// +build linux

/*
 * MinIO Cloud Storage, (C) 2020 MinIO, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package http

import (
	"context"
	"net"
	"syscall"
	"time"
)

const (
	// TCPFastOpenConnect sets the underlying socket to use
	// the TCP fast open connect. This feature is supported
	// since Linux 4.11.
	TCPFastOpenConnect = 30
)

// DialContext is a function to make custom Dial for internode communications
type DialContext func(ctx context.Context, network, address string) (net.Conn, error)

// NewCustomDialContext setups a custom dialer for internode communications
func NewCustomDialContext(dialTimeout, dialKeepAlive time.Duration) DialContext {
	return func(ctx context.Context, network, addr string) (net.Conn, error) {
		dialer := &net.Dialer{
			Timeout:   dialTimeout,
			KeepAlive: dialKeepAlive,
			Control: func(network, address string, c syscall.RawConn) error {
				return c.Control(func(fd uintptr) {
					// Enable TCP fast connect
					_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, TCPFastOpenConnect, 1)
				})
			},
		}
		return dialer.DialContext(ctx, network, addr)
	}
}