C2: Add Ethernet message support

include/icsneo/communication/message/ethernetmessage.h

@@ -4,63 +4,89 @@
 #ifdef __cplusplus
 
 #include "icsneo/communication/message/message.h"
+#include <array>
 #include <string>
 #include <vector>
 #include <sstream>
 #include <iomanip>
 #include <cstring>
+#include <optional>
 
 namespace icsneo {
 
-struct MACAddress {
-	uint8_t data[6];
-
-	std::string toString() const {
-		std::stringstream ss;
-		for(size_t i = 0; i < 6; i++) {
-			ss << std::hex << std::setw(2) << std::setfill('0') << (int)data[i];
-			if(i != 5)
-				ss << ':';
-		}
-		return ss.str();
-	}
-
-	friend std::ostream& operator<<(std::ostream& os, const MACAddress& mac) {
-		os << mac.toString();
-		return os;
-	}
-};
+using MACAddress = std::array<uint8_t, 6>;
 
 class EthernetMessage : public Frame {
 public:
 	// Standard Ethernet fields
-	bool preemptionEnabled = false;
-	uint8_t preemptionFlags = 0;
+	// Frame Check Sequence
 	std::optional<uint32_t> fcs;
 	bool frameTooShort = false;
 	bool noPadding = false;
 	bool fcsVerified = false;
 	bool txAborted = false;
 	bool crcError = false;
-	bool isT1S = false;
-
 	
-	bool isT1SSymbol = false;
-	bool isT1SBurst = false;
-	bool txCollision = false;
-	bool isT1SWake = false;
-	uint8_t t1sNodeId = 0;
-	uint8_t t1sBurstCount = 0;
-	uint8_t t1sSymbolType = 0;
+	// T1S-specific fields
+	struct T1S {
+		T1S() {}
 
-	// Accessors
-	const MACAddress& getDestinationMAC() const { return *(const MACAddress*)(data.data() + 0); }
-	const MACAddress& getSourceMAC() const { return *(const MACAddress*)(data.data() + 6); }
-	uint16_t getEtherType() const { return (data[12] << 8) | data[13]; }
+		bool isSymbol = false;
+		bool isBurst = false;
+		bool txCollision = false;
+		bool isWake = false;
+		uint8_t nodeId = 0;
+		uint8_t burstCount = 0;
+		uint8_t symbolType = 0;
+	};
+	std::optional<T1S> t1s;
+
+	// TSN-specific fields
+	// If we expand TSN we should probably do something similar to what we did above with T1S.
+	// IEEE 802.1Qbu frame preemption
+	std::optional<uint8_t> preemptionFlags;
+
+	// Helper functions to extract Destination MAC from the data payload
+	// returns std::nullopt if the data payload is not large enough
+	std::optional<MACAddress> getDestinationMAC() const { 
+		if(data.size() < 6) {
+			return std::nullopt;
+		}
+		MACAddress mac;
+		std::copy(data.begin(), data.begin() + 6, mac.begin());
+		return mac;
+	}
+
+	// Helper functions to extract Source MAC from the data payload
+	// returns std::nullopt if the data payload is not large enough
+	std::optional<MACAddress> getSourceMAC() const { 
+		if(data.size() < 12) {
+			return std::nullopt;
+		}
+		MACAddress mac;
+		std::copy(data.begin() + 6, data.begin() + 12, mac.begin());
+		return mac;
+	}
+
+	// Helper function to extract EtherType from the data payload
+	//
+	// EtherType is a two-octet field in an Ethernet frame (big-endian).
+	// It is used to indicate which protocol is encapsulated in the payload of the frame 
+	// and is used at the receiving end by the data link layer to determine how the payload is processed.
+	// For example, an EtherType of 0x0800 indicates that the payload is an IPv4 packet, while 0x86DD indicates an IPv6 packet.
+	// 
+	// returns std::nullopt if the data payload is not large enough
+	std::optional<uint16_t> getEtherType() const { 
+		if(data.size() < 14) {
+			return std::nullopt;
+		}
+		// EtherType is stored in a 2-byte network byte order (big-endian)
+		return static_cast<uint16_t>((uint16_t(data[12]) << 8) | uint16_t(data[13]));
+	}
 };
 
 }
 
 #endif // __cplusplus
 
-#endif
+#endif // __ETHERNETMESSAGE_H_