2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This file contains code implementing the packet protocol and communication
6 * with the other side. This same code is used both on client and server side.
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
15 * SSH2 packet format added by Markus Friedl.
16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 RCSID("$OpenBSD: packet.c,v 1.115 2004/06/21 17:36:31 avsm Exp $");
42 #include "openbsd-compat/sys-queue.h"
74 * This variable contains the file descriptors used for communicating with
75 * the other side. connection_in is used for reading; connection_out for
76 * writing. These can be the same descriptor, in which case it is assumed to
79 static int connection_in = -1;
80 static int connection_out = -1;
82 /* Protocol flags for the remote side. */
83 static u_int remote_protocol_flags = 0;
85 /* Encryption context for receiving data. This is only used for decryption. */
86 static CipherContext receive_context;
88 /* Encryption context for sending data. This is only used for encryption. */
89 static CipherContext send_context;
91 /* Buffer for raw input data from the socket. */
94 /* Buffer for raw output data going to the socket. */
97 /* Buffer for the partial outgoing packet being constructed. */
98 static Buffer outgoing_packet;
100 /* Buffer for the incoming packet currently being processed. */
101 static Buffer incoming_packet;
103 /* Scratch buffer for packet compression/decompression. */
104 static Buffer compression_buffer;
105 static int compression_buffer_ready = 0;
107 /* Flag indicating whether packet compression/decompression is enabled. */
108 static int packet_compression = 0;
110 /* default maximum packet size */
111 u_int max_packet_size = 32768;
113 /* Flag indicating whether this module has been initialized. */
114 static int initialized = 0;
116 /* Set to true if the connection is interactive. */
117 static int interactive_mode = 0;
119 /* Session key information for Encryption and MAC */
120 Newkeys *newkeys[MODE_MAX];
121 static struct packet_state {
127 static u_int64_t max_blocks_in, max_blocks_out;
128 static u_int32_t rekey_limit;
130 /* Session key for protocol v1 */
131 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
132 static u_int ssh1_keylen;
134 /* roundup current message to extra_pad bytes */
135 static u_char extra_pad = 0;
138 TAILQ_ENTRY(packet) next;
142 TAILQ_HEAD(, packet) outgoing;
145 * Sets the descriptors used for communication. Disables encryption until
146 * packet_set_encryption_key is called.
149 packet_set_connection(int fd_in, int fd_out)
151 Cipher *none = cipher_by_name("none");
154 fatal("packet_set_connection: cannot load cipher 'none'");
155 connection_in = fd_in;
156 connection_out = fd_out;
157 cipher_init(&send_context, none, (const u_char *)"",
158 0, NULL, 0, CIPHER_ENCRYPT);
159 cipher_init(&receive_context, none, (const u_char *)"",
160 0, NULL, 0, CIPHER_DECRYPT);
161 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
165 buffer_init(&output);
166 buffer_init(&outgoing_packet);
167 buffer_init(&incoming_packet);
168 TAILQ_INIT(&outgoing);
172 /* Returns 1 if remote host is connected via socket, 0 if not. */
175 packet_connection_is_on_socket(void)
177 struct sockaddr_storage from, to;
178 socklen_t fromlen, tolen;
180 /* filedescriptors in and out are the same, so it's a socket */
181 if (connection_in == connection_out)
183 fromlen = sizeof(from);
184 memset(&from, 0, sizeof(from));
185 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
188 memset(&to, 0, sizeof(to));
189 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
191 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
193 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
199 * Exports an IV from the CipherContext required to export the key
200 * state back from the unprivileged child to the privileged parent
205 packet_get_keyiv(int mode, u_char *iv, u_int len)
209 if (mode == MODE_OUT)
212 cc = &receive_context;
214 cipher_get_keyiv(cc, iv, len);
218 packet_get_keycontext(int mode, u_char *dat)
222 if (mode == MODE_OUT)
225 cc = &receive_context;
227 return (cipher_get_keycontext(cc, dat));
231 packet_set_keycontext(int mode, u_char *dat)
235 if (mode == MODE_OUT)
238 cc = &receive_context;
240 cipher_set_keycontext(cc, dat);
244 packet_get_keyiv_len(int mode)
248 if (mode == MODE_OUT)
251 cc = &receive_context;
253 return (cipher_get_keyiv_len(cc));
256 packet_set_iv(int mode, u_char *dat)
260 if (mode == MODE_OUT)
263 cc = &receive_context;
265 cipher_set_keyiv(cc, dat);
268 packet_get_ssh1_cipher(void)
270 return (cipher_get_number(receive_context.cipher));
274 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets)
276 struct packet_state *state;
278 state = (mode == MODE_IN) ? &p_read : &p_send;
279 *seqnr = state->seqnr;
280 *blocks = state->blocks;
281 *packets = state->packets;
285 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets)
287 struct packet_state *state;
289 state = (mode == MODE_IN) ? &p_read : &p_send;
290 state->seqnr = seqnr;
291 state->blocks = blocks;
292 state->packets = packets;
295 /* returns 1 if connection is via ipv4 */
298 packet_connection_is_ipv4(void)
300 struct sockaddr_storage to;
301 socklen_t tolen = sizeof(to);
303 memset(&to, 0, sizeof(to));
304 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
306 if (to.ss_family == AF_INET)
309 if (to.ss_family == AF_INET6 &&
310 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
316 /* Sets the connection into non-blocking mode. */
319 packet_set_nonblocking(void)
321 /* Set the socket into non-blocking mode. */
322 set_nonblock(connection_in);
324 if (connection_out != connection_in)
325 set_nonblock(connection_out);
328 /* Returns the socket used for reading. */
331 packet_get_connection_in(void)
333 return connection_in;
336 /* Returns the descriptor used for writing. */
339 packet_get_connection_out(void)
341 return connection_out;
344 /* Closes the connection and clears and frees internal data structures. */
352 if (connection_in == connection_out) {
353 shutdown(connection_out, SHUT_RDWR);
354 close(connection_out);
356 close(connection_in);
357 close(connection_out);
360 buffer_free(&output);
361 buffer_free(&outgoing_packet);
362 buffer_free(&incoming_packet);
363 if (compression_buffer_ready) {
364 buffer_free(&compression_buffer);
365 buffer_compress_uninit();
367 cipher_cleanup(&send_context);
368 cipher_cleanup(&receive_context);
371 /* Sets remote side protocol flags. */
374 packet_set_protocol_flags(u_int protocol_flags)
376 remote_protocol_flags = protocol_flags;
379 /* Returns the remote protocol flags set earlier by the above function. */
382 packet_get_protocol_flags(void)
384 return remote_protocol_flags;
388 * Starts packet compression from the next packet on in both directions.
389 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
393 packet_init_compression(void)
395 if (compression_buffer_ready == 1)
397 compression_buffer_ready = 1;
398 buffer_init(&compression_buffer);
402 packet_start_compression(int level)
404 if (packet_compression && !compat20)
405 fatal("Compression already enabled.");
406 packet_compression = 1;
407 packet_init_compression();
408 buffer_compress_init_send(level);
409 buffer_compress_init_recv();
413 * Causes any further packets to be encrypted using the given key. The same
414 * key is used for both sending and reception. However, both directions are
415 * encrypted independently of each other.
419 packet_set_encryption_key(const u_char *key, u_int keylen,
422 Cipher *cipher = cipher_by_number(number);
425 fatal("packet_set_encryption_key: unknown cipher number %d", number);
427 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
428 if (keylen > SSH_SESSION_KEY_LENGTH)
429 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
430 memcpy(ssh1_key, key, keylen);
431 ssh1_keylen = keylen;
432 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
433 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
437 packet_get_encryption_key(u_char *key)
440 return (ssh1_keylen);
441 memcpy(key, ssh1_key, ssh1_keylen);
442 return (ssh1_keylen);
445 /* Start constructing a packet to send. */
447 packet_start(u_char type)
452 DBG(debug("packet_start[%d]", type));
453 len = compat20 ? 6 : 9;
454 memset(buf, 0, len - 1);
456 buffer_clear(&outgoing_packet);
457 buffer_append(&outgoing_packet, buf, len);
460 /* Append payload. */
462 packet_put_char(int value)
466 buffer_append(&outgoing_packet, &ch, 1);
469 packet_put_int(u_int value)
471 buffer_put_int(&outgoing_packet, value);
474 packet_put_string(const void *buf, u_int len)
476 buffer_put_string(&outgoing_packet, buf, len);
479 packet_put_cstring(const char *str)
481 buffer_put_cstring(&outgoing_packet, str);
484 packet_put_raw(const void *buf, u_int len)
486 buffer_append(&outgoing_packet, buf, len);
489 packet_put_bignum(BIGNUM * value)
491 buffer_put_bignum(&outgoing_packet, value);
494 packet_put_bignum2(BIGNUM * value)
496 buffer_put_bignum2(&outgoing_packet, value);
500 * Finalizes and sends the packet. If the encryption key has been set,
501 * encrypts the packet before sending.
513 * If using packet compression, compress the payload of the outgoing
516 if (packet_compression) {
517 buffer_clear(&compression_buffer);
519 buffer_consume(&outgoing_packet, 8);
521 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
522 buffer_compress(&outgoing_packet, &compression_buffer);
523 buffer_clear(&outgoing_packet);
524 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
525 buffer_len(&compression_buffer));
527 /* Compute packet length without padding (add checksum, remove padding). */
528 len = buffer_len(&outgoing_packet) + 4 - 8;
530 /* Insert padding. Initialized to zero in packet_start1() */
531 padding = 8 - len % 8;
532 if (!send_context.plaintext) {
533 cp = buffer_ptr(&outgoing_packet);
534 for (i = 0; i < padding; i++) {
537 cp[7 - i] = rnd & 0xff;
541 buffer_consume(&outgoing_packet, 8 - padding);
543 /* Add check bytes. */
544 checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
545 buffer_len(&outgoing_packet));
546 PUT_32BIT(buf, checksum);
547 buffer_append(&outgoing_packet, buf, 4);
550 fprintf(stderr, "packet_send plain: ");
551 buffer_dump(&outgoing_packet);
554 /* Append to output. */
556 buffer_append(&output, buf, 4);
557 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
558 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
559 buffer_len(&outgoing_packet));
562 fprintf(stderr, "encrypted: ");
563 buffer_dump(&output);
566 buffer_clear(&outgoing_packet);
569 * Note that the packet is now only buffered in output. It won\'t be
570 * actually sent until packet_write_wait or packet_write_poll is
576 set_newkeys(int mode)
582 u_int64_t *max_blocks;
585 debug2("set_newkeys: mode %d", mode);
587 if (mode == MODE_OUT) {
589 crypt_type = CIPHER_ENCRYPT;
590 p_send.packets = p_send.blocks = 0;
591 max_blocks = &max_blocks_out;
593 cc = &receive_context;
594 crypt_type = CIPHER_DECRYPT;
595 p_read.packets = p_read.blocks = 0;
596 max_blocks = &max_blocks_in;
598 if (newkeys[mode] != NULL) {
599 debug("set_newkeys: rekeying");
601 enc = &newkeys[mode]->enc;
602 mac = &newkeys[mode]->mac;
603 comp = &newkeys[mode]->comp;
604 memset(mac->key, 0, mac->key_len);
611 xfree(newkeys[mode]);
613 newkeys[mode] = kex_get_newkeys(mode);
614 if (newkeys[mode] == NULL)
615 fatal("newkeys: no keys for mode %d", mode);
616 enc = &newkeys[mode]->enc;
617 mac = &newkeys[mode]->mac;
618 comp = &newkeys[mode]->comp;
621 DBG(debug("cipher_init_context: %d", mode));
622 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
623 enc->iv, enc->block_size, crypt_type);
624 /* Deleting the keys does not gain extra security */
625 /* memset(enc->iv, 0, enc->block_size);
626 memset(enc->key, 0, enc->key_len); */
627 if (comp->type != 0 && comp->enabled == 0) {
628 packet_init_compression();
629 if (mode == MODE_OUT)
630 buffer_compress_init_send(6);
632 buffer_compress_init_recv();
636 * The 2^(blocksize*2) limit is too expensive for 3DES,
637 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
639 if (enc->block_size >= 16)
640 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
642 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
644 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
648 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
651 packet_send2_wrapped(void)
653 u_char type, *cp, *macbuf = NULL;
655 u_int packet_length = 0;
663 if (newkeys[MODE_OUT] != NULL) {
664 enc = &newkeys[MODE_OUT]->enc;
665 mac = &newkeys[MODE_OUT]->mac;
666 comp = &newkeys[MODE_OUT]->comp;
668 block_size = enc ? enc->block_size : 8;
670 cp = buffer_ptr(&outgoing_packet);
674 fprintf(stderr, "plain: ");
675 buffer_dump(&outgoing_packet);
678 if (comp && comp->enabled) {
679 len = buffer_len(&outgoing_packet);
680 /* skip header, compress only payload */
681 buffer_consume(&outgoing_packet, 5);
682 buffer_clear(&compression_buffer);
683 buffer_compress(&outgoing_packet, &compression_buffer);
684 buffer_clear(&outgoing_packet);
685 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
686 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
687 buffer_len(&compression_buffer));
688 DBG(debug("compression: raw %d compressed %d", len,
689 buffer_len(&outgoing_packet)));
692 /* sizeof (packet_len + pad_len + payload) */
693 len = buffer_len(&outgoing_packet);
696 * calc size of padding, alloc space, get random data,
697 * minimum padding is 4 bytes
699 padlen = block_size - (len % block_size);
701 padlen += block_size;
703 /* will wrap if extra_pad+padlen > 255 */
704 extra_pad = roundup(extra_pad, block_size);
705 pad = extra_pad - ((len + padlen) % extra_pad);
706 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
707 pad, len, padlen, extra_pad);
711 cp = buffer_append_space(&outgoing_packet, padlen);
712 if (enc && !send_context.plaintext) {
714 for (i = 0; i < padlen; i++) {
722 memset(cp, 0, padlen);
724 /* packet_length includes payload, padding and padding length field */
725 packet_length = buffer_len(&outgoing_packet) - 4;
726 cp = buffer_ptr(&outgoing_packet);
727 PUT_32BIT(cp, packet_length);
729 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
731 /* compute MAC over seqnr and packet(length fields, payload, padding) */
732 if (mac && mac->enabled) {
733 macbuf = mac_compute(mac, p_send.seqnr,
734 buffer_ptr(&outgoing_packet),
735 buffer_len(&outgoing_packet));
736 DBG(debug("done calc MAC out #%d", p_send.seqnr));
738 /* encrypt packet and append to output buffer. */
739 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
740 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
741 buffer_len(&outgoing_packet));
742 /* append unencrypted MAC */
743 if (mac && mac->enabled)
744 buffer_append(&output, (char *)macbuf, mac->mac_len);
746 fprintf(stderr, "encrypted: ");
747 buffer_dump(&output);
749 /* increment sequence number for outgoing packets */
750 if (++p_send.seqnr == 0)
751 logit("outgoing seqnr wraps around");
752 if (++p_send.packets == 0)
753 if (!(datafellows & SSH_BUG_NOREKEY))
754 fatal("XXX too many packets with same key");
755 p_send.blocks += (packet_length + 4) / block_size;
756 buffer_clear(&outgoing_packet);
758 if (type == SSH2_MSG_NEWKEYS)
759 set_newkeys(MODE_OUT);
765 static int rekeying = 0;
769 cp = buffer_ptr(&outgoing_packet);
772 /* during rekeying we can only send key exchange messages */
774 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
775 (type <= SSH2_MSG_TRANSPORT_MAX))) {
776 debug("enqueue packet: %u", type);
777 p = xmalloc(sizeof(*p));
779 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
780 buffer_init(&outgoing_packet);
781 TAILQ_INSERT_TAIL(&outgoing, p, next);
786 /* rekeying starts with sending KEXINIT */
787 if (type == SSH2_MSG_KEXINIT)
790 packet_send2_wrapped();
792 /* after a NEWKEYS message we can send the complete queue */
793 if (type == SSH2_MSG_NEWKEYS) {
795 while ((p = TAILQ_FIRST(&outgoing))) {
797 debug("dequeue packet: %u", type);
798 buffer_free(&outgoing_packet);
799 memcpy(&outgoing_packet, &p->payload,
801 TAILQ_REMOVE(&outgoing, p, next);
803 packet_send2_wrapped();
815 DBG(debug("packet_send done"));
819 * Waits until a packet has been received, and returns its type. Note that
820 * no other data is processed until this returns, so this function should not
821 * be used during the interactive session.
825 packet_read_seqnr(u_int32_t *seqnr_p)
830 DBG(debug("packet_read()"));
832 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) *
835 /* Since we are blocking, ensure that all written packets have been sent. */
838 /* Stay in the loop until we have received a complete packet. */
840 /* Try to read a packet from the buffer. */
841 type = packet_read_poll_seqnr(seqnr_p);
843 type == SSH_SMSG_SUCCESS
844 || type == SSH_SMSG_FAILURE
845 || type == SSH_CMSG_EOF
846 || type == SSH_CMSG_EXIT_CONFIRMATION))
848 /* If we got a packet, return it. */
849 if (type != SSH_MSG_NONE) {
854 * Otherwise, wait for some data to arrive, add it to the
855 * buffer, and try again.
857 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
859 FD_SET(connection_in, setp);
861 /* Wait for some data to arrive. */
862 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
863 (errno == EAGAIN || errno == EINTR))
866 /* Read data from the socket. */
867 len = read(connection_in, buf, sizeof(buf));
869 logit("Connection closed by %.200s", get_remote_ipaddr());
873 fatal("Read from socket failed: %.100s", strerror(errno));
874 /* Append it to the buffer. */
875 packet_process_incoming(buf, len);
883 return packet_read_seqnr(NULL);
887 * Waits until a packet has been received, verifies that its type matches
888 * that given, and gives a fatal error and exits if there is a mismatch.
892 packet_read_expect(int expected_type)
896 type = packet_read();
897 if (type != expected_type)
898 packet_disconnect("Protocol error: expected packet type %d, got %d",
899 expected_type, type);
902 /* Checks if a full packet is available in the data received so far via
903 * packet_process_incoming. If so, reads the packet; otherwise returns
904 * SSH_MSG_NONE. This does not wait for data from the connection.
906 * SSH_MSG_DISCONNECT is handled specially here. Also,
907 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
912 packet_read_poll1(void)
914 u_int len, padded_len;
916 u_int checksum, stored_checksum;
918 /* Check if input size is less than minimum packet size. */
919 if (buffer_len(&input) < 4 + 8)
921 /* Get length of incoming packet. */
922 cp = buffer_ptr(&input);
924 if (len < 1 + 2 + 2 || len > 256 * 1024)
925 packet_disconnect("Bad packet length %u.", len);
926 padded_len = (len + 8) & ~7;
928 /* Check if the packet has been entirely received. */
929 if (buffer_len(&input) < 4 + padded_len)
932 /* The entire packet is in buffer. */
934 /* Consume packet length. */
935 buffer_consume(&input, 4);
938 * Cryptographic attack detector for ssh
939 * (C)1998 CORE-SDI, Buenos Aires Argentina
940 * Ariel Futoransky(futo@core-sdi.com)
942 if (!receive_context.plaintext &&
943 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED)
944 packet_disconnect("crc32 compensation attack: network attack detected");
946 /* Decrypt data to incoming_packet. */
947 buffer_clear(&incoming_packet);
948 cp = buffer_append_space(&incoming_packet, padded_len);
949 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
951 buffer_consume(&input, padded_len);
954 fprintf(stderr, "read_poll plain: ");
955 buffer_dump(&incoming_packet);
958 /* Compute packet checksum. */
959 checksum = ssh_crc32(buffer_ptr(&incoming_packet),
960 buffer_len(&incoming_packet) - 4);
963 buffer_consume(&incoming_packet, 8 - len % 8);
965 /* Test check bytes. */
966 if (len != buffer_len(&incoming_packet))
967 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
968 len, buffer_len(&incoming_packet));
970 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
971 stored_checksum = GET_32BIT(cp);
972 if (checksum != stored_checksum)
973 packet_disconnect("Corrupted check bytes on input.");
974 buffer_consume_end(&incoming_packet, 4);
976 if (packet_compression) {
977 buffer_clear(&compression_buffer);
978 buffer_uncompress(&incoming_packet, &compression_buffer);
979 buffer_clear(&incoming_packet);
980 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
981 buffer_len(&compression_buffer));
983 type = buffer_get_char(&incoming_packet);
988 packet_read_poll2(u_int32_t *seqnr_p)
990 static u_int packet_length = 0;
992 u_char *macbuf, *cp, type;
993 int maclen, block_size;
998 if (newkeys[MODE_IN] != NULL) {
999 enc = &newkeys[MODE_IN]->enc;
1000 mac = &newkeys[MODE_IN]->mac;
1001 comp = &newkeys[MODE_IN]->comp;
1003 maclen = mac && mac->enabled ? mac->mac_len : 0;
1004 block_size = enc ? enc->block_size : 8;
1006 if (packet_length == 0) {
1008 * check if input size is less than the cipher block size,
1009 * decrypt first block and extract length of incoming packet
1011 if (buffer_len(&input) < block_size)
1012 return SSH_MSG_NONE;
1013 buffer_clear(&incoming_packet);
1014 cp = buffer_append_space(&incoming_packet, block_size);
1015 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1017 cp = buffer_ptr(&incoming_packet);
1018 packet_length = GET_32BIT(cp);
1019 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1021 buffer_dump(&incoming_packet);
1023 packet_disconnect("Bad packet length %u.", packet_length);
1025 DBG(debug("input: packet len %u", packet_length+4));
1026 buffer_consume(&input, block_size);
1028 /* we have a partial packet of block_size bytes */
1029 need = 4 + packet_length - block_size;
1030 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1032 if (need % block_size != 0)
1033 fatal("padding error: need %d block %d mod %d",
1034 need, block_size, need % block_size);
1036 * check if the entire packet has been received and
1037 * decrypt into incoming_packet
1039 if (buffer_len(&input) < need + maclen)
1040 return SSH_MSG_NONE;
1042 fprintf(stderr, "read_poll enc/full: ");
1043 buffer_dump(&input);
1045 cp = buffer_append_space(&incoming_packet, need);
1046 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1047 buffer_consume(&input, need);
1049 * compute MAC over seqnr and packet,
1050 * increment sequence number for incoming packet
1052 if (mac && mac->enabled) {
1053 macbuf = mac_compute(mac, p_read.seqnr,
1054 buffer_ptr(&incoming_packet),
1055 buffer_len(&incoming_packet));
1056 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1057 packet_disconnect("Corrupted MAC on input.");
1058 DBG(debug("MAC #%d ok", p_read.seqnr));
1059 buffer_consume(&input, mac->mac_len);
1061 if (seqnr_p != NULL)
1062 *seqnr_p = p_read.seqnr;
1063 if (++p_read.seqnr == 0)
1064 logit("incoming seqnr wraps around");
1065 if (++p_read.packets == 0)
1066 if (!(datafellows & SSH_BUG_NOREKEY))
1067 fatal("XXX too many packets with same key");
1068 p_read.blocks += (packet_length + 4) / block_size;
1071 cp = buffer_ptr(&incoming_packet);
1073 DBG(debug("input: padlen %d", padlen));
1075 packet_disconnect("Corrupted padlen %d on input.", padlen);
1077 /* skip packet size + padlen, discard padding */
1078 buffer_consume(&incoming_packet, 4 + 1);
1079 buffer_consume_end(&incoming_packet, padlen);
1081 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1082 if (comp && comp->enabled) {
1083 buffer_clear(&compression_buffer);
1084 buffer_uncompress(&incoming_packet, &compression_buffer);
1085 buffer_clear(&incoming_packet);
1086 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1087 buffer_len(&compression_buffer));
1088 DBG(debug("input: len after de-compress %d",
1089 buffer_len(&incoming_packet)));
1092 * get packet type, implies consume.
1093 * return length of payload (without type field)
1095 type = buffer_get_char(&incoming_packet);
1096 if (type == SSH2_MSG_NEWKEYS)
1097 set_newkeys(MODE_IN);
1099 fprintf(stderr, "read/plain[%d]:\r\n", type);
1100 buffer_dump(&incoming_packet);
1102 /* reset for next packet */
1108 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1110 u_int reason, seqnr;
1116 type = packet_read_poll2(seqnr_p);
1118 DBG(debug("received packet type %d", type));
1120 case SSH2_MSG_IGNORE:
1122 case SSH2_MSG_DEBUG:
1124 msg = packet_get_string(NULL);
1125 debug("Remote: %.900s", msg);
1127 msg = packet_get_string(NULL);
1130 case SSH2_MSG_DISCONNECT:
1131 reason = packet_get_int();
1132 msg = packet_get_string(NULL);
1133 logit("Received disconnect from %s: %u: %.400s",
1134 get_remote_ipaddr(), reason, msg);
1138 case SSH2_MSG_UNIMPLEMENTED:
1139 seqnr = packet_get_int();
1140 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1148 type = packet_read_poll1();
1150 case SSH_MSG_IGNORE:
1153 msg = packet_get_string(NULL);
1154 debug("Remote: %.900s", msg);
1157 case SSH_MSG_DISCONNECT:
1158 msg = packet_get_string(NULL);
1159 logit("Received disconnect from %s: %.400s",
1160 get_remote_ipaddr(), msg);
1166 DBG(debug("received packet type %d", type));
1175 packet_read_poll(void)
1177 return packet_read_poll_seqnr(NULL);
1181 * Buffers the given amount of input characters. This is intended to be used
1182 * together with packet_read_poll.
1186 packet_process_incoming(const char *buf, u_int len)
1188 buffer_append(&input, buf, len);
1191 /* Returns a character from the packet. */
1194 packet_get_char(void)
1198 buffer_get(&incoming_packet, &ch, 1);
1202 /* Returns an integer from the packet data. */
1205 packet_get_int(void)
1207 return buffer_get_int(&incoming_packet);
1211 * Returns an arbitrary precision integer from the packet data. The integer
1212 * must have been initialized before this call.
1216 packet_get_bignum(BIGNUM * value)
1218 buffer_get_bignum(&incoming_packet, value);
1222 packet_get_bignum2(BIGNUM * value)
1224 buffer_get_bignum2(&incoming_packet, value);
1228 packet_get_raw(int *length_ptr)
1230 int bytes = buffer_len(&incoming_packet);
1232 if (length_ptr != NULL)
1233 *length_ptr = bytes;
1234 return buffer_ptr(&incoming_packet);
1238 packet_remaining(void)
1240 return buffer_len(&incoming_packet);
1244 * Returns a string from the packet data. The string is allocated using
1245 * xmalloc; it is the responsibility of the calling program to free it when
1246 * no longer needed. The length_ptr argument may be NULL, or point to an
1247 * integer into which the length of the string is stored.
1251 packet_get_string(u_int *length_ptr)
1253 return buffer_get_string(&incoming_packet, length_ptr);
1257 * Sends a diagnostic message from the server to the client. This message
1258 * can be sent at any time (but not while constructing another message). The
1259 * message is printed immediately, but only if the client is being executed
1260 * in verbose mode. These messages are primarily intended to ease debugging
1261 * authentication problems. The length of the formatted message must not
1262 * exceed 1024 bytes. This will automatically call packet_write_wait.
1266 packet_send_debug(const char *fmt,...)
1271 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1274 va_start(args, fmt);
1275 vsnprintf(buf, sizeof(buf), fmt, args);
1279 packet_start(SSH2_MSG_DEBUG);
1280 packet_put_char(0); /* bool: always display */
1281 packet_put_cstring(buf);
1282 packet_put_cstring("");
1284 packet_start(SSH_MSG_DEBUG);
1285 packet_put_cstring(buf);
1288 packet_write_wait();
1292 * Logs the error plus constructs and sends a disconnect packet, closes the
1293 * connection, and exits. This function never returns. The error message
1294 * should not contain a newline. The length of the formatted message must
1295 * not exceed 1024 bytes.
1299 packet_disconnect(const char *fmt,...)
1303 static int disconnecting = 0;
1305 if (disconnecting) /* Guard against recursive invocations. */
1306 fatal("packet_disconnect called recursively.");
1310 * Format the message. Note that the caller must make sure the
1311 * message is of limited size.
1313 va_start(args, fmt);
1314 vsnprintf(buf, sizeof(buf), fmt, args);
1317 /* Display the error locally */
1318 logit("Disconnecting: %.100s", buf);
1320 /* Send the disconnect message to the other side, and wait for it to get sent. */
1322 packet_start(SSH2_MSG_DISCONNECT);
1323 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1324 packet_put_cstring(buf);
1325 packet_put_cstring("");
1327 packet_start(SSH_MSG_DISCONNECT);
1328 packet_put_cstring(buf);
1331 packet_write_wait();
1333 /* Stop listening for connections. */
1334 channel_close_all();
1336 /* Close the connection. */
1341 /* Checks if there is any buffered output, and tries to write some of the output. */
1344 packet_write_poll(void)
1346 int len = buffer_len(&output);
1349 len = write(connection_out, buffer_ptr(&output), len);
1351 if (errno == EAGAIN)
1354 fatal("Write failed: %.100s", strerror(errno));
1356 buffer_consume(&output, len);
1361 * Calls packet_write_poll repeatedly until all pending output data has been
1366 packet_write_wait(void)
1370 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) *
1372 packet_write_poll();
1373 while (packet_have_data_to_write()) {
1374 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1376 FD_SET(connection_out, setp);
1377 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1378 (errno == EAGAIN || errno == EINTR))
1380 packet_write_poll();
1385 /* Returns true if there is buffered data to write to the connection. */
1388 packet_have_data_to_write(void)
1390 return buffer_len(&output) != 0;
1393 /* Returns true if there is not too much data to write to the connection. */
1396 packet_not_very_much_data_to_write(void)
1398 if (interactive_mode)
1399 return buffer_len(&output) < 16384;
1401 return buffer_len(&output) < 128 * 1024;
1406 packet_set_tos(int interactive)
1408 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1409 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1411 if (!packet_connection_is_on_socket() ||
1412 !packet_connection_is_ipv4())
1414 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1416 error("setsockopt IP_TOS %d: %.100s:",
1417 tos, strerror(errno));
1421 /* Informs that the current session is interactive. Sets IP flags for that. */
1424 packet_set_interactive(int interactive)
1426 static int called = 0;
1432 /* Record that we are in interactive mode. */
1433 interactive_mode = interactive;
1435 /* Only set socket options if using a socket. */
1436 if (!packet_connection_is_on_socket())
1439 set_nodelay(connection_in);
1440 packet_set_tos(interactive);
1443 /* Returns true if the current connection is interactive. */
1446 packet_is_interactive(void)
1448 return interactive_mode;
1452 packet_set_maxsize(u_int s)
1454 static int called = 0;
1457 logit("packet_set_maxsize: called twice: old %d new %d",
1458 max_packet_size, s);
1461 if (s < 4 * 1024 || s > 1024 * 1024) {
1462 logit("packet_set_maxsize: bad size %d", s);
1466 debug("packet_set_maxsize: setting to %d", s);
1467 max_packet_size = s;
1471 /* roundup current message to pad bytes */
1473 packet_add_padding(u_char pad)
1479 * 9.2. Ignored Data Message
1481 * byte SSH_MSG_IGNORE
1484 * All implementations MUST understand (and ignore) this message at any
1485 * time (after receiving the protocol version). No implementation is
1486 * required to send them. This message can be used as an additional
1487 * protection measure against advanced traffic analysis techniques.
1490 packet_send_ignore(int nbytes)
1495 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1496 packet_put_int(nbytes);
1497 for (i = 0; i < nbytes; i++) {
1500 packet_put_char(rnd & 0xff);
1505 #define MAX_PACKETS (1U<<31)
1507 packet_need_rekeying(void)
1509 if (datafellows & SSH_BUG_NOREKEY)
1512 (p_send.packets > MAX_PACKETS) ||
1513 (p_read.packets > MAX_PACKETS) ||
1514 (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1515 (max_blocks_in && (p_read.blocks > max_blocks_in));
1519 packet_set_rekey_limit(u_int32_t bytes)
1521 rekey_limit = bytes;