xjasonlyu/tun2socks

package dialer

import (
    "context"
    "net"
    "syscall"

    "go.uber.org/atomic"
)

var (
    DefaultInterfaceName  = atomic.NewString("")
    DefaultInterfaceIndex = atomic.NewInt32(0)
    DefaultRoutingMark    = atomic.NewInt32(0)
)

type Options struct {
    // InterfaceName is the name of interface/device to bind.
    // If a socket is bound to an interface, only packets received
    // from that particular interface are processed by the socket.
    InterfaceName string

    // InterfaceIndex is the index of interface/device to bind.
    // It is almost the same as InterfaceName except it uses the
    // index of the interface instead of the name.
    InterfaceIndex int

    // RoutingMark is the mark for each packet sent through this
    // socket. Changing the mark can be used for mark-based routing
    // without netfilter or for packet filtering.
    RoutingMark int
}

func DialContext(ctx context.Context, network, address string) (net.Conn, error) {
    return DialContextWithOptions(ctx, network, address, &Options{
        InterfaceName:  DefaultInterfaceName.Load(),
        InterfaceIndex: int(DefaultInterfaceIndex.Load()),
        RoutingMark:    int(DefaultRoutingMark.Load()),
    })
}

func DialContextWithOptions(ctx context.Context, network, address string, opts *Options) (net.Conn, error) {
    d := &net.Dialer{
        Control: func(network, address string, c syscall.RawConn) error {
            return setSocketOptions(network, address, c, opts)
        },
    }
    return d.DialContext(ctx, network, address)
}

func ListenPacket(network, address string) (net.PacketConn, error) {
    return ListenPacketWithOptions(network, address, &Options{
        InterfaceName:  DefaultInterfaceName.Load(),
        InterfaceIndex: int(DefaultInterfaceIndex.Load()),
        RoutingMark:    int(DefaultRoutingMark.Load()),
    })
}

func ListenPacketWithOptions(network, address string, opts *Options) (net.PacketConn, error) {
    lc := &net.ListenConfig{
        Control: func(network, address string, c syscall.RawConn) error {
            return setSocketOptions(network, address, c, opts)
        },
    }
    return lc.ListenPacket(context.Background(), network, address)
}