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 1.65 2001/06/07 20:23:04 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;
78 /* Protocol flags for the remote side. */
79 static u_int remote_protocol_flags = 0;
81 /* Encryption context for receiving data. This is only used for decryption. */
82 static CipherContext receive_context;
84 /* Encryption context for sending data. This is only used for encryption. */
85 static CipherContext send_context;
87 /* Buffer for raw input data from the socket. */
90 /* Buffer for raw output data going to the socket. */
93 /* Buffer for the partial outgoing packet being constructed. */
94 static Buffer outgoing_packet;
96 /* Buffer for the incoming packet currently being processed. */
97 static Buffer incoming_packet;
99 /* Scratch buffer for packet compression/decompression. */
100 static Buffer compression_buffer;
101 static int compression_buffer_ready = 0;
103 /* Flag indicating whether packet compression/decompression is enabled. */
104 static int packet_compression = 0;
106 /* default maximum packet size */
107 int max_packet_size = 32768;
109 /* Flag indicating whether this module has been initialized. */
110 static int initialized = 0;
112 /* Set to true if the connection is interactive. */
113 static int interactive_mode = 0;
115 /* Session key information for Encryption and MAC */
116 Newkeys *newkeys[MODE_MAX];
119 * Sets the descriptors used for communication. Disables encryption until
120 * packet_set_encryption_key is called.
123 packet_set_connection(int fd_in, int fd_out)
125 Cipher *none = cipher_by_name("none");
127 fatal("packet_set_connection: cannot load cipher 'none'");
128 connection_in = fd_in;
129 connection_out = fd_out;
130 cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0);
131 cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0);
132 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
136 buffer_init(&output);
137 buffer_init(&outgoing_packet);
138 buffer_init(&incoming_packet);
140 /* Kludge: arrange the close function to be called from fatal(). */
141 fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
144 /* Returns 1 if remote host is connected via socket, 0 if not. */
147 packet_connection_is_on_socket()
149 struct sockaddr_storage from, to;
150 socklen_t fromlen, tolen;
152 /* filedescriptors in and out are the same, so it's a socket */
153 if (connection_in == connection_out)
155 fromlen = sizeof(from);
156 memset(&from, 0, sizeof(from));
157 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
160 memset(&to, 0, sizeof(to));
161 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
163 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
165 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
170 /* returns 1 if connection is via ipv4 */
173 packet_connection_is_ipv4()
175 struct sockaddr_storage to;
176 socklen_t tolen = sizeof(to);
178 memset(&to, 0, sizeof(to));
179 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
181 if (to.ss_family != AF_INET)
186 /* Sets the connection into non-blocking mode. */
189 packet_set_nonblocking()
191 /* Set the socket into non-blocking mode. */
192 if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
193 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
195 if (connection_out != connection_in) {
196 if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
197 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
201 /* Returns the socket used for reading. */
204 packet_get_connection_in()
206 return connection_in;
209 /* Returns the descriptor used for writing. */
212 packet_get_connection_out()
214 return connection_out;
217 /* Closes the connection and clears and frees internal data structures. */
225 if (connection_in == connection_out) {
226 shutdown(connection_out, SHUT_RDWR);
227 close(connection_out);
229 close(connection_in);
230 close(connection_out);
233 buffer_free(&output);
234 buffer_free(&outgoing_packet);
235 buffer_free(&incoming_packet);
236 if (compression_buffer_ready) {
237 buffer_free(&compression_buffer);
238 buffer_compress_uninit();
242 /* Sets remote side protocol flags. */
245 packet_set_protocol_flags(u_int protocol_flags)
247 remote_protocol_flags = protocol_flags;
250 /* Returns the remote protocol flags set earlier by the above function. */
253 packet_get_protocol_flags()
255 return remote_protocol_flags;
259 * Starts packet compression from the next packet on in both directions.
260 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
264 packet_init_compression()
266 if (compression_buffer_ready == 1)
268 compression_buffer_ready = 1;
269 buffer_init(&compression_buffer);
273 packet_start_compression(int level)
275 if (packet_compression && !compat20)
276 fatal("Compression already enabled.");
277 packet_compression = 1;
278 packet_init_compression();
279 buffer_compress_init_send(level);
280 buffer_compress_init_recv();
284 * Causes any further packets to be encrypted using the given key. The same
285 * key is used for both sending and reception. However, both directions are
286 * encrypted independently of each other.
289 packet_set_encryption_key(const u_char *key, u_int keylen,
292 Cipher *cipher = cipher_by_number(number);
294 fatal("packet_set_encryption_key: unknown cipher number %d", number);
296 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
297 cipher_init(&receive_context, cipher, key, keylen, NULL, 0);
298 cipher_init(&send_context, cipher, key, keylen, NULL, 0);
301 /* Start constructing a packet to send. */
303 packet_start(u_char type)
308 DBG(debug("packet_start[%d]", type));
309 len = compat20 ? 6 : 9;
310 memset(buf, 0, len - 1);
312 buffer_clear(&outgoing_packet);
313 buffer_append(&outgoing_packet, buf, len);
316 /* Append payload. */
318 packet_put_char(int value)
321 buffer_append(&outgoing_packet, &ch, 1);
324 packet_put_int(u_int value)
326 buffer_put_int(&outgoing_packet, value);
329 packet_put_string(const char *buf, u_int len)
331 buffer_put_string(&outgoing_packet, buf, len);
334 packet_put_cstring(const char *str)
336 buffer_put_cstring(&outgoing_packet, str);
339 packet_put_raw(const char *buf, u_int len)
341 buffer_append(&outgoing_packet, buf, len);
344 packet_put_bignum(BIGNUM * value)
346 buffer_put_bignum(&outgoing_packet, value);
349 packet_put_bignum2(BIGNUM * value)
351 buffer_put_bignum2(&outgoing_packet, value);
355 * Finalizes and sends the packet. If the encryption key has been set,
356 * encrypts the packet before sending.
368 * If using packet compression, compress the payload of the outgoing
371 if (packet_compression) {
372 buffer_clear(&compression_buffer);
374 buffer_consume(&outgoing_packet, 8);
376 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
377 buffer_compress(&outgoing_packet, &compression_buffer);
378 buffer_clear(&outgoing_packet);
379 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
380 buffer_len(&compression_buffer));
382 /* Compute packet length without padding (add checksum, remove padding). */
383 len = buffer_len(&outgoing_packet) + 4 - 8;
385 /* Insert padding. Initialized to zero in packet_start1() */
386 padding = 8 - len % 8;
387 if (send_context.cipher->number != SSH_CIPHER_NONE) {
388 cp = buffer_ptr(&outgoing_packet);
389 for (i = 0; i < padding; i++) {
392 cp[7 - i] = rand & 0xff;
396 buffer_consume(&outgoing_packet, 8 - padding);
398 /* Add check bytes. */
399 checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet),
400 buffer_len(&outgoing_packet));
401 PUT_32BIT(buf, checksum);
402 buffer_append(&outgoing_packet, buf, 4);
405 fprintf(stderr, "packet_send plain: ");
406 buffer_dump(&outgoing_packet);
409 /* Append to output. */
411 buffer_append(&output, buf, 4);
412 buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
413 cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
414 buffer_len(&outgoing_packet));
417 fprintf(stderr, "encrypted: ");
418 buffer_dump(&output);
421 buffer_clear(&outgoing_packet);
424 * Note that the packet is now only buffered in output. It won\'t be
425 * actually sent until packet_write_wait or packet_write_poll is
431 set_newkeys(int mode)
438 debug("newkeys: mode %d", mode);
440 cc = (mode == MODE_OUT) ? &send_context : &receive_context;
441 if (newkeys[mode] != NULL) {
442 debug("newkeys: rekeying");
443 /* todo: free old keys, reset compression/cipher-ctxt; */
444 memset(cc, 0, sizeof(*cc));
445 enc = &newkeys[mode]->enc;
446 mac = &newkeys[mode]->mac;
447 comp = &newkeys[mode]->comp;
448 memset(mac->key, 0, mac->key_len);
455 xfree(newkeys[mode]);
457 newkeys[mode] = kex_get_newkeys(mode);
458 if (newkeys[mode] == NULL)
459 fatal("newkeys: no keys for mode %d", mode);
460 enc = &newkeys[mode]->enc;
461 mac = &newkeys[mode]->mac;
462 comp = &newkeys[mode]->comp;
465 DBG(debug("cipher_init_context: %d", mode));
466 cipher_init(cc, enc->cipher, enc->key, enc->cipher->key_len,
467 enc->iv, enc->cipher->block_size);
468 memset(enc->iv, 0, enc->cipher->block_size);
469 memset(enc->key, 0, enc->cipher->key_len);
470 if (comp->type != 0 && comp->enabled == 0) {
471 packet_init_compression();
472 if (mode == MODE_OUT)
473 buffer_compress_init_send(6);
475 buffer_compress_init_recv();
481 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
486 static u_int32_t seqnr = 0;
487 u_char type, *ucp, *macbuf = NULL;
489 u_int packet_length = 0;
490 u_int i, padlen, len;
497 if (newkeys[MODE_OUT] != NULL) {
498 enc = &newkeys[MODE_OUT]->enc;
499 mac = &newkeys[MODE_OUT]->mac;
500 comp = &newkeys[MODE_OUT]->comp;
502 block_size = enc ? enc->cipher->block_size : 8;
504 ucp = (u_char *) buffer_ptr(&outgoing_packet);
508 fprintf(stderr, "plain: ");
509 buffer_dump(&outgoing_packet);
512 if (comp && comp->enabled) {
513 len = buffer_len(&outgoing_packet);
514 /* skip header, compress only payload */
515 buffer_consume(&outgoing_packet, 5);
516 buffer_clear(&compression_buffer);
517 buffer_compress(&outgoing_packet, &compression_buffer);
518 buffer_clear(&outgoing_packet);
519 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
520 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
521 buffer_len(&compression_buffer));
522 DBG(debug("compression: raw %d compressed %d", len,
523 buffer_len(&outgoing_packet)));
526 /* sizeof (packet_len + pad_len + payload) */
527 len = buffer_len(&outgoing_packet);
530 * calc size of padding, alloc space, get random data,
531 * minimum padding is 4 bytes
533 padlen = block_size - (len % block_size);
535 padlen += block_size;
536 buffer_append_space(&outgoing_packet, &cp, padlen);
537 if (enc && enc->cipher->number != SSH_CIPHER_NONE) {
539 for (i = 0; i < padlen; i++) {
547 memset(cp, 0, padlen);
549 /* packet_length includes payload, padding and padding length field */
550 packet_length = buffer_len(&outgoing_packet) - 4;
551 ucp = (u_char *)buffer_ptr(&outgoing_packet);
552 PUT_32BIT(ucp, packet_length);
554 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
556 /* compute MAC over seqnr and packet(length fields, payload, padding) */
557 if (mac && mac->enabled) {
558 macbuf = mac_compute(mac, seqnr,
559 (u_char *) buffer_ptr(&outgoing_packet),
560 buffer_len(&outgoing_packet));
561 DBG(debug("done calc MAC out #%d", seqnr));
563 /* encrypt packet and append to output buffer. */
564 buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
565 cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
566 buffer_len(&outgoing_packet));
567 /* append unencrypted MAC */
568 if (mac && mac->enabled)
569 buffer_append(&output, (char *)macbuf, mac->mac_len);
571 fprintf(stderr, "encrypted: ");
572 buffer_dump(&output);
574 /* increment sequence number for outgoing packets */
576 log("outgoing seqnr wraps around");
577 buffer_clear(&outgoing_packet);
579 if (type == SSH2_MSG_NEWKEYS)
580 set_newkeys(MODE_OUT);
590 DBG(debug("packet_send done"));
594 * Waits until a packet has been received, and returns its type. Note that
595 * no other data is processed until this returns, so this function should not
596 * be used during the interactive session.
600 packet_read(int *payload_len_ptr)
605 DBG(debug("packet_read()"));
607 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) *
610 /* Since we are blocking, ensure that all written packets have been sent. */
613 /* Stay in the loop until we have received a complete packet. */
615 /* Try to read a packet from the buffer. */
616 type = packet_read_poll(payload_len_ptr);
618 type == SSH_SMSG_SUCCESS
619 || type == SSH_SMSG_FAILURE
620 || type == SSH_CMSG_EOF
621 || type == SSH_CMSG_EXIT_CONFIRMATION))
622 packet_integrity_check(*payload_len_ptr, 0, type);
623 /* If we got a packet, return it. */
624 if (type != SSH_MSG_NONE) {
629 * Otherwise, wait for some data to arrive, add it to the
630 * buffer, and try again.
632 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
634 FD_SET(connection_in, setp);
636 /* Wait for some data to arrive. */
637 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
638 (errno == EAGAIN || errno == EINTR))
641 /* Read data from the socket. */
642 len = read(connection_in, buf, sizeof(buf));
644 log("Connection closed by %.200s", get_remote_ipaddr());
648 fatal("Read from socket failed: %.100s", strerror(errno));
649 /* Append it to the buffer. */
650 packet_process_incoming(buf, len);
656 * Waits until a packet has been received, verifies that its type matches
657 * that given, and gives a fatal error and exits if there is a mismatch.
661 packet_read_expect(int *payload_len_ptr, int expected_type)
665 type = packet_read(payload_len_ptr);
666 if (type != expected_type)
667 packet_disconnect("Protocol error: expected packet type %d, got %d",
668 expected_type, type);
671 /* Checks if a full packet is available in the data received so far via
672 * packet_process_incoming. If so, reads the packet; otherwise returns
673 * SSH_MSG_NONE. This does not wait for data from the connection.
675 * SSH_MSG_DISCONNECT is handled specially here. Also,
676 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
679 * The returned payload_len does include space consumed by:
687 packet_read_poll1(int *payload_len_ptr)
689 u_int len, padded_len;
692 u_int checksum, stored_checksum;
694 /* Check if input size is less than minimum packet size. */
695 if (buffer_len(&input) < 4 + 8)
697 /* Get length of incoming packet. */
698 ucp = (u_char *) buffer_ptr(&input);
699 len = GET_32BIT(ucp);
700 if (len < 1 + 2 + 2 || len > 256 * 1024)
701 packet_disconnect("Bad packet length %d.", len);
702 padded_len = (len + 8) & ~7;
704 /* Check if the packet has been entirely received. */
705 if (buffer_len(&input) < 4 + padded_len)
708 /* The entire packet is in buffer. */
710 /* Consume packet length. */
711 buffer_consume(&input, 4);
714 * Cryptographic attack detector for ssh
715 * (C)1998 CORE-SDI, Buenos Aires Argentina
716 * Ariel Futoransky(futo@core-sdi.com)
718 if (receive_context.cipher->number != SSH_CIPHER_NONE &&
719 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED)
720 packet_disconnect("crc32 compensation attack: network attack detected");
722 /* Decrypt data to incoming_packet. */
723 buffer_clear(&incoming_packet);
724 buffer_append_space(&incoming_packet, &cp, padded_len);
725 cipher_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
727 buffer_consume(&input, padded_len);
730 fprintf(stderr, "read_poll plain: ");
731 buffer_dump(&incoming_packet);
734 /* Compute packet checksum. */
735 checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet),
736 buffer_len(&incoming_packet) - 4);
739 buffer_consume(&incoming_packet, 8 - len % 8);
741 /* Test check bytes. */
742 if (len != buffer_len(&incoming_packet))
743 packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
744 len, buffer_len(&incoming_packet));
746 ucp = (u_char *) buffer_ptr(&incoming_packet) + len - 4;
747 stored_checksum = GET_32BIT(ucp);
748 if (checksum != stored_checksum)
749 packet_disconnect("Corrupted check bytes on input.");
750 buffer_consume_end(&incoming_packet, 4);
752 if (packet_compression) {
753 buffer_clear(&compression_buffer);
754 buffer_uncompress(&incoming_packet, &compression_buffer);
755 buffer_clear(&incoming_packet);
756 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
757 buffer_len(&compression_buffer));
759 type = buffer_get_char(&incoming_packet);
760 *payload_len_ptr = buffer_len(&incoming_packet);
765 packet_read_poll2(int *payload_len_ptr)
767 static u_int32_t seqnr = 0;
768 static u_int packet_length = 0;
770 u_char *macbuf, *ucp, type;
772 int maclen, block_size;
777 if (newkeys[MODE_IN] != NULL) {
778 enc = &newkeys[MODE_IN]->enc;
779 mac = &newkeys[MODE_IN]->mac;
780 comp = &newkeys[MODE_IN]->comp;
782 maclen = mac && mac->enabled ? mac->mac_len : 0;
783 block_size = enc ? enc->cipher->block_size : 8;
785 if (packet_length == 0) {
787 * check if input size is less than the cipher block size,
788 * decrypt first block and extract length of incoming packet
790 if (buffer_len(&input) < block_size)
792 buffer_clear(&incoming_packet);
793 buffer_append_space(&incoming_packet, &cp, block_size);
794 cipher_decrypt(&receive_context, cp, buffer_ptr(&input),
796 ucp = (u_char *) buffer_ptr(&incoming_packet);
797 packet_length = GET_32BIT(ucp);
798 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
799 buffer_dump(&incoming_packet);
800 packet_disconnect("Bad packet length %d.", packet_length);
802 DBG(debug("input: packet len %d", packet_length+4));
803 buffer_consume(&input, block_size);
805 /* we have a partial packet of block_size bytes */
806 need = 4 + packet_length - block_size;
807 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
809 if (need % block_size != 0)
810 fatal("padding error: need %d block %d mod %d",
811 need, block_size, need % block_size);
813 * check if the entire packet has been received and
814 * decrypt into incoming_packet
816 if (buffer_len(&input) < need + maclen)
819 fprintf(stderr, "read_poll enc/full: ");
822 buffer_append_space(&incoming_packet, &cp, need);
823 cipher_decrypt(&receive_context, cp, buffer_ptr(&input), need);
824 buffer_consume(&input, need);
826 * compute MAC over seqnr and packet,
827 * increment sequence number for incoming packet
829 if (mac && mac->enabled) {
830 macbuf = mac_compute(mac, seqnr,
831 (u_char *) buffer_ptr(&incoming_packet),
832 buffer_len(&incoming_packet));
833 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
834 packet_disconnect("Corrupted MAC on input.");
835 DBG(debug("MAC #%d ok", seqnr));
836 buffer_consume(&input, mac->mac_len);
839 log("incoming seqnr wraps around");
842 cp = buffer_ptr(&incoming_packet) + 4;
843 padlen = (u_char) *cp;
844 DBG(debug("input: padlen %d", padlen));
846 packet_disconnect("Corrupted padlen %d on input.", padlen);
848 /* skip packet size + padlen, discard padding */
849 buffer_consume(&incoming_packet, 4 + 1);
850 buffer_consume_end(&incoming_packet, padlen);
852 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
853 if (comp && comp->enabled) {
854 buffer_clear(&compression_buffer);
855 buffer_uncompress(&incoming_packet, &compression_buffer);
856 buffer_clear(&incoming_packet);
857 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
858 buffer_len(&compression_buffer));
859 DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
862 * get packet type, implies consume.
863 * return length of payload (without type field)
865 type = buffer_get_char(&incoming_packet);
866 if (type == SSH2_MSG_NEWKEYS)
867 set_newkeys(MODE_IN);
868 *payload_len_ptr = buffer_len(&incoming_packet);
870 fprintf(stderr, "read/plain[%d]:\r\n", type);
871 buffer_dump(&incoming_packet);
873 /* reset for next packet */
879 packet_read_poll(int *payload_len_ptr)
887 type = packet_read_poll2(payload_len_ptr);
889 DBG(debug("received packet type %d", type));
891 case SSH2_MSG_IGNORE:
895 msg = packet_get_string(NULL);
896 debug("Remote: %.900s", msg);
898 msg = packet_get_string(NULL);
901 case SSH2_MSG_DISCONNECT:
902 reason = packet_get_int();
903 msg = packet_get_string(NULL);
904 log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(),
914 type = packet_read_poll1(payload_len_ptr);
919 msg = packet_get_string(NULL);
920 debug("Remote: %.900s", msg);
923 case SSH_MSG_DISCONNECT:
924 msg = packet_get_string(NULL);
925 log("Received disconnect from %s: %.400s", get_remote_ipaddr(),
932 DBG(debug("received packet type %d", type));
941 * Buffers the given amount of input characters. This is intended to be used
942 * together with packet_read_poll.
946 packet_process_incoming(const char *buf, u_int len)
948 buffer_append(&input, buf, len);
951 /* Returns a character from the packet. */
957 buffer_get(&incoming_packet, &ch, 1);
961 /* Returns an integer from the packet data. */
966 return buffer_get_int(&incoming_packet);
970 * Returns an arbitrary precision integer from the packet data. The integer
971 * must have been initialized before this call.
975 packet_get_bignum(BIGNUM * value, int *length_ptr)
977 *length_ptr = buffer_get_bignum(&incoming_packet, value);
981 packet_get_bignum2(BIGNUM * value, int *length_ptr)
983 *length_ptr = buffer_get_bignum2(&incoming_packet, value);
987 packet_get_raw(int *length_ptr)
989 int bytes = buffer_len(&incoming_packet);
990 if (length_ptr != NULL)
992 return buffer_ptr(&incoming_packet);
996 packet_remaining(void)
998 return buffer_len(&incoming_packet);
1002 * Returns a string from the packet data. The string is allocated using
1003 * xmalloc; it is the responsibility of the calling program to free it when
1004 * no longer needed. The length_ptr argument may be NULL, or point to an
1005 * integer into which the length of the string is stored.
1009 packet_get_string(u_int *length_ptr)
1011 return buffer_get_string(&incoming_packet, length_ptr);
1015 * Sends a diagnostic message from the server to the client. This message
1016 * can be sent at any time (but not while constructing another message). The
1017 * message is printed immediately, but only if the client is being executed
1018 * in verbose mode. These messages are primarily intended to ease debugging
1019 * authentication problems. The length of the formatted message must not
1020 * exceed 1024 bytes. This will automatically call packet_write_wait.
1024 packet_send_debug(const char *fmt,...)
1029 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1032 va_start(args, fmt);
1033 vsnprintf(buf, sizeof(buf), fmt, args);
1037 packet_start(SSH2_MSG_DEBUG);
1038 packet_put_char(0); /* bool: always display */
1039 packet_put_cstring(buf);
1040 packet_put_cstring("");
1042 packet_start(SSH_MSG_DEBUG);
1043 packet_put_cstring(buf);
1046 packet_write_wait();
1050 * Logs the error plus constructs and sends a disconnect packet, closes the
1051 * connection, and exits. This function never returns. The error message
1052 * should not contain a newline. The length of the formatted message must
1053 * not exceed 1024 bytes.
1057 packet_disconnect(const char *fmt,...)
1061 static int disconnecting = 0;
1062 if (disconnecting) /* Guard against recursive invocations. */
1063 fatal("packet_disconnect called recursively.");
1067 * Format the message. Note that the caller must make sure the
1068 * message is of limited size.
1070 va_start(args, fmt);
1071 vsnprintf(buf, sizeof(buf), fmt, args);
1074 /* Send the disconnect message to the other side, and wait for it to get sent. */
1076 packet_start(SSH2_MSG_DISCONNECT);
1077 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1078 packet_put_cstring(buf);
1079 packet_put_cstring("");
1081 packet_start(SSH_MSG_DISCONNECT);
1082 packet_put_cstring(buf);
1085 packet_write_wait();
1087 /* Stop listening for connections. */
1088 channel_stop_listening();
1090 /* Close the connection. */
1093 /* Display the error locally and exit. */
1094 log("Disconnecting: %.100s", buf);
1098 /* Checks if there is any buffered output, and tries to write some of the output. */
1103 int len = buffer_len(&output);
1105 len = write(connection_out, buffer_ptr(&output), len);
1107 if (errno == EAGAIN)
1110 fatal("Write failed: %.100s", strerror(errno));
1112 buffer_consume(&output, len);
1117 * Calls packet_write_poll repeatedly until all pending output data has been
1126 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) *
1128 packet_write_poll();
1129 while (packet_have_data_to_write()) {
1130 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1132 FD_SET(connection_out, setp);
1133 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1134 (errno == EAGAIN || errno == EINTR))
1136 packet_write_poll();
1141 /* Returns true if there is buffered data to write to the connection. */
1144 packet_have_data_to_write()
1146 return buffer_len(&output) != 0;
1149 /* Returns true if there is not too much data to write to the connection. */
1152 packet_not_very_much_data_to_write()
1154 if (interactive_mode)
1155 return buffer_len(&output) < 16384;
1157 return buffer_len(&output) < 128 * 1024;
1160 /* Informs that the current session is interactive. Sets IP flags for that. */
1163 packet_set_interactive(int interactive)
1165 static int called = 0;
1166 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1167 int lowdelay = IPTOS_LOWDELAY;
1168 int throughput = IPTOS_THROUGHPUT;
1176 /* Record that we are in interactive mode. */
1177 interactive_mode = interactive;
1179 /* Only set socket options if using a socket. */
1180 if (!packet_connection_is_on_socket())
1183 * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only
1187 * Set IP options for an interactive connection. Use
1188 * IPTOS_LOWDELAY and TCP_NODELAY.
1190 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1191 if (packet_connection_is_ipv4()) {
1192 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS,
1193 (void *) &lowdelay, sizeof(lowdelay)) < 0)
1194 error("setsockopt IPTOS_LOWDELAY: %.100s",
1198 if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on,
1200 error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
1201 } else if (packet_connection_is_ipv4()) {
1203 * Set IP options for a non-interactive connection. Use
1206 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1207 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput,
1208 sizeof(throughput)) < 0)
1209 error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1214 /* Returns true if the current connection is interactive. */
1217 packet_is_interactive()
1219 return interactive_mode;
1223 packet_set_maxsize(int s)
1225 static int called = 0;
1227 log("packet_set_maxsize: called twice: old %d new %d",
1228 max_packet_size, s);
1231 if (s < 4 * 1024 || s > 1024 * 1024) {
1232 log("packet_set_maxsize: bad size %d", s);
1235 log("packet_set_maxsize: setting to %d", s);
1236 max_packet_size = s;
1241 * 9.2. Ignored Data Message
1243 * byte SSH_MSG_IGNORE
1246 * All implementations MUST understand (and ignore) this message at any
1247 * time (after receiving the protocol version). No implementation is
1248 * required to send them. This message can be used as an additional
1249 * protection measure against advanced traffic analysis techniques.
1251 /* size of current + ignore message should be n*sumlen bytes (w/o mac) */
1253 packet_inject_ignore(int sumlen)
1255 int blocksize, padlen, have, need, nb, mini, nbytes;
1261 have = buffer_len(&outgoing_packet);
1262 debug2("packet_inject_ignore: current %d", have);
1263 if (newkeys[MODE_OUT] != NULL)
1264 enc = &newkeys[MODE_OUT]->enc;
1265 blocksize = enc ? enc->cipher->block_size : 8;
1266 padlen = blocksize - (have % blocksize);
1268 padlen += blocksize;
1270 have /= blocksize; /* # of blocks for current message */
1272 nb = roundup(sumlen, blocksize) / blocksize; /* blocks for both */
1273 mini = roundup(5+1+4+4, blocksize) / blocksize; /* minsize ignore msg */
1274 need = nb - (have % nb); /* blocks for ignore */
1277 nbytes = (need - mini) * blocksize; /* size of ignore payload */
1278 debug2("packet_inject_ignore: block %d have %d nb %d mini %d need %d",
1279 blocksize, have, nb, mini, need);
1281 /* enqueue current message and append a ignore message */
1283 packet_send_ignore(nbytes);
1287 packet_send_ignore(int nbytes)
1292 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1293 packet_put_int(nbytes);
1294 for(i = 0; i < nbytes; i++) {
1296 rand = arc4random();
1297 packet_put_char(rand & 0xff);