From 63772f7ac43b5ebdbc4897cb8e909b929ca257c8 Mon Sep 17 00:00:00 2001 From: Daniel Nephin Date: Fri, 16 Jul 2021 12:34:27 -0400 Subject: [PATCH] dns: improve naming of error to match DNS terminology Co-authored-by: Blake Covarrubias --- agent/dns.go | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/agent/dns.go b/agent/dns.go index 48f08b71d..e14d289a8 100644 --- a/agent/dns.go +++ b/agent/dns.go @@ -498,7 +498,7 @@ func (d *DNSServer) handleQuery(resp dns.ResponseWriter, req *dns.Msg) { default: err = d.dispatch(resp.RemoteAddr(), req, m, maxRecursionLevelDefault) rCode := rCodeFromError(err) - if rCode == dns.RcodeNameError || errors.Is(err, errNoAnswer) { + if rCode == dns.RcodeNameError || errors.Is(err, errNoData) { d.addSOA(cfg, m) } m.SetRcode(req, rCode) @@ -610,9 +610,11 @@ func (d *DNSServer) parseDatacenter(labels []string, datacenter *string) bool { var errECSNotGlobal = fmt.Errorf("ECS response is not global") var errNameNotFound = fmt.Errorf("DNS name not found") -// errNoAnswer is used to indicate that the response should set SOA, and the -// success response code. -var errNoAnswer = fmt.Errorf("no DNS Answer") +// errNoData is used to indicate no resource records exist for the specified query type. +// Per the recommendation from Section 2.2 of RFC 2308, the server will return a TYPE 2 +// NODATA response in which the RCODE is set to NOERROR (RcodeSuccess), the Answer +// section is empty, and the Authority section contains the SOA record. +var errNoData = fmt.Errorf("no DNS Answer") // ecsNotGlobalError may be used to wrap an error or nil, to indicate that the // EDNS client subnet source scope is not global. @@ -869,12 +871,12 @@ func (d *DNSServer) trimDomain(query string) string { return strings.TrimSuffix(query, shorter) } -// rCodeFromError return the DNS Error code an error +// rCodeFromError return the appropriate DNS response code for a given error func rCodeFromError(err error) int { switch { case err == nil: return dns.RcodeSuccess - case errors.Is(err, errNoAnswer): + case errors.Is(err, errNoData): return dns.RcodeSuccess case errors.Is(err, errECSNotGlobal): return rCodeFromError(errors.Unwrap(err)) @@ -1272,9 +1274,8 @@ func (d *DNSServer) serviceLookup(cfg *dnsConfig, lookup serviceLookup, req, res d.serviceNodeRecords(cfg, lookup.Datacenter, out.Nodes, req, resp, ttl, lookup.MaxRecursionLevel) } - // If the answer is empty and the response isn't truncated, return not found if len(resp.Answer) == 0 { - return errNoAnswer + return errNoData } return nil } @@ -1378,9 +1379,8 @@ func (d *DNSServer) preparedQueryLookup(cfg *dnsConfig, datacenter, query string d.serviceNodeRecords(cfg, out.Datacenter, out.Nodes, req, resp, ttl, maxRecursionLevel) } - // If the answer is empty and the response isn't truncated, return not found if len(resp.Answer) == 0 { - return errNoAnswer + return errNoData } return nil }