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 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 1.54 2001/02/28 21:27:47 markus Exp $");
70 * This variable contains the file descriptors used for communicating with
71 * the other side. connection_in is used for reading; connection_out for
72 * writing. These can be the same descriptor, in which case it is assumed to
75 static int connection_in = -1;
76 static int connection_out = -1;
79 * Cipher type. This value is only used to determine whether to pad the
80 * packets with zeroes or random data.
82 static int cipher_type = SSH_CIPHER_NONE;
84 /* Protocol flags for the remote side. */
85 static u_int remote_protocol_flags = 0;
87 /* Encryption context for receiving data. This is only used for decryption. */
88 static CipherContext receive_context;
90 /* Encryption context for sending data. This is only used for encryption. */
91 static CipherContext send_context;
93 /* Buffer for raw input data from the socket. */
96 /* Buffer for raw output data going to the socket. */
99 /* Buffer for the partial outgoing packet being constructed. */
100 static Buffer outgoing_packet;
102 /* Buffer for the incoming packet currently being processed. */
103 static Buffer incoming_packet;
105 /* Scratch buffer for packet compression/decompression. */
106 static Buffer compression_buffer;
108 /* Flag indicating whether packet compression/decompression is enabled. */
109 static int packet_compression = 0;
111 /* default maximum packet size */
112 int max_packet_size = 32768;
114 /* Flag indicating whether this module has been initialized. */
115 static int initialized = 0;
117 /* Set to true if the connection is interactive. */
118 static int interactive_mode = 0;
120 /* True if SSH2 packet format is used */
121 int use_ssh2_packet_format = 0;
123 /* Session key information for Encryption and MAC */
127 packet_set_kex(Kex *k)
129 if( k->mac[MODE_IN ].key == NULL ||
130 k->enc[MODE_IN ].key == NULL ||
131 k->enc[MODE_IN ].iv == NULL ||
132 k->mac[MODE_OUT].key == NULL ||
133 k->enc[MODE_OUT].key == NULL ||
134 k->enc[MODE_OUT].iv == NULL)
139 clear_enc_keys(Enc *enc, int len)
141 memset(enc->iv, 0, len);
142 memset(enc->key, 0, len);
149 packet_set_ssh2_format(void)
151 DBG(debug("use_ssh2_packet_format"));
152 use_ssh2_packet_format = 1;
156 * Sets the descriptors used for communication. Disables encryption until
157 * packet_set_encryption_key is called.
160 packet_set_connection(int fd_in, int fd_out)
162 Cipher *none = cipher_by_name("none");
164 fatal("packet_set_connection: cannot load cipher 'none'");
165 connection_in = fd_in;
166 connection_out = fd_out;
167 cipher_type = SSH_CIPHER_NONE;
168 cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0);
169 cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0);
173 buffer_init(&output);
174 buffer_init(&outgoing_packet);
175 buffer_init(&incoming_packet);
177 /* Kludge: arrange the close function to be called from fatal(). */
178 fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
181 /* Returns 1 if remote host is connected via socket, 0 if not. */
184 packet_connection_is_on_socket()
186 struct sockaddr_storage from, to;
187 socklen_t fromlen, tolen;
189 /* filedescriptors in and out are the same, so it's a socket */
190 if (connection_in == connection_out)
192 fromlen = sizeof(from);
193 memset(&from, 0, sizeof(from));
194 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
197 memset(&to, 0, sizeof(to));
198 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
200 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
202 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
207 /* returns 1 if connection is via ipv4 */
210 packet_connection_is_ipv4()
212 struct sockaddr_storage to;
213 socklen_t tolen = sizeof(to);
215 memset(&to, 0, sizeof(to));
216 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
218 if (to.ss_family != AF_INET)
223 /* Sets the connection into non-blocking mode. */
226 packet_set_nonblocking()
228 /* Set the socket into non-blocking mode. */
229 if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
230 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
232 if (connection_out != connection_in) {
233 if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
234 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
238 /* Returns the socket used for reading. */
241 packet_get_connection_in()
243 return connection_in;
246 /* Returns the descriptor used for writing. */
249 packet_get_connection_out()
251 return connection_out;
254 /* Closes the connection and clears and frees internal data structures. */
262 if (connection_in == connection_out) {
263 shutdown(connection_out, SHUT_RDWR);
264 close(connection_out);
266 close(connection_in);
267 close(connection_out);
270 buffer_free(&output);
271 buffer_free(&outgoing_packet);
272 buffer_free(&incoming_packet);
273 if (packet_compression) {
274 buffer_free(&compression_buffer);
275 buffer_compress_uninit();
279 /* Sets remote side protocol flags. */
282 packet_set_protocol_flags(u_int protocol_flags)
284 remote_protocol_flags = protocol_flags;
285 channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0);
288 /* Returns the remote protocol flags set earlier by the above function. */
291 packet_get_protocol_flags()
293 return remote_protocol_flags;
297 * Starts packet compression from the next packet on in both directions.
298 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
301 /*** XXXXX todo: kex means re-init */
303 packet_start_compression(int level)
305 if (packet_compression)
306 fatal("Compression already enabled.");
307 packet_compression = 1;
308 buffer_init(&compression_buffer);
309 buffer_compress_init(level);
313 * Encrypts the given number of bytes, copying from src to dest. bytes is
314 * known to be a multiple of 8.
318 packet_encrypt(CipherContext * cc, void *dest, void *src,
321 cipher_encrypt(cc, dest, src, bytes);
325 * Decrypts the given number of bytes, copying from src to dest. bytes is
326 * known to be a multiple of 8.
330 packet_decrypt(CipherContext *context, void *dest, void *src, u_int bytes)
333 * Cryptographic attack detector for ssh - Modifications for packet.c
334 * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com)
337 context->cipher->number != SSH_CIPHER_NONE &&
338 detect_attack(src, bytes, NULL) == DEATTACK_DETECTED)
339 packet_disconnect("crc32 compensation attack: network attack detected");
341 cipher_decrypt(context, dest, src, bytes);
345 * Causes any further packets to be encrypted using the given key. The same
346 * key is used for both sending and reception. However, both directions are
347 * encrypted independently of each other.
351 packet_set_encryption_key(const u_char *key, u_int keylen,
354 Cipher *cipher = cipher_by_number(number);
356 fatal("packet_set_encryption_key: unknown cipher number %d", number);
358 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
359 cipher_init(&receive_context, cipher, key, keylen, NULL, 0);
360 cipher_init(&send_context, cipher, key, keylen, NULL, 0);
363 /* Starts constructing a packet to send. */
366 packet_start1(int type)
370 buffer_clear(&outgoing_packet);
373 buffer_append(&outgoing_packet, buf, 9);
377 packet_start2(int type)
381 buffer_clear(&outgoing_packet);
382 memset(buf, 0, sizeof buf);
383 /* buf[0..3] = payload_len; */
384 /* buf[4] = pad_len; */
385 buf[5] = type & 0xff;
386 buffer_append(&outgoing_packet, buf, sizeof buf);
390 packet_start(int type)
392 DBG(debug("packet_start[%d]",type));
393 if (use_ssh2_packet_format)
399 /* Appends a character to the packet data. */
402 packet_put_char(int value)
405 buffer_append(&outgoing_packet, &ch, 1);
408 /* Appends an integer to the packet data. */
411 packet_put_int(u_int value)
413 buffer_put_int(&outgoing_packet, value);
416 /* Appends a string to packet data. */
419 packet_put_string(const char *buf, u_int len)
421 buffer_put_string(&outgoing_packet, buf, len);
424 packet_put_cstring(const char *str)
426 buffer_put_string(&outgoing_packet, str, strlen(str));
430 packet_put_raw(const char *buf, u_int len)
432 buffer_append(&outgoing_packet, buf, len);
436 /* Appends an arbitrary precision integer to packet data. */
439 packet_put_bignum(BIGNUM * value)
441 buffer_put_bignum(&outgoing_packet, value);
444 packet_put_bignum2(BIGNUM * value)
446 buffer_put_bignum2(&outgoing_packet, value);
450 * Finalizes and sends the packet. If the encryption key has been set,
451 * encrypts the packet before sending.
463 * If using packet compression, compress the payload of the outgoing
466 if (packet_compression) {
467 buffer_clear(&compression_buffer);
469 buffer_consume(&outgoing_packet, 8);
471 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
472 buffer_compress(&outgoing_packet, &compression_buffer);
473 buffer_clear(&outgoing_packet);
474 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
475 buffer_len(&compression_buffer));
477 /* Compute packet length without padding (add checksum, remove padding). */
478 len = buffer_len(&outgoing_packet) + 4 - 8;
480 /* Insert padding. Initialized to zero in packet_start1() */
481 padding = 8 - len % 8;
482 if (cipher_type != SSH_CIPHER_NONE) {
483 cp = buffer_ptr(&outgoing_packet);
484 for (i = 0; i < padding; i++) {
487 cp[7 - i] = rand & 0xff;
491 buffer_consume(&outgoing_packet, 8 - padding);
493 /* Add check bytes. */
494 checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet),
495 buffer_len(&outgoing_packet));
496 PUT_32BIT(buf, checksum);
497 buffer_append(&outgoing_packet, buf, 4);
500 fprintf(stderr, "packet_send plain: ");
501 buffer_dump(&outgoing_packet);
504 /* Append to output. */
506 buffer_append(&output, buf, 4);
507 buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
508 packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
509 buffer_len(&outgoing_packet));
512 fprintf(stderr, "encrypted: ");
513 buffer_dump(&output);
516 buffer_clear(&outgoing_packet);
519 * Note that the packet is now only buffered in output. It won\'t be
520 * actually sent until packet_write_wait or packet_write_poll is
526 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
531 static u_int32_t seqnr = 0;
532 u_char *macbuf = NULL;
534 u_int packet_length = 0;
535 u_int i, padlen, len;
544 enc = &kex->enc[MODE_OUT];
545 mac = &kex->mac[MODE_OUT];
546 comp = &kex->comp[MODE_OUT];
548 block_size = enc ? enc->cipher->block_size : 8;
550 cp = buffer_ptr(&outgoing_packet);
554 fprintf(stderr, "plain: ");
555 buffer_dump(&outgoing_packet);
558 if (comp && comp->enabled) {
559 len = buffer_len(&outgoing_packet);
560 /* skip header, compress only payload */
561 buffer_consume(&outgoing_packet, 5);
562 buffer_clear(&compression_buffer);
563 buffer_compress(&outgoing_packet, &compression_buffer);
564 buffer_clear(&outgoing_packet);
565 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
566 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
567 buffer_len(&compression_buffer));
568 DBG(debug("compression: raw %d compressed %d", len,
569 buffer_len(&outgoing_packet)));
572 /* sizeof (packet_len + pad_len + payload) */
573 len = buffer_len(&outgoing_packet);
576 * calc size of padding, alloc space, get random data,
577 * minimum padding is 4 bytes
579 padlen = block_size - (len % block_size);
581 padlen += block_size;
582 buffer_append_space(&outgoing_packet, &cp, padlen);
583 if (enc && enc->cipher->number != SSH_CIPHER_NONE) {
585 for (i = 0; i < padlen; i++) {
593 memset(cp, 0, padlen);
595 /* packet_length includes payload, padding and padding length field */
596 packet_length = buffer_len(&outgoing_packet) - 4;
597 cp = buffer_ptr(&outgoing_packet);
598 PUT_32BIT(cp, packet_length);
599 cp[4] = padlen & 0xff;
600 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
602 /* compute MAC over seqnr and packet(length fields, payload, padding) */
603 if (mac && mac->enabled) {
604 macbuf = mac_compute(mac, seqnr,
605 (u_char *) buffer_ptr(&outgoing_packet),
606 buffer_len(&outgoing_packet));
607 DBG(debug("done calc MAC out #%d", seqnr));
609 /* encrypt packet and append to output buffer. */
610 buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
611 packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
612 buffer_len(&outgoing_packet));
613 /* append unencrypted MAC */
614 if (mac && mac->enabled)
615 buffer_append(&output, (char *)macbuf, mac->mac_len);
617 fprintf(stderr, "encrypted: ");
618 buffer_dump(&output);
620 /* increment sequence number for outgoing packets */
622 log("outgoing seqnr wraps around");
623 buffer_clear(&outgoing_packet);
625 if (type == SSH2_MSG_NEWKEYS) {
626 if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
627 fatal("packet_send2: no KEX");
630 DBG(debug("cipher_init send_context"));
631 cipher_init(&send_context, enc->cipher,
632 enc->key, enc->cipher->key_len,
633 enc->iv, enc->cipher->block_size);
634 clear_enc_keys(enc, kex->we_need);
635 if (comp->type != 0 && comp->enabled == 0) {
637 if (! packet_compression)
638 packet_start_compression(6);
646 if (use_ssh2_packet_format)
650 DBG(debug("packet_send done"));
654 * Waits until a packet has been received, and returns its type. Note that
655 * no other data is processed until this returns, so this function should not
656 * be used during the interactive session.
660 packet_read(int *payload_len_ptr)
665 DBG(debug("packet_read()"));
667 /* Since we are blocking, ensure that all written packets have been sent. */
670 /* Stay in the loop until we have received a complete packet. */
672 /* Try to read a packet from the buffer. */
673 type = packet_read_poll(payload_len_ptr);
674 if (!use_ssh2_packet_format && (
675 type == SSH_SMSG_SUCCESS
676 || type == SSH_SMSG_FAILURE
677 || type == SSH_CMSG_EOF
678 || type == SSH_CMSG_EXIT_CONFIRMATION))
679 packet_integrity_check(*payload_len_ptr, 0, type);
680 /* If we got a packet, return it. */
681 if (type != SSH_MSG_NONE)
684 * Otherwise, wait for some data to arrive, add it to the
685 * buffer, and try again.
688 FD_SET(connection_in, &set);
690 /* Wait for some data to arrive. */
691 while (select(connection_in + 1, &set, NULL, NULL, NULL) == -1 &&
692 (errno == EAGAIN || errno == EINTR))
695 /* Read data from the socket. */
696 len = read(connection_in, buf, sizeof(buf));
698 log("Connection closed by %.200s", get_remote_ipaddr());
702 fatal("Read from socket failed: %.100s", strerror(errno));
703 /* Append it to the buffer. */
704 packet_process_incoming(buf, len);
710 * Waits until a packet has been received, verifies that its type matches
711 * that given, and gives a fatal error and exits if there is a mismatch.
715 packet_read_expect(int *payload_len_ptr, int expected_type)
719 type = packet_read(payload_len_ptr);
720 if (type != expected_type)
721 packet_disconnect("Protocol error: expected packet type %d, got %d",
722 expected_type, type);
725 /* Checks if a full packet is available in the data received so far via
726 * packet_process_incoming. If so, reads the packet; otherwise returns
727 * SSH_MSG_NONE. This does not wait for data from the connection.
729 * SSH_MSG_DISCONNECT is handled specially here. Also,
730 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
733 * The returned payload_len does include space consumed by:
741 packet_read_poll1(int *payload_len_ptr)
743 u_int len, padded_len;
746 u_int checksum, stored_checksum;
748 /* Check if input size is less than minimum packet size. */
749 if (buffer_len(&input) < 4 + 8)
751 /* Get length of incoming packet. */
752 ucp = (u_char *) buffer_ptr(&input);
753 len = GET_32BIT(ucp);
754 if (len < 1 + 2 + 2 || len > 256 * 1024)
755 packet_disconnect("Bad packet length %d.", len);
756 padded_len = (len + 8) & ~7;
758 /* Check if the packet has been entirely received. */
759 if (buffer_len(&input) < 4 + padded_len)
762 /* The entire packet is in buffer. */
764 /* Consume packet length. */
765 buffer_consume(&input, 4);
767 /* Copy data to incoming_packet. */
768 buffer_clear(&incoming_packet);
769 buffer_append_space(&incoming_packet, &cp, padded_len);
770 packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
771 buffer_consume(&input, padded_len);
774 fprintf(stderr, "read_poll plain: ");
775 buffer_dump(&incoming_packet);
778 /* Compute packet checksum. */
779 checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet),
780 buffer_len(&incoming_packet) - 4);
783 buffer_consume(&incoming_packet, 8 - len % 8);
785 /* Test check bytes. */
787 if (len != buffer_len(&incoming_packet))
788 packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
789 len, buffer_len(&incoming_packet));
791 ucp = (u_char *) buffer_ptr(&incoming_packet) + len - 4;
792 stored_checksum = GET_32BIT(ucp);
793 if (checksum != stored_checksum)
794 packet_disconnect("Corrupted check bytes on input.");
795 buffer_consume_end(&incoming_packet, 4);
797 /* If using packet compression, decompress the packet. */
798 if (packet_compression) {
799 buffer_clear(&compression_buffer);
800 buffer_uncompress(&incoming_packet, &compression_buffer);
801 buffer_clear(&incoming_packet);
802 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
803 buffer_len(&compression_buffer));
805 /* Get packet type. */
806 buffer_get(&incoming_packet, &buf[0], 1);
808 /* Return length of payload (without type field). */
809 *payload_len_ptr = buffer_len(&incoming_packet);
812 return (u_char) buf[0];
816 packet_read_poll2(int *payload_len_ptr)
818 static u_int32_t seqnr = 0;
819 static u_int packet_length = 0;
821 u_char buf[8], *macbuf;
825 int maclen, block_size;
831 enc = &kex->enc[MODE_IN];
832 mac = &kex->mac[MODE_IN];
833 comp = &kex->comp[MODE_IN];
835 maclen = mac && mac->enabled ? mac->mac_len : 0;
836 block_size = enc ? enc->cipher->block_size : 8;
838 if (packet_length == 0) {
840 * check if input size is less than the cipher block size,
841 * decrypt first block and extract length of incoming packet
843 if (buffer_len(&input) < block_size)
845 buffer_clear(&incoming_packet);
846 buffer_append_space(&incoming_packet, &cp, block_size);
847 packet_decrypt(&receive_context, cp, buffer_ptr(&input),
849 ucp = (u_char *) buffer_ptr(&incoming_packet);
850 packet_length = GET_32BIT(ucp);
851 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
852 buffer_dump(&incoming_packet);
853 packet_disconnect("Bad packet length %d.", packet_length);
855 DBG(debug("input: packet len %d", packet_length+4));
856 buffer_consume(&input, block_size);
858 /* we have a partial packet of block_size bytes */
859 need = 4 + packet_length - block_size;
860 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
862 if (need % block_size != 0)
863 fatal("padding error: need %d block %d mod %d",
864 need, block_size, need % block_size);
866 * check if the entire packet has been received and
867 * decrypt into incoming_packet
869 if (buffer_len(&input) < need + maclen)
872 fprintf(stderr, "read_poll enc/full: ");
875 buffer_append_space(&incoming_packet, &cp, need);
876 packet_decrypt(&receive_context, cp, buffer_ptr(&input), need);
877 buffer_consume(&input, need);
879 * compute MAC over seqnr and packet,
880 * increment sequence number for incoming packet
882 if (mac && mac->enabled) {
883 macbuf = mac_compute(mac, seqnr,
884 (u_char *) buffer_ptr(&incoming_packet),
885 buffer_len(&incoming_packet));
886 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
887 packet_disconnect("Corrupted MAC on input.");
888 DBG(debug("MAC #%d ok", seqnr));
889 buffer_consume(&input, mac->mac_len);
892 log("incoming seqnr wraps around");
895 cp = buffer_ptr(&incoming_packet) + 4;
897 DBG(debug("input: padlen %d", padlen));
899 packet_disconnect("Corrupted padlen %d on input.", padlen);
901 /* skip packet size + padlen, discard padding */
902 buffer_consume(&incoming_packet, 4 + 1);
903 buffer_consume_end(&incoming_packet, padlen);
905 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
906 if (comp && comp->enabled) {
907 buffer_clear(&compression_buffer);
908 buffer_uncompress(&incoming_packet, &compression_buffer);
909 buffer_clear(&incoming_packet);
910 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
911 buffer_len(&compression_buffer));
912 DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
915 * get packet type, implies consume.
916 * return length of payload (without type field)
918 buffer_get(&incoming_packet, (char *)&buf[0], 1);
919 *payload_len_ptr = buffer_len(&incoming_packet);
921 /* reset for next packet */
924 /* extract packet type */
925 type = (u_char)buf[0];
927 if (type == SSH2_MSG_NEWKEYS) {
928 if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
929 fatal("packet_read_poll2: no KEX");
932 DBG(debug("cipher_init receive_context"));
933 cipher_init(&receive_context, enc->cipher,
934 enc->key, enc->cipher->key_len,
935 enc->iv, enc->cipher->block_size);
936 clear_enc_keys(enc, kex->we_need);
937 if (comp->type != 0 && comp->enabled == 0) {
939 if (! packet_compression)
940 packet_start_compression(6);
945 fprintf(stderr, "read/plain[%d]:\r\n",type);
946 buffer_dump(&incoming_packet);
952 packet_read_poll(int *payload_len_ptr)
956 int type = use_ssh2_packet_format ?
957 packet_read_poll2(payload_len_ptr):
958 packet_read_poll1(payload_len_ptr);
963 DBG(debug("received packet type %d", type));
965 case SSH2_MSG_IGNORE:
969 msg = packet_get_string(NULL);
970 debug("Remote: %.900s", msg);
972 msg = packet_get_string(NULL);
975 case SSH2_MSG_DISCONNECT:
976 reason = packet_get_int();
977 msg = packet_get_string(NULL);
978 log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(),
992 msg = packet_get_string(NULL);
993 debug("Remote: %.900s", msg);
996 case SSH_MSG_DISCONNECT:
997 msg = packet_get_string(NULL);
998 log("Received disconnect from %s: %.400s", get_remote_ipaddr(),
1005 DBG(debug("received packet type %d", type));
1014 * Buffers the given amount of input characters. This is intended to be used
1015 * together with packet_read_poll.
1019 packet_process_incoming(const char *buf, u_int len)
1021 buffer_append(&input, buf, len);
1024 /* Returns a character from the packet. */
1030 buffer_get(&incoming_packet, &ch, 1);
1034 /* Returns an integer from the packet data. */
1039 return buffer_get_int(&incoming_packet);
1043 * Returns an arbitrary precision integer from the packet data. The integer
1044 * must have been initialized before this call.
1048 packet_get_bignum(BIGNUM * value, int *length_ptr)
1050 *length_ptr = buffer_get_bignum(&incoming_packet, value);
1054 packet_get_bignum2(BIGNUM * value, int *length_ptr)
1056 *length_ptr = buffer_get_bignum2(&incoming_packet, value);
1060 packet_get_raw(int *length_ptr)
1062 int bytes = buffer_len(&incoming_packet);
1063 if (length_ptr != NULL)
1064 *length_ptr = bytes;
1065 return buffer_ptr(&incoming_packet);
1069 packet_remaining(void)
1071 return buffer_len(&incoming_packet);
1075 * Returns a string from the packet data. The string is allocated using
1076 * xmalloc; it is the responsibility of the calling program to free it when
1077 * no longer needed. The length_ptr argument may be NULL, or point to an
1078 * integer into which the length of the string is stored.
1082 packet_get_string(u_int *length_ptr)
1084 return buffer_get_string(&incoming_packet, length_ptr);
1088 * Sends a diagnostic message from the server to the client. This message
1089 * can be sent at any time (but not while constructing another message). The
1090 * message is printed immediately, but only if the client is being executed
1091 * in verbose mode. These messages are primarily intended to ease debugging
1092 * authentication problems. The length of the formatted message must not
1093 * exceed 1024 bytes. This will automatically call packet_write_wait.
1097 packet_send_debug(const char *fmt,...)
1102 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1105 va_start(args, fmt);
1106 vsnprintf(buf, sizeof(buf), fmt, args);
1110 packet_start(SSH2_MSG_DEBUG);
1111 packet_put_char(0); /* bool: always display */
1112 packet_put_cstring(buf);
1113 packet_put_cstring("");
1115 packet_start(SSH_MSG_DEBUG);
1116 packet_put_cstring(buf);
1119 packet_write_wait();
1123 * Logs the error plus constructs and sends a disconnect packet, closes the
1124 * connection, and exits. This function never returns. The error message
1125 * should not contain a newline. The length of the formatted message must
1126 * not exceed 1024 bytes.
1130 packet_disconnect(const char *fmt,...)
1134 static int disconnecting = 0;
1135 if (disconnecting) /* Guard against recursive invocations. */
1136 fatal("packet_disconnect called recursively.");
1140 * Format the message. Note that the caller must make sure the
1141 * message is of limited size.
1143 va_start(args, fmt);
1144 vsnprintf(buf, sizeof(buf), fmt, args);
1147 /* Send the disconnect message to the other side, and wait for it to get sent. */
1149 packet_start(SSH2_MSG_DISCONNECT);
1150 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1151 packet_put_cstring(buf);
1152 packet_put_cstring("");
1154 packet_start(SSH_MSG_DISCONNECT);
1155 packet_put_string(buf, strlen(buf));
1158 packet_write_wait();
1160 /* Stop listening for connections. */
1161 channel_stop_listening();
1163 /* Close the connection. */
1166 /* Display the error locally and exit. */
1167 log("Disconnecting: %.100s", buf);
1171 /* Checks if there is any buffered output, and tries to write some of the output. */
1176 int len = buffer_len(&output);
1178 len = write(connection_out, buffer_ptr(&output), len);
1180 if (errno == EAGAIN)
1183 fatal("Write failed: %.100s", strerror(errno));
1185 buffer_consume(&output, len);
1190 * Calls packet_write_poll repeatedly until all pending output data has been
1197 packet_write_poll();
1198 while (packet_have_data_to_write()) {
1202 FD_SET(connection_out, &set);
1203 while (select(connection_out + 1, NULL, &set, NULL, NULL) == -1 &&
1204 (errno == EAGAIN || errno == EINTR))
1206 packet_write_poll();
1210 /* Returns true if there is buffered data to write to the connection. */
1213 packet_have_data_to_write()
1215 return buffer_len(&output) != 0;
1218 /* Returns true if there is not too much data to write to the connection. */
1221 packet_not_very_much_data_to_write()
1223 if (interactive_mode)
1224 return buffer_len(&output) < 16384;
1226 return buffer_len(&output) < 128 * 1024;
1229 /* Informs that the current session is interactive. Sets IP flags for that. */
1232 packet_set_interactive(int interactive)
1234 static int called = 0;
1235 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1236 int lowdelay = IPTOS_LOWDELAY;
1237 int throughput = IPTOS_THROUGHPUT;
1245 /* Record that we are in interactive mode. */
1246 interactive_mode = interactive;
1248 /* Only set socket options if using a socket. */
1249 if (!packet_connection_is_on_socket())
1252 * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only
1256 * Set IP options for an interactive connection. Use
1257 * IPTOS_LOWDELAY and TCP_NODELAY.
1259 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1260 if (packet_connection_is_ipv4()) {
1261 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS,
1262 (void *) &lowdelay, sizeof(lowdelay)) < 0)
1263 error("setsockopt IPTOS_LOWDELAY: %.100s",
1267 if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on,
1269 error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
1270 } else if (packet_connection_is_ipv4()) {
1272 * Set IP options for a non-interactive connection. Use
1275 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1276 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput,
1277 sizeof(throughput)) < 0)
1278 error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1283 /* Returns true if the current connection is interactive. */
1286 packet_is_interactive()
1288 return interactive_mode;
1292 packet_set_maxsize(int s)
1294 static int called = 0;
1296 log("packet_set_maxsize: called twice: old %d new %d",
1297 max_packet_size, s);
1300 if (s < 4 * 1024 || s > 1024 * 1024) {
1301 log("packet_set_maxsize: bad size %d", s);
1304 log("packet_set_maxsize: setting to %d", s);
1305 max_packet_size = s;
1310 * 9.2. Ignored Data Message
1312 * byte SSH_MSG_IGNORE
1315 * All implementations MUST understand (and ignore) this message at any
1316 * time (after receiving the protocol version). No implementation is
1317 * required to send them. This message can be used as an additional
1318 * protection measure against advanced traffic analysis techniques.
1320 /* size of current + ignore message should be n*sumlen bytes (w/o mac) */
1322 packet_inject_ignore(int sumlen)
1324 int blocksize, padlen, have, need, nb, mini, nbytes;
1327 if (use_ssh2_packet_format == 0)
1330 have = buffer_len(&outgoing_packet);
1331 debug2("packet_inject_ignore: current %d", have);
1333 enc = &kex->enc[MODE_OUT];
1334 blocksize = enc ? enc->cipher->block_size : 8;
1335 padlen = blocksize - (have % blocksize);
1337 padlen += blocksize;
1339 have /= blocksize; /* # of blocks for current message */
1341 nb = roundup(sumlen, blocksize) / blocksize; /* blocks for both */
1342 mini = roundup(5+1+4+4, blocksize) / blocksize; /* minsize ignore msg */
1343 need = nb - (have % nb); /* blocks for ignore */
1346 nbytes = (need - mini) * blocksize; /* size of ignore payload */
1347 debug2("packet_inject_ignore: block %d have %d nb %d mini %d need %d",
1348 blocksize, have, nb, mini, need);
1350 /* enqueue current message and append a ignore message */
1352 packet_send_ignore(nbytes);
1356 packet_send_ignore(int nbytes)
1361 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1362 packet_put_int(nbytes);
1363 for(i = 0; i < nbytes; i++) {
1365 rand = arc4random();
1366 packet_put_char(rand & 0xff);