Add support for Multipath TCP

Author: neilalexander

src/admin/getpeers.go

@@ -24,6 +24,7 @@ type PeerEntry struct {
 	PublicKey     string        `json:"key"`
 	Port          uint64        `json:"port"`
 	Priority      uint64        `json:"priority"`
+	Multipath     bool          `json:"multipath,omitempty"`
 	RXBytes       DataUnit      `json:"bytes_recvd,omitempty"`
 	TXBytes       DataUnit      `json:"bytes_sent,omitempty"`
 	Uptime        float64       `json:"uptime,omitempty"`
@@ -37,14 +38,15 @@ func (a *AdminSocket) getPeersHandler(req *GetPeersRequest, res *GetPeersRespons
 	res.Peers = make([]PeerEntry, 0, len(peers))
 	for _, p := range peers {
 		peer := PeerEntry{
-			Port:     p.Port,
-			Up:       p.Up,
-			Inbound:  p.Inbound,
-			Priority: uint64(p.Priority), // can't be uint8 thanks to gobind
-			URI:      p.URI,
-			RXBytes:  DataUnit(p.RXBytes),
-			TXBytes:  DataUnit(p.TXBytes),
-			Uptime:   p.Uptime.Seconds(),
+			Port:      p.Port,
+			Up:        p.Up,
+			Inbound:   p.Inbound,
+			Priority:  uint64(p.Priority), // can't be uint8 thanks to gobind
+			Multipath: p.Multipath,
+			URI:       p.URI,
+			RXBytes:   DataUnit(p.RXBytes),
+			TXBytes:   DataUnit(p.TXBytes),
+			Uptime:    p.Uptime.Seconds(),
 		}
 		if p.Latency > 0 {
 			peer.Latency = p.Latency

src/core/api.go

@@ -30,6 +30,7 @@ type PeerInfo struct {
 	Coords        []uint64
 	Port          uint64
 	Priority      uint8
+	Multipath     bool
 	RXBytes       uint64
 	TXBytes       uint64
 	Uptime        time.Duration
@@ -87,6 +88,7 @@ func (c *Core) GetPeers() []PeerInfo {
 				peerinfo.RXBytes = atomic.LoadUint64(&c.rx)
 				peerinfo.TXBytes = atomic.LoadUint64(&c.tx)
 				peerinfo.Uptime = time.Since(c.up)
+				peerinfo.Multipath = isMPTCP(c)
 			}
 			if p, ok := conns[conn]; ok {
 				peerinfo.Key = p.Key

src/core/link_tcp.go

@@ -27,6 +27,7 @@ func (l *links) newLinkTCP() *linkTCP {
 		_listeners: map[*Listener]context.CancelFunc{},
 	}
 	lt.listenconfig.Control = lt.tcpContext
+	setMPTCPForListener(lt.listenconfig)
 	return lt
 }
 
@@ -112,6 +113,7 @@ func (l *linkTCP) dialerFor(dst *net.TCPAddr, sintf string) (*net.Dialer, error)
 		KeepAlive: -1,
 		Control:   l.tcpContext,
 	}
+	setMPTCPForDialer(dialer)
 	if sintf != "" {
 		dialer.Control = l.getControl(sintf)
 		ief, err := net.InterfaceByName(sintf)

src/core/link_tcp_mptcp.go

@@ -0,0 +1,30 @@
+package core
+
+import (
+	"crypto/tls"
+	"net"
+)
+
+func setMPTCPForDialer(d *net.Dialer) {
+	d.SetMultipathTCP(true)
+}
+
+func setMPTCPForListener(lc *net.ListenConfig) {
+	lc.SetMultipathTCP(true)
+}
+
+func isMPTCP(c net.Conn) bool {
+	switch tc := c.(type) {
+	case *net.TCPConn:
+		mp, _ := tc.MultipathTCP()
+		return mp
+	case *tls.Conn:
+		if tc, ok := tc.NetConn().(*net.TCPConn); ok {
+			mp, _ := tc.MultipathTCP()
+			return mp
+		}
+		return false
+	default:
+		return false
+	}
+}

src/core/link_tls.go

@@ -30,6 +30,7 @@ func (l *links) newLinkTLS(tcp *linkTCP) *linkTLS {
 		config:     l.core.config.tls.Clone(),
 		_listeners: map[*Listener]context.CancelFunc{},
 	}
+	setMPTCPForListener(lt.listener)
 	return lt
 }