From b632c7d49cd7634eb9b58f96fb81f8f289568e9f Mon Sep 17 00:00:00 2001
From: Cecylia Bocovich <cohosh@torproject.org>
Date: Tue, 30 May 2023 15:30:07 -0400
Subject: [PATCH] Workaround for shadow in lieu of AF_NETLINK support

For details, see https://github.com/shadow/shadow/issues/2980
---
 client/lib/webrtc.go | 7 +++++++
 go.mod               | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/client/lib/webrtc.go b/client/lib/webrtc.go
index 7d986d3..fedf299 100644
--- a/client/lib/webrtc.go
+++ b/client/lib/webrtc.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/pion/ice/v2"
+	"github.com/pion/transport/v2/stdnet"
 	"github.com/pion/webrtc/v3"
 	"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/event"
 )
@@ -194,6 +195,12 @@ func (c *WebRTCPeer) preparePeerConnection(config *webrtc.Configuration) error {
 	var err error
 	s := webrtc.SettingEngine{}
 	s.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
+	// Use the SetNet setting https://pkg.go.dev/github.com/pion/webrtc/v3#SettingEngine.SetNet
+	// to get snowflake working in shadow (where the AF_NETLINK family is not implemented).
+	// These two lines of code functionally revert a new change in pion by silently ignoring
+	// when net.Interfaces() fails, rather than throwing an error
+	vnet, _ := stdnet.NewNet()
+	s.SetNet(vnet)
 	api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
 	c.pc, err = api.NewPeerConnection(*config)
 	if err != nil {
diff --git a/go.mod b/go.mod
index 4d64230..9c2087b 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,7 @@ require (
 	github.com/pion/ice/v2 v2.3.8
 	github.com/pion/sdp/v3 v3.0.6
 	github.com/pion/stun v0.6.1
+	github.com/pion/transport/v2 v2.2.1
 	github.com/pion/webrtc/v3 v3.2.11
 	github.com/prometheus/client_golang v1.16.0
 	github.com/prometheus/client_model v0.4.0
@@ -49,7 +50,6 @@ require (
 	github.com/pion/rtp v1.7.13 // indirect
 	github.com/pion/sctp v1.8.7 // indirect
 	github.com/pion/srtp/v2 v2.0.15 // indirect
-	github.com/pion/transport/v2 v2.2.1 // indirect
 	github.com/pion/turn/v2 v2.1.2 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect