refactor: make link selectable at runtime

cmd/olcrtc/main.go

@@ -18,6 +18,7 @@ import (
 
 type config struct {
 	mode           string
+	link           string
 	transport      string
 	carrier        string
 	roomID         string
@@ -83,6 +84,7 @@ func parseFlags() config {
 	cfg := config{}
 
 	flag.StringVar(&cfg.mode, "mode", "", "Mode: srv or cnc")
+	flag.StringVar(&cfg.link, "link", "direct", "Link: direct")
 	flag.StringVar(&cfg.transport, "transport", "datachannel", "Transport: datachannel")
 	flag.StringVar(&cfg.carrier, "carrier", "", "Carrier: telemost, jazz, wb_stream")
 	flag.StringVar(&cfg.roomID, "id", "", "Room ID")
@@ -132,6 +134,7 @@ func loadNames(dataDir string) error {
 func toSessionConfig(cfg config) session.Config {
 	return session.Config{
 		Mode:           cfg.mode,
+		Link:           cfg.link,
 		Transport:      cfg.transport,
 		Carrier:        firstNonEmpty(cfg.carrier, cfg.provider),
 		RoomID:         cfg.roomID,

internal/app/session/session.go

@@ -27,6 +27,8 @@ var (
 	ErrCarrierRequired = errors.New("carrier required (use -carrier telemost or -carrier jazz)")
 	// ErrUnsupportedCarrier indicates that carrier is not registered.
 	ErrUnsupportedCarrier = errors.New("unsupported carrier")
+	// ErrUnsupportedLink indicates that link is not registered.
+	ErrUnsupportedLink = errors.New("unsupported link")
 	// ErrUnsupportedTransport indicates that transport is not registered.
 	ErrUnsupportedTransport = errors.New("unsupported transport")
 )
@@ -34,6 +36,7 @@ var (
 // Config holds runtime session settings.
 type Config struct {
 	Mode           string
+	Link           string
 	Transport      string
 	Carrier        string
 	RoomID         string
@@ -75,11 +78,22 @@ func Validate(cfg Config) error {
 		}
 	}
 
+	availableLinks := link.Available()
+	validLink := false
+	for _, l := range availableLinks {
+		if cfg.Link == l {
+			validLink = true
+			break
+		}
+	}
+
 	switch {
 	case cfg.Carrier == "":
 		return ErrCarrierRequired
 	case !validCarrier:
 		return fmt.Errorf("%w: %s (available: %v)", ErrUnsupportedCarrier, cfg.Carrier, availableCarriers)
+	case !validLink:
+		return fmt.Errorf("%w: %s (available: %v)", ErrUnsupportedLink, cfg.Link, availableLinks)
 	case !validTransport:
 		return fmt.Errorf("%w: %s (available: %v)", ErrUnsupportedTransport, cfg.Transport, availableTransports)
 	case cfg.RoomID == "" && cfg.Carrier != "jazz":
@@ -99,6 +113,7 @@ func Run(ctx context.Context, cfg Config) error {
 	case "srv":
 		return server.Run(
 			ctx,
+			cfg.Link,
 			cfg.Transport,
 			cfg.Carrier,
 			roomURL,
@@ -110,6 +125,7 @@ func Run(ctx context.Context, cfg Config) error {
 	case "cnc":
 		return client.Run(
 			ctx,
+			cfg.Link,
 			cfg.Transport,
 			cfg.Carrier,
 			roomURL,

internal/client/client.go

@@ -58,6 +58,7 @@ type Client struct {
 // Run starts the client with the specified parameters.
 func Run(
 	ctx context.Context,
+	linkName,
 	transportName,
 	providerName,
 	roomURL,
@@ -67,12 +68,13 @@ func Run(
 	socksUser string,
 	socksPass string,
 ) error {
-	return RunWithReady(ctx, transportName, providerName, roomURL, keyHex, localAddr, dnsServer, socksUser, socksPass, nil)
+	return RunWithReady(ctx, linkName, transportName, providerName, roomURL, keyHex, localAddr, dnsServer, socksUser, socksPass, nil)
 }
 
 // RunWithReady is like Run but accepts a callback that is called when the client is ready.
 func RunWithReady(
 	ctx context.Context,
+	linkName,
 	transportName,
 	providerName,
 	roomURL,
@@ -109,7 +111,7 @@ func RunWithReady(
 
 	const peerCount = 1
 	for i := range peerCount {
-		if err := c.addTransport(runCtx, transportName, providerName, roomURL, i, cancel, dnsServer, "", 0); err != nil {
+		if err := c.addTransport(runCtx, linkName, transportName, providerName, roomURL, i, cancel, dnsServer, "", 0); err != nil {
 			return fmt.Errorf("addTransport failed: %w", err)
 		}
 	}
@@ -187,6 +189,7 @@ func (c *Client) setupMux() {
 
 func (c *Client) addTransport(
 	ctx context.Context,
+	linkName,
 	transportName,
 	providerName,
 	roomURL string,
@@ -196,7 +199,7 @@ func (c *Client) addTransport(
 	socksProxyAddr string,
 	socksProxyPort int,
 ) error {
-	ln, err := link.New(ctx, "direct", link.Config{
+	ln, err := link.New(ctx, linkName, link.Config{
 		Transport: transportName,
 		Carrier:   providerName,
 		RoomURL:   roomURL,

internal/link/link.go

@@ -53,3 +53,12 @@ func New(ctx context.Context, name string, cfg Config) (Link, error) {
 	}
 	return factory(ctx, cfg)
 }
+
+// Available returns a list of registered link names.
+func Available() []string {
+	names := make([]string, 0, len(registry))
+	for name := range registry {
+		names = append(names, name)
+	}
+	return names
+}

internal/server/server.go

@@ -68,6 +68,7 @@ type ConnectRequest struct {
 // Run starts the server with the specified parameters.
 func Run(
 	ctx context.Context,
+	linkName,
 	transportName,
 	providerName,
 	roomURL,
@@ -103,7 +104,7 @@ func Run(
 
 	const peerCount = 1
 	for i := range peerCount {
-		if err := s.addTransport(runCtx, transportName, providerName, roomURL, i, cancel); err != nil {
+		if err := s.addTransport(runCtx, linkName, transportName, providerName, roomURL, i, cancel); err != nil {
 			return fmt.Errorf("addTransport failed: %w", err)
 		}
 	}
@@ -187,13 +188,14 @@ func (s *Server) setupMux() {
 
 func (s *Server) addTransport(
 	ctx context.Context,
+	linkName,
 	transportName,
 	providerName,
 	roomURL string,
 	peerID int,
 	cancel context.CancelFunc,
 ) error {
-	ln, err := link.New(ctx, "direct", link.Config{
+	ln, err := link.New(ctx, linkName, link.Config{
 		Transport: transportName,
 		Carrier:   providerName,
 		RoomURL:   roomURL,

mobile/mobile.go

@@ -109,6 +109,7 @@ func Start(roomID, keyHex string, socksPort int, socksUser, socksPass string) er
 
 		err := client.RunWithReady(
 			ctx,
+			"direct",
 			"datachannel",
 			"telemost",
 			roomURL,