Update WebRTC server operation in closed docker containers

internal/webrtc/candidates.go

@@ -7,6 +7,7 @@ import (
 	"github.com/AlexxIT/go2rtc/internal/api/ws"
 	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/AlexxIT/go2rtc/pkg/webrtc"
+	"github.com/AlexxIT/go2rtc/pkg/xnet"
 	pion "github.com/pion/webrtc/v3"
 )
 
@@ -73,6 +74,11 @@ func FilterCandidate(candidate *pion.ICECandidate) bool {
 		return false
 	}
 
+	// remove any Docker-like IP from candidates
+	if ip := net.ParseIP(candidate.Address); ip != nil && xnet.Docker.Contains(ip) {
+		return false
+	}
+
 	// host candidate should be in the hosts list
 	if candidate.Typ == pion.ICECandidateTypeHost && filters.Candidates != nil {
 		if !core.Contains(filters.Candidates, candidate.Address) {

internal/webrtc/webrtc.go

@@ -24,7 +24,7 @@ func Init() {
 		} `yaml:"webrtc"`
 	}
 
-	cfg.Mod.Listen = ":8555/tcp"
+	cfg.Mod.Listen = ":8555"
 	cfg.Mod.IceServers = []pion.ICEServer{
 		{URLs: []string{"stun:stun.l.google.com:19302"}},
 	}

pkg/mdns/client.go

@@ -10,7 +10,7 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/AlexxIT/go2rtc/pkg/net2"
+	"github.com/AlexxIT/go2rtc/pkg/xnet"
 	"github.com/miekg/dns" // awesome library for parsing mDNS records
 )
 
@@ -170,7 +170,9 @@ type Browser struct {
 // Receiver will get multicast responses on senders requests.
 func (b *Browser) ListenMulticastUDP() error {
 	// 1. Collect IPv4 interfaces
-	nets, err := IPNets()
+	nets, err := xnet.IPNets(func(ip net.IP) bool {
+		return !xnet.Docker.Contains(ip)
+	})
 	if err != nil {
 		return err
 	}
@@ -370,30 +372,3 @@ func NewServiceEntries(msg *dns.Msg, ip net.IP) (entries []*ServiceEntry) {
 
 	return
 }
-
-func IPNets() ([]*net.IPNet, error) {
-	intfs, err := net.Interfaces()
-	if err != nil {
-		return nil, err
-	}
-
-	var nets []*net.IPNet
-
-	for _, intf := range intfs {
-		if intf.Flags&net.FlagUp == 0 || intf.Flags&net.FlagLoopback != 0 {
-			continue
-		}
-
-		addrs, _ := intf.Addrs()
-		for _, addr := range addrs {
-			switch v := addr.(type) {
-			case *net.IPNet:
-				if ip := v.IP.To4(); ip != nil && !net2.Docker.Contains(ip) {
-					nets = append(nets, v)
-				}
-			}
-		}
-	}
-
-	return nets, nil
-}

pkg/webrtc/api.go

@@ -4,7 +4,7 @@ import (
 	"net"
 
 	"github.com/AlexxIT/go2rtc/pkg/core"
-	"github.com/AlexxIT/go2rtc/pkg/net2"
+	"github.com/AlexxIT/go2rtc/pkg/xnet"
 	"github.com/pion/ice/v2"
 	"github.com/pion/interceptor"
 	"github.com/pion/webrtc/v3"
@@ -20,6 +20,7 @@ func NewAPI() (*webrtc.API, error) {
 
 type Filters struct {
 	Candidates []string `yaml:"candidates"`
+	Loopback   bool     `yaml:"loopback"`
 	Interfaces []string `yaml:"interfaces"`
 	IPs        []string `yaml:"ips"`
 	Networks   []string `yaml:"networks"`
@@ -46,6 +47,10 @@ func NewServerAPI(network, address string, filters *Filters) (*webrtc.API, error
 	// fix https://github.com/pion/webrtc/pull/2407
 	s.SetDTLSInsecureSkipHelloVerify(true)
 
+	if filters != nil && filters.Loopback {
+		s.SetIncludeLoopbackCandidate(true)
+	}
+
 	var interfaceFilter func(name string) bool
 	if filters != nil && filters.Interfaces != nil {
 		interfaceFilter = func(name string) bool {
@@ -62,9 +67,14 @@ func NewServerAPI(network, address string, filters *Filters) (*webrtc.API, error
 			return core.Contains(filters.IPs, ip.String())
 		}
 	} else {
-		// default ips - all, except loopback and docker
+		// try filter all Docker-like interfaces
 		ipFilter = func(ip net.IP) bool {
-			return !net2.Docker.Contains(ip)
+			return !xnet.Docker.Contains(ip)
+		}
+		// if there are no such interfaces - disable the filter
+		// the user will need to enable port forwarding
+		if nets, _ := xnet.IPNets(ipFilter); len(nets) == 0 {
+			ipFilter = nil
 		}
 	}
 	s.SetIPFilter(ipFilter)
@@ -109,7 +119,7 @@ func NewServerAPI(network, address string, filters *Filters) (*webrtc.API, error
 		if network == "" || network == "udp" {
 			// UDPMuxDefault should not listening on unspecified address, use NewMultiUDPMuxFromPort instead
 			var udpMux ice.UDPMux
-			if port := net2.ParseUnspecifiedPort(address); port != 0 {
+			if port := xnet.ParseUnspecifiedPort(address); port != 0 {
 				var networks []ice.NetworkType
 				for _, ntype := range networkTypes {
 					networks = append(networks, ice.NetworkType(ntype))

pkg/xnet/net.go

@@ -1,4 +1,4 @@
-package net2
+package xnet
 
 import (
 	"net"
@@ -30,3 +30,35 @@ func ParseUnspecifiedPort(address string) int {
 	i, _ := strconv.Atoi(port)
 	return i
 }
+
+func IPNets(ipFilter func(ip net.IP) bool) ([]*net.IPNet, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+
+	var nets []*net.IPNet
+
+	for _, iface := range ifaces {
+		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+
+		addrs, _ := iface.Addrs() // range on nil slice is OK
+		for _, addr := range addrs {
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip := v.IP.To4()
+				if ip == nil {
+					continue
+				}
+				if ipFilter != nil && !ipFilter(ip) {
+					continue
+				}
+				nets = append(nets, v)
+			}
+		}
+	}
+
+	return nets, nil
+}