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
}
}
}
func (d *bpfDev) Read(to *ethernet.Frame) (err error) {
to.Resize(d.ifce.MTU)
for {
for d.p < d.n {
hdr := (*bpfHdr)(unsafe.Pointer(&d.readBuf[d.p]))
frameStart := d.p + int(hdr.hdrlen)
n := int(hdr.caplen)
*to = (*to)[:n]
copy(*to, d.readBuf[frameStart:frameStart+n])
d.p += bpfWordalign(int(hdr.hdrlen) + int(hdr.caplen))
if !equalMAC(to.Source(), d.ifce.HardwareAddr) && (d.filter == nil || d.filter(*to)) {
return
}
}
d.n, err = d.fd.Read(d.readBuf)
if err != nil {
return
}
d.p = 0
}
}
func TestReadFrame(t *testing.T) {
var (
ifce *net.Interface
err error
d Dev
)
if ifce, err = net.InterfaceByName(*dev); err != nil {
t.Fatalf("getting interface error: %v", err)
}
d, err = NewDev(ifce, nil)
if err != nil {
t.Fatal(err)
}
var to ethernet.Frame
for i := 0; i < 16; i++ {
err = d.Read(&to)
t.Logf("got frame: from %v to %v (ethertype %v): % x\n", to.Source(), to.Destination(), to.Ethertype(), to.Payload())
if err != nil {
t.Fatal(err)
}
}
err = d.Close()
if err != nil {
t.Fatal(err)
}
for i := 0; i < 1024; i++ {
err = d.Read(&to)
if err != nil {
break
}
}
if err == nil {
t.Fatal("closed Dev can still read")
}
}