snapshot of https://github.com/pion/webrtc.git (main, 2026-09-15; blobs > 131072B omitted)

sdpsemantics.go

@@ -0,0 +1,76 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package webrtc
+
+import (
+	"encoding/json"
+)
+
+// SDPSemantics determines which style of SDP offers and answers
+// can be used.
+type SDPSemantics int
+
+const (
+	// SDPSemanticsUnifiedPlan uses unified-plan offers and answers
+	// (the default in Chrome since M72)
+	// https://tools.ietf.org/html/draft-roach-mmusic-unified-plan-00
+	SDPSemanticsUnifiedPlan SDPSemantics = iota
+
+	// SDPSemanticsPlanB uses plan-b offers and answers
+	// NB: This format should be considered deprecated
+	// https://tools.ietf.org/html/draft-uberti-rtcweb-plan-00
+	SDPSemanticsPlanB
+
+	// SDPSemanticsUnifiedPlanWithFallback prefers unified-plan
+	// offers and answers, but will respond to a plan-b offer
+	// with a plan-b answer.
+	SDPSemanticsUnifiedPlanWithFallback
+)
+
+const (
+	sdpSemanticsUnifiedPlanWithFallback = "unified-plan-with-fallback"
+	sdpSemanticsUnifiedPlan             = "unified-plan"
+	sdpSemanticsPlanB                   = "plan-b"
+)
+
+func newSDPSemantics(raw string) SDPSemantics {
+	switch raw {
+	case sdpSemanticsPlanB:
+		return SDPSemanticsPlanB
+	case sdpSemanticsUnifiedPlanWithFallback:
+		return SDPSemanticsUnifiedPlanWithFallback
+	default:
+		return SDPSemanticsUnifiedPlan
+	}
+}
+
+func (s SDPSemantics) String() string {
+	switch s {
+	case SDPSemanticsUnifiedPlanWithFallback:
+		return sdpSemanticsUnifiedPlanWithFallback
+	case SDPSemanticsUnifiedPlan:
+		return sdpSemanticsUnifiedPlan
+	case SDPSemanticsPlanB:
+		return sdpSemanticsPlanB
+	default:
+		return ErrUnknownType.Error()
+	}
+}
+
+// UnmarshalJSON parses the JSON-encoded data and stores the result.
+func (s *SDPSemantics) UnmarshalJSON(b []byte) error {
+	var val string
+	if err := json.Unmarshal(b, &val); err != nil {
+		return err
+	}
+
+	*s = newSDPSemantics(val)
+
+	return nil
+}
+
+// MarshalJSON returns the JSON encoding.
+func (s SDPSemantics) MarshalJSON() ([]byte, error) {
+	return json.Marshal(s.String())
+}