Merge branch 'pr394': Add localDomain option to weavedns

Improve the DNS server configuration mechanism. The new configuration
system includes the ability to specify a different domain name other
than ".weave.local".

nameserver/mdns_server.go

@@ -35,7 +35,7 @@ func (s *MDNSServer) addrIsLocal(testaddr net.Addr) bool {
 	return false
 }
 
-func (s *MDNSServer) Start(ifi *net.Interface) error {
+func (s *MDNSServer) Start(ifi *net.Interface, localDomain string) error {
 	conn, err := LinkLocalMulticastListener(ifi)
 	if err != nil {
 		return err
@@ -69,7 +69,7 @@ func (s *MDNSServer) Start(ifi *net.Interface) error {
 		})
 
 	mux := dns.NewServeMux()
-	mux.HandleFunc(LOCAL_DOMAIN, handleLocal)
+	mux.HandleFunc(localDomain, handleLocal)
 	mux.HandleFunc(RDNS_DOMAIN, handleReverse)
 
 	go dns.ActivateAndServe(nil, conn, mux)

nameserver/mdns_server_test.go

@@ -44,7 +44,7 @@ func TestServerSimpleQuery(t *testing.T) {
 
 	mdnsServer, err := NewMDNSServer(zone)
 	wt.AssertNoErr(t, err)
-	err = mdnsServer.Start(nil)
+	err = mdnsServer.Start(nil, DEFAULT_LOCAL_DOMAIN)
 	wt.AssertNoErr(t, err)
 
 	var receivedAddr net.IP

nameserver/server.go

@@ -9,8 +9,11 @@ import (
 )
 
 const (
-	LOCAL_DOMAIN = "weave.local."
-	UDPBufSize   = 4096 // bigger than the default 512
+	DEFAULT_LOCAL_DOMAIN = "weave.local."     // The default name used for the local domain
+	DEFAULT_SERVER_PORT  = 53                 // The default server port
+	DEFAULT_CLI_CFG_FILE = "/etc/resolv.conf" // default "resolv.conf" file to try to load
+	DEFAULT_UDP_BUFLEN   = 4096               // bigger than the default 512
+	DEFAULT_IFACE_NAME   = "default interface"
 )
 
 func makeDNSFailResponse(r *dns.Msg) *dns.Msg {
@@ -21,59 +24,95 @@ func makeDNSFailResponse(r *dns.Msg) *dns.Msg {
 	return m
 }
 
-type DNSServer struct {
-	config *dns.ClientConfig
-	zone   Zone
-	iface  *net.Interface
-	port   int
-	udpSrv *dns.Server
-	tcpSrv *dns.Server
+type DNSServerConfig struct {
+	// (Optional) client config file for resolving upstream servers
+	UpstreamCfgFile string
+	// (Optional) DNS client config for the fallback server(s)
+	UpstreamCfg *dns.ClientConfig
+	// (Optional) port number (for TCP and UDP)
+	Port int
+	// (Optional) local domain (ie, "weave.local.")
+	LocalDomain string
 }
 
-// Creates a new DNS server with a given config
-func NewDNSServer(config *dns.ClientConfig, zone Zone, iface *net.Interface, port int) *DNSServer {
-	return &DNSServer{
-		config: config,
+type DNSServer struct {
+	udpSrv   *dns.Server
+	tcpSrv   *dns.Server
+	mdnsCli  *MDNSClient
+	mdnsSrv  *MDNSServer
+	zone     Zone
+	iface    *net.Interface
+	upstream *dns.ClientConfig
+
+	Domain     string // the local domain
+	IfaceName  string // the interface where mDNS is working on
+	ListenAddr string // the address the server is listening at
+}
+
+// Creates a new DNS server
+func NewDNSServer(config DNSServerConfig, zone Zone, iface *net.Interface) (s *DNSServer, err error) {
+	s = &DNSServer{
 		zone:   zone,
 		iface:  iface,
-		port:   port,
+
+		Domain:     DEFAULT_LOCAL_DOMAIN,
+		IfaceName:  DEFAULT_IFACE_NAME,
+		ListenAddr: fmt.Sprintf(":%d", DEFAULT_SERVER_PORT),
 	}
-}
 
-// Start the DNS server
-func (s *DNSServer) Start() error {
-	Info.Printf("WeaveDNS server starting...")
-
-	mdnsClient, err := NewMDNSClient()
-	CheckFatal(err)
-
-	ifaceName := "default interface"
-	if s.iface != nil {
-		ifaceName = s.iface.Name
+	// fill empty parameters with defaults...
+	if config.Port != 0 {
+		s.ListenAddr = fmt.Sprintf(":%d", config.Port)
+	}
+	if len(config.LocalDomain) > 0 {
+		s.Domain = config.LocalDomain
+	}
+	if config.UpstreamCfg != nil {
+		s.upstream = config.UpstreamCfg
+	} else {
+		cfgFile := DEFAULT_CLI_CFG_FILE
+		if len(config.UpstreamCfgFile) > 0 {
+			cfgFile = config.UpstreamCfgFile
+		}
+		if s.upstream, err = dns.ClientConfigFromFile(cfgFile); err != nil {
+			return nil, err
+		}
+	}
+	s.mdnsCli, err = NewMDNSClient()
+	if err != nil {
+		return
+	}
+	s.mdnsSrv, err = NewMDNSServer(s.zone)
+	if err != nil {
+		return
+	}
+	if iface != nil {
+		s.IfaceName = iface.Name
 	}
-	Info.Printf("Using mDNS on %s", ifaceName)
-	err = mdnsClient.Start(s.iface)
-	CheckFatal(err)
 
 	// create two DNS request multiplexerers, depending on the protocol used by clients
 	// (we use the same protocol for asking upstream servers)
 	mux := func(client *dns.Client) *dns.ServeMux {
 		m := dns.NewServeMux()
-		m.HandleFunc(LOCAL_DOMAIN, s.queryHandler([]Lookup{s.zone, mdnsClient}))
-		m.HandleFunc(RDNS_DOMAIN, s.rdnsHandler([]Lookup{s.zone, mdnsClient}, client))
+		m.HandleFunc(s.Domain, s.queryHandler([]Lookup{s.zone, s.mdnsCli}))
+		m.HandleFunc(RDNS_DOMAIN, s.rdnsHandler([]Lookup{s.zone, s.mdnsCli}, client))
 		m.HandleFunc(".", s.notUsHandler(client))
 		return m
 	}
 
-	mdnsServer, err := NewMDNSServer(s.zone)
-	CheckFatal(err)
+	s.udpSrv = &dns.Server{Addr: s.ListenAddr, Net: "udp", Handler: mux(&dns.Client{Net: "udp", UDPSize: DEFAULT_UDP_BUFLEN})}
+	s.tcpSrv = &dns.Server{Addr: s.ListenAddr, Net: "tcp", Handler: mux(&dns.Client{Net: "tcp"})}
 
-	err = mdnsServer.Start(s.iface)
-	CheckFatal(err)
+	return
+}
 
-	address := fmt.Sprintf(":%d", s.port)
-	s.udpSrv = &dns.Server{Addr: address, Net: "udp", Handler: mux(&dns.Client{Net: "udp", UDPSize: UDPBufSize})}
-	s.tcpSrv = &dns.Server{Addr: address, Net: "tcp", Handler: mux(&dns.Client{Net: "tcp"})}
+// Start the DNS server
+func (s *DNSServer) Start() error {
+	Info.Printf("Using mDNS on %s", s.IfaceName)
+	err := s.mdnsCli.Start(s.iface)
+	CheckFatal(err)
+	err = s.mdnsSrv.Start(s.iface, s.Domain)
+	CheckFatal(err)
 
 	wg := new(sync.WaitGroup)
 	wg.Add(2)
@@ -81,7 +120,7 @@ func (s *DNSServer) Start() error {
 	go func() {
 		defer wg.Done()
 
-		Debug.Printf("Listening for DNS on %s (UDP)", address)
+		Debug.Printf("Listening for DNS on %s (UDP)", s.ListenAddr)
 		err = s.udpSrv.ListenAndServe()
 		CheckFatal(err)
 		Debug.Printf("DNS UDP server exiting...")
@@ -90,7 +129,7 @@ func (s *DNSServer) Start() error {
 	go func() {
 		defer wg.Done()
 
-		Debug.Printf("Listening for DNS on %s (TCP)", address)
+		Debug.Printf("Listening for DNS on %s (TCP)", s.ListenAddr)
 		err = s.tcpSrv.ListenAndServe()
 		CheckFatal(err)
 		Debug.Printf("DNS TCP server exiting...")
@@ -111,6 +150,7 @@ func (s *DNSServer) Stop() error {
 	if err := s.udpSrv.Shutdown(); err != nil {
 		return err
 	}
+	// TODO: shutdown the mDNS client/server
 	return nil
 }
 
@@ -160,8 +200,8 @@ func (s *DNSServer) notUsHandler(dnsClient *dns.Client) dns.HandlerFunc {
 	return func(w dns.ResponseWriter, r *dns.Msg) {
 		q := r.Question[0]
 		Debug.Printf("[dns msgid %d] Fallback query: %+v", r.MsgHdr.Id, q)
-		for _, server := range s.config.Servers {
-			reply, _, err := dnsClient.Exchange(r, fmt.Sprintf("%s:%s", server, s.config.Port))
+		for _, server := range s.upstream.Servers {
+			reply, _, err := dnsClient.Exchange(r, fmt.Sprintf("%s:%s", server, s.upstream.Port))
 			if err != nil {
 				Debug.Printf("[dns msgid %d] Network error trying %s (%s)",
 					r.MsgHdr.Id, server, err)

nameserver/server_test.go

@@ -25,7 +25,7 @@ func TestUDPDNSServer(t *testing.T) {
 		nonLocalName    = "weave.works."
 		testAddr1       = "10.0.2.1"
 	)
-	dnsAddr := fmt.Sprintf("localhost:%d", port)
+	dnsAddr := fmt.Sprintf("127.0.0.1:%d", port)
 	testCIDR1 := testAddr1 + "/24"
 
 	InitDefaultLogging(true)
@@ -66,13 +66,14 @@ func TestUDPDNSServer(t *testing.T) {
 	wt.AssertNoErr(t, err)
 
 	config := &dns.ClientConfig{Servers: []string{"127.0.0.1"}, Port: fallbackPort}
-	srv := NewDNSServer(config, zone, nil, port)
+	srv, err := NewDNSServer(DNSServerConfig{UpstreamCfg: config, Port: port}, zone, nil)
+	wt.AssertNoErr(t, err)
 	defer srv.Stop()
 	go srv.Start()
 	time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
 
 	c := new(dns.Client)
-	c.UDPSize = UDPBufSize
+	c.UDPSize = DEFAULT_UDP_BUFLEN
 	m := new(dns.Msg)
 	m.SetQuestion(successTestName, dns.TypeA)
 	m.RecursionDesired = true
@@ -189,14 +190,15 @@ func TestTCPDNSServer(t *testing.T) {
 
 	t.Logf("Creating a WeaveDNS server instance, falling back to 127.0.0.1:%s", fallbackPort)
 	config := &dns.ClientConfig{Servers: []string{"127.0.0.1"}, Port: fallbackPort}
-	srv := NewDNSServer(config, zone, nil, port)
+	srv, err := NewDNSServer(DNSServerConfig{UpstreamCfg: config, Port: port}, zone, nil)
+	wt.AssertNoErr(t, err)
 	defer srv.Stop()
 	go srv.Start()
 	time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
 
 	t.Logf("Creating a UDP and a TCP client")
 	uc := new(dns.Client)
-	uc.UDPSize = UDPBufSize
+	uc.UDPSize = DEFAULT_UDP_BUFLEN
 	tc := new(dns.Client)
 	tc.Net = "tcp"
 

test/220_dns_custom_test.sh

@@ -0,0 +1,25 @@
+#! /bin/bash
+
+. ./config.sh
+
+C1=10.2.56.34
+C2=10.2.54.91
+
+start_suite "Resolve names in custom domain"
+
+run_on $HOST1 sudo $WEAVE stop || true
+run_on $HOST1 sudo $WEAVE stop-dns || true
+run_on $HOST1 sudo $WEAVE launch-dns 10.0.0.2/8 --localDomain foo.bar.
+
+docker_on $HOST1 rm -f c1 c2 || true
+
+run_on $HOST1 sudo $WEAVE run $C2/24 -t --name=c2 -h seetwo.foo.bar ubuntu
+run_on $HOST1 sudo $WEAVE run --with-dns $C1/24 -t --name=c1 aanand/docker-dnsutils /bin/sh
+
+ok=$(docker -H tcp://$HOST1:2375 exec -i c1 sh -c "dig +short seetwo.foo.bar.")
+assert "echo $ok" "$C2"
+
+ok=$(docker -H tcp://$HOST1:2375 exec -i c1 sh -c "dig +short -x $C2")
+assert "echo $ok" "seetwo.foo.bar."
+
+end_suite

weavedns/main.go

@@ -19,6 +19,7 @@ func main() {
 		justVersion bool
 		ifaceName   string
 		apiPath     string
+		localDomain string
 		fallback    string
 		dnsPort     int
 		httpPort    int
@@ -31,10 +32,11 @@ func main() {
 	flag.BoolVar(&justVersion, "version", false, "print version and exit")
 	flag.StringVar(&ifaceName, "iface", "", "name of interface to use for multicast")
 	flag.StringVar(&apiPath, "api", "unix:///var/run/docker.sock", "Path to Docker API socket")
+	flag.StringVar(&localDomain, "localDomain", "", "local domain (ie, 'weave.local.')")
 	flag.IntVar(&wait, "wait", 0, "number of seconds to wait for interface to be created and come up")
 	flag.IntVar(&dnsPort, "dnsport", 53, "port to listen to DNS requests")
 	flag.IntVar(&httpPort, "httpport", 6785, "port to listen to HTTP requests")
-	flag.StringVar(&fallback, "fallback", "", "Fallback server and port (ie, '8.8.8.8:53')")
+	flag.StringVar(&fallback, "fallback", "", "fallback server and port (ie, '8.8.8.8:53')")
 	flag.BoolVar(&watch, "watch", true, "watch the docker socket for container events")
 	flag.BoolVar(&debug, "debug", false, "output debugging info to stderr")
 	flag.Parse()
@@ -67,25 +69,27 @@ func main() {
 		}
 	}
 
-	var config *dns.ClientConfig
+	srvConfig := weavedns.DNSServerConfig{
+		Port:        dnsPort,
+		LocalDomain: localDomain,
+	}
+	
 	if len(fallback) > 0 {
 		fallbackHost, fallbackPort, err := net.SplitHostPort(fallback)
 		if err != nil {
 			Error.Fatal("Fould not parse fallback host and port", err)
 		}
-		config = &dns.ClientConfig{Servers: []string{fallbackHost}, Port: fallbackPort}
+		srvConfig.UpstreamCfg = &dns.ClientConfig{Servers: []string{fallbackHost}, Port: fallbackPort}
 		Debug.Printf("DNS fallback at %s:%s", fallbackHost, fallbackPort)
-	} else {
-		config, err = dns.ClientConfigFromFile("/etc/resolv.conf")
-		if err != nil {
-			Error.Fatal("Failed obtain DNS client configuration", err)
-		}
 	}
-
-	go weavedns.ListenHttp(weavedns.LOCAL_DOMAIN, zone, httpPort)
-	srv := weavedns.NewDNSServer(config, zone, iface, dnsPort)
+		
+	go weavedns.ListenHttp(localDomain, zone, httpPort)
+	srv, err := weavedns.NewDNSServer(srvConfig, zone, iface)
+	if err != nil {
+		Error.Fatal("Failed to initialize the WeaveDNS server", err)
+	}
 	err = srv.Start()
 	if err != nil {
-		Error.Fatal("Failed to start server", err)
+		Error.Fatal("Failed to start the WeaveDNS server", err)
 	}
 }