1 files changed, 131 insertions, 68 deletions

diff --git a/vendor/github.com/miekg/dns/server.go b/vendor/github.com/miekg/dns/server.go
index 685753f43..2d98f1488 100644
--- a/vendor/github.com/miekg/dns/server.go
+++ b/vendor/github.com/miekg/dns/server.go
@@ -9,12 +9,19 @@ import (
 	"io"
 	"net"
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
-// Maximum number of TCP queries before we close the socket.
+// Default maximum number of TCP queries before we close the socket.
 const maxTCPQueries = 128
 
+// Interval for stop worker if no load
+const idleWorkerTimeout = 10 * time.Second
+
+// Maximum number of workers
+const maxWorkersCount = 10000
+
 // Handler is implemented by any value that implements ServeDNS.
 type Handler interface {
 	ServeDNS(w ResponseWriter, r *Msg)
@@ -43,6 +50,7 @@ type ResponseWriter interface {
 }
 
 type response struct {
+	msg            []byte
 	hijacked       bool // connection has been hijacked by handler
 	tsigStatus     error
 	tsigTimersOnly bool
@@ -51,7 +59,6 @@ type response struct {
 	udp            *net.UDPConn      // i/o connection if UDP was used
 	tcp            net.Conn          // i/o connection if TCP was used
 	udpSession     *SessionUDP       // oob data to get egress interface right
-	remoteAddr     net.Addr          // address of the client
 	writer         Writer            // writer to output the raw DNS bits
 }
 
@@ -296,12 +303,63 @@ type Server struct {
 	DecorateReader DecorateReader
 	// DecorateWriter is optional, allows customization of the process that writes raw DNS messages.
 	DecorateWriter DecorateWriter
+	// Maximum number of TCP queries before we close the socket. Default is maxTCPQueries (unlimited if -1).
+	MaxTCPQueries int
 
+	// UDP packet or TCP connection queue
+	queue chan *response
+	// Workers count
+	workersCount int32
 	// Shutdown handling
 	lock    sync.RWMutex
 	started bool
 }
 
+func (srv *Server) worker(w *response) {
+	srv.serve(w)
+
+	for {
+		count := atomic.LoadInt32(&srv.workersCount)
+		if count > maxWorkersCount {
+			return
+		}
+		if atomic.CompareAndSwapInt32(&srv.workersCount, count, count+1) {
+			break
+		}
+	}
+
+	defer atomic.AddInt32(&srv.workersCount, -1)
+
+	inUse := false
+	timeout := time.NewTimer(idleWorkerTimeout)
+	defer timeout.Stop()
+LOOP:
+	for {
+		select {
+		case w, ok := <-srv.queue:
+			if !ok {
+				break LOOP
+			}
+			inUse = true
+			srv.serve(w)
+		case <-timeout.C:
+			if !inUse {
+				break LOOP
+			}
+			inUse = false
+			timeout.Reset(idleWorkerTimeout)
+		}
+	}
+}
+
+func (srv *Server) spawnWorker(w *response) {
+	select {
+	case srv.queue <- w:
+	default:
+		go srv.worker(w)
+	}
+}
+
 // ListenAndServe starts a nameserver on the configured address in *Server.
 func (srv *Server) ListenAndServe() error {
 	srv.lock.Lock()
@@ -309,6 +367,7 @@ func (srv *Server) ListenAndServe() error {
 	if srv.started {
 		return &Error{err: "server already started"}
 	}
+
 	addr := srv.Addr
 	if addr == "" {
 		addr = ":domain"
@@ -316,6 +375,8 @@ func (srv *Server) ListenAndServe() error {
 	if srv.UDPSize == 0 {
 		srv.UDPSize = MinMsgSize
 	}
+	srv.queue = make(chan *response)
+	defer close(srv.queue)
 	switch srv.Net {
 	case "tcp", "tcp4", "tcp6":
 		a, err := net.ResolveTCPAddr(srv.Net, addr)
@@ -380,8 +441,11 @@ func (srv *Server) ActivateAndServe() error {
 	if srv.started {
 		return &Error{err: "server already started"}
 	}
+
 	pConn := srv.PacketConn
 	l := srv.Listener
+	srv.queue = make(chan *response)
+	defer close(srv.queue)
 	if pConn != nil {
 		if srv.UDPSize == 0 {
 			srv.UDPSize = MinMsgSize
@@ -439,7 +503,6 @@ func (srv *Server) getReadTimeout() time.Duration {
 }
 
 // serveTCP starts a TCP listener for the server.
-// Each request is handled in a separate goroutine.
 func (srv *Server) serveTCP(l net.Listener) error {
 	defer l.Close()
 
@@ -447,17 +510,6 @@ func (srv *Server) serveTCP(l net.Listener) error {
 		srv.NotifyStartedFunc()
 	}
 
-	reader := Reader(&defaultReader{srv})
-	if srv.DecorateReader != nil {
-		reader = srv.DecorateReader(reader)
-	}
-
-	handler := srv.Handler
-	if handler == nil {
-		handler = DefaultServeMux
-	}
-	rtimeout := srv.getReadTimeout()
-	// deadline is not used here
 	for {
 		rw, err := l.Accept()
 		srv.lock.RLock()
@@ -472,19 +524,11 @@ func (srv *Server) serveTCP(l net.Listener) error {
 			}
 			return err
 		}
-		go func() {
-			m, err := reader.ReadTCP(rw, rtimeout)
-			if err != nil {
-				rw.Close()
-				return
-			}
-			srv.serve(rw.RemoteAddr(), handler, m, nil, nil, rw)
-		}()
+		srv.spawnWorker(&response{tsigSecret: srv.TsigSecret, tcp: rw})
 	}
 }
 
 // serveUDP starts a UDP listener for the server.
-// Each request is handled in a separate goroutine.
 func (srv *Server) serveUDP(l *net.UDPConn) error {
 	defer l.Close()
 
@@ -497,10 +541,6 @@ func (srv *Server) serveUDP(l *net.UDPConn) error {
 		reader = srv.DecorateReader(reader)
 	}
 
-	handler := srv.Handler
-	if handler == nil {
-		handler = DefaultServeMux
-	}
 	rtimeout := srv.getReadTimeout()
 	// deadline is not used here
 	for {
@@ -520,80 +560,98 @@ func (srv *Server) serveUDP(l *net.UDPConn) error {
 		if len(m) < headerSize {
 			continue
 		}
-		go srv.serve(s.RemoteAddr(), handler, m, l, s, nil)
+		srv.spawnWorker(&response{msg: m, tsigSecret: srv.TsigSecret, udp: l, udpSession: s})
 	}
 }
 
-// Serve a new connection.
-func (srv *Server) serve(a net.Addr, h Handler, m []byte, u *net.UDPConn, s *SessionUDP, t net.Conn) {
-	w := &response{tsigSecret: srv.TsigSecret, udp: u, tcp: t, remoteAddr: a, udpSession: s}
+func (srv *Server) serve(w *response) {
 	if srv.DecorateWriter != nil {
 		w.writer = srv.DecorateWriter(w)
 	} else {
 		w.writer = w
 	}
 
-	q := 0 // counter for the amount of TCP queries we get
+	if w.udp != nil {
+		// serve UDP
+		srv.serveDNS(w)
+		return
+	}
 
 	reader := Reader(&defaultReader{srv})
 	if srv.DecorateReader != nil {
 		reader = srv.DecorateReader(reader)
 	}
-Redo:
+
+	defer func() {
+		if !w.hijacked {
+			w.Close()
+		}
+	}()
+
+	idleTimeout := tcpIdleTimeout
+	if srv.IdleTimeout != nil {
+		idleTimeout = srv.IdleTimeout()
+	}
+
+	timeout := srv.getReadTimeout()
+
+	limit := srv.MaxTCPQueries
+	if limit == 0 {
+		limit = maxTCPQueries
+	}
+
+	for q := 0; q < limit || limit == -1; q++ {
+		var err error
+		w.msg, err = reader.ReadTCP(w.tcp, timeout)
+		if err != nil {
+			// TODO(tmthrgd): handle error
+			break
+		}
+		srv.serveDNS(w)
+		if w.tcp == nil {
+			break // Close() was called
+		}
+		if w.hijacked {
+			break // client will call Close() themselves
+		}
+		// The first read uses the read timeout, the rest use the
+		// idle timeout.
+		timeout = idleTimeout
+	}
+}
+
+func (srv *Server) serveDNS(w *response) {
 	req := new(Msg)
-	err := req.Unpack(m)
+	err := req.Unpack(w.msg)
 	if err != nil { // Send a FormatError back
 		x := new(Msg)
 		x.SetRcodeFormatError(req)
 		w.WriteMsg(x)
-		goto Exit
+		return
 	}
 	if !srv.Unsafe && req.Response {
-		goto Exit
+		return
 	}
 
 	w.tsigStatus = nil
 	if w.tsigSecret != nil {
 		if t := req.IsTsig(); t != nil {
-			secret := t.Hdr.Name
-			if _, ok := w.tsigSecret[secret]; !ok {
-				w.tsigStatus = ErrKeyAlg
+			if secret, ok := w.tsigSecret[t.Hdr.Name]; ok {
+				w.tsigStatus = TsigVerify(w.msg, secret, "", false)
+			} else {
+				w.tsigStatus = ErrSecret
 			}
-			w.tsigStatus = TsigVerify(m, w.tsigSecret[secret], "", false)
 			w.tsigTimersOnly = false
 			w.tsigRequestMAC = req.Extra[len(req.Extra)-1].(*TSIG).MAC
 		}
 	}
-	h.ServeDNS(w, req) // Writes back to the client
 
-Exit:
-	if w.tcp == nil {
-		return
-	}
-	// TODO(miek): make this number configurable?
-	if q > maxTCPQueries { // close socket after this many queries
-		w.Close()
-		return
+	handler := srv.Handler
+	if handler == nil {
+		handler = DefaultServeMux
 	}
 
-	if w.hijacked {
-		return // client calls Close()
-	}
-	if u != nil { // UDP, "close" and return
-		w.Close()
-		return
-	}
-	idleTimeout := tcpIdleTimeout
-	if srv.IdleTimeout != nil {
-		idleTimeout = srv.IdleTimeout()
-	}
-	m, err = reader.ReadTCP(w.tcp, idleTimeout)
-	if err == nil {
-		q++
-		goto Redo
-	}
-	w.Close()
-	return
+	handler.ServeDNS(w, req) // Writes back to the client
 }
 
 func (srv *Server) readTCP(conn net.Conn, timeout time.Duration) ([]byte, error) {
@@ -696,7 +754,12 @@ func (w *response) LocalAddr() net.Addr {
 }
 
 // RemoteAddr implements the ResponseWriter.RemoteAddr method.
-func (w *response) RemoteAddr() net.Addr { return w.remoteAddr }
+func (w *response) RemoteAddr() net.Addr {
+	if w.tcp != nil {
+		return w.tcp.RemoteAddr()
+	}
+	return w.udpSession.RemoteAddr()
+}
 
 // TsigStatus implements the ResponseWriter.TsigStatus method.
 func (w *response) TsigStatus() error { return w.tsigStatus }