Function dialFunc

internal/exit/exit.go:252–274

dialFunc returns a dial function. When proxyAddr is non-empty it routes all outbound connections through the SOCKS5 proxy at that address; otherwise it falls back to net.DialTimeout.

(proxyAddr string)

// outbound connections through the SOCKS5 proxy at that address; otherwise it
// falls back to net.DialTimeout.
func dialFunc(proxyAddr string) func(network, address string, timeout time.Duration) (net.Conn, error) {
	if proxyAddr == "" {
		return net.DialTimeout
	}
	forward := &net.Dialer{Timeout: 15 * time.Second}
	d, err := proxy.SOCKS5("tcp", proxyAddr, nil, forward)
	if err != nil {
		// proxy.SOCKS5 only errors on bad auth config; with nil auth this never fires.
		log.Printf("[exit] upstream_proxy: failed to build SOCKS5 dialer: %v — falling back to direct", err)
		return net.DialTimeout
	}
	cd, ok := d.(proxy.ContextDialer)
	if !ok {
		return func(_, address string, _ time.Duration) (net.Conn, error) {
			return d.Dial("tcp", address)
		}
	}
	return func(_, address string, timeout time.Duration) (net.Conn, error) {
		ctx, cancel := context.WithTimeout(context.Background(), timeout)
		defer cancel()
		return cd.DialContext(ctx, "tcp", address)
	}
}

// ListenAndServe blocks. It binds an HTTP listener on cfg.ListenAddr with one
// route, POST /tunnel, that handles batched encrypted frames.