func (pc *packetSock) ReadFrom() ([]byte, net.IP, error) {
pkt := make([]byte, maxIPHdrLen+udpHdrLen+MaxDHCPLen)
n, _, err := unix.Recvfrom(pc.fd, pkt, 0)
if err != nil {
return nil, nil, err
}
// IP hdr len
ihl := int(pkt[0]&0x0F) * 4
// Source IP address
src := net.IP(pkt[12:16])
return pkt[ihl+udpHdrLen : n], src, nil
}
func (d *afpacket) Read(to *ethernet.Frame) (err error) {
to.Resize(d.ifce.MTU)
for {
*to = (*to)[:cap(*to)]
var n int
n, _, err = unix.Recvfrom(d.fd, []byte(*to), 0)
if err != nil {
return
}
*to = (*to)[:n]
if !equalMAC(to.Source(), d.ifce.HardwareAddr) && (d.filter == nil || d.filter(*to)) {
return
}
}
}