Remove magic identifiers from Ethernet analyzer.

scripts/base/packet-protocols/ethernet/main.zeek

@@ -1,4 +1,4 @@
-module LL_ETHERNET;
+module PacketAnalyzer::Ethernet;
 
 const DLT_EN10MB : count = 1;
 
@@ -15,3 +15,7 @@ redef PacketAnalyzer::config_map += {
 	#PacketAnalyzer::ConfigEntry($parent=PacketAnalyzer::ANALYZER_ETHERNET, $identifier=0x8864, $analyzer=PacketAnalyzer::ANALYZER_PPPOE),
 	PacketAnalyzer::ConfigEntry($parent=PacketAnalyzer::ANALYZER_ETHERNET, $analyzer=PacketAnalyzer::ANALYZER_DEFAULTANALYZER)
 };
+
+const snap_analyzer: PacketAnalyzer::Tag &redef;
+const novell_raw_analyzer: PacketAnalyzer::Tag &redef;
+const llc_analyzer: PacketAnalyzer::Tag &redef;

src/packet_analysis/Manager.cc

@@ -92,6 +92,49 @@ void Manager::DumpDebug()
 #endif
 	}
 
+AnalyzerPtr Manager::GetAnalyzer(EnumVal *val)
+	{
+	auto analyzer_comp = Lookup(val);
+	if ( ! analyzer_comp )
+		return nullptr;
+
+	return GetAnalyzer(analyzer_comp->Name());
+	}
+
+AnalyzerPtr Manager::GetAnalyzer(const std::string& name)
+	{
+	auto analyzer_it = analyzers.find(name);
+	if ( analyzer_it == analyzers.end() )
+		return nullptr;
+
+	return analyzer_it->second;
+	}
+
+void Manager::ProcessPacket(Packet* packet)
+	{
+#ifdef DEBUG
+	static size_t counter = 0;
+	DBG_LOG(DBG_PACKET_ANALYSIS, "Analyzing packet %ld, ts=%.3f...", ++counter, packet->time);
+#endif
+	// Start packet analysis
+	const uint8_t* data = packet->data;
+
+	auto root_analyzer = root_dispatcher.Lookup(packet->link_type);
+	auto analyzer = root_analyzer ? root_analyzer : default_analyzer;
+	if ( !analyzer )
+		{
+		reporter->InternalWarning("No analyzer for link type %#x", packet->link_type);
+		return;
+		}
+
+	auto result = analyzer->Analyze(packet, data);
+	if (result == AnalyzerResult::Terminate)
+		CustomEncapsulationSkip(packet, data);
+
+	// Calculate header size after processing packet layers.
+	packet->hdr_size = static_cast<uint32_t>(data - packet->data);
+	}
+
 AnalyzerPtr Manager::InstantiateAnalyzer(const Tag& tag)
 	{
 	Component* c = Lookup(tag);
@@ -119,7 +162,7 @@ AnalyzerPtr Manager::InstantiateAnalyzer(const Tag& tag)
 	if ( tag != a->GetAnalyzerTag() )
 		{
 		reporter->InternalError("Mismatch of requested analyzer %s and instantiated analyzer %s. This usually means that the plugin author made a mistake.",
-		                        GetComponentName(tag).c_str(), GetComponentName(a->GetAnalyzerTag()).c_str());
+								GetComponentName(tag).c_str(), GetComponentName(a->GetAnalyzerTag()).c_str());
 		}
 
 	return a;
@@ -131,31 +174,6 @@ AnalyzerPtr Manager::InstantiateAnalyzer(const std::string& name)
 	return tag ? InstantiateAnalyzer(tag) : nullptr;
 	}
 
-void Manager::ProcessPacket(Packet* packet)
-	{
-#ifdef DEBUG
-	static size_t counter = 0;
-	DBG_LOG(DBG_PACKET_ANALYSIS, "Analyzing packet %ld, ts=%.3f...", ++counter, packet->time);
-#endif
-	// Start packet analysis
-	const uint8_t* data = packet->data;
-
-	auto root_analyzer = root_dispatcher.Lookup(packet->link_type);
-	auto analyzer = root_analyzer ? root_analyzer : default_analyzer;
-	if ( !analyzer )
-		{
-		reporter->InternalWarning("No analyzer for link type %#x", packet->link_type);
-		return;
-		}
-
-	auto result = analyzer->Analyze(packet, data);
-	if (result == AnalyzerResult::Terminate)
-		CustomEncapsulationSkip(packet, data);
-
-	// Calculate header size after processing packet layers.
-	packet->hdr_size = static_cast<uint32_t>(data - packet->data);
-	}
-
 void Manager::CustomEncapsulationSkip(Packet* packet, const uint8_t* data)
 	{
 	if ( zeek::detail::encap_hdr_size > 0 )

src/packet_analysis/Manager.h

@@ -44,26 +44,22 @@ public:
 	void DumpDebug(); // Called after zeek_init() events.
 
 	/**
-	 * Instantiates a new analyzer instance.
+	 * Looks up an analyzer instance.
 	 *
-	 * @param tag The analyzer's tag.
+	 * @param val The analyzer's tag value.
 	 *
-	 * @return The new analyzer instance. Returns
-	 * null if tag is invalid, the requested analyzer is disabled, or the
-	 * analyzer can't be instantiated.
+	 * @return The analyzer instance or nullptr if no instance is found.
 	 */
-	AnalyzerPtr InstantiateAnalyzer(const Tag& tag);
+	AnalyzerPtr GetAnalyzer(EnumVal *val);
 
 	/**
-	 * Instantiates a new analyzer.
+	 * Looks up an analyzer instance.
 	 *
 	 * @param name The name of the analyzer.
 	 *
-	 * @return The new analyzer instance. Returns
-	 * null if the name is not known or if the requested analyzer that is
-	 * disabled.
+	 * @return The analyzer instance or nullptr if no instance is found.
 	 */
-	AnalyzerPtr InstantiateAnalyzer(const std::string& name);
+	AnalyzerPtr GetAnalyzer(const std::string& name);
 
 	/**
 	 * Processes a packet by applying the configured packet analyzers.
@@ -73,6 +69,26 @@ public:
 	void ProcessPacket(Packet* packet);
 
 private:
+	/**
+	 * Instantiates a new analyzer instance.
+	 *
+	 * @param tag The analyzer's tag.
+	 *
+	 * @return The new analyzer instance. Returns null if tag is invalid, the
+	 * requested analyzer is disabled, or the analyzer can't be instantiated.
+	 */
+	AnalyzerPtr InstantiateAnalyzer(const Tag& tag);
+
+	/**
+	 * Instantiates a new analyzer.
+	 *
+	 * @param name The name of the analyzer.
+	 *
+	 * @return The new analyzer instance. Returns null if the name is not known
+	 * or if the requested analyzer that is disabled.
+	 */
+	AnalyzerPtr InstantiateAnalyzer(const std::string& name);
+
 	/**
 	 * Skips a fixed amount of packet data that is defined by encap_hdr_size.
 	 * It is assumed that an IP header follows.

src/packet_analysis/protocol/ethernet/Ethernet.cc

@@ -2,6 +2,7 @@
 
 #include "Ethernet.h"
 #include "NetVar.h"
+#include "Manager.h"
 
 using namespace zeek::packet_analysis::Ethernet;
 
@@ -10,6 +11,26 @@ EthernetAnalyzer::EthernetAnalyzer()
 	{
 	}
 
+void EthernetAnalyzer::Initialize()
+	{
+	SNAPAnalyzer = LoadAnalyzer("PacketAnalyzer::Ethernet::snap_analyzer");
+	NovellRawAnalyzer = LoadAnalyzer("PacketAnalyzer::Ethernet::novell_raw_analyzer");
+	LLCAnalyzer = LoadAnalyzer("PacketAnalyzer::Ethernet::llc_analyzer");
+	}
+
+zeek::packet_analysis::AnalyzerPtr EthernetAnalyzer::LoadAnalyzer(const std::string &name)
+	{
+	auto& analyzer = zeek::id::find(name);
+	if ( ! analyzer )
+		return nullptr;
+
+	auto& analyzer_val = analyzer->GetVal();
+	if ( ! analyzer_val )
+		return nullptr;
+
+	return packet_mgr->GetAnalyzer(analyzer_val->AsEnumVal());
+	}
+
 zeek::packet_analysis::AnalyzerResult EthernetAnalyzer::Analyze(Packet* packet, const uint8_t*& data)
 	{
 	auto end_of_data = packet->GetEndOfData();
@@ -59,22 +80,25 @@ zeek::packet_analysis::AnalyzerResult EthernetAnalyzer::Analyze(Packet* packet,
 			return AnalyzerResult::Failed;
 			}
 
-		// In the following we use undefined EtherTypes to signal uncommon
-		// frame types. This allows specialized analyzers to take over.
+		// Let specialized analyzers take over for non Ethernet II frames.
 		// Note that pdata remains at the start of the ethernet frame.
-		//TODO: Lookup the analyzers on startup
 
-		// IEEE 802.2 SNAP
+		AnalyzerPtr eth_analyzer = nullptr;
+
 		if ( data[14] == 0xAA && data[15] == 0xAA)
-			return AnalyzeInnerPacket(packet, data, 1502);
+			// IEEE 802.2 SNAP
+			eth_analyzer = SNAPAnalyzer;
+		else if ( data[14] == 0xFF && data[15] == 0xFF)
+			// Novell raw IEEE 802.3
+			eth_analyzer = NovellRawAnalyzer;
+		else
+			// IEEE 802.2 LLC
+			eth_analyzer = LLCAnalyzer;
 
-		// Novell raw IEEE 802.3
-		if ( data[14] == 0xFF && data[15] == 0xFF)
-			return AnalyzeInnerPacket(packet, data, 1503);
+		if ( eth_analyzer )
+			return eth_analyzer->Analyze(packet, data);
 
-
-		// IEEE 802.2 LLC
-		return AnalyzeInnerPacket(packet, data, 1501);
+		return AnalyzerResult::Terminate;
 		}
 
 	// Undefined (1500 < EtherType < 1536)

src/packet_analysis/protocol/ethernet/Ethernet.h

@@ -12,12 +12,20 @@ public:
 	EthernetAnalyzer();
 	~EthernetAnalyzer() override = default;
 
+	void Initialize() override;
 	AnalyzerResult Analyze(Packet* packet, const uint8_t*& data) override;
 
 	static zeek::packet_analysis::AnalyzerPtr Instantiate()
 		{
 		return std::make_shared<EthernetAnalyzer>();
 		}
+
+private:
+	AnalyzerPtr SNAPAnalyzer = nullptr;
+	AnalyzerPtr NovellRawAnalyzer = nullptr;
+	AnalyzerPtr LLCAnalyzer = nullptr;
+
+	AnalyzerPtr LoadAnalyzer(const std::string& name);
 };
 
 }