packet.c

   1 /* $OpenBSD: packet.c,v 1.162 2009/05/27 06:36:07 andreas 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 #define PACKET_MAX_SIZE (256 * 1024)
  88
  89 struct packet_state {
  90         u_int32_t seqnr;
  91         u_int32_t packets;
  92         u_int64_t blocks;
  93         u_int64_t bytes;
  94 };
  95
  96 struct packet {
  97         TAILQ_ENTRY(packet) next;
  98         u_char type;
  99         Buffer payload;
 100 };
 101
 102 struct session_state {
 103         /*
 104          * This variable contains the file descriptors used for
 105          * communicating with the other side.  connection_in is used for
 106          * reading; connection_out for writing.  These can be the same
 107          * descriptor, in which case it is assumed to be a socket.
 108          */
 109         int connection_in;
 110         int connection_out;
 111
 112         /* Protocol flags for the remote side. */
 113         u_int remote_protocol_flags;
 114
 115         /* Encryption context for receiving data.  Only used for decryption. */
 116         CipherContext receive_context;
 117
 118         /* Encryption context for sending data.  Only used for encryption. */
 119         CipherContext send_context;
 120
 121         /* Buffer for raw input data from the socket. */
 122         Buffer input;
 123
 124         /* Buffer for raw output data going to the socket. */
 125         Buffer output;
 126
 127         /* Buffer for the partial outgoing packet being constructed. */
 128         Buffer outgoing_packet;
 129
 130         /* Buffer for the incoming packet currently being processed. */
 131         Buffer incoming_packet;
 132
 133         /* Scratch buffer for packet compression/decompression. */
 134         Buffer compression_buffer;
 135         int compression_buffer_ready;
 136
 137         /*
 138          * Flag indicating whether packet compression/decompression is
 139          * enabled.
 140          */
 141         int packet_compression;
 142
 143         /* default maximum packet size */
 144         u_int max_packet_size;
 145
 146         /* Flag indicating whether this module has been initialized. */
 147         int initialized;
 148
 149         /* Set to true if the connection is interactive. */
 150         int interactive_mode;
 151
 152         /* Set to true if we are the server side. */
 153         int server_side;
 154
 155         /* Set to true if we are authenticated. */
 156         int after_authentication;
 157
 158         int keep_alive_timeouts;
 159
 160         /* The maximum time that we will wait to send or receive a packet */
 161         int packet_timeout_ms;
 162
 163         /* Session key information for Encryption and MAC */
 164         Newkeys *newkeys[MODE_MAX];
 165         struct packet_state p_read, p_send;
 166
 167         u_int64_t max_blocks_in, max_blocks_out;
 168         u_int32_t rekey_limit;
 169
 170         /* Session key for protocol v1 */
 171         u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 172         u_int ssh1_keylen;
 173
 174         /* roundup current message to extra_pad bytes */
 175         u_char extra_pad;
 176
 177         /* XXX discard incoming data after MAC error */
 178         u_int packet_discard;
 179         Mac *packet_discard_mac;
 180
 181         /* Used in packet_read_poll2() */
 182         u_int packlen;
 183
 184         TAILQ_HEAD(, packet) outgoing;
 185 };
 186
 187 static struct session_state *active_state;
 188
 189 static struct session_state *
 190 alloc_session_state()
 191 {
 192     struct session_state *s = xcalloc(1, sizeof(*s));
 193
 194     s->connection_in = -1;
 195     s->connection_out = -1;
 196     s->max_packet_size = 32768;
 197     s->packet_timeout_ms = -1;
 198     return s;
 199 }
 200
 201 /*
 202  * Sets the descriptors used for communication.  Disables encryption until
 203  * packet_set_encryption_key is called.
 204  */
 205 void
 206 packet_set_connection(int fd_in, int fd_out)
 207 {
 208         Cipher *none = cipher_by_name("none");
 209
 210         if (none == NULL)
 211                 fatal("packet_set_connection: cannot load cipher 'none'");
 212         if (active_state == NULL)
 213                 active_state = alloc_session_state();
 214         active_state->connection_in = fd_in;
 215         active_state->connection_out = fd_out;
 216         cipher_init(&active_state->send_context, none, (const u_char *)"",
 217             0, NULL, 0, CIPHER_ENCRYPT);
 218         cipher_init(&active_state->receive_context, none, (const u_char *)"",
 219             0, NULL, 0, CIPHER_DECRYPT);
 220         active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
 221         if (!active_state->initialized) {
 222                 active_state->initialized = 1;
 223                 buffer_init(&active_state->input);
 224                 buffer_init(&active_state->output);
 225                 buffer_init(&active_state->outgoing_packet);
 226                 buffer_init(&active_state->incoming_packet);
 227                 TAILQ_INIT(&active_state->outgoing);
 228                 active_state->p_send.packets = active_state->p_read.packets = 0;
 229         }
 230 }
 231
 232 void
 233 packet_set_timeout(int timeout, int count)
 234 {
 235         if (timeout == 0 || count == 0) {
 236                 active_state->packet_timeout_ms = -1;
 237                 return;
 238         }
 239         if ((INT_MAX / 1000) / count < timeout)
 240                 active_state->packet_timeout_ms = INT_MAX;
 241         else
 242                 active_state->packet_timeout_ms = timeout * count * 1000;
 243 }
 244
 245 static void
 246 packet_stop_discard(void)
 247 {
 248         if (active_state->packet_discard_mac) {
 249                 char buf[1024];
 250
 251                 memset(buf, 'a', sizeof(buf));
 252                 while (buffer_len(&active_state->incoming_packet) <
 253                     PACKET_MAX_SIZE)
 254                         buffer_append(&active_state->incoming_packet, buf,
 255                             sizeof(buf));
 256                 (void) mac_compute(active_state->packet_discard_mac,
 257                     active_state->p_read.seqnr,
 258                     buffer_ptr(&active_state->incoming_packet),
 259                     PACKET_MAX_SIZE);
 260         }
 261         logit("Finished discarding for %.200s", get_remote_ipaddr());
 262         cleanup_exit(255);
 263 }
 264
 265 static void
 266 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
 267 {
 268         if (enc == NULL || !cipher_is_cbc(enc->cipher))
 269                 packet_disconnect("Packet corrupt");
 270         if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
 271                 active_state->packet_discard_mac = mac;
 272         if (buffer_len(&active_state->input) >= discard)
 273                 packet_stop_discard();
 274         active_state->packet_discard = discard -
 275             buffer_len(&active_state->input);
 276 }
 277
 278 /* Returns 1 if remote host is connected via socket, 0 if not. */
 279
 280 int
 281 packet_connection_is_on_socket(void)
 282 {
 283         struct sockaddr_storage from, to;
 284         socklen_t fromlen, tolen;
 285
 286         /* filedescriptors in and out are the same, so it's a socket */
 287         if (active_state->connection_in == active_state->connection_out)
 288                 return 1;
 289         fromlen = sizeof(from);
 290         memset(&from, 0, sizeof(from));
 291         if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
 292             &fromlen) < 0)
 293                 return 0;
 294         tolen = sizeof(to);
 295         memset(&to, 0, sizeof(to));
 296         if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
 297             &tolen) < 0)
 298                 return 0;
 299         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 300                 return 0;
 301         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 302                 return 0;
 303         return 1;
 304 }
 305
 306 /*
 307  * Exports an IV from the CipherContext required to export the key
 308  * state back from the unprivileged child to the privileged parent
 309  * process.
 310  */
 311
 312 void
 313 packet_get_keyiv(int mode, u_char *iv, u_int len)
 314 {
 315         CipherContext *cc;
 316
 317         if (mode == MODE_OUT)
 318                 cc = &active_state->send_context;
 319         else
 320                 cc = &active_state->receive_context;
 321
 322         cipher_get_keyiv(cc, iv, len);
 323 }
 324
 325 int
 326 packet_get_keycontext(int mode, u_char *dat)
 327 {
 328         CipherContext *cc;
 329
 330         if (mode == MODE_OUT)
 331                 cc = &active_state->send_context;
 332         else
 333                 cc = &active_state->receive_context;
 334
 335         return (cipher_get_keycontext(cc, dat));
 336 }
 337
 338 void
 339 packet_set_keycontext(int mode, u_char *dat)
 340 {
 341         CipherContext *cc;
 342
 343         if (mode == MODE_OUT)
 344                 cc = &active_state->send_context;
 345         else
 346                 cc = &active_state->receive_context;
 347
 348         cipher_set_keycontext(cc, dat);
 349 }
 350
 351 int
 352 packet_get_keyiv_len(int mode)
 353 {
 354         CipherContext *cc;
 355
 356         if (mode == MODE_OUT)
 357                 cc = &active_state->send_context;
 358         else
 359                 cc = &active_state->receive_context;
 360
 361         return (cipher_get_keyiv_len(cc));
 362 }
 363
 364 void
 365 packet_set_iv(int mode, u_char *dat)
 366 {
 367         CipherContext *cc;
 368
 369         if (mode == MODE_OUT)
 370                 cc = &active_state->send_context;
 371         else
 372                 cc = &active_state->receive_context;
 373
 374         cipher_set_keyiv(cc, dat);
 375 }
 376
 377 int
 378 packet_get_ssh1_cipher(void)
 379 {
 380         return (cipher_get_number(active_state->receive_context.cipher));
 381 }
 382
 383 void
 384 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets,
 385     u_int64_t *bytes)
 386 {
 387         struct packet_state *state;
 388
 389         state = (mode == MODE_IN) ?
 390             &active_state->p_read : &active_state->p_send;
 391         if (seqnr)
 392                 *seqnr = state->seqnr;
 393         if (blocks)
 394                 *blocks = state->blocks;
 395         if (packets)
 396                 *packets = state->packets;
 397         if (bytes)
 398                 *bytes = state->bytes;
 399 }
 400
 401 void
 402 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
 403     u_int64_t bytes)
 404 {
 405         struct packet_state *state;
 406
 407         state = (mode == MODE_IN) ?
 408             &active_state->p_read : &active_state->p_send;
 409         state->seqnr = seqnr;
 410         state->blocks = blocks;
 411         state->packets = packets;
 412         state->bytes = bytes;
 413 }
 414
 415 /* returns 1 if connection is via ipv4 */
 416
 417 int
 418 packet_connection_is_ipv4(void)
 419 {
 420         struct sockaddr_storage to;
 421         socklen_t tolen = sizeof(to);
 422
 423         memset(&to, 0, sizeof(to));
 424         if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
 425             &tolen) < 0)
 426                 return 0;
 427         if (to.ss_family == AF_INET)
 428                 return 1;
 429 #ifdef IPV4_IN_IPV6
 430         if (to.ss_family == AF_INET6 &&
 431             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 432                 return 1;
 433 #endif
 434         return 0;
 435 }
 436
 437 /* Sets the connection into non-blocking mode. */
 438
 439 void
 440 packet_set_nonblocking(void)
 441 {
 442         /* Set the socket into non-blocking mode. */
 443         set_nonblock(active_state->connection_in);
 444
 445         if (active_state->connection_out != active_state->connection_in)
 446                 set_nonblock(active_state->connection_out);
 447 }
 448
 449 /* Returns the socket used for reading. */
 450
 451 int
 452 packet_get_connection_in(void)
 453 {
 454         return active_state->connection_in;
 455 }
 456
 457 /* Returns the descriptor used for writing. */
 458
 459 int
 460 packet_get_connection_out(void)
 461 {
 462         return active_state->connection_out;
 463 }
 464
 465 /* Closes the connection and clears and frees internal data structures. */
 466
 467 void
 468 packet_close(void)
 469 {
 470         if (!active_state->initialized)
 471                 return;
 472         active_state->initialized = 0;
 473         if (active_state->connection_in == active_state->connection_out) {
 474                 shutdown(active_state->connection_out, SHUT_RDWR);
 475                 close(active_state->connection_out);
 476         } else {
 477                 close(active_state->connection_in);
 478                 close(active_state->connection_out);
 479         }
 480         buffer_free(&active_state->input);
 481         buffer_free(&active_state->output);
 482         buffer_free(&active_state->outgoing_packet);
 483         buffer_free(&active_state->incoming_packet);
 484         if (active_state->compression_buffer_ready) {
 485                 buffer_free(&active_state->compression_buffer);
 486                 buffer_compress_uninit();
 487         }
 488         cipher_cleanup(&active_state->send_context);
 489         cipher_cleanup(&active_state->receive_context);
 490 }
 491
 492 /* Sets remote side protocol flags. */
 493
 494 void
 495 packet_set_protocol_flags(u_int protocol_flags)
 496 {
 497         active_state->remote_protocol_flags = protocol_flags;
 498 }
 499
 500 /* Returns the remote protocol flags set earlier by the above function. */
 501
 502 u_int
 503 packet_get_protocol_flags(void)
 504 {
 505         return active_state->remote_protocol_flags;
 506 }
 507
 508 /*
 509  * Starts packet compression from the next packet on in both directions.
 510  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 511  */
 512
 513 static void
 514 packet_init_compression(void)
 515 {
 516         if (active_state->compression_buffer_ready == 1)
 517                 return;
 518         active_state->compression_buffer_ready = 1;
 519         buffer_init(&active_state->compression_buffer);
 520 }
 521
 522 void
 523 packet_start_compression(int level)
 524 {
 525         if (active_state->packet_compression && !compat20)
 526                 fatal("Compression already enabled.");
 527         active_state->packet_compression = 1;
 528         packet_init_compression();
 529         buffer_compress_init_send(level);
 530         buffer_compress_init_recv();
 531 }
 532
 533 /*
 534  * Causes any further packets to be encrypted using the given key.  The same
 535  * key is used for both sending and reception.  However, both directions are
 536  * encrypted independently of each other.
 537  */
 538
 539 void
 540 packet_set_encryption_key(const u_char *key, u_int keylen,
 541     int number)
 542 {
 543         Cipher *cipher = cipher_by_number(number);
 544
 545         if (cipher == NULL)
 546                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 547         if (keylen < 20)
 548                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 549         if (keylen > SSH_SESSION_KEY_LENGTH)
 550                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 551         memcpy(active_state->ssh1_key, key, keylen);
 552         active_state->ssh1_keylen = keylen;
 553         cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
 554             0, CIPHER_ENCRYPT);
 555         cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
 556             0, CIPHER_DECRYPT);
 557 }
 558
 559 u_int
 560 packet_get_encryption_key(u_char *key)
 561 {
 562         if (key == NULL)
 563                 return (active_state->ssh1_keylen);
 564         memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
 565         return (active_state->ssh1_keylen);
 566 }
 567
 568 /* Start constructing a packet to send. */
 569 void
 570 packet_start(u_char type)
 571 {
 572         u_char buf[9];
 573         int len;
 574
 575         DBG(debug("packet_start[%d]", type));
 576         len = compat20 ? 6 : 9;
 577         memset(buf, 0, len - 1);
 578         buf[len - 1] = type;
 579         buffer_clear(&active_state->outgoing_packet);
 580         buffer_append(&active_state->outgoing_packet, buf, len);
 581 }
 582
 583 /* Append payload. */
 584 void
 585 packet_put_char(int value)
 586 {
 587         char ch = value;
 588
 589         buffer_append(&active_state->outgoing_packet, &ch, 1);
 590 }
 591
 592 void
 593 packet_put_int(u_int value)
 594 {
 595         buffer_put_int(&active_state->outgoing_packet, value);
 596 }
 597
 598 void
 599 packet_put_int64(u_int64_t value)
 600 {
 601         buffer_put_int64(&active_state->outgoing_packet, value);
 602 }
 603
 604 void
 605 packet_put_string(const void *buf, u_int len)
 606 {
 607         buffer_put_string(&active_state->outgoing_packet, buf, len);
 608 }
 609
 610 void
 611 packet_put_cstring(const char *str)
 612 {
 613         buffer_put_cstring(&active_state->outgoing_packet, str);
 614 }
 615
 616 void
 617 packet_put_raw(const void *buf, u_int len)
 618 {
 619         buffer_append(&active_state->outgoing_packet, buf, len);
 620 }
 621
 622 void
 623 packet_put_bignum(BIGNUM * value)
 624 {
 625         buffer_put_bignum(&active_state->outgoing_packet, value);
 626 }
 627
 628 void
 629 packet_put_bignum2(BIGNUM * value)
 630 {
 631         buffer_put_bignum2(&active_state->outgoing_packet, value);
 632 }
 633
 634 /*
 635  * Finalizes and sends the packet.  If the encryption key has been set,
 636  * encrypts the packet before sending.
 637  */
 638
 639 static void
 640 packet_send1(void)
 641 {
 642         u_char buf[8], *cp;
 643         int i, padding, len;
 644         u_int checksum;
 645         u_int32_t rnd = 0;
 646
 647         /*
 648          * If using packet compression, compress the payload of the outgoing
 649          * packet.
 650          */
 651         if (active_state->packet_compression) {
 652                 buffer_clear(&active_state->compression_buffer);
 653                 /* Skip padding. */
 654                 buffer_consume(&active_state->outgoing_packet, 8);
 655                 /* padding */
 656                 buffer_append(&active_state->compression_buffer,
 657                     "\0\0\0\0\0\0\0\0", 8);
 658                 buffer_compress(&active_state->outgoing_packet,
 659                     &active_state->compression_buffer);
 660                 buffer_clear(&active_state->outgoing_packet);
 661                 buffer_append(&active_state->outgoing_packet,
 662                     buffer_ptr(&active_state->compression_buffer),
 663                     buffer_len(&active_state->compression_buffer));
 664         }
 665         /* Compute packet length without padding (add checksum, remove padding). */
 666         len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
 667
 668         /* Insert padding. Initialized to zero in packet_start1() */
 669         padding = 8 - len % 8;
 670         if (!active_state->send_context.plaintext) {
 671                 cp = buffer_ptr(&active_state->outgoing_packet);
 672                 for (i = 0; i < padding; i++) {
 673                         if (i % 4 == 0)
 674                                 rnd = arc4random();
 675                         cp[7 - i] = rnd & 0xff;
 676                         rnd >>= 8;
 677                 }
 678         }
 679         buffer_consume(&active_state->outgoing_packet, 8 - padding);
 680
 681         /* Add check bytes. */
 682         checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
 683             buffer_len(&active_state->outgoing_packet));
 684         put_u32(buf, checksum);
 685         buffer_append(&active_state->outgoing_packet, buf, 4);
 686
 687 #ifdef PACKET_DEBUG
 688         fprintf(stderr, "packet_send plain: ");
 689         buffer_dump(&active_state->outgoing_packet);
 690 #endif
 691
 692         /* Append to output. */
 693         put_u32(buf, len);
 694         buffer_append(&active_state->output, buf, 4);
 695         cp = buffer_append_space(&active_state->output,
 696             buffer_len(&active_state->outgoing_packet));
 697         cipher_crypt(&active_state->send_context, cp,
 698             buffer_ptr(&active_state->outgoing_packet),
 699             buffer_len(&active_state->outgoing_packet));
 700
 701 #ifdef PACKET_DEBUG
 702         fprintf(stderr, "encrypted: ");
 703         buffer_dump(&active_state->output);
 704 #endif
 705         active_state->p_send.packets++;
 706         active_state->p_send.bytes += len +
 707             buffer_len(&active_state->outgoing_packet);
 708         buffer_clear(&active_state->outgoing_packet);
 709
 710         /*
 711          * Note that the packet is now only buffered in output.  It won't be
 712          * actually sent until packet_write_wait or packet_write_poll is
 713          * called.
 714          */
 715 }
 716
 717 void
 718 set_newkeys(int mode)
 719 {
 720         Enc *enc;
 721         Mac *mac;
 722         Comp *comp;
 723         CipherContext *cc;
 724         u_int64_t *max_blocks;
 725         int crypt_type;
 726
 727         debug2("set_newkeys: mode %d", mode);
 728
 729         if (mode == MODE_OUT) {
 730                 cc = &active_state->send_context;
 731                 crypt_type = CIPHER_ENCRYPT;
 732                 active_state->p_send.packets = active_state->p_send.blocks = 0;
 733                 max_blocks = &active_state->max_blocks_out;
 734         } else {
 735                 cc = &active_state->receive_context;
 736                 crypt_type = CIPHER_DECRYPT;
 737                 active_state->p_read.packets = active_state->p_read.blocks = 0;
 738                 max_blocks = &active_state->max_blocks_in;
 739         }
 740         if (active_state->newkeys[mode] != NULL) {
 741                 debug("set_newkeys: rekeying");
 742                 cipher_cleanup(cc);
 743                 enc  = &active_state->newkeys[mode]->enc;
 744                 mac  = &active_state->newkeys[mode]->mac;
 745                 comp = &active_state->newkeys[mode]->comp;
 746                 mac_clear(mac);
 747                 xfree(enc->name);
 748                 xfree(enc->iv);
 749                 xfree(enc->key);
 750                 xfree(mac->name);
 751                 xfree(mac->key);
 752                 xfree(comp->name);
 753                 xfree(active_state->newkeys[mode]);
 754         }
 755         active_state->newkeys[mode] = kex_get_newkeys(mode);
 756         if (active_state->newkeys[mode] == NULL)
 757                 fatal("newkeys: no keys for mode %d", mode);
 758         enc  = &active_state->newkeys[mode]->enc;
 759         mac  = &active_state->newkeys[mode]->mac;
 760         comp = &active_state->newkeys[mode]->comp;
 761         if (mac_init(mac) == 0)
 762                 mac->enabled = 1;
 763         DBG(debug("cipher_init_context: %d", mode));
 764         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 765             enc->iv, enc->block_size, crypt_type);
 766         /* Deleting the keys does not gain extra security */
 767         /* memset(enc->iv,  0, enc->block_size);
 768            memset(enc->key, 0, enc->key_len);
 769            memset(mac->key, 0, mac->key_len); */
 770         if ((comp->type == COMP_ZLIB ||
 771             (comp->type == COMP_DELAYED &&
 772              active_state->after_authentication)) && comp->enabled == 0) {
 773                 packet_init_compression();
 774                 if (mode == MODE_OUT)
 775                         buffer_compress_init_send(6);
 776                 else
 777                         buffer_compress_init_recv();
 778                 comp->enabled = 1;
 779         }
 780         /*
 781          * The 2^(blocksize*2) limit is too expensive for 3DES,
 782          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 783          */
 784         if (enc->block_size >= 16)
 785                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 786         else
 787                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 788         if (active_state->rekey_limit)
 789                 *max_blocks = MIN(*max_blocks,
 790                     active_state->rekey_limit / enc->block_size);
 791 }
 792
 793 /*
 794  * Delayed compression for SSH2 is enabled after authentication:
 795  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 796  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 797  */
 798 static void
 799 packet_enable_delayed_compress(void)
 800 {
 801         Comp *comp = NULL;
 802         int mode;
 803
 804         /*
 805          * Remember that we are past the authentication step, so rekeying
 806          * with COMP_DELAYED will turn on compression immediately.
 807          */
 808         active_state->after_authentication = 1;
 809         for (mode = 0; mode < MODE_MAX; mode++) {
 810                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 811                 if (active_state->newkeys[mode] == NULL)
 812                         continue;
 813                 comp = &active_state->newkeys[mode]->comp;
 814                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 815                         packet_init_compression();
 816                         if (mode == MODE_OUT)
 817                                 buffer_compress_init_send(6);
 818                         else
 819                                 buffer_compress_init_recv();
 820                         comp->enabled = 1;
 821                 }
 822         }
 823 }
 824
 825 /*
 826  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 827  */
 828 static void
 829 packet_send2_wrapped(void)
 830 {
 831         u_char type, *cp, *macbuf = NULL;
 832         u_char padlen, pad;
 833         u_int packet_length = 0;
 834         u_int i, len;
 835         u_int32_t rnd = 0;
 836         Enc *enc   = NULL;
 837         Mac *mac   = NULL;
 838         Comp *comp = NULL;
 839         int block_size;
 840
 841         if (active_state->newkeys[MODE_OUT] != NULL) {
 842                 enc  = &active_state->newkeys[MODE_OUT]->enc;
 843                 mac  = &active_state->newkeys[MODE_OUT]->mac;
 844                 comp = &active_state->newkeys[MODE_OUT]->comp;
 845         }
 846         block_size = enc ? enc->block_size : 8;
 847
 848         cp = buffer_ptr(&active_state->outgoing_packet);
 849         type = cp[5];
 850
 851 #ifdef PACKET_DEBUG
 852         fprintf(stderr, "plain:     ");
 853         buffer_dump(&active_state->outgoing_packet);
 854 #endif
 855
 856         if (comp && comp->enabled) {
 857                 len = buffer_len(&active_state->outgoing_packet);
 858                 /* skip header, compress only payload */
 859                 buffer_consume(&active_state->outgoing_packet, 5);
 860                 buffer_clear(&active_state->compression_buffer);
 861                 buffer_compress(&active_state->outgoing_packet,
 862                     &active_state->compression_buffer);
 863                 buffer_clear(&active_state->outgoing_packet);
 864                 buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
 865                 buffer_append(&active_state->outgoing_packet,
 866                     buffer_ptr(&active_state->compression_buffer),
 867                     buffer_len(&active_state->compression_buffer));
 868                 DBG(debug("compression: raw %d compressed %d", len,
 869                     buffer_len(&active_state->outgoing_packet)));
 870         }
 871
 872         /* sizeof (packet_len + pad_len + payload) */
 873         len = buffer_len(&active_state->outgoing_packet);
 874
 875         /*
 876          * calc size of padding, alloc space, get random data,
 877          * minimum padding is 4 bytes
 878          */
 879         padlen = block_size - (len % block_size);
 880         if (padlen < 4)
 881                 padlen += block_size;
 882         if (active_state->extra_pad) {
 883                 /* will wrap if extra_pad+padlen > 255 */
 884                 active_state->extra_pad =
 885                     roundup(active_state->extra_pad, block_size);
 886                 pad = active_state->extra_pad -
 887                     ((len + padlen) % active_state->extra_pad);
 888                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 889                     pad, len, padlen, active_state->extra_pad);
 890                 padlen += pad;
 891                 active_state->extra_pad = 0;
 892         }
 893         cp = buffer_append_space(&active_state->outgoing_packet, padlen);
 894         if (enc && !active_state->send_context.plaintext) {
 895                 /* random padding */
 896                 for (i = 0; i < padlen; i++) {
 897                         if (i % 4 == 0)
 898                                 rnd = arc4random();
 899                         cp[i] = rnd & 0xff;
 900                         rnd >>= 8;
 901                 }
 902         } else {
 903                 /* clear padding */
 904                 memset(cp, 0, padlen);
 905         }
 906         /* packet_length includes payload, padding and padding length field */
 907         packet_length = buffer_len(&active_state->outgoing_packet) - 4;
 908         cp = buffer_ptr(&active_state->outgoing_packet);
 909         put_u32(cp, packet_length);
 910         cp[4] = padlen;
 911         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 912
 913         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 914         if (mac && mac->enabled) {
 915                 macbuf = mac_compute(mac, active_state->p_send.seqnr,
 916                     buffer_ptr(&active_state->outgoing_packet),
 917                     buffer_len(&active_state->outgoing_packet));
 918                 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
 919         }
 920         /* encrypt packet and append to output buffer. */
 921         cp = buffer_append_space(&active_state->output,
 922             buffer_len(&active_state->outgoing_packet));
 923         cipher_crypt(&active_state->send_context, cp,
 924             buffer_ptr(&active_state->outgoing_packet),
 925             buffer_len(&active_state->outgoing_packet));
 926         /* append unencrypted MAC */
 927         if (mac && mac->enabled)
 928                 buffer_append(&active_state->output, macbuf, mac->mac_len);
 929 #ifdef PACKET_DEBUG
 930         fprintf(stderr, "encrypted: ");
 931         buffer_dump(&active_state->output);
 932 #endif
 933         /* increment sequence number for outgoing packets */
 934         if (++active_state->p_send.seqnr == 0)
 935                 logit("outgoing seqnr wraps around");
 936         if (++active_state->p_send.packets == 0)
 937                 if (!(datafellows & SSH_BUG_NOREKEY))
 938                         fatal("XXX too many packets with same key");
 939         active_state->p_send.blocks += (packet_length + 4) / block_size;
 940         active_state->p_send.bytes += packet_length + 4;
 941         buffer_clear(&active_state->outgoing_packet);
 942
 943         if (type == SSH2_MSG_NEWKEYS)
 944                 set_newkeys(MODE_OUT);
 945         else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
 946                 packet_enable_delayed_compress();
 947 }
 948
 949 static void
 950 packet_send2(void)
 951 {
 952         static int rekeying = 0;
 953         struct packet *p;
 954         u_char type, *cp;
 955
 956         cp = buffer_ptr(&active_state->outgoing_packet);
 957         type = cp[5];
 958
 959         /* during rekeying we can only send key exchange messages */
 960         if (rekeying) {
 961                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 962                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 963                         debug("enqueue packet: %u", type);
 964                         p = xmalloc(sizeof(*p));
 965                         p->type = type;
 966                         memcpy(&p->payload, &active_state->outgoing_packet,
 967                             sizeof(Buffer));
 968                         buffer_init(&active_state->outgoing_packet);
 969                         TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
 970                         return;
 971                 }
 972         }
 973
 974         /* rekeying starts with sending KEXINIT */
 975         if (type == SSH2_MSG_KEXINIT)
 976                 rekeying = 1;
 977
 978         packet_send2_wrapped();
 979
 980         /* after a NEWKEYS message we can send the complete queue */
 981         if (type == SSH2_MSG_NEWKEYS) {
 982                 rekeying = 0;
 983                 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
 984                         type = p->type;
 985                         debug("dequeue packet: %u", type);
 986                         buffer_free(&active_state->outgoing_packet);
 987                         memcpy(&active_state->outgoing_packet, &p->payload,
 988                             sizeof(Buffer));
 989                         TAILQ_REMOVE(&active_state->outgoing, p, next);
 990                         xfree(p);
 991                         packet_send2_wrapped();
 992                 }
 993         }
 994 }
 995
 996 void
 997 packet_send(void)
 998 {
 999         if (compat20)
1000                 packet_send2();
1001         else
1002                 packet_send1();
1003         DBG(debug("packet_send done"));
1004 }
1005
1006 /*
1007  * Waits until a packet has been received, and returns its type.  Note that
1008  * no other data is processed until this returns, so this function should not
1009  * be used during the interactive session.
1010  */
1011
1012 int
1013 packet_read_seqnr(u_int32_t *seqnr_p)
1014 {
1015         int type, len, ret, ms_remain;
1016         fd_set *setp;
1017         char buf[8192];
1018         struct timeval timeout, start, *timeoutp = NULL;
1019
1020         DBG(debug("packet_read()"));
1021
1022         setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1023             NFDBITS), sizeof(fd_mask));
1024
1025         /* Since we are blocking, ensure that all written packets have been sent. */
1026         packet_write_wait();
1027
1028         /* Stay in the loop until we have received a complete packet. */
1029         for (;;) {
1030                 /* Try to read a packet from the buffer. */
1031                 type = packet_read_poll_seqnr(seqnr_p);
1032                 if (!compat20 && (
1033                     type == SSH_SMSG_SUCCESS
1034                     || type == SSH_SMSG_FAILURE
1035                     || type == SSH_CMSG_EOF
1036                     || type == SSH_CMSG_EXIT_CONFIRMATION))
1037                         packet_check_eom();
1038                 /* If we got a packet, return it. */
1039                 if (type != SSH_MSG_NONE) {
1040                         xfree(setp);
1041                         return type;
1042                 }
1043                 /*
1044                  * Otherwise, wait for some data to arrive, add it to the
1045                  * buffer, and try again.
1046                  */
1047                 memset(setp, 0, howmany(active_state->connection_in + 1,
1048                     NFDBITS) * sizeof(fd_mask));
1049                 FD_SET(active_state->connection_in, setp);
1050
1051                 if (active_state->packet_timeout_ms > 0) {
1052                         ms_remain = active_state->packet_timeout_ms;
1053                         timeoutp = &timeout;
1054                 }
1055                 /* Wait for some data to arrive. */
1056                 for (;;) {
1057                         if (active_state->packet_timeout_ms != -1) {
1058                                 ms_to_timeval(&timeout, ms_remain);
1059                                 gettimeofday(&start, NULL);
1060                         }
1061                         if ((ret = select(active_state->connection_in + 1, setp,
1062                             NULL, NULL, timeoutp)) >= 0)
1063                                 break;
1064                         if (errno != EAGAIN && errno != EINTR &&
1065                             errno != EWOULDBLOCK)
1066                                 break;
1067                         if (active_state->packet_timeout_ms == -1)
1068                                 continue;
1069                         ms_subtract_diff(&start, &ms_remain);
1070                         if (ms_remain <= 0) {
1071                                 ret = 0;
1072                                 break;
1073                         }
1074                 }
1075                 if (ret == 0) {
1076                         logit("Connection to %.200s timed out while "
1077                             "waiting to read", get_remote_ipaddr());
1078                         cleanup_exit(255);
1079                 }
1080                 /* Read data from the socket. */
1081                 len = read(active_state->connection_in, buf, sizeof(buf));
1082                 if (len == 0) {
1083                         logit("Connection closed by %.200s", get_remote_ipaddr());
1084                         cleanup_exit(255);
1085                 }
1086                 if (len < 0)
1087                         fatal("Read from socket failed: %.100s", strerror(errno));
1088                 /* Append it to the buffer. */
1089                 packet_process_incoming(buf, len);
1090         }
1091         /* NOTREACHED */
1092 }
1093
1094 int
1095 packet_read(void)
1096 {
1097         return packet_read_seqnr(NULL);
1098 }
1099
1100 /*
1101  * Waits until a packet has been received, verifies that its type matches
1102  * that given, and gives a fatal error and exits if there is a mismatch.
1103  */
1104
1105 void
1106 packet_read_expect(int expected_type)
1107 {
1108         int type;
1109
1110         type = packet_read();
1111         if (type != expected_type)
1112                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1113                     expected_type, type);
1114 }
1115
1116 /* Checks if a full packet is available in the data received so far via
1117  * packet_process_incoming.  If so, reads the packet; otherwise returns
1118  * SSH_MSG_NONE.  This does not wait for data from the connection.
1119  *
1120  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1121  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1122  * to higher levels.
1123  */
1124
1125 static int
1126 packet_read_poll1(void)
1127 {
1128         u_int len, padded_len;
1129         u_char *cp, type;
1130         u_int checksum, stored_checksum;
1131
1132         /* Check if input size is less than minimum packet size. */
1133         if (buffer_len(&active_state->input) < 4 + 8)
1134                 return SSH_MSG_NONE;
1135         /* Get length of incoming packet. */
1136         cp = buffer_ptr(&active_state->input);
1137         len = get_u32(cp);
1138         if (len < 1 + 2 + 2 || len > 256 * 1024)
1139                 packet_disconnect("Bad packet length %u.", len);
1140         padded_len = (len + 8) & ~7;
1141
1142         /* Check if the packet has been entirely received. */
1143         if (buffer_len(&active_state->input) < 4 + padded_len)
1144                 return SSH_MSG_NONE;
1145
1146         /* The entire packet is in buffer. */
1147
1148         /* Consume packet length. */
1149         buffer_consume(&active_state->input, 4);
1150
1151         /*
1152          * Cryptographic attack detector for ssh
1153          * (C)1998 CORE-SDI, Buenos Aires Argentina
1154          * Ariel Futoransky(futo@core-sdi.com)
1155          */
1156         if (!active_state->receive_context.plaintext) {
1157                 switch (detect_attack(buffer_ptr(&active_state->input),
1158                     padded_len)) {
1159                 case DEATTACK_DETECTED:
1160                         packet_disconnect("crc32 compensation attack: "
1161                             "network attack detected");
1162                 case DEATTACK_DOS_DETECTED:
1163                         packet_disconnect("deattack denial of "
1164                             "service detected");
1165                 }
1166         }
1167
1168         /* Decrypt data to incoming_packet. */
1169         buffer_clear(&active_state->incoming_packet);
1170         cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1171         cipher_crypt(&active_state->receive_context, cp,
1172             buffer_ptr(&active_state->input), padded_len);
1173
1174         buffer_consume(&active_state->input, padded_len);
1175
1176 #ifdef PACKET_DEBUG
1177         fprintf(stderr, "read_poll plain: ");
1178         buffer_dump(&active_state->incoming_packet);
1179 #endif
1180
1181         /* Compute packet checksum. */
1182         checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1183             buffer_len(&active_state->incoming_packet) - 4);
1184
1185         /* Skip padding. */
1186         buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1187
1188         /* Test check bytes. */
1189         if (len != buffer_len(&active_state->incoming_packet))
1190                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1191                     len, buffer_len(&active_state->incoming_packet));
1192
1193         cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1194         stored_checksum = get_u32(cp);
1195         if (checksum != stored_checksum)
1196                 packet_disconnect("Corrupted check bytes on input.");
1197         buffer_consume_end(&active_state->incoming_packet, 4);
1198
1199         if (active_state->packet_compression) {
1200                 buffer_clear(&active_state->compression_buffer);
1201                 buffer_uncompress(&active_state->incoming_packet,
1202                     &active_state->compression_buffer);
1203                 buffer_clear(&active_state->incoming_packet);
1204                 buffer_append(&active_state->incoming_packet,
1205                     buffer_ptr(&active_state->compression_buffer),
1206                     buffer_len(&active_state->compression_buffer));
1207         }
1208         active_state->p_read.packets++;
1209         active_state->p_read.bytes += padded_len + 4;
1210         type = buffer_get_char(&active_state->incoming_packet);
1211         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1212                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1213         return type;
1214 }
1215
1216 static int
1217 packet_read_poll2(u_int32_t *seqnr_p)
1218 {
1219         u_int padlen, need;
1220         u_char *macbuf, *cp, type;
1221         u_int maclen, block_size;
1222         Enc *enc   = NULL;
1223         Mac *mac   = NULL;
1224         Comp *comp = NULL;
1225
1226         if (active_state->packet_discard)
1227                 return SSH_MSG_NONE;
1228
1229         if (active_state->newkeys[MODE_IN] != NULL) {
1230                 enc  = &active_state->newkeys[MODE_IN]->enc;
1231                 mac  = &active_state->newkeys[MODE_IN]->mac;
1232                 comp = &active_state->newkeys[MODE_IN]->comp;
1233         }
1234         maclen = mac && mac->enabled ? mac->mac_len : 0;
1235         block_size = enc ? enc->block_size : 8;
1236
1237         if (active_state->packlen == 0) {
1238                 /*
1239                  * check if input size is less than the cipher block size,
1240                  * decrypt first block and extract length of incoming packet
1241                  */
1242                 if (buffer_len(&active_state->input) < block_size)
1243                         return SSH_MSG_NONE;
1244                 buffer_clear(&active_state->incoming_packet);
1245                 cp = buffer_append_space(&active_state->incoming_packet,
1246                     block_size);
1247                 cipher_crypt(&active_state->receive_context, cp,
1248                     buffer_ptr(&active_state->input), block_size);
1249                 cp = buffer_ptr(&active_state->incoming_packet);
1250                 active_state->packlen = get_u32(cp);
1251                 if (active_state->packlen < 1 + 4 ||
1252                     active_state->packlen > PACKET_MAX_SIZE) {
1253 #ifdef PACKET_DEBUG
1254                         buffer_dump(&active_state->incoming_packet);
1255 #endif
1256                         logit("Bad packet length %u.", active_state->packlen);
1257                         packet_start_discard(enc, mac, active_state->packlen,
1258                             PACKET_MAX_SIZE);
1259                         return SSH_MSG_NONE;
1260                 }
1261                 DBG(debug("input: packet len %u", active_state->packlen+4));
1262                 buffer_consume(&active_state->input, block_size);
1263         }
1264         /* we have a partial packet of block_size bytes */
1265         need = 4 + active_state->packlen - block_size;
1266         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1267             need, maclen));
1268         if (need % block_size != 0) {
1269                 logit("padding error: need %d block %d mod %d",
1270                     need, block_size, need % block_size);
1271                 packet_start_discard(enc, mac, active_state->packlen,
1272                     PACKET_MAX_SIZE - block_size);
1273                 return SSH_MSG_NONE;
1274         }
1275         /*
1276          * check if the entire packet has been received and
1277          * decrypt into incoming_packet
1278          */
1279         if (buffer_len(&active_state->input) < need + maclen)
1280                 return SSH_MSG_NONE;
1281 #ifdef PACKET_DEBUG
1282         fprintf(stderr, "read_poll enc/full: ");
1283         buffer_dump(&active_state->input);
1284 #endif
1285         cp = buffer_append_space(&active_state->incoming_packet, need);
1286         cipher_crypt(&active_state->receive_context, cp,
1287             buffer_ptr(&active_state->input), need);
1288         buffer_consume(&active_state->input, need);
1289         /*
1290          * compute MAC over seqnr and packet,
1291          * increment sequence number for incoming packet
1292          */
1293         if (mac && mac->enabled) {
1294                 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1295                     buffer_ptr(&active_state->incoming_packet),
1296                     buffer_len(&active_state->incoming_packet));
1297                 if (memcmp(macbuf, buffer_ptr(&active_state->input),
1298                     mac->mac_len) != 0) {
1299                         logit("Corrupted MAC on input.");
1300                         if (need > PACKET_MAX_SIZE)
1301                                 fatal("internal error need %d", need);
1302                         packet_start_discard(enc, mac, active_state->packlen,
1303                             PACKET_MAX_SIZE - need);
1304                         return SSH_MSG_NONE;
1305                 }
1306
1307                 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1308                 buffer_consume(&active_state->input, mac->mac_len);
1309         }
1310         /* XXX now it's safe to use fatal/packet_disconnect */
1311         if (seqnr_p != NULL)
1312                 *seqnr_p = active_state->p_read.seqnr;
1313         if (++active_state->p_read.seqnr == 0)
1314                 logit("incoming seqnr wraps around");
1315         if (++active_state->p_read.packets == 0)
1316                 if (!(datafellows & SSH_BUG_NOREKEY))
1317                         fatal("XXX too many packets with same key");
1318         active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1319         active_state->p_read.bytes += active_state->packlen + 4;
1320
1321         /* get padlen */
1322         cp = buffer_ptr(&active_state->incoming_packet);
1323         padlen = cp[4];
1324         DBG(debug("input: padlen %d", padlen));
1325         if (padlen < 4)
1326                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1327
1328         /* skip packet size + padlen, discard padding */
1329         buffer_consume(&active_state->incoming_packet, 4 + 1);
1330         buffer_consume_end(&active_state->incoming_packet, padlen);
1331
1332         DBG(debug("input: len before de-compress %d",
1333             buffer_len(&active_state->incoming_packet)));
1334         if (comp && comp->enabled) {
1335                 buffer_clear(&active_state->compression_buffer);
1336                 buffer_uncompress(&active_state->incoming_packet,
1337                     &active_state->compression_buffer);
1338                 buffer_clear(&active_state->incoming_packet);
1339                 buffer_append(&active_state->incoming_packet,
1340                     buffer_ptr(&active_state->compression_buffer),
1341                     buffer_len(&active_state->compression_buffer));
1342                 DBG(debug("input: len after de-compress %d",
1343                     buffer_len(&active_state->incoming_packet)));
1344         }
1345         /*
1346          * get packet type, implies consume.
1347          * return length of payload (without type field)
1348          */
1349         type = buffer_get_char(&active_state->incoming_packet);
1350         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1351                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1352         if (type == SSH2_MSG_NEWKEYS)
1353                 set_newkeys(MODE_IN);
1354         else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1355             !active_state->server_side)
1356                 packet_enable_delayed_compress();
1357 #ifdef PACKET_DEBUG
1358         fprintf(stderr, "read/plain[%d]:\r\n", type);
1359         buffer_dump(&active_state->incoming_packet);
1360 #endif
1361         /* reset for next packet */
1362         active_state->packlen = 0;
1363         return type;
1364 }
1365
1366 int
1367 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1368 {
1369         u_int reason, seqnr;
1370         u_char type;
1371         char *msg;
1372
1373         for (;;) {
1374                 if (compat20) {
1375                         type = packet_read_poll2(seqnr_p);
1376                         if (type) {
1377                                 active_state->keep_alive_timeouts = 0;
1378                                 DBG(debug("received packet type %d", type));
1379                         }
1380                         switch (type) {
1381                         case SSH2_MSG_IGNORE:
1382                                 debug3("Received SSH2_MSG_IGNORE");
1383                                 break;
1384                         case SSH2_MSG_DEBUG:
1385                                 packet_get_char();
1386                                 msg = packet_get_string(NULL);
1387                                 debug("Remote: %.900s", msg);
1388                                 xfree(msg);
1389                                 msg = packet_get_string(NULL);
1390                                 xfree(msg);
1391                                 break;
1392                         case SSH2_MSG_DISCONNECT:
1393                                 reason = packet_get_int();
1394                                 msg = packet_get_string(NULL);
1395                                 logit("Received disconnect from %s: %u: %.400s",
1396                                     get_remote_ipaddr(), reason, msg);
1397                                 xfree(msg);
1398                                 cleanup_exit(255);
1399                                 break;
1400                         case SSH2_MSG_UNIMPLEMENTED:
1401                                 seqnr = packet_get_int();
1402                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1403                                     seqnr);
1404                                 break;
1405                         default:
1406                                 return type;
1407                         }
1408                 } else {
1409                         type = packet_read_poll1();
1410                         switch (type) {
1411                         case SSH_MSG_IGNORE:
1412                                 break;
1413                         case SSH_MSG_DEBUG:
1414                                 msg = packet_get_string(NULL);
1415                                 debug("Remote: %.900s", msg);
1416                                 xfree(msg);
1417                                 break;
1418                         case SSH_MSG_DISCONNECT:
1419                                 msg = packet_get_string(NULL);
1420                                 logit("Received disconnect from %s: %.400s",
1421                                     get_remote_ipaddr(), msg);
1422                                 cleanup_exit(255);
1423                                 break;
1424                         default:
1425                                 if (type)
1426                                         DBG(debug("received packet type %d", type));
1427                                 return type;
1428                         }
1429                 }
1430         }
1431 }
1432
1433 int
1434 packet_read_poll(void)
1435 {
1436         return packet_read_poll_seqnr(NULL);
1437 }
1438
1439 /*
1440  * Buffers the given amount of input characters.  This is intended to be used
1441  * together with packet_read_poll.
1442  */
1443
1444 void
1445 packet_process_incoming(const char *buf, u_int len)
1446 {
1447         if (active_state->packet_discard) {
1448                 active_state->keep_alive_timeouts = 0; /* ?? */
1449                 if (len >= active_state->packet_discard)
1450                         packet_stop_discard();
1451                 active_state->packet_discard -= len;
1452                 return;
1453         }
1454         buffer_append(&active_state->input, buf, len);
1455 }
1456
1457 /* Returns a character from the packet. */
1458
1459 u_int
1460 packet_get_char(void)
1461 {
1462         char ch;
1463
1464         buffer_get(&active_state->incoming_packet, &ch, 1);
1465         return (u_char) ch;
1466 }
1467
1468 /* Returns an integer from the packet data. */
1469
1470 u_int
1471 packet_get_int(void)
1472 {
1473         return buffer_get_int(&active_state->incoming_packet);
1474 }
1475
1476 /* Returns an 64 bit integer from the packet data. */
1477
1478 u_int64_t
1479 packet_get_int64(void)
1480 {
1481         return buffer_get_int64(&active_state->incoming_packet);
1482 }
1483
1484 /*
1485  * Returns an arbitrary precision integer from the packet data.  The integer
1486  * must have been initialized before this call.
1487  */
1488
1489 void
1490 packet_get_bignum(BIGNUM * value)
1491 {
1492         buffer_get_bignum(&active_state->incoming_packet, value);
1493 }
1494
1495 void
1496 packet_get_bignum2(BIGNUM * value)
1497 {
1498         buffer_get_bignum2(&active_state->incoming_packet, value);
1499 }
1500
1501 void *
1502 packet_get_raw(u_int *length_ptr)
1503 {
1504         u_int bytes = buffer_len(&active_state->incoming_packet);
1505
1506         if (length_ptr != NULL)
1507                 *length_ptr = bytes;
1508         return buffer_ptr(&active_state->incoming_packet);
1509 }
1510
1511 int
1512 packet_remaining(void)
1513 {
1514         return buffer_len(&active_state->incoming_packet);
1515 }
1516
1517 /*
1518  * Returns a string from the packet data.  The string is allocated using
1519  * xmalloc; it is the responsibility of the calling program to free it when
1520  * no longer needed.  The length_ptr argument may be NULL, or point to an
1521  * integer into which the length of the string is stored.
1522  */
1523
1524 void *
1525 packet_get_string(u_int *length_ptr)
1526 {
1527         return buffer_get_string(&active_state->incoming_packet, length_ptr);
1528 }
1529
1530 void *
1531 packet_get_string_ptr(u_int *length_ptr)
1532 {
1533         return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1534 }
1535
1536 /*
1537  * Sends a diagnostic message from the server to the client.  This message
1538  * can be sent at any time (but not while constructing another message). The
1539  * message is printed immediately, but only if the client is being executed
1540  * in verbose mode.  These messages are primarily intended to ease debugging
1541  * authentication problems.   The length of the formatted message must not
1542  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1543  */
1544
1545 void
1546 packet_send_debug(const char *fmt,...)
1547 {
1548         char buf[1024];
1549         va_list args;
1550
1551         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1552                 return;
1553
1554         va_start(args, fmt);
1555         vsnprintf(buf, sizeof(buf), fmt, args);
1556         va_end(args);
1557
1558         if (compat20) {
1559                 packet_start(SSH2_MSG_DEBUG);
1560                 packet_put_char(0);     /* bool: always display */
1561                 packet_put_cstring(buf);
1562                 packet_put_cstring("");
1563         } else {
1564                 packet_start(SSH_MSG_DEBUG);
1565                 packet_put_cstring(buf);
1566         }
1567         packet_send();
1568         packet_write_wait();
1569 }
1570
1571 /*
1572  * Logs the error plus constructs and sends a disconnect packet, closes the
1573  * connection, and exits.  This function never returns. The error message
1574  * should not contain a newline.  The length of the formatted message must
1575  * not exceed 1024 bytes.
1576  */
1577
1578 void
1579 packet_disconnect(const char *fmt,...)
1580 {
1581         char buf[1024];
1582         va_list args;
1583         static int disconnecting = 0;
1584
1585         if (disconnecting)      /* Guard against recursive invocations. */
1586                 fatal("packet_disconnect called recursively.");
1587         disconnecting = 1;
1588
1589         /*
1590          * Format the message.  Note that the caller must make sure the
1591          * message is of limited size.
1592          */
1593         va_start(args, fmt);
1594         vsnprintf(buf, sizeof(buf), fmt, args);
1595         va_end(args);
1596
1597         /* Display the error locally */
1598         logit("Disconnecting: %.100s", buf);
1599
1600         /* Send the disconnect message to the other side, and wait for it to get sent. */
1601         if (compat20) {
1602                 packet_start(SSH2_MSG_DISCONNECT);
1603                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1604                 packet_put_cstring(buf);
1605                 packet_put_cstring("");
1606         } else {
1607                 packet_start(SSH_MSG_DISCONNECT);
1608                 packet_put_cstring(buf);
1609         }
1610         packet_send();
1611         packet_write_wait();
1612
1613         /* Stop listening for connections. */
1614         channel_close_all();
1615
1616         /* Close the connection. */
1617         packet_close();
1618         cleanup_exit(255);
1619 }
1620
1621 /* Checks if there is any buffered output, and tries to write some of the output. */
1622
1623 void
1624 packet_write_poll(void)
1625 {
1626         int len = buffer_len(&active_state->output);
1627
1628         if (len > 0) {
1629                 len = write(active_state->connection_out,
1630                     buffer_ptr(&active_state->output), len);
1631                 if (len == -1) {
1632                         if (errno == EINTR || errno == EAGAIN ||
1633                             errno == EWOULDBLOCK)
1634                                 return;
1635                         fatal("Write failed: %.100s", strerror(errno));
1636                 }
1637                 if (len == 0)
1638                         fatal("Write connection closed");
1639                 buffer_consume(&active_state->output, len);
1640         }
1641 }
1642
1643
1644 /*
1645  * Calls packet_write_poll repeatedly until all pending output data has been
1646  * written.
1647  */
1648
1649 void
1650 packet_write_wait(void)
1651 {
1652         fd_set *setp;
1653         int ret, ms_remain;
1654         struct timeval start, timeout, *timeoutp = NULL;
1655
1656         setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1657             NFDBITS), sizeof(fd_mask));
1658         packet_write_poll();
1659         while (packet_have_data_to_write()) {
1660                 memset(setp, 0, howmany(active_state->connection_out + 1,
1661                     NFDBITS) * sizeof(fd_mask));
1662                 FD_SET(active_state->connection_out, setp);
1663
1664                 if (active_state->packet_timeout_ms > 0) {
1665                         ms_remain = active_state->packet_timeout_ms;
1666                         timeoutp = &timeout;
1667                 }
1668                 for (;;) {
1669                         if (active_state->packet_timeout_ms != -1) {
1670                                 ms_to_timeval(&timeout, ms_remain);
1671                                 gettimeofday(&start, NULL);
1672                         }
1673                         if ((ret = select(active_state->connection_out + 1,
1674                             NULL, setp, NULL, timeoutp)) >= 0)
1675                                 break;
1676                         if (errno != EAGAIN && errno != EINTR &&
1677                             errno != EWOULDBLOCK)
1678                                 break;
1679                         if (active_state->packet_timeout_ms == -1)
1680                                 continue;
1681                         ms_subtract_diff(&start, &ms_remain);
1682                         if (ms_remain <= 0) {
1683                                 ret = 0;
1684                                 break;
1685                         }
1686                 }
1687                 if (ret == 0) {
1688                         logit("Connection to %.200s timed out while "
1689                             "waiting to write", get_remote_ipaddr());
1690                         cleanup_exit(255);
1691                 }
1692                 packet_write_poll();
1693         }
1694         xfree(setp);
1695 }
1696
1697 /* Returns true if there is buffered data to write to the connection. */
1698
1699 int
1700 packet_have_data_to_write(void)
1701 {
1702         return buffer_len(&active_state->output) != 0;
1703 }
1704
1705 /* Returns true if there is not too much data to write to the connection. */
1706
1707 int
1708 packet_not_very_much_data_to_write(void)
1709 {
1710         if (active_state->interactive_mode)
1711                 return buffer_len(&active_state->output) < 16384;
1712         else
1713                 return buffer_len(&active_state->output) < 128 * 1024;
1714 }
1715
1716
1717 static void
1718 packet_set_tos(int interactive)
1719 {
1720 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1721         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1722
1723         if (!packet_connection_is_on_socket() ||
1724             !packet_connection_is_ipv4())
1725                 return;
1726         if (setsockopt(active_state->connection_in, IPPROTO_IP, IP_TOS, &tos,
1727             sizeof(tos)) < 0)
1728                 error("setsockopt IP_TOS %d: %.100s:",
1729                     tos, strerror(errno));
1730 #endif
1731 }
1732
1733 /* Informs that the current session is interactive.  Sets IP flags for that. */
1734
1735 void
1736 packet_set_interactive(int interactive)
1737 {
1738         static int called = 0;
1739
1740         if (called)
1741                 return;
1742         called = 1;
1743
1744         /* Record that we are in interactive mode. */
1745         active_state->interactive_mode = interactive;
1746
1747         /* Only set socket options if using a socket.  */
1748         if (!packet_connection_is_on_socket())
1749                 return;
1750         set_nodelay(active_state->connection_in);
1751         packet_set_tos(interactive);
1752 }
1753
1754 /* Returns true if the current connection is interactive. */
1755
1756 int
1757 packet_is_interactive(void)
1758 {
1759         return active_state->interactive_mode;
1760 }
1761
1762 int
1763 packet_set_maxsize(u_int s)
1764 {
1765         static int called = 0;
1766
1767         if (called) {
1768                 logit("packet_set_maxsize: called twice: old %d new %d",
1769                     active_state->max_packet_size, s);
1770                 return -1;
1771         }
1772         if (s < 4 * 1024 || s > 1024 * 1024) {
1773                 logit("packet_set_maxsize: bad size %d", s);
1774                 return -1;
1775         }
1776         called = 1;
1777         debug("packet_set_maxsize: setting to %d", s);
1778         active_state->max_packet_size = s;
1779         return s;
1780 }
1781
1782 int
1783 packet_inc_alive_timeouts(void)
1784 {
1785         return ++active_state->keep_alive_timeouts;
1786 }
1787
1788 void
1789 packet_set_alive_timeouts(int ka)
1790 {
1791         active_state->keep_alive_timeouts = ka;
1792 }
1793
1794 u_int
1795 packet_get_maxsize(void)
1796 {
1797         return active_state->max_packet_size;
1798 }
1799
1800 /* roundup current message to pad bytes */
1801 void
1802 packet_add_padding(u_char pad)
1803 {
1804         active_state->extra_pad = pad;
1805 }
1806
1807 /*
1808  * 9.2.  Ignored Data Message
1809  *
1810  *   byte      SSH_MSG_IGNORE
1811  *   string    data
1812  *
1813  * All implementations MUST understand (and ignore) this message at any
1814  * time (after receiving the protocol version). No implementation is
1815  * required to send them. This message can be used as an additional
1816  * protection measure against advanced traffic analysis techniques.
1817  */
1818 void
1819 packet_send_ignore(int nbytes)
1820 {
1821         u_int32_t rnd = 0;
1822         int i;
1823
1824         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1825         packet_put_int(nbytes);
1826         for (i = 0; i < nbytes; i++) {
1827                 if (i % 4 == 0)
1828                         rnd = arc4random();
1829                 packet_put_char((u_char)rnd & 0xff);
1830                 rnd >>= 8;
1831         }
1832 }
1833
1834 #define MAX_PACKETS     (1U<<31)
1835 int
1836 packet_need_rekeying(void)
1837 {
1838         if (datafellows & SSH_BUG_NOREKEY)
1839                 return 0;
1840         return
1841             (active_state->p_send.packets > MAX_PACKETS) ||
1842             (active_state->p_read.packets > MAX_PACKETS) ||
1843             (active_state->max_blocks_out &&
1844                 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1845             (active_state->max_blocks_in &&
1846                 (active_state->p_read.blocks > active_state->max_blocks_in));
1847 }
1848
1849 void
1850 packet_set_rekey_limit(u_int32_t bytes)
1851 {
1852         active_state->rekey_limit = bytes;
1853 }
1854
1855 void
1856 packet_set_server(void)
1857 {
1858         active_state->server_side = 1;
1859 }
1860
1861 void
1862 packet_set_authenticated(void)
1863 {
1864         active_state->after_authentication = 1;
1865 }
1866
1867 void *
1868 packet_get_input(void)
1869 {
1870         return (void *)&active_state->input;
1871 }
1872
1873 void *
1874 packet_get_output(void)
1875 {
1876         return (void *)&active_state->output;
1877 }
1878
1879 void *
1880 packet_get_newkeys(int mode)
1881 {
1882         return (void *)active_state->newkeys[mode];
1883 }