feat: add ICE servers and local IP address returned by the API to fix connectivity issues behind NAT

cloud.go

@@ -7,13 +7,14 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
-	"github.com/coder/websocket/wsjson"
 	"time"
 
+	"github.com/coder/websocket/wsjson"
+
 	"github.com/coreos/go-oidc/v3/oidc"
 
-	"github.com/gin-gonic/gin"
 	"github.com/coder/websocket"
+	"github.com/gin-gonic/gin"
 )
 
 type CloudRegisterRequest struct {
@@ -187,7 +188,11 @@ func handleSessionRequest(ctx context.Context, c *websocket.Conn, req WebRTCSess
 		return fmt.Errorf("google identity mismatch")
 	}
 
-	session, err := newSession()
+	session, err := newSession(SessionConfig{
+		ICEServers: req.ICEServers,
+		LocalIP:    req.IP,
+		IsCloud:    true,
+	})
 	if err != nil {
 		_ = wsjson.Write(context.Background(), c, gin.H{"error": err})
 		return err

web.go

@@ -17,8 +17,10 @@ import (
 var staticFiles embed.FS
 
 type WebRTCSessionRequest struct {
-	Sd         string `json:"sd"`
-	OidcGoogle string `json:"OidcGoogle,omitempty"`
+	Sd         string   `json:"sd"`
+	OidcGoogle string   `json:"OidcGoogle,omitempty"`
+	IP         string   `json:"ip,omitempty"`
+	ICEServers []string `json:"iceServers,omitempty"`
 }
 
 type SetPasswordRequest struct {
@@ -116,7 +118,7 @@ func handleWebRTCSession(c *gin.Context) {
 		return
 	}
 
-	session, err := newSession()
+	session, err := newSession(SessionConfig{})
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err})
 		return

webrtc.go

@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"net"
 	"strings"
 
 	"github.com/pion/webrtc/v4"
@@ -19,6 +20,12 @@ type Session struct {
 	shouldUmountVirtualMedia bool
 }
 
+type SessionConfig struct {
+	ICEServers []string
+	LocalIP    string
+	IsCloud    bool
+}
+
 func (s *Session) ExchangeOffer(offerStr string) (string, error) {
 	b, err := base64.StdEncoding.DecodeString(offerStr)
 	if err != nil {
@@ -61,9 +68,29 @@ func (s *Session) ExchangeOffer(offerStr string) (string, error) {
 	return base64.StdEncoding.EncodeToString(localDescription), nil
 }
 
-func newSession() (*Session, error) {
-	peerConnection, err := webrtc.NewPeerConnection(webrtc.Configuration{
-		ICEServers: []webrtc.ICEServer{{}},
+func newSession(config SessionConfig) (*Session, error) {
+	webrtcSettingEngine := webrtc.SettingEngine{}
+	iceServer := webrtc.ICEServer{}
+
+	if config.IsCloud {
+		if config.ICEServers == nil {
+			fmt.Printf("ICE Servers not provided by cloud")
+		} else {
+			iceServer.URLs = config.ICEServers
+			fmt.Printf("Using ICE Servers provided by cloud: %v\n", iceServer.URLs)
+		}
+
+		if config.LocalIP == "" || net.ParseIP(config.LocalIP) == nil {
+			fmt.Printf("Local IP address %v not provided or invalid, won't set NAT1To1IPs\n", config.LocalIP)
+		} else {
+			webrtcSettingEngine.SetNAT1To1IPs([]string{config.LocalIP}, webrtc.ICECandidateTypeSrflx)
+			fmt.Printf("Setting NAT1To1IPs to %s\n", config.LocalIP)
+		}
+	}
+
+	api := webrtc.NewAPI(webrtc.WithSettingEngine(webrtcSettingEngine))
+	peerConnection, err := api.NewPeerConnection(webrtc.Configuration{
+		ICEServers: []webrtc.ICEServer{iceServer},
 	})
 	if err != nil {
 		return nil, err