Implement EAAS discovery message.

messages.go

@@ -847,3 +847,70 @@ func (m *discoveryMessage) writeTo(w io.Writer) (err error) {
 	}
 	return
 }
+
+type eaasDiscoveryMessage struct {
+	tokenPrefixedMessage
+	Hostname        string
+	SoftwareVersion string
+	URL             string
+	Extra           string // usually just _
+}
+
+var eaasDiscoveryMagic = []byte("EAAS")
+
+func (m *eaasDiscoveryMessage) checkMatch(r *bufio.Reader) (ok bool, err error) {
+	var readMagic []byte
+	if readMagic, err = r.Peek(4); err != nil {
+		return
+	}
+	ok = bytes.Equal(readMagic, discoveryMagic)
+	return
+}
+
+func (m *eaasDiscoveryMessage) readFrom(r io.Reader) (err error) {
+	readMagic := make([]byte, 4)
+	if _, err = r.Read(readMagic); err != nil {
+		return
+	} else if !bytes.Equal(readMagic, discoveryMagic) {
+		err = ErrInvalidMessageReceived
+		return
+	}
+	if err = m.tokenPrefixedMessage.readFrom(r); err != nil {
+		return
+	}
+	if err = readNetworkString(r, &m.Hostname); err != nil {
+		return
+	}
+	if err = readLengthPrefixedNetworkString(r, &m.URL, utf8StringEncoding); err != nil {
+		return
+	}
+	if err = readNetworkString(r, &m.SoftwareVersion); err != nil {
+		return
+	}
+	if err = readNetworkString(r, &m.Extra); err != nil {
+		return
+	}
+	return
+}
+
+func (m *eaasDiscoveryMessage) writeTo(w io.Writer) (err error) {
+	if _, err = w.Write(discoveryMagic); err != nil {
+		return
+	}
+	if err = m.tokenPrefixedMessage.writeTo(w); err != nil {
+		return
+	}
+	if err = writeNetworkString(w, m.Hostname); err != nil {
+		return
+	}
+	if err = writeLengthPrefixedNetworkString(w, m.URL, utf8StringEncoding); err != nil {
+		return
+	}
+	if err = writeNetworkString(w, m.SoftwareVersion); err != nil {
+		return
+	}
+	if err = writeNetworkString(w, m.Extra); err != nil {
+		return
+	}
+	return
+}

messages_test.go

@@ -234,6 +234,39 @@ var testMessages = []struct {
 			Timelines: []float64{6865523.501393173, 7171186.184697615, 0, 0},
 		},
 	},
+	{
+		Name: "EAAS discovery",
+		Bytes: []byte{
+			0x45, 0x41, 0x41, 0x53, 0x01, 0x01, 0x79, 0x9b,
+			0x2d, 0xab, 0xf7, 0xc7, 0x43, 0x63, 0xb4, 0x9c,
+			0x59, 0xe1, 0x91, 0x16, 0x89, 0x9e, 0x00, 0x00,
+			0x00, 0x24, 0x00, 0x69, 0x00, 0x63, 0x00, 0x65,
+			0x00, 0x64, 0x00, 0x72, 0x00, 0x65, 0x00, 0x61,
+			0x00, 0x6d, 0x00, 0x2d, 0x00, 0x66, 0x00, 0x72,
+			0x00, 0x61, 0x00, 0x6d, 0x00, 0x65, 0x00, 0x77,
+			0x00, 0x6f, 0x00, 0x72, 0x00, 0x6b, 0x00, 0x00,
+			0x00, 0x1c, 0x67, 0x72, 0x70, 0x63, 0x3a, 0x2f,
+			0x2f, 0x31, 0x39, 0x32, 0x2e, 0x31, 0x36, 0x38,
+			0x2e, 0x31, 0x38, 0x38, 0x2e, 0x31, 0x32, 0x30,
+			0x3a, 0x35, 0x30, 0x30, 0x31, 0x30, 0x00, 0x00,
+			0x00, 0x20, 0x00, 0x33, 0x00, 0x2e, 0x00, 0x34,
+			0x00, 0x2e, 0x00, 0x30, 0x00, 0x2e, 0x00, 0x66,
+			0x00, 0x36, 0x00, 0x62, 0x00, 0x33, 0x00, 0x64,
+			0x00, 0x63, 0x00, 0x32, 0x00, 0x63, 0x00, 0x32,
+			0x00, 0x30, 0x01, 0x00, 0x00, 0x00, 0x02, 0x00,
+			0x5f,
+		},
+		CreateMessage: func() message { return new(eaasDiscoveryMessage) },
+		Message: &eaasDiscoveryMessage{
+			tokenPrefixedMessage: tokenPrefixedMessage{
+				Token: Token{0x79, 0x9b, 0x2d, 0xab, 0xf7, 0xc7, 0x43, 0x63, 0xb4, 0x9c, 0x59, 0xe1, 0x91, 0x16, 0x89, 0x9e},
+			},
+			Hostname:        "icedream-framework",
+			SoftwareVersion: "3.4.0.f6b3dc2c20",
+			URL:             "grpc://192.168.188.120:50010",
+			Extra:           "_",
+		},
+	},
 }
 
 func Test_Messages_Read(t *testing.T) {

network_string.go

@@ -4,13 +4,17 @@ import (
 	"encoding/binary"
 	"io"
 
+	"golang.org/x/text/encoding"
 	"golang.org/x/text/encoding/unicode"
 )
 
-var networkStringEncoding = unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM)
+var (
+	utf16StringEncoding = unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM)
+	utf8StringEncoding  = unicode.UTF8
+)
 
-func writeNetworkString(w io.Writer, v string) (err error) {
-	converted, err := networkStringEncoding.NewEncoder().Bytes([]byte(v))
+func writeLengthPrefixedNetworkString(w io.Writer, v string, enc encoding.Encoding) (err error) {
+	converted, err := enc.NewEncoder().Bytes([]byte(v))
 	if err != nil {
 		return
 	}
@@ -21,7 +25,7 @@ func writeNetworkString(w io.Writer, v string) (err error) {
 	return
 }
 
-func readNetworkString(r io.Reader, v *string) (err error) {
+func readLengthPrefixedNetworkString(r io.Reader, v *string, enc encoding.Encoding) (err error) {
 	var expectedLength uint32
 	if err = binary.Read(r, binary.BigEndian, &expectedLength); err != nil {
 		return
@@ -38,10 +42,18 @@ func readNetworkString(r io.Reader, v *string) (err error) {
 		}
 		offset += n
 	}
-	vBytes, err := networkStringEncoding.NewDecoder().Bytes(buf)
+	vBytes, err := enc.NewDecoder().Bytes(buf)
 	if err != nil {
 		return
 	}
 	*v = string(vBytes)
 	return
 }
+
+func writeNetworkString(w io.Writer, v string) (err error) {
+	return writeLengthPrefixedNetworkString(w, v, utf16StringEncoding)
+}
+
+func readNetworkString(r io.Reader, v *string) (err error) {
+	return readLengthPrefixedNetworkString(r, v, utf16StringEncoding)
+}