From e1cb18539ad5c9cd8542a2a9893a924217232c17 Mon Sep 17 00:00:00 2001
From: Miek Gieben <miek@miek.nl>
Date: Mon, 21 Jul 2014 15:24:55 +0100
Subject: [PATCH] Systemd support

Rename StartAndServe to ActivateAndServe and only use one PacketConn or
Listener. This just adds a new entry point into starting a server.
---
 server.go | 40 +++++++++++++++++++++-------------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/server.go b/server.go
index 3713f85f..9c8797c7 100644
--- a/server.go
+++ b/server.go
@@ -90,17 +90,19 @@ func HandleFailed(w ResponseWriter, r *Msg) {
 
 func failedHandler() Handler { return HandlerFunc(HandleFailed) }
 
-// Start a server on addresss and network speficied. Invoke handler
+// ListenAndServe Starts a server on addresss and network speficied. Invoke handler
 // for incoming queries.
 func ListenAndServe(addr string, network string, handler Handler) error {
 	server := &Server{Addr: addr, Net: network, Handler: handler}
 	return server.ListenAndServe()
 }
 
-// Start a server with these listeners. Invoke handler for incoming queries.
-func StartAndServe(ls []net.Listener, ps []net.PacketConn, handler Handler) error {
-	server := &Server{Listeners: ls, PacketConns: ps, Handler: handler}
-	return server.StartAndServe()
+// ActivateAndServe activates a server with a listener, l and p should not both be non-nil.
+// If both l and p are not nil only p will be used.
+// Invoke handler for incoming queries.
+func ActivateAndServe(l net.Listener, p net.PacketConn, handler Handler) error {
+	server := &Server{Listener: l, PacketConn: p, Handler: handler}
+	return server.ActivateAndServe()
 }
 
 func (mux *ServeMux) match(q string, t uint16) Handler {
@@ -203,10 +205,10 @@ type Server struct {
 	Addr string
 	// if "tcp" it will invoke a TCP listener, otherwise an UDP one.
 	Net string
-	// TCP Listeners to use, this is to aid in systemd's socket activation.
-	Listeners []net.Listener
-	// UDP "Listeners" to use, this is to aid in systemd's socket activation.
-	PacketConns []net.PacketConn
+	// TCP Listener to use, this is to aid in systemd's socket activation.
+	Listener net.Listener
+	// UDP "Listener" to use, this is to aid in systemd's socket activation.
+	PacketConn net.PacketConn
 	// Handler to invoke, dns.DefaultServeMux if nil.
 	Handler Handler
 	// Default buffer size to use to read incoming UDP messages. If not set
@@ -262,25 +264,25 @@ func (srv *Server) ListenAndServe() error {
 	return &Error{err: "bad network"}
 }
 
-// StartAndServe starts a nameserver with the first listener the or first
-// packetconn configured in *Server.
-func (srv *Server) StartAndServe() error {
-	if len(srv.Listeners) > 0 {
-		if t, ok := srv.Listeners[0].(*net.TCPListener); ok {
-			return srv.serveTCP(t)
-		}
-	}
-	if len(srv.PacketConns) > 0 {
+// ActivateAndServe starts a nameserver with the PacketConn or Listener
+// configured in *Server.
+func (srv *Server) ActivateAndServe() error {
+	if srv.PacketConn != nil {
 		if srv.UDPSize == 0 {
 			srv.UDPSize = MinMsgSize
 		}
-		if t, ok := srv.PacketConns[0].(*net.UDPConn); ok {
+		if t, ok := srv.PacketConn.(*net.UDPConn); ok {
 			if e := setUDPSocketOptions(t); e != nil {
 				return e
 			}
 			return srv.serveUDP(t)
 		}
 	}
+	if srv.Listener != nil {
+		if t, ok := srv.Listener.(*net.TCPListener); ok {
+			return srv.serveTCP(t)
+		}
+	}
 	return &Error{err: "bad listeners"}
 }