From 800ebb39be4f07fa7cf112a2915297706b4ee272 Mon Sep 17 00:00:00 2001
From: Alexey Khit <alexey.khit@gmail.com>
Date: Thu, 15 Sep 2022 09:07:53 +0300
Subject: [PATCH] Adds canditates from domain resolver

---
 cmd/webrtc/candidates.go | 15 +++++----------
 pkg/webrtc/helper.go     | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/cmd/webrtc/candidates.go b/cmd/webrtc/candidates.go
index e33888b3..c614e4f2 100644
--- a/cmd/webrtc/candidates.go
+++ b/cmd/webrtc/candidates.go
@@ -5,7 +5,6 @@ import (
 	"github.com/AlexxIT/go2rtc/pkg/streamer"
 	"github.com/AlexxIT/go2rtc/pkg/webrtc"
 	"github.com/pion/sdp/v3"
-	"strings"
 )
 
 var candidates []string
@@ -32,15 +31,11 @@ func addCanditates(answer string) (string, error) {
 	}
 
 	for _, address := range candidates {
-		if strings.HasPrefix(address, "stun:") {
-			ip, err := webrtc.GetPublicIP()
-			if err != nil {
-				log.Warn().Err(err).Msg("[webrtc] public IP")
-				continue
-			}
-			address = ip.String() + address[4:]
-
-			log.Debug().Str("addr", address).Msg("[webrtc] stun public address")
+		var err error
+		address, err = webrtc.LookupIP(address)
+		if err != nil {
+			log.Warn().Err(err).Msg("[webrtc] candidate")
+			continue
 		}
 
 		cand, err := webrtc.NewCandidate(address)
diff --git a/pkg/webrtc/helper.go b/pkg/webrtc/helper.go
index 8bab3c74..cd1e9cb8 100644
--- a/pkg/webrtc/helper.go
+++ b/pkg/webrtc/helper.go
@@ -1,12 +1,14 @@
 package webrtc
 
 import (
+	"fmt"
 	"github.com/AlexxIT/go2rtc/pkg/streamer"
 	"github.com/pion/ice/v2"
 	"github.com/pion/stun"
 	"github.com/pion/webrtc/v3"
 	"net"
 	"strconv"
+	"strings"
 )
 
 func NewCandidate(address string) (string, error) {
@@ -34,6 +36,31 @@ func NewCandidate(address string) (string, error) {
 	return "candidate:" + cand.Marshal(), nil
 }
 
+func LookupIP(address string) (string, error) {
+	if strings.HasPrefix(address, "stun:") {
+		ip, err := GetPublicIP()
+		if err != nil {
+			return "", err
+		}
+		return ip.String() + address[4:], nil
+	}
+
+	if IsIP(address) {
+		return address, nil
+	}
+
+	i := strings.IndexByte(address, ':')
+	ips, err := net.LookupIP(address[:i])
+	if err != nil {
+		return "", err
+	}
+	if len(ips) == 0 {
+		return "", fmt.Errorf("can't resolve: %s", address)
+	}
+
+	return ips[0].String() + address[i:], nil
+}
+
 // GetPublicIP example from https://github.com/pion/stun
 func GetPublicIP() (net.IP, error) {
 	c, err := stun.Dial("udp", "stun.l.google.com:19302")
@@ -63,6 +90,15 @@ func GetPublicIP() (net.IP, error) {
 	return xorAddr.IP, nil
 }
 
+func IsIP(host string) bool {
+	for _, i := range host {
+		if i >= 'A' {
+			return false
+		}
+	}
+	return true
+}
+
 func MimeType(codec *streamer.Codec) string {
 	switch codec.Name {
 	case streamer.CodecH264: