Fix #2109: Recognize LLC payload in SLL2. (#2111)

* Add LLC parsing to SLL2.

* Replace hardcoded protocol type value.

* Update docs.

* Add small test for LLC parse.

* Fix typo.

* Change enum to constexpr value.

* Cleanup unused includes.

Author: Dimi1010

Packet++/src/Sll2Layer.cpp

@@ -9,10 +9,17 @@
 #include "VlanLayer.h"
 #include "PPPoELayer.h"
 #include "MplsLayer.h"
+#include "LLCLayer.h"
 #include "EndianPortable.h"
 
 namespace pcpp
 {
+	namespace
+	{
+		/// @brief Exclusive Sll2 value indicating 802.2 LLC header payload.
+		constexpr uint16_t Sll2ProtoTypeLLC = 0x0004;
+	}  // namespace
+
 	Sll2Layer::Sll2Layer(uint32_t interfaceIndex, uint16_t ARPHRDType, uint8_t packetType)
 	{
 		const size_t headerLen = sizeof(sll2_header);
@@ -103,6 +110,11 @@ namespace pcpp
 			constructNextLayer<MplsLayer>(payload, payloadLen);
 			break;
 		}
+		case Sll2ProtoTypeLLC:
+		{
+			tryConstructNextLayerWithFallback<LLCLayer, PayloadLayer>(payload, payloadLen);
+			break;
+		}
 		default:
 		{
 			constructNextLayer<PayloadLayer>(payload, payloadLen);
@@ -131,6 +143,9 @@ namespace pcpp
 		case VLAN:
 			hdr->protocol_type = htobe16(PCPP_ETHERTYPE_VLAN);
 			break;
+		case LLC:
+			hdr->protocol_type = htobe16(Sll2ProtoTypeLLC);
+			break;
 		default:
 			return;
 		}

Tests/Packet++Test/PacketExamples/Sll2PacketLLC.dat

@@ -0,0 +1 @@
+000400000000000300010206e01cfcd3b1e10000424203000002023e80004c5e0c3ec6dd00004e388000e01cfcd3b1df80020300140002000f000020202020202020

Tests/Packet++Test/PacketExamples/Sll2PacketLLC.pcap

@@ -140,6 +140,7 @@ PTF_TEST_CASE(NullLoopbackTest);
 
 // Implemented in Sll2Tests.cpp
 PTF_TEST_CASE(Sll2PacketParsingTest);
+PTF_TEST_CASE(Sll2ParseLLCTest);
 PTF_TEST_CASE(Sll2PacketCreationTest);
 
 // Implemented in NflogTests.cpp

Tests/Packet++Test/TestDefinition.h

@@ -42,6 +42,17 @@ PTF_TEST_CASE(Sll2PacketParsingTest)
 	PTF_ASSERT_EQUAL(macAddrRef, sll2Layer->getLinkLayerAsMacAddress());
 }  // Sll2PacketParsingTest
 
+PTF_TEST_CASE(Sll2ParseLLCTest)
+{
+	pcpp_tests::utils::PacketFactory ssl2Factory(pcpp::LINKTYPE_LINUX_SLL2);
+	auto rawPacket1 = createPacketFromHexResource("PacketExamples/Sll2PacketLLC.dat", ssl2Factory);
+
+	pcpp::Packet sll2Packet(rawPacket1.get());
+
+	PTF_ASSERT_TRUE(sll2Packet.isPacketOfType(pcpp::SLL2));
+	PTF_ASSERT_TRUE(sll2Packet.isPacketOfType(pcpp::LLC));
+}
+
 PTF_TEST_CASE(Sll2PacketCreationTest)
 {
 	pcpp::Sll2Layer sll2Layer(20, 1, 4);

Tests/Packet++Test/Tests/Sll2Tests.cpp

@@ -265,6 +265,7 @@ int main(int argc, char* argv[])
 	PTF_RUN_TEST(NullLoopbackTest, "null_loopback");
 
 	PTF_RUN_TEST(Sll2PacketParsingTest, "sll2");
+	PTF_RUN_TEST(Sll2ParseLLCTest, "sll2");
 	PTF_RUN_TEST(Sll2PacketCreationTest, "sll2");
 
 	PTF_RUN_TEST(NflogPacketParsingTest, "nflog");