# Packet Logging System

## Overview

Comprehensive packet logging system for debugging the MapleStory protocol, matching the Java version's logging format.

## Features

- **Direction Indicators**: `[client]` for incoming packets, `[loopback]` for outgoing packets
- **Opcode Names**: Human-readable packet names (e.g., `CP_CheckPassword`, `LP_ServerList`)
- **Opcode Values**: Both decimal and hexadecimal (e.g., `2 / 0x02`)
- **Raw Hex Data**: Space-separated hex bytes
- **ASCII Text**: Printable characters with dots for non-printable
- **Context Information**: IP address, server type, packet size

## Configuration

Enable/disable packet logging in `config/config.exs`:

```elixir
config :odinsea, :features,
  log_packet: true  # Set to false to disable
```

## Example Output

```
[client] [CP_PermissionRequest] 1 / 0x01
[Data] 01 00 07 70 00 04 00
[Text] ...p...
[Context] IP=127.0.0.1 Server=login Size=7 bytes

[loopback] [RSA_KEY] 32 / 0x20
[Data] 20 00
[Text]  .
[Context] IP=127.0.0.1 Server=login Size=2 bytes
```

## Implementation Details

### Files Added

- `lib/odinsea/net/packet_logger.ex` - Main packet logging module

### Files Modified

- `lib/odinsea/login/client.ex` - Added packet logging for incoming client packets
- `lib/odinsea/login/handler.ex` - Added packet logging for outgoing server packets
- `lib/odinsea/net/processor.ex` - Fixed handler function name mismatches

### Key Functions

#### `PacketLogger.log_client_packet/3`
Logs incoming packets from the client with opcode, data, and context.

#### `PacketLogger.log_server_packet/3`
Logs outgoing packets to the client with opcode, data, and context.

#### `PacketLogger.log_raw_packet/4`
Logs raw packets (e.g., hello handshake) that don't follow the standard opcode format.

## Opcode Name Resolution

The logger includes comprehensive opcode name mappings for:

- **Client Opcodes** (CP_*): Login, authentication, character management, gameplay, etc.
- **Server Opcodes** (LP_*): Responses, server lists, character data, game state, etc.

Unknown opcodes are displayed as `UNKNOWN`.

## Usage Tips

1. **Enable during development**: Keep `log_packet: true` to debug connection issues
2. **Disable in production**: Set `log_packet: false` to reduce log noise and improve performance
3. **Compare with Java logs**: Use this to verify protocol compatibility with the Java server
4. **Debug handshake issues**: Check that HELLO packet is sent before CP_PermissionRequest

## Debugging Login Issues

The login sequence should look like this:

1. **[loopback] HELLO** - Server sends handshake with IVs
2. **[client] CP_PermissionRequest** - Client sends version check
3. **[loopback] RSA_KEY / LOGIN_AUTH** - Server sends RSA key and login background
4. **[client] CP_CheckPassword** - Client sends login credentials
5. **[loopback] LOGIN_STATUS** - Server sends authentication result

If packets are missing or out of order, check:
- Network connectivity
- Client version compatibility (v342)
- Opcode mappings in `opcodes.ex`
- Handler routing in `processor.ex`