]> andersk Git - openssh.git/blobdiff - sshconnect2.c
- (djm) OpenBSD CVS Sync
[openssh.git] / sshconnect2.c
index 1f49067adf0bd77ba2fc576402d8aeb76c114d52..1f92f02965ea1ee5f5e6349cbfe665bb6f9ddf89 100644 (file)
@@ -9,11 +9,6 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *      This product includes software developed by Markus Friedl.
- * 4. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect2.c,v 1.17 2000/08/19 21:34:44 markus Exp $");
-
-#include <openssl/bn.h>
-#include <openssl/rsa.h>
-#include <openssl/dsa.h>
-#include <openssl/md5.h>
-#include <openssl/dh.h>
-#include <openssl/hmac.h>
+RCSID("$OpenBSD: sshconnect2.c,v 1.112 2003/03/05 22:33:43 markus Exp $");
 
 #include "ssh.h"
+#include "ssh2.h"
 #include "xmalloc.h"
-#include "rsa.h"
 #include "buffer.h"
 #include "packet.h"
-#include "cipher.h"
-#include "uidswap.h"
 #include "compat.h"
-#include "readconf.h"
 #include "bufaux.h"
-#include "ssh2.h"
+#include "cipher.h"
 #include "kex.h"
 #include "myproposal.h"
-#include "key.h"
-#include "dsa.h"
 #include "sshconnect.h"
 #include "authfile.h"
+#include "dh.h"
 #include "authfd.h"
+#include "log.h"
+#include "readconf.h"
+#include "readpass.h"
+#include "match.h"
+#include "dispatch.h"
+#include "canohost.h"
+#include "msg.h"
+#include "pathnames.h"
 
 /* import */
 extern char *client_version_string;
@@ -65,466 +57,1112 @@ extern Options options;
  * SSH2 key exchange
  */
 
-unsigned char *session_id2 = NULL;
+u_char *session_id2 = NULL;
 int session_id2_len = 0;
 
+char *xxx_host;
+struct sockaddr *xxx_hostaddr;
+
+Kex *xxx_kex = NULL;
+
+static int
+verify_host_key_callback(Key *hostkey)
+{
+       if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
+               fatal("Host key verification failed.");
+       return 0;
+}
+
 void
-ssh_kex_dh(Kex *kex, char *host, struct sockaddr *hostaddr,
-    Buffer *client_kexinit, Buffer *server_kexinit)
+ssh_kex2(char *host, struct sockaddr *hostaddr)
 {
-       int plen, dlen;
-       unsigned int klen, kout;
-       char *signature = NULL;
-       unsigned int slen;
-       char *server_host_key_blob = NULL;
-       Key *server_host_key;
-       unsigned int sbloblen;
-       DH *dh;
-       BIGNUM *dh_server_pub = 0;
-       BIGNUM *shared_secret = 0;
-       unsigned char *kbuf;
-       unsigned char *hash;
-
-       debug("Sending SSH2_MSG_KEXDH_INIT.");
-       /* generate and send 'e', client DH public key */
-       dh = dh_new_group1();
-       packet_start(SSH2_MSG_KEXDH_INIT);
-       packet_put_bignum2(dh->pub_key);
-       packet_send();
-       packet_write_wait();
+       Kex *kex;
+
+       xxx_host = host;
+       xxx_hostaddr = hostaddr;
+
+       if (options.ciphers == (char *)-1) {
+               log("No valid ciphers for protocol version 2 given, using defaults.");
+               options.ciphers = NULL;
+       }
+       if (options.ciphers != NULL) {
+               myproposal[PROPOSAL_ENC_ALGS_CTOS] =
+               myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
+       }
+       myproposal[PROPOSAL_ENC_ALGS_CTOS] =
+           compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
+       myproposal[PROPOSAL_ENC_ALGS_STOC] =
+           compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
+       if (options.compression) {
+               myproposal[PROPOSAL_COMP_ALGS_CTOS] =
+               myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none";
+       } else {
+               myproposal[PROPOSAL_COMP_ALGS_CTOS] =
+               myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib";
+       }
+       if (options.macs != NULL) {
+               myproposal[PROPOSAL_MAC_ALGS_CTOS] =
+               myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
+       }
+       if (options.hostkeyalgorithms != NULL)
+               myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
+                   options.hostkeyalgorithms;
+
+       /* start key exchange */
+       kex = kex_setup(myproposal);
+       kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
+       kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
+       kex->client_version_string=client_version_string;
+       kex->server_version_string=server_version_string;
+       kex->verify_host_key=&verify_host_key_callback;
+
+       xxx_kex = kex;
+
+       dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
+
+       session_id2 = kex->session_id;
+       session_id2_len = kex->session_id_len;
 
 #ifdef DEBUG_KEXDH
-       fprintf(stderr, "\np= ");
-       bignum_print(dh->p);
-       fprintf(stderr, "\ng= ");
-       bignum_print(dh->g);
-       fprintf(stderr, "\npub= ");
-       bignum_print(dh->pub_key);
-       fprintf(stderr, "\n");
-       DHparams_print_fp(stderr, dh);
+       /* send 1st encrypted/maced/compressed message */
+       packet_start(SSH2_MSG_IGNORE);
+       packet_put_cstring("markus");
+       packet_send();
+       packet_write_wait();
 #endif
+}
 
-       debug("Wait SSH2_MSG_KEXDH_REPLY.");
+/*
+ * Authenticate user
+ */
 
-       packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
+typedef struct Authctxt Authctxt;
+typedef struct Authmethod Authmethod;
 
-       debug("Got SSH2_MSG_KEXDH_REPLY.");
+typedef int sign_cb_fn(
+    Authctxt *authctxt, Key *key,
+    u_char **sigp, u_int *lenp, u_char *data, u_int datalen);
 
-       /* key, cert */
-       server_host_key_blob = packet_get_string(&sbloblen);
-       server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
-       if (server_host_key == NULL)
-               fatal("cannot decode server_host_key_blob");
+struct Authctxt {
+       const char *server_user;
+       const char *local_user;
+       const char *host;
+       const char *service;
+       Authmethod *method;
+       int success;
+       char *authlist;
+       /* pubkey */
+       Key *last_key;
+       sign_cb_fn *last_key_sign;
+       int last_key_hint;
+       AuthenticationConnection *agent;
+       /* hostbased */
+       Sensitive *sensitive;
+       /* kbd-interactive */
+       int info_req_seen;
+};
+struct Authmethod {
+       char    *name;          /* string to compare against server's list */
+       int     (*userauth)(Authctxt *authctxt);
+       int     *enabled;       /* flag in option struct that enables method */
+       int     *batch_flag;    /* flag in option struct that disables method */
+};
 
-       check_host_key(host, hostaddr, server_host_key,
-           options.user_hostfile2, options.system_hostfile2);
+void   input_userauth_success(int, u_int32_t, void *);
+void   input_userauth_failure(int, u_int32_t, void *);
+void   input_userauth_banner(int, u_int32_t, void *);
+void   input_userauth_error(int, u_int32_t, void *);
+void   input_userauth_info_req(int, u_int32_t, void *);
+void   input_userauth_pk_ok(int, u_int32_t, void *);
+void   input_userauth_passwd_changereq(int, u_int32_t, void *);
 
-       /* DH paramter f, server public DH key */
-       dh_server_pub = BN_new();
-       if (dh_server_pub == NULL)
-               fatal("dh_server_pub == NULL");
-       packet_get_bignum2(dh_server_pub, &dlen);
+int    userauth_none(Authctxt *);
+int    userauth_pubkey(Authctxt *);
+int    userauth_passwd(Authctxt *);
+int    userauth_kbdint(Authctxt *);
+int    userauth_hostbased(Authctxt *);
 
-#ifdef DEBUG_KEXDH
-       fprintf(stderr, "\ndh_server_pub= ");
-       bignum_print(dh_server_pub);
-       fprintf(stderr, "\n");
-       debug("bits %d", BN_num_bits(dh_server_pub));
-#endif
+void   userauth(Authctxt *, char *);
 
-       /* signed H */
-       signature = packet_get_string(&slen);
-       packet_done();
+static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *);
+static void clear_auth_state(Authctxt *);
 
-       if (!dh_pub_is_valid(dh, dh_server_pub))
-               packet_disconnect("bad server public DH value");
+static Authmethod *authmethod_get(char *authlist);
+static Authmethod *authmethod_lookup(const char *name);
+static char *authmethods_get(void);
 
-       klen = DH_size(dh);
-       kbuf = xmalloc(klen);
-       kout = DH_compute_key(kbuf, dh_server_pub, dh);
-#ifdef DEBUG_KEXDH
-       debug("shared secret: len %d/%d", klen, kout);
-       fprintf(stderr, "shared secret == ");
-       for (i = 0; i< kout; i++)
-               fprintf(stderr, "%02x", (kbuf[i])&0xff);
-       fprintf(stderr, "\n");
-#endif
-       shared_secret = BN_new();
-
-       BN_bin2bn(kbuf, kout, shared_secret);
-       memset(kbuf, 0, klen);
-       xfree(kbuf);
-
-       /* calc and verify H */
-       hash = kex_hash(
-           client_version_string,
-           server_version_string,
-           buffer_ptr(client_kexinit), buffer_len(client_kexinit),
-           buffer_ptr(server_kexinit), buffer_len(server_kexinit),
-           server_host_key_blob, sbloblen,
-           dh->pub_key,
-           dh_server_pub,
-           shared_secret
-       );
-       xfree(server_host_key_blob);
-       DH_free(dh);
-#ifdef DEBUG_KEXDH
-       fprintf(stderr, "hash == ");
-       for (i = 0; i< 20; i++)
-               fprintf(stderr, "%02x", (hash[i])&0xff);
-       fprintf(stderr, "\n");
-#endif
-       if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
-               fatal("dsa_verify failed for server_host_key");
-       key_free(server_host_key);
+Authmethod authmethods[] = {
+       {"hostbased",
+               userauth_hostbased,
+               &options.hostbased_authentication,
+               NULL},
+       {"publickey",
+               userauth_pubkey,
+               &options.pubkey_authentication,
+               NULL},
+       {"keyboard-interactive",
+               userauth_kbdint,
+               &options.kbd_interactive_authentication,
+               &options.batch_mode},
+       {"password",
+               userauth_passwd,
+               &options.password_authentication,
+               &options.batch_mode},
+       {"none",
+               userauth_none,
+               NULL,
+               NULL},
+       {NULL, NULL, NULL, NULL}
+};
+
+void
+ssh_userauth2(const char *local_user, const char *server_user, char *host,
+    Sensitive *sensitive)
+{
+       Authctxt authctxt;
+       int type;
+
+       if (options.challenge_response_authentication)
+               options.kbd_interactive_authentication = 1;
+
+       packet_start(SSH2_MSG_SERVICE_REQUEST);
+       packet_put_cstring("ssh-userauth");
+       packet_send();
+       debug("SSH2_MSG_SERVICE_REQUEST sent");
+       packet_write_wait();
+       type = packet_read();
+       if (type != SSH2_MSG_SERVICE_ACCEPT)
+               fatal("Server denied authentication request: %d", type);
+       if (packet_remaining() > 0) {
+               char *reply = packet_get_string(NULL);
+               debug2("service_accept: %s", reply);
+               xfree(reply);
+       } else {
+               debug2("buggy server: service_accept w/o service");
+       }
+       packet_check_eom();
+       debug("SSH2_MSG_SERVICE_ACCEPT received");
+
+       if (options.preferred_authentications == NULL)
+               options.preferred_authentications = authmethods_get();
+
+       /* setup authentication context */
+       memset(&authctxt, 0, sizeof(authctxt));
+       authctxt.agent = ssh_get_authentication_connection();
+       authctxt.server_user = server_user;
+       authctxt.local_user = local_user;
+       authctxt.host = host;
+       authctxt.service = "ssh-connection";            /* service name */
+       authctxt.success = 0;
+       authctxt.method = authmethod_lookup("none");
+       authctxt.authlist = NULL;
+       authctxt.sensitive = sensitive;
+       authctxt.info_req_seen = 0;
+       if (authctxt.method == NULL)
+               fatal("ssh_userauth2: internal error: cannot send userauth none request");
+
+       /* initial userauth request */
+       userauth_none(&authctxt);
 
-       kex_derive_keys(kex, hash, shared_secret);
-       packet_set_kex(kex);
+       dispatch_init(&input_userauth_error);
+       dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
+       dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
+       dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
+       dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);     /* loop until success */
 
-       /* save session id */
-       session_id2_len = 20;
-       session_id2 = xmalloc(session_id2_len);
-       memcpy(session_id2, hash, session_id2_len);
+       if (authctxt.agent != NULL)
+               ssh_close_authentication_connection(authctxt.agent);
+
+       debug("Authentication succeeded (%s).", authctxt.method->name);
+}
+void
+userauth(Authctxt *authctxt, char *authlist)
+{
+       if (authlist == NULL) {
+               authlist = authctxt->authlist;
+       } else {
+               if (authctxt->authlist)
+                       xfree(authctxt->authlist);
+               authctxt->authlist = authlist;
+       }
+       for (;;) {
+               Authmethod *method = authmethod_get(authlist);
+               if (method == NULL)
+                       fatal("Permission denied (%s).", authlist);
+               authctxt->method = method;
+               if (method->userauth(authctxt) != 0) {
+                       debug2("we sent a %s packet, wait for reply", method->name);
+                       break;
+               } else {
+                       debug2("we did not send a packet, disable method");
+                       method->enabled = NULL;
+               }
+       }
 }
 
 void
-ssh_kex2(char *host, struct sockaddr *hostaddr)
+input_userauth_error(int type, u_int32_t seq, void *ctxt)
 {
-       int i, plen;
-       Kex *kex;
-       Buffer *client_kexinit, *server_kexinit;
-       char *sprop[PROPOSAL_MAX];
+       fatal("input_userauth_error: bad message during authentication: "
+          "type %d", type);
+}
 
-       if (options.ciphers != NULL) {
-               myproposal[PROPOSAL_ENC_ALGS_CTOS] =
-               myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
-       } else if (options.cipher == SSH_CIPHER_3DES) {
-               myproposal[PROPOSAL_ENC_ALGS_CTOS] =
-               myproposal[PROPOSAL_ENC_ALGS_STOC] =
-                   (char *) cipher_name(SSH_CIPHER_3DES_CBC);
-       } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
-               myproposal[PROPOSAL_ENC_ALGS_CTOS] =
-               myproposal[PROPOSAL_ENC_ALGS_STOC] =
-                   (char *) cipher_name(SSH_CIPHER_BLOWFISH_CBC);
-       }
-       if (options.compression) {
-               myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
-               myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
+void
+input_userauth_banner(int type, u_int32_t seq, void *ctxt)
+{
+       char *msg, *lang;
+       debug3("input_userauth_banner");
+       msg = packet_get_string(NULL);
+       lang = packet_get_string(NULL);
+       fprintf(stderr, "%s", msg);
+       xfree(msg);
+       xfree(lang);
+}
+
+void
+input_userauth_success(int type, u_int32_t seq, void *ctxt)
+{
+       Authctxt *authctxt = ctxt;
+       if (authctxt == NULL)
+               fatal("input_userauth_success: no authentication context");
+       if (authctxt->authlist)
+               xfree(authctxt->authlist);
+       clear_auth_state(authctxt);
+       authctxt->success = 1;                  /* break out */
+}
+
+void
+input_userauth_failure(int type, u_int32_t seq, void *ctxt)
+{
+       Authctxt *authctxt = ctxt;
+       char *authlist = NULL;
+       int partial;
+
+       if (authctxt == NULL)
+               fatal("input_userauth_failure: no authentication context");
+
+       authlist = packet_get_string(NULL);
+       partial = packet_get_char();
+       packet_check_eom();
+
+       if (partial != 0)
+               log("Authenticated with partial success.");
+       debug("Authentications that can continue: %s", authlist);
+
+       clear_auth_state(authctxt);
+       userauth(authctxt, authlist);
+}
+void
+input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
+{
+       Authctxt *authctxt = ctxt;
+       Key *key = NULL;
+       Buffer b;
+       int pktype, sent = 0;
+       u_int alen, blen;
+       char *pkalg, *fp;
+       u_char *pkblob;
+
+       if (authctxt == NULL)
+               fatal("input_userauth_pk_ok: no authentication context");
+       if (datafellows & SSH_BUG_PKOK) {
+               /* this is similar to SSH_BUG_PKAUTH */
+               debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
+               pkblob = packet_get_string(&blen);
+               buffer_init(&b);
+               buffer_append(&b, pkblob, blen);
+               pkalg = buffer_get_string(&b, &alen);
+               buffer_free(&b);
        } else {
-               myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
-               myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
+               pkalg = packet_get_string(&alen);
+               pkblob = packet_get_string(&blen);
        }
+       packet_check_eom();
 
-       /* buffers with raw kexinit messages */
-       server_kexinit = xmalloc(sizeof(*server_kexinit));
-       buffer_init(server_kexinit);
-       client_kexinit = kex_init(myproposal);
+       debug("Server accepts key: pkalg %s blen %u lastkey %p hint %d",
+           pkalg, blen, authctxt->last_key, authctxt->last_key_hint);
 
-       /* algorithm negotiation */
-       kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
-       kex = kex_choose_conf(myproposal, sprop, 0);
-       for (i = 0; i < PROPOSAL_MAX; i++)
-               xfree(sprop[i]);
+       do {
+               if (authctxt->last_key == NULL ||
+                   authctxt->last_key_sign == NULL) {
+                       debug("no last key or no sign cb");
+                       break;
+               }
+               if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
+                       debug("unknown pkalg %s", pkalg);
+                       break;
+               }
+               if ((key = key_from_blob(pkblob, blen)) == NULL) {
+                       debug("no key from blob. pkalg %s", pkalg);
+                       break;
+               }
+               if (key->type != pktype) {
+                       error("input_userauth_pk_ok: type mismatch "
+                           "for decoded key (received %d, expected %d)",
+                           key->type, pktype);
+                       break;
+               }
+               fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+               debug2("input_userauth_pk_ok: fp %s", fp);
+               xfree(fp);
+               if (!key_equal(key, authctxt->last_key)) {
+                       debug("key != last_key");
+                       break;
+               }
+               sent = sign_and_send_pubkey(authctxt, key,
+                  authctxt->last_key_sign);
+       } while (0);
 
-       /* server authentication and session key agreement */
-       ssh_kex_dh(kex, host, hostaddr, client_kexinit, server_kexinit);
+       if (key != NULL)
+               key_free(key);
+       xfree(pkalg);
+       xfree(pkblob);
 
-       buffer_free(client_kexinit);
-       buffer_free(server_kexinit);
-       xfree(client_kexinit);
-       xfree(server_kexinit);
+       /* unregister */
+       clear_auth_state(authctxt);
+       dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL);
 
-       debug("Wait SSH2_MSG_NEWKEYS.");
-       packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
-       packet_done();
-       debug("GOT SSH2_MSG_NEWKEYS.");
+       /* try another method if we did not send a packet */
+       if (sent == 0)
+               userauth(authctxt, NULL);
 
-       debug("send SSH2_MSG_NEWKEYS.");
-       packet_start(SSH2_MSG_NEWKEYS);
-       packet_send();
-       packet_write_wait();
-       debug("done: send SSH2_MSG_NEWKEYS.");
+}
 
-#ifdef DEBUG_KEXDH
-       /* send 1st encrypted/maced/compressed message */
-       packet_start(SSH2_MSG_IGNORE);
-       packet_put_cstring("markus");
+int
+userauth_none(Authctxt *authctxt)
+{
+       /* initial userauth request */
+       packet_start(SSH2_MSG_USERAUTH_REQUEST);
+       packet_put_cstring(authctxt->server_user);
+       packet_put_cstring(authctxt->service);
+       packet_put_cstring(authctxt->method->name);
        packet_send();
-       packet_write_wait();
-#endif
-       debug("done: KEX2.");
+       return 1;
 }
 
-/*
- * Authenticate user
- */
 int
-ssh2_try_passwd(const char *server_user, const char *host, const char *service)
+userauth_passwd(Authctxt *authctxt)
 {
        static int attempt = 0;
-       char prompt[80];
+       char prompt[150];
        char *password;
 
        if (attempt++ >= options.number_of_password_prompts)
                return 0;
 
-       if(attempt != 1)
+       if (attempt != 1)
                error("Permission denied, please try again.");
 
-       snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
-           server_user, host);
+       snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
+           authctxt->server_user, authctxt->host);
        password = read_passphrase(prompt, 0);
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
-       packet_put_cstring(server_user);
-       packet_put_cstring(service);
-       packet_put_cstring("password");
+       packet_put_cstring(authctxt->server_user);
+       packet_put_cstring(authctxt->service);
+       packet_put_cstring(authctxt->method->name);
        packet_put_char(0);
        packet_put_cstring(password);
        memset(password, 0, strlen(password));
        xfree(password);
+       packet_add_padding(64);
        packet_send();
-       packet_write_wait();
+
+       dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
+           &input_userauth_passwd_changereq);
+
        return 1;
 }
+/*
+ * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
+ */
+void
+input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
+{
+       Authctxt *authctxt = ctxt;
+       char *info, *lang, *password = NULL, *retype = NULL;
+       char prompt[150];
 
-typedef int sign_fn(
-    Key *key,
-    unsigned char **sigp, int *lenp,
-    unsigned char *data, int datalen);
+       debug2("input_userauth_passwd_changereq");
 
-int
-ssh2_sign_and_send_pubkey(Key *k, sign_fn *do_sign,
-    const char *server_user, const char *host, const char *service)
+       if (authctxt == NULL)
+               fatal("input_userauth_passwd_changereq: "
+                   "no authentication context");
+
+       info = packet_get_string(NULL);
+       lang = packet_get_string(NULL);
+       if (strlen(info) > 0)
+               log("%s", info);
+       xfree(info);
+       xfree(lang);
+       packet_start(SSH2_MSG_USERAUTH_REQUEST);
+       packet_put_cstring(authctxt->server_user);
+       packet_put_cstring(authctxt->service);
+       packet_put_cstring(authctxt->method->name);
+       packet_put_char(1);                     /* additional info */
+       snprintf(prompt, sizeof(prompt),
+           "Enter %.30s@%.128s's old password: ",
+           authctxt->server_user, authctxt->host);
+       password = read_passphrase(prompt, 0);
+       packet_put_cstring(password);
+       memset(password, 0, strlen(password));
+       xfree(password);
+       password = NULL;
+       while (password == NULL) {
+               snprintf(prompt, sizeof(prompt),
+                   "Enter %.30s@%.128s's new password: ",
+                   authctxt->server_user, authctxt->host);
+               password = read_passphrase(prompt, RP_ALLOW_EOF);
+               if (password == NULL) {
+                       /* bail out */
+                       return;
+               }
+               snprintf(prompt, sizeof(prompt),
+                   "Retype %.30s@%.128s's new password: ",
+                   authctxt->server_user, authctxt->host);
+               retype = read_passphrase(prompt, 0);
+               if (strcmp(password, retype) != 0) {
+                       memset(password, 0, strlen(password));
+                       xfree(password);
+                       log("Mismatch; try again, EOF to quit.");
+                       password = NULL;
+               }
+               memset(retype, 0, strlen(retype));
+               xfree(retype);
+       }
+       packet_put_cstring(password);
+       memset(password, 0, strlen(password));
+       xfree(password);
+       packet_add_padding(64);
+       packet_send();
+
+       dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
+           &input_userauth_passwd_changereq);
+}
+
+static void
+clear_auth_state(Authctxt *authctxt)
+{
+       /* XXX clear authentication state */
+       dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL);
+
+       if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) {
+               debug3("clear_auth_state: key_free %p", authctxt->last_key);
+               key_free(authctxt->last_key);
+       }
+       authctxt->last_key = NULL;
+       authctxt->last_key_hint = -2;
+       authctxt->last_key_sign = NULL;
+}
+
+static int
+sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback)
 {
        Buffer b;
-       unsigned char *blob, *signature;
-       int bloblen, slen;
+       u_char *blob, *signature;
+       u_int bloblen, slen;
        int skip = 0;
        int ret = -1;
+       int have_sig = 1;
 
-       dsa_make_key_blob(k, &blob, &bloblen);
+       debug3("sign_and_send_pubkey");
 
+       if (key_to_blob(k, &blob, &bloblen) == 0) {
+               /* we cannot handle this key */
+               debug3("sign_and_send_pubkey: cannot handle key");
+               return 0;
+       }
        /* data to be signed */
        buffer_init(&b);
-       if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
+       if (datafellows & SSH_OLD_SESSIONID) {
+               buffer_append(&b, session_id2, session_id2_len);
+               skip = session_id2_len;
+       } else {
                buffer_put_string(&b, session_id2, session_id2_len);
                skip = buffer_len(&b);
-       } else {
-               buffer_append(&b, session_id2, session_id2_len);
-               skip = session_id2_len; 
        }
        buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
-       buffer_put_cstring(&b, server_user);
+       buffer_put_cstring(&b, authctxt->server_user);
        buffer_put_cstring(&b,
-           datafellows & SSH_BUG_PUBKEYAUTH ?
+           datafellows & SSH_BUG_PKSERVICE ?
            "ssh-userauth" :
-           service);
-       buffer_put_cstring(&b, "publickey");
-       buffer_put_char(&b, 1);
-       buffer_put_cstring(&b, KEX_DSS); 
+           authctxt->service);
+       if (datafellows & SSH_BUG_PKAUTH) {
+               buffer_put_char(&b, have_sig);
+       } else {
+               buffer_put_cstring(&b, authctxt->method->name);
+               buffer_put_char(&b, have_sig);
+               buffer_put_cstring(&b, key_ssh_name(k));
+       }
        buffer_put_string(&b, blob, bloblen);
 
        /* generate signature */
-       ret = do_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
+       ret = (*sign_callback)(authctxt, k, &signature, &slen,
+           buffer_ptr(&b), buffer_len(&b));
        if (ret == -1) {
                xfree(blob);
                buffer_free(&b);
                return 0;
        }
-#ifdef DEBUG_DSS
+#ifdef DEBUG_PK
        buffer_dump(&b);
 #endif
-       if (datafellows & SSH_BUG_PUBKEYAUTH) {
+       if (datafellows & SSH_BUG_PKSERVICE) {
                buffer_clear(&b);
                buffer_append(&b, session_id2, session_id2_len);
+               skip = session_id2_len;
                buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
-               buffer_put_cstring(&b, server_user);
-               buffer_put_cstring(&b, service);
-               buffer_put_cstring(&b, "publickey");
-               buffer_put_char(&b, 1);
-               buffer_put_cstring(&b, KEX_DSS); 
+               buffer_put_cstring(&b, authctxt->server_user);
+               buffer_put_cstring(&b, authctxt->service);
+               buffer_put_cstring(&b, authctxt->method->name);
+               buffer_put_char(&b, have_sig);
+               if (!(datafellows & SSH_BUG_PKAUTH))
+                       buffer_put_cstring(&b, key_ssh_name(k));
                buffer_put_string(&b, blob, bloblen);
        }
        xfree(blob);
+
        /* append signature */
        buffer_put_string(&b, signature, slen);
        xfree(signature);
 
        /* skip session id and packet type */
        if (buffer_len(&b) < skip + 1)
-               fatal("ssh2_try_pubkey: internal error");
+               fatal("userauth_pubkey: internal error");
        buffer_consume(&b, skip + 1);
 
        /* put remaining data from buffer into packet */
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_raw(buffer_ptr(&b), buffer_len(&b));
        buffer_free(&b);
-
-       /* send */
        packet_send();
-       packet_write_wait();
 
        return 1;
 }
 
-int
-ssh2_try_pubkey(char *filename,
-    const char *server_user, const char *host, const char *service)
+static int
+send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback,
+    int hint)
 {
-       Key *k;
-       int ret = 0;
-       struct stat st;
+       u_char *blob;
+       u_int bloblen, have_sig = 0;
 
-       if (stat(filename, &st) != 0) {
-               debug("key does not exist: %s", filename);
+       debug3("send_pubkey_test");
+
+       if (key_to_blob(k, &blob, &bloblen) == 0) {
+               /* we cannot handle this key */
+               debug3("send_pubkey_test: cannot handle key");
                return 0;
        }
-       debug("try pubkey: %s", filename);
+       /* register callback for USERAUTH_PK_OK message */
+       authctxt->last_key_sign = sign_callback;
+       authctxt->last_key_hint = hint;
+       authctxt->last_key = k;
+       dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
 
-       k = key_new(KEY_DSA);
-       if (!load_private_key(filename, "", k, NULL)) {
-               int success = 0;
-               char *passphrase;
-               char prompt[300];
+       packet_start(SSH2_MSG_USERAUTH_REQUEST);
+       packet_put_cstring(authctxt->server_user);
+       packet_put_cstring(authctxt->service);
+       packet_put_cstring(authctxt->method->name);
+       packet_put_char(have_sig);
+       if (!(datafellows & SSH_BUG_PKAUTH))
+               packet_put_cstring(key_ssh_name(k));
+       packet_put_string(blob, bloblen);
+       xfree(blob);
+       packet_send();
+       return 1;
+}
+
+static Key *
+load_identity_file(char *filename)
+{
+       Key *private;
+       char prompt[300], *passphrase;
+       int quit, i;
+       struct stat st;
+
+       if (stat(filename, &st) < 0) {
+               debug3("no such identity: %s", filename);
+               return NULL;
+       }
+       private = key_load_private_type(KEY_UNSPEC, filename, "", NULL);
+       if (private == NULL) {
+               if (options.batch_mode)
+                       return NULL;
                snprintf(prompt, sizeof prompt,
-                    "Enter passphrase for DSA key '%.100s': ",
-                    filename);
-               passphrase = read_passphrase(prompt, 0);
-               success = load_private_key(filename, passphrase, k, NULL);
-               memset(passphrase, 0, strlen(passphrase));
-               xfree(passphrase);
-               if (!success) {
-                       key_free(k);
-                       return 0;
+                   "Enter passphrase for key '%.100s': ", filename);
+               for (i = 0; i < options.number_of_password_prompts; i++) {
+                       passphrase = read_passphrase(prompt, 0);
+                       if (strcmp(passphrase, "") != 0) {
+                               private = key_load_private_type(KEY_UNSPEC, filename,
+                                   passphrase, NULL);
+                               quit = 0;
+                       } else {
+                               debug2("no passphrase given, try next key");
+                               quit = 1;
+                       }
+                       memset(passphrase, 0, strlen(passphrase));
+                       xfree(passphrase);
+                       if (private != NULL || quit)
+                               break;
+                       debug2("bad passphrase given, try again...");
                }
        }
-       ret = ssh2_sign_and_send_pubkey(k, dsa_sign, server_user, host, service);
-       key_free(k);
-       return ret;
+       return private;
 }
 
-int agent_sign(
-    Key *key,
-    unsigned char **sigp, int *lenp,
-    unsigned char *data, int datalen)
+static int
+identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
 {
-       int ret = -1;
-       AuthenticationConnection *ac = ssh_get_authentication_connection();
-       if (ac != NULL) {
-               ret = ssh_agent_sign(ac, key, sigp, lenp, data, datalen);
-               ssh_close_authentication_connection(ac);
-       }
+       Key *private;
+       int idx, ret;
+
+       idx = authctxt->last_key_hint;
+       if (idx < 0)
+               return -1;
+
+       /* private key is stored in external hardware */
+       if (options.identity_keys[idx]->flags & KEY_FLAG_EXT)
+               return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen);
+
+       private = load_identity_file(options.identity_files[idx]);
+       if (private == NULL)
+               return -1;
+       ret = key_sign(private, sigp, lenp, data, datalen);
+       key_free(private);
        return ret;
 }
 
-int
-ssh2_try_agent(AuthenticationConnection *ac,
-    const char *server_user, const char *host, const char *service)
+static int
+agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
+{
+       return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen);
+}
+
+static int
+key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
+{
+       return key_sign(key, sigp, lenp, data, datalen);
+}
+
+static int
+userauth_pubkey_agent(Authctxt *authctxt)
 {
        static int called = 0;
+       int ret = 0;
        char *comment;
        Key *k;
-       int ret;
 
        if (called == 0) {
-               k = ssh_get_first_identity(ac, &comment, 2);
-               called ++;
+               if (ssh_get_num_identities(authctxt->agent, 2) == 0)
+                       debug2("userauth_pubkey_agent: no keys at all");
+               called = 1;
+       }
+       k = ssh_get_next_identity(authctxt->agent, &comment, 2);
+       if (k == NULL) {
+               debug2("userauth_pubkey_agent: no more keys");
        } else {
-               k = ssh_get_next_identity(ac, &comment, 2);
+               debug("Offering agent key: %s", comment);
+               xfree(comment);
+               ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1);
+               if (ret == 0)
+                       key_free(k);
        }
-       if (k == NULL)
-               return 0;
-       debug("trying DSA agent key %s", comment);
-       xfree(comment);
-       ret = ssh2_sign_and_send_pubkey(k, agent_sign, server_user, host, service);
-       key_free(k);
+       if (ret == 0)
+               debug2("userauth_pubkey_agent: no message sent");
        return ret;
 }
 
+int
+userauth_pubkey(Authctxt *authctxt)
+{
+       static int idx = 0;
+       int sent = 0;
+       Key *key;
+       char *filename;
+
+       if (authctxt->agent != NULL) {
+               do {
+                       sent = userauth_pubkey_agent(authctxt);
+               } while (!sent && authctxt->agent->howmany > 0);
+       }
+       while (!sent && idx < options.num_identity_files) {
+               key = options.identity_keys[idx];
+               filename = options.identity_files[idx];
+               if (key == NULL) {
+                       debug("Trying private key: %s", filename);
+                       key = load_identity_file(filename);
+                       if (key != NULL) {
+                               sent = sign_and_send_pubkey(authctxt, key,
+                                   key_sign_cb);
+                               key_free(key);
+                       }
+               } else if (key->type != KEY_RSA1) {
+                       debug("Offering public key: %s", filename);
+                       sent = send_pubkey_test(authctxt, key,
+                           identity_sign_cb, idx);
+               }
+               idx++;
+       }
+       return sent;
+}
+
+/*
+ * Send userauth request message specifying keyboard-interactive method.
+ */
+int
+userauth_kbdint(Authctxt *authctxt)
+{
+       static int attempt = 0;
+
+       if (attempt++ >= options.number_of_password_prompts)
+               return 0;
+       /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
+       if (attempt > 1 && !authctxt->info_req_seen) {
+               debug3("userauth_kbdint: disable: no info_req_seen");
+               dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
+               return 0;
+       }
+
+       debug2("userauth_kbdint");
+       packet_start(SSH2_MSG_USERAUTH_REQUEST);
+       packet_put_cstring(authctxt->server_user);
+       packet_put_cstring(authctxt->service);
+       packet_put_cstring(authctxt->method->name);
+       packet_put_cstring("");                                 /* lang */
+       packet_put_cstring(options.kbd_interactive_devices ?
+           options.kbd_interactive_devices : "");
+       packet_send();
+
+       dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
+       return 1;
+}
+
+/*
+ * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
+ */
 void
-ssh_userauth2(const char *server_user, char *host)
+input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
 {
-       AuthenticationConnection *ac = ssh_get_authentication_connection();
-       int type;
-       int plen;
-       int sent;
-       unsigned int dlen;
-       int partial;
-       int i = 0;
-       char *auths;
-       char *service = "ssh-connection";               /* service name */
+       Authctxt *authctxt = ctxt;
+       char *name, *inst, *lang, *prompt, *response;
+       u_int num_prompts, i;
+       int echo = 0;
 
-       debug("send SSH2_MSG_SERVICE_REQUEST");
-       packet_start(SSH2_MSG_SERVICE_REQUEST);
-       packet_put_cstring("ssh-userauth");
+       debug2("input_userauth_info_req");
+
+       if (authctxt == NULL)
+               fatal("input_userauth_info_req: no authentication context");
+
+       authctxt->info_req_seen = 1;
+
+       name = packet_get_string(NULL);
+       inst = packet_get_string(NULL);
+       lang = packet_get_string(NULL);
+       if (strlen(name) > 0)
+               log("%s", name);
+       if (strlen(inst) > 0)
+               log("%s", inst);
+       xfree(name);
+       xfree(inst);
+       xfree(lang);
+
+       num_prompts = packet_get_int();
+       /*
+        * Begin to build info response packet based on prompts requested.
+        * We commit to providing the correct number of responses, so if
+        * further on we run into a problem that prevents this, we have to
+        * be sure and clean this up and send a correct error response.
+        */
+       packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+       packet_put_int(num_prompts);
+
+       debug2("input_userauth_info_req: num_prompts %d", num_prompts);
+       for (i = 0; i < num_prompts; i++) {
+               prompt = packet_get_string(NULL);
+               echo = packet_get_char();
+
+               response = read_passphrase(prompt, echo ? RP_ECHO : 0);
+
+               packet_put_cstring(response);
+               memset(response, 0, strlen(response));
+               xfree(response);
+               xfree(prompt);
+       }
+       packet_check_eom(); /* done with parsing incoming message. */
+
+       packet_add_padding(64);
        packet_send();
-       packet_write_wait();
+}
 
-       type = packet_read(&plen);
-       if (type != SSH2_MSG_SERVICE_ACCEPT) {
-               fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
+static int
+ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
+    u_char *data, u_int datalen)
+{
+       Buffer b;
+       struct stat st;
+       pid_t pid;
+       int to[2], from[2], status, version = 2;
+
+       debug2("ssh_keysign called");
+
+       if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
+               error("ssh_keysign: no installed: %s", strerror(errno));
+               return -1;
        }
-       if (packet_remaining() > 0) {
-               char *reply = packet_get_string(&plen);
-               debug("service_accept: %s", reply);
-               xfree(reply);
-       } else {
-               /* payload empty for ssh-2.0.13 ?? */
-               debug("buggy server: service_accept w/o service");
+       if (fflush(stdout) != 0)
+               error("ssh_keysign: fflush: %s", strerror(errno));
+       if (pipe(to) < 0) {
+               error("ssh_keysign: pipe: %s", strerror(errno));
+               return -1;
+       }
+       if (pipe(from) < 0) {
+               error("ssh_keysign: pipe: %s", strerror(errno));
+               return -1;
+       }
+       if ((pid = fork()) < 0) {
+               error("ssh_keysign: fork: %s", strerror(errno));
+               return -1;
+       }
+       if (pid == 0) {
+               seteuid(getuid());
+               setuid(getuid());
+               close(from[0]);
+               if (dup2(from[1], STDOUT_FILENO) < 0)
+                       fatal("ssh_keysign: dup2: %s", strerror(errno));
+               close(to[1]);
+               if (dup2(to[0], STDIN_FILENO) < 0)
+                       fatal("ssh_keysign: dup2: %s", strerror(errno));
+               close(from[1]);
+               close(to[0]);
+               execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
+               fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
+                   strerror(errno));
+       }
+       close(from[1]);
+       close(to[0]);
+
+       buffer_init(&b);
+       buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
+       buffer_put_string(&b, data, datalen);
+       ssh_msg_send(to[1], version, &b);
+
+       if (ssh_msg_recv(from[0], &b) < 0) {
+               error("ssh_keysign: no reply");
+               buffer_clear(&b);
+               return -1;
+       }
+       close(from[0]);
+       close(to[1]);
+
+       while (waitpid(pid, &status, 0) < 0)
+               if (errno != EINTR)
+                       break;
+
+       if (buffer_get_char(&b) != version) {
+               error("ssh_keysign: bad version");
+               buffer_clear(&b);
+               return -1;
        }
-       packet_done();
-       debug("got SSH2_MSG_SERVICE_ACCEPT");
+       *sigp = buffer_get_string(&b, lenp);
+       buffer_clear(&b);
 
-       /* INITIAL request for auth */
+       return 0;
+}
+
+int
+userauth_hostbased(Authctxt *authctxt)
+{
+       Key *private = NULL;
+       Sensitive *sensitive = authctxt->sensitive;
+       Buffer b;
+       u_char *signature, *blob;
+       char *chost, *pkalg, *p;
+       const char *service;
+       u_int blen, slen;
+       int ok, i, len, found = 0;
+
+       /* check for a useful key */
+       for (i = 0; i < sensitive->nkeys; i++) {
+               private = sensitive->keys[i];
+               if (private && private->type != KEY_RSA1) {
+                       found = 1;
+                       /* we take and free the key */
+                       sensitive->keys[i] = NULL;
+                       break;
+               }
+       }
+       if (!found) {
+               debug("No more client hostkeys for hostbased authentication.");
+               return 0;
+       }
+       if (key_to_blob(private, &blob, &blen) == 0) {
+               key_free(private);
+               return 0;
+       }
+       /* figure out a name for the client host */
+       p = get_local_name(packet_get_connection_in());
+       if (p == NULL) {
+               error("userauth_hostbased: cannot get local ipaddr/name");
+               key_free(private);
+               return 0;
+       }
+       len = strlen(p) + 2;
+       chost = xmalloc(len);
+       strlcpy(chost, p, len);
+       strlcat(chost, ".", len);
+       debug2("userauth_hostbased: chost %s", chost);
+       xfree(p);
+
+       service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
+           authctxt->service;
+       pkalg = xstrdup(key_ssh_name(private));
+       buffer_init(&b);
+       /* construct data */
+       buffer_put_string(&b, session_id2, session_id2_len);
+       buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
+       buffer_put_cstring(&b, authctxt->server_user);
+       buffer_put_cstring(&b, service);
+       buffer_put_cstring(&b, authctxt->method->name);
+       buffer_put_cstring(&b, pkalg);
+       buffer_put_string(&b, blob, blen);
+       buffer_put_cstring(&b, chost);
+       buffer_put_cstring(&b, authctxt->local_user);
+#ifdef DEBUG_PK
+       buffer_dump(&b);
+#endif
+       if (sensitive->external_keysign)
+               ok = ssh_keysign(private, &signature, &slen,
+                   buffer_ptr(&b), buffer_len(&b));
+       else
+               ok = key_sign(private, &signature, &slen,
+                   buffer_ptr(&b), buffer_len(&b));
+       key_free(private);
+       buffer_free(&b);
+       if (ok != 0) {
+               error("key_sign failed");
+               xfree(chost);
+               xfree(pkalg);
+               return 0;
+       }
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
-       packet_put_cstring(server_user);
-       packet_put_cstring(service);
-       packet_put_cstring("none");
+       packet_put_cstring(authctxt->server_user);
+       packet_put_cstring(authctxt->service);
+       packet_put_cstring(authctxt->method->name);
+       packet_put_cstring(pkalg);
+       packet_put_string(blob, blen);
+       packet_put_cstring(chost);
+       packet_put_cstring(authctxt->local_user);
+       packet_put_string(signature, slen);
+       memset(signature, 's', slen);
+       xfree(signature);
+       xfree(chost);
+       xfree(pkalg);
+
        packet_send();
-       packet_write_wait();
+       return 1;
+}
+
+/* find auth method */
+
+/*
+ * given auth method name, if configurable options permit this method fill
+ * in auth_ident field and return true, otherwise return false.
+ */
+static int
+authmethod_is_enabled(Authmethod *method)
+{
+       if (method == NULL)
+               return 0;
+       /* return false if options indicate this method is disabled */
+       if  (method->enabled == NULL || *method->enabled == 0)
+               return 0;
+       /* return false if batch mode is enabled but method needs interactive mode */
+       if  (method->batch_flag != NULL && *method->batch_flag != 0)
+               return 0;
+       return 1;
+}
+
+static Authmethod *
+authmethod_lookup(const char *name)
+{
+       Authmethod *method = NULL;
+       if (name != NULL)
+               for (method = authmethods; method->name != NULL; method++)
+                       if (strcmp(name, method->name) == 0)
+                               return method;
+       debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
+       return NULL;
+}
+
+/* XXX internal state */
+static Authmethod *current = NULL;
+static char *supported = NULL;
+static char *preferred = NULL;
+
+/*
+ * Given the authentication method list sent by the server, return the
+ * next method we should try.  If the server initially sends a nil list,
+ * use a built-in default list.
+ */
+static Authmethod *
+authmethod_get(char *authlist)
+{
+       char *name = NULL;
+       u_int next;
+
+       /* Use a suitable default if we're passed a nil list.  */
+       if (authlist == NULL || strlen(authlist) == 0)
+               authlist = options.preferred_authentications;
+
+       if (supported == NULL || strcmp(authlist, supported) != 0) {
+               debug3("start over, passed a different list %s", authlist);
+               if (supported != NULL)
+                       xfree(supported);
+               supported = xstrdup(authlist);
+               preferred = options.preferred_authentications;
+               debug3("preferred %s", preferred);
+               current = NULL;
+       } else if (current != NULL && authmethod_is_enabled(current))
+               return current;
 
        for (;;) {
-               sent = 0;
-               type = packet_read(&plen);
-               if (type == SSH2_MSG_USERAUTH_SUCCESS)
-                       break;
-               if (type != SSH2_MSG_USERAUTH_FAILURE)
-                       fatal("access denied: %d", type);
-               /* SSH2_MSG_USERAUTH_FAILURE means: try again */
-               auths = packet_get_string(&dlen);
-               debug("authentications that can continue: %s", auths);
-               partial = packet_get_char();
-               packet_done();
-               if (partial)
-                       debug("partial success");
-               if (options.dsa_authentication &&
-                   strstr(auths, "publickey") != NULL) {
-                       if (ac != NULL)
-                               sent = ssh2_try_agent(ac,
-                                   server_user, host, service);
-                       if (!sent) {
-                               while (i < options.num_identity_files2) {
-                                       sent = ssh2_try_pubkey(
-                                           options.identity_files2[i++],
-                                           server_user, host, service);
-                                       if (sent)
-                                               break;
-                               }
-                       }
+               if ((name = match_list(preferred, supported, &next)) == NULL) {
+                       debug("No more authentication methods to try.");
+                       current = NULL;
+                       return NULL;
                }
-               if (!sent) {
-                       if (options.password_authentication &&
-                           !options.batch_mode &&
-                           strstr(auths, "password") != NULL) {
-                               sent = ssh2_try_passwd(server_user, host, service);
-                       }
+               preferred += next;
+               debug3("authmethod_lookup %s", name);
+               debug3("remaining preferred: %s", preferred);
+               if ((current = authmethod_lookup(name)) != NULL &&
+                   authmethod_is_enabled(current)) {
+                       debug3("authmethod_is_enabled %s", name);
+                       debug("Next authentication method: %s", name);
+                       return current;
                }
-               if (!sent)
-                       fatal("Permission denied (%s).", auths);
-               xfree(auths);
-       }
-       if (ac != NULL)
-               ssh_close_authentication_connection(ac);
-       packet_done();
-       debug("ssh-userauth2 successfull");
+       }
+}
+
+static char *
+authmethods_get(void)
+{
+       Authmethod *method = NULL;
+       Buffer b;
+       char *list;
+
+       buffer_init(&b);
+       for (method = authmethods; method->name != NULL; method++) {
+               if (authmethod_is_enabled(method)) {
+                       if (buffer_len(&b) > 0)
+                               buffer_append(&b, ",", 1);
+                       buffer_append(&b, method->name, strlen(method->name));
+               }
+       }
+       buffer_append(&b, "\0", 1);
+       list = xstrdup(buffer_ptr(&b));
+       buffer_free(&b);
+       return list;
 }
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