Fix crash with parseuntil when top layer is more than the chosen parseuntil OSI layer. (#1580)

* Fix crash with parseuntil when top layer is more than the chosen parseuntil OSI layer.

* fix format

Author: rndx21033

Packet++/src/Packet.cpp

@@ -84,9 +84,17 @@ namespace pcpp
 
 		if (curLayer != nullptr && curLayer->getOsiModelLayer() > parseUntilLayer)
 		{
-			m_LastLayer = curLayer->getPrevLayer();
-			delete curLayer;
-			m_LastLayer->m_NextLayer = nullptr;
+			// don't delete the first layer. If already past the target layer, treat the same as if the layer was found.
+			if (curLayer == m_FirstLayer)
+			{
+				curLayer->m_IsAllocatedInPacket = true;
+			}
+			else
+			{
+				m_LastLayer = curLayer->getPrevLayer();
+				delete curLayer;
+				m_LastLayer->m_NextLayer = nullptr;
+			}
 		}
 
 		if (m_LastLayer != nullptr && parseUntil == UnknownProtocol && parseUntilLayer == OsiModelLayerUnknown)

Tests/Packet++Test/TestDefinition.h

@@ -58,6 +58,7 @@ PTF_TEST_CASE(PacketTrailerTest);
 PTF_TEST_CASE(ResizeLayerTest);
 PTF_TEST_CASE(PrintPacketAndLayersTest);
 PTF_TEST_CASE(ProtocolFamilyMembershipTest);
+PTF_TEST_CASE(PacketParseLayerLimitTest);
 
 // Implemented in HttpTests.cpp
 PTF_TEST_CASE(HttpRequestParseMethodTest);

Tests/Packet++Test/Tests/PacketTests.cpp

@@ -1068,3 +1068,17 @@ PTF_TEST_CASE(ProtocolFamilyMembershipTest)
 	PTF_ASSERT_FALSE(httpLayer->isMemberOfProtocolFamily(pcpp::HTTPResponse));
 	PTF_ASSERT_FALSE(httpLayer->isMemberOfProtocolFamily(pcpp::IP));
 }
+
+PTF_TEST_CASE(PacketParseLayerLimitTest)
+{
+	timeval time;
+	gettimeofday(&time, nullptr);
+
+	READ_FILE_AND_CREATE_PACKET(0, "PacketExamples/TcpPacketWithOptions3.dat");
+	pcpp::Packet packet0(&rawPacket0, pcpp::OsiModelPhysicalLayer);
+	PTF_ASSERT_EQUAL(packet0.getLastLayer(), packet0.getFirstLayer());
+
+	READ_FILE_AND_CREATE_PACKET(1, "PacketExamples/TcpPacketWithOptions3.dat");
+	pcpp::Packet packet1(&rawPacket1, pcpp::OsiModelTransportLayer);
+	PTF_ASSERT_EQUAL(packet1.getLastLayer()->getOsiModelLayer(), pcpp::OsiModelTransportLayer);
+}

Tests/Packet++Test/main.cpp

@@ -161,6 +161,7 @@ int main(int argc, char* argv[])
 	PTF_RUN_TEST(ResizeLayerTest, "packet;resize");
 	PTF_RUN_TEST(PrintPacketAndLayersTest, "packet;print");
 	PTF_RUN_TEST(ProtocolFamilyMembershipTest, "packet");
+	PTF_RUN_TEST(PacketParseLayerLimitTest, "packet");
 
 	PTF_RUN_TEST(HttpRequestParseMethodTest, "http");
 	PTF_RUN_TEST(HttpRequestLayerParsingTest, "http");