From 14b934a78073117aa525aecb5e7fa00ece6d2f4e Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Wed, 17 Apr 2024 09:45:10 +0530
Subject: [PATCH] Log ICE candidates to debug TCP connection issues. (#2658)

---
 pkg/rtc/participant_signal.go |  4 ++++
 pkg/rtc/transport.go          | 24 +++++++++++++++++++++++-
 pkg/rtc/transportmanager.go   | 15 ---------------
 3 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/pkg/rtc/participant_signal.go b/pkg/rtc/participant_signal.go
index d4dbafa35..dc0a2405a 100644
--- a/pkg/rtc/participant_signal.go
+++ b/pkg/rtc/participant_signal.go
@@ -22,6 +22,7 @@ import (
 	"github.com/pion/webrtc/v3"
 
 	"github.com/livekit/protocol/livekit"
+	"github.com/livekit/protocol/logger"
 	"github.com/livekit/psrpc"
 
 	"github.com/livekit/livekit-server/pkg/routing"
@@ -254,6 +255,9 @@ func (p *ParticipantImpl) sendDisconnectUpdatesForReconnect() error {
 func (p *ParticipantImpl) sendICECandidate(c *webrtc.ICECandidate, target livekit.SignalTarget) error {
 	trickle := ToProtoTrickle(c.ToJSON())
 	trickle.Target = target
+
+	p.params.Logger.Debugw("sending ICE candidate", "transport", target, "trickle", logger.Proto(trickle))
+
 	return p.writeMessage(&livekit.SignalResponse{
 		Message: &livekit.SignalResponse_Trickle{
 			Trickle: trickle,
diff --git a/pkg/rtc/transport.go b/pkg/rtc/transport.go
index c4e496be5..b4cc64b0b 100644
--- a/pkg/rtc/transport.go
+++ b/pkg/rtc/transport.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/bep/debounce"
 	"github.com/pion/dtls/v2/pkg/crypto/elliptic"
+	"github.com/pion/ice/v2"
 	"github.com/pion/interceptor"
 	"github.com/pion/interceptor/pkg/cc"
 	"github.com/pion/interceptor/pkg/gcc"
@@ -702,6 +703,19 @@ func (t *PCTransport) SetPreferTCP(preferTCP bool) {
 }
 
 func (t *PCTransport) AddICECandidate(candidate webrtc.ICECandidateInit) {
+	if !t.params.Config.UseMDNS {
+		candidateValue := strings.TrimPrefix(candidate.Candidate, "candidate:")
+		if candidateValue != "" {
+			candidate, err := ice.UnmarshalCandidate(candidateValue)
+			if err != nil {
+				t.params.Logger.Errorw("failed to parse ice candidate", err)
+			} else if strings.HasSuffix(candidate.Address(), ".local") {
+				t.params.Logger.Debugw("ignoring mDNS candidate", "candidate", candidateValue)
+				return
+			}
+		}
+	}
+
 	t.postEvent(event{
 		signal: signalRemoteICECandidate,
 		data:   &candidate,
@@ -1314,6 +1328,7 @@ func (t *PCTransport) localDescriptionSent() error {
 
 	for _, c := range cachedLocalCandidates {
 		if err := t.params.Handler.OnICECandidate(c, t.params.Transport); err != nil {
+			t.params.Logger.Warnw("failed to send cached ICE candidate", err, "candidate", c)
 			return err
 		}
 	}
@@ -1347,7 +1362,12 @@ func (t *PCTransport) handleLocalICECandidate(e event) error {
 		return nil
 	}
 
-	return t.params.Handler.OnICECandidate(c, t.params.Transport)
+	if err := t.params.Handler.OnICECandidate(c, t.params.Transport); err != nil {
+		t.params.Logger.Warnw("failed to send ICE candidate", err, "candidate", c)
+		return err
+	}
+
+	return nil
 }
 
 func (t *PCTransport) handleRemoteICECandidate(e event) error {
@@ -1370,6 +1390,7 @@ func (t *PCTransport) handleRemoteICECandidate(e event) error {
 	}
 
 	if err := t.pc.AddICECandidate(*c); err != nil {
+		t.params.Logger.Warnw("failed to add cached ICE candidate", err, "candidate", c)
 		return errors.Wrap(err, "add ice candidate failed")
 	}
 
@@ -1605,6 +1626,7 @@ func (t *PCTransport) setRemoteDescription(sd webrtc.SessionDescription) error {
 
 	for _, c := range t.pendingRemoteCandidates {
 		if err := t.pc.AddICECandidate(*c); err != nil {
+			t.params.Logger.Warnw("failed to add cached ICE candidate", err, "candidate", c)
 			return errors.Wrap(err, "add ice candidate failed")
 		}
 	}
diff --git a/pkg/rtc/transportmanager.go b/pkg/rtc/transportmanager.go
index 3bc666b57..64569f196 100644
--- a/pkg/rtc/transportmanager.go
+++ b/pkg/rtc/transportmanager.go
@@ -16,11 +16,9 @@ package rtc
 
 import (
 	"math/bits"
-	"strings"
 	"sync"
 	"time"
 
-	"github.com/pion/ice/v2"
 	"github.com/pion/rtcp"
 	"github.com/pion/sdp/v3"
 	"github.com/pion/webrtc/v3"
@@ -372,19 +370,6 @@ func (t *TransportManager) HandleAnswer(answer webrtc.SessionDescription) {
 
 // AddICECandidate adds candidates for remote peer
 func (t *TransportManager) AddICECandidate(candidate webrtc.ICECandidateInit, target livekit.SignalTarget) {
-	if !t.params.Config.UseMDNS {
-		candidateValue := strings.TrimPrefix(candidate.Candidate, "candidate:")
-		if candidateValue != "" {
-			candidate, err := ice.UnmarshalCandidate(candidateValue)
-			if err != nil {
-				t.params.Logger.Errorw("failed to parse ice candidate", err)
-			} else if strings.HasSuffix(candidate.Address(), ".local") {
-				t.params.Logger.Debugw("ignoring mDNS candidate", "candidate", candidateValue, "target", target)
-				return
-			}
-		}
-	}
-
 	switch target {
 	case livekit.SignalTarget_PUBLISHER:
 		t.publisher.AddICECandidate(candidate)