client: Properly reset session structures on disconnect

torture_connect_double  test case used to test the connect only up
to key exchange phase, but not after the new keys are stated to be
used for communication. The keys from previous connectoin were not
cleaned up from the previous invocation as well as the seqence
number was not reset and therefore any further packet was failing
with length-check errors or MAC errors.

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

src/client.c

@@ -667,6 +667,8 @@ void ssh_disconnect(ssh_session session) {
     ssh_socket_close(session->socket);
   }
 error:
+  session->recv_seq = 0;
+  session->send_seq = 0;
   session->alive = 0;
   if (session->socket != NULL){
     ssh_socket_reset(session->socket);
@@ -682,6 +684,13 @@ error:
     crypto_free(session->current_crypto);
     session->current_crypto=NULL;
   }
+  if (session->next_crypto) {
+    crypto_free(session->next_crypto);
+    session->next_crypto = crypto_new();
+    if (session->next_crypto == NULL) {
+      ssh_set_error_oom(session);
+    }
+  }
   if (session->in_buffer) {
     ssh_buffer_reinit(session->in_buffer);
   }