/// <summary>
/// The capture thread
/// </summary>
protected virtual void CaptureThread()
{
if (!Opened)
{
throw new DeviceNotReadyException("Capture called before PcapDevice.Open()");
}
var usePoll = (this is LibPcapLiveDevice) &&
isLibPcap && MonoUnixFound;
// unix specific code
int captureFileDescriptor = 0;
if (usePoll)
{
// retrieve the file descriptor of the adapter for use with poll()
captureFileDescriptor = LibPcapSafeNativeMethods.pcap_fileno(PcapHandle);
if (captureFileDescriptor == -1)
{
SendCaptureStoppedEvent(CaptureStoppedEventStatus.ErrorWhileCapturing);
return;
}
}
LibPcapSafeNativeMethods.pcap_handler Callback = new LibPcapSafeNativeMethods.pcap_handler(PacketHandler);
// unix specific code
#if UseMonoUnixNativeDirectly
Pollfd[] pollFds = new Pollfd[1];
#else
System.Array pollFds = null;
object[] PollParameters = null;
#endif
// Timeout chosen to allow the capture thread to loop frequently enough
// to enable it to properly exit when the user requests it to but
// infrequently enough to cause any noticable performance overhead
int millisecondTimeout = 500;
if (usePoll)
{
#if UseMonoUnixNativeDirectly
pollFds[0].fd = captureFileDescriptor;
pollFds[0].events = PollEvents.POLLPRI | Mono.Unix.Native.PollEvents.POLLIN;
#else
FieldInfo field;
pollFds = Array.CreateInstance(PollfdType, 1);
// create a PollFd struct instance
var pollFd = Activator.CreateInstance(PollfdType);
// set the descriptor field
field = PollfdType.GetField("fd");
field.SetValue(pollFd, captureFileDescriptor);
// set the events field
short eventValue = (short)(POLLIN | POLLPRI); // mask the two together
field = PollfdType.GetField("events");
field.SetValue(pollFd, eventValue);
// set the Pollfd entry
pollFds.SetValue(pollFd, 0);
// setup the parameters we will pass to the poll() method
PollParameters = new object[2];
PollParameters[0] = pollFds;
PollParameters[1] = millisecondTimeout;
#endif
}
while (!shouldCaptureThreadStop)
{
// unix specific code, we want to poll for packets
// otherwise if we call pcap_dispatch() the read() will block
// and won't resume until a packet arrives OR until a signal
// occurs
if (usePoll)
{
// block here
#if UseMonoUnixNativeDirectly
var result = Mono.Unix.Native.Syscall.poll(pollFds, millisecondTimeout);
#else
object o = SyscallType.InvokeMember("poll",
BindingFlags.InvokeMethod,
Type.DefaultBinder,
null,
PollParameters);
int result = (int)o;
#endif
// if we have no poll results, just loop
if (result <= 0)
{
continue;
}
// fall through here to the pcap_dispatch() call
}
int res = LibPcapSafeNativeMethods.pcap_dispatch(PcapHandle, m_pcapPacketCount, Callback, IntPtr.Zero);
// pcap_dispatch() returns the number of packets read or, a status value if the value
// is negative
if (res <= 0)
{
switch (res) // Check pcap loop status results and notify upstream.
{
case Pcap.LOOP_USER_TERMINATED: // User requsted loop termination with StopCapture()
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
case Pcap.LOOP_COUNT_EXHAUSTED: // m_pcapPacketCount exceeded (successful exit)
{
// NOTE: pcap_dispatch() returns 0 when a timeout occurrs so to prevent timeouts
// from causing premature exiting from the capture loop we only consider
// exhausted events to cause an escape from the loop when they are from
// offline devices, ie. files read from disk
if (this is CaptureFileReaderDevice)
{
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
}
break;
}
case Pcap.LOOP_EXIT_WITH_ERROR: // An error occurred whilst capturing.
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
default: // This can only be triggered by a bug in libpcap.
throw new PcapException("Unknown pcap_loop exit status.");
}
}
else // res > 0
{
// if we aren't capturing infinitely we need to account for
// the packets that we read
if (m_pcapPacketCount != Pcap.InfinitePacketCount)
{
// take away for the packets read
if (m_pcapPacketCount >= res)
{
m_pcapPacketCount -= res;
}
else
{
m_pcapPacketCount = 0;
}
// no more packets to capture, we are finished capturing
if (m_pcapPacketCount == 0)
{
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
}
}
}
}
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
}
/// <summary>
/// The capture thread
/// </summary>
protected virtual void CaptureThread(CancellationToken cancellationToken)
{
if (!Opened)
{
throw new DeviceNotReadyException("Capture called before PcapDevice.Open()");
}
var Callback = new LibPcapSafeNativeMethods.pcap_handler(PacketHandler);
Posix.Pollfd[] pollFds = null;
// unix specific code
if (UsePosixPoll)
{
// retrieve the file descriptor of the adapter for use with poll()
var captureFileDescriptor = LibPcapSafeNativeMethods.pcap_fileno(PcapHandle);
if (captureFileDescriptor == -1)
{
SendCaptureStoppedEvent(CaptureStoppedEventStatus.ErrorWhileCapturing);
return;
}
pollFds = new Posix.Pollfd[1];
pollFds[0].fd = captureFileDescriptor;
pollFds[0].events = Posix.PollEvents.POLLPRI | Posix.PollEvents.POLLIN;
}
while (!cancellationToken.IsCancellationRequested)
{
// unix specific code, we want to poll for packets
// otherwise if we call pcap_dispatch() the read() will block
// and won't resume until a packet arrives OR until a signal
// occurs
if (pollFds != null)
{
// Timeout chosen to allow the capture thread to loop frequently enough
// to enable it to properly exit when the user requests it to but
// infrequently enough to cause any noticable performance overhead
const int millisecondTimeout = 500;
// block here
var result = Posix.Poll(pollFds, (uint)pollFds.Length, millisecondTimeout);
// if we have no poll results, just loop
if (result <= 0)
{
continue;
}
// fall through here to the pcap_dispatch() call
}
int res = LibPcapSafeNativeMethods.pcap_dispatch(PcapHandle, m_pcapPacketCount, Callback, IntPtr.Zero);
// pcap_dispatch() returns the number of packets read or, a status value if the value
// is negative
if (res <= 0)
{
switch (res) // Check pcap loop status results and notify upstream.
{
case Pcap.LOOP_USER_TERMINATED: // User requsted loop termination with StopCapture()
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
case Pcap.LOOP_COUNT_EXHAUSTED: // m_pcapPacketCount exceeded (successful exit)
{
// NOTE: pcap_dispatch() returns 0 when a timeout occurrs so to prevent timeouts
// from causing premature exiting from the capture loop we only consider
// exhausted events to cause an escape from the loop when they are from
// offline devices, ie. files read from disk
if (this is CaptureFileReaderDevice)
{
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
}
break;
}
case Pcap.LOOP_EXIT_WITH_ERROR: // An error occurred whilst capturing.
SendCaptureStoppedEvent(CaptureStoppedEventStatus.ErrorWhileCapturing);
return;
default: // This can only be triggered by a bug in libpcap.
throw new PcapException("Unknown pcap_loop exit status.");
}
}
else // res > 0
{
// if we aren't capturing infinitely we need to account for
// the packets that we read
if (m_pcapPacketCount != Pcap.InfinitePacketCount)
{
// take away for the packets read
if (m_pcapPacketCount >= res)
{
m_pcapPacketCount -= res;
}
else
{
m_pcapPacketCount = 0;
}
// no more packets to capture, we are finished capturing
if (m_pcapPacketCount == 0)
{
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
return;
}
}
}
}
SendCaptureStoppedEvent(CaptureStoppedEventStatus.CompletedWithoutError);
}