From fd482d6510aa8297c2732c1769c90e6f2239a8b1 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Sun, 13 Aug 2023 21:22:58 +0100
Subject: [PATCH] Report MPTCP state through admin socket

---
 src/admin/getpeers.go            | 18 ++++++++++--------
 src/core/api.go                  |  2 ++
 src/core/link_tcp_mptcp_go121.go | 18 +++++++++++++++++-
 src/core/link_tcp_mptcp_other.go |  4 ++++
 4 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/src/admin/getpeers.go b/src/admin/getpeers.go
index c6cd5be48..b6893f794 100644
--- a/src/admin/getpeers.go
+++ b/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"`
 	RXBytes       DataUnit      `json:"bytes_recvd,omitempty"`
 	TXBytes       DataUnit      `json:"bytes_sent,omitempty"`
 	Uptime        float64       `json:"uptime,omitempty"`
@@ -36,14 +37,15 @@ 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 addr := address.AddrForKey(p.Key); addr != nil {
 			peer.PublicKey = hex.EncodeToString(p.Key)
diff --git a/src/core/api.go b/src/core/api.go
index ebc818f53..204368dfc 100644
--- a/src/core/api.go
+++ b/src/core/api.go
@@ -31,6 +31,7 @@ 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
diff --git a/src/core/link_tcp_mptcp_go121.go b/src/core/link_tcp_mptcp_go121.go
index 545273625..ccb928fb2 100644
--- a/src/core/link_tcp_mptcp_go121.go
+++ b/src/core/link_tcp_mptcp_go121.go
@@ -3,7 +3,10 @@
 
 package core
 
-import "net"
+import (
+	"crypto/tls"
+	"net"
+)
 
 func setMPTCPForDialer(d *net.Dialer) {
 	d.SetMultipathTCP(true)
@@ -12,3 +15,16 @@ func setMPTCPForDialer(d *net.Dialer) {
 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:
+		mp, _ := tc.NetConn().(*net.TCPConn).MultipathTCP()
+		return mp
+	default:
+		return false
+	}
+}
diff --git a/src/core/link_tcp_mptcp_other.go b/src/core/link_tcp_mptcp_other.go
index 28bc46c58..600558d96 100644
--- a/src/core/link_tcp_mptcp_other.go
+++ b/src/core/link_tcp_mptcp_other.go
@@ -12,3 +12,7 @@ func setMPTCPForDialer(d *net.Dialer) {
 func setMPTCPForListener(lc *net.ListenConfig) {
 	// Not supported on versions under Go 1.21
 }
+
+func isMPTCP(c net.Conn) bool {
+	return false
+}