package dialer import ( "net" "syscall" "golang.org/x/sys/unix" ) type controlFn = func(network, address string, c syscall.RawConn) error func bindControl(ifaceName string, chain controlFn) controlFn { return func(network, address string, c syscall.RawConn) (err error) { defer func() { if err == nil && chain != nil { err = chain(network, address, c) } }() ipStr, _, err := net.SplitHostPort(address) if err == nil { ip := net.ParseIP(ipStr) if ip != nil && !ip.IsGlobalUnicast() { return } } return c.Control(func(fd uintptr) { unix.BindToDevice(int(fd), ifaceName) }) } } func bindIfaceToDialer(ifaceName string, dialer *net.Dialer, _ string, _ net.IP) error { dialer.Control = bindControl(ifaceName, dialer.Control) return nil } func bindIfaceToListenConfig(ifaceName string, lc *net.ListenConfig, _, address string) (string, error) { lc.Control = bindControl(ifaceName, lc.Control) return address, nil }