crypto/openssh/packet.c

   1 /* $OpenBSD: packet.c,v 1.176 2012/01/25 19:40:09 markus Exp $ */
   2 /* $FreeBSD$ */
   3 /*
   4  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   5  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   6  *                    All rights reserved
   7  * This file contains code implementing the packet protocol and communication
   8  * with the other side.  This same code is used both on client and server side.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  *
  17  * SSH2 packet format added by Markus Friedl.
  18  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  19  *
  20  * Redistribution and use in source and binary forms, with or without
  21  * modification, are permitted provided that the following conditions
  22  * are met:
  23  * 1. Redistributions of source code must retain the above copyright
  24  *    notice, this list of conditions and the following disclaimer.
  25  * 2. Redistributions in binary form must reproduce the above copyright
  26  *    notice, this list of conditions and the following disclaimer in the
  27  *    documentation and/or other materials provided with the distribution.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  30  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  31  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  32  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  33  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  34  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  38  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  */
  40
  41 #include "includes.h"
  42
  43 #include <sys/types.h>
  44 #include "openbsd-compat/sys-queue.h"
  45 #include <sys/param.h>
  46 #include <sys/socket.h>
  47 #ifdef HAVE_SYS_TIME_H
  48 # include <sys/time.h>
  49 #endif
  50
  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 #include "roaming.h"
  82
  83 #ifdef PACKET_DEBUG
  84 #define DBG(x) x
  85 #else
  86 #define DBG(x)
  87 #endif
  88
  89 #define PACKET_MAX_SIZE (256 * 1024)
  90
  91 struct packet_state {
  92         u_int32_t seqnr;
  93         u_int32_t packets;
  94         u_int64_t blocks;
  95         u_int64_t bytes;
  96 };
  97
  98 struct packet {
  99         TAILQ_ENTRY(packet) next;
 100         u_char type;
 101         Buffer payload;
 102 };
 103
 104 struct session_state {
 105         /*
 106          * This variable contains the file descriptors used for
 107          * communicating with the other side.  connection_in is used for
 108          * reading; connection_out for writing.  These can be the same
 109          * descriptor, in which case it is assumed to be a socket.
 110          */
 111         int connection_in;
 112         int connection_out;
 113
 114         /* Protocol flags for the remote side. */
 115         u_int remote_protocol_flags;
 116
 117         /* Encryption context for receiving data.  Only used for decryption. */
 118         CipherContext receive_context;
 119
 120         /* Encryption context for sending data.  Only used for encryption. */
 121         CipherContext send_context;
 122
 123         /* Buffer for raw input data from the socket. */
 124         Buffer input;
 125
 126         /* Buffer for raw output data going to the socket. */
 127         Buffer output;
 128
 129         /* Buffer for the partial outgoing packet being constructed. */
 130         Buffer outgoing_packet;
 131
 132         /* Buffer for the incoming packet currently being processed. */
 133         Buffer incoming_packet;
 134
 135         /* Scratch buffer for packet compression/decompression. */
 136         Buffer compression_buffer;
 137         int compression_buffer_ready;
 138
 139         /*
 140          * Flag indicating whether packet compression/decompression is
 141          * enabled.
 142          */
 143         int packet_compression;
 144
 145         /* default maximum packet size */
 146         u_int max_packet_size;
 147
 148         /* Flag indicating whether this module has been initialized. */
 149         int initialized;
 150
 151         /* Set to true if the connection is interactive. */
 152         int interactive_mode;
 153
 154         /* Set to true if we are the server side. */
 155         int server_side;
 156
 157         /* Set to true if we are authenticated. */
 158         int after_authentication;
 159
 160         int keep_alive_timeouts;
 161
 162         /* The maximum time that we will wait to send or receive a packet */
 163         int packet_timeout_ms;
 164
 165         /* Session key information for Encryption and MAC */
 166         Newkeys *newkeys[MODE_MAX];
 167         struct packet_state p_read, p_send;
 168
 169         u_int64_t max_blocks_in, max_blocks_out;
 170         u_int32_t rekey_limit;
 171
 172         /* Session key for protocol v1 */
 173         u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
 174         u_int ssh1_keylen;
 175
 176         /* roundup current message to extra_pad bytes */
 177         u_char extra_pad;
 178
 179         /* XXX discard incoming data after MAC error */
 180         u_int packet_discard;
 181         Mac *packet_discard_mac;
 182
 183         /* Used in packet_read_poll2() */
 184         u_int packlen;
 185
 186         /* Used in packet_send2 */
 187         int rekeying;
 188
 189         /* Used in packet_set_interactive */
 190         int set_interactive_called;
 191
 192         /* Used in packet_set_maxsize */
 193         int set_maxsize_called;
 194
 195         TAILQ_HEAD(, packet) outgoing;
 196 };
 197
 198 static struct session_state *active_state, *backup_state;
 199 #ifdef  NONE_CIPHER_ENABLED
 200 static int rekey_requested = 0;
 201 #endif
 202
 203 static struct session_state *
 204 alloc_session_state(void)
 205 {
 206         struct session_state *s = xcalloc(1, sizeof(*s));
 207
 208         s->connection_in = -1;
 209         s->connection_out = -1;
 210         s->max_packet_size = 32768;
 211         s->packet_timeout_ms = -1;
 212         return s;
 213 }
 214
 215 /*
 216  * Sets the descriptors used for communication.  Disables encryption until
 217  * packet_set_encryption_key is called.
 218  */
 219 void
 220 packet_set_connection(int fd_in, int fd_out)
 221 {
 222         Cipher *none = cipher_by_name("none");
 223
 224         if (none == NULL)
 225                 fatal("packet_set_connection: cannot load cipher 'none'");
 226         if (active_state == NULL)
 227                 active_state = alloc_session_state();
 228         active_state->connection_in = fd_in;
 229         active_state->connection_out = fd_out;
 230         cipher_init(&active_state->send_context, none, (const u_char *)"",
 231             0, NULL, 0, CIPHER_ENCRYPT);
 232         cipher_init(&active_state->receive_context, none, (const u_char *)"",
 233             0, NULL, 0, CIPHER_DECRYPT);
 234         active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
 235         if (!active_state->initialized) {
 236                 active_state->initialized = 1;
 237                 buffer_init(&active_state->input);
 238                 buffer_init(&active_state->output);
 239                 buffer_init(&active_state->outgoing_packet);
 240                 buffer_init(&active_state->incoming_packet);
 241                 TAILQ_INIT(&active_state->outgoing);
 242                 active_state->p_send.packets = active_state->p_read.packets = 0;
 243         }
 244 }
 245
 246 void
 247 packet_set_timeout(int timeout, int count)
 248 {
 249         if (timeout <= 0 || count <= 0) {
 250                 active_state->packet_timeout_ms = -1;
 251                 return;
 252         }
 253         if ((INT_MAX / 1000) / count < timeout)
 254                 active_state->packet_timeout_ms = INT_MAX;
 255         else
 256                 active_state->packet_timeout_ms = timeout * count * 1000;
 257 }
 258
 259 static void
 260 packet_stop_discard(void)
 261 {
 262         if (active_state->packet_discard_mac) {
 263                 char buf[1024];
 264
 265                 memset(buf, 'a', sizeof(buf));
 266                 while (buffer_len(&active_state->incoming_packet) <
 267                     PACKET_MAX_SIZE)
 268                         buffer_append(&active_state->incoming_packet, buf,
 269                             sizeof(buf));
 270                 (void) mac_compute(active_state->packet_discard_mac,
 271                     active_state->p_read.seqnr,
 272                     buffer_ptr(&active_state->incoming_packet),
 273                     PACKET_MAX_SIZE);
 274         }
 275         logit("Finished discarding for %.200s", get_remote_ipaddr());
 276         cleanup_exit(255);
 277 }
 278
 279 static void
 280 packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
 281 {
 282         if (enc == NULL || !cipher_is_cbc(enc->cipher))
 283                 packet_disconnect("Packet corrupt");
 284         if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
 285                 active_state->packet_discard_mac = mac;
 286         if (buffer_len(&active_state->input) >= discard)
 287                 packet_stop_discard();
 288         active_state->packet_discard = discard -
 289             buffer_len(&active_state->input);
 290 }
 291
 292 /* Returns 1 if remote host is connected via socket, 0 if not. */
 293
 294 int
 295 packet_connection_is_on_socket(void)
 296 {
 297         struct sockaddr_storage from, to;
 298         socklen_t fromlen, tolen;
 299
 300         /* filedescriptors in and out are the same, so it's a socket */
 301         if (active_state->connection_in == active_state->connection_out)
 302                 return 1;
 303         fromlen = sizeof(from);
 304         memset(&from, 0, sizeof(from));
 305         if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
 306             &fromlen) < 0)
 307                 return 0;
 308         tolen = sizeof(to);
 309         memset(&to, 0, sizeof(to));
 310         if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
 311             &tolen) < 0)
 312                 return 0;
 313         if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
 314                 return 0;
 315         if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
 316                 return 0;
 317         return 1;
 318 }
 319
 320 /*
 321  * Exports an IV from the CipherContext required to export the key
 322  * state back from the unprivileged child to the privileged parent
 323  * process.
 324  */
 325
 326 void
 327 packet_get_keyiv(int mode, u_char *iv, u_int len)
 328 {
 329         CipherContext *cc;
 330
 331         if (mode == MODE_OUT)
 332                 cc = &active_state->send_context;
 333         else
 334                 cc = &active_state->receive_context;
 335
 336         cipher_get_keyiv(cc, iv, len);
 337 }
 338
 339 int
 340 packet_get_keycontext(int mode, u_char *dat)
 341 {
 342         CipherContext *cc;
 343
 344         if (mode == MODE_OUT)
 345                 cc = &active_state->send_context;
 346         else
 347                 cc = &active_state->receive_context;
 348
 349         return (cipher_get_keycontext(cc, dat));
 350 }
 351
 352 void
 353 packet_set_keycontext(int mode, u_char *dat)
 354 {
 355         CipherContext *cc;
 356
 357         if (mode == MODE_OUT)
 358                 cc = &active_state->send_context;
 359         else
 360                 cc = &active_state->receive_context;
 361
 362         cipher_set_keycontext(cc, dat);
 363 }
 364
 365 int
 366 packet_get_keyiv_len(int mode)
 367 {
 368         CipherContext *cc;
 369
 370         if (mode == MODE_OUT)
 371                 cc = &active_state->send_context;
 372         else
 373                 cc = &active_state->receive_context;
 374
 375         return (cipher_get_keyiv_len(cc));
 376 }
 377
 378 void
 379 packet_set_iv(int mode, u_char *dat)
 380 {
 381         CipherContext *cc;
 382
 383         if (mode == MODE_OUT)
 384                 cc = &active_state->send_context;
 385         else
 386                 cc = &active_state->receive_context;
 387
 388         cipher_set_keyiv(cc, dat);
 389 }
 390
 391 int
 392 packet_get_ssh1_cipher(void)
 393 {
 394         return (cipher_get_number(active_state->receive_context.cipher));
 395 }
 396
 397 void
 398 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks,
 399     u_int32_t *packets, u_int64_t *bytes)
 400 {
 401         struct packet_state *state;
 402
 403         state = (mode == MODE_IN) ?
 404             &active_state->p_read : &active_state->p_send;
 405         if (seqnr)
 406                 *seqnr = state->seqnr;
 407         if (blocks)
 408                 *blocks = state->blocks;
 409         if (packets)
 410                 *packets = state->packets;
 411         if (bytes)
 412                 *bytes = state->bytes;
 413 }
 414
 415 void
 416 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
 417     u_int64_t bytes)
 418 {
 419         struct packet_state *state;
 420
 421         state = (mode == MODE_IN) ?
 422             &active_state->p_read : &active_state->p_send;
 423         state->seqnr = seqnr;
 424         state->blocks = blocks;
 425         state->packets = packets;
 426         state->bytes = bytes;
 427 }
 428
 429 static int
 430 packet_connection_af(void)
 431 {
 432         struct sockaddr_storage to;
 433         socklen_t tolen = sizeof(to);
 434
 435         memset(&to, 0, sizeof(to));
 436         if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
 437             &tolen) < 0)
 438                 return 0;
 439 #ifdef IPV4_IN_IPV6
 440         if (to.ss_family == AF_INET6 &&
 441             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
 442                 return AF_INET;
 443 #endif
 444         return to.ss_family;
 445 }
 446
 447 /* Sets the connection into non-blocking mode. */
 448
 449 void
 450 packet_set_nonblocking(void)
 451 {
 452         /* Set the socket into non-blocking mode. */
 453         set_nonblock(active_state->connection_in);
 454
 455         if (active_state->connection_out != active_state->connection_in)
 456                 set_nonblock(active_state->connection_out);
 457 }
 458
 459 /* Returns the socket used for reading. */
 460
 461 int
 462 packet_get_connection_in(void)
 463 {
 464         return active_state->connection_in;
 465 }
 466
 467 /* Returns the descriptor used for writing. */
 468
 469 int
 470 packet_get_connection_out(void)
 471 {
 472         return active_state->connection_out;
 473 }
 474
 475 /* Closes the connection and clears and frees internal data structures. */
 476
 477 void
 478 packet_close(void)
 479 {
 480         if (!active_state->initialized)
 481                 return;
 482         active_state->initialized = 0;
 483         if (active_state->connection_in == active_state->connection_out) {
 484                 shutdown(active_state->connection_out, SHUT_RDWR);
 485                 close(active_state->connection_out);
 486         } else {
 487                 close(active_state->connection_in);
 488                 close(active_state->connection_out);
 489         }
 490         buffer_free(&active_state->input);
 491         buffer_free(&active_state->output);
 492         buffer_free(&active_state->outgoing_packet);
 493         buffer_free(&active_state->incoming_packet);
 494         if (active_state->compression_buffer_ready) {
 495                 buffer_free(&active_state->compression_buffer);
 496                 buffer_compress_uninit();
 497         }
 498         cipher_cleanup(&active_state->send_context);
 499         cipher_cleanup(&active_state->receive_context);
 500 }
 501
 502 /* Sets remote side protocol flags. */
 503
 504 void
 505 packet_set_protocol_flags(u_int protocol_flags)
 506 {
 507         active_state->remote_protocol_flags = protocol_flags;
 508 }
 509
 510 /* Returns the remote protocol flags set earlier by the above function. */
 511
 512 u_int
 513 packet_get_protocol_flags(void)
 514 {
 515         return active_state->remote_protocol_flags;
 516 }
 517
 518 /*
 519  * Starts packet compression from the next packet on in both directions.
 520  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
 521  */
 522
 523 static void
 524 packet_init_compression(void)
 525 {
 526         if (active_state->compression_buffer_ready == 1)
 527                 return;
 528         active_state->compression_buffer_ready = 1;
 529         buffer_init(&active_state->compression_buffer);
 530 }
 531
 532 void
 533 packet_start_compression(int level)
 534 {
 535         if (active_state->packet_compression && !compat20)
 536                 fatal("Compression already enabled.");
 537         active_state->packet_compression = 1;
 538         packet_init_compression();
 539         buffer_compress_init_send(level);
 540         buffer_compress_init_recv();
 541 }
 542
 543 /*
 544  * Causes any further packets to be encrypted using the given key.  The same
 545  * key is used for both sending and reception.  However, both directions are
 546  * encrypted independently of each other.
 547  */
 548
 549 void
 550 packet_set_encryption_key(const u_char *key, u_int keylen, int number)
 551 {
 552         Cipher *cipher = cipher_by_number(number);
 553
 554         if (cipher == NULL)
 555                 fatal("packet_set_encryption_key: unknown cipher number %d", number);
 556         if (keylen < 20)
 557                 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
 558         if (keylen > SSH_SESSION_KEY_LENGTH)
 559                 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
 560         memcpy(active_state->ssh1_key, key, keylen);
 561         active_state->ssh1_keylen = keylen;
 562         cipher_init(&active_state->send_context, cipher, key, keylen, NULL,
 563             0, CIPHER_ENCRYPT);
 564         cipher_init(&active_state->receive_context, cipher, key, keylen, NULL,
 565             0, CIPHER_DECRYPT);
 566 }
 567
 568 u_int
 569 packet_get_encryption_key(u_char *key)
 570 {
 571         if (key == NULL)
 572                 return (active_state->ssh1_keylen);
 573         memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
 574         return (active_state->ssh1_keylen);
 575 }
 576
 577 /* Start constructing a packet to send. */
 578 void
 579 packet_start(u_char type)
 580 {
 581         u_char buf[9];
 582         int len;
 583
 584         DBG(debug("packet_start[%d]", type));
 585         len = compat20 ? 6 : 9;
 586         memset(buf, 0, len - 1);
 587         buf[len - 1] = type;
 588         buffer_clear(&active_state->outgoing_packet);
 589         buffer_append(&active_state->outgoing_packet, buf, len);
 590 }
 591
 592 /* Append payload. */
 593 void
 594 packet_put_char(int value)
 595 {
 596         char ch = value;
 597
 598         buffer_append(&active_state->outgoing_packet, &ch, 1);
 599 }
 600
 601 void
 602 packet_put_int(u_int value)
 603 {
 604         buffer_put_int(&active_state->outgoing_packet, value);
 605 }
 606
 607 void
 608 packet_put_int64(u_int64_t value)
 609 {
 610         buffer_put_int64(&active_state->outgoing_packet, value);
 611 }
 612
 613 void
 614 packet_put_string(const void *buf, u_int len)
 615 {
 616         buffer_put_string(&active_state->outgoing_packet, buf, len);
 617 }
 618
 619 void
 620 packet_put_cstring(const char *str)
 621 {
 622         buffer_put_cstring(&active_state->outgoing_packet, str);
 623 }
 624
 625 void
 626 packet_put_raw(const void *buf, u_int len)
 627 {
 628         buffer_append(&active_state->outgoing_packet, buf, len);
 629 }
 630
 631 void
 632 packet_put_bignum(BIGNUM * value)
 633 {
 634         buffer_put_bignum(&active_state->outgoing_packet, value);
 635 }
 636
 637 void
 638 packet_put_bignum2(BIGNUM * value)
 639 {
 640         buffer_put_bignum2(&active_state->outgoing_packet, value);
 641 }
 642
 643 #ifdef OPENSSL_HAS_ECC
 644 void
 645 packet_put_ecpoint(const EC_GROUP *curve, const EC_POINT *point)
 646 {
 647         buffer_put_ecpoint(&active_state->outgoing_packet, curve, point);
 648 }
 649 #endif
 650
 651 /*
 652  * Finalizes and sends the packet.  If the encryption key has been set,
 653  * encrypts the packet before sending.
 654  */
 655
 656 static void
 657 packet_send1(void)
 658 {
 659         u_char buf[8], *cp;
 660         int i, padding, len;
 661         u_int checksum;
 662         u_int32_t rnd = 0;
 663
 664         /*
 665          * If using packet compression, compress the payload of the outgoing
 666          * packet.
 667          */
 668         if (active_state->packet_compression) {
 669                 buffer_clear(&active_state->compression_buffer);
 670                 /* Skip padding. */
 671                 buffer_consume(&active_state->outgoing_packet, 8);
 672                 /* padding */
 673                 buffer_append(&active_state->compression_buffer,
 674                     "\0\0\0\0\0\0\0\0", 8);
 675                 buffer_compress(&active_state->outgoing_packet,
 676                     &active_state->compression_buffer);
 677                 buffer_clear(&active_state->outgoing_packet);
 678                 buffer_append(&active_state->outgoing_packet,
 679                     buffer_ptr(&active_state->compression_buffer),
 680                     buffer_len(&active_state->compression_buffer));
 681         }
 682         /* Compute packet length without padding (add checksum, remove padding). */
 683         len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
 684
 685         /* Insert padding. Initialized to zero in packet_start1() */
 686         padding = 8 - len % 8;
 687         if (!active_state->send_context.plaintext) {
 688                 cp = buffer_ptr(&active_state->outgoing_packet);
 689                 for (i = 0; i < padding; i++) {
 690                         if (i % 4 == 0)
 691                                 rnd = arc4random();
 692                         cp[7 - i] = rnd & 0xff;
 693                         rnd >>= 8;
 694                 }
 695         }
 696         buffer_consume(&active_state->outgoing_packet, 8 - padding);
 697
 698         /* Add check bytes. */
 699         checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
 700             buffer_len(&active_state->outgoing_packet));
 701         put_u32(buf, checksum);
 702         buffer_append(&active_state->outgoing_packet, buf, 4);
 703
 704 #ifdef PACKET_DEBUG
 705         fprintf(stderr, "packet_send plain: ");
 706         buffer_dump(&active_state->outgoing_packet);
 707 #endif
 708
 709         /* Append to output. */
 710         put_u32(buf, len);
 711         buffer_append(&active_state->output, buf, 4);
 712         cp = buffer_append_space(&active_state->output,
 713             buffer_len(&active_state->outgoing_packet));
 714         cipher_crypt(&active_state->send_context, cp,
 715             buffer_ptr(&active_state->outgoing_packet),
 716             buffer_len(&active_state->outgoing_packet));
 717
 718 #ifdef PACKET_DEBUG
 719         fprintf(stderr, "encrypted: ");
 720         buffer_dump(&active_state->output);
 721 #endif
 722         active_state->p_send.packets++;
 723         active_state->p_send.bytes += len +
 724             buffer_len(&active_state->outgoing_packet);
 725         buffer_clear(&active_state->outgoing_packet);
 726
 727         /*
 728          * Note that the packet is now only buffered in output.  It won't be
 729          * actually sent until packet_write_wait or packet_write_poll is
 730          * called.
 731          */
 732 }
 733
 734 void
 735 set_newkeys(int mode)
 736 {
 737         Enc *enc;
 738         Mac *mac;
 739         Comp *comp;
 740         CipherContext *cc;
 741         u_int64_t *max_blocks;
 742         int crypt_type;
 743
 744         debug2("set_newkeys: mode %d", mode);
 745
 746         if (mode == MODE_OUT) {
 747                 cc = &active_state->send_context;
 748                 crypt_type = CIPHER_ENCRYPT;
 749                 active_state->p_send.packets = active_state->p_send.blocks = 0;
 750                 max_blocks = &active_state->max_blocks_out;
 751         } else {
 752                 cc = &active_state->receive_context;
 753                 crypt_type = CIPHER_DECRYPT;
 754                 active_state->p_read.packets = active_state->p_read.blocks = 0;
 755                 max_blocks = &active_state->max_blocks_in;
 756         }
 757         if (active_state->newkeys[mode] != NULL) {
 758                 debug("set_newkeys: rekeying");
 759                 cipher_cleanup(cc);
 760                 enc  = &active_state->newkeys[mode]->enc;
 761                 mac  = &active_state->newkeys[mode]->mac;
 762                 comp = &active_state->newkeys[mode]->comp;
 763                 mac_clear(mac);
 764                 xfree(enc->name);
 765                 xfree(enc->iv);
 766                 xfree(enc->key);
 767                 xfree(mac->name);
 768                 xfree(mac->key);
 769                 xfree(comp->name);
 770                 xfree(active_state->newkeys[mode]);
 771         }
 772         active_state->newkeys[mode] = kex_get_newkeys(mode);
 773         if (active_state->newkeys[mode] == NULL)
 774                 fatal("newkeys: no keys for mode %d", mode);
 775         enc  = &active_state->newkeys[mode]->enc;
 776         mac  = &active_state->newkeys[mode]->mac;
 777         comp = &active_state->newkeys[mode]->comp;
 778         if (mac_init(mac) == 0)
 779                 mac->enabled = 1;
 780         DBG(debug("cipher_init_context: %d", mode));
 781         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 782             enc->iv, enc->block_size, crypt_type);
 783         /* Deleting the keys does not gain extra security */
 784         /* memset(enc->iv,  0, enc->block_size);
 785            memset(enc->key, 0, enc->key_len);
 786            memset(mac->key, 0, mac->key_len); */
 787         if ((comp->type == COMP_ZLIB ||
 788             (comp->type == COMP_DELAYED &&
 789              active_state->after_authentication)) && comp->enabled == 0) {
 790                 packet_init_compression();
 791                 if (mode == MODE_OUT)
 792                         buffer_compress_init_send(6);
 793                 else
 794                         buffer_compress_init_recv();
 795                 comp->enabled = 1;
 796         }
 797         /*
 798          * The 2^(blocksize*2) limit is too expensive for 3DES,
 799          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 800          */
 801         if (enc->block_size >= 16)
 802                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 803         else
 804                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 805         if (active_state->rekey_limit)
 806                 *max_blocks = MIN(*max_blocks,
 807                     active_state->rekey_limit / enc->block_size);
 808 }
 809
 810 /*
 811  * Delayed compression for SSH2 is enabled after authentication:
 812  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 813  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 814  */
 815 static void
 816 packet_enable_delayed_compress(void)
 817 {
 818         Comp *comp = NULL;
 819         int mode;
 820
 821         /*
 822          * Remember that we are past the authentication step, so rekeying
 823          * with COMP_DELAYED will turn on compression immediately.
 824          */
 825         active_state->after_authentication = 1;
 826         for (mode = 0; mode < MODE_MAX; mode++) {
 827                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 828                 if (active_state->newkeys[mode] == NULL)
 829                         continue;
 830                 comp = &active_state->newkeys[mode]->comp;
 831                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 832                         packet_init_compression();
 833                         if (mode == MODE_OUT)
 834                                 buffer_compress_init_send(6);
 835                         else
 836                                 buffer_compress_init_recv();
 837                         comp->enabled = 1;
 838                 }
 839         }
 840 }
 841
 842 /*
 843  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 844  */
 845 static void
 846 packet_send2_wrapped(void)
 847 {
 848         u_char type, *cp, *macbuf = NULL;
 849         u_char padlen, pad;
 850         u_int packet_length = 0;
 851         u_int i, len;
 852         u_int32_t rnd = 0;
 853         Enc *enc   = NULL;
 854         Mac *mac   = NULL;
 855         Comp *comp = NULL;
 856         int block_size;
 857
 858         if (active_state->newkeys[MODE_OUT] != NULL) {
 859                 enc  = &active_state->newkeys[MODE_OUT]->enc;
 860                 mac  = &active_state->newkeys[MODE_OUT]->mac;
 861                 comp = &active_state->newkeys[MODE_OUT]->comp;
 862         }
 863         block_size = enc ? enc->block_size : 8;
 864
 865         cp = buffer_ptr(&active_state->outgoing_packet);
 866         type = cp[5];
 867
 868 #ifdef PACKET_DEBUG
 869         fprintf(stderr, "plain:     ");
 870         buffer_dump(&active_state->outgoing_packet);
 871 #endif
 872
 873         if (comp && comp->enabled) {
 874                 len = buffer_len(&active_state->outgoing_packet);
 875                 /* skip header, compress only payload */
 876                 buffer_consume(&active_state->outgoing_packet, 5);
 877                 buffer_clear(&active_state->compression_buffer);
 878                 buffer_compress(&active_state->outgoing_packet,
 879                     &active_state->compression_buffer);
 880                 buffer_clear(&active_state->outgoing_packet);
 881                 buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
 882                 buffer_append(&active_state->outgoing_packet,
 883                     buffer_ptr(&active_state->compression_buffer),
 884                     buffer_len(&active_state->compression_buffer));
 885                 DBG(debug("compression: raw %d compressed %d", len,
 886                     buffer_len(&active_state->outgoing_packet)));
 887         }
 888
 889         /* sizeof (packet_len + pad_len + payload) */
 890         len = buffer_len(&active_state->outgoing_packet);
 891
 892         /*
 893          * calc size of padding, alloc space, get random data,
 894          * minimum padding is 4 bytes
 895          */
 896         padlen = block_size - (len % block_size);
 897         if (padlen < 4)
 898                 padlen += block_size;
 899         if (active_state->extra_pad) {
 900                 /* will wrap if extra_pad+padlen > 255 */
 901                 active_state->extra_pad =
 902                     roundup(active_state->extra_pad, block_size);
 903                 pad = active_state->extra_pad -
 904                     ((len + padlen) % active_state->extra_pad);
 905                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 906                     pad, len, padlen, active_state->extra_pad);
 907                 padlen += pad;
 908                 active_state->extra_pad = 0;
 909         }
 910         cp = buffer_append_space(&active_state->outgoing_packet, padlen);
 911         if (enc && !active_state->send_context.plaintext) {
 912                 /* random padding */
 913                 for (i = 0; i < padlen; i++) {
 914                         if (i % 4 == 0)
 915                                 rnd = arc4random();
 916                         cp[i] = rnd & 0xff;
 917                         rnd >>= 8;
 918                 }
 919         } else {
 920                 /* clear padding */
 921                 memset(cp, 0, padlen);
 922         }
 923         /* packet_length includes payload, padding and padding length field */
 924         packet_length = buffer_len(&active_state->outgoing_packet) - 4;
 925         cp = buffer_ptr(&active_state->outgoing_packet);
 926         put_u32(cp, packet_length);
 927         cp[4] = padlen;
 928         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 929
 930         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 931         if (mac && mac->enabled) {
 932                 macbuf = mac_compute(mac, active_state->p_send.seqnr,
 933                     buffer_ptr(&active_state->outgoing_packet),
 934                     buffer_len(&active_state->outgoing_packet));
 935                 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
 936         }
 937         /* encrypt packet and append to output buffer. */
 938         cp = buffer_append_space(&active_state->output,
 939             buffer_len(&active_state->outgoing_packet));
 940         cipher_crypt(&active_state->send_context, cp,
 941             buffer_ptr(&active_state->outgoing_packet),
 942             buffer_len(&active_state->outgoing_packet));
 943         /* append unencrypted MAC */
 944         if (mac && mac->enabled)
 945                 buffer_append(&active_state->output, macbuf, mac->mac_len);
 946 #ifdef PACKET_DEBUG
 947         fprintf(stderr, "encrypted: ");
 948         buffer_dump(&active_state->output);
 949 #endif
 950         /* increment sequence number for outgoing packets */
 951         if (++active_state->p_send.seqnr == 0)
 952                 logit("outgoing seqnr wraps around");
 953         if (++active_state->p_send.packets == 0)
 954                 if (!(datafellows & SSH_BUG_NOREKEY))
 955                         fatal("XXX too many packets with same key");
 956         active_state->p_send.blocks += (packet_length + 4) / block_size;
 957         active_state->p_send.bytes += packet_length + 4;
 958         buffer_clear(&active_state->outgoing_packet);
 959
 960         if (type == SSH2_MSG_NEWKEYS)
 961                 set_newkeys(MODE_OUT);
 962         else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
 963                 packet_enable_delayed_compress();
 964 }
 965
 966 static void
 967 packet_send2(void)
 968 {
 969         struct packet *p;
 970         u_char type, *cp;
 971
 972         cp = buffer_ptr(&active_state->outgoing_packet);
 973         type = cp[5];
 974
 975         /* during rekeying we can only send key exchange messages */
 976         if (active_state->rekeying) {
 977                 if ((type < SSH2_MSG_TRANSPORT_MIN) ||
 978                     (type > SSH2_MSG_TRANSPORT_MAX) ||
 979                     (type == SSH2_MSG_SERVICE_REQUEST) ||
 980                     (type == SSH2_MSG_SERVICE_ACCEPT)) {
 981                         debug("enqueue packet: %u", type);
 982                         p = xmalloc(sizeof(*p));
 983                         p->type = type;
 984                         memcpy(&p->payload, &active_state->outgoing_packet,
 985                             sizeof(Buffer));
 986                         buffer_init(&active_state->outgoing_packet);
 987                         TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
 988                         return;
 989                 }
 990         }
 991
 992         /* rekeying starts with sending KEXINIT */
 993         if (type == SSH2_MSG_KEXINIT)
 994                 active_state->rekeying = 1;
 995
 996         packet_send2_wrapped();
 997
 998         /* after a NEWKEYS message we can send the complete queue */
 999         if (type == SSH2_MSG_NEWKEYS) {
1000                 active_state->rekeying = 0;
1001                 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
1002                         type = p->type;
1003                         debug("dequeue packet: %u", type);
1004                         buffer_free(&active_state->outgoing_packet);
1005                         memcpy(&active_state->outgoing_packet, &p->payload,
1006                             sizeof(Buffer));
1007                         TAILQ_REMOVE(&active_state->outgoing, p, next);
1008                         xfree(p);
1009                         packet_send2_wrapped();
1010                 }
1011         }
1012 }
1013
1014 void
1015 packet_send(void)
1016 {
1017         if (compat20)
1018                 packet_send2();
1019         else
1020                 packet_send1();
1021         DBG(debug("packet_send done"));
1022 }
1023
1024 /*
1025  * Waits until a packet has been received, and returns its type.  Note that
1026  * no other data is processed until this returns, so this function should not
1027  * be used during the interactive session.
1028  */
1029
1030 int
1031 packet_read_seqnr(u_int32_t *seqnr_p)
1032 {
1033         int type, len, ret, ms_remain, cont;
1034         fd_set *setp;
1035         char buf[8192];
1036         struct timeval timeout, start, *timeoutp = NULL;
1037
1038         DBG(debug("packet_read()"));
1039
1040         setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1041             NFDBITS), sizeof(fd_mask));
1042
1043         /* Since we are blocking, ensure that all written packets have been sent. */
1044         packet_write_wait();
1045
1046         /* Stay in the loop until we have received a complete packet. */
1047         for (;;) {
1048                 /* Try to read a packet from the buffer. */
1049                 type = packet_read_poll_seqnr(seqnr_p);
1050                 if (!compat20 && (
1051                     type == SSH_SMSG_SUCCESS
1052                     || type == SSH_SMSG_FAILURE
1053                     || type == SSH_CMSG_EOF
1054                     || type == SSH_CMSG_EXIT_CONFIRMATION))
1055                         packet_check_eom();
1056                 /* If we got a packet, return it. */
1057                 if (type != SSH_MSG_NONE) {
1058                         xfree(setp);
1059                         return type;
1060                 }
1061                 /*
1062                  * Otherwise, wait for some data to arrive, add it to the
1063                  * buffer, and try again.
1064                  */
1065                 memset(setp, 0, howmany(active_state->connection_in + 1,
1066                     NFDBITS) * sizeof(fd_mask));
1067                 FD_SET(active_state->connection_in, setp);
1068
1069                 if (active_state->packet_timeout_ms > 0) {
1070                         ms_remain = active_state->packet_timeout_ms;
1071                         timeoutp = &timeout;
1072                 }
1073                 /* Wait for some data to arrive. */
1074                 for (;;) {
1075                         if (active_state->packet_timeout_ms != -1) {
1076                                 ms_to_timeval(&timeout, ms_remain);
1077                                 gettimeofday(&start, NULL);
1078                         }
1079                         if ((ret = select(active_state->connection_in + 1, setp,
1080                             NULL, NULL, timeoutp)) >= 0)
1081                                 break;
1082                         if (errno != EAGAIN && errno != EINTR &&
1083                             errno != EWOULDBLOCK)
1084                                 break;
1085                         if (active_state->packet_timeout_ms == -1)
1086                                 continue;
1087                         ms_subtract_diff(&start, &ms_remain);
1088                         if (ms_remain <= 0) {
1089                                 ret = 0;
1090                                 break;
1091                         }
1092                 }
1093                 if (ret == 0) {
1094                         logit("Connection to %.200s timed out while "
1095                             "waiting to read", get_remote_ipaddr());
1096                         cleanup_exit(255);
1097                 }
1098                 /* Read data from the socket. */
1099                 do {
1100                         cont = 0;
1101                         len = roaming_read(active_state->connection_in, buf,
1102                             sizeof(buf), &cont);
1103                 } while (len == 0 && cont);
1104                 if (len == 0) {
1105                         logit("Connection closed by %.200s", get_remote_ipaddr());
1106                         cleanup_exit(255);
1107                 }
1108                 if (len < 0)
1109                         fatal("Read from socket failed: %.100s", strerror(errno));
1110                 /* Append it to the buffer. */
1111                 packet_process_incoming(buf, len);
1112         }
1113         /* NOTREACHED */
1114 }
1115
1116 int
1117 packet_read(void)
1118 {
1119         return packet_read_seqnr(NULL);
1120 }
1121
1122 /*
1123  * Waits until a packet has been received, verifies that its type matches
1124  * that given, and gives a fatal error and exits if there is a mismatch.
1125  */
1126
1127 void
1128 packet_read_expect(int expected_type)
1129 {
1130         int type;
1131
1132         type = packet_read();
1133         if (type != expected_type)
1134                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1135                     expected_type, type);
1136 }
1137
1138 /* Checks if a full packet is available in the data received so far via
1139  * packet_process_incoming.  If so, reads the packet; otherwise returns
1140  * SSH_MSG_NONE.  This does not wait for data from the connection.
1141  *
1142  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1143  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1144  * to higher levels.
1145  */
1146
1147 static int
1148 packet_read_poll1(void)
1149 {
1150         u_int len, padded_len;
1151         u_char *cp, type;
1152         u_int checksum, stored_checksum;
1153
1154         /* Check if input size is less than minimum packet size. */
1155         if (buffer_len(&active_state->input) < 4 + 8)
1156                 return SSH_MSG_NONE;
1157         /* Get length of incoming packet. */
1158         cp = buffer_ptr(&active_state->input);
1159         len = get_u32(cp);
1160         if (len < 1 + 2 + 2 || len > 256 * 1024)
1161                 packet_disconnect("Bad packet length %u.", len);
1162         padded_len = (len + 8) & ~7;
1163
1164         /* Check if the packet has been entirely received. */
1165         if (buffer_len(&active_state->input) < 4 + padded_len)
1166                 return SSH_MSG_NONE;
1167
1168         /* The entire packet is in buffer. */
1169
1170         /* Consume packet length. */
1171         buffer_consume(&active_state->input, 4);
1172
1173         /*
1174          * Cryptographic attack detector for ssh
1175          * (C)1998 CORE-SDI, Buenos Aires Argentina
1176          * Ariel Futoransky(futo@core-sdi.com)
1177          */
1178         if (!active_state->receive_context.plaintext) {
1179                 switch (detect_attack(buffer_ptr(&active_state->input),
1180                     padded_len)) {
1181                 case DEATTACK_DETECTED:
1182                         packet_disconnect("crc32 compensation attack: "
1183                             "network attack detected");
1184                 case DEATTACK_DOS_DETECTED:
1185                         packet_disconnect("deattack denial of "
1186                             "service detected");
1187                 }
1188         }
1189
1190         /* Decrypt data to incoming_packet. */
1191         buffer_clear(&active_state->incoming_packet);
1192         cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1193         cipher_crypt(&active_state->receive_context, cp,
1194             buffer_ptr(&active_state->input), padded_len);
1195
1196         buffer_consume(&active_state->input, padded_len);
1197
1198 #ifdef PACKET_DEBUG
1199         fprintf(stderr, "read_poll plain: ");
1200         buffer_dump(&active_state->incoming_packet);
1201 #endif
1202
1203         /* Compute packet checksum. */
1204         checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1205             buffer_len(&active_state->incoming_packet) - 4);
1206
1207         /* Skip padding. */
1208         buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1209
1210         /* Test check bytes. */
1211         if (len != buffer_len(&active_state->incoming_packet))
1212                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1213                     len, buffer_len(&active_state->incoming_packet));
1214
1215         cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1216         stored_checksum = get_u32(cp);
1217         if (checksum != stored_checksum)
1218                 packet_disconnect("Corrupted check bytes on input.");
1219         buffer_consume_end(&active_state->incoming_packet, 4);
1220
1221         if (active_state->packet_compression) {
1222                 buffer_clear(&active_state->compression_buffer);
1223                 buffer_uncompress(&active_state->incoming_packet,
1224                     &active_state->compression_buffer);
1225                 buffer_clear(&active_state->incoming_packet);
1226                 buffer_append(&active_state->incoming_packet,
1227                     buffer_ptr(&active_state->compression_buffer),
1228                     buffer_len(&active_state->compression_buffer));
1229         }
1230         active_state->p_read.packets++;
1231         active_state->p_read.bytes += padded_len + 4;
1232         type = buffer_get_char(&active_state->incoming_packet);
1233         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1234                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1235         return type;
1236 }
1237
1238 static int
1239 packet_read_poll2(u_int32_t *seqnr_p)
1240 {
1241         u_int padlen, need;
1242         u_char *macbuf, *cp, type;
1243         u_int maclen, block_size;
1244         Enc *enc   = NULL;
1245         Mac *mac   = NULL;
1246         Comp *comp = NULL;
1247
1248         if (active_state->packet_discard)
1249                 return SSH_MSG_NONE;
1250
1251         if (active_state->newkeys[MODE_IN] != NULL) {
1252                 enc  = &active_state->newkeys[MODE_IN]->enc;
1253                 mac  = &active_state->newkeys[MODE_IN]->mac;
1254                 comp = &active_state->newkeys[MODE_IN]->comp;
1255         }
1256         maclen = mac && mac->enabled ? mac->mac_len : 0;
1257         block_size = enc ? enc->block_size : 8;
1258
1259         if (active_state->packlen == 0) {
1260                 /*
1261                  * check if input size is less than the cipher block size,
1262                  * decrypt first block and extract length of incoming packet
1263                  */
1264                 if (buffer_len(&active_state->input) < block_size)
1265                         return SSH_MSG_NONE;
1266                 buffer_clear(&active_state->incoming_packet);
1267                 cp = buffer_append_space(&active_state->incoming_packet,
1268                     block_size);
1269                 cipher_crypt(&active_state->receive_context, cp,
1270                     buffer_ptr(&active_state->input), block_size);
1271                 cp = buffer_ptr(&active_state->incoming_packet);
1272
1273                 active_state->packlen = get_u32(cp);
1274                 if (active_state->packlen < 1 + 4 ||
1275                     active_state->packlen > PACKET_MAX_SIZE) {
1276 #ifdef PACKET_DEBUG
1277                         buffer_dump(&active_state->incoming_packet);
1278 #endif
1279                         logit("Bad packet length %u.", active_state->packlen);
1280                         packet_start_discard(enc, mac, active_state->packlen,
1281                             PACKET_MAX_SIZE);
1282                         return SSH_MSG_NONE;
1283                 }
1284                 DBG(debug("input: packet len %u", active_state->packlen+4));
1285                 buffer_consume(&active_state->input, block_size);
1286         }
1287         /* we have a partial packet of block_size bytes */
1288         need = 4 + active_state->packlen - block_size;
1289         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1290             need, maclen));
1291         if (need % block_size != 0) {
1292                 logit("padding error: need %d block %d mod %d",
1293                     need, block_size, need % block_size);
1294                 packet_start_discard(enc, mac, active_state->packlen,
1295                     PACKET_MAX_SIZE - block_size);
1296                 return SSH_MSG_NONE;
1297         }
1298         /*
1299          * check if the entire packet has been received and
1300          * decrypt into incoming_packet
1301          */
1302         if (buffer_len(&active_state->input) < need + maclen)
1303                 return SSH_MSG_NONE;
1304 #ifdef PACKET_DEBUG
1305         fprintf(stderr, "read_poll enc/full: ");
1306         buffer_dump(&active_state->input);
1307 #endif
1308         cp = buffer_append_space(&active_state->incoming_packet, need);
1309         cipher_crypt(&active_state->receive_context, cp,
1310             buffer_ptr(&active_state->input), need);
1311         buffer_consume(&active_state->input, need);
1312         /*
1313          * compute MAC over seqnr and packet,
1314          * increment sequence number for incoming packet
1315          */
1316         if (mac && mac->enabled) {
1317                 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1318                     buffer_ptr(&active_state->incoming_packet),
1319                     buffer_len(&active_state->incoming_packet));
1320                 if (timingsafe_bcmp(macbuf, buffer_ptr(&active_state->input),
1321                     mac->mac_len) != 0) {
1322                         logit("Corrupted MAC on input.");
1323                         if (need > PACKET_MAX_SIZE)
1324                                 fatal("internal error need %d", need);
1325                         packet_start_discard(enc, mac, active_state->packlen,
1326                             PACKET_MAX_SIZE - need);
1327                         return SSH_MSG_NONE;
1328                 }
1329
1330                 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1331                 buffer_consume(&active_state->input, mac->mac_len);
1332         }
1333         /* XXX now it's safe to use fatal/packet_disconnect */
1334         if (seqnr_p != NULL)
1335                 *seqnr_p = active_state->p_read.seqnr;
1336         if (++active_state->p_read.seqnr == 0)
1337                 logit("incoming seqnr wraps around");
1338         if (++active_state->p_read.packets == 0)
1339                 if (!(datafellows & SSH_BUG_NOREKEY))
1340                         fatal("XXX too many packets with same key");
1341         active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1342         active_state->p_read.bytes += active_state->packlen + 4;
1343
1344         /* get padlen */
1345         cp = buffer_ptr(&active_state->incoming_packet);
1346         padlen = cp[4];
1347         DBG(debug("input: padlen %d", padlen));
1348         if (padlen < 4)
1349                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1350
1351         /* skip packet size + padlen, discard padding */
1352         buffer_consume(&active_state->incoming_packet, 4 + 1);
1353         buffer_consume_end(&active_state->incoming_packet, padlen);
1354
1355         DBG(debug("input: len before de-compress %d",
1356             buffer_len(&active_state->incoming_packet)));
1357         if (comp && comp->enabled) {
1358                 buffer_clear(&active_state->compression_buffer);
1359                 buffer_uncompress(&active_state->incoming_packet,
1360                     &active_state->compression_buffer);
1361                 buffer_clear(&active_state->incoming_packet);
1362                 buffer_append(&active_state->incoming_packet,
1363                     buffer_ptr(&active_state->compression_buffer),
1364                     buffer_len(&active_state->compression_buffer));
1365                 DBG(debug("input: len after de-compress %d",
1366                     buffer_len(&active_state->incoming_packet)));
1367         }
1368         /*
1369          * get packet type, implies consume.
1370          * return length of payload (without type field)
1371          */
1372         type = buffer_get_char(&active_state->incoming_packet);
1373         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1374                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1375         if (type == SSH2_MSG_NEWKEYS)
1376                 set_newkeys(MODE_IN);
1377         else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1378             !active_state->server_side)
1379                 packet_enable_delayed_compress();
1380 #ifdef PACKET_DEBUG
1381         fprintf(stderr, "read/plain[%d]:\r\n", type);
1382         buffer_dump(&active_state->incoming_packet);
1383 #endif
1384         /* reset for next packet */
1385         active_state->packlen = 0;
1386         return type;
1387 }
1388
1389 int
1390 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1391 {
1392         u_int reason, seqnr;
1393         u_char type;
1394         char *msg;
1395
1396         for (;;) {
1397                 if (compat20) {
1398                         type = packet_read_poll2(seqnr_p);
1399                         if (type) {
1400                                 active_state->keep_alive_timeouts = 0;
1401                                 DBG(debug("received packet type %d", type));
1402                         }
1403                         switch (type) {
1404                         case SSH2_MSG_IGNORE:
1405                                 debug3("Received SSH2_MSG_IGNORE");
1406                                 break;
1407                         case SSH2_MSG_DEBUG:
1408                                 packet_get_char();
1409                                 msg = packet_get_string(NULL);
1410                                 debug("Remote: %.900s", msg);
1411                                 xfree(msg);
1412                                 msg = packet_get_string(NULL);
1413                                 xfree(msg);
1414                                 break;
1415                         case SSH2_MSG_DISCONNECT:
1416                                 reason = packet_get_int();
1417                                 msg = packet_get_string(NULL);
1418                                 logit("Received disconnect from %s: %u: %.400s",
1419                                     get_remote_ipaddr(), reason, msg);
1420                                 xfree(msg);
1421                                 cleanup_exit(255);
1422                                 break;
1423                         case SSH2_MSG_UNIMPLEMENTED:
1424                                 seqnr = packet_get_int();
1425                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1426                                     seqnr);
1427                                 break;
1428                         default:
1429                                 return type;
1430                         }
1431                 } else {
1432                         type = packet_read_poll1();
1433                         switch (type) {
1434                         case SSH_MSG_IGNORE:
1435                                 break;
1436                         case SSH_MSG_DEBUG:
1437                                 msg = packet_get_string(NULL);
1438                                 debug("Remote: %.900s", msg);
1439                                 xfree(msg);
1440                                 break;
1441                         case SSH_MSG_DISCONNECT:
1442                                 msg = packet_get_string(NULL);
1443                                 logit("Received disconnect from %s: %.400s",
1444                                     get_remote_ipaddr(), msg);
1445                                 cleanup_exit(255);
1446                                 break;
1447                         default:
1448                                 if (type)
1449                                         DBG(debug("received packet type %d", type));
1450                                 return type;
1451                         }
1452                 }
1453         }
1454 }
1455
1456 /*
1457  * Buffers the given amount of input characters.  This is intended to be used
1458  * together with packet_read_poll.
1459  */
1460
1461 void
1462 packet_process_incoming(const char *buf, u_int len)
1463 {
1464         if (active_state->packet_discard) {
1465                 active_state->keep_alive_timeouts = 0; /* ?? */
1466                 if (len >= active_state->packet_discard)
1467                         packet_stop_discard();
1468                 active_state->packet_discard -= len;
1469                 return;
1470         }
1471         buffer_append(&active_state->input, buf, len);
1472 }
1473
1474 /* Returns a character from the packet. */
1475
1476 u_int
1477 packet_get_char(void)
1478 {
1479         char ch;
1480
1481         buffer_get(&active_state->incoming_packet, &ch, 1);
1482         return (u_char) ch;
1483 }
1484
1485 /* Returns an integer from the packet data. */
1486
1487 u_int
1488 packet_get_int(void)
1489 {
1490         return buffer_get_int(&active_state->incoming_packet);
1491 }
1492
1493 /* Returns an 64 bit integer from the packet data. */
1494
1495 u_int64_t
1496 packet_get_int64(void)
1497 {
1498         return buffer_get_int64(&active_state->incoming_packet);
1499 }
1500
1501 /*
1502  * Returns an arbitrary precision integer from the packet data.  The integer
1503  * must have been initialized before this call.
1504  */
1505
1506 void
1507 packet_get_bignum(BIGNUM * value)
1508 {
1509         buffer_get_bignum(&active_state->incoming_packet, value);
1510 }
1511
1512 void
1513 packet_get_bignum2(BIGNUM * value)
1514 {
1515         buffer_get_bignum2(&active_state->incoming_packet, value);
1516 }
1517
1518 #ifdef OPENSSL_HAS_ECC
1519 void
1520 packet_get_ecpoint(const EC_GROUP *curve, EC_POINT *point)
1521 {
1522         buffer_get_ecpoint(&active_state->incoming_packet, curve, point);
1523 }
1524 #endif
1525
1526 void *
1527 packet_get_raw(u_int *length_ptr)
1528 {
1529         u_int bytes = buffer_len(&active_state->incoming_packet);
1530
1531         if (length_ptr != NULL)
1532                 *length_ptr = bytes;
1533         return buffer_ptr(&active_state->incoming_packet);
1534 }
1535
1536 int
1537 packet_remaining(void)
1538 {
1539         return buffer_len(&active_state->incoming_packet);
1540 }
1541
1542 /*
1543  * Returns a string from the packet data.  The string is allocated using
1544  * xmalloc; it is the responsibility of the calling program to free it when
1545  * no longer needed.  The length_ptr argument may be NULL, or point to an
1546  * integer into which the length of the string is stored.
1547  */
1548
1549 void *
1550 packet_get_string(u_int *length_ptr)
1551 {
1552         return buffer_get_string(&active_state->incoming_packet, length_ptr);
1553 }
1554
1555 void *
1556 packet_get_string_ptr(u_int *length_ptr)
1557 {
1558         return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1559 }
1560
1561 /* Ensures the returned string has no embedded \0 characters in it. */
1562 char *
1563 packet_get_cstring(u_int *length_ptr)
1564 {
1565         return buffer_get_cstring(&active_state->incoming_packet, length_ptr);
1566 }
1567
1568 /*
1569  * Sends a diagnostic message from the server to the client.  This message
1570  * can be sent at any time (but not while constructing another message). The
1571  * message is printed immediately, but only if the client is being executed
1572  * in verbose mode.  These messages are primarily intended to ease debugging
1573  * authentication problems.   The length of the formatted message must not
1574  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1575  */
1576
1577 void
1578 packet_send_debug(const char *fmt,...)
1579 {
1580         char buf[1024];
1581         va_list args;
1582
1583         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1584                 return;
1585
1586         va_start(args, fmt);
1587         vsnprintf(buf, sizeof(buf), fmt, args);
1588         va_end(args);
1589
1590         if (compat20) {
1591                 packet_start(SSH2_MSG_DEBUG);
1592                 packet_put_char(0);     /* bool: always display */
1593                 packet_put_cstring(buf);
1594                 packet_put_cstring("");
1595         } else {
1596                 packet_start(SSH_MSG_DEBUG);
1597                 packet_put_cstring(buf);
1598         }
1599         packet_send();
1600         packet_write_wait();
1601 }
1602
1603 /*
1604  * Logs the error plus constructs and sends a disconnect packet, closes the
1605  * connection, and exits.  This function never returns. The error message
1606  * should not contain a newline.  The length of the formatted message must
1607  * not exceed 1024 bytes.
1608  */
1609
1610 void
1611 packet_disconnect(const char *fmt,...)
1612 {
1613         char buf[1024];
1614         va_list args;
1615         static int disconnecting = 0;
1616
1617         if (disconnecting)      /* Guard against recursive invocations. */
1618                 fatal("packet_disconnect called recursively.");
1619         disconnecting = 1;
1620
1621         /*
1622          * Format the message.  Note that the caller must make sure the
1623          * message is of limited size.
1624          */
1625         va_start(args, fmt);
1626         vsnprintf(buf, sizeof(buf), fmt, args);
1627         va_end(args);
1628
1629         /* Display the error locally */
1630         logit("Disconnecting: %.100s", buf);
1631
1632         /* Send the disconnect message to the other side, and wait for it to get sent. */
1633         if (compat20) {
1634                 packet_start(SSH2_MSG_DISCONNECT);
1635                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1636                 packet_put_cstring(buf);
1637                 packet_put_cstring("");
1638         } else {
1639                 packet_start(SSH_MSG_DISCONNECT);
1640                 packet_put_cstring(buf);
1641         }
1642         packet_send();
1643         packet_write_wait();
1644
1645         /* Stop listening for connections. */
1646         channel_close_all();
1647
1648         /* Close the connection. */
1649         packet_close();
1650         cleanup_exit(255);
1651 }
1652
1653 /* Checks if there is any buffered output, and tries to write some of the output. */
1654
1655 void
1656 packet_write_poll(void)
1657 {
1658         int len = buffer_len(&active_state->output);
1659         int cont;
1660
1661         if (len > 0) {
1662                 cont = 0;
1663                 len = roaming_write(active_state->connection_out,
1664                     buffer_ptr(&active_state->output), len, &cont);
1665                 if (len == -1) {
1666                         if (errno == EINTR || errno == EAGAIN ||
1667                             errno == EWOULDBLOCK)
1668                                 return;
1669                         fatal("Write failed: %.100s", strerror(errno));
1670                 }
1671                 if (len == 0 && !cont)
1672                         fatal("Write connection closed");
1673                 buffer_consume(&active_state->output, len);
1674         }
1675 }
1676
1677 /*
1678  * Calls packet_write_poll repeatedly until all pending output data has been
1679  * written.
1680  */
1681
1682 void
1683 packet_write_wait(void)
1684 {
1685         fd_set *setp;
1686         int ret, ms_remain;
1687         struct timeval start, timeout, *timeoutp = NULL;
1688
1689         setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1690             NFDBITS), sizeof(fd_mask));
1691         packet_write_poll();
1692         while (packet_have_data_to_write()) {
1693                 memset(setp, 0, howmany(active_state->connection_out + 1,
1694                     NFDBITS) * sizeof(fd_mask));
1695                 FD_SET(active_state->connection_out, setp);
1696
1697                 if (active_state->packet_timeout_ms > 0) {
1698                         ms_remain = active_state->packet_timeout_ms;
1699                         timeoutp = &timeout;
1700                 }
1701                 for (;;) {
1702                         if (active_state->packet_timeout_ms != -1) {
1703                                 ms_to_timeval(&timeout, ms_remain);
1704                                 gettimeofday(&start, NULL);
1705                         }
1706                         if ((ret = select(active_state->connection_out + 1,
1707                             NULL, setp, NULL, timeoutp)) >= 0)
1708                                 break;
1709                         if (errno != EAGAIN && errno != EINTR &&
1710                             errno != EWOULDBLOCK)
1711                                 break;
1712                         if (active_state->packet_timeout_ms == -1)
1713                                 continue;
1714                         ms_subtract_diff(&start, &ms_remain);
1715                         if (ms_remain <= 0) {
1716                                 ret = 0;
1717                                 break;
1718                         }
1719                 }
1720                 if (ret == 0) {
1721                         logit("Connection to %.200s timed out while "
1722                             "waiting to write", get_remote_ipaddr());
1723                         cleanup_exit(255);
1724                 }
1725                 packet_write_poll();
1726         }
1727         xfree(setp);
1728 }
1729
1730 /* Returns true if there is buffered data to write to the connection. */
1731
1732 int
1733 packet_have_data_to_write(void)
1734 {
1735         return buffer_len(&active_state->output) != 0;
1736 }
1737
1738 /* Returns true if there is not too much data to write to the connection. */
1739
1740 int
1741 packet_not_very_much_data_to_write(void)
1742 {
1743         if (active_state->interactive_mode)
1744                 return buffer_len(&active_state->output) < 16384;
1745         else
1746                 return buffer_len(&active_state->output) < 128 * 1024;
1747 }
1748
1749 static void
1750 packet_set_tos(int tos)
1751 {
1752 #ifndef IP_TOS_IS_BROKEN
1753         if (!packet_connection_is_on_socket())
1754                 return;
1755         switch (packet_connection_af()) {
1756 # ifdef IP_TOS
1757         case AF_INET:
1758                 debug3("%s: set IP_TOS 0x%02x", __func__, tos);
1759                 if (setsockopt(active_state->connection_in,
1760                     IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
1761                         error("setsockopt IP_TOS %d: %.100s:",
1762                             tos, strerror(errno));
1763                 break;
1764 # endif /* IP_TOS */
1765 # ifdef IPV6_TCLASS
1766         case AF_INET6:
1767                 debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos);
1768                 if (setsockopt(active_state->connection_in,
1769                     IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0)
1770                         error("setsockopt IPV6_TCLASS %d: %.100s:",
1771                             tos, strerror(errno));
1772                 break;
1773 # endif /* IPV6_TCLASS */
1774         }
1775 #endif /* IP_TOS_IS_BROKEN */
1776 }
1777
1778 /* Informs that the current session is interactive.  Sets IP flags for that. */
1779
1780 void
1781 packet_set_interactive(int interactive, int qos_interactive, int qos_bulk)
1782 {
1783         if (active_state->set_interactive_called)
1784                 return;
1785         active_state->set_interactive_called = 1;
1786
1787         /* Record that we are in interactive mode. */
1788         active_state->interactive_mode = interactive;
1789
1790         /* Only set socket options if using a socket.  */
1791         if (!packet_connection_is_on_socket())
1792                 return;
1793         set_nodelay(active_state->connection_in);
1794         packet_set_tos(interactive ? qos_interactive : qos_bulk);
1795 }
1796
1797 /* Returns true if the current connection is interactive. */
1798
1799 int
1800 packet_is_interactive(void)
1801 {
1802         return active_state->interactive_mode;
1803 }
1804
1805 int
1806 packet_set_maxsize(u_int s)
1807 {
1808         if (active_state->set_maxsize_called) {
1809                 logit("packet_set_maxsize: called twice: old %d new %d",
1810                     active_state->max_packet_size, s);
1811                 return -1;
1812         }
1813         if (s < 4 * 1024 || s > 1024 * 1024) {
1814                 logit("packet_set_maxsize: bad size %d", s);
1815                 return -1;
1816         }
1817         active_state->set_maxsize_called = 1;
1818         debug("packet_set_maxsize: setting to %d", s);
1819         active_state->max_packet_size = s;
1820         return s;
1821 }
1822
1823 int
1824 packet_inc_alive_timeouts(void)
1825 {
1826         return ++active_state->keep_alive_timeouts;
1827 }
1828
1829 void
1830 packet_set_alive_timeouts(int ka)
1831 {
1832         active_state->keep_alive_timeouts = ka;
1833 }
1834
1835 u_int
1836 packet_get_maxsize(void)
1837 {
1838         return active_state->max_packet_size;
1839 }
1840
1841 /* roundup current message to pad bytes */
1842 void
1843 packet_add_padding(u_char pad)
1844 {
1845         active_state->extra_pad = pad;
1846 }
1847
1848 /*
1849  * 9.2.  Ignored Data Message
1850  *
1851  *   byte      SSH_MSG_IGNORE
1852  *   string    data
1853  *
1854  * All implementations MUST understand (and ignore) this message at any
1855  * time (after receiving the protocol version). No implementation is
1856  * required to send them. This message can be used as an additional
1857  * protection measure against advanced traffic analysis techniques.
1858  */
1859 void
1860 packet_send_ignore(int nbytes)
1861 {
1862         u_int32_t rnd = 0;
1863         int i;
1864
1865         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1866         packet_put_int(nbytes);
1867         for (i = 0; i < nbytes; i++) {
1868                 if (i % 4 == 0)
1869                         rnd = arc4random();
1870                 packet_put_char((u_char)rnd & 0xff);
1871                 rnd >>= 8;
1872         }
1873 }
1874
1875 #ifdef  NONE_CIPHER_ENABLED
1876 void
1877 packet_request_rekeying(void)
1878 {
1879         rekey_requested = 1;
1880 }
1881 #endif
1882
1883 #define MAX_PACKETS     (1U<<31)
1884 int
1885 packet_need_rekeying(void)
1886 {
1887         if (datafellows & SSH_BUG_NOREKEY)
1888                 return 0;
1889 #ifdef  NONE_CIPHER_ENABLED
1890         if (rekey_requested == 1) {
1891                 rekey_requested = 0;
1892                 return 1;
1893         }
1894 #endif
1895         return
1896             (active_state->p_send.packets > MAX_PACKETS) ||
1897             (active_state->p_read.packets > MAX_PACKETS) ||
1898             (active_state->max_blocks_out &&
1899                 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1900             (active_state->max_blocks_in &&
1901                 (active_state->p_read.blocks > active_state->max_blocks_in));
1902 }
1903
1904 void
1905 packet_set_rekey_limit(u_int32_t bytes)
1906 {
1907         active_state->rekey_limit = bytes;
1908 }
1909
1910 void
1911 packet_set_server(void)
1912 {
1913         active_state->server_side = 1;
1914 }
1915
1916 void
1917 packet_set_authenticated(void)
1918 {
1919         active_state->after_authentication = 1;
1920 }
1921
1922 void *
1923 packet_get_input(void)
1924 {
1925         return (void *)&active_state->input;
1926 }
1927
1928 void *
1929 packet_get_output(void)
1930 {
1931         return (void *)&active_state->output;
1932 }
1933
1934 void *
1935 packet_get_newkeys(int mode)
1936 {
1937         return (void *)active_state->newkeys[mode];
1938 }
1939
1940 /*
1941  * Save the state for the real connection, and use a separate state when
1942  * resuming a suspended connection.
1943  */
1944 void
1945 packet_backup_state(void)
1946 {
1947         struct session_state *tmp;
1948
1949         close(active_state->connection_in);
1950         active_state->connection_in = -1;
1951         close(active_state->connection_out);
1952         active_state->connection_out = -1;
1953         if (backup_state)
1954                 tmp = backup_state;
1955         else
1956                 tmp = alloc_session_state();
1957         backup_state = active_state;
1958         active_state = tmp;
1959 }
1960
1961 /*
1962  * Swap in the old state when resuming a connecion.
1963  */
1964 void
1965 packet_restore_state(void)
1966 {
1967         struct session_state *tmp;
1968         void *buf;
1969         u_int len;
1970
1971         tmp = backup_state;
1972         backup_state = active_state;
1973         active_state = tmp;
1974         active_state->connection_in = backup_state->connection_in;
1975         backup_state->connection_in = -1;
1976         active_state->connection_out = backup_state->connection_out;
1977         backup_state->connection_out = -1;
1978         len = buffer_len(&backup_state->input);
1979         if (len > 0) {
1980                 buf = buffer_ptr(&backup_state->input);
1981                 buffer_append(&active_state->input, buf, len);
1982                 buffer_clear(&backup_state->input);
1983                 add_recv_bytes(len);
1984         }
1985 }
1986
1987 #ifdef  NONE_CIPHER_ENABLED
1988 int
1989 packet_get_authentication_state(void)
1990 {
1991         return (active_state->after_authentication);
1992 }
1993 #endif