dns64: Fall back to plain AAAA query with synthall but no A records

Networks which only have tunneled IPv6 access but still want to go
IPv6-only internally can use unbound's DNS64 module together with the
dns64-synthall or dns64-ignore-aaaa options to direct most traffic (any
dualstack domain) to their NAT64.

There is only one problem with this setup, currently domains with only AAAA
records will fail to resolve.

To allow for this use-case arrange for the A sub-query to make the AAAA
super query advance along the module stack when no records are returned.

Signed-off-by: Daniel Gröber <dxld@darkboxed.org>
This commit is contained in:
Daniel Gröber via Unbound-users 2023-10-09 14:46:35 +02:00 committed by George Thessalonikefs
parent dd086e5bfd
commit c1e5e6781e

View file

@ -982,6 +982,17 @@ dns64_inform_super(struct module_qstate* qstate, int id,
return; return;
} }
/* When no A record is found for synthesis fall back to AAAA again. */
if (qstate->qinfo.qtype == LDNS_RR_TYPE_A &&
qstate->return_rcode == LDNS_RCODE_NOERROR &&
!( qstate->return_msg &&
qstate->return_msg->rep &&
reply_find_answer_rrset(&qstate->qinfo, qstate->return_msg->rep)))
{
super_dq->state = DNS64_INTERNAL_QUERY;
return;
}
/* Use return code from A query in response to client. */ /* Use return code from A query in response to client. */
if (super->return_rcode != LDNS_RCODE_NOERROR) if (super->return_rcode != LDNS_RCODE_NOERROR)
super->return_rcode = qstate->return_rcode; super->return_rcode = qstate->return_rcode;