packet_cb: Properly verify the signature type

Issue reported by Tilo Eckert <tilo.eckert@flam.de>

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

src/packet_cb.c

@@ -194,15 +194,15 @@ SSH_PACKET_CALLBACK(ssh_packet_newkeys){
         goto error;
     }
 
-    /* check if public key from server matches user preferences */
+    /* Check if signature from server matches user preferences */
     if (session->opts.wanted_methods[SSH_HOSTKEYS]) {
-        if(!ssh_match_group(session->opts.wanted_methods[SSH_HOSTKEYS],
-                            server_key->type_c)) {
+        if (!ssh_match_group(session->opts.wanted_methods[SSH_HOSTKEYS],
+                             sig->type_c)) {
             ssh_set_error(session,
                           SSH_FATAL,
                           "Public key from server (%s) doesn't match user "
                           "preference (%s)",
-                          server_key->type_c,
+                          sig->type_c,
                           session->opts.wanted_methods[SSH_HOSTKEYS]);
             goto error;
         }