// SetBufferSize should only be called on a Pcap that was obtained through
// Create. If the buffer size is too small then Activate will fail with a
// generic PCAP_ERROR.
func (p *Pcap) SetBufferSize(bufferSize int32) error {
// If you try to set a negative buffer size
// you are going to have a bad time.
if bufferSize < 0 {
return fmt.Errorf("negative buffer size")
}
res := int32(C.pcap_set_buffer_size(p.cptr, C.int(bufferSize)))
if res < 0 {
return fmt.Errorf("%s(errnum=%d)", Statustostr(res), res)
}
return nil
}
func main() {
var errbuf = (*C.char)(C.malloc(C.PCAP_ERRBUF_SIZE))
defer C.free(unsafe.Pointer(errbuf))
var source = C.CString("any")
defer C.free(unsafe.Pointer(source))
pcap_handle := C.pcap_create(source, errbuf)
if pcap_handle == nil {
panic("pcap_handle")
}
C.pcap_set_buffer_size(pcap_handle, 2*1024*1024)
C.pcap_set_promisc(pcap_handle, 1)
C.pcap_set_snaplen(pcap_handle, 512) // more than enough to recognize a WOL packet
C.pcap_setdirection(pcap_handle, C.PCAP_D_IN)
if C.pcap_activate(pcap_handle) != 0 {
panic(C.GoString(C.pcap_geterr(pcap_handle)))
}
var bpf_program C.struct_bpf_program
if C.pcap_compile(pcap_handle, &bpf_program, pcap_filter, 0, 0) != 0 {
panic(C.GoString(C.pcap_geterr(pcap_handle)))
}
if C.pcap_setfilter(pcap_handle, &bpf_program) != 0 {
panic(C.GoString(C.pcap_geterr(pcap_handle)))
}
for {
var pkt_header *C.struct_pcap_pkthdr
var pkt_data *C.u_char
if C.pcap_next_ex(pcap_handle, &pkt_header, &pkt_data) < 0 {
panic(C.GoString(C.pcap_geterr(pcap_handle)))
}
if pkt_data == nil {
continue
}
data := make([]byte, pkt_header.caplen)
copy(data, (*(*[10000000]byte)(unsafe.Pointer(pkt_data)))[0:])
from_mac, to_mac := checkwol(data)
if from_mac != "" {
fmt.Printf("%v: %v sends WOL to %v\n", time.Now(), from_mac, to_mac)
}
}
}
// SetBufferSize sets the buffer size (in bytes) of the handle.
func (p *InactiveHandle) SetBufferSize(bufferSize int) error {
if status := C.pcap_set_buffer_size(p.cptr, C.int(bufferSize)); status < 0 {
return statusError(status)
}
return nil
}
// Set buffer size (units in bytes) on activated handle.
func (p *Pcap) SetBufferSize(sz int32) error {
if C.pcap_set_buffer_size(p.cptr, C.int(sz)) != 0 {
return p.Geterror()
}
return nil
}