Add TTL server option (#23)

This deprecates the Server.TTL method which has a data race
(detected with Go's race detector).

Fixes #4

server.go

@@ -22,9 +22,36 @@ const (
 
 var defaultTTL uint32 = 3200
 
+type serverOpts struct {
+ ttl uint32
+}
+
+func applyServerOpts(options ...ServerOption) serverOpts {
+ // Apply default configuration and load supplied options.
+ var conf = serverOpts{
+ ttl: defaultTTL,
+ }
+ for _, o := range options {
+ if o != nil {
+ o(&conf)
+ }
+ }
+ return conf
+}
+
+// ServerOption fills the option struct.
+type ServerOption func(*serverOpts)
+
+// TTL sets the TTL for DNS replies.
+func TTL(ttl uint32) ServerOption {
+ return func(o *serverOpts) {
+ o.ttl = ttl
+ }
+}
+
 // Register a service by given arguments. This call will take the system's hostname
 // and lookup IP by that hostname.
-func Register(instance, service, domain string, port int, text []string, ifaces []net.Interface) (*Server, error) {
+func Register(instance, service, domain string, port int, text []string, ifaces []net.Interface, opts ...ServerOption) (*Server, error) {
  entry := newServiceEntry(instance, service, domain)
  entry.Port = port
  entry.Text = text
@@ -68,7 +95,7 @@ func Register(instance, service, domain string, port int, text []string, ifaces
  return nil, fmt.Errorf("could not determine host IP addresses")
  }
 
- s, err := newServer(ifaces)
+ s, err := newServer(ifaces, applyServerOpts(opts...))
  if err != nil {
  return nil, err
  }
@@ -81,7 +108,7 @@ func Register(instance, service, domain string, port int, text []string, ifaces
 
 // RegisterProxy registers a service proxy. This call will skip the hostname/IP lookup and
 // will use the provided values.
-func RegisterProxy(instance, service, domain string, port int, host string, ips []string, text []string, ifaces []net.Interface) (*Server, error) {
+func RegisterProxy(instance, service, domain string, port int, host string, ips []string, text []string, ifaces []net.Interface, opts ...ServerOption) (*Server, error) {
  entry := newServiceEntry(instance, service, domain)
  entry.Port = port
  entry.Text = text
@@ -124,7 +151,7 @@ func RegisterProxy(instance, service, domain string, port int, host string, ips
  ifaces = listMulticastInterfaces()
  }
 
- s, err := newServer(ifaces)
+ s, err := newServer(ifaces, applyServerOpts(opts...))
  if err != nil {
  return nil, err
  }
@@ -154,7 +181,7 @@ type Server struct {
 }
 
 // Constructs server structure
-func newServer(ifaces []net.Interface) (*Server, error) {
+func newServer(ifaces []net.Interface, opts serverOpts) (*Server, error) {
  ipv4conn, err4 := joinUdp4Multicast(ifaces)
  if err4 != nil {
  log.Printf("[zeroconf] no suitable IPv4 interface: %s", err4.Error())
@@ -172,7 +199,7 @@ func newServer(ifaces []net.Interface) (*Server, error) {
  ipv4conn: ipv4conn,
  ipv6conn: ipv6conn,
  ifaces: ifaces,
- ttl: defaultTTL,
+ ttl: opts.ttl,
  shouldShutdown: make(chan struct{}),
  }
 
@@ -199,6 +226,8 @@ func (s *Server) SetText(text []string) {
 }
 
 // TTL sets the TTL for DNS replies
+//
+// Deprecated: This method is racy. Use the TTL server option instead.
 func (s *Server) TTL(ttl uint32) {
  s.ttl = ttl
 }