Make CoreDNS a server type plugin for Caddy (#220)

* Make CoreDNS a server type plugin for Caddy

Remove code we don't need and port all middleware over. Fix all tests
and rework the documentation.

Also make `go generate` build a caddy binary which we then copy into
our directory. This means `go build`-builds remain working as-is.

And new etc instances in each etcd test for better isolation.
Fix more tests and rework test.Server with the newer support Caddy offers.

Fix Makefile to support new mode of operation.

1 files changed, 15 insertions, 32 deletions

diff --git a/server/server.go b/server/server.go
index 0ba6f7f01..b0f89468e 100644
--- a/server/server.go
+++ b/server/server.go
@@ -28,13 +28,10 @@ import (
 // the same address and the listener may be stopped for
 // graceful termination (POSIX only).
 type Server struct {
-	Addr   string // Address we listen on
-	mux    *dns.ServeMux
-	server [2]*dns.Server // by convention 0 is tcp and 1 is udp
-
-	tcp        net.Listener
-	udp        net.PacketConn
-	listenerMu sync.Mutex // protects listener and packetconn
+	Addr       string // Address we listen on
+	mux        *dns.ServeMux
+	server     [2]*dns.Server // by convention 0 is tcp and 1 is udp
+	listenerMu sync.Mutex     // protects listener and packetconn inside server
 
 	tls         bool // whether this server is serving all HTTPS hosts or not
 	TLSConfig   *tls.Config
@@ -115,16 +112,6 @@ func New(addr string, configs []Config, gracefulTimeout time.Duration) (*Server,
 	return s, nil
 }
 
-// LocalAddr return the addresses where the server is bound to. The TCP listener
-// address is the first returned, the UDP conn address the second.
-func (s *Server) LocalAddr() (net.Addr, net.Addr) {
-	s.listenerMu.Lock()
-	tcp := s.tcp.Addr()
-	udp := s.udp.LocalAddr()
-	s.listenerMu.Unlock()
-	return tcp, udp
-}
-
 // Serve starts the server with an existing listener. It blocks until the server stops.
 func (s *Server) Serve(ln net.Listener, pc net.PacketConn) error {
 	err := s.setup()
@@ -134,9 +121,7 @@ func (s *Server) Serve(ln net.Listener, pc net.PacketConn) error {
 	}
 	s.listenerMu.Lock()
 	s.server[0] = &dns.Server{Listener: ln, Net: "tcp", Handler: s.mux}
-	s.tcp = ln
 	s.server[1] = &dns.Server{PacketConn: pc, Net: "udp", Handler: s.mux}
-	s.udp = pc
 	s.listenerMu.Unlock()
 
 	go func() {
@@ -168,9 +153,7 @@ func (s *Server) ListenAndServe() error {
 
 	s.listenerMu.Lock()
 	s.server[0] = &dns.Server{Listener: l, Net: "tcp", Handler: s.mux}
-	s.tcp = l
 	s.server[1] = &dns.Server{PacketConn: pc, Net: "udp", Handler: s.mux}
-	s.udp = pc
 	s.listenerMu.Unlock()
 
 	go func() {
@@ -252,17 +235,17 @@ func (s *Server) Stop() (err error) {
 
 	// Close the listener now; this stops the server without delay
 	s.listenerMu.Lock()
-	if s.tcp != nil {
-		err = s.tcp.Close()
-	}
-	if s.udp != nil {
-		err = s.udp.Close()
-	}
+	defer s.listenerMu.Unlock()
 
 	for _, s1 := range s.server {
+		if s1.Listener != nil {
+			err = s1.Listener.Close()
+		}
+		if s1.PacketConn != nil {
+			err = s1.PacketConn.Close()
+		}
 		err = s1.Shutdown()
 	}
-	s.listenerMu.Unlock()
 
 	return
 }
@@ -280,8 +263,8 @@ func (s *Server) WaitUntilStarted() {
 func (s *Server) ListenerFd() *os.File {
 	s.listenerMu.Lock()
 	defer s.listenerMu.Unlock()
-	if s.tcp != nil {
-		file, _ := s.tcp.(*net.TCPListener).File()
+	if s.server[0].Listener != nil {
+		file, _ := s.server[0].Listener.(*net.TCPListener).File()
 		return file
 	}
 	return nil
@@ -293,8 +276,8 @@ func (s *Server) ListenerFd() *os.File {
 func (s *Server) PacketConnFd() *os.File {
 	s.listenerMu.Lock()
 	defer s.listenerMu.Unlock()
-	if s.udp != nil {
-		file, _ := s.udp.(*net.UDPConn).File()
+	if s.server[1].PacketConn != nil {
+		file, _ := s.server[1].PacketConn.(*net.UDPConn).File()
 		return file
 	}
 	return nil