feat(agent,pkg): add configuration to tunnel listener and yamux server

Author: henrybarreto

agent/agent.go

@@ -631,7 +631,7 @@ func (a *Agent) Listen(ctx context.Context) error {
 
 			a.listening <- true
 
-			if err := a.tunnel.Listen(conn); err != nil {
+			if err := a.tunnel.Listen(conn, &tunnel.DefaultConfig); err != nil {
 				logger.WithError(err).Error("Tunnel listener exited with error")
 			}
 

agent/pkg/tunnel/tunnel.go

@@ -37,15 +37,66 @@ func (t *Tunnel) Handle(protocol string, handler Handler) {
 // ErrTunnelDisconnect is returned when the tunnel connection is closed.
 var ErrTunnelDisconnect = errors.New("tunnel disconnected")
 
-func (t *Tunnel) Listen(conn net.Conn) error {
+type Config struct {
+	// AcceptBacklog is used to limit how many streams may be
+	// waiting an accept.
+	AcceptBacklog int `json:"accept_backlog"`
+
+	// EnableKeepalive is used to do a period keep alive
+	// messages using a ping.
+	EnableKeepAlive bool `json:"enable_keep_alive"`
+
+	// KeepAliveInterval is how often to perform the keep alive
+	KeepAliveInterval time.Duration `json:"keep_alive_interval"`
+
+	// ConnectionWriteTimeout is meant to be a "safety valve" timeout after
+	// we which will suspect a problem with the underlying connection and
+	// close it. This is only applied to writes, where's there's generally
+	// an expectation that things will move along quickly.
+	ConnectionWriteTimeout time.Duration `json:"connection_write_timeout"`
+
+	// MaxStreamWindowSize is used to control the maximum
+	// window size that we allow for a stream.
+	MaxStreamWindowSize uint32 `json:"max_stream_window_size"`
+
+	// StreamOpenTimeout is the maximum amount of time that a stream will
+	// be allowed to remain in pending state while waiting for an ack from the peer.
+	// Once the timeout is reached the session will be gracefully closed.
+	// A zero value disables the StreamOpenTimeout allowing unbounded
+	// blocking on OpenStream calls.
+	StreamOpenTimeout time.Duration `json:"stream_open_timeout"`
+
+	// StreamCloseTimeout is the maximum time that a stream will allowed to
+	// be in a half-closed state when `Close` is called before forcibly
+	// closing the connection. Forcibly closed connections will empty the
+	// receive buffer, drop any future packets received for that stream,
+	// and send a RST to the remote side.
+	StreamCloseTimeout time.Duration `json:"stream_close_timeout"`
+}
+
+var DefaultConfig = Config{
+	AcceptBacklog:          256,
+	EnableKeepAlive:        true,
+	KeepAliveInterval:      35 * time.Second,
+	ConnectionWriteTimeout: 15 * time.Second,
+	MaxStreamWindowSize:    256 * 1024,
+	StreamCloseTimeout:     5 * time.Minute,
+	StreamOpenTimeout:      75 * time.Second,
+}
+
+func (t *Tunnel) Listen(conn net.Conn, cfg *Config) error {
+	if cfg == nil {
+		cfg = &DefaultConfig
+	}
+
 	session, err := yamux.Server(conn, &yamux.Config{
-		AcceptBacklog:          256,
-		EnableKeepAlive:        true,
-		KeepAliveInterval:      35 * time.Second,
-		ConnectionWriteTimeout: 15 * time.Second,
-		MaxStreamWindowSize:    256 * 1024,
-		StreamCloseTimeout:     5 * time.Minute,
-		StreamOpenTimeout:      75 * time.Second,
+		AcceptBacklog:          cfg.AcceptBacklog,
+		EnableKeepAlive:        cfg.EnableKeepAlive,
+		KeepAliveInterval:      cfg.KeepAliveInterval,
+		ConnectionWriteTimeout: cfg.ConnectionWriteTimeout,
+		MaxStreamWindowSize:    cfg.MaxStreamWindowSize,
+		StreamCloseTimeout:     cfg.StreamCloseTimeout,
+		StreamOpenTimeout:      cfg.StreamOpenTimeout,
 		LogOutput:              os.Stderr,
 	})
 	if err != nil {