From 1ec0e7540a2b3668d61af4a9fba7a49b46f52a3e Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Sat, 8 Aug 2020 13:44:33 +0200
Subject: [PATCH] Passive ICE TCP.

---
 group/group.go | 23 +++++++++++++++++++++++
 sfu.go         | 14 ++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/group/group.go b/group/group.go
index b2ab024..8f54a8f 100644
--- a/group/group.go
+++ b/group/group.go
@@ -8,6 +8,7 @@ package group
 import (
 	"encoding/json"
 	"log"
+	"net"
 	"os"
 	"path/filepath"
 	"sort"
@@ -136,6 +137,18 @@ func (g *Group) API() *webrtc.API {
 	return groups.api
 }
 
+var tcpListener net.Listener
+
+func StartTCPListener(addr *net.TCPAddr) error {
+	if tcpListener != nil {
+		tcpListener.Close()
+		tcpListener = nil
+	}
+	var err error
+	tcpListener, err = net.ListenTCP("tcp", addr)
+	return err
+}
+
 func Add(name string, desc *description) (*Group, error) {
 	groups.mu.Lock()
 	defer groups.mu.Unlock()
@@ -143,6 +156,16 @@ func Add(name string, desc *description) (*Group, error) {
 	if groups.groups == nil {
 		groups.groups = make(map[string]*Group)
 		s := webrtc.SettingEngine{}
+		if tcpListener != nil {
+			mux := webrtc.NewICETCPMux(nil, tcpListener, 8)
+			s.SetICETCPMux(mux)
+			s.SetNetworkTypes([]webrtc.NetworkType{
+				webrtc.NetworkTypeUDP4,
+				webrtc.NetworkTypeUDP6,
+				webrtc.NetworkTypeTCP4,
+				webrtc.NetworkTypeTCP6,
+			})
+		}
 		m := webrtc.MediaEngine{}
 		m.RegisterCodec(webrtc.NewRTPVP8CodecExt(
 			webrtc.DefaultPayloadTypeVP8, 90000,
diff --git a/sfu.go b/sfu.go
index 7e57ab4..a9f8d10 100644
--- a/sfu.go
+++ b/sfu.go
@@ -8,6 +8,7 @@ package main
 import (
 	"flag"
 	"log"
+	"net"
 	"os"
 	"os/signal"
 	"path/filepath"
@@ -22,10 +23,14 @@ import (
 
 func main() {
 	var cpuprofile, memprofile, mutexprofile, httpAddr, dataDir string
+	var tcpPort int
 
 	flag.StringVar(&httpAddr, "http", ":8443", "web server `address`")
 	flag.StringVar(&webserver.StaticRoot, "static", "./static/",
 		"web server root `directory`")
+	flag.IntVar(&tcpPort, "tcp-port", -1,
+		"TCP listener `port`.  If 0, an ephemeral port is used.\n"+
+			"If -1, the TCP listerer is disabled")
 	flag.StringVar(&dataDir, "data", "./data/",
 		"data `directory`")
 	flag.StringVar(&group.Directory, "groups", "./groups/",
@@ -80,6 +85,15 @@ func main() {
 
 	group.IceFilename = filepath.Join(dataDir, "ice-servers.json")
 
+	if tcpPort >= 0 {
+		err := group.StartTCPListener(&net.TCPAddr{
+			Port: tcpPort,
+		})
+		if err != nil {
+			log.Fatalf("Couldn't start ICE TCP: %v", err)
+		}
+	}
+
 	go group.ReadPublicGroups()
 
 	serverDone := make(chan struct{})