Comment new parseLiteners function.

server.go

@@ -766,18 +766,22 @@ func (s *server) ScheduleShutdown(duration time.Duration) {
 	}()
 }
 
+// parseListeners splits the list of listen addresses passed in addrs into
+// IPv4 and IPv6 slices and returns them.  This allows easy creation of the
+// listeners on the correct interface "tcp4" and "tcp6".  It also, properly
+// detects addresses which apply to "all interfaces" and adds the address to
+// both slices.
 func parseListeners(addrs []string) ([]string, []string, error) {
 	ipv4ListenAddrs := make([]string, 0, len(cfg.Listeners)*2)
 	ipv6ListenAddrs := make([]string, 0, len(cfg.Listeners)*2)
 	for _, addr := range cfg.Listeners {
 		host, _, err := net.SplitHostPort(addr)
 		if err != nil {
-			// shouldn't happen, should have already been normalized.
+			// Shouldn't happen due to already being normalized.
 			return nil, nil, err
 		}
 
-		// Empty host or host of * on plan9 is both IPv4 and
+		// Empty host or host of * on plan9 is both IPv4 and IPv6.
-		// IPv6.
 		if host == "" || (host == "*" && runtime.GOOS == "plan9") {
 			ipv4ListenAddrs = append(ipv4ListenAddrs, addr)
 			ipv6ListenAddrs = append(ipv6ListenAddrs, addr)
@@ -790,6 +794,8 @@ func parseListeners(addrs []string) ([]string, []string, error) {
 			return nil, nil, err
 		}
 
+		// To4 returns nil when the IP is not an IPv4 address, so use
+		// this determine the address type.
 		if ip.To4() == nil {
 			ipv6ListenAddrs = append(ipv6ListenAddrs, addr)
 		} else {