[tor-commits] [pluggable-transports/snowflake] branch main updated: Use Pion's Setting Engine to reduce Multicast DNS noise

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itchyonion pushed a commit to branch main
in repository pluggable-transports/snowflake.

The following commit(s) were added to refs/heads/main by this push:
     new 9ce1de4  Use Pion's Setting Engine to reduce Multicast DNS noise
9ce1de4 is described below

commit 9ce1de4eee4e23c918c7c5e96666ff5c6ddc654e
Author: Tommaso Gragnato <gragnato.tommaso at icloud.com>
AuthorDate: Sun Aug 14 14:34:57 2022 +0200

    Use Pion's Setting Engine to reduce Multicast DNS noise
    
    https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40123
    
    The purpose of the patch is to prevent Pion from opening the mDNS port,
    thus preventing snowflake from directly leaking .local candidates.
    
    What this doesn't prevent is the resolution of .local candidates
    once they are passed on to the system DNS.
---
 client/lib/webrtc.go   |  6 +++++-
 proxy/lib/snowflake.go | 11 +++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/client/lib/webrtc.go b/client/lib/webrtc.go
index d5264a9..01990e0 100644
--- a/client/lib/webrtc.go
+++ b/client/lib/webrtc.go
@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"git.torproject.org/pluggable-transports/snowflake.git/v2/common/event"
+	"github.com/pion/ice/v2"
 	"github.com/pion/webrtc/v3"
 )
 
@@ -189,7 +190,10 @@ func (c *WebRTCPeer) connect(config *webrtc.Configuration, broker *BrokerChannel
 // after ICE candidate gathering is complete..
 func (c *WebRTCPeer) preparePeerConnection(config *webrtc.Configuration) error {
 	var err error
-	c.pc, err = webrtc.NewPeerConnection(*config)
+	s := webrtc.SettingEngine{}
+	s.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
+	api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
+	c.pc, err = api.NewPeerConnection(*config)
 	if err != nil {
 		log.Printf("NewPeerConnection ERROR: %s", err)
 		return err
diff --git a/proxy/lib/snowflake.go b/proxy/lib/snowflake.go
index 34f8abe..f9bcddb 100644
--- a/proxy/lib/snowflake.go
+++ b/proxy/lib/snowflake.go
@@ -47,6 +47,7 @@ import (
 	"git.torproject.org/pluggable-transports/snowflake.git/v2/common/util"
 	"git.torproject.org/pluggable-transports/snowflake.git/v2/common/websocketconn"
 	"github.com/gorilla/websocket"
+	"github.com/pion/ice/v2"
 	"github.com/pion/webrtc/v3"
 )
 
@@ -355,7 +356,10 @@ func (sf *SnowflakeProxy) makePeerConnectionFromOffer(sdp *webrtc.SessionDescrip
 	dataChan chan struct{},
 	handler func(conn *webRTCConn, remoteAddr net.Addr)) (*webrtc.PeerConnection, error) {
 
-	pc, err := webrtc.NewPeerConnection(config)
+	s := webrtc.SettingEngine{}
+	s.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
+	api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
+	pc, err := api.NewPeerConnection(config)
 	if err != nil {
 		return nil, fmt.Errorf("accept: NewPeerConnection: %s", err)
 	}
@@ -442,7 +446,10 @@ func (sf *SnowflakeProxy) makePeerConnectionFromOffer(sdp *webrtc.SessionDescrip
 func (sf *SnowflakeProxy) makeNewPeerConnection(config webrtc.Configuration,
 	dataChan chan struct{}) (*webrtc.PeerConnection, error) {
 
-	pc, err := webrtc.NewPeerConnection(config)
+	s := webrtc.SettingEngine{}
+	s.SetICEMulticastDNSMode(ice.MulticastDNSModeDisabled)
+	api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
+	pc, err := api.NewPeerConnection(config)
 	if err != nil {
 		return nil, fmt.Errorf("accept: NewPeerConnection: %s", err)
 	}

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