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package arping
import (
"fmt"
"net"
"syscall"
"time"
)
type LinuxSocket struct {
sock int
toSockaddr syscall.SockaddrLinklayer
}
func initialize(iface net.Interface) (s *LinuxSocket, err error) {
s = &LinuxSocket{}
s.toSockaddr = syscall.SockaddrLinklayer{Ifindex: iface.Index}
// 1544 = htons(ETH_P_ARP)
const proto = 1544
s.sock, err = syscall.Socket(syscall.AF_PACKET, syscall.SOCK_RAW, proto)
return s, err
}
func (s *LinuxSocket) send(request arpDatagram) (time.Time, error) {
return time.Now(), syscall.Sendto(s.sock, request.MarshalWithEthernetHeader(), 0, &s.toSockaddr)
}
func (s *LinuxSocket) receive() (arpDatagram, time.Time, error) {
buffer := make([]byte, 128)
socketTimeout := timeout.Nanoseconds() * 2
t := syscall.NsecToTimeval(socketTimeout)
syscall.SetsockoptTimeval(s.sock, syscall.SOL_SOCKET, syscall.SO_RCVTIMEO, &t)
n, _, err := syscall.Recvfrom(s.sock, buffer, 0)
if err != nil {
return arpDatagram{}, time.Now(), err
}
if n <= 14 {
// amount of bytes read by socket is less than an ethernet header. clearly not what we look for
return arpDatagram{}, time.Now(), fmt.Errorf("buffer with invalid length")
}
// skip 14 bytes ethernet header
return parseArpDatagram(buffer[14:n]), time.Now(), nil
}
func (s *LinuxSocket) deinitialize() error {
return syscall.Close(s.sock)
}
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