Method createX11Session

agent/agentssh/x11.go:226–264

createX11Session creates an X11 forwarding session.

(ctx context.Context, sshSession ssh.Session)

// createX11Session creates an X11 forwarding session.
func (x *x11Forwarder) createX11Session(ctx context.Context, sshSession ssh.Session) (*x11Session, error) {
	var (
		ln      net.Listener
		display int
		err     error
	)
	// retry listener creation after evictions. Limit to 10 retries to prevent pathological cases looping forever.
	const maxRetries = 10
	for try := range maxRetries {
		ln, display, err = x.createX11Listener(ctx)
		if err == nil {
			break
		}
		if try == maxRetries-1 {
			return nil, xerrors.New("max retries exceeded while creating X11 session")
		}
		x.logger.Warn(ctx, "failed to create X11 listener; will evict an X11 forwarding session",
			slog.F("num_current_sessions", x.numSessions()),
			slog.Error(err))
		x.evictLeastRecentlyUsedSession()
	}
	x.mu.Lock()
	defer x.mu.Unlock()
	if x.closing {
		closeErr := ln.Close()
		if closeErr != nil {
			x.logger.Error(ctx, "error closing X11 listener", slog.Error(closeErr))
		}
		return nil, xerrors.New("server is closing")
	}
	x11Sess := &x11Session{
		session:  sshSession,
		display:  display,
		listener: ln,
		usedAt:   time.Now(),
	}
	x.sessions[x11Sess] = struct{}{}
	return x11Sess, nil
}

func (x *x11Forwarder) numSessions() int {
	x.mu.Lock()