feat: add NLPacket protocol implementation for Overte domain communication

src/NLPacketCodec.hpp

@@ -0,0 +1,91 @@
+// NLPacketCodec.hpp
+// Minimal NLPacket protocol implementation for Overte domain communication
+// Based on Overte's NLPacket.h specification
+
+#pragma once
+
+#include <cstdint>
+#include <vector>
+#include <cstring>
+
+namespace Overte {
+
+// Packet types from Overte protocol
+enum class PacketType : uint8_t {
+    Unknown = 0,
+    Ping = 1,
+    PingReply = 2,
+    DomainList = 3,
+    DomainListRequest = 4,
+    DomainConnectionDenied = 6,
+    DomainServerRequireDTLS = 7,
+    DomainConnectRequest = 8,
+    DomainServerPathQuery = 9,
+    DomainServerPathResponse = 10,
+    DomainServerAddedNode = 11,
+    DomainServerConnectionToken = 12,
+    DomainSettingsRequest = 13,
+    DomainSettings = 14,
+    // ... many more packet types
+    EntityAdd = 0x41,
+    EntityEdit = 0x42,
+    EntityErase = 0x43,
+    EntityQuery = 0x44,
+    EntityData = 0x45,
+};
+
+using PacketVersion = uint8_t;
+using LocalID = uint16_t;
+using SequenceNumber = uint32_t;
+
+// NLPacket structure (minimal implementation)
+class NLPacket {
+public:
+    // Packet header components
+    struct Header {
+        uint32_t sequenceAndFlags;  // Sequence number (29 bits) + flags (3 bits)
+        PacketType type;
+        PacketVersion version;
+        LocalID sourceID;  // Only for sourced packets
+    };
+    
+    static constexpr LocalID NULL_LOCAL_ID = 0;
+    static constexpr size_t BASE_HEADER_SIZE = sizeof(uint32_t) + sizeof(PacketType) + sizeof(PacketVersion);
+    static constexpr size_t SOURCED_HEADER_SIZE = BASE_HEADER_SIZE + sizeof(LocalID);
+    
+    NLPacket(PacketType type, PacketVersion version = 0, bool isReliable = false);
+    
+    // Write data to packet payload
+    void write(const void* data, size_t size);
+    void writeUInt8(uint8_t value);
+    void writeUInt16(uint16_t value);
+    void writeUInt32(uint32_t value);
+    void writeUInt64(uint64_t value);
+    void writeString(const std::string& str, bool nullTerminated = true);
+    
+    // Get packet data for sending
+    const std::vector<uint8_t>& getData() const { return m_data; }
+    size_t getSize() const { return m_data.size(); }
+    
+    // Parse received packet
+    static bool parseHeader(const uint8_t* data, size_t size, Header& header);
+    static PacketType getType(const uint8_t* data, size_t size);
+    
+    void setSequenceNumber(SequenceNumber seq);
+    void setSourceID(LocalID id);
+    
+private:
+    void writeHeader();
+    
+    PacketType m_type;
+    PacketVersion m_version;
+    SequenceNumber m_sequenceNumber{0};
+    LocalID m_sourceID{NULL_LOCAL_ID};
+    bool m_isReliable;
+    bool m_isSourced{false};
+    
+    std::vector<uint8_t> m_data;
+    size_t m_headerSize;
+};
+
+} // namespace Overte