2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 RCSID("$OpenBSD: sshconnect2.c,v 1.30 2000/12/03 11:15:04 markus Exp $");
28 #include <openssl/bn.h>
29 #include <openssl/rsa.h>
30 #include <openssl/dsa.h>
31 #include <openssl/md5.h>
32 #include <openssl/dh.h>
33 #include <openssl/hmac.h>
46 #include "myproposal.h"
48 #include "sshconnect.h"
54 void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *);
55 void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *);
58 extern char *client_version_string;
59 extern char *server_version_string;
60 extern Options options;
66 unsigned char *session_id2 = NULL;
67 int session_id2_len = 0;
70 ssh_kex2(char *host, struct sockaddr *hostaddr)
74 Buffer *client_kexinit, *server_kexinit;
75 char *sprop[PROPOSAL_MAX];
77 if (options.ciphers == (char *)-1) {
78 log("No valid ciphers for protocol version 2 given, using defaults.");
79 options.ciphers = NULL;
81 if (options.ciphers != NULL) {
82 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
83 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
85 if (options.compression) {
86 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
87 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
89 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
90 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
93 /* buffers with raw kexinit messages */
94 server_kexinit = xmalloc(sizeof(*server_kexinit));
95 buffer_init(server_kexinit);
96 client_kexinit = kex_init(myproposal);
98 /* algorithm negotiation */
99 kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
100 kex = kex_choose_conf(myproposal, sprop, 0);
101 for (i = 0; i < PROPOSAL_MAX; i++)
104 /* server authentication and session key agreement */
105 switch(kex->kex_type) {
107 ssh_dh1_client(kex, host, hostaddr,
108 client_kexinit, server_kexinit);
111 ssh_dhgex_client(kex, host, hostaddr, client_kexinit,
115 fatal("Unsupported key exchange %d", kex->kex_type);
118 buffer_free(client_kexinit);
119 buffer_free(server_kexinit);
120 xfree(client_kexinit);
121 xfree(server_kexinit);
123 debug("Wait SSH2_MSG_NEWKEYS.");
124 packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
126 debug("GOT SSH2_MSG_NEWKEYS.");
128 debug("send SSH2_MSG_NEWKEYS.");
129 packet_start(SSH2_MSG_NEWKEYS);
132 debug("done: send SSH2_MSG_NEWKEYS.");
135 /* send 1st encrypted/maced/compressed message */
136 packet_start(SSH2_MSG_IGNORE);
137 packet_put_cstring("markus");
141 debug("done: KEX2.");
144 /* diffie-hellman-group1-sha1 */
147 ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr,
148 Buffer *client_kexinit, Buffer *server_kexinit)
154 unsigned int klen, kout;
155 char *signature = NULL;
157 char *server_host_key_blob = NULL;
158 Key *server_host_key;
159 unsigned int sbloblen;
161 BIGNUM *dh_server_pub = 0;
162 BIGNUM *shared_secret = 0;
166 debug("Sending SSH2_MSG_KEXDH_INIT.");
167 /* generate and send 'e', client DH public key */
168 dh = dh_new_group1();
169 packet_start(SSH2_MSG_KEXDH_INIT);
170 packet_put_bignum2(dh->pub_key);
175 fprintf(stderr, "\np= ");
176 BN_print_fp(stderr, dh->p);
177 fprintf(stderr, "\ng= ");
178 BN_print_fp(stderr, dh->g);
179 fprintf(stderr, "\npub= ");
180 BN_print_fp(stderr, dh->pub_key);
181 fprintf(stderr, "\n");
182 DHparams_print_fp(stderr, dh);
185 debug("Wait SSH2_MSG_KEXDH_REPLY.");
187 packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
189 debug("Got SSH2_MSG_KEXDH_REPLY.");
192 server_host_key_blob = packet_get_string(&sbloblen);
193 server_host_key = key_from_blob(server_host_key_blob, sbloblen);
194 if (server_host_key == NULL)
195 fatal("cannot decode server_host_key_blob");
197 check_host_key(host, hostaddr, server_host_key,
198 options.user_hostfile2, options.system_hostfile2);
200 /* DH paramter f, server public DH key */
201 dh_server_pub = BN_new();
202 if (dh_server_pub == NULL)
203 fatal("dh_server_pub == NULL");
204 packet_get_bignum2(dh_server_pub, &dlen);
207 fprintf(stderr, "\ndh_server_pub= ");
208 BN_print_fp(stderr, dh_server_pub);
209 fprintf(stderr, "\n");
210 debug("bits %d", BN_num_bits(dh_server_pub));
214 signature = packet_get_string(&slen);
217 if (!dh_pub_is_valid(dh, dh_server_pub))
218 packet_disconnect("bad server public DH value");
221 kbuf = xmalloc(klen);
222 kout = DH_compute_key(kbuf, dh_server_pub, dh);
224 debug("shared secret: len %d/%d", klen, kout);
225 fprintf(stderr, "shared secret == ");
226 for (i = 0; i< kout; i++)
227 fprintf(stderr, "%02x", (kbuf[i])&0xff);
228 fprintf(stderr, "\n");
230 shared_secret = BN_new();
232 BN_bin2bn(kbuf, kout, shared_secret);
233 memset(kbuf, 0, klen);
236 /* calc and verify H */
238 client_version_string,
239 server_version_string,
240 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
241 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
242 server_host_key_blob, sbloblen,
247 xfree(server_host_key_blob);
250 fprintf(stderr, "hash == ");
251 for (i = 0; i< 20; i++)
252 fprintf(stderr, "%02x", (hash[i])&0xff);
253 fprintf(stderr, "\n");
255 if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
256 fatal("key_verify failed for server_host_key");
257 key_free(server_host_key);
259 kex_derive_keys(kex, hash, shared_secret);
262 /* save session id */
263 session_id2_len = 20;
264 session_id2 = xmalloc(session_id2_len);
265 memcpy(session_id2, hash, session_id2_len);
268 /* diffie-hellman-group-exchange-sha1 */
271 * Estimates the group order for a Diffie-Hellman group that has an
272 * attack complexity approximately the same as O(2**bits). Estimate
273 * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
277 dh_estimate(int bits)
281 return (512); /* O(2**63) */
283 return (1024); /* O(2**86) */
285 return (2048); /* O(2**116) */
286 return (4096); /* O(2**156) */
290 ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
291 Buffer *client_kexinit, Buffer *server_kexinit)
297 unsigned int klen, kout;
298 char *signature = NULL;
299 unsigned int slen, nbits;
300 char *server_host_key_blob = NULL;
301 Key *server_host_key;
302 unsigned int sbloblen;
304 BIGNUM *dh_server_pub = 0;
305 BIGNUM *shared_secret = 0;
306 BIGNUM *p = 0, *g = 0;
310 nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8);
312 debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
313 packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
314 packet_put_int(nbits);
319 fprintf(stderr, "\nnbits = %d", nbits);
322 debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP.");
324 packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP);
326 debug("Got SSH2_MSG_KEX_DH_GEX_GROUP.");
328 if ((p = BN_new()) == NULL)
330 packet_get_bignum2(p, &dlen);
331 if ((g = BN_new()) == NULL)
333 packet_get_bignum2(g, &dlen);
334 if ((dh = dh_new_group(g, p)) == NULL)
335 fatal("dh_new_group");
338 fprintf(stderr, "\np= ");
339 BN_print_fp(stderr, dh->p);
340 fprintf(stderr, "\ng= ");
341 BN_print_fp(stderr, dh->g);
342 fprintf(stderr, "\npub= ");
343 BN_print_fp(stderr, dh->pub_key);
344 fprintf(stderr, "\n");
345 DHparams_print_fp(stderr, dh);
348 debug("Sending SSH2_MSG_KEX_DH_GEX_INIT.");
349 /* generate and send 'e', client DH public key */
350 packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
351 packet_put_bignum2(dh->pub_key);
355 debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY.");
357 packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY);
359 debug("Got SSH2_MSG_KEXDH_REPLY.");
362 server_host_key_blob = packet_get_string(&sbloblen);
363 server_host_key = key_from_blob(server_host_key_blob, sbloblen);
364 if (server_host_key == NULL)
365 fatal("cannot decode server_host_key_blob");
367 check_host_key(host, hostaddr, server_host_key,
368 options.user_hostfile2, options.system_hostfile2);
370 /* DH paramter f, server public DH key */
371 dh_server_pub = BN_new();
372 if (dh_server_pub == NULL)
373 fatal("dh_server_pub == NULL");
374 packet_get_bignum2(dh_server_pub, &dlen);
377 fprintf(stderr, "\ndh_server_pub= ");
378 BN_print_fp(stderr, dh_server_pub);
379 fprintf(stderr, "\n");
380 debug("bits %d", BN_num_bits(dh_server_pub));
384 signature = packet_get_string(&slen);
387 if (!dh_pub_is_valid(dh, dh_server_pub))
388 packet_disconnect("bad server public DH value");
391 kbuf = xmalloc(klen);
392 kout = DH_compute_key(kbuf, dh_server_pub, dh);
394 debug("shared secret: len %d/%d", klen, kout);
395 fprintf(stderr, "shared secret == ");
396 for (i = 0; i< kout; i++)
397 fprintf(stderr, "%02x", (kbuf[i])&0xff);
398 fprintf(stderr, "\n");
400 shared_secret = BN_new();
402 BN_bin2bn(kbuf, kout, shared_secret);
403 memset(kbuf, 0, klen);
406 /* calc and verify H */
408 client_version_string,
409 server_version_string,
410 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
411 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
412 server_host_key_blob, sbloblen,
418 xfree(server_host_key_blob);
421 fprintf(stderr, "hash == ");
422 for (i = 0; i< 20; i++)
423 fprintf(stderr, "%02x", (hash[i])&0xff);
424 fprintf(stderr, "\n");
426 if (key_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
427 fatal("key_verify failed for server_host_key");
428 key_free(server_host_key);
430 kex_derive_keys(kex, hash, shared_secret);
433 /* save session id */
434 session_id2_len = 20;
435 session_id2 = xmalloc(session_id2_len);
436 memcpy(session_id2, hash, session_id2_len);
443 typedef struct Authctxt Authctxt;
444 typedef struct Authmethod Authmethod;
446 typedef int sign_cb_fn(
447 Authctxt *authctxt, Key *key,
448 unsigned char **sigp, int *lenp, unsigned char *data, int datalen);
451 const char *server_user;
454 AuthenticationConnection *agent;
459 char *name; /* string to compare against server's list */
460 int (*userauth)(Authctxt *authctxt);
461 int *enabled; /* flag in option struct that enables method */
462 int *batch_flag; /* flag in option struct that disables method */
465 void input_userauth_success(int type, int plen, void *ctxt);
466 void input_userauth_failure(int type, int plen, void *ctxt);
467 void input_userauth_error(int type, int plen, void *ctxt);
468 void input_userauth_info_req(int type, int plen, void *ctxt);
470 int userauth_none(Authctxt *authctxt);
471 int userauth_pubkey(Authctxt *authctxt);
472 int userauth_passwd(Authctxt *authctxt);
473 int userauth_kbdint(Authctxt *authctxt);
475 void authmethod_clear();
476 Authmethod *authmethod_get(char *authlist);
477 Authmethod *authmethod_lookup(const char *name);
479 Authmethod authmethods[] = {
482 &options.pubkey_authentication,
486 &options.password_authentication,
487 &options.batch_mode},
488 {"keyboard-interactive",
490 &options.kbd_interactive_authentication,
491 &options.batch_mode},
496 {NULL, NULL, NULL, NULL}
500 ssh_userauth2(const char *server_user, char *host)
506 debug("send SSH2_MSG_SERVICE_REQUEST");
507 packet_start(SSH2_MSG_SERVICE_REQUEST);
508 packet_put_cstring("ssh-userauth");
511 type = packet_read(&plen);
512 if (type != SSH2_MSG_SERVICE_ACCEPT) {
513 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
515 if (packet_remaining() > 0) {
516 char *reply = packet_get_string(&plen);
517 debug("service_accept: %s", reply);
521 debug("buggy server: service_accept w/o service");
524 debug("got SSH2_MSG_SERVICE_ACCEPT");
526 /* setup authentication context */
527 authctxt.agent = ssh_get_authentication_connection();
528 authctxt.server_user = server_user;
529 authctxt.host = host;
530 authctxt.service = "ssh-connection"; /* service name */
531 authctxt.success = 0;
532 authctxt.method = authmethod_lookup("none");
533 if (authctxt.method == NULL)
534 fatal("ssh_userauth2: internal error: cannot send userauth none request");
537 /* initial userauth request */
538 userauth_none(&authctxt);
540 dispatch_init(&input_userauth_error);
541 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
542 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
543 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
545 if (authctxt.agent != NULL)
546 ssh_close_authentication_connection(authctxt.agent);
548 debug("ssh-userauth2 successfull: method %s", authctxt.method->name);
551 input_userauth_error(int type, int plen, void *ctxt)
553 fatal("input_userauth_error: bad message during authentication");
556 input_userauth_success(int type, int plen, void *ctxt)
558 Authctxt *authctxt = ctxt;
559 if (authctxt == NULL)
560 fatal("input_userauth_success: no authentication context");
561 authctxt->success = 1; /* break out */
564 input_userauth_failure(int type, int plen, void *ctxt)
566 Authmethod *method = NULL;
567 Authctxt *authctxt = ctxt;
568 char *authlist = NULL;
571 if (authctxt == NULL)
572 fatal("input_userauth_failure: no authentication context");
574 authlist = packet_get_string(NULL);
575 partial = packet_get_char();
579 debug("partial success");
580 debug("authentications that can continue: %s", authlist);
583 method = authmethod_get(authlist);
585 fatal("Unable to find an authentication method");
586 authctxt->method = method;
587 if (method->userauth(authctxt) != 0) {
588 debug2("we sent a %s packet, wait for reply", method->name);
591 debug2("we did not send a packet, disable method");
592 method->enabled = NULL;
599 userauth_none(Authctxt *authctxt)
601 /* initial userauth request */
602 packet_start(SSH2_MSG_USERAUTH_REQUEST);
603 packet_put_cstring(authctxt->server_user);
604 packet_put_cstring(authctxt->service);
605 packet_put_cstring(authctxt->method->name);
612 userauth_passwd(Authctxt *authctxt)
614 static int attempt = 0;
618 if (attempt++ >= options.number_of_password_prompts)
622 error("Permission denied, please try again.");
624 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
625 authctxt->server_user, authctxt->host);
626 password = read_passphrase(prompt, 0);
627 packet_start(SSH2_MSG_USERAUTH_REQUEST);
628 packet_put_cstring(authctxt->server_user);
629 packet_put_cstring(authctxt->service);
630 packet_put_cstring(authctxt->method->name);
632 packet_put_cstring(password);
633 memset(password, 0, strlen(password));
641 sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
644 unsigned char *blob, *signature;
650 debug3("sign_and_send_pubkey");
651 if (key_to_blob(k, &blob, &bloblen) == 0) {
652 /* we cannot handle this key */
653 debug3("sign_and_send_pubkey: cannot handle key");
656 /* data to be signed */
658 if (datafellows & SSH_OLD_SESSIONID) {
659 buffer_append(&b, session_id2, session_id2_len);
660 skip = session_id2_len;
662 buffer_put_string(&b, session_id2, session_id2_len);
663 skip = buffer_len(&b);
665 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
666 buffer_put_cstring(&b, authctxt->server_user);
667 buffer_put_cstring(&b,
668 datafellows & SSH_BUG_PKSERVICE ?
671 if (datafellows & SSH_BUG_PKAUTH) {
672 buffer_put_char(&b, have_sig);
674 buffer_put_cstring(&b, authctxt->method->name);
675 buffer_put_char(&b, have_sig);
676 buffer_put_cstring(&b, key_ssh_name(k));
678 buffer_put_string(&b, blob, bloblen);
680 /* generate signature */
681 ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
690 if (datafellows & SSH_BUG_PKSERVICE) {
692 buffer_append(&b, session_id2, session_id2_len);
693 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
694 buffer_put_cstring(&b, authctxt->server_user);
695 buffer_put_cstring(&b, authctxt->service);
696 buffer_put_cstring(&b, authctxt->method->name);
697 buffer_put_char(&b, have_sig);
698 if (!(datafellows & SSH_BUG_PKAUTH))
699 buffer_put_cstring(&b, key_ssh_name(k));
700 buffer_put_string(&b, blob, bloblen);
703 /* append signature */
704 buffer_put_string(&b, signature, slen);
707 /* skip session id and packet type */
708 if (buffer_len(&b) < skip + 1)
709 fatal("userauth_pubkey: internal error");
710 buffer_consume(&b, skip + 1);
712 /* put remaining data from buffer into packet */
713 packet_start(SSH2_MSG_USERAUTH_REQUEST);
714 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
725 int key_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp,
726 unsigned char *data, int datalen)
728 return key_sign(key, sigp, lenp, data, datalen);
732 userauth_pubkey_identity(Authctxt *authctxt, char *filename)
735 int i, ret, try_next;
738 if (stat(filename, &st) != 0) {
739 debug("key does not exist: %s", filename);
742 debug("try pubkey: %s", filename);
744 k = key_new(KEY_UNSPEC);
745 if (!load_private_key(filename, "", k, NULL)) {
749 snprintf(prompt, sizeof prompt,
750 "Enter passphrase for key '%.100s': ", filename);
751 for (i = 0; i < options.number_of_password_prompts; i++) {
752 passphrase = read_passphrase(prompt, 0);
753 if (strcmp(passphrase, "") != 0) {
754 success = load_private_key(filename, passphrase, k, NULL);
757 debug2("no passphrase given, try next key");
760 memset(passphrase, 0, strlen(passphrase));
762 if (success || try_next)
764 debug2("bad passphrase given, try again...");
771 ret = sign_and_send_pubkey(authctxt, k, key_sign_cb);
777 int agent_sign_cb(Authctxt *authctxt, Key *key, unsigned char **sigp, int *lenp,
778 unsigned char *data, int datalen)
780 return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
784 userauth_pubkey_agent(Authctxt *authctxt)
786 static int called = 0;
792 if (ssh_get_num_identities(authctxt->agent, 2) == 0)
793 debug2("userauth_pubkey_agent: no keys at all");
796 k = ssh_get_next_identity(authctxt->agent, &comment, 2);
798 debug2("userauth_pubkey_agent: no more keys");
800 debug("userauth_pubkey_agent: trying agent key %s", comment);
802 ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb);
806 debug2("userauth_pubkey_agent: no message sent");
811 userauth_pubkey(Authctxt *authctxt)
816 if (authctxt->agent != NULL) {
818 sent = userauth_pubkey_agent(authctxt);
819 } while(!sent && authctxt->agent->howmany > 0);
821 while (!sent && idx < options.num_identity_files) {
822 if (options.identity_files_type[idx] != KEY_RSA1)
823 sent = userauth_pubkey_identity(authctxt,
824 options.identity_files[idx]);
831 * Send userauth request message specifying keyboard-interactive method.
834 userauth_kbdint(Authctxt *authctxt)
836 static int attempt = 0;
838 if (attempt++ >= options.number_of_password_prompts)
841 debug2("userauth_kbdint");
842 packet_start(SSH2_MSG_USERAUTH_REQUEST);
843 packet_put_cstring(authctxt->server_user);
844 packet_put_cstring(authctxt->service);
845 packet_put_cstring(authctxt->method->name);
846 packet_put_cstring(""); /* lang */
847 packet_put_cstring(options.kbd_interactive_devices ?
848 options.kbd_interactive_devices : "");
852 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
857 * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send
858 * SSH2_MSG_USERAUTH_INFO_RESPONSE
861 input_userauth_info_req(int type, int plen, void *ctxt)
863 Authctxt *authctxt = ctxt;
868 char *response = NULL;
869 unsigned int num_prompts, i;
872 debug2("input_userauth_info_req");
874 if (authctxt == NULL)
875 fatal("input_userauth_info_req: no authentication context");
877 name = packet_get_string(NULL);
878 inst = packet_get_string(NULL);
879 lang = packet_get_string(NULL);
881 if (strlen(name) > 0)
885 if (strlen(inst) > 0)
888 xfree(lang); /* unused */
890 num_prompts = packet_get_int();
892 * Begin to build info response packet based on prompts requested.
893 * We commit to providing the correct number of responses, so if
894 * further on we run into a problem that prevents this, we have to
895 * be sure and clean this up and send a correct error response.
897 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
898 packet_put_int(num_prompts);
900 for (i = 0; i < num_prompts; i++) {
901 prompt = packet_get_string(NULL);
902 echo = packet_get_char();
904 response = cli_prompt(prompt, echo);
906 packet_put_cstring(response);
907 memset(response, 0, strlen(response));
911 packet_done(); /* done with parsing incoming message. */
917 /* find auth method */
921 static char *def_authlist = "publickey,password";
922 static char *authlist_current = NULL; /* clean copy used for comparison */
923 static char *authname_current = NULL; /* last used auth method */
924 static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */
925 static char *authlist_state = NULL; /* state variable for strtok_r() */
928 * Before starting to use a new authentication method list sent by the
929 * server, reset internal variables. This should also be called when
930 * finished processing server list to free resources.
935 if (authlist_current != NULL) {
936 xfree(authlist_current);
937 authlist_current = NULL;
939 if (authlist_working != NULL) {
940 xfree(authlist_working);
941 authlist_working = NULL;
943 if (authname_current != NULL) {
944 xfree(authname_current);
945 authlist_state = NULL;
947 if (authlist_state != NULL)
948 authlist_state = NULL;
953 * given auth method name, if configurable options permit this method fill
954 * in auth_ident field and return true, otherwise return false.
957 authmethod_is_enabled(Authmethod *method)
961 /* return false if options indicate this method is disabled */
962 if (method->enabled == NULL || *method->enabled == 0)
964 /* return false if batch mode is enabled but method needs interactive mode */
965 if (method->batch_flag != NULL && *method->batch_flag != 0)
971 authmethod_lookup(const char *name)
973 Authmethod *method = NULL;
975 for (method = authmethods; method->name != NULL; method++)
976 if (strcmp(name, method->name) == 0)
978 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
983 * Given the authentication method list sent by the server, return the
984 * next method we should try. If the server initially sends a nil list,
985 * use a built-in default list. If the server sends a nil list after
986 * previously sending a valid list, continue using the list originally
991 authmethod_get(char *authlist)
993 char *name = NULL, *authname_old;
994 Authmethod *method = NULL;
996 /* Use a suitable default if we're passed a nil list. */
997 if (authlist == NULL || strlen(authlist) == 0)
998 authlist = def_authlist;
1000 if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) {
1001 /* start over if passed a different list */
1002 debug3("start over, passed a different list");
1004 authlist_current = xstrdup(authlist);
1005 authlist_working = xstrdup(authlist);
1006 name = strtok_r(authlist_working, DELIM, &authlist_state);
1009 * try to use previously used authentication method
1010 * or continue to use previously passed list
1012 name = (authname_current != NULL) ?
1013 authname_current : strtok_r(NULL, DELIM, &authlist_state);
1016 while (name != NULL) {
1017 debug3("authmethod_lookup %s", name);
1018 method = authmethod_lookup(name);
1019 if (method != NULL && authmethod_is_enabled(method)) {
1020 debug3("authmethod_is_enabled %s", name);
1023 name = strtok_r(NULL, DELIM, &authlist_state);
1027 authname_old = authname_current;
1028 if (method != NULL) {
1029 debug("next auth method to try is %s", name);
1030 authname_current = xstrdup(name);
1032 debug("no more auth methods to try");
1033 authname_current = NULL;
1036 if (authname_old != NULL)
1037 xfree(authname_old);