Some rabbit nitpick fixes

packages/relay/internal/common/ice_helper.go

@@ -0,0 +1,53 @@
+package common
+
+import (
+	"log/slog"
+
+	"github.com/pion/webrtc/v4"
+)
+
+// ICEHelper holds webrtc.ICECandidateInit(s) until remote candidate is set for given webrtc.PeerConnection
+// Held candidates should be flushed at the end of negotiation to ensure all are available for connection
+type ICEHelper struct {
+	candidates []webrtc.ICECandidateInit
+	pc         *webrtc.PeerConnection
+}
+
+func NewICEHelper(pc *webrtc.PeerConnection) *ICEHelper {
+	return &ICEHelper{
+		pc:         pc,
+		candidates: make([]webrtc.ICECandidateInit, 0),
+	}
+}
+
+func (ice *ICEHelper) SetPeerConnection(pc *webrtc.PeerConnection) {
+	ice.pc = pc
+}
+
+func (ice *ICEHelper) AddCandidate(c webrtc.ICECandidateInit) {
+	if ice.pc != nil {
+		if ice.pc.RemoteDescription() != nil {
+			// Add immediately if remote is set
+			if err := ice.pc.AddICECandidate(c); err != nil {
+				slog.Error("Failed to add ICE candidate", "err", err)
+			}
+			// Also flush held candidates automatically
+			ice.FlushHeldCandidates()
+		} else {
+			// Hold in slice until remote is set
+			ice.candidates = append(ice.candidates, c)
+		}
+	}
+}
+
+func (ice *ICEHelper) FlushHeldCandidates() {
+	if ice.pc != nil && len(ice.candidates) > 0 {
+		for _, heldCandidate := range ice.candidates {
+			if err := ice.pc.AddICECandidate(heldCandidate); err != nil {
+				slog.Error("Failed to add held ICE candidate", "err", err)
+			}
+		}
+		// Clear the held candidates
+		ice.candidates = make([]webrtc.ICECandidateInit, 0)
+	}
+}