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dns: trim response immediately before the write 

Previously the response was being trimmed before adding the EDNS values, which could cause it to exceed
the max size.
pull/10009/head
Daniel Nephin 2021-04-13 17:48:29 -04:00
parent 436a02af31
commit 42f7963252
2 changed files with 4 additions and 7 deletions
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10
agent/dns.go
View File

@ -507,7 +507,7 @@ func (d *DNSServer) handleQuery(resp dns.ResponseWriter, req *dns.Msg) {
setEDNS(req, m, !errors.Is(err, errECSNotGlobal))
//d.trimDNSResponse(cfg, network, req, m)
d.trimDNSResponse(cfg, network, req, m)
if err := resp.WriteMsg(m); err != nil {
d.logger.Warn("failed to respond", "error", err)
@ -1270,10 +1270,8 @@ func (d *DNSServer) serviceLookup(cfg *dnsConfig, lookup serviceLookup, req, res
d.serviceNodeRecords(cfg, lookup.Datacenter, out.Nodes, req, resp, ttl, lookup.MaxRecursionLevel)
}
d.trimDNSResponse(cfg, lookup.Network, req, resp)
// If the answer is empty and the response isn't truncated, return not found
if len(resp.Answer) == 0 && !resp.Truncated {
if len(resp.Answer) == 0 {
return errNoAnswer
}
return nil
@ -1378,10 +1376,8 @@ func (d *DNSServer) preparedQueryLookup(cfg *dnsConfig, network, datacenter, que
d.serviceNodeRecords(cfg, out.Datacenter, out.Nodes, req, resp, ttl, maxRecursionLevel)
}
d.trimDNSResponse(cfg, network, req, resp)
// If the answer is empty and the response isn't truncated, return not found
if len(resp.Answer) == 0 && !resp.Truncated {
if len(resp.Answer) == 0 {
return errNoAnswer
}
return nil

1
agent/dns_test.go
View File

@ -545,6 +545,7 @@ func TestDNS_NodeLookup_CNAME(t *testing.T) {
m := new(dns.Msg)
m.SetQuestion("google.node.consul.", dns.TypeANY)
m.SetEdns0(8192, true)
c := new(dns.Client)
in, _, err := c.Exchange(m, a.DNSAddr())