Added guard clause to stopCapture to prevent incomplete shutdown. (#1833)

* Added guard clause if `stopCapture` is called from the same thread that executes the callbacks.

* Added condition to skip throwing an error if stopCapture is called without a started capture.

Author: Dimi1010

Pcap++/header/PcapLiveDevice.h

@@ -499,6 +499,7 @@ namespace pcpp
 
 		/// Stop a currently running packet capture. This method terminates gracefully both packet capture thread and
 		/// periodic stats collection thread (both if exist)
+		/// @remarks This method should not be called from the onPacketArrives callback, as it will cause a deadlock.
 		void stopCapture();
 
 		/// Check if a capture thread is running

Pcap++/src/PcapLiveDevice.cpp

@@ -873,6 +873,11 @@ namespace pcpp
 		if (m_cbOnPacketArrivesBlockingMode != nullptr)
 			return;
 
+		if (m_CaptureThread.get_id() != std::thread::id{} && m_CaptureThread.get_id() == std::this_thread::get_id())
+		{
+			throw std::runtime_error("Cannot stop capture from the capture thread itself");
+		}
+
 		m_StopThread = true;
 		if (m_CaptureThreadStarted)
 		{