refactor: describe transport delivery features

internal/transport/datachannel/transport.go

@@ -9,6 +9,8 @@ import (
 	"github.com/openlibrecommunity/olcrtc/internal/transport"
 )
 
+const defaultMaxPayloadSize = 12 * 1024
+
 type streamTransport struct {
 	stream carrier.ByteStream
 }
@@ -79,3 +81,13 @@ func (p *streamTransport) WatchConnection(ctx context.Context) {
 func (p *streamTransport) CanSend() bool {
 	return p.stream.CanSend()
 }
+
+// Features describes the current datachannel transport semantics.
+func (p *streamTransport) Features() transport.Features {
+	return transport.Features{
+		Reliable:        true,
+		Ordered:         true,
+		MessageOriented: true,
+		MaxPayloadSize:  defaultMaxPayloadSize,
+	}
+}

internal/transport/transport.go

@@ -11,6 +11,14 @@ var (
 	ErrTransportNotFound = errors.New("transport not found")
 )
 
+// Features describes the delivery semantics of a transport.
+type Features struct {
+	Reliable        bool
+	Ordered         bool
+	MessageOriented bool
+	MaxPayloadSize  int
+}
+
 // Transport defines a byte transport independent of the underlying carrier.
 type Transport interface {
 	Connect(ctx context.Context) error
@@ -21,6 +29,7 @@ type Transport interface {
 	SetEndedCallback(cb func(string))
 	WatchConnection(ctx context.Context)
 	CanSend() bool
+	Features() Features
 }
 
 // Config holds common transport configuration.