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 1.35 2001/01/04 22:21:26 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 u_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)
155 char *signature = NULL;
157 char *server_host_key_blob = NULL;
158 Key *server_host_key;
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();
170 packet_start(SSH2_MSG_KEXDH_INIT);
171 packet_put_bignum2(dh->pub_key);
176 fprintf(stderr, "\np= ");
177 BN_print_fp(stderr, dh->p);
178 fprintf(stderr, "\ng= ");
179 BN_print_fp(stderr, dh->g);
180 fprintf(stderr, "\npub= ");
181 BN_print_fp(stderr, dh->pub_key);
182 fprintf(stderr, "\n");
183 DHparams_print_fp(stderr, dh);
186 debug("Wait SSH2_MSG_KEXDH_REPLY.");
188 packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
190 debug("Got SSH2_MSG_KEXDH_REPLY.");
193 server_host_key_blob = packet_get_string(&sbloblen);
194 server_host_key = key_from_blob(server_host_key_blob, sbloblen);
195 if (server_host_key == NULL)
196 fatal("cannot decode server_host_key_blob");
198 check_host_key(host, hostaddr, server_host_key,
199 options.user_hostfile2, options.system_hostfile2);
201 /* DH paramter f, server public DH key */
202 dh_server_pub = BN_new();
203 if (dh_server_pub == NULL)
204 fatal("dh_server_pub == NULL");
205 packet_get_bignum2(dh_server_pub, &dlen);
208 fprintf(stderr, "\ndh_server_pub= ");
209 BN_print_fp(stderr, dh_server_pub);
210 fprintf(stderr, "\n");
211 debug("bits %d", BN_num_bits(dh_server_pub));
215 signature = packet_get_string(&slen);
218 if (!dh_pub_is_valid(dh, dh_server_pub))
219 packet_disconnect("bad server public DH value");
222 kbuf = xmalloc(klen);
223 kout = DH_compute_key(kbuf, dh_server_pub, dh);
225 debug("shared secret: len %d/%d", klen, kout);
226 fprintf(stderr, "shared secret == ");
227 for (i = 0; i< kout; i++)
228 fprintf(stderr, "%02x", (kbuf[i])&0xff);
229 fprintf(stderr, "\n");
231 shared_secret = BN_new();
233 BN_bin2bn(kbuf, kout, shared_secret);
234 memset(kbuf, 0, klen);
237 /* calc and verify H */
239 client_version_string,
240 server_version_string,
241 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
242 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
243 server_host_key_blob, sbloblen,
248 xfree(server_host_key_blob);
251 fprintf(stderr, "hash == ");
252 for (i = 0; i< 20; i++)
253 fprintf(stderr, "%02x", (hash[i])&0xff);
254 fprintf(stderr, "\n");
256 if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1)
257 fatal("key_verify failed for server_host_key");
258 key_free(server_host_key);
260 kex_derive_keys(kex, hash, shared_secret);
263 /* save session id */
264 session_id2_len = 20;
265 session_id2 = xmalloc(session_id2_len);
266 memcpy(session_id2, hash, session_id2_len);
269 /* diffie-hellman-group-exchange-sha1 */
272 * Estimates the group order for a Diffie-Hellman group that has an
273 * attack complexity approximately the same as O(2**bits). Estimate
274 * with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
278 dh_estimate(int bits)
282 return (512); /* O(2**63) */
284 return (1024); /* O(2**86) */
286 return (2048); /* O(2**116) */
287 return (4096); /* O(2**156) */
291 ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr,
292 Buffer *client_kexinit, Buffer *server_kexinit)
299 char *signature = NULL;
301 char *server_host_key_blob = NULL;
302 Key *server_host_key;
305 BIGNUM *dh_server_pub = 0;
306 BIGNUM *shared_secret = 0;
307 BIGNUM *p = 0, *g = 0;
311 nbits = dh_estimate(kex->enc[MODE_OUT].cipher->key_len * 8);
313 debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST.");
314 packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
315 packet_put_int(nbits);
320 fprintf(stderr, "\nnbits = %d", nbits);
323 debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP.");
325 packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP);
327 debug("Got SSH2_MSG_KEX_DH_GEX_GROUP.");
329 if ((p = BN_new()) == NULL)
331 packet_get_bignum2(p, &dlen);
332 if ((g = BN_new()) == NULL)
334 packet_get_bignum2(g, &dlen);
335 if ((dh = dh_new_group(g, p)) == NULL)
336 fatal("dh_new_group");
341 fprintf(stderr, "\np= ");
342 BN_print_fp(stderr, dh->p);
343 fprintf(stderr, "\ng= ");
344 BN_print_fp(stderr, dh->g);
345 fprintf(stderr, "\npub= ");
346 BN_print_fp(stderr, dh->pub_key);
347 fprintf(stderr, "\n");
348 DHparams_print_fp(stderr, dh);
351 debug("Sending SSH2_MSG_KEX_DH_GEX_INIT.");
352 /* generate and send 'e', client DH public key */
353 packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
354 packet_put_bignum2(dh->pub_key);
358 debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY.");
360 packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY);
362 debug("Got SSH2_MSG_KEXDH_REPLY.");
365 server_host_key_blob = packet_get_string(&sbloblen);
366 server_host_key = key_from_blob(server_host_key_blob, sbloblen);
367 if (server_host_key == NULL)
368 fatal("cannot decode server_host_key_blob");
370 check_host_key(host, hostaddr, server_host_key,
371 options.user_hostfile2, options.system_hostfile2);
373 /* DH paramter f, server public DH key */
374 dh_server_pub = BN_new();
375 if (dh_server_pub == NULL)
376 fatal("dh_server_pub == NULL");
377 packet_get_bignum2(dh_server_pub, &dlen);
380 fprintf(stderr, "\ndh_server_pub= ");
381 BN_print_fp(stderr, dh_server_pub);
382 fprintf(stderr, "\n");
383 debug("bits %d", BN_num_bits(dh_server_pub));
387 signature = packet_get_string(&slen);
390 if (!dh_pub_is_valid(dh, dh_server_pub))
391 packet_disconnect("bad server public DH value");
394 kbuf = xmalloc(klen);
395 kout = DH_compute_key(kbuf, dh_server_pub, dh);
397 debug("shared secret: len %d/%d", klen, kout);
398 fprintf(stderr, "shared secret == ");
399 for (i = 0; i< kout; i++)
400 fprintf(stderr, "%02x", (kbuf[i])&0xff);
401 fprintf(stderr, "\n");
403 shared_secret = BN_new();
405 BN_bin2bn(kbuf, kout, shared_secret);
406 memset(kbuf, 0, klen);
409 /* calc and verify H */
411 client_version_string,
412 server_version_string,
413 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
414 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
415 server_host_key_blob, sbloblen,
421 xfree(server_host_key_blob);
424 fprintf(stderr, "hash == ");
425 for (i = 0; i< 20; i++)
426 fprintf(stderr, "%02x", (hash[i])&0xff);
427 fprintf(stderr, "\n");
429 if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1)
430 fatal("key_verify failed for server_host_key");
431 key_free(server_host_key);
433 kex_derive_keys(kex, hash, shared_secret);
436 /* save session id */
437 session_id2_len = 20;
438 session_id2 = xmalloc(session_id2_len);
439 memcpy(session_id2, hash, session_id2_len);
446 typedef struct Authctxt Authctxt;
447 typedef struct Authmethod Authmethod;
449 typedef int sign_cb_fn(
450 Authctxt *authctxt, Key *key,
451 u_char **sigp, int *lenp, u_char *data, int datalen);
454 const char *server_user;
457 AuthenticationConnection *agent;
462 char *name; /* string to compare against server's list */
463 int (*userauth)(Authctxt *authctxt);
464 int *enabled; /* flag in option struct that enables method */
465 int *batch_flag; /* flag in option struct that disables method */
468 void input_userauth_success(int type, int plen, void *ctxt);
469 void input_userauth_failure(int type, int plen, void *ctxt);
470 void input_userauth_banner(int type, int plen, void *ctxt);
471 void input_userauth_error(int type, int plen, void *ctxt);
472 void input_userauth_info_req(int type, int plen, void *ctxt);
474 int userauth_none(Authctxt *authctxt);
475 int userauth_pubkey(Authctxt *authctxt);
476 int userauth_passwd(Authctxt *authctxt);
477 int userauth_kbdint(Authctxt *authctxt);
479 void authmethod_clear(void);
480 Authmethod *authmethod_get(char *authlist);
481 Authmethod *authmethod_lookup(const char *name);
483 Authmethod authmethods[] = {
486 &options.pubkey_authentication,
490 &options.password_authentication,
491 &options.batch_mode},
492 {"keyboard-interactive",
494 &options.kbd_interactive_authentication,
495 &options.batch_mode},
500 {NULL, NULL, NULL, NULL}
504 ssh_userauth2(const char *server_user, char *host)
510 debug("send SSH2_MSG_SERVICE_REQUEST");
511 packet_start(SSH2_MSG_SERVICE_REQUEST);
512 packet_put_cstring("ssh-userauth");
515 type = packet_read(&plen);
516 if (type != SSH2_MSG_SERVICE_ACCEPT) {
517 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
519 if (packet_remaining() > 0) {
520 char *reply = packet_get_string(&plen);
521 debug("service_accept: %s", reply);
525 debug("buggy server: service_accept w/o service");
528 debug("got SSH2_MSG_SERVICE_ACCEPT");
530 /* setup authentication context */
531 authctxt.agent = ssh_get_authentication_connection();
532 authctxt.server_user = server_user;
533 authctxt.host = host;
534 authctxt.service = "ssh-connection"; /* service name */
535 authctxt.success = 0;
536 authctxt.method = authmethod_lookup("none");
537 if (authctxt.method == NULL)
538 fatal("ssh_userauth2: internal error: cannot send userauth none request");
541 /* initial userauth request */
542 userauth_none(&authctxt);
544 dispatch_init(&input_userauth_error);
545 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
546 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
547 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
548 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
550 if (authctxt.agent != NULL)
551 ssh_close_authentication_connection(authctxt.agent);
553 debug("ssh-userauth2 successful: method %s", authctxt.method->name);
556 input_userauth_error(int type, int plen, void *ctxt)
558 fatal("input_userauth_error: bad message during authentication: "
562 input_userauth_banner(int type, int plen, void *ctxt)
565 debug3("input_userauth_banner");
566 msg = packet_get_string(NULL);
567 lang = packet_get_string(NULL);
568 fprintf(stderr, "%s", msg);
573 input_userauth_success(int type, int plen, void *ctxt)
575 Authctxt *authctxt = ctxt;
576 if (authctxt == NULL)
577 fatal("input_userauth_success: no authentication context");
578 authctxt->success = 1; /* break out */
581 input_userauth_failure(int type, int plen, void *ctxt)
583 Authmethod *method = NULL;
584 Authctxt *authctxt = ctxt;
585 char *authlist = NULL;
588 if (authctxt == NULL)
589 fatal("input_userauth_failure: no authentication context");
591 authlist = packet_get_string(NULL);
592 partial = packet_get_char();
596 debug("partial success");
597 debug("authentications that can continue: %s", authlist);
600 method = authmethod_get(authlist);
602 fatal("Unable to find an authentication method");
603 authctxt->method = method;
604 if (method->userauth(authctxt) != 0) {
605 debug2("we sent a %s packet, wait for reply", method->name);
608 debug2("we did not send a packet, disable method");
609 method->enabled = NULL;
616 userauth_none(Authctxt *authctxt)
618 /* initial userauth request */
619 packet_start(SSH2_MSG_USERAUTH_REQUEST);
620 packet_put_cstring(authctxt->server_user);
621 packet_put_cstring(authctxt->service);
622 packet_put_cstring(authctxt->method->name);
629 userauth_passwd(Authctxt *authctxt)
631 static int attempt = 0;
635 if (attempt++ >= options.number_of_password_prompts)
639 error("Permission denied, please try again.");
641 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
642 authctxt->server_user, authctxt->host);
643 password = read_passphrase(prompt, 0);
644 packet_start(SSH2_MSG_USERAUTH_REQUEST);
645 packet_put_cstring(authctxt->server_user);
646 packet_put_cstring(authctxt->service);
647 packet_put_cstring(authctxt->method->name);
649 packet_put_cstring(password);
650 memset(password, 0, strlen(password));
658 sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
661 u_char *blob, *signature;
667 debug3("sign_and_send_pubkey");
668 if (key_to_blob(k, &blob, &bloblen) == 0) {
669 /* we cannot handle this key */
670 debug3("sign_and_send_pubkey: cannot handle key");
673 /* data to be signed */
675 if (datafellows & SSH_OLD_SESSIONID) {
676 buffer_append(&b, session_id2, session_id2_len);
677 skip = session_id2_len;
679 buffer_put_string(&b, session_id2, session_id2_len);
680 skip = buffer_len(&b);
682 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
683 buffer_put_cstring(&b, authctxt->server_user);
684 buffer_put_cstring(&b,
685 datafellows & SSH_BUG_PKSERVICE ?
688 if (datafellows & SSH_BUG_PKAUTH) {
689 buffer_put_char(&b, have_sig);
691 buffer_put_cstring(&b, authctxt->method->name);
692 buffer_put_char(&b, have_sig);
693 buffer_put_cstring(&b, key_ssh_name(k));
695 buffer_put_string(&b, blob, bloblen);
697 /* generate signature */
698 ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
707 if (datafellows & SSH_BUG_PKSERVICE) {
709 buffer_append(&b, session_id2, session_id2_len);
710 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
711 buffer_put_cstring(&b, authctxt->server_user);
712 buffer_put_cstring(&b, authctxt->service);
713 buffer_put_cstring(&b, authctxt->method->name);
714 buffer_put_char(&b, have_sig);
715 if (!(datafellows & SSH_BUG_PKAUTH))
716 buffer_put_cstring(&b, key_ssh_name(k));
717 buffer_put_string(&b, blob, bloblen);
720 /* append signature */
721 buffer_put_string(&b, signature, slen);
724 /* skip session id and packet type */
725 if (buffer_len(&b) < skip + 1)
726 fatal("userauth_pubkey: internal error");
727 buffer_consume(&b, skip + 1);
729 /* put remaining data from buffer into packet */
730 packet_start(SSH2_MSG_USERAUTH_REQUEST);
731 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
742 int key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp,
743 u_char *data, int datalen)
745 return key_sign(key, sigp, lenp, data, datalen);
749 userauth_pubkey_identity(Authctxt *authctxt, char *filename)
752 int i, ret, try_next;
755 if (stat(filename, &st) != 0) {
756 debug("key does not exist: %s", filename);
759 debug("try pubkey: %s", filename);
761 k = key_new(KEY_UNSPEC);
762 if (!load_private_key(filename, "", k, NULL)) {
766 snprintf(prompt, sizeof prompt,
767 "Enter passphrase for key '%.100s': ", filename);
768 for (i = 0; i < options.number_of_password_prompts; i++) {
769 passphrase = read_passphrase(prompt, 0);
770 if (strcmp(passphrase, "") != 0) {
771 success = load_private_key(filename, passphrase, k, NULL);
774 debug2("no passphrase given, try next key");
777 memset(passphrase, 0, strlen(passphrase));
779 if (success || try_next)
781 debug2("bad passphrase given, try again...");
788 ret = sign_and_send_pubkey(authctxt, k, key_sign_cb);
794 int agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp,
795 u_char *data, int datalen)
797 return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
801 userauth_pubkey_agent(Authctxt *authctxt)
803 static int called = 0;
809 if (ssh_get_num_identities(authctxt->agent, 2) == 0)
810 debug2("userauth_pubkey_agent: no keys at all");
813 k = ssh_get_next_identity(authctxt->agent, &comment, 2);
815 debug2("userauth_pubkey_agent: no more keys");
817 debug("userauth_pubkey_agent: trying agent key %s", comment);
819 ret = sign_and_send_pubkey(authctxt, k, agent_sign_cb);
823 debug2("userauth_pubkey_agent: no message sent");
828 userauth_pubkey(Authctxt *authctxt)
833 if (authctxt->agent != NULL) {
835 sent = userauth_pubkey_agent(authctxt);
836 } while(!sent && authctxt->agent->howmany > 0);
838 while (!sent && idx < options.num_identity_files) {
839 if (options.identity_files_type[idx] != KEY_RSA1)
840 sent = userauth_pubkey_identity(authctxt,
841 options.identity_files[idx]);
848 * Send userauth request message specifying keyboard-interactive method.
851 userauth_kbdint(Authctxt *authctxt)
853 static int attempt = 0;
855 if (attempt++ >= options.number_of_password_prompts)
858 debug2("userauth_kbdint");
859 packet_start(SSH2_MSG_USERAUTH_REQUEST);
860 packet_put_cstring(authctxt->server_user);
861 packet_put_cstring(authctxt->service);
862 packet_put_cstring(authctxt->method->name);
863 packet_put_cstring(""); /* lang */
864 packet_put_cstring(options.kbd_interactive_devices ?
865 options.kbd_interactive_devices : "");
869 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
874 * parse SSH2_MSG_USERAUTH_INFO_REQUEST, prompt user and send
875 * SSH2_MSG_USERAUTH_INFO_RESPONSE
878 input_userauth_info_req(int type, int plen, void *ctxt)
880 Authctxt *authctxt = ctxt;
885 char *response = NULL;
886 u_int num_prompts, i;
889 debug2("input_userauth_info_req");
891 if (authctxt == NULL)
892 fatal("input_userauth_info_req: no authentication context");
894 name = packet_get_string(NULL);
895 inst = packet_get_string(NULL);
896 lang = packet_get_string(NULL);
898 if (strlen(name) > 0)
902 if (strlen(inst) > 0)
905 xfree(lang); /* unused */
907 num_prompts = packet_get_int();
909 * Begin to build info response packet based on prompts requested.
910 * We commit to providing the correct number of responses, so if
911 * further on we run into a problem that prevents this, we have to
912 * be sure and clean this up and send a correct error response.
914 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
915 packet_put_int(num_prompts);
917 for (i = 0; i < num_prompts; i++) {
918 prompt = packet_get_string(NULL);
919 echo = packet_get_char();
921 response = cli_prompt(prompt, echo);
923 packet_put_cstring(response);
924 memset(response, 0, strlen(response));
928 packet_done(); /* done with parsing incoming message. */
934 /* find auth method */
938 static char *def_authlist = "publickey,password";
939 static char *authlist_current = NULL; /* clean copy used for comparison */
940 static char *authname_current = NULL; /* last used auth method */
941 static char *authlist_working = NULL; /* copy that gets modified by strtok_r() */
942 static char *authlist_state = NULL; /* state variable for strtok_r() */
945 * Before starting to use a new authentication method list sent by the
946 * server, reset internal variables. This should also be called when
947 * finished processing server list to free resources.
950 authmethod_clear(void)
952 if (authlist_current != NULL) {
953 xfree(authlist_current);
954 authlist_current = NULL;
956 if (authlist_working != NULL) {
957 xfree(authlist_working);
958 authlist_working = NULL;
960 if (authname_current != NULL) {
961 xfree(authname_current);
962 authlist_state = NULL;
964 if (authlist_state != NULL)
965 authlist_state = NULL;
970 * given auth method name, if configurable options permit this method fill
971 * in auth_ident field and return true, otherwise return false.
974 authmethod_is_enabled(Authmethod *method)
978 /* return false if options indicate this method is disabled */
979 if (method->enabled == NULL || *method->enabled == 0)
981 /* return false if batch mode is enabled but method needs interactive mode */
982 if (method->batch_flag != NULL && *method->batch_flag != 0)
988 authmethod_lookup(const char *name)
990 Authmethod *method = NULL;
992 for (method = authmethods; method->name != NULL; method++)
993 if (strcmp(name, method->name) == 0)
995 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1000 * Given the authentication method list sent by the server, return the
1001 * next method we should try. If the server initially sends a nil list,
1002 * use a built-in default list. If the server sends a nil list after
1003 * previously sending a valid list, continue using the list originally
1008 authmethod_get(char *authlist)
1010 char *name = NULL, *authname_old;
1011 Authmethod *method = NULL;
1013 /* Use a suitable default if we're passed a nil list. */
1014 if (authlist == NULL || strlen(authlist) == 0)
1015 authlist = def_authlist;
1017 if (authlist_current == NULL || strcmp(authlist, authlist_current) != 0) {
1018 /* start over if passed a different list */
1019 debug3("start over, passed a different list");
1021 authlist_current = xstrdup(authlist);
1022 authlist_working = xstrdup(authlist);
1023 name = strtok_r(authlist_working, DELIM, &authlist_state);
1026 * try to use previously used authentication method
1027 * or continue to use previously passed list
1029 name = (authname_current != NULL) ?
1030 authname_current : strtok_r(NULL, DELIM, &authlist_state);
1033 while (name != NULL) {
1034 debug3("authmethod_lookup %s", name);
1035 method = authmethod_lookup(name);
1036 if (method != NULL && authmethod_is_enabled(method)) {
1037 debug3("authmethod_is_enabled %s", name);
1040 name = strtok_r(NULL, DELIM, &authlist_state);
1044 authname_old = authname_current;
1045 if (method != NULL) {
1046 debug("next auth method to try is %s", name);
1047 authname_current = xstrdup(name);
1049 debug("no more auth methods to try");
1050 authname_current = NULL;
1053 if (authname_old != NULL)
1054 xfree(authname_old);