buffer_consume(&input, need);
1122         /*
1123          * compute MAC over seqnr and packet,
1124          * increment sequence number for incoming packet
1125          */
1126         if (mac && mac->enabled) {
1127                 macbuf = mac_compute(mac, p_read.seqnr,
1128                     buffer_ptr(&incoming_packet),
1129                     buffer_len(&incoming_packet));
1130                 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1131                         packet_disconnect("Corrupted MAC on input.");
1132                 DBG(debug("MAC #%d ok", p_read.seqnr));
1133                 buffer_consume(&input, mac->mac_len);
1134         }
1135         if (seqnr_p != NULL)
1136                 *seqnr_p = p_read.seqnr;
1137         if (++p_read.seqnr == 0)
1138                 logit("incoming seqnr wraps around");
1139         if (++p_read.packets == 0)
1140                 if (!(datafellows & SSH_BUG_NOREKEY))
1141                         fatal("XXX too many packets with same key");
1142         p_read.blocks += (packet_length + 4) / block_size;
1143
1144         /* get padlen */
1145         cp = buffer_ptr(&incoming_packet);
1146         padlen = cp[4];
1147         DBG(debug("input: padlen %d", padlen));
1148         if (padlen < 4)
1149                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1150
1151         /* skip packet size + padlen, discard padding */
1152         buffer_consume(&incoming_packet, 4 + 1);
1153         buffer_consume_end(&incoming_packet, padlen);
1154
1155         DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1156         if (comp && comp->enabled) {
1157                 buffer_clear(&compression_buffer);
1158                 buffer_uncompress(&incoming_packet, &compression_buffer);
1159                 buffer_clear(&incoming_packet);
1160                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1161                     buffer_len(&compression_buffer));
1162                 DBG(debug("input: len after de-compress %d",
1163                     buffer_len(&incoming_packet)));
1164         }
1165         /*
1166          * get packet type, implies consume.
1167          * return length of payload (without type field)
1168          */
1169         type = buffer_get_char(&incoming_packet);
1170         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1171                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1172         if (type == SSH2_MSG_NEWKEYS)
1173                 set_newkeys(MODE_IN);
1174         else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1175                 packet_enable_delayed_compress();
1176 #ifdef PACKET_DEBUG
1177         fprintf(stderr, "read/plain[%d]:\r\n", type);
1178         buffer_dump(&incoming_packet);
1179 #endif
1180         /* reset for next packet */
1181         packet_length = 0;
1182         return type;
1183 }
1184
1185 int
1186 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1187 {
1188         u_int reason, seqnr;
1189         u_char type;
1190         char *msg;
1191
1192         for (;;) {
1193                 if (compat20) {
1194                         type = packet_read_poll2(seqnr_p);
1195                         if (type)
1196                                 DBG(debug("received packet type %d", type));
1197                         switch (type) {
1198                         case SSH2_MSG_IGNORE:
1199                                 break;
1200                         case SSH2_MSG_DEBUG:
1201                                 packet_get_char();
1202                                 msg = packet_get_string(NULL);
1203                                 debug("Remote: %.900s", msg);
1204                                 xfree(msg);
1205                                 msg = packet_get_string(NULL);
1206                                 xfree(msg);
1207                                 break;
1208                         case SSH2_MSG_DISCONNECT:
1209                                 reason = packet_get_int();
1210                                 msg = packet_get_string(NULL);
1211                                 logit("Received disconnect from %s: %u: %.400s",
1212                                     get_remote_ipaddr(), reason, msg);
1213                                 xfree(msg);
1214                                 cleanup_exit(255);
1215                                 break;
1216                         case SSH2_MSG_UNIMPLEMENTED:
1217                                 seqnr = packet_get_int();
1218                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1219                                     seqnr);
1220                                 break;
1221                         default:
1222                                 return type;
1223                         }
1224                 } else {
1225                         type = packet_read_poll1();
1226                         switch (type) {
1227                         case SSH_MSG_IGNORE:
1228                                 break;
1229                         case SSH_MSG_DEBUG:
1230                                 msg = packet_get_string(NULL);
1231                                 debug("Remote: %.900s", msg);
1232                                 xfree(msg);
1233                                 break;
1234                         case SSH_MSG_DISCONNECT:
1235                                 msg = packet_get_string(NULL);
1236                                 logit("Received disconnect from %s: %.400s",
1237                                     get_remote_ipaddr(), msg);
1238                                 cleanup_exit(255);
1239                                 xfree(msg);
1240                                 break;
1241                         default:
1242                                 if (type)
1243                                         DBG(debug("received packet type %d", type));
1244                                 return type;
1245                         }
1246                 }
1247         }
1248 }
1249
1250 int
1251 packet_read_poll(void)
1252 {
1253         return packet_read_poll_seqnr(NULL);
1254 }
1255
1256 /*
1257  * Buffers the given amount of input characters.  This is intended to be used
1258  * together with packet_read_poll.
1259  */
1260
1261 void
1262 packet_process_incoming(const char *buf, u_int len)
1263 {
1264         buffer_append(&input, buf, len);
1265 }
1266
1267 /* Returns a character from the packet. */
1268
1269 u_int
1270 packet_get_char(void)
1271 {
1272         char ch;
1273
1274         buffer_get(&incoming_packet, &ch, 1);
1275         return (u_char) ch;
1276 }
1277
1278 /* Returns an integer from the packet data. */
1279
1280 u_int
1281 packet_get_int(void)
1282 {
1283         return buffer_get_int(&incoming_packet);
1284 }
1285
1286 /*
1287  * Returns an arbitrary precision integer from the packet data.  The integer
1288  * must have been initialized before this call.
1289  */
1290
1291 void
1292 packet_get_bignum(BIGNUM * value)
1293 {
1294         buffer_get_bignum(&incoming_packet, value);
1295 }
1296
1297 void
1298 packet_get_bignum2(BIGNUM * value)
1299 {
1300         buffer_get_bignum2(&incoming_packet, value);
1301 }
1302
1303 void *
1304 packet_get_raw(u_int *length_ptr)
1305 {
1306         u_int bytes = buffer_len(&incoming_packet);
1307
1308         if (length_ptr != NULL)
1309                 *length_ptr = bytes;
1310         return buffer_ptr(&incoming_packet);
1311 }
1312
1313 int
1314 packet_remaining(void)
1315 {
1316         return buffer_len(&incoming_packet);
1317 }
1318
1319 /*
1320  * Returns a string from the packet data.  The string is allocated using
1321  * xmalloc; it is the responsibility of the calling program to free it when
1322  * no longer needed.  The length_ptr argument may be NULL, or point to an
1323  * integer into which the length of the string is stored.
1324  */
1325
1326 void *
1327 packet_get_string(u_int *length_ptr)
1328 {
1329         return buffer_get_string(&incoming_packet, length_ptr);
1330 }
1331
1332 /*
1333  * Sends a diagnostic message from the server to the client.  This message
1334  * can be sent at any time (but not while constructing another message). The
1335  * message is printed immediately, but only if the client is being executed
1336  * in verbose mode.  These messages are primarily intended to ease debugging
1337  * authentication problems.   The length of the formatted message must not
1338  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1339  */
1340
1341 void
1342 packet_send_debug(const char *fmt,...)
1343 {
1344         char buf[1024];
1345         va_list args;
1346
1347         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1348                 return;
1349
1350         va_start(args, fmt);
1351         vsnprintf(buf, sizeof(buf), fmt, args);
1352         va_end(args);
1353
1354         if (compat20) {
1355                 packet_start(SSH2_MSG_DEBUG);
1356                 packet_put_char(0);     /* bool: always display */
1357                 packet_put_cstring(buf);
1358                 packet_put_cstring("");
1359         } else {
1360                 packet_start(SSH_MSG_DEBUG);
1361                 packet_put_cstring(buf);
1362         }
1363         packet_send();
1364         packet_write_wait();
1365 }
1366
1367 /*
1368  * Logs the error plus constructs and sends a disconnect packet, closes the
1369  * connection, and exits.  This function never returns. The error message
1370  * should not contain a newline.  The length of the formatted message must
1371  * not exceed 1024 bytes.
1372  */
1373
1374 void
1375 packet_disconnect(const char *fmt,...)
1376 {
1377         char buf[1024];
1378         va_list args;
1379         static int disconnecting = 0;
1380
1381         if (disconnecting)      /* Guard against recursive invocations. */
1382                 fatal("packet_disconnect called recursively.");
1383         disconnecting = 1;
1384
1385         /*
1386          * Format the message.  Note that the caller must make sure the
1387          * message is of limited size.
1388          */
1389         va_start(args, fmt);
1390         vsnprintf(buf, sizeof(buf), fmt, args);
1391         va_end(args);
1392
1393         /* Display the error locally */
1394         logit("Disconnecting: %.100s", buf);
1395
1396         /* Send the disconnect message to the other side, and wait for it to get sent. */
1397         if (compat20) {
1398                 packet_start(SSH2_MSG_DISCONNECT);
1399                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1400                 packet_put_cstring(buf);
1401                 packet_put_cstring("");
1402         } else {
1403                 packet_start(SSH_MSG_DISCONNECT);
1404                 packet_put_cstring(buf);
1405         }
1406         packet_send();
1407         packet_write_wait();
1408
1409         /* Stop listening for connections. */
1410         channel_close_all();
1411
1412         /* Close the connection. */
1413         packet_close();
1414         cleanup_exit(255);
1415 }
1416
1417 /* Checks if there is any buffered output, and tries to write some of the output. */
1418
1419 void
1420 packet_write_poll(void)
1421 {
1422         int len = buffer_len(&output);
1423
1424         if (len > 0) {
1425                 len = write(connection_out, buffer_ptr(&output), len);
1426                 if (len <= 0) {
1427                         if (errno == EAGAIN)
1428                                 return;
1429                         else
1430                                 fatal("Write failed: %.100s", strerror(errno));
1431                 }
1432                 buffer_consume(&output, len);
1433         }
1434 }
1435
1436 /*
1437  * Calls packet_write_poll repeatedly until all pending output data has been
1438  * written.
1439  */
1440
1441 void
1442 packet_write_wait(void)
1443 {
1444         fd_set *setp;
1445
1446         setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1447             sizeof(fd_mask));
1448         packet_write_poll();
1449         while (packet_have_data_to_write()) {
1450                 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1451                     sizeof(fd_mask));
1452                 FD_SET(connection_out, setp);
1453                 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1454                     (errno == EAGAIN || errno == EINTR))
1455                         ;
1456                 packet_write_poll();
1457         }
1458         xfree(setp);
1459 }
1460
1461 /* Returns true if there is buffered data to write to the connection. */
1462
1463 int
1464 packet_have_data_to_write(void)
1465 {
1466         return buffer_len(&output) != 0;
1467 }
1468
1469 /* Returns true if there is not too much data to write to the connection. */
1470
1471 int
1472 packet_not_very_much_data_to_write(void)
1473 {
1474         if (interactive_mode)
1475                 return buffer_len(&output) < 16384;
1476         else
1477                 return buffer_len(&output) < 128 * 1024;
1478 }
1479
1480
1481 static void
1482 packet_set_tos(int interactive)
1483 {
1484 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1485         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1486
1487         if (!packet_connection_is_on_socket() ||
1488             !packet_connection_is_ipv4())
1489                 return;
1490         if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1491             sizeof(tos)) < 0)
1492                 error("setsockopt IP_TOS %d: %.100s:",
1493                     tos, strerror(errno));
1494 #endif
1495 }
1496
1497 /* Informs that the current session is interactive.  Sets IP flags for that. */
1498
1499 void
1500 packet_set_interactive(int interactive)
1501 {
1502         static int called = 0;
1503
1504         if (called)
1505                 return;
1506         called = 1;
1507
1508         /* Record that we are in interactive mode. */
1509         interactive_mode = interactive;
1510
1511         /* Only set socket options if using a socket.  */
1512         if (!packet_connection_is_on_socket())
1513                 return;
1514         set_nodelay(connection_in);
1515         packet_set_tos(interactive);
1516 }
1517
1518 /* Returns true if the current connection is interactive. */
1519
1520 int
1521 packet_is_interactive(void)
1522 {
1523         return interactive_mode;
1524 }
1525
1526 int
1527 packet_set_maxsize(u_int s)
1528 {
1529         static int called = 0;
1530
1531         if (called) {
1532                 logit("packet_set_maxsize: called twice: old %d new %d",
1533                     max_packet_size, s);
1534                 return -1;
1535         }
1536         if (s < 4 * 1024 || s > 1024 * 1024) {
1537                 logit("packet_set_maxsize: bad size %d", s);
1538                 return -1;
1539         }
1540         called = 1;
1541         debug("packet_set_maxsize: setting to %d", s);
1542         max_packet_size = s;
1543         return s;
1544 }
1545
1546 /* roundup current message to pad bytes */
1547 void
1548 packet_add_padding(u_char pad)
1549 {
1550         extra_pad = pad;
1551 }
1552
1553 /*
1554  * 9.2.  Ignored Data Message
1555  *
1556  *   byte      SSH_MSG_IGNORE
1557  *   string    data
1558  *
1559  * All implementations MUST understand (and ignore) this message at any
1560  * time (after receiving the protocol version). No implementation is
1561  * required to send them. This message can be used as an additional
1562  * protection measure against advanced traffic analysis techniques.
1563  */
1564 void
1565 packet_send_ignore(int nbytes)
1566 {
1567         u_int32_t rnd = 0;
1568         int i;
1569
1570         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1571         packet_put_int(nbytes);
1572         for (i = 0; i < nbytes; i++) {
1573                 if (i % 4 == 0)
1574                         rnd = arc4random();
1575                 packet_put_char((u_char)rnd & 0xff);
1576                 rnd >>= 8;
1577         }
1578 }
1579
1580 #define MAX_PACKETS     (1U<<31)
1581 int
1582 packet_need_rekeying(void)
1583 {
1584         if (datafellows & SSH_BUG_NOREKEY)
1585                 return 0;
1586         return
1587             (p_send.packets > MAX_PACKETS) ||
1588             (p_read.packets > MAX_PACKETS) ||
1589             (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1590             (max_blocks_in  && (p_read.blocks > max_blocks_in));
1591 }
1592
1593 void
1594 packet_set_rekey_limit(u_int32_t bytes)
1595 {
1596         rekey_limit = bytes;
1597 }
1598
1599 void
1600 packet_set_server(void)
1601 {
1602         server_side = 1;
1603 }
1604
1605 void
1606 packet_set_authenticated(void)
1607 {
1608         after_authentication = 1;
1609 }