Fix crash in DHCPv6 information-request handler.

CHANGELOG

@@ -38,6 +38,11 @@ version 2.66
             agent. Thanks to Lakefield Communications for providing a
             bounty for this addition.
  
+	    Fixed crash, introduced in 2.64, whilst handling DHCPv6
+	    information-requests with some common configurations.
+	    Thanks to Robert M. Albrecht for the bug report and 
+	    chasing the problem.
+
 
 version 2.65
 	    Fix regression which broke forwarding of queries sent via

src/rfc3315.c

@@ -1027,7 +1027,7 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
       {
 	/* We can't discriminate contexts based on address, as we don't know it.
 	   If there is only one possible context, we can use its tags */
-	if (context && !context->current)
+	if (context && context->netid.net && !context->current)
 	  {
 	    context->netid.next = NULL;
 	    context_tags =  &context->netid;