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open-consul
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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.
This commit is contained in:
Daniel Nephin 2021-04-13 17:48:29 -04:00
parent a9e9c6c23e
commit 4712e24749
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())