Updating dependencies.

vendor/github.com/miekg/dns/server.go

@@ -41,6 +41,17 @@ type Handler interface {
 	ServeDNS(w ResponseWriter, r *Msg)
 }
 
+// The HandlerFunc type is an adapter to allow the use of
+// ordinary functions as DNS handlers.  If f is a function
+// with the appropriate signature, HandlerFunc(f) is a
+// Handler object that calls f.
+type HandlerFunc func(ResponseWriter, *Msg)
+
+// ServeDNS calls f(w, r).
+func (f HandlerFunc) ServeDNS(w ResponseWriter, r *Msg) {
+	f(w, r)
+}
+
 // A ResponseWriter interface is used by an DNS handler to
 // construct an DNS response.
 type ResponseWriter interface {
@@ -71,9 +82,10 @@ type ConnectionStater interface {
 
 type response struct {
 	msg            []byte
+	closed         bool // connection has been closed
 	hijacked       bool // connection has been hijacked by handler
-	tsigStatus     error
 	tsigTimersOnly bool
+	tsigStatus     error
 	tsigRequestMAC string
 	tsigSecret     map[string]string // the tsig secrets
 	udp            *net.UDPConn      // i/o connection if UDP was used
@@ -83,35 +95,6 @@ type response struct {
 	wg             *sync.WaitGroup   // for gracefull shutdown
 }
 
-// ServeMux is an DNS request multiplexer. It matches the
-// zone name of each incoming request against a list of
-// registered patterns add calls the handler for the pattern
-// that most closely matches the zone name. ServeMux is DNSSEC aware, meaning
-// that queries for the DS record are redirected to the parent zone (if that
-// is also registered), otherwise the child gets the query.
-// ServeMux is also safe for concurrent access from multiple goroutines.
-type ServeMux struct {
-	z map[string]Handler
-	m *sync.RWMutex
-}
-
-// NewServeMux allocates and returns a new ServeMux.
-func NewServeMux() *ServeMux { return &ServeMux{z: make(map[string]Handler), m: new(sync.RWMutex)} }
-
-// DefaultServeMux is the default ServeMux used by Serve.
-var DefaultServeMux = NewServeMux()
-
-// The HandlerFunc type is an adapter to allow the use of
-// ordinary functions as DNS handlers.  If f is a function
-// with the appropriate signature, HandlerFunc(f) is a
-// Handler object that calls f.
-type HandlerFunc func(ResponseWriter, *Msg)
-
-// ServeDNS calls f(w, r).
-func (f HandlerFunc) ServeDNS(w ResponseWriter, r *Msg) {
-	f(w, r)
-}
-
 // HandleFailed returns a HandlerFunc that returns SERVFAIL for every request it gets.
 func HandleFailed(w ResponseWriter, r *Msg) {
 	m := new(Msg)
@@ -120,8 +103,6 @@ func HandleFailed(w ResponseWriter, r *Msg) {
 	w.WriteMsg(m)
 }
 
-func failedHandler() Handler { return HandlerFunc(HandleFailed) }
-
 // ListenAndServe Starts a server on address and network specified Invoke handler
 // for incoming queries.
 func ListenAndServe(addr string, network string, handler Handler) error {
@@ -160,99 +141,6 @@ func ActivateAndServe(l net.Listener, p net.PacketConn, handler Handler) error {
 	return server.ActivateAndServe()
 }
 
-func (mux *ServeMux) match(q string, t uint16) Handler {
-	mux.m.RLock()
-	defer mux.m.RUnlock()
-	var handler Handler
-	b := make([]byte, len(q)) // worst case, one label of length q
-	off := 0
-	end := false
-	for {
-		l := len(q[off:])
-		for i := 0; i < l; i++ {
-			b[i] = q[off+i]
-			if b[i] >= 'A' && b[i] <= 'Z' {
-				b[i] |= 'a' - 'A'
-			}
-		}
-		if h, ok := mux.z[string(b[:l])]; ok { // causes garbage, might want to change the map key
-			if t != TypeDS {
-				return h
-			}
-			// Continue for DS to see if we have a parent too, if so delegeate to the parent
-			handler = h
-		}
-		off, end = NextLabel(q, off)
-		if end {
-			break
-		}
-	}
-	// Wildcard match, if we have found nothing try the root zone as a last resort.
-	if h, ok := mux.z["."]; ok {
-		return h
-	}
-	return handler
-}
-
-// Handle adds a handler to the ServeMux for pattern.
-func (mux *ServeMux) Handle(pattern string, handler Handler) {
-	if pattern == "" {
-		panic("dns: invalid pattern " + pattern)
-	}
-	mux.m.Lock()
-	mux.z[Fqdn(pattern)] = handler
-	mux.m.Unlock()
-}
-
-// HandleFunc adds a handler function to the ServeMux for pattern.
-func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Msg)) {
-	mux.Handle(pattern, HandlerFunc(handler))
-}
-
-// HandleRemove deregistrars the handler specific for pattern from the ServeMux.
-func (mux *ServeMux) HandleRemove(pattern string) {
-	if pattern == "" {
-		panic("dns: invalid pattern " + pattern)
-	}
-	mux.m.Lock()
-	delete(mux.z, Fqdn(pattern))
-	mux.m.Unlock()
-}
-
-// ServeDNS dispatches the request to the handler whose
-// pattern most closely matches the request message. If DefaultServeMux
-// is used the correct thing for DS queries is done: a possible parent
-// is sought.
-// If no handler is found a standard SERVFAIL message is returned
-// If the request message does not have exactly one question in the
-// question section a SERVFAIL is returned, unlesss Unsafe is true.
-func (mux *ServeMux) ServeDNS(w ResponseWriter, request *Msg) {
-	var h Handler
-	if len(request.Question) < 1 { // allow more than one question
-		h = failedHandler()
-	} else {
-		if h = mux.match(request.Question[0].Name, request.Question[0].Qtype); h == nil {
-			h = failedHandler()
-		}
-	}
-	h.ServeDNS(w, request)
-}
-
-// Handle registers the handler with the given pattern
-// in the DefaultServeMux. The documentation for
-// ServeMux explains how patterns are matched.
-func Handle(pattern string, handler Handler) { DefaultServeMux.Handle(pattern, handler) }
-
-// HandleRemove deregisters the handle with the given pattern
-// in the DefaultServeMux.
-func HandleRemove(pattern string) { DefaultServeMux.HandleRemove(pattern) }
-
-// HandleFunc registers the handler function with the given pattern
-// in the DefaultServeMux.
-func HandleFunc(pattern string, handler func(ResponseWriter, *Msg)) {
-	DefaultServeMux.HandleFunc(pattern, handler)
-}
-
 // Writer writes raw DNS messages; each call to Write should send an entire message.
 type Writer interface {
 	io.Writer
@@ -315,9 +203,6 @@ type Server struct {
 	IdleTimeout func() time.Duration
 	// Secret(s) for Tsig map[<zonename>]<base64 secret>. The zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2).
 	TsigSecret map[string]string
-	// Unsafe instructs the server to disregard any sanity checks and directly hand the message to
-	// the handler. It will specifically not check if the query has the QR bit not set.
-	Unsafe bool
 	// If NotifyStartedFunc is set it is called once the server has started listening.
 	NotifyStartedFunc func()
 	// DecorateReader is optional, allows customization of the process that reads raw DNS messages.
@@ -329,6 +214,9 @@ type Server struct {
 	// Whether to set the SO_REUSEPORT socket option, allowing multiple listeners to be bound to a single address.
 	// It is only supported on go1.11+ and when using ListenAndServe.
 	ReusePort bool
+	// AcceptMsgFunc will check the incoming message and will reject it early in the process.
+	// By default DefaultMsgAcceptFunc will be used.
+	MsgAcceptFunc MsgAcceptFunc
 
 	// UDP packet or TCP connection queue
 	queue chan *response
@@ -412,6 +300,9 @@ func (srv *Server) init() {
 	if srv.UDPSize == 0 {
 		srv.UDPSize = MinMsgSize
 	}
+	if srv.MsgAcceptFunc == nil {
+		srv.MsgAcceptFunc = defaultMsgAcceptFunc
+	}
 
 	srv.udpPool.New = makeUDPBuffer(srv.UDPSize)
 }
@@ -529,14 +420,13 @@ func (srv *Server) Shutdown() error {
 // to terminate.
 func (srv *Server) ShutdownContext(ctx context.Context) error {
 	srv.lock.Lock()
-	started := srv.started
-	srv.started = false
-	srv.lock.Unlock()
-
-	if !started {
+	if !srv.started {
+		srv.lock.Unlock()
 		return &Error{err: "server not started"}
 	}
 
+	srv.started = false
+
 	if srv.PacketConn != nil {
 		srv.PacketConn.SetReadDeadline(aLongTimeAgo) // Unblock reads
 	}
@@ -545,10 +435,10 @@ func (srv *Server) ShutdownContext(ctx context.Context) error {
 		srv.Listener.Close()
 	}
 
-	srv.lock.Lock()
 	for rw := range srv.conns {
 		rw.SetReadDeadline(aLongTimeAgo) // Unblock reads
 	}
+
 	srv.lock.Unlock()
 
 	if testShutdownNotify != nil {
@@ -735,20 +625,43 @@ func (srv *Server) serve(w *response) {
 	}
 }
 
-func (srv *Server) serveDNS(w *response) {
-	req := new(Msg)
-	err := req.Unpack(w.msg)
+func (srv *Server) disposeBuffer(w *response) {
 	if w.udp != nil && cap(w.msg) == srv.UDPSize {
 		srv.udpPool.Put(w.msg[:srv.UDPSize])
 	}
 	w.msg = nil
-	if err != nil { // Send a FormatError back
-		x := new(Msg)
-		x.SetRcodeFormatError(req)
-		w.WriteMsg(x)
+}
+
+func (srv *Server) serveDNS(w *response) {
+	dh, off, err := unpackMsgHdr(w.msg, 0)
+	if err != nil {
+		// Let client hang, they are sending crap; any reply can be used to amplify.
 		return
 	}
-	if !srv.Unsafe && req.Response {
+
+	req := new(Msg)
+	req.setHdr(dh)
+
+	switch srv.MsgAcceptFunc(dh) {
+	case MsgAccept:
+	case MsgIgnore:
+		return
+	case MsgReject:
+		req.SetRcodeFormatError(req)
+		// Are we allowed to delete any OPT records here?
+		req.Ns, req.Answer, req.Extra = nil, nil, nil
+
+		w.WriteMsg(req)
+		srv.disposeBuffer(w)
+		return
+	}
+
+	if err := req.unpack(dh, w.msg, off); err != nil {
+		req.SetRcodeFormatError(req)
+		req.Ns, req.Answer, req.Extra = nil, nil, nil
+
+		w.WriteMsg(req)
+		srv.disposeBuffer(w)
 		return
 	}
 
@@ -765,6 +678,8 @@ func (srv *Server) serveDNS(w *response) {
 		}
 	}
 
+	srv.disposeBuffer(w)
+
 	handler := srv.Handler
 	if handler == nil {
 		handler = DefaultServeMux
@@ -774,7 +689,16 @@ func (srv *Server) serveDNS(w *response) {
 }
 
 func (srv *Server) readTCP(conn net.Conn, timeout time.Duration) ([]byte, error) {
-	conn.SetReadDeadline(time.Now().Add(timeout))
+	// If we race with ShutdownContext, the read deadline may
+	// have been set in the distant past to unblock the read
+	// below. We must not override it, otherwise we may block
+	// ShutdownContext.
+	srv.lock.RLock()
+	if srv.started {
+		conn.SetReadDeadline(time.Now().Add(timeout))
+	}
+	srv.lock.RUnlock()
+
 	l := make([]byte, 2)
 	n, err := conn.Read(l)
 	if err != nil || n != 2 {
@@ -809,7 +733,13 @@ func (srv *Server) readTCP(conn net.Conn, timeout time.Duration) ([]byte, error)
 }
 
 func (srv *Server) readUDP(conn *net.UDPConn, timeout time.Duration) ([]byte, *SessionUDP, error) {
-	conn.SetReadDeadline(time.Now().Add(timeout))
+	srv.lock.RLock()
+	if srv.started {
+		// See the comment in readTCP above.
+		conn.SetReadDeadline(time.Now().Add(timeout))
+	}
+	srv.lock.RUnlock()
+
 	m := srv.udpPool.Get().([]byte)
 	n, s, err := ReadFromSessionUDP(conn, m)
 	if err != nil {
@@ -822,6 +752,10 @@ func (srv *Server) readUDP(conn *net.UDPConn, timeout time.Duration) ([]byte, *S
 
 // WriteMsg implements the ResponseWriter.WriteMsg method.
 func (w *response) WriteMsg(m *Msg) (err error) {
+	if w.closed {
+		return &Error{err: "WriteMsg called after Close"}
+	}
+
 	var data []byte
 	if w.tsigSecret != nil { // if no secrets, dont check for the tsig (which is a longer check)
 		if t := m.IsTsig(); t != nil {
@@ -843,6 +777,10 @@ func (w *response) WriteMsg(m *Msg) (err error) {
 
 // Write implements the ResponseWriter.Write method.
 func (w *response) Write(m []byte) (int, error) {
+	if w.closed {
+		return 0, &Error{err: "Write called after Close"}
+	}
+
 	switch {
 	case w.udp != nil:
 		n, err := WriteToSessionUDP(w.udp, m, w.udpSession)
@@ -861,24 +799,33 @@ func (w *response) Write(m []byte) (int, error) {
 
 		n, err := io.Copy(w.tcp, bytes.NewReader(m))
 		return int(n), err
+	default:
+		panic("dns: internal error: udp and tcp both nil")
 	}
-	panic("not reached")
 }
 
 // LocalAddr implements the ResponseWriter.LocalAddr method.
 func (w *response) LocalAddr() net.Addr {
-	if w.tcp != nil {
+	switch {
+	case w.udp != nil:
+		return w.udp.LocalAddr()
+	case w.tcp != nil:
 		return w.tcp.LocalAddr()
+	default:
+		panic("dns: internal error: udp and tcp both nil")
 	}
-	return w.udp.LocalAddr()
 }
 
 // RemoteAddr implements the ResponseWriter.RemoteAddr method.
 func (w *response) RemoteAddr() net.Addr {
-	if w.tcp != nil {
+	switch {
+	case w.udpSession != nil:
+		return w.udpSession.RemoteAddr()
+	case w.tcp != nil:
 		return w.tcp.RemoteAddr()
+	default:
+		panic("dns: internal error: udpSession and tcp both nil")
 	}
-	return w.udpSession.RemoteAddr()
 }
 
 // TsigStatus implements the ResponseWriter.TsigStatus method.
@@ -892,13 +839,20 @@ func (w *response) Hijack() { w.hijacked = true }
 
 // Close implements the ResponseWriter.Close method
 func (w *response) Close() error {
-	// Can't close the udp conn, as that is actually the listener.
-	if w.tcp != nil {
-		e := w.tcp.Close()
-		w.tcp = nil
-		return e
+	if w.closed {
+		return &Error{err: "connection already closed"}
+	}
+	w.closed = true
+
+	switch {
+	case w.udp != nil:
+		// Can't close the udp conn, as that is actually the listener.
+		return nil
+	case w.tcp != nil:
+		return w.tcp.Close()
+	default:
+		panic("dns: internal error: udp and tcp both nil")
 	}
-	return nil
 }
 
 // ConnectionState() implements the ConnectionStater.ConnectionState() interface.