packet.c

   1 /* $OpenBSD: packet.c,v 1.161 2009/05/25 06:48:01 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_string(const void *buf, u_int len)
 600 {
 601         buffer_put_string(&active_state->outgoing_packet, buf, len);
 602 }
 603
 604 void
 605 packet_put_cstring(const char *str)
 606 {
 607         buffer_put_cstring(&active_state->outgoing_packet, str);
 608 }
 609
 610 void
 611 packet_put_raw(const void *buf, u_int len)
 612 {
 613         buffer_append(&active_state->outgoing_packet, buf, len);
 614 }
 615
 616 void
 617 packet_put_bignum(BIGNUM * value)
 618 {
 619         buffer_put_bignum(&active_state->outgoing_packet, value);
 620 }
 621
 622 void
 623 packet_put_bignum2(BIGNUM * value)
 624 {
 625         buffer_put_bignum2(&active_state->outgoing_packet, value);
 626 }
 627
 628 /*
 629  * Finalizes and sends the packet.  If the encryption key has been set,
 630  * encrypts the packet before sending.
 631  */
 632
 633 static void
 634 packet_send1(void)
 635 {
 636         u_char buf[8], *cp;
 637         int i, padding, len;
 638         u_int checksum;
 639         u_int32_t rnd = 0;
 640
 641         /*
 642          * If using packet compression, compress the payload of the outgoing
 643          * packet.
 644          */
 645         if (active_state->packet_compression) {
 646                 buffer_clear(&active_state->compression_buffer);
 647                 /* Skip padding. */
 648                 buffer_consume(&active_state->outgoing_packet, 8);
 649                 /* padding */
 650                 buffer_append(&active_state->compression_buffer,
 651                     "\0\0\0\0\0\0\0\0", 8);
 652                 buffer_compress(&active_state->outgoing_packet,
 653                     &active_state->compression_buffer);
 654                 buffer_clear(&active_state->outgoing_packet);
 655                 buffer_append(&active_state->outgoing_packet,
 656                     buffer_ptr(&active_state->compression_buffer),
 657                     buffer_len(&active_state->compression_buffer));
 658         }
 659         /* Compute packet length without padding (add checksum, remove padding). */
 660         len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
 661
 662         /* Insert padding. Initialized to zero in packet_start1() */
 663         padding = 8 - len % 8;
 664         if (!active_state->send_context.plaintext) {
 665                 cp = buffer_ptr(&active_state->outgoing_packet);
 666                 for (i = 0; i < padding; i++) {
 667                         if (i % 4 == 0)
 668                                 rnd = arc4random();
 669                         cp[7 - i] = rnd & 0xff;
 670                         rnd >>= 8;
 671                 }
 672         }
 673         buffer_consume(&active_state->outgoing_packet, 8 - padding);
 674
 675         /* Add check bytes. */
 676         checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
 677             buffer_len(&active_state->outgoing_packet));
 678         put_u32(buf, checksum);
 679         buffer_append(&active_state->outgoing_packet, buf, 4);
 680
 681 #ifdef PACKET_DEBUG
 682         fprintf(stderr, "packet_send plain: ");
 683         buffer_dump(&active_state->outgoing_packet);
 684 #endif
 685
 686         /* Append to output. */
 687         put_u32(buf, len);
 688         buffer_append(&active_state->output, buf, 4);
 689         cp = buffer_append_space(&active_state->output,
 690             buffer_len(&active_state->outgoing_packet));
 691         cipher_crypt(&active_state->send_context, cp,
 692             buffer_ptr(&active_state->outgoing_packet),
 693             buffer_len(&active_state->outgoing_packet));
 694
 695 #ifdef PACKET_DEBUG
 696         fprintf(stderr, "encrypted: ");
 697         buffer_dump(&active_state->output);
 698 #endif
 699         active_state->p_send.packets++;
 700         active_state->p_send.bytes += len +
 701             buffer_len(&active_state->outgoing_packet);
 702         buffer_clear(&active_state->outgoing_packet);
 703
 704         /*
 705          * Note that the packet is now only buffered in output.  It won't be
 706          * actually sent until packet_write_wait or packet_write_poll is
 707          * called.
 708          */
 709 }
 710
 711 void
 712 set_newkeys(int mode)
 713 {
 714         Enc *enc;
 715         Mac *mac;
 716         Comp *comp;
 717         CipherContext *cc;
 718         u_int64_t *max_blocks;
 719         int crypt_type;
 720
 721         debug2("set_newkeys: mode %d", mode);
 722
 723         if (mode == MODE_OUT) {
 724                 cc = &active_state->send_context;
 725                 crypt_type = CIPHER_ENCRYPT;
 726                 active_state->p_send.packets = active_state->p_send.blocks = 0;
 727                 max_blocks = &active_state->max_blocks_out;
 728         } else {
 729                 cc = &active_state->receive_context;
 730                 crypt_type = CIPHER_DECRYPT;
 731                 active_state->p_read.packets = active_state->p_read.blocks = 0;
 732                 max_blocks = &active_state->max_blocks_in;
 733         }
 734         if (active_state->newkeys[mode] != NULL) {
 735                 debug("set_newkeys: rekeying");
 736                 cipher_cleanup(cc);
 737                 enc  = &active_state->newkeys[mode]->enc;
 738                 mac  = &active_state->newkeys[mode]->mac;
 739                 comp = &active_state->newkeys[mode]->comp;
 740                 mac_clear(mac);
 741                 xfree(enc->name);
 742                 xfree(enc->iv);
 743                 xfree(enc->key);
 744                 xfree(mac->name);
 745                 xfree(mac->key);
 746                 xfree(comp->name);
 747                 xfree(active_state->newkeys[mode]);
 748         }
 749         active_state->newkeys[mode] = kex_get_newkeys(mode);
 750         if (active_state->newkeys[mode] == NULL)
 751                 fatal("newkeys: no keys for mode %d", mode);
 752         enc  = &active_state->newkeys[mode]->enc;
 753         mac  = &active_state->newkeys[mode]->mac;
 754         comp = &active_state->newkeys[mode]->comp;
 755         if (mac_init(mac) == 0)
 756                 mac->enabled = 1;
 757         DBG(debug("cipher_init_context: %d", mode));
 758         cipher_init(cc, enc->cipher, enc->key, enc->key_len,
 759             enc->iv, enc->block_size, crypt_type);
 760         /* Deleting the keys does not gain extra security */
 761         /* memset(enc->iv,  0, enc->block_size);
 762            memset(enc->key, 0, enc->key_len);
 763            memset(mac->key, 0, mac->key_len); */
 764         if ((comp->type == COMP_ZLIB ||
 765             (comp->type == COMP_DELAYED &&
 766              active_state->after_authentication)) && comp->enabled == 0) {
 767                 packet_init_compression();
 768                 if (mode == MODE_OUT)
 769                         buffer_compress_init_send(6);
 770                 else
 771                         buffer_compress_init_recv();
 772                 comp->enabled = 1;
 773         }
 774         /*
 775          * The 2^(blocksize*2) limit is too expensive for 3DES,
 776          * blowfish, etc, so enforce a 1GB limit for small blocksizes.
 777          */
 778         if (enc->block_size >= 16)
 779                 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
 780         else
 781                 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
 782         if (active_state->rekey_limit)
 783                 *max_blocks = MIN(*max_blocks,
 784                     active_state->rekey_limit / enc->block_size);
 785 }
 786
 787 /*
 788  * Delayed compression for SSH2 is enabled after authentication:
 789  * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
 790  * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
 791  */
 792 static void
 793 packet_enable_delayed_compress(void)
 794 {
 795         Comp *comp = NULL;
 796         int mode;
 797
 798         /*
 799          * Remember that we are past the authentication step, so rekeying
 800          * with COMP_DELAYED will turn on compression immediately.
 801          */
 802         active_state->after_authentication = 1;
 803         for (mode = 0; mode < MODE_MAX; mode++) {
 804                 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
 805                 if (active_state->newkeys[mode] == NULL)
 806                         continue;
 807                 comp = &active_state->newkeys[mode]->comp;
 808                 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
 809                         packet_init_compression();
 810                         if (mode == MODE_OUT)
 811                                 buffer_compress_init_send(6);
 812                         else
 813                                 buffer_compress_init_recv();
 814                         comp->enabled = 1;
 815                 }
 816         }
 817 }
 818
 819 /*
 820  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
 821  */
 822 static void
 823 packet_send2_wrapped(void)
 824 {
 825         u_char type, *cp, *macbuf = NULL;
 826         u_char padlen, pad;
 827         u_int packet_length = 0;
 828         u_int i, len;
 829         u_int32_t rnd = 0;
 830         Enc *enc   = NULL;
 831         Mac *mac   = NULL;
 832         Comp *comp = NULL;
 833         int block_size;
 834
 835         if (active_state->newkeys[MODE_OUT] != NULL) {
 836                 enc  = &active_state->newkeys[MODE_OUT]->enc;
 837                 mac  = &active_state->newkeys[MODE_OUT]->mac;
 838                 comp = &active_state->newkeys[MODE_OUT]->comp;
 839         }
 840         block_size = enc ? enc->block_size : 8;
 841
 842         cp = buffer_ptr(&active_state->outgoing_packet);
 843         type = cp[5];
 844
 845 #ifdef PACKET_DEBUG
 846         fprintf(stderr, "plain:     ");
 847         buffer_dump(&active_state->outgoing_packet);
 848 #endif
 849
 850         if (comp && comp->enabled) {
 851                 len = buffer_len(&active_state->outgoing_packet);
 852                 /* skip header, compress only payload */
 853                 buffer_consume(&active_state->outgoing_packet, 5);
 854                 buffer_clear(&active_state->compression_buffer);
 855                 buffer_compress(&active_state->outgoing_packet,
 856                     &active_state->compression_buffer);
 857                 buffer_clear(&active_state->outgoing_packet);
 858                 buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
 859                 buffer_append(&active_state->outgoing_packet,
 860                     buffer_ptr(&active_state->compression_buffer),
 861                     buffer_len(&active_state->compression_buffer));
 862                 DBG(debug("compression: raw %d compressed %d", len,
 863                     buffer_len(&active_state->outgoing_packet)));
 864         }
 865
 866         /* sizeof (packet_len + pad_len + payload) */
 867         len = buffer_len(&active_state->outgoing_packet);
 868
 869         /*
 870          * calc size of padding, alloc space, get random data,
 871          * minimum padding is 4 bytes
 872          */
 873         padlen = block_size - (len % block_size);
 874         if (padlen < 4)
 875                 padlen += block_size;
 876         if (active_state->extra_pad) {
 877                 /* will wrap if extra_pad+padlen > 255 */
 878                 active_state->extra_pad =
 879                     roundup(active_state->extra_pad, block_size);
 880                 pad = active_state->extra_pad -
 881                     ((len + padlen) % active_state->extra_pad);
 882                 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
 883                     pad, len, padlen, active_state->extra_pad);
 884                 padlen += pad;
 885                 active_state->extra_pad = 0;
 886         }
 887         cp = buffer_append_space(&active_state->outgoing_packet, padlen);
 888         if (enc && !active_state->send_context.plaintext) {
 889                 /* random padding */
 890                 for (i = 0; i < padlen; i++) {
 891                         if (i % 4 == 0)
 892                                 rnd = arc4random();
 893                         cp[i] = rnd & 0xff;
 894                         rnd >>= 8;
 895                 }
 896         } else {
 897                 /* clear padding */
 898                 memset(cp, 0, padlen);
 899         }
 900         /* packet_length includes payload, padding and padding length field */
 901         packet_length = buffer_len(&active_state->outgoing_packet) - 4;
 902         cp = buffer_ptr(&active_state->outgoing_packet);
 903         put_u32(cp, packet_length);
 904         cp[4] = padlen;
 905         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
 906
 907         /* compute MAC over seqnr and packet(length fields, payload, padding) */
 908         if (mac && mac->enabled) {
 909                 macbuf = mac_compute(mac, active_state->p_send.seqnr,
 910                     buffer_ptr(&active_state->outgoing_packet),
 911                     buffer_len(&active_state->outgoing_packet));
 912                 DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
 913         }
 914         /* encrypt packet and append to output buffer. */
 915         cp = buffer_append_space(&active_state->output,
 916             buffer_len(&active_state->outgoing_packet));
 917         cipher_crypt(&active_state->send_context, cp,
 918             buffer_ptr(&active_state->outgoing_packet),
 919             buffer_len(&active_state->outgoing_packet));
 920         /* append unencrypted MAC */
 921         if (mac && mac->enabled)
 922                 buffer_append(&active_state->output, macbuf, mac->mac_len);
 923 #ifdef PACKET_DEBUG
 924         fprintf(stderr, "encrypted: ");
 925         buffer_dump(&active_state->output);
 926 #endif
 927         /* increment sequence number for outgoing packets */
 928         if (++active_state->p_send.seqnr == 0)
 929                 logit("outgoing seqnr wraps around");
 930         if (++active_state->p_send.packets == 0)
 931                 if (!(datafellows & SSH_BUG_NOREKEY))
 932                         fatal("XXX too many packets with same key");
 933         active_state->p_send.blocks += (packet_length + 4) / block_size;
 934         active_state->p_send.bytes += packet_length + 4;
 935         buffer_clear(&active_state->outgoing_packet);
 936
 937         if (type == SSH2_MSG_NEWKEYS)
 938                 set_newkeys(MODE_OUT);
 939         else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
 940                 packet_enable_delayed_compress();
 941 }
 942
 943 static void
 944 packet_send2(void)
 945 {
 946         static int rekeying = 0;
 947         struct packet *p;
 948         u_char type, *cp;
 949
 950         cp = buffer_ptr(&active_state->outgoing_packet);
 951         type = cp[5];
 952
 953         /* during rekeying we can only send key exchange messages */
 954         if (rekeying) {
 955                 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
 956                     (type <= SSH2_MSG_TRANSPORT_MAX))) {
 957                         debug("enqueue packet: %u", type);
 958                         p = xmalloc(sizeof(*p));
 959                         p->type = type;
 960                         memcpy(&p->payload, &active_state->outgoing_packet,
 961                             sizeof(Buffer));
 962                         buffer_init(&active_state->outgoing_packet);
 963                         TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
 964                         return;
 965                 }
 966         }
 967
 968         /* rekeying starts with sending KEXINIT */
 969         if (type == SSH2_MSG_KEXINIT)
 970                 rekeying = 1;
 971
 972         packet_send2_wrapped();
 973
 974         /* after a NEWKEYS message we can send the complete queue */
 975         if (type == SSH2_MSG_NEWKEYS) {
 976                 rekeying = 0;
 977                 while ((p = TAILQ_FIRST(&active_state->outgoing))) {
 978                         type = p->type;
 979                         debug("dequeue packet: %u", type);
 980                         buffer_free(&active_state->outgoing_packet);
 981                         memcpy(&active_state->outgoing_packet, &p->payload,
 982                             sizeof(Buffer));
 983                         TAILQ_REMOVE(&active_state->outgoing, p, next);
 984                         xfree(p);
 985                         packet_send2_wrapped();
 986                 }
 987         }
 988 }
 989
 990 void
 991 packet_send(void)
 992 {
 993         if (compat20)
 994                 packet_send2();
 995         else
 996                 packet_send1();
 997         DBG(debug("packet_send done"));
 998 }
 999
1000 /*
1001  * Waits until a packet has been received, and returns its type.  Note that
1002  * no other data is processed until this returns, so this function should not
1003  * be used during the interactive session.
1004  */
1005
1006 int
1007 packet_read_seqnr(u_int32_t *seqnr_p)
1008 {
1009         int type, len, ret, ms_remain;
1010         fd_set *setp;
1011         char buf[8192];
1012         struct timeval timeout, start, *timeoutp = NULL;
1013
1014         DBG(debug("packet_read()"));
1015
1016         setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
1017             NFDBITS), sizeof(fd_mask));
1018
1019         /* Since we are blocking, ensure that all written packets have been sent. */
1020         packet_write_wait();
1021
1022         /* Stay in the loop until we have received a complete packet. */
1023         for (;;) {
1024                 /* Try to read a packet from the buffer. */
1025                 type = packet_read_poll_seqnr(seqnr_p);
1026                 if (!compat20 && (
1027                     type == SSH_SMSG_SUCCESS
1028                     || type == SSH_SMSG_FAILURE
1029                     || type == SSH_CMSG_EOF
1030                     || type == SSH_CMSG_EXIT_CONFIRMATION))
1031                         packet_check_eom();
1032                 /* If we got a packet, return it. */
1033                 if (type != SSH_MSG_NONE) {
1034                         xfree(setp);
1035                         return type;
1036                 }
1037                 /*
1038                  * Otherwise, wait for some data to arrive, add it to the
1039                  * buffer, and try again.
1040                  */
1041                 memset(setp, 0, howmany(active_state->connection_in + 1,
1042                     NFDBITS) * sizeof(fd_mask));
1043                 FD_SET(active_state->connection_in, setp);
1044
1045                 if (active_state->packet_timeout_ms > 0) {
1046                         ms_remain = active_state->packet_timeout_ms;
1047                         timeoutp = &timeout;
1048                 }
1049                 /* Wait for some data to arrive. */
1050                 for (;;) {
1051                         if (active_state->packet_timeout_ms != -1) {
1052                                 ms_to_timeval(&timeout, ms_remain);
1053                                 gettimeofday(&start, NULL);
1054                         }
1055                         if ((ret = select(active_state->connection_in + 1, setp,
1056                             NULL, NULL, timeoutp)) >= 0)
1057                                 break;
1058                         if (errno != EAGAIN && errno != EINTR &&
1059                             errno != EWOULDBLOCK)
1060                                 break;
1061                         if (active_state->packet_timeout_ms == -1)
1062                                 continue;
1063                         ms_subtract_diff(&start, &ms_remain);
1064                         if (ms_remain <= 0) {
1065                                 ret = 0;
1066                                 break;
1067                         }
1068                 }
1069                 if (ret == 0) {
1070                         logit("Connection to %.200s timed out while "
1071                             "waiting to read", get_remote_ipaddr());
1072                         cleanup_exit(255);
1073                 }
1074                 /* Read data from the socket. */
1075                 len = read(active_state->connection_in, buf, sizeof(buf));
1076                 if (len == 0) {
1077                         logit("Connection closed by %.200s", get_remote_ipaddr());
1078                         cleanup_exit(255);
1079                 }
1080                 if (len < 0)
1081                         fatal("Read from socket failed: %.100s", strerror(errno));
1082                 /* Append it to the buffer. */
1083                 packet_process_incoming(buf, len);
1084         }
1085         /* NOTREACHED */
1086 }
1087
1088 int
1089 packet_read(void)
1090 {
1091         return packet_read_seqnr(NULL);
1092 }
1093
1094 /*
1095  * Waits until a packet has been received, verifies that its type matches
1096  * that given, and gives a fatal error and exits if there is a mismatch.
1097  */
1098
1099 void
1100 packet_read_expect(int expected_type)
1101 {
1102         int type;
1103
1104         type = packet_read();
1105         if (type != expected_type)
1106                 packet_disconnect("Protocol error: expected packet type %d, got %d",
1107                     expected_type, type);
1108 }
1109
1110 /* Checks if a full packet is available in the data received so far via
1111  * packet_process_incoming.  If so, reads the packet; otherwise returns
1112  * SSH_MSG_NONE.  This does not wait for data from the connection.
1113  *
1114  * SSH_MSG_DISCONNECT is handled specially here.  Also,
1115  * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1116  * to higher levels.
1117  */
1118
1119 static int
1120 packet_read_poll1(void)
1121 {
1122         u_int len, padded_len;
1123         u_char *cp, type;
1124         u_int checksum, stored_checksum;
1125
1126         /* Check if input size is less than minimum packet size. */
1127         if (buffer_len(&active_state->input) < 4 + 8)
1128                 return SSH_MSG_NONE;
1129         /* Get length of incoming packet. */
1130         cp = buffer_ptr(&active_state->input);
1131         len = get_u32(cp);
1132         if (len < 1 + 2 + 2 || len > 256 * 1024)
1133                 packet_disconnect("Bad packet length %u.", len);
1134         padded_len = (len + 8) & ~7;
1135
1136         /* Check if the packet has been entirely received. */
1137         if (buffer_len(&active_state->input) < 4 + padded_len)
1138                 return SSH_MSG_NONE;
1139
1140         /* The entire packet is in buffer. */
1141
1142         /* Consume packet length. */
1143         buffer_consume(&active_state->input, 4);
1144
1145         /*
1146          * Cryptographic attack detector for ssh
1147          * (C)1998 CORE-SDI, Buenos Aires Argentina
1148          * Ariel Futoransky(futo@core-sdi.com)
1149          */
1150         if (!active_state->receive_context.plaintext) {
1151                 switch (detect_attack(buffer_ptr(&active_state->input),
1152                     padded_len)) {
1153                 case DEATTACK_DETECTED:
1154                         packet_disconnect("crc32 compensation attack: "
1155                             "network attack detected");
1156                 case DEATTACK_DOS_DETECTED:
1157                         packet_disconnect("deattack denial of "
1158                             "service detected");
1159                 }
1160         }
1161
1162         /* Decrypt data to incoming_packet. */
1163         buffer_clear(&active_state->incoming_packet);
1164         cp = buffer_append_space(&active_state->incoming_packet, padded_len);
1165         cipher_crypt(&active_state->receive_context, cp,
1166             buffer_ptr(&active_state->input), padded_len);
1167
1168         buffer_consume(&active_state->input, padded_len);
1169
1170 #ifdef PACKET_DEBUG
1171         fprintf(stderr, "read_poll plain: ");
1172         buffer_dump(&active_state->incoming_packet);
1173 #endif
1174
1175         /* Compute packet checksum. */
1176         checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
1177             buffer_len(&active_state->incoming_packet) - 4);
1178
1179         /* Skip padding. */
1180         buffer_consume(&active_state->incoming_packet, 8 - len % 8);
1181
1182         /* Test check bytes. */
1183         if (len != buffer_len(&active_state->incoming_packet))
1184                 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1185                     len, buffer_len(&active_state->incoming_packet));
1186
1187         cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
1188         stored_checksum = get_u32(cp);
1189         if (checksum != stored_checksum)
1190                 packet_disconnect("Corrupted check bytes on input.");
1191         buffer_consume_end(&active_state->incoming_packet, 4);
1192
1193         if (active_state->packet_compression) {
1194                 buffer_clear(&active_state->compression_buffer);
1195                 buffer_uncompress(&active_state->incoming_packet,
1196                     &active_state->compression_buffer);
1197                 buffer_clear(&active_state->incoming_packet);
1198                 buffer_append(&active_state->incoming_packet,
1199                     buffer_ptr(&active_state->compression_buffer),
1200                     buffer_len(&active_state->compression_buffer));
1201         }
1202         active_state->p_read.packets++;
1203         active_state->p_read.bytes += padded_len + 4;
1204         type = buffer_get_char(&active_state->incoming_packet);
1205         if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1206                 packet_disconnect("Invalid ssh1 packet type: %d", type);
1207         return type;
1208 }
1209
1210 static int
1211 packet_read_poll2(u_int32_t *seqnr_p)
1212 {
1213         u_int padlen, need;
1214         u_char *macbuf, *cp, type;
1215         u_int maclen, block_size;
1216         Enc *enc   = NULL;
1217         Mac *mac   = NULL;
1218         Comp *comp = NULL;
1219
1220         if (active_state->packet_discard)
1221                 return SSH_MSG_NONE;
1222
1223         if (active_state->newkeys[MODE_IN] != NULL) {
1224                 enc  = &active_state->newkeys[MODE_IN]->enc;
1225                 mac  = &active_state->newkeys[MODE_IN]->mac;
1226                 comp = &active_state->newkeys[MODE_IN]->comp;
1227         }
1228         maclen = mac && mac->enabled ? mac->mac_len : 0;
1229         block_size = enc ? enc->block_size : 8;
1230
1231         if (active_state->packlen == 0) {
1232                 /*
1233                  * check if input size is less than the cipher block size,
1234                  * decrypt first block and extract length of incoming packet
1235                  */
1236                 if (buffer_len(&active_state->input) < block_size)
1237                         return SSH_MSG_NONE;
1238                 buffer_clear(&active_state->incoming_packet);
1239                 cp = buffer_append_space(&active_state->incoming_packet,
1240                     block_size);
1241                 cipher_crypt(&active_state->receive_context, cp,
1242                     buffer_ptr(&active_state->input), block_size);
1243                 cp = buffer_ptr(&active_state->incoming_packet);
1244                 active_state->packlen = get_u32(cp);
1245                 if (active_state->packlen < 1 + 4 ||
1246                     active_state->packlen > PACKET_MAX_SIZE) {
1247 #ifdef PACKET_DEBUG
1248                         buffer_dump(&active_state->incoming_packet);
1249 #endif
1250                         logit("Bad packet length %u.", active_state->packlen);
1251                         packet_start_discard(enc, mac, active_state->packlen,
1252                             PACKET_MAX_SIZE);
1253                         return SSH_MSG_NONE;
1254                 }
1255                 DBG(debug("input: packet len %u", active_state->packlen+4));
1256                 buffer_consume(&active_state->input, block_size);
1257         }
1258         /* we have a partial packet of block_size bytes */
1259         need = 4 + active_state->packlen - block_size;
1260         DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1261             need, maclen));
1262         if (need % block_size != 0) {
1263                 logit("padding error: need %d block %d mod %d",
1264                     need, block_size, need % block_size);
1265                 packet_start_discard(enc, mac, active_state->packlen,
1266                     PACKET_MAX_SIZE - block_size);
1267                 return SSH_MSG_NONE;
1268         }
1269         /*
1270          * check if the entire packet has been received and
1271          * decrypt into incoming_packet
1272          */
1273         if (buffer_len(&active_state->input) < need + maclen)
1274                 return SSH_MSG_NONE;
1275 #ifdef PACKET_DEBUG
1276         fprintf(stderr, "read_poll enc/full: ");
1277         buffer_dump(&active_state->input);
1278 #endif
1279         cp = buffer_append_space(&active_state->incoming_packet, need);
1280         cipher_crypt(&active_state->receive_context, cp,
1281             buffer_ptr(&active_state->input), need);
1282         buffer_consume(&active_state->input, need);
1283         /*
1284          * compute MAC over seqnr and packet,
1285          * increment sequence number for incoming packet
1286          */
1287         if (mac && mac->enabled) {
1288                 macbuf = mac_compute(mac, active_state->p_read.seqnr,
1289                     buffer_ptr(&active_state->incoming_packet),
1290                     buffer_len(&active_state->incoming_packet));
1291                 if (memcmp(macbuf, buffer_ptr(&active_state->input),
1292                     mac->mac_len) != 0) {
1293                         logit("Corrupted MAC on input.");
1294                         if (need > PACKET_MAX_SIZE)
1295                                 fatal("internal error need %d", need);
1296                         packet_start_discard(enc, mac, active_state->packlen,
1297                             PACKET_MAX_SIZE - need);
1298                         return SSH_MSG_NONE;
1299                 }
1300
1301                 DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
1302                 buffer_consume(&active_state->input, mac->mac_len);
1303         }
1304         /* XXX now it's safe to use fatal/packet_disconnect */
1305         if (seqnr_p != NULL)
1306                 *seqnr_p = active_state->p_read.seqnr;
1307         if (++active_state->p_read.seqnr == 0)
1308                 logit("incoming seqnr wraps around");
1309         if (++active_state->p_read.packets == 0)
1310                 if (!(datafellows & SSH_BUG_NOREKEY))
1311                         fatal("XXX too many packets with same key");
1312         active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
1313         active_state->p_read.bytes += active_state->packlen + 4;
1314
1315         /* get padlen */
1316         cp = buffer_ptr(&active_state->incoming_packet);
1317         padlen = cp[4];
1318         DBG(debug("input: padlen %d", padlen));
1319         if (padlen < 4)
1320                 packet_disconnect("Corrupted padlen %d on input.", padlen);
1321
1322         /* skip packet size + padlen, discard padding */
1323         buffer_consume(&active_state->incoming_packet, 4 + 1);
1324         buffer_consume_end(&active_state->incoming_packet, padlen);
1325
1326         DBG(debug("input: len before de-compress %d",
1327             buffer_len(&active_state->incoming_packet)));
1328         if (comp && comp->enabled) {
1329                 buffer_clear(&active_state->compression_buffer);
1330                 buffer_uncompress(&active_state->incoming_packet,
1331                     &active_state->compression_buffer);
1332                 buffer_clear(&active_state->incoming_packet);
1333                 buffer_append(&active_state->incoming_packet,
1334                     buffer_ptr(&active_state->compression_buffer),
1335                     buffer_len(&active_state->compression_buffer));
1336                 DBG(debug("input: len after de-compress %d",
1337                     buffer_len(&active_state->incoming_packet)));
1338         }
1339         /*
1340          * get packet type, implies consume.
1341          * return length of payload (without type field)
1342          */
1343         type = buffer_get_char(&active_state->incoming_packet);
1344         if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1345                 packet_disconnect("Invalid ssh2 packet type: %d", type);
1346         if (type == SSH2_MSG_NEWKEYS)
1347                 set_newkeys(MODE_IN);
1348         else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
1349             !active_state->server_side)
1350                 packet_enable_delayed_compress();
1351 #ifdef PACKET_DEBUG
1352         fprintf(stderr, "read/plain[%d]:\r\n", type);
1353         buffer_dump(&active_state->incoming_packet);
1354 #endif
1355         /* reset for next packet */
1356         active_state->packlen = 0;
1357         return type;
1358 }
1359
1360 int
1361 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1362 {
1363         u_int reason, seqnr;
1364         u_char type;
1365         char *msg;
1366
1367         for (;;) {
1368                 if (compat20) {
1369                         type = packet_read_poll2(seqnr_p);
1370                         if (type) {
1371                                 active_state->keep_alive_timeouts = 0;
1372                                 DBG(debug("received packet type %d", type));
1373                         }
1374                         switch (type) {
1375                         case SSH2_MSG_IGNORE:
1376                                 debug3("Received SSH2_MSG_IGNORE");
1377                                 break;
1378                         case SSH2_MSG_DEBUG:
1379                                 packet_get_char();
1380                                 msg = packet_get_string(NULL);
1381                                 debug("Remote: %.900s", msg);
1382                                 xfree(msg);
1383                                 msg = packet_get_string(NULL);
1384                                 xfree(msg);
1385                                 break;
1386                         case SSH2_MSG_DISCONNECT:
1387                                 reason = packet_get_int();
1388                                 msg = packet_get_string(NULL);
1389                                 logit("Received disconnect from %s: %u: %.400s",
1390                                     get_remote_ipaddr(), reason, msg);
1391                                 xfree(msg);
1392                                 cleanup_exit(255);
1393                                 break;
1394                         case SSH2_MSG_UNIMPLEMENTED:
1395                                 seqnr = packet_get_int();
1396                                 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1397                                     seqnr);
1398                                 break;
1399                         default:
1400                                 return type;
1401                         }
1402                 } else {
1403                         type = packet_read_poll1();
1404                         switch (type) {
1405                         case SSH_MSG_IGNORE:
1406                                 break;
1407                         case SSH_MSG_DEBUG:
1408                                 msg = packet_get_string(NULL);
1409                                 debug("Remote: %.900s", msg);
1410                                 xfree(msg);
1411                                 break;
1412                         case SSH_MSG_DISCONNECT:
1413                                 msg = packet_get_string(NULL);
1414                                 logit("Received disconnect from %s: %.400s",
1415                                     get_remote_ipaddr(), msg);
1416                                 cleanup_exit(255);
1417                                 break;
1418                         default:
1419                                 if (type)
1420                                         DBG(debug("received packet type %d", type));
1421                                 return type;
1422                         }
1423                 }
1424         }
1425 }
1426
1427 int
1428 packet_read_poll(void)
1429 {
1430         return packet_read_poll_seqnr(NULL);
1431 }
1432
1433 /*
1434  * Buffers the given amount of input characters.  This is intended to be used
1435  * together with packet_read_poll.
1436  */
1437
1438 void
1439 packet_process_incoming(const char *buf, u_int len)
1440 {
1441         if (active_state->packet_discard) {
1442                 active_state->keep_alive_timeouts = 0; /* ?? */
1443                 if (len >= active_state->packet_discard)
1444                         packet_stop_discard();
1445                 active_state->packet_discard -= len;
1446                 return;
1447         }
1448         buffer_append(&active_state->input, buf, len);
1449 }
1450
1451 /* Returns a character from the packet. */
1452
1453 u_int
1454 packet_get_char(void)
1455 {
1456         char ch;
1457
1458         buffer_get(&active_state->incoming_packet, &ch, 1);
1459         return (u_char) ch;
1460 }
1461
1462 /* Returns an integer from the packet data. */
1463
1464 u_int
1465 packet_get_int(void)
1466 {
1467         return buffer_get_int(&active_state->incoming_packet);
1468 }
1469
1470 /*
1471  * Returns an arbitrary precision integer from the packet data.  The integer
1472  * must have been initialized before this call.
1473  */
1474
1475 void
1476 packet_get_bignum(BIGNUM * value)
1477 {
1478         buffer_get_bignum(&active_state->incoming_packet, value);
1479 }
1480
1481 void
1482 packet_get_bignum2(BIGNUM * value)
1483 {
1484         buffer_get_bignum2(&active_state->incoming_packet, value);
1485 }
1486
1487 void *
1488 packet_get_raw(u_int *length_ptr)
1489 {
1490         u_int bytes = buffer_len(&active_state->incoming_packet);
1491
1492         if (length_ptr != NULL)
1493                 *length_ptr = bytes;
1494         return buffer_ptr(&active_state->incoming_packet);
1495 }
1496
1497 int
1498 packet_remaining(void)
1499 {
1500         return buffer_len(&active_state->incoming_packet);
1501 }
1502
1503 /*
1504  * Returns a string from the packet data.  The string is allocated using
1505  * xmalloc; it is the responsibility of the calling program to free it when
1506  * no longer needed.  The length_ptr argument may be NULL, or point to an
1507  * integer into which the length of the string is stored.
1508  */
1509
1510 void *
1511 packet_get_string(u_int *length_ptr)
1512 {
1513         return buffer_get_string(&active_state->incoming_packet, length_ptr);
1514 }
1515
1516 void *
1517 packet_get_string_ptr(u_int *length_ptr)
1518 {
1519         return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
1520 }
1521
1522 /*
1523  * Sends a diagnostic message from the server to the client.  This message
1524  * can be sent at any time (but not while constructing another message). The
1525  * message is printed immediately, but only if the client is being executed
1526  * in verbose mode.  These messages are primarily intended to ease debugging
1527  * authentication problems.   The length of the formatted message must not
1528  * exceed 1024 bytes.  This will automatically call packet_write_wait.
1529  */
1530
1531 void
1532 packet_send_debug(const char *fmt,...)
1533 {
1534         char buf[1024];
1535         va_list args;
1536
1537         if (compat20 && (datafellows & SSH_BUG_DEBUG))
1538                 return;
1539
1540         va_start(args, fmt);
1541         vsnprintf(buf, sizeof(buf), fmt, args);
1542         va_end(args);
1543
1544         if (compat20) {
1545                 packet_start(SSH2_MSG_DEBUG);
1546                 packet_put_char(0);     /* bool: always display */
1547                 packet_put_cstring(buf);
1548                 packet_put_cstring("");
1549         } else {
1550                 packet_start(SSH_MSG_DEBUG);
1551                 packet_put_cstring(buf);
1552         }
1553         packet_send();
1554         packet_write_wait();
1555 }
1556
1557 /*
1558  * Logs the error plus constructs and sends a disconnect packet, closes the
1559  * connection, and exits.  This function never returns. The error message
1560  * should not contain a newline.  The length of the formatted message must
1561  * not exceed 1024 bytes.
1562  */
1563
1564 void
1565 packet_disconnect(const char *fmt,...)
1566 {
1567         char buf[1024];
1568         va_list args;
1569         static int disconnecting = 0;
1570
1571         if (disconnecting)      /* Guard against recursive invocations. */
1572                 fatal("packet_disconnect called recursively.");
1573         disconnecting = 1;
1574
1575         /*
1576          * Format the message.  Note that the caller must make sure the
1577          * message is of limited size.
1578          */
1579         va_start(args, fmt);
1580         vsnprintf(buf, sizeof(buf), fmt, args);
1581         va_end(args);
1582
1583         /* Display the error locally */
1584         logit("Disconnecting: %.100s", buf);
1585
1586         /* Send the disconnect message to the other side, and wait for it to get sent. */
1587         if (compat20) {
1588                 packet_start(SSH2_MSG_DISCONNECT);
1589                 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1590                 packet_put_cstring(buf);
1591                 packet_put_cstring("");
1592         } else {
1593                 packet_start(SSH_MSG_DISCONNECT);
1594                 packet_put_cstring(buf);
1595         }
1596         packet_send();
1597         packet_write_wait();
1598
1599         /* Stop listening for connections. */
1600         channel_close_all();
1601
1602         /* Close the connection. */
1603         packet_close();
1604         cleanup_exit(255);
1605 }
1606
1607 /* Checks if there is any buffered output, and tries to write some of the output. */
1608
1609 void
1610 packet_write_poll(void)
1611 {
1612         int len = buffer_len(&active_state->output);
1613
1614         if (len > 0) {
1615                 len = write(active_state->connection_out,
1616                     buffer_ptr(&active_state->output), len);
1617                 if (len == -1) {
1618                         if (errno == EINTR || errno == EAGAIN ||
1619                             errno == EWOULDBLOCK)
1620                                 return;
1621                         fatal("Write failed: %.100s", strerror(errno));
1622                 }
1623                 if (len == 0)
1624                         fatal("Write connection closed");
1625                 buffer_consume(&active_state->output, len);
1626         }
1627 }
1628
1629
1630 /*
1631  * Calls packet_write_poll repeatedly until all pending output data has been
1632  * written.
1633  */
1634
1635 void
1636 packet_write_wait(void)
1637 {
1638         fd_set *setp;
1639         int ret, ms_remain;
1640         struct timeval start, timeout, *timeoutp = NULL;
1641
1642         setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
1643             NFDBITS), sizeof(fd_mask));
1644         packet_write_poll();
1645         while (packet_have_data_to_write()) {
1646                 memset(setp, 0, howmany(active_state->connection_out + 1,
1647                     NFDBITS) * sizeof(fd_mask));
1648                 FD_SET(active_state->connection_out, setp);
1649
1650                 if (active_state->packet_timeout_ms > 0) {
1651                         ms_remain = active_state->packet_timeout_ms;
1652                         timeoutp = &timeout;
1653                 }
1654                 for (;;) {
1655                         if (active_state->packet_timeout_ms != -1) {
1656                                 ms_to_timeval(&timeout, ms_remain);
1657                                 gettimeofday(&start, NULL);
1658                         }
1659                         if ((ret = select(active_state->connection_out + 1,
1660                             NULL, setp, NULL, timeoutp)) >= 0)
1661                                 break;
1662                         if (errno != EAGAIN && errno != EINTR &&
1663                             errno != EWOULDBLOCK)
1664                                 break;
1665                         if (active_state->packet_timeout_ms == -1)
1666                                 continue;
1667                         ms_subtract_diff(&start, &ms_remain);
1668                         if (ms_remain <= 0) {
1669                                 ret = 0;
1670                                 break;
1671                         }
1672                 }
1673                 if (ret == 0) {
1674                         logit("Connection to %.200s timed out while "
1675                             "waiting to write", get_remote_ipaddr());
1676                         cleanup_exit(255);
1677                 }
1678                 packet_write_poll();
1679         }
1680         xfree(setp);
1681 }
1682
1683 /* Returns true if there is buffered data to write to the connection. */
1684
1685 int
1686 packet_have_data_to_write(void)
1687 {
1688         return buffer_len(&active_state->output) != 0;
1689 }
1690
1691 /* Returns true if there is not too much data to write to the connection. */
1692
1693 int
1694 packet_not_very_much_data_to_write(void)
1695 {
1696         if (active_state->interactive_mode)
1697                 return buffer_len(&active_state->output) < 16384;
1698         else
1699                 return buffer_len(&active_state->output) < 128 * 1024;
1700 }
1701
1702
1703 static void
1704 packet_set_tos(int interactive)
1705 {
1706 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1707         int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1708
1709         if (!packet_connection_is_on_socket() ||
1710             !packet_connection_is_ipv4())
1711                 return;
1712         if (setsockopt(active_state->connection_in, IPPROTO_IP, IP_TOS, &tos,
1713             sizeof(tos)) < 0)
1714                 error("setsockopt IP_TOS %d: %.100s:",
1715                     tos, strerror(errno));
1716 #endif
1717 }
1718
1719 /* Informs that the current session is interactive.  Sets IP flags for that. */
1720
1721 void
1722 packet_set_interactive(int interactive)
1723 {
1724         static int called = 0;
1725
1726         if (called)
1727                 return;
1728         called = 1;
1729
1730         /* Record that we are in interactive mode. */
1731         active_state->interactive_mode = interactive;
1732
1733         /* Only set socket options if using a socket.  */
1734         if (!packet_connection_is_on_socket())
1735                 return;
1736         set_nodelay(active_state->connection_in);
1737         packet_set_tos(interactive);
1738 }
1739
1740 /* Returns true if the current connection is interactive. */
1741
1742 int
1743 packet_is_interactive(void)
1744 {
1745         return active_state->interactive_mode;
1746 }
1747
1748 int
1749 packet_set_maxsize(u_int s)
1750 {
1751         static int called = 0;
1752
1753         if (called) {
1754                 logit("packet_set_maxsize: called twice: old %d new %d",
1755                     active_state->max_packet_size, s);
1756                 return -1;
1757         }
1758         if (s < 4 * 1024 || s > 1024 * 1024) {
1759                 logit("packet_set_maxsize: bad size %d", s);
1760                 return -1;
1761         }
1762         called = 1;
1763         debug("packet_set_maxsize: setting to %d", s);
1764         active_state->max_packet_size = s;
1765         return s;
1766 }
1767
1768 int
1769 packet_inc_alive_timeouts(void)
1770 {
1771         return ++active_state->keep_alive_timeouts;
1772 }
1773
1774 void
1775 packet_set_alive_timeouts(int ka)
1776 {
1777         active_state->keep_alive_timeouts = ka;
1778 }
1779
1780 u_int
1781 packet_get_maxsize(void)
1782 {
1783         return active_state->max_packet_size;
1784 }
1785
1786 /* roundup current message to pad bytes */
1787 void
1788 packet_add_padding(u_char pad)
1789 {
1790         active_state->extra_pad = pad;
1791 }
1792
1793 /*
1794  * 9.2.  Ignored Data Message
1795  *
1796  *   byte      SSH_MSG_IGNORE
1797  *   string    data
1798  *
1799  * All implementations MUST understand (and ignore) this message at any
1800  * time (after receiving the protocol version). No implementation is
1801  * required to send them. This message can be used as an additional
1802  * protection measure against advanced traffic analysis techniques.
1803  */
1804 void
1805 packet_send_ignore(int nbytes)
1806 {
1807         u_int32_t rnd = 0;
1808         int i;
1809
1810         packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1811         packet_put_int(nbytes);
1812         for (i = 0; i < nbytes; i++) {
1813                 if (i % 4 == 0)
1814                         rnd = arc4random();
1815                 packet_put_char((u_char)rnd & 0xff);
1816                 rnd >>= 8;
1817         }
1818 }
1819
1820 #define MAX_PACKETS     (1U<<31)
1821 int
1822 packet_need_rekeying(void)
1823 {
1824         if (datafellows & SSH_BUG_NOREKEY)
1825                 return 0;
1826         return
1827             (active_state->p_send.packets > MAX_PACKETS) ||
1828             (active_state->p_read.packets > MAX_PACKETS) ||
1829             (active_state->max_blocks_out &&
1830                 (active_state->p_send.blocks > active_state->max_blocks_out)) ||
1831             (active_state->max_blocks_in &&
1832                 (active_state->p_read.blocks > active_state->max_blocks_in));
1833 }
1834
1835 void
1836 packet_set_rekey_limit(u_int32_t bytes)
1837 {
1838         active_state->rekey_limit = bytes;
1839 }
1840
1841 void
1842 packet_set_server(void)
1843 {
1844         active_state->server_side = 1;
1845 }
1846
1847 void
1848 packet_set_authenticated(void)
1849 {
1850         active_state->after_authentication = 1;
1851 }
1852
1853 void *
1854 packet_get_input(void)
1855 {
1856         return (void *)&active_state->input;
1857 }
1858
1859 void *
1860 packet_get_output(void)
1861 {
1862         return (void *)&active_state->output;
1863 }
1864
1865 void *
1866 packet_get_newkeys(int mode)
1867 {
1868         return (void *)active_state->newkeys[mode];
1869 }