Set the default NTP server to the NTS-KE IP we connected to

This ensure that NTP server default is the same as the NTS-KE server
we're doing key exchange with. Case in point is a setup where NTS-KE
FQDN has multiple A records, and does not do server negotiation to point
us in the right direction.

ntske.go

@@ -335,16 +335,13 @@ func Connect(hostport string, config *tls.Config, debug bool) (*KeyExchange, err
 	ke.Debug = debug
 	ke.hostport = hostport
 
-	host, _, err := net.SplitHostPort(ke.hostport)
+	_, _, err := net.SplitHostPort(ke.hostport)
 	if err != nil {
 		if !strings.Contains(err.Error(), "missing port in address") {
 			return nil, err
 		}
-		host = ke.hostport
 		ke.hostport = net.JoinHostPort(ke.hostport, strconv.Itoa(DEFAULT_NTSKE_PORT))
 	}
-	ke.Meta.Server = host // Default to same server for NTP as NTS
-	ke.Meta.Port = DEFAULT_NTP_PORT
 
 	if ke.Debug {
 		fmt.Printf("Connecting to KE server %v\n", ke.hostport)
@@ -356,6 +353,18 @@ func Connect(hostport string, config *tls.Config, debug bool) (*KeyExchange, err
 		return nil, err
 	}
 
+	// Set default NTP server to the IP resolved and connected to for NTS-KE.
+	// Handles multiple A records & possible lack of NTPv4 Server Negotiation.
+	ke.Meta.Server, _, err = net.SplitHostPort(ke.Conn.RemoteAddr().String())
+	if err != nil {
+		return nil, fmt.Errorf("unexpected remoteaddr issue: %s", err)
+	}
+	ke.Meta.Port = DEFAULT_NTP_PORT
+
+	if ke.Debug {
+		fmt.Printf("Using resolved KE server as NTP default: %v\n",
+			net.JoinHostPort(ke.Meta.Server, strconv.Itoa(int(ke.Meta.Port))))
+	}
 	ke.reader = bufio.NewReader(ke.Conn)
 
 	state := ke.Conn.ConnectionState()
@@ -476,10 +485,7 @@ func (ke *KeyExchange) Read() error {
 
 		switch msg.Type {
 		case RecEom:
-			// Check that we have complete data. It's OK
-			// if we don't fill in meta.Server --- this
-			// means the client should use the same IP
-			// address as the NTS-KE server.
+			// Check that we have complete data.
 			// if len(ke.Meta.Cookie) == 0 || ke.Meta.Algo == 0 {
 			// 	return errors.New("incomplete data")
 			// }
@@ -519,12 +525,18 @@ func (ke *KeyExchange) Read() error {
 				return errors.New("buffer overrun")
 			}
 			ke.Meta.Server = string(address)
+			if ke.Debug {
+				fmt.Printf("(got negotiated NTP server: %v)\n", ke.Meta.Server)
+			}
 
 		case RecPort:
 			err := binary.Read(ke.reader, binary.BigEndian, &ke.Meta.Port)
 			if err != nil {
 				return errors.New("buffer overrun")
 			}
+			if ke.Debug {
+				fmt.Printf("(got negotiated NTP port: %v)\n", ke.Meta.Port)
+			}
 
 		default:
 			if critical {