techircd/docs/CONNECTION_HANDLING.md

TechIRCd Connection Handling Improvements

Overview

TechIRCd now features robust connection handling designed to handle real-world network conditions, client behaviors, and edge cases gracefully.

Key Improvements

🛡️ Robust Client Connection Handling

1. Comprehensive Error Recovery

• Panic Recovery: All client handlers have panic recovery with detailed logging
• Graceful Cleanup: Proper resource cleanup even when connections fail
• Connection Validation: Validates connections and server state before processing

2. Smart Timeout Management

• Registration Timeout: 60 seconds for initial registration (configurable)
• Read Timeouts: 5 minutes for registered clients, 30 seconds during registration
• Progressive Timeouts: More lenient timeouts for new connections

3. Enhanced Message Processing

• Binary Data Detection: Detects and rejects non-text data
• Size Limits: Truncates oversized messages (512 bytes max)
• Empty Line Handling: Gracefully ignores empty lines
• Encoding Validation: Checks for valid IRC characters

4. Intelligent Flood Protection

• Registration Leniency: More generous limits during connection setup
• Sliding Window: Proper flood detection with time windows
• Configurable Limits: Respects server configuration settings

🔧 Server Connection Management

1. Connection Limits

• Max Client Enforcement: Rejects connections when server is full
• Resource Protection: Prevents server overload
• Graceful Rejection: Sends proper error message before closing

2. Accept Error Handling

• Temporary Error Recovery: Handles temporary network errors
• Retry Logic: Continues accepting after temporary failures
• Error Classification: Different handling for different error types

3. Client State Tracking

• Connection Counting: Real-time client count tracking
• State Validation: Ensures clients are properly initialized
• Resource Monitoring: Tracks and logs connection statistics

📊 Enhanced Logging and Debugging

1. Detailed Connection Logging

2025/09/03 19:02:44 New client connected from 46.24.193.29:60237 (total: 1)
2025/09/03 19:02:44 Starting robust client handler for 46.24.193.29:60237
2025/09/03 19:02:44 Client 46.24.193.29:60237: CAP LS 302
2025/09/03 19:02:44 Client 46.24.193.29:60237: NICK TestUser
2025/09/03 19:02:44 Client registration completed: TestUser (testuser) from 46.24.193.29:60237

2. Error Context

• Connection Source: Always logs client IP/port
• Error Details: Specific error messages for troubleshooting
• State Information: Logs registration status and timing

3. Performance Metrics

• Connection Duration: Tracks how long connections last
• Message Counts: Monitors message frequency
• Registration Time: Measures time to complete registration

🔒 Security Enhancements

1. Protocol Validation

• Command Validation: Ensures only valid IRC commands are processed
• Data Sanitization: Removes dangerous or malformed input
• Buffer Management: Prevents buffer overflow attacks

2. Connection Security

• Rate Limiting: Prevents rapid connection attempts
• Resource Limits: Protects against resource exhaustion
• Input Validation: Validates all client input before processing

🚀 Real-World Compatibility

1. IRC Client Support

• HexChat Compatible: Tested with popular IRC clients
• IRCv3 Support: Handles capability negotiation properly
• Standard Compliance: Follows RFC 2812 standards

2. Network Conditions

• Slow Connections: Handles high-latency connections
• Unstable Networks: Recovers from temporary network issues
• Mobile Clients: Optimized for mobile network conditions

3. Edge Cases

• Partial Messages: Handles incomplete message transmission
• Connection Drops: Graceful handling of sudden disconnections
• Server Restarts: Proper cleanup during server shutdown

Configuration Options

Timeout Settings

{
  "limits": {
    "registration_timeout": 60,
    "ping_timeout": 300,
    "flood_lines": 10,
    "flood_seconds": 60
  }
}

Connection Limits

{
  "limits": {
    "max_clients": 1000,
    "max_channels": 100
  }
}

Benefits

For Users

• ✅ Reliable Connections: Less likely to drop due to network issues
• ✅ Faster Registration: Optimized registration process
• ✅ Better Error Messages: Clear feedback when issues occur
• ✅ Mobile Friendly: Works well on mobile networks

For Administrators

• ✅ Detailed Logging: Easy troubleshooting with comprehensive logs
• ✅ Resource Protection: Server stays stable under load
• ✅ Security: Protection against malformed data and attacks
• ✅ Monitoring: Real-time connection statistics

For Developers

• ✅ Code Clarity: Well-structured connection handling code
• ✅ Error Recovery: Robust error handling prevents crashes
• ✅ Debugging: Extensive logging for issue resolution
• ✅ Maintainability: Clean separation of concerns

Testing Recommendations

Basic Connection Test

# Test with telnet
telnet your-server.com 6667

# Send IRC commands
NICK TestUser
USER testuser 0 * :Test User

HexChat Configuration

• Server: your-server.com
• Port: 6667 (or 6697 for SSL)
• SSL: Disabled (unless you have SSL configured)
• Character Set: UTF-8

Load Testing

• Test with multiple simultaneous connections
• Try rapid connect/disconnect cycles
• Test with slow network conditions

TechIRCd now provides enterprise-grade connection handling suitable for production IRC networks!