SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

resolved: fully follow CNAMEs in the DNS stub after all

Browse Source 
In 2f4d8e577c I argued that following
CNAMEs in the stub is not necessary anymore. However, I think it' better
to revert to the status quo ante and follow it after all, given it is
easy for us and makes sure our D-Bus/varlink replies are more similar to
our DNS stub replies that way, and we save clients potential roundtrips.

Hence, whenever we hit a CNAME/DNAME redirect, let's restart the query
like we do for the D-Bus/Varlink case, and collect replies as we go.
This commit is contained in:
Lennart Poettering
2021-03-06 14:04:21 +01:00
parent 39005e1870
commit b97fc57178
1 changed files with 27 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/resolve/resolved-dns-stub.c
+27 -11
View File
@@ -586,13 +586,6 @@ static int dns_stub_send_reply(
edns0_do = dns_stub_reply_with_edns0_do(q); /* let's check if we shall reply with EDNS0 DO? */
r = dns_stub_assign_sections(
q,
q->request_packet->question,
edns0_do);
if (r < 0)
return log_debug_errno(r, "Failed to assign sections: %m");
r = dns_stub_make_reply_packet(
&reply,
DNS_PACKET_PAYLOAD_SIZE_MAX(q->request_packet),
@@ -743,13 +736,37 @@ static void dns_stub_query_complete(DnsQuery *q) {
}
}
/* Note that we don't bother with following CNAMEs here. We propagate the authoritative/additional
* sections from the upstream answer however, hence if the upstream server collected that information
* already we don't have to collect it ourselves anymore. */
/* Take all data from the current reply, and merge it into the three reply sections we are building
* up. We do this before processing CNAME redirects, so that we gradually build up our sections, and
* and keep adding all RRs in the CNAME chain. */
r = dns_stub_assign_sections(
q,
q->request_packet->question,
dns_stub_reply_with_edns0_do(q));
if (r < 0) {
log_debug_errno(r, "Failed to assign sections: %m");
dns_query_free(q);
return;
}
switch (q->state) {
case DNS_TRANSACTION_SUCCESS:
r = dns_query_process_cname(q);
if (r == -ELOOP) { /* CNAME loop, let's send what we already have */
log_debug_errno(r, "Detected CNAME loop, returning what we already have.");
(void) dns_stub_send_reply(q, q->answer_rcode);
break;
}
if (r < 0) {
log_debug_errno(r, "Failed to process CNAME: %m");
break;
}
if (r == DNS_QUERY_RESTARTED)
return;
_fallthrough_;
case DNS_TRANSACTION_RCODE_FAILURE:
(void) dns_stub_send_reply(q, q->answer_rcode);
break;
@@ -888,7 +905,6 @@ static void dns_stub_process_query(Manager *m, DnsStubListenerExtra *l, DnsStrea
r = dns_query_new(m, &q, p->question, p->question, NULL, 0,
SD_RESOLVED_PROTOCOLS_ALL|
SD_RESOLVED_NO_SEARCH|
SD_RESOLVED_NO_CNAME|
(DNS_PACKET_DO(p) ? SD_RESOLVED_REQUIRE_PRIMARY : 0)|
SD_RESOLVED_CLAMP_TTL);
if (r < 0) {