From 6e0b7c7e48150c9688b8e3cfcc6b341c02181fd3 Mon Sep 17 00:00:00 2001
From: ZHENK <chengzhenyang@gmail.com>
Date: Wed, 9 Dec 2020 19:00:01 +1300
Subject: [PATCH] Pass nil candidate into pion/ice

Pass empty string candidate.Candidate into pion/ice to handle.

Co-authored-by: JooYoung <qkdlql@naver.com>
---
 peerconnection.go      | 17 ++++++++++++++++-
 peerconnection_test.go | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/peerconnection.go b/peerconnection.go
index dae2ff7b89f..48a1409e959 100644
--- a/peerconnection.go
+++ b/peerconnection.go
@@ -1454,13 +1454,28 @@ func (pc *PeerConnection) RemoteDescription() *SessionDescription {
 }
 
 // AddICECandidate accepts an ICE candidate string and adds it
-// to the existing set of candidates
+// to the existing set of candidates.
+// If ICE candidate string is empty, do not adds it to the existing
+// set of candidates
 func (pc *PeerConnection) AddICECandidate(candidate ICECandidateInit) error {
 	if pc.RemoteDescription() == nil {
 		return &rtcerr.InvalidStateError{Err: ErrNoRemoteDescription}
 	}
 
 	candidateValue := strings.TrimPrefix(candidate.Candidate, "candidate:")
+
+	if candidateValue == "" {
+		agent := pc.iceTransport.gatherer.getAgent()
+		if agent == nil {
+			return fmt.Errorf("%w: unable to add remote candidates", errICEAgentNotExist)
+		}
+
+		err := agent.AddRemoteCandidate(nil)
+		if err != nil {
+			return err
+		}
+	}
+
 	c, err := ice.UnmarshalCandidate(candidateValue)
 	if err != nil {
 		return err
diff --git a/peerconnection_test.go b/peerconnection_test.go
index 0a8ac8afc1a..89f598d7ec1 100644
--- a/peerconnection_test.go
+++ b/peerconnection_test.go
@@ -276,6 +276,43 @@ func TestSetRemoteDescription(t *testing.T) {
 	}
 }
 
+func TestEmptyCandidate(t *testing.T) {
+	testCases := []struct {
+		ICECandidate ICECandidateInit
+		expectError  bool
+	}{
+		{ICECandidateInit{"", nil, nil, nil}, false},
+		{ICECandidateInit{
+			"211962667 1 udp 2122194687 10.0.3.1 40864 typ host generation 0",
+			nil, nil, nil,
+		}, false},
+		{ICECandidateInit{
+			"1234567",
+			nil, nil, nil,
+		}, true},
+	}
+
+	for i, testCase := range testCases {
+		peerConn, err := NewPeerConnection(Configuration{})
+		if err != nil {
+			t.Errorf("Case %d: got error: %v", i, err)
+		}
+
+		err = peerConn.SetRemoteDescription(SessionDescription{Type: SDPTypeOffer, SDP: minimalOffer})
+		if err != nil {
+			t.Errorf("Case %d: got error: %v", i, err)
+		}
+
+		if testCase.expectError {
+			assert.Error(t, peerConn.AddICECandidate(testCase.ICECandidate))
+		} else {
+			assert.NoError(t, peerConn.AddICECandidate(testCase.ICECandidate))
+		}
+
+		assert.NoError(t, peerConn.Close())
+	}
+}
+
 func TestCreateOfferAnswer(t *testing.T) {
 	offerPeerConn, err := NewPeerConnection(Configuration{})
 	assert.NoError(t, err)