1 files changed, 63 insertions, 2 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
index 1a03c6bf3..aaf02ece4 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.183 2010/04/26 22:28:24 djm Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.186 2010/11/29 23:45:51 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -69,6 +69,7 @@
 #include "msg.h"
 #include "pathnames.h"
 #include "uidswap.h"
+#include "hostfile.h"
 #include "schnorr.h"
 #include "jpake.h"
 
@@ -101,8 +102,60 @@ verify_host_key_callback(Key *hostkey)
         return 0;
 }
 
+static char *
+order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
+{
+        char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
+        size_t maxlen;
+        struct hostkeys *hostkeys;
+        int ktype;
+
+        /* Find all hostkeys for this hostname */
+        get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
+        hostkeys = init_hostkeys();
+        load_hostkeys(hostkeys, hostname, options.user_hostfile2);
+        load_hostkeys(hostkeys, hostname, options.system_hostfile2);
+        load_hostkeys(hostkeys, hostname, options.user_hostfile);
+        load_hostkeys(hostkeys, hostname, options.system_hostfile);
+
+        oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
+        maxlen = strlen(avail) + 1;
+        first = xmalloc(maxlen);
+        last = xmalloc(maxlen);
+        *first = *last = '\0';
+
+#define ALG_APPEND(to, from) \
+        do { \
+                if (*to != '\0') \
+                        strlcat(to, ",", maxlen); \
+                strlcat(to, from, maxlen); \
+        } while (0)
+
+        while ((alg = strsep(&avail, ",")) && *alg != '\0') {
+                if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
+                        fatal("%s: unknown alg %s", __func__, alg);
+                if (lookup_key_in_hostkeys_by_type(hostkeys,
+                    key_type_plain(ktype), NULL))
+                        ALG_APPEND(first, alg);
+                else
+                        ALG_APPEND(last, alg);
+        }
+#undef ALG_APPEND
+        xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
+        if (*first != '\0')
+                debug3("%s: prefer hostkeyalgs: %s", __func__, first);
+
+        xfree(first);
+        xfree(last);
+        xfree(hostname);
+        xfree(oavail);
+        free_hostkeys(hostkeys);
+
+        return ret;
+}
+
 void
-ssh_kex2(char *host, struct sockaddr *hostaddr)
+ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
 {
         Kex *kex;
 
@@ -160,6 +213,13 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
         if (options.hostkeyalgorithms != NULL)
                 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
                     options.hostkeyalgorithms;
+        else {
+                /* Prefer algorithms that we already have keys for */
+                myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
+                    order_hostkeyalgs(host, hostaddr, port);
+        }
+        if (options.kex_algorithms != NULL)
+                myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
 
 #ifdef GSSAPI
         /* If we've got GSSAPI algorithms, then we also support the
@@ -181,6 +241,7 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
         kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
         kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
+        kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
 #ifdef GSSAPI
         if (options.gss_keyex) {
                 kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client;