diff --git a/middleware/proxy/dns.go b/middleware/proxy/dns.go index 78a8c3bfe..157d97992 100644 --- a/middleware/proxy/dns.go +++ b/middleware/proxy/dns.go @@ -5,7 +5,6 @@ import ( "net" "time" - "github.com/coredns/coredns/middleware/pkg/singleflight" "github.com/coredns/coredns/request" "github.com/miekg/dns" @@ -13,7 +12,6 @@ import ( type dnsEx struct { Timeout time.Duration - group *singleflight.Group Options } @@ -26,7 +24,7 @@ func newDNSEx() *dnsEx { } func newDNSExWithOption(opt Options) *dnsEx { - return &dnsEx{group: new(singleflight.Group), Timeout: defaultTimeout * time.Second, Options: opt} + return &dnsEx{Timeout: defaultTimeout * time.Second, Options: opt} } func (d *dnsEx) Protocol() string { return "dns" } @@ -65,30 +63,14 @@ func (d *dnsEx) Exchange(ctx context.Context, addr string, state request.Request } func (d *dnsEx) ExchangeConn(m *dns.Msg, co net.Conn) (*dns.Msg, time.Duration, error) { - t := "nop" - if t1, ok := dns.TypeToString[m.Question[0].Qtype]; ok { - t = t1 - } - cl := "nop" - if cl1, ok := dns.ClassToString[m.Question[0].Qclass]; ok { - cl = cl1 - } - start := time.Now() - - // Name needs to be normalized! Bug in go dns. - r, err := d.group.Do(m.Question[0].Name+t+cl, func() (interface{}, error) { - return exchange(m, co) - }) - - r1 := r.(dns.Msg) + r, err := exchange(m, co) rtt := time.Since(start) - return &r1, rtt, err + + return r, rtt, err } -// exchange does *not* return a pointer to dns.Msg because that leads to buffer reuse when -// group.Do is used in Exchange. -func exchange(m *dns.Msg, co net.Conn) (dns.Msg, error) { +func exchange(m *dns.Msg, co net.Conn) (*dns.Msg, error) { opt := m.IsEdns0() udpsize := uint16(dns.MinMsgSize) @@ -109,7 +91,7 @@ func exchange(m *dns.Msg, co net.Conn) (dns.Msg, error) { dnsco.Close() if r == nil { - return dns.Msg{}, err + return nil, err } - return *r, err + return r, err } diff --git a/middleware/proxy/upstream.go b/middleware/proxy/upstream.go index 8bc3e5306..76dd70348 100644 --- a/middleware/proxy/upstream.go +++ b/middleware/proxy/upstream.go @@ -328,6 +328,9 @@ func (u *staticUpstream) Select() *UpstreamHost { if u.Policy == nil { h := (&Random{}).Select(pool) + if h != nil { + return h + } if h == nil && u.Spray == nil { return nil } diff --git a/test/proxy_health_test.go b/test/proxy_health_test.go index 19f8bfdc3..5cf168acb 100644 --- a/test/proxy_health_test.go +++ b/test/proxy_health_test.go @@ -41,3 +41,76 @@ func TestProxyErratic(t *testing.T) { // tests that it times out. p.Lookup(state, "example.org.", dns.TypeA) } + +func TestProxyThreeWay(t *testing.T) { + // Run 3 CoreDNS server, 2 upstream ones and a proxy. 1 Upstream is unhealthy after 1 query, but after + // that we should still be able to send to the other one + log.SetOutput(ioutil.Discard) + + // Backend CoreDNS's. + corefileUp1 := `example.org:0 { + erratic { + drop 2 + } + } +` + + up1, err := CoreDNSServer(corefileUp1) + if err != nil { + t.Fatalf("Could not get CoreDNS serving instance: %s", err) + } + defer up1.Stop() + + corefileUp2 := `example.org:0 { + whoami + } +` + + up2, err := CoreDNSServer(corefileUp2) + if err != nil { + t.Fatalf("Could not get CoreDNS serving instance: %s", err) + } + defer up2.Stop() + + addr1, _ := CoreDNSServerPorts(up1, 0) + if addr1 == "" { + t.Fatalf("Could not get UDP listening port") + } + addr2, _ := CoreDNSServerPorts(up2, 0) + if addr2 == "" { + t.Fatalf("Could not get UDP listening port") + } + + // Proxying CoreDNS. + corefileProxy := `example.org:0 { + proxy . ` + addr1 + " " + addr2 + ` { + max_fails 1 + } + }` + + prx, err := CoreDNSServer(corefileProxy) + if err != nil { + t.Fatalf("Could not get CoreDNS serving instance: %s", err) + } + defer prx.Stop() + addr, _ := CoreDNSServerPorts(prx, 0) + if addr == "" { + t.Fatalf("Could not get UDP listening port") + } + + m := new(dns.Msg) + m.SetQuestion("example.org.", dns.TypeA) + + for i := 0; i < 10; i++ { + r, err := dns.Exchange(m, addr) + if err != nil { + continue + } + // We would previously get SERVFAIL, so just getting answers here + // is a good sign. The actuall timeouts are handled in the err != nil case + // above. + if r.Rcode != dns.RcodeSuccess { + t.Fatalf("Expected success rcode, got %d", r.Rcode) + } + } +}