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 1.90 2002/02/27 21:23:13 stevesk Exp $");
71 * This variable contains the file descriptors used for communicating with
72 * the other side. connection_in is used for reading; connection_out for
73 * writing. These can be the same descriptor, in which case it is assumed to
76 static int connection_in = -1;
77 static int connection_out = -1;
79 /* Protocol flags for the remote side. */
80 static u_int remote_protocol_flags = 0;
82 /* Encryption context for receiving data. This is only used for decryption. */
83 static CipherContext receive_context;
85 /* Encryption context for sending data. This is only used for encryption. */
86 static CipherContext send_context;
88 /* Buffer for raw input data from the socket. */
91 /* Buffer for raw output data going to the socket. */
94 /* Buffer for the partial outgoing packet being constructed. */
95 static Buffer outgoing_packet;
97 /* Buffer for the incoming packet currently being processed. */
98 static Buffer incoming_packet;
100 /* Scratch buffer for packet compression/decompression. */
101 static Buffer compression_buffer;
102 static int compression_buffer_ready = 0;
104 /* Flag indicating whether packet compression/decompression is enabled. */
105 static int packet_compression = 0;
107 /* default maximum packet size */
108 int max_packet_size = 32768;
110 /* Flag indicating whether this module has been initialized. */
111 static int initialized = 0;
113 /* Set to true if the connection is interactive. */
114 static int interactive_mode = 0;
116 /* Session key information for Encryption and MAC */
117 Newkeys *newkeys[MODE_MAX];
119 /* roundup current message to extra_pad bytes */
120 static u_char extra_pad = 0;
123 * Sets the descriptors used for communication. Disables encryption until
124 * packet_set_encryption_key is called.
127 packet_set_connection(int fd_in, int fd_out)
129 Cipher *none = cipher_by_name("none");
131 fatal("packet_set_connection: cannot load cipher 'none'");
132 connection_in = fd_in;
133 connection_out = fd_out;
134 cipher_init(&send_context, none, "", 0, NULL, 0, CIPHER_ENCRYPT);
135 cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT);
136 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
140 buffer_init(&output);
141 buffer_init(&outgoing_packet);
142 buffer_init(&incoming_packet);
144 /* Kludge: arrange the close function to be called from fatal(). */
145 fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
148 /* Returns 1 if remote host is connected via socket, 0 if not. */
151 packet_connection_is_on_socket(void)
153 struct sockaddr_storage from, to;
154 socklen_t fromlen, tolen;
156 /* filedescriptors in and out are the same, so it's a socket */
157 if (connection_in == connection_out)
159 fromlen = sizeof(from);
160 memset(&from, 0, sizeof(from));
161 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
164 memset(&to, 0, sizeof(to));
165 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
167 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
169 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
174 /* returns 1 if connection is via ipv4 */
177 packet_connection_is_ipv4(void)
179 struct sockaddr_storage to;
180 socklen_t tolen = sizeof(to);
182 memset(&to, 0, sizeof(to));
183 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
185 if (to.ss_family != AF_INET)
190 /* Sets the connection into non-blocking mode. */
193 packet_set_nonblocking(void)
195 /* Set the socket into non-blocking mode. */
196 if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
197 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
199 if (connection_out != connection_in) {
200 if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
201 error("fcntl O_NONBLOCK: %.100s", strerror(errno));
205 /* Returns the socket used for reading. */
208 packet_get_connection_in(void)
210 return connection_in;
213 /* Returns the descriptor used for writing. */
216 packet_get_connection_out(void)
218 return connection_out;
221 /* Closes the connection and clears and frees internal data structures. */
229 if (connection_in == connection_out) {
230 shutdown(connection_out, SHUT_RDWR);
231 close(connection_out);
233 close(connection_in);
234 close(connection_out);
237 buffer_free(&output);
238 buffer_free(&outgoing_packet);
239 buffer_free(&incoming_packet);
240 if (compression_buffer_ready) {
241 buffer_free(&compression_buffer);
242 buffer_compress_uninit();
244 cipher_cleanup(&send_context);
245 cipher_cleanup(&receive_context);
248 /* Sets remote side protocol flags. */
251 packet_set_protocol_flags(u_int protocol_flags)
253 remote_protocol_flags = protocol_flags;
256 /* Returns the remote protocol flags set earlier by the above function. */
259 packet_get_protocol_flags(void)
261 return remote_protocol_flags;
265 * Starts packet compression from the next packet on in both directions.
266 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
270 packet_init_compression(void)
272 if (compression_buffer_ready == 1)
274 compression_buffer_ready = 1;
275 buffer_init(&compression_buffer);
279 packet_start_compression(int level)
281 if (packet_compression && !compat20)
282 fatal("Compression already enabled.");
283 packet_compression = 1;
284 packet_init_compression();
285 buffer_compress_init_send(level);
286 buffer_compress_init_recv();
290 * Causes any further packets to be encrypted using the given key. The same
291 * key is used for both sending and reception. However, both directions are
292 * encrypted independently of each other.
295 packet_set_encryption_key(const u_char *key, u_int keylen,
298 Cipher *cipher = cipher_by_number(number);
300 fatal("packet_set_encryption_key: unknown cipher number %d", number);
302 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
303 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
304 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
307 /* Start constructing a packet to send. */
309 packet_start(u_char type)
314 DBG(debug("packet_start[%d]", type));
315 len = compat20 ? 6 : 9;
316 memset(buf, 0, len - 1);
318 buffer_clear(&outgoing_packet);
319 buffer_append(&outgoing_packet, buf, len);
322 /* Append payload. */
324 packet_put_char(int value)
327 buffer_append(&outgoing_packet, &ch, 1);
330 packet_put_int(u_int value)
332 buffer_put_int(&outgoing_packet, value);
335 packet_put_string(const void *buf, u_int len)
337 buffer_put_string(&outgoing_packet, buf, len);
340 packet_put_cstring(const char *str)
342 buffer_put_cstring(&outgoing_packet, str);
345 packet_put_raw(const void *buf, u_int len)
347 buffer_append(&outgoing_packet, buf, len);
350 packet_put_bignum(BIGNUM * value)
352 buffer_put_bignum(&outgoing_packet, value);
355 packet_put_bignum2(BIGNUM * value)
357 buffer_put_bignum2(&outgoing_packet, value);
361 * Finalizes and sends the packet. If the encryption key has been set,
362 * encrypts the packet before sending.
374 * If using packet compression, compress the payload of the outgoing
377 if (packet_compression) {
378 buffer_clear(&compression_buffer);
380 buffer_consume(&outgoing_packet, 8);
382 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
383 buffer_compress(&outgoing_packet, &compression_buffer);
384 buffer_clear(&outgoing_packet);
385 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
386 buffer_len(&compression_buffer));
388 /* Compute packet length without padding (add checksum, remove padding). */
389 len = buffer_len(&outgoing_packet) + 4 - 8;
391 /* Insert padding. Initialized to zero in packet_start1() */
392 padding = 8 - len % 8;
393 if (!send_context.plaintext) {
394 cp = buffer_ptr(&outgoing_packet);
395 for (i = 0; i < padding; i++) {
398 cp[7 - i] = rand & 0xff;
402 buffer_consume(&outgoing_packet, 8 - padding);
404 /* Add check bytes. */
405 checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
406 buffer_len(&outgoing_packet));
407 PUT_32BIT(buf, checksum);
408 buffer_append(&outgoing_packet, buf, 4);
411 fprintf(stderr, "packet_send plain: ");
412 buffer_dump(&outgoing_packet);
415 /* Append to output. */
417 buffer_append(&output, buf, 4);
418 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
419 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
420 buffer_len(&outgoing_packet));
423 fprintf(stderr, "encrypted: ");
424 buffer_dump(&output);
427 buffer_clear(&outgoing_packet);
430 * Note that the packet is now only buffered in output. It won\'t be
431 * actually sent until packet_write_wait or packet_write_poll is
437 set_newkeys(int mode)
445 debug("newkeys: mode %d", mode);
447 if (mode == MODE_OUT) {
449 encrypt = CIPHER_ENCRYPT;
451 cc = &receive_context;
452 encrypt = CIPHER_DECRYPT;
454 if (newkeys[mode] != NULL) {
455 debug("newkeys: rekeying");
457 enc = &newkeys[mode]->enc;
458 mac = &newkeys[mode]->mac;
459 comp = &newkeys[mode]->comp;
460 memset(mac->key, 0, mac->key_len);
467 xfree(newkeys[mode]);
469 newkeys[mode] = kex_get_newkeys(mode);
470 if (newkeys[mode] == NULL)
471 fatal("newkeys: no keys for mode %d", mode);
472 enc = &newkeys[mode]->enc;
473 mac = &newkeys[mode]->mac;
474 comp = &newkeys[mode]->comp;
477 DBG(debug("cipher_init_context: %d", mode));
478 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
479 enc->iv, enc->block_size, encrypt);
480 memset(enc->iv, 0, enc->block_size);
481 memset(enc->key, 0, enc->key_len);
482 if (comp->type != 0 && comp->enabled == 0) {
483 packet_init_compression();
484 if (mode == MODE_OUT)
485 buffer_compress_init_send(6);
487 buffer_compress_init_recv();
493 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
498 static u_int32_t seqnr = 0;
499 u_char type, *cp, *macbuf = NULL;
501 u_int packet_length = 0;
509 if (newkeys[MODE_OUT] != NULL) {
510 enc = &newkeys[MODE_OUT]->enc;
511 mac = &newkeys[MODE_OUT]->mac;
512 comp = &newkeys[MODE_OUT]->comp;
514 block_size = enc ? enc->block_size : 8;
516 cp = buffer_ptr(&outgoing_packet);
520 fprintf(stderr, "plain: ");
521 buffer_dump(&outgoing_packet);
524 if (comp && comp->enabled) {
525 len = buffer_len(&outgoing_packet);
526 /* skip header, compress only payload */
527 buffer_consume(&outgoing_packet, 5);
528 buffer_clear(&compression_buffer);
529 buffer_compress(&outgoing_packet, &compression_buffer);
530 buffer_clear(&outgoing_packet);
531 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
532 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
533 buffer_len(&compression_buffer));
534 DBG(debug("compression: raw %d compressed %d", len,
535 buffer_len(&outgoing_packet)));
538 /* sizeof (packet_len + pad_len + payload) */
539 len = buffer_len(&outgoing_packet);
542 * calc size of padding, alloc space, get random data,
543 * minimum padding is 4 bytes
545 padlen = block_size - (len % block_size);
547 padlen += block_size;
549 /* will wrap if extra_pad+padlen > 255 */
550 extra_pad = roundup(extra_pad, block_size);
551 pad = extra_pad - ((len + padlen) % extra_pad);
552 debug("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
553 pad, len, padlen, extra_pad);
557 cp = buffer_append_space(&outgoing_packet, padlen);
558 if (enc && !send_context.plaintext) {
560 for (i = 0; i < padlen; i++) {
568 memset(cp, 0, padlen);
570 /* packet_length includes payload, padding and padding length field */
571 packet_length = buffer_len(&outgoing_packet) - 4;
572 cp = buffer_ptr(&outgoing_packet);
573 PUT_32BIT(cp, packet_length);
575 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
577 /* compute MAC over seqnr and packet(length fields, payload, padding) */
578 if (mac && mac->enabled) {
579 macbuf = mac_compute(mac, seqnr,
580 buffer_ptr(&outgoing_packet),
581 buffer_len(&outgoing_packet));
582 DBG(debug("done calc MAC out #%d", seqnr));
584 /* encrypt packet and append to output buffer. */
585 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
586 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
587 buffer_len(&outgoing_packet));
588 /* append unencrypted MAC */
589 if (mac && mac->enabled)
590 buffer_append(&output, (char *)macbuf, mac->mac_len);
592 fprintf(stderr, "encrypted: ");
593 buffer_dump(&output);
595 /* increment sequence number for outgoing packets */
597 log("outgoing seqnr wraps around");
598 buffer_clear(&outgoing_packet);
600 if (type == SSH2_MSG_NEWKEYS)
601 set_newkeys(MODE_OUT);
611 DBG(debug("packet_send done"));
615 * Waits until a packet has been received, and returns its type. Note that
616 * no other data is processed until this returns, so this function should not
617 * be used during the interactive session.
621 packet_read_seqnr(u_int32_t *seqnr_p)
626 DBG(debug("packet_read()"));
628 setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) *
631 /* Since we are blocking, ensure that all written packets have been sent. */
634 /* Stay in the loop until we have received a complete packet. */
636 /* Try to read a packet from the buffer. */
637 type = packet_read_poll_seqnr(seqnr_p);
639 type == SSH_SMSG_SUCCESS
640 || type == SSH_SMSG_FAILURE
641 || type == SSH_CMSG_EOF
642 || type == SSH_CMSG_EXIT_CONFIRMATION))
644 /* If we got a packet, return it. */
645 if (type != SSH_MSG_NONE) {
650 * Otherwise, wait for some data to arrive, add it to the
651 * buffer, and try again.
653 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
655 FD_SET(connection_in, setp);
657 /* Wait for some data to arrive. */
658 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
659 (errno == EAGAIN || errno == EINTR))
662 /* Read data from the socket. */
663 len = read(connection_in, buf, sizeof(buf));
665 log("Connection closed by %.200s", get_remote_ipaddr());
669 fatal("Read from socket failed: %.100s", strerror(errno));
670 /* Append it to the buffer. */
671 packet_process_incoming(buf, len);
679 return packet_read_seqnr(NULL);
683 * Waits until a packet has been received, verifies that its type matches
684 * that given, and gives a fatal error and exits if there is a mismatch.
688 packet_read_expect(int expected_type)
692 type = packet_read();
693 if (type != expected_type)
694 packet_disconnect("Protocol error: expected packet type %d, got %d",
695 expected_type, type);
698 /* Checks if a full packet is available in the data received so far via
699 * packet_process_incoming. If so, reads the packet; otherwise returns
700 * SSH_MSG_NONE. This does not wait for data from the connection.
702 * SSH_MSG_DISCONNECT is handled specially here. Also,
703 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
708 packet_read_poll1(void)
710 u_int len, padded_len;
712 u_int checksum, stored_checksum;
714 /* Check if input size is less than minimum packet size. */
715 if (buffer_len(&input) < 4 + 8)
717 /* Get length of incoming packet. */
718 cp = buffer_ptr(&input);
720 if (len < 1 + 2 + 2 || len > 256 * 1024)
721 packet_disconnect("Bad packet length %d.", len);
722 padded_len = (len + 8) & ~7;
724 /* Check if the packet has been entirely received. */
725 if (buffer_len(&input) < 4 + padded_len)
728 /* The entire packet is in buffer. */
730 /* Consume packet length. */
731 buffer_consume(&input, 4);
734 * Cryptographic attack detector for ssh
735 * (C)1998 CORE-SDI, Buenos Aires Argentina
736 * Ariel Futoransky(futo@core-sdi.com)
738 if (!receive_context.plaintext &&
739 detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED)
740 packet_disconnect("crc32 compensation attack: network attack detected");
742 /* Decrypt data to incoming_packet. */
743 buffer_clear(&incoming_packet);
744 cp = buffer_append_space(&incoming_packet, padded_len);
745 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
747 buffer_consume(&input, padded_len);
750 fprintf(stderr, "read_poll plain: ");
751 buffer_dump(&incoming_packet);
754 /* Compute packet checksum. */
755 checksum = ssh_crc32(buffer_ptr(&incoming_packet),
756 buffer_len(&incoming_packet) - 4);
759 buffer_consume(&incoming_packet, 8 - len % 8);
761 /* Test check bytes. */
762 if (len != buffer_len(&incoming_packet))
763 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
764 len, buffer_len(&incoming_packet));
766 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
767 stored_checksum = GET_32BIT(cp);
768 if (checksum != stored_checksum)
769 packet_disconnect("Corrupted check bytes on input.");
770 buffer_consume_end(&incoming_packet, 4);
772 if (packet_compression) {
773 buffer_clear(&compression_buffer);
774 buffer_uncompress(&incoming_packet, &compression_buffer);
775 buffer_clear(&incoming_packet);
776 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
777 buffer_len(&compression_buffer));
779 type = buffer_get_char(&incoming_packet);
784 packet_read_poll2(u_int32_t *seqnr_p)
786 static u_int32_t seqnr = 0;
787 static u_int packet_length = 0;
789 u_char *macbuf, *cp, type;
790 int maclen, block_size;
795 if (newkeys[MODE_IN] != NULL) {
796 enc = &newkeys[MODE_IN]->enc;
797 mac = &newkeys[MODE_IN]->mac;
798 comp = &newkeys[MODE_IN]->comp;
800 maclen = mac && mac->enabled ? mac->mac_len : 0;
801 block_size = enc ? enc->block_size : 8;
803 if (packet_length == 0) {
805 * check if input size is less than the cipher block size,
806 * decrypt first block and extract length of incoming packet
808 if (buffer_len(&input) < block_size)
810 buffer_clear(&incoming_packet);
811 cp = buffer_append_space(&incoming_packet, block_size);
812 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
814 cp = buffer_ptr(&incoming_packet);
815 packet_length = GET_32BIT(cp);
816 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
817 buffer_dump(&incoming_packet);
818 packet_disconnect("Bad packet length %d.", packet_length);
820 DBG(debug("input: packet len %d", packet_length+4));
821 buffer_consume(&input, block_size);
823 /* we have a partial packet of block_size bytes */
824 need = 4 + packet_length - block_size;
825 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
827 if (need % block_size != 0)
828 fatal("padding error: need %d block %d mod %d",
829 need, block_size, need % block_size);
831 * check if the entire packet has been received and
832 * decrypt into incoming_packet
834 if (buffer_len(&input) < need + maclen)
837 fprintf(stderr, "read_poll enc/full: ");
840 cp = buffer_append_space(&incoming_packet, need);
841 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
842 buffer_consume(&input, need);
844 * compute MAC over seqnr and packet,
845 * increment sequence number for incoming packet
847 if (mac && mac->enabled) {
848 macbuf = mac_compute(mac, seqnr,
849 buffer_ptr(&incoming_packet),
850 buffer_len(&incoming_packet));
851 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
852 packet_disconnect("Corrupted MAC on input.");
853 DBG(debug("MAC #%d ok", seqnr));
854 buffer_consume(&input, mac->mac_len);
859 log("incoming seqnr wraps around");
862 cp = buffer_ptr(&incoming_packet);
864 DBG(debug("input: padlen %d", padlen));
866 packet_disconnect("Corrupted padlen %d on input.", padlen);
868 /* skip packet size + padlen, discard padding */
869 buffer_consume(&incoming_packet, 4 + 1);
870 buffer_consume_end(&incoming_packet, padlen);
872 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
873 if (comp && comp->enabled) {
874 buffer_clear(&compression_buffer);
875 buffer_uncompress(&incoming_packet, &compression_buffer);
876 buffer_clear(&incoming_packet);
877 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
878 buffer_len(&compression_buffer));
879 DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
882 * get packet type, implies consume.
883 * return length of payload (without type field)
885 type = buffer_get_char(&incoming_packet);
886 if (type == SSH2_MSG_NEWKEYS)
887 set_newkeys(MODE_IN);
889 fprintf(stderr, "read/plain[%d]:\r\n", type);
890 buffer_dump(&incoming_packet);
892 /* reset for next packet */
898 packet_read_poll_seqnr(u_int32_t *seqnr_p)
906 type = packet_read_poll2(seqnr_p);
908 DBG(debug("received packet type %d", type));
910 case SSH2_MSG_IGNORE:
914 msg = packet_get_string(NULL);
915 debug("Remote: %.900s", msg);
917 msg = packet_get_string(NULL);
920 case SSH2_MSG_DISCONNECT:
921 reason = packet_get_int();
922 msg = packet_get_string(NULL);
923 log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(),
928 case SSH2_MSG_UNIMPLEMENTED:
929 seqnr = packet_get_int();
930 debug("Received SSH2_MSG_UNIMPLEMENTED for %d", seqnr);
937 type = packet_read_poll1();
942 msg = packet_get_string(NULL);
943 debug("Remote: %.900s", msg);
946 case SSH_MSG_DISCONNECT:
947 msg = packet_get_string(NULL);
948 log("Received disconnect from %s: %.400s", get_remote_ipaddr(),
955 DBG(debug("received packet type %d", type));
964 packet_read_poll(void)
966 return packet_read_poll_seqnr(NULL);
970 * Buffers the given amount of input characters. This is intended to be used
971 * together with packet_read_poll.
975 packet_process_incoming(const char *buf, u_int len)
977 buffer_append(&input, buf, len);
980 /* Returns a character from the packet. */
983 packet_get_char(void)
986 buffer_get(&incoming_packet, &ch, 1);
990 /* Returns an integer from the packet data. */
995 return buffer_get_int(&incoming_packet);
999 * Returns an arbitrary precision integer from the packet data. The integer
1000 * must have been initialized before this call.
1004 packet_get_bignum(BIGNUM * value)
1006 buffer_get_bignum(&incoming_packet, value);
1010 packet_get_bignum2(BIGNUM * value)
1012 buffer_get_bignum2(&incoming_packet, value);
1016 packet_get_raw(int *length_ptr)
1018 int bytes = buffer_len(&incoming_packet);
1019 if (length_ptr != NULL)
1020 *length_ptr = bytes;
1021 return buffer_ptr(&incoming_packet);
1025 packet_remaining(void)
1027 return buffer_len(&incoming_packet);
1031 * Returns a string from the packet data. The string is allocated using
1032 * xmalloc; it is the responsibility of the calling program to free it when
1033 * no longer needed. The length_ptr argument may be NULL, or point to an
1034 * integer into which the length of the string is stored.
1038 packet_get_string(u_int *length_ptr)
1040 return buffer_get_string(&incoming_packet, length_ptr);
1044 * Sends a diagnostic message from the server to the client. This message
1045 * can be sent at any time (but not while constructing another message). The
1046 * message is printed immediately, but only if the client is being executed
1047 * in verbose mode. These messages are primarily intended to ease debugging
1048 * authentication problems. The length of the formatted message must not
1049 * exceed 1024 bytes. This will automatically call packet_write_wait.
1053 packet_send_debug(const char *fmt,...)
1058 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1061 va_start(args, fmt);
1062 vsnprintf(buf, sizeof(buf), fmt, args);
1066 packet_start(SSH2_MSG_DEBUG);
1067 packet_put_char(0); /* bool: always display */
1068 packet_put_cstring(buf);
1069 packet_put_cstring("");
1071 packet_start(SSH_MSG_DEBUG);
1072 packet_put_cstring(buf);
1075 packet_write_wait();
1079 * Logs the error plus constructs and sends a disconnect packet, closes the
1080 * connection, and exits. This function never returns. The error message
1081 * should not contain a newline. The length of the formatted message must
1082 * not exceed 1024 bytes.
1086 packet_disconnect(const char *fmt,...)
1090 static int disconnecting = 0;
1091 if (disconnecting) /* Guard against recursive invocations. */
1092 fatal("packet_disconnect called recursively.");
1096 * Format the message. Note that the caller must make sure the
1097 * message is of limited size.
1099 va_start(args, fmt);
1100 vsnprintf(buf, sizeof(buf), fmt, args);
1103 /* Send the disconnect message to the other side, and wait for it to get sent. */
1105 packet_start(SSH2_MSG_DISCONNECT);
1106 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1107 packet_put_cstring(buf);
1108 packet_put_cstring("");
1110 packet_start(SSH_MSG_DISCONNECT);
1111 packet_put_cstring(buf);
1114 packet_write_wait();
1116 /* Stop listening for connections. */
1117 channel_close_all();
1119 /* Close the connection. */
1122 /* Display the error locally and exit. */
1123 log("Disconnecting: %.100s", buf);
1127 /* Checks if there is any buffered output, and tries to write some of the output. */
1130 packet_write_poll(void)
1132 int len = buffer_len(&output);
1134 len = write(connection_out, buffer_ptr(&output), len);
1136 if (errno == EAGAIN)
1139 fatal("Write failed: %.100s", strerror(errno));
1141 buffer_consume(&output, len);
1146 * Calls packet_write_poll repeatedly until all pending output data has been
1151 packet_write_wait(void)
1155 setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) *
1157 packet_write_poll();
1158 while (packet_have_data_to_write()) {
1159 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1161 FD_SET(connection_out, setp);
1162 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1163 (errno == EAGAIN || errno == EINTR))
1165 packet_write_poll();
1170 /* Returns true if there is buffered data to write to the connection. */
1173 packet_have_data_to_write(void)
1175 return buffer_len(&output) != 0;
1178 /* Returns true if there is not too much data to write to the connection. */
1181 packet_not_very_much_data_to_write(void)
1183 if (interactive_mode)
1184 return buffer_len(&output) < 16384;
1186 return buffer_len(&output) < 128 * 1024;
1189 /* Informs that the current session is interactive. Sets IP flags for that. */
1192 packet_set_interactive(int interactive)
1194 static int called = 0;
1195 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1196 int lowdelay = IPTOS_LOWDELAY;
1197 int throughput = IPTOS_THROUGHPUT;
1204 /* Record that we are in interactive mode. */
1205 interactive_mode = interactive;
1207 /* Only set socket options if using a socket. */
1208 if (!packet_connection_is_on_socket())
1211 * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only
1215 * Set IP options for an interactive connection. Use
1216 * IPTOS_LOWDELAY and TCP_NODELAY.
1218 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1219 if (packet_connection_is_ipv4()) {
1220 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS,
1221 &lowdelay, sizeof(lowdelay)) < 0)
1222 error("setsockopt IPTOS_LOWDELAY: %.100s",
1226 set_nodelay(connection_in);
1227 } else if (packet_connection_is_ipv4()) {
1229 * Set IP options for a non-interactive connection. Use
1232 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1233 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &throughput,
1234 sizeof(throughput)) < 0)
1235 error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1240 /* Returns true if the current connection is interactive. */
1243 packet_is_interactive(void)
1245 return interactive_mode;
1249 packet_set_maxsize(int s)
1251 static int called = 0;
1253 log("packet_set_maxsize: called twice: old %d new %d",
1254 max_packet_size, s);
1257 if (s < 4 * 1024 || s > 1024 * 1024) {
1258 log("packet_set_maxsize: bad size %d", s);
1262 debug("packet_set_maxsize: setting to %d", s);
1263 max_packet_size = s;
1267 /* roundup current message to pad bytes */
1269 packet_add_padding(u_char pad)
1275 * 9.2. Ignored Data Message
1277 * byte SSH_MSG_IGNORE
1280 * All implementations MUST understand (and ignore) this message at any
1281 * time (after receiving the protocol version). No implementation is
1282 * required to send them. This message can be used as an additional
1283 * protection measure against advanced traffic analysis techniques.
1286 packet_send_ignore(int nbytes)
1291 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1292 packet_put_int(nbytes);
1293 for (i = 0; i < nbytes; i++) {
1295 rand = arc4random();
1296 packet_put_char(rand & 0xff);