add metric to metadata exchange, but currently left at default 0 value

src/core/link.go

@@ -158,6 +158,8 @@ func (intf *link) handler() (chan struct{}, error) {
 	defer intf.conn.Close()
 	meta := version_getBaseMetadata()
 	meta.key = intf.links.core.public
+	// TODO set meta.metric
+	metric := uint64(meta.metric)
 	metaBytes := meta.encode()
 	// TODO timeouts on send/recv (goroutine for send/recv, channel select w/ timer)
 	var err error
@@ -190,6 +192,9 @@ func (intf *link) handler() (chan struct{}, error) {
 	if !meta.decode(metaBytes) {
 		return nil, errors.New("failed to decode metadata")
 	}
+	if metric < uint64(meta.metric) {
+		metric = uint64(meta.metric)
+	}
 	if !meta.check() {
 		intf.links.core.log.Errorf("Failed to connect to node: %s is incompatible version (local %s, remote %s)",
 			intf.lname,
@@ -250,7 +255,6 @@ func (intf *link) handler() (chan struct{}, error) {
 	intf.links.core.log.Infof("Connected %s: %s, source %s",
 		strings.ToUpper(intf.info.linkType), themString, intf.info.local)
 	// Run the handler
-	var metric uint64 // TODO exchange metric in matadata, use max value
 	err = intf.links.core.PacketConn.HandleConn(ed25519.PublicKey(intf.info.key[:]), intf.conn, metric)
 	// TODO don't report an error if it's just a 'use of closed network connection'
 	if err != nil {

src/core/version.go

@@ -14,6 +14,7 @@ type version_metadata struct {
 	ver  uint8 // 1 byte in this version
 	// Everything after this point potentially depends on the version number, and is subject to change in future versions
 	minorVer uint8 // 1 byte in this version
+	metric   uint8 // 1 byte in this version
 	key      ed25519.PublicKey
 }
 
@@ -31,6 +32,7 @@ func version_getMetaLength() (mlen int) {
 	mlen += 4                     // meta
 	mlen++                        // ver, as long as it's < 127, which it is in this version
 	mlen++                        // minorVer, as long as it's < 127, which it is in this version
+	mlen++                        // metric
 	mlen += ed25519.PublicKeySize // key
 	return
 }
@@ -41,6 +43,7 @@ func (m *version_metadata) encode() []byte {
 	bs = append(bs, m.meta[:]...)
 	bs = append(bs, m.ver)
 	bs = append(bs, m.minorVer)
+	bs = append(bs, m.metric)
 	bs = append(bs, m.key[:]...)
 	if len(bs) != version_getMetaLength() {
 		panic("Inconsistent metadata length")
@@ -57,6 +60,7 @@ func (m *version_metadata) decode(bs []byte) bool {
 	offset += copy(m.meta[:], bs[offset:])
 	m.ver, offset = bs[offset], offset+1
 	m.minorVer, offset = bs[offset], offset+1
+	m.metric, offset = bs[offset], offset+1
 	m.key = append([]byte(nil), bs[offset:]...)
 	return true
 }