Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
| 2 | |
| 3 | packet.c |
| 4 | |
| 5 | Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 6 | |
| 7 | Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 8 | All rights reserved |
| 9 | |
| 10 | Created: Sat Mar 18 02:40:40 1995 ylo |
| 11 | |
| 12 | This file contains code implementing the packet protocol and communication |
| 13 | with the other side. This same code is used both on client and server side. |
| 14 | |
| 15 | */ |
| 16 | |
| 17 | #include "includes.h" |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 18 | RCSID("$Id: packet.c,v 1.3 1999/11/16 02:37:16 damien Exp $"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 19 | |
| 20 | #include "xmalloc.h" |
| 21 | #include "buffer.h" |
| 22 | #include "packet.h" |
| 23 | #include "bufaux.h" |
| 24 | #include "ssh.h" |
| 25 | #include "crc32.h" |
| 26 | #include "cipher.h" |
| 27 | #include "getput.h" |
| 28 | |
| 29 | #include "compress.h" |
| 30 | #include "deattack.h" |
| 31 | |
| 32 | /* This variable contains the file descriptors used for communicating with |
| 33 | the other side. connection_in is used for reading; connection_out |
| 34 | for writing. These can be the same descriptor, in which case it is |
| 35 | assumed to be a socket. */ |
| 36 | static int connection_in = -1; |
| 37 | static int connection_out = -1; |
| 38 | |
| 39 | /* Cipher type. This value is only used to determine whether to pad the |
| 40 | packets with zeroes or random data. */ |
| 41 | static int cipher_type = SSH_CIPHER_NONE; |
| 42 | |
| 43 | /* Protocol flags for the remote side. */ |
| 44 | static unsigned int remote_protocol_flags = 0; |
| 45 | |
| 46 | /* Encryption context for receiving data. This is only used for decryption. */ |
| 47 | static CipherContext receive_context; |
| 48 | /* Encryption coontext for sending data. This is only used for encryption. */ |
| 49 | static CipherContext send_context; |
| 50 | |
| 51 | /* Buffer for raw input data from the socket. */ |
| 52 | static Buffer input; |
| 53 | |
| 54 | /* Buffer for raw output data going to the socket. */ |
| 55 | static Buffer output; |
| 56 | |
| 57 | /* Buffer for the partial outgoing packet being constructed. */ |
| 58 | static Buffer outgoing_packet; |
| 59 | |
| 60 | /* Buffer for the incoming packet currently being processed. */ |
| 61 | static Buffer incoming_packet; |
| 62 | |
| 63 | /* Scratch buffer for packet compression/decompression. */ |
| 64 | static Buffer compression_buffer; |
| 65 | |
| 66 | /* Flag indicating whether packet compression/decompression is enabled. */ |
| 67 | static int packet_compression = 0; |
| 68 | |
| 69 | /* Flag indicating whether this module has been initialized. */ |
| 70 | static int initialized = 0; |
| 71 | |
| 72 | /* Set to true if the connection is interactive. */ |
| 73 | static int interactive_mode = 0; |
| 74 | |
| 75 | /* Sets the descriptors used for communication. Disables encryption until |
| 76 | packet_set_encryption_key is called. */ |
| 77 | |
| 78 | void |
| 79 | packet_set_connection(int fd_in, int fd_out) |
| 80 | { |
| 81 | connection_in = fd_in; |
| 82 | connection_out = fd_out; |
| 83 | cipher_type = SSH_CIPHER_NONE; |
| 84 | cipher_set_key(&send_context, SSH_CIPHER_NONE, (unsigned char *)"", 0, 1); |
| 85 | cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *)"", 0, 0); |
| 86 | if (!initialized) |
| 87 | { |
| 88 | initialized = 1; |
| 89 | buffer_init(&input); |
| 90 | buffer_init(&output); |
| 91 | buffer_init(&outgoing_packet); |
| 92 | buffer_init(&incoming_packet); |
| 93 | } |
| 94 | |
| 95 | /* Kludge: arrange the close function to be called from fatal(). */ |
| 96 | fatal_add_cleanup((void (*)(void *))packet_close, NULL); |
| 97 | } |
| 98 | |
| 99 | /* Sets the connection into non-blocking mode. */ |
| 100 | |
| 101 | void |
| 102 | packet_set_nonblocking() |
| 103 | { |
| 104 | /* Set the socket into non-blocking mode. */ |
| 105 | if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) |
| 106 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); |
| 107 | |
| 108 | if (connection_out != connection_in) |
| 109 | { |
| 110 | if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) |
| 111 | error("fcntl O_NONBLOCK: %.100s", strerror(errno)); |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | /* Returns the socket used for reading. */ |
| 116 | |
| 117 | int |
| 118 | packet_get_connection_in() |
| 119 | { |
| 120 | return connection_in; |
| 121 | } |
| 122 | |
| 123 | /* Returns the descriptor used for writing. */ |
| 124 | |
| 125 | int |
| 126 | packet_get_connection_out() |
| 127 | { |
| 128 | return connection_out; |
| 129 | } |
| 130 | |
| 131 | /* Closes the connection and clears and frees internal data structures. */ |
| 132 | |
| 133 | void |
| 134 | packet_close() |
| 135 | { |
| 136 | if (!initialized) |
| 137 | return; |
| 138 | initialized = 0; |
| 139 | if (connection_in == connection_out) |
| 140 | { |
| 141 | shutdown(connection_out, SHUT_RDWR); |
| 142 | close(connection_out); |
| 143 | } |
| 144 | else |
| 145 | { |
| 146 | close(connection_in); |
| 147 | close(connection_out); |
| 148 | } |
| 149 | buffer_free(&input); |
| 150 | buffer_free(&output); |
| 151 | buffer_free(&outgoing_packet); |
| 152 | buffer_free(&incoming_packet); |
| 153 | if (packet_compression) |
| 154 | { |
| 155 | buffer_free(&compression_buffer); |
| 156 | buffer_compress_uninit(); |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | /* Sets remote side protocol flags. */ |
| 161 | |
| 162 | void |
| 163 | packet_set_protocol_flags(unsigned int protocol_flags) |
| 164 | { |
| 165 | remote_protocol_flags = protocol_flags; |
| 166 | channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0); |
| 167 | } |
| 168 | |
| 169 | /* Returns the remote protocol flags set earlier by the above function. */ |
| 170 | |
| 171 | unsigned int |
| 172 | packet_get_protocol_flags() |
| 173 | { |
| 174 | return remote_protocol_flags; |
| 175 | } |
| 176 | |
| 177 | /* Starts packet compression from the next packet on in both directions. |
| 178 | Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ |
| 179 | |
| 180 | void |
| 181 | packet_start_compression(int level) |
| 182 | { |
| 183 | if (packet_compression) |
| 184 | fatal("Compression already enabled."); |
| 185 | packet_compression = 1; |
| 186 | buffer_init(&compression_buffer); |
| 187 | buffer_compress_init(level); |
| 188 | } |
| 189 | |
| 190 | /* Encrypts the given number of bytes, copying from src to dest. |
| 191 | bytes is known to be a multiple of 8. */ |
| 192 | |
| 193 | void |
| 194 | packet_encrypt(CipherContext *cc, void *dest, void *src, |
| 195 | unsigned int bytes) |
| 196 | { |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 197 | cipher_encrypt(cc, dest, src, bytes); |
| 198 | } |
| 199 | |
| 200 | /* Decrypts the given number of bytes, copying from src to dest. |
| 201 | bytes is known to be a multiple of 8. */ |
| 202 | |
| 203 | void |
| 204 | packet_decrypt(CipherContext *cc, void *dest, void *src, |
| 205 | unsigned int bytes) |
| 206 | { |
| 207 | int i; |
| 208 | |
Damien Miller | fd7c911 | 1999-11-08 16:15:55 +1100 | [diff] [blame] | 209 | if ((bytes % 8) != 0) |
| 210 | fatal("packet_decrypt: bad ciphertext length %d", bytes); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 211 | |
| 212 | /* |
| 213 | Cryptographic attack detector for ssh - Modifications for packet.c |
| 214 | (C)1998 CORE-SDI, Buenos Aires Argentina |
| 215 | Ariel Futoransky(futo@core-sdi.com) |
| 216 | */ |
| 217 | switch (cc->type) |
| 218 | { |
| 219 | case SSH_CIPHER_NONE: |
| 220 | i = DEATTACK_OK; |
| 221 | break; |
| 222 | default: |
| 223 | i = detect_attack(src, bytes, NULL); |
| 224 | break; |
| 225 | } |
| 226 | |
| 227 | if (i == DEATTACK_DETECTED) |
| 228 | packet_disconnect("crc32 compensation attack: network attack detected"); |
| 229 | |
| 230 | cipher_decrypt(cc, dest, src, bytes); |
| 231 | } |
| 232 | |
| 233 | /* Causes any further packets to be encrypted using the given key. The same |
| 234 | key is used for both sending and reception. However, both directions |
| 235 | are encrypted independently of each other. */ |
| 236 | |
| 237 | void |
| 238 | packet_set_encryption_key(const unsigned char *key, unsigned int keylen, |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 239 | int cipher) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 240 | { |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 241 | /* All other ciphers use the same key in both directions for now. */ |
| 242 | cipher_set_key(&receive_context, cipher, key, keylen, 0); |
| 243 | cipher_set_key(&send_context, cipher, key, keylen, 1); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 244 | } |
| 245 | |
| 246 | /* Starts constructing a packet to send. */ |
| 247 | |
| 248 | void |
| 249 | packet_start(int type) |
| 250 | { |
| 251 | char buf[9]; |
| 252 | |
| 253 | buffer_clear(&outgoing_packet); |
| 254 | memset(buf, 0, 8); |
| 255 | buf[8] = type; |
| 256 | buffer_append(&outgoing_packet, buf, 9); |
| 257 | } |
| 258 | |
| 259 | /* Appends a character to the packet data. */ |
| 260 | |
| 261 | void |
| 262 | packet_put_char(int value) |
| 263 | { |
| 264 | char ch = value; |
| 265 | buffer_append(&outgoing_packet, &ch, 1); |
| 266 | } |
| 267 | |
| 268 | /* Appends an integer to the packet data. */ |
| 269 | |
| 270 | void |
| 271 | packet_put_int(unsigned int value) |
| 272 | { |
| 273 | buffer_put_int(&outgoing_packet, value); |
| 274 | } |
| 275 | |
| 276 | /* Appends a string to packet data. */ |
| 277 | |
| 278 | void |
| 279 | packet_put_string(const char *buf, unsigned int len) |
| 280 | { |
| 281 | buffer_put_string(&outgoing_packet, buf, len); |
| 282 | } |
| 283 | |
| 284 | /* Appends an arbitrary precision integer to packet data. */ |
| 285 | |
| 286 | void |
| 287 | packet_put_bignum(BIGNUM *value) |
| 288 | { |
| 289 | buffer_put_bignum(&outgoing_packet, value); |
| 290 | } |
| 291 | |
| 292 | /* Finalizes and sends the packet. If the encryption key has been set, |
| 293 | encrypts the packet before sending. */ |
| 294 | |
| 295 | void |
| 296 | packet_send() |
| 297 | { |
| 298 | char buf[8], *cp; |
| 299 | int i, padding, len; |
| 300 | unsigned int checksum; |
| 301 | u_int32_t rand = 0; |
| 302 | |
| 303 | /* If using packet compression, compress the payload of the outgoing |
| 304 | packet. */ |
| 305 | if (packet_compression) |
| 306 | { |
| 307 | buffer_clear(&compression_buffer); |
| 308 | buffer_consume(&outgoing_packet, 8); /* Skip padding. */ |
| 309 | buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); /* padding */ |
| 310 | buffer_compress(&outgoing_packet, &compression_buffer); |
| 311 | buffer_clear(&outgoing_packet); |
| 312 | buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), |
| 313 | buffer_len(&compression_buffer)); |
| 314 | } |
| 315 | |
| 316 | /* Compute packet length without padding (add checksum, remove padding). */ |
| 317 | len = buffer_len(&outgoing_packet) + 4 - 8; |
| 318 | |
| 319 | /* Insert padding. */ |
| 320 | padding = 8 - len % 8; |
| 321 | if (cipher_type != SSH_CIPHER_NONE) |
| 322 | { |
| 323 | cp = buffer_ptr(&outgoing_packet); |
| 324 | for (i = 0; i < padding; i++) { |
| 325 | if (i % 4 == 0) |
| 326 | rand = arc4random(); |
| 327 | cp[7 - i] = rand & 0xff; |
| 328 | rand >>= 8; |
| 329 | } |
| 330 | } |
| 331 | buffer_consume(&outgoing_packet, 8 - padding); |
| 332 | |
| 333 | /* Add check bytes. */ |
| 334 | checksum = crc32((unsigned char *)buffer_ptr(&outgoing_packet), |
| 335 | buffer_len(&outgoing_packet)); |
| 336 | PUT_32BIT(buf, checksum); |
| 337 | buffer_append(&outgoing_packet, buf, 4); |
| 338 | |
| 339 | #ifdef PACKET_DEBUG |
| 340 | fprintf(stderr, "packet_send plain: "); |
| 341 | buffer_dump(&outgoing_packet); |
| 342 | #endif |
| 343 | |
| 344 | /* Append to output. */ |
| 345 | PUT_32BIT(buf, len); |
| 346 | buffer_append(&output, buf, 4); |
| 347 | buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); |
| 348 | packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), |
| 349 | buffer_len(&outgoing_packet)); |
| 350 | |
| 351 | #ifdef PACKET_DEBUG |
| 352 | fprintf(stderr, "encrypted: "); buffer_dump(&output); |
| 353 | #endif |
| 354 | |
| 355 | buffer_clear(&outgoing_packet); |
| 356 | |
| 357 | /* Note that the packet is now only buffered in output. It won\'t be |
| 358 | actually sent until packet_write_wait or packet_write_poll is called. */ |
| 359 | } |
| 360 | |
| 361 | /* Waits until a packet has been received, and returns its type. Note that |
| 362 | no other data is processed until this returns, so this function should |
| 363 | not be used during the interactive session. */ |
| 364 | |
| 365 | int |
| 366 | packet_read(int *payload_len_ptr) |
| 367 | { |
| 368 | int type, len; |
| 369 | fd_set set; |
| 370 | char buf[8192]; |
| 371 | |
| 372 | /* Since we are blocking, ensure that all written packets have been sent. */ |
| 373 | packet_write_wait(); |
| 374 | |
| 375 | /* Stay in the loop until we have received a complete packet. */ |
| 376 | for (;;) |
| 377 | { |
| 378 | /* Try to read a packet from the buffer. */ |
| 379 | type = packet_read_poll(payload_len_ptr); |
| 380 | if (type == SSH_SMSG_SUCCESS |
| 381 | || type == SSH_SMSG_FAILURE |
| 382 | || type == SSH_CMSG_EOF |
| 383 | || type == SSH_CMSG_EXIT_CONFIRMATION) |
| 384 | packet_integrity_check(*payload_len_ptr, 0, type); |
| 385 | /* If we got a packet, return it. */ |
| 386 | if (type != SSH_MSG_NONE) |
| 387 | return type; |
| 388 | /* Otherwise, wait for some data to arrive, add it to the buffer, |
| 389 | and try again. */ |
| 390 | FD_ZERO(&set); |
| 391 | FD_SET(connection_in, &set); |
| 392 | /* Wait for some data to arrive. */ |
| 393 | select(connection_in + 1, &set, NULL, NULL, NULL); |
| 394 | /* Read data from the socket. */ |
| 395 | len = read(connection_in, buf, sizeof(buf)); |
| 396 | if (len == 0) |
| 397 | fatal("Connection closed by remote host."); |
| 398 | if (len < 0) |
| 399 | fatal("Read from socket failed: %.100s", strerror(errno)); |
| 400 | /* Append it to the buffer. */ |
| 401 | packet_process_incoming(buf, len); |
| 402 | } |
| 403 | /*NOTREACHED*/ |
| 404 | } |
| 405 | |
| 406 | /* Waits until a packet has been received, verifies that its type matches |
| 407 | that given, and gives a fatal error and exits if there is a mismatch. */ |
| 408 | |
| 409 | void |
| 410 | packet_read_expect(int *payload_len_ptr, int expected_type) |
| 411 | { |
| 412 | int type; |
| 413 | |
| 414 | type = packet_read(payload_len_ptr); |
| 415 | if (type != expected_type) |
| 416 | packet_disconnect("Protocol error: expected packet type %d, got %d", |
| 417 | expected_type, type); |
| 418 | } |
| 419 | |
| 420 | /* Checks if a full packet is available in the data received so far via |
| 421 | packet_process_incoming. If so, reads the packet; otherwise returns |
| 422 | SSH_MSG_NONE. This does not wait for data from the connection. |
| 423 | |
| 424 | SSH_MSG_DISCONNECT is handled specially here. Also, |
| 425 | SSH_MSG_IGNORE messages are skipped by this function and are never returned |
| 426 | to higher levels. |
| 427 | |
| 428 | The returned payload_len does include space consumed by: |
| 429 | Packet length |
| 430 | Padding |
| 431 | Packet type |
| 432 | Check bytes |
| 433 | |
| 434 | |
| 435 | */ |
| 436 | |
| 437 | int |
| 438 | packet_read_poll(int *payload_len_ptr) |
| 439 | { |
| 440 | unsigned int len, padded_len; |
| 441 | unsigned char *ucp; |
| 442 | char buf[8], *cp; |
| 443 | unsigned int checksum, stored_checksum; |
| 444 | |
| 445 | restart: |
| 446 | |
| 447 | /* Check if input size is less than minimum packet size. */ |
| 448 | if (buffer_len(&input) < 4 + 8) |
| 449 | return SSH_MSG_NONE; |
| 450 | /* Get length of incoming packet. */ |
| 451 | ucp = (unsigned char *)buffer_ptr(&input); |
| 452 | len = GET_32BIT(ucp); |
| 453 | if (len < 1 + 2 + 2 || len > 256*1024) |
| 454 | packet_disconnect("Bad packet length %d.", len); |
| 455 | padded_len = (len + 8) & ~7; |
| 456 | |
| 457 | /* Check if the packet has been entirely received. */ |
| 458 | if (buffer_len(&input) < 4 + padded_len) |
| 459 | return SSH_MSG_NONE; |
| 460 | |
| 461 | /* The entire packet is in buffer. */ |
| 462 | |
| 463 | /* Consume packet length. */ |
| 464 | buffer_consume(&input, 4); |
| 465 | |
| 466 | /* Copy data to incoming_packet. */ |
| 467 | buffer_clear(&incoming_packet); |
| 468 | buffer_append_space(&incoming_packet, &cp, padded_len); |
| 469 | packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); |
| 470 | buffer_consume(&input, padded_len); |
| 471 | |
| 472 | #ifdef PACKET_DEBUG |
| 473 | fprintf(stderr, "read_poll plain: "); buffer_dump(&incoming_packet); |
| 474 | #endif |
| 475 | |
| 476 | /* Compute packet checksum. */ |
| 477 | checksum = crc32((unsigned char *)buffer_ptr(&incoming_packet), |
| 478 | buffer_len(&incoming_packet) - 4); |
| 479 | |
| 480 | /* Skip padding. */ |
| 481 | buffer_consume(&incoming_packet, 8 - len % 8); |
| 482 | |
| 483 | /* Test check bytes. */ |
Damien Miller | fd7c911 | 1999-11-08 16:15:55 +1100 | [diff] [blame] | 484 | |
| 485 | if (len != buffer_len(&incoming_packet)) |
| 486 | packet_disconnect("packet_read_poll: len %d != buffer_len %d.", |
| 487 | len, buffer_len(&incoming_packet)); |
| 488 | |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 489 | ucp = (unsigned char *)buffer_ptr(&incoming_packet) + len - 4; |
| 490 | stored_checksum = GET_32BIT(ucp); |
| 491 | if (checksum != stored_checksum) |
| 492 | packet_disconnect("Corrupted check bytes on input."); |
| 493 | buffer_consume_end(&incoming_packet, 4); |
| 494 | |
| 495 | /* If using packet compression, decompress the packet. */ |
| 496 | if (packet_compression) |
| 497 | { |
| 498 | buffer_clear(&compression_buffer); |
| 499 | buffer_uncompress(&incoming_packet, &compression_buffer); |
| 500 | buffer_clear(&incoming_packet); |
| 501 | buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), |
| 502 | buffer_len(&compression_buffer)); |
| 503 | } |
| 504 | |
| 505 | /* Get packet type. */ |
| 506 | buffer_get(&incoming_packet, &buf[0], 1); |
| 507 | |
| 508 | /* Return length of payload (without type field). */ |
| 509 | *payload_len_ptr = buffer_len(&incoming_packet); |
| 510 | |
| 511 | /* Handle disconnect message. */ |
| 512 | if ((unsigned char)buf[0] == SSH_MSG_DISCONNECT) |
| 513 | fatal("%.900s", packet_get_string(NULL)); |
| 514 | |
| 515 | /* Ignore ignore messages. */ |
| 516 | if ((unsigned char)buf[0] == SSH_MSG_IGNORE) |
| 517 | goto restart; |
| 518 | |
| 519 | /* Send debug messages as debugging output. */ |
| 520 | if ((unsigned char)buf[0] == SSH_MSG_DEBUG) |
| 521 | { |
| 522 | debug("Remote: %.900s", packet_get_string(NULL)); |
| 523 | goto restart; |
| 524 | } |
| 525 | |
| 526 | /* Return type. */ |
| 527 | return (unsigned char)buf[0]; |
| 528 | } |
| 529 | |
| 530 | /* Buffers the given amount of input characters. This is intended to be |
| 531 | used together with packet_read_poll. */ |
| 532 | |
| 533 | void |
| 534 | packet_process_incoming(const char *buf, unsigned int len) |
| 535 | { |
| 536 | buffer_append(&input, buf, len); |
| 537 | } |
| 538 | |
| 539 | /* Returns a character from the packet. */ |
| 540 | |
| 541 | unsigned int |
| 542 | packet_get_char() |
| 543 | { |
| 544 | char ch; |
| 545 | buffer_get(&incoming_packet, &ch, 1); |
| 546 | return (unsigned char)ch; |
| 547 | } |
| 548 | |
| 549 | /* Returns an integer from the packet data. */ |
| 550 | |
| 551 | unsigned int |
| 552 | packet_get_int() |
| 553 | { |
| 554 | return buffer_get_int(&incoming_packet); |
| 555 | } |
| 556 | |
| 557 | /* Returns an arbitrary precision integer from the packet data. The integer |
| 558 | must have been initialized before this call. */ |
| 559 | |
| 560 | void |
| 561 | packet_get_bignum(BIGNUM *value, int *length_ptr) |
| 562 | { |
| 563 | *length_ptr = buffer_get_bignum(&incoming_packet, value); |
| 564 | } |
| 565 | |
| 566 | /* Returns a string from the packet data. The string is allocated using |
| 567 | xmalloc; it is the responsibility of the calling program to free it when |
| 568 | no longer needed. The length_ptr argument may be NULL, or point to an |
| 569 | integer into which the length of the string is stored. */ |
| 570 | |
| 571 | char |
| 572 | *packet_get_string(unsigned int *length_ptr) |
| 573 | { |
| 574 | return buffer_get_string(&incoming_packet, length_ptr); |
| 575 | } |
| 576 | |
| 577 | /* Sends a diagnostic message from the server to the client. This message |
| 578 | can be sent at any time (but not while constructing another message). |
| 579 | The message is printed immediately, but only if the client is being |
| 580 | executed in verbose mode. These messages are primarily intended to |
| 581 | ease debugging authentication problems. The length of the formatted |
| 582 | message must not exceed 1024 bytes. This will automatically call |
| 583 | packet_write_wait. */ |
| 584 | |
| 585 | void |
| 586 | packet_send_debug(const char *fmt, ...) |
| 587 | { |
| 588 | char buf[1024]; |
| 589 | va_list args; |
| 590 | |
| 591 | va_start(args, fmt); |
| 592 | vsnprintf(buf, sizeof(buf), fmt, args); |
| 593 | va_end(args); |
| 594 | |
| 595 | packet_start(SSH_MSG_DEBUG); |
| 596 | packet_put_string(buf, strlen(buf)); |
| 597 | packet_send(); |
| 598 | packet_write_wait(); |
| 599 | } |
| 600 | |
| 601 | /* Logs the error plus constructs and sends a disconnect |
| 602 | packet, closes the connection, and exits. This function never returns. |
| 603 | The error message should not contain a newline. The length of the |
| 604 | formatted message must not exceed 1024 bytes. */ |
| 605 | |
| 606 | void |
| 607 | packet_disconnect(const char *fmt, ...) |
| 608 | { |
| 609 | char buf[1024]; |
| 610 | va_list args; |
| 611 | static int disconnecting = 0; |
| 612 | if (disconnecting) /* Guard against recursive invocations. */ |
| 613 | fatal("packet_disconnect called recursively."); |
| 614 | disconnecting = 1; |
| 615 | |
| 616 | /* Format the message. Note that the caller must make sure the message |
| 617 | is of limited size. */ |
| 618 | va_start(args, fmt); |
| 619 | vsnprintf(buf, sizeof(buf), fmt, args); |
| 620 | va_end(args); |
| 621 | |
| 622 | /* Send the disconnect message to the other side, and wait for it to get |
| 623 | sent. */ |
| 624 | packet_start(SSH_MSG_DISCONNECT); |
| 625 | packet_put_string(buf, strlen(buf)); |
| 626 | packet_send(); |
| 627 | packet_write_wait(); |
| 628 | |
| 629 | /* Stop listening for connections. */ |
| 630 | channel_stop_listening(); |
| 631 | |
| 632 | /* Close the connection. */ |
| 633 | packet_close(); |
| 634 | |
| 635 | /* Display the error locally and exit. */ |
| 636 | fatal("Local: %.100s", buf); |
| 637 | } |
| 638 | |
| 639 | /* Checks if there is any buffered output, and tries to write some of the |
| 640 | output. */ |
| 641 | |
| 642 | void |
| 643 | packet_write_poll() |
| 644 | { |
| 645 | int len = buffer_len(&output); |
| 646 | if (len > 0) |
| 647 | { |
| 648 | len = write(connection_out, buffer_ptr(&output), len); |
| 649 | if (len <= 0) { |
| 650 | if (errno == EAGAIN) |
| 651 | return; |
| 652 | else |
| 653 | fatal("Write failed: %.100s", strerror(errno)); |
| 654 | } |
| 655 | buffer_consume(&output, len); |
| 656 | } |
| 657 | } |
| 658 | |
| 659 | /* Calls packet_write_poll repeatedly until all pending output data has |
| 660 | been written. */ |
| 661 | |
| 662 | void |
| 663 | packet_write_wait() |
| 664 | { |
| 665 | packet_write_poll(); |
| 666 | while (packet_have_data_to_write()) |
| 667 | { |
| 668 | fd_set set; |
| 669 | FD_ZERO(&set); |
| 670 | FD_SET(connection_out, &set); |
| 671 | select(connection_out + 1, NULL, &set, NULL, NULL); |
| 672 | packet_write_poll(); |
| 673 | } |
| 674 | } |
| 675 | |
| 676 | /* Returns true if there is buffered data to write to the connection. */ |
| 677 | |
| 678 | int |
| 679 | packet_have_data_to_write() |
| 680 | { |
| 681 | return buffer_len(&output) != 0; |
| 682 | } |
| 683 | |
| 684 | /* Returns true if there is not too much data to write to the connection. */ |
| 685 | |
| 686 | int |
| 687 | packet_not_very_much_data_to_write() |
| 688 | { |
| 689 | if (interactive_mode) |
| 690 | return buffer_len(&output) < 16384; |
| 691 | else |
| 692 | return buffer_len(&output) < 128*1024; |
| 693 | } |
| 694 | |
| 695 | /* Informs that the current session is interactive. Sets IP flags for that. */ |
| 696 | |
| 697 | void |
| 698 | packet_set_interactive(int interactive, int keepalives) |
| 699 | { |
| 700 | int on = 1; |
| 701 | |
| 702 | /* Record that we are in interactive mode. */ |
| 703 | interactive_mode = interactive; |
| 704 | |
| 705 | /* Only set socket options if using a socket (as indicated by the descriptors |
| 706 | being the same). */ |
| 707 | if (connection_in != connection_out) |
| 708 | return; |
| 709 | |
| 710 | if (keepalives) |
| 711 | { |
| 712 | /* Set keepalives if requested. */ |
| 713 | if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, |
| 714 | sizeof(on)) < 0) |
| 715 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); |
| 716 | } |
| 717 | |
| 718 | if (interactive) |
| 719 | { |
| 720 | /* Set IP options for an interactive connection. Use IPTOS_LOWDELAY |
| 721 | and TCP_NODELAY. */ |
| 722 | int lowdelay = IPTOS_LOWDELAY; |
| 723 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *)&lowdelay, |
| 724 | sizeof(lowdelay)) < 0) |
| 725 | error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno)); |
| 726 | if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *)&on, |
| 727 | sizeof(on)) < 0) |
| 728 | error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); |
| 729 | } |
| 730 | else |
| 731 | { |
| 732 | /* Set IP options for a non-interactive connection. Use |
| 733 | IPTOS_THROUGHPUT. */ |
| 734 | int throughput = IPTOS_THROUGHPUT; |
| 735 | if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *)&throughput, |
| 736 | sizeof(throughput)) < 0) |
| 737 | error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); |
| 738 | } |
| 739 | } |
| 740 | |
| 741 | /* Returns true if the current connection is interactive. */ |
| 742 | |
| 743 | int |
| 744 | packet_is_interactive() |
| 745 | { |
| 746 | return interactive_mode; |
| 747 | } |