t.Errorf("socks5 proxy second read: got %v, want %v", buf[:3], want)
			return
		}
		var ipLen int
		switch buf[3] {
		case 1:
			ipLen = net.IPv4len
		case 4:
			ipLen = net.IPv6len
		default:
			t.Errorf("socks5 proxy second read: unexpected address type %v", buf[4])
			return
		}
		if _, err := io.ReadFull(s, buf[4:ipLen+6]); err != nil {