Re: Bug with HMAC negotation in 1.0.5

[Niels Möller]

[EMAIL PROTECTED] (Niels Möller) writes:

> "Joseph Galbraith" <[EMAIL PROTECTED]> writes:
> 
> > In our configuration of lsh, the lsh client send
> > "hmac-sha1,hmac-md5"
> > 
> > Our server sends "hmac-md5,hmac-sha1,none".
> > 
> > In this case, lsh is electing to go with
> > hmac-md5, which I believe is incorrect.
> 
> [...]
> 
> > It appears that the first algorithm on the client's (lsh, in this case)
> > list should be chosen, which would result in "hmac-sha1" being used.
> 
> It definitely should. Thanks for the bug report.

Here's a patch that you can try out; the first hunk is the important
one, the rest is cosmetics.

diff -u -a -r1.71 keyexchange.c
--- keyexchange.c       2000/09/14 23:44:40     1.71
+++ keyexchange.c       2000/10/01 18:57:49
@@ -178,11 +178,11 @@
 }

 static int
-select_algorithm(struct int_list *server_list,
-                struct int_list *client_list)
+select_algorithm(struct int_list *client_list,
+                struct int_list *server_list)
 {
   /* FIXME: This quadratic complexity algorithm should do as long as
-   * the lists are short. To avoid DOS-attacks, ther should probably
+   * the lists are short. To avoid DOS-attacks, there should probably
    * be some limit on the list lengths. */
   unsigned i, j;

@@ -272,11 +272,13 @@
   /* Select key exchange algorithms */

   /* FIXME: Look at the hostkey algorithm as well. */
-  if (LIST(connection->kexinits[0]->kex_algorithms)[0]
-      == LIST(connection->kexinits[1]->kex_algorithms)[0])
+  if (LIST(connection->kexinits[CONNECTION_CLIENT]->kex_algorithms)[0]
+      == LIST(connection->kexinits[CONNECTION_SERVER]->kex_algorithms)[0])
     {
       /* Use this algorithm */
-      kex_algorithm_atom = LIST(connection->kexinits[0]->kex_algorithms)[0];
+      kex_algorithm_atom
+       = LIST(connection->kexinits[CONNECTION_CLIENT]->kex_algorithms)[0];
+
       connection->kex_state = KEX_STATE_IN_PROGRESS;
     }
   else
@@ -291,8 +293,8 @@
        * certain features of the host key algorithms. */

       kex_algorithm_atom
-       = select_algorithm(connection->kexinits[0]->kex_algorithms,
-                          connection->kexinits[1]->kex_algorithms);
+       = select_algorithm(connection->kexinits[CONNECTION_CLIENT]->kex_algorithms,
+                          connection->kexinits[CONNECTION_SERVER]->kex_algorithms);
       
       /* FIXME: This is actually ok for SRP. */
       if  (!kex_algorithm_atom)
@@ -304,8 +306,8 @@
     }

   hostkey_algorithm_atom
-    = select_algorithm(connection->kexinits[0]->server_hostkey_algorithms,
-                      connection->kexinits[1]->server_hostkey_algorithms);
+    = 
+select_algorithm(connection->kexinits[CONNECTION_CLIENT]->server_hostkey_algorithms,
+                      
+connection->kexinits[CONNECTION_SERVER]->server_hostkey_algorithms);

   if (!hostkey_algorithm_atom)
     {
@@ -320,8 +322,8 @@
   for(i = 0; i<KEX_PARAMETERS; i++)
     {
       parameters[i]
-       = select_algorithm(connection->kexinits[0]->parameters[i],
-                          connection->kexinits[1]->parameters[i]);
+       = select_algorithm(connection->kexinits[CONNECTION_CLIENT]->parameters[i],
+                          connection->kexinits[CONNECTION_SERVER]->parameters[i]);

       if (!parameters[i])
        {