xjasonlyu/tun2socks

package dialer

import (
    "net"
    "syscall"

    "golang.org/x/sys/unix"
)

func setSocketOptions(network, address string, c syscall.RawConn, opts *Options) (err error) {
    if opts == nil || !isTCPSocket(network) && !isUDPSocket(network) {
        return
    }

    var innerErr error
    err = c.Control(func(fd uintptr) {
        host, _, _ := net.SplitHostPort(address)
        if ip := net.ParseIP(host); ip != nil && !ip.IsGlobalUnicast() {
            return
        }

        if opts.InterfaceName == "" && opts.InterfaceIndex != 0 {
            if iface, err := net.InterfaceByIndex(opts.InterfaceIndex); err == nil {
                opts.InterfaceName = iface.Name
            }
        }

        if opts.InterfaceName != "" {
            if innerErr = unix.BindToDevice(int(fd), opts.InterfaceName); innerErr != nil {
                return
            }
        }
        if opts.RoutingMark != 0 {
            if innerErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, opts.RoutingMark); innerErr != nil {
                return
            }
        }
    })

    if innerErr != nil {
        err = innerErr
    }
    return
}