// NewTPacket returns a new TPacket object for reading packets off the wire.
// Its behavior may be modified by passing in any/all of afpacket.Opt* to this
// function.
// If this function succeeds, the user should be sure to Close the returned
// TPacket when finished with it.
func NewTPacket(opts ...interface{}) (h *TPacket, err error) {
h = &TPacket{}
if h.opts, err = parseOptions(opts...); err != nil {
return nil, err
}
fd, err := C.socket(C.AF_PACKET, C.int(h.opts.socktype), C.int(C.htons(C.ETH_P_ALL)))
if err != nil {
return nil, err
}
h.fd = fd
if h.opts.iface != "" {
if err = h.bindToInterface(h.opts.iface); err != nil {
goto errlbl
}
}
if err = h.setRequestedTPacketVersion(); err != nil {
goto errlbl
}
if err = h.setUpRing(); err != nil {
goto errlbl
}
// Clear stat counter from socket
if err = h.InitSocketStats(); err != nil {
goto errlbl
}
runtime.SetFinalizer(h, (*TPacket).Close)
return h, nil
errlbl:
h.Close()
return nil, err
}
// bindToInterface binds the TPacket socket to a particular named interface.
func (h *TPacket) bindToInterface(ifaceName string) error {
iface, err := net.InterfaceByName(ifaceName)
if err != nil {
return fmt.Errorf("InterfaceByName: %v", err)
}
var ll C.struct_sockaddr_ll
ll.sll_family = C.AF_PACKET
ll.sll_protocol = C.__be16(C.htons(C.ETH_P_ALL))
ll.sll_ifindex = C.int(iface.Index)
if _, err := C.bind(h.fd, (*C.struct_sockaddr)(unsafe.Pointer(&ll)), C.socklen_t(unsafe.Sizeof(ll))); err != nil {
return fmt.Errorf("bindToInterface: %v", err)
}
return nil
}
