Snapshot Parser (Client)

Parses SERVER_SNAPSHOT packets into structured data (SnapshotParseResult) that can be applied by the replication system.

Input

• Raw std::vector<uint8_t> buffers dequeued from the network message handler.
• Expected layout: [Header][Payload][CRC32] with PacketType::ServerToClient and MessageType::Snapshot.

Validation

• Header: magic, protocol version, packet type = ServerToClient, message type = Snapshot.
• Sizes: payload size matches buffer length (including CRC).
• CRC: recomputed over header + payload and compared to the transmitted CRC32.
• If any check fails, parsing returns nullopt.

Payload layout

• entityCount (2 bytes)
• For each entity:
• entityId (4 bytes)
• updateMask (2 bytes)
• Optional fields if bits are set:
  • bit 0: entityType (1 byte)
  • bit 1: posX (float)
  • bit 2: posY (float)
  • bit 3: velX (float)
  • bit 4: velY (float)
  • bit 5: health (int16)
  • bit 6: statusEffects (1 byte)
  • bit 7: orientation (float)
  • bit 8: dead (1 byte, 0 = alive, 1 = dead)

Output

• SnapshotParseResult containing:
• PacketHeader header
• std::vector<SnapshotEntity> entities
  • Each SnapshotEntity holds entityId, updateMask, and optional values for the fields indicated by the mask.

Usage

• Invoked by NetworkMessageHandler when a snapshot packet is dequeued.
• The parsed result is pushed to a thread-safe queue for the replication system.

Tests

• tests/client/network/SnapshotParserTests.cpp covers full parse, multiple entities, missing data, wrong packet/message type, CRC mismatch, and size validation.