package net

import (
	"context"
	"errors"
	"internal/poll"
	"internal/syscall/unix"
	"sync"
	"syscall"
)

var (
	mptcpOnce      sync.Once
	mptcpAvailable bool
	hasSOLMPTCP    bool
)

// These constants aren't in the syscall package, which is frozen
const (
	_IPPROTO_MPTCP = 0x106
	_SOL_MPTCP     = 0x11c
	_MPTCP_INFO    = 0x1
)

func supportsMultipathTCP() bool {

		ch <- err
		return
	}

	if !mptcp {
		ch <- errors.New("incoming connection is not with MPTCP")
		return
	}

	// Also check the method for the older kernels if not tested before
	if hasSOLMPTCP && !isUsingMPTCPProto(tcp.fd) {
		ch <- errors.New("incoming connection is not an MPTCP proto")
		return
	}
}

func dialerMPTCP(t *testing.T, addr string, envVar bool) {
	d := &Dialer{}

	if envVar {