LiteSpeed QUIC (lsquic) Implementation

Development Status

This plugin is currently in development phase.

Plugin Type: Service (Implementation Under Test)

Verified Source Location: plugins/services/iut/quic/lsquic/

Purpose and Overview

The lsquic plugin provides integration with LiteSpeed's QUIC implementation, a high-performance C library developed by LiteSpeed Technologies. lsquic is a production-grade implementation optimized for server workloads and high-throughput scenarios, widely used in commercial web servers and CDN infrastructure.

The lsquic implementation plugin is designed for:

• High-performance QUIC server evaluation
• Production-grade HTTP/3 testing scenarios
• CDN and edge server compatibility validation
• Load testing and throughput benchmarking
• Commercial deployment scenario simulation

Requirements and Dependencies

The plugin requires:

• lsquic Library: LiteSpeed QUIC C library
• BoringSSL/OpenSSL: TLS 1.3 cryptographic backend
• libevent: Event loop library for network I/O
• Build Tools: C compiler, make, cmake

Docker-based deployment includes pre-built binaries and dependencies.

Configuration Options

Version Configuration

Parameter	Type	Default	Description
version	String	""	lsquic library version to use
commit	String	""	Specific commit hash for builds
dependencies	List	[]	Additional library dependencies

Server Configuration

Parameter	Type	Default	Description
role	String	"server"	Service role: "server" or "client"
port	Integer	4433	QUIC port number
interface	String	"0.0.0.0"	Network interface to bind
cert_file	String	""	Path to X.509 certificate
key_file	String	""	Path to private key
ca_file	String	""	Path to certificate authority file

Protocol Configuration

Parameter	Type	Default	Description
alpn_protocols	List	["h3"]	ALPN protocol list
versions	List	["h3-29","h3"]	Supported QUIC versions
max_connections	Integer	1000	Maximum concurrent connections
max_streams_per_conn	Integer	100	Maximum streams per connection
idle_timeout	Integer	60	Connection idle timeout (seconds)

Performance Tuning

Parameter	Type	Default	Description
max_packet_size	Integer	1452	Maximum UDP packet size
initial_max_data	Integer	10485760	Initial connection flow control limit
initial_max_stream_data	Integer	1048576	Initial stream flow control limit
cc_algo	String	"cubic"	Congestion control algorithm
pacing	Boolean	true	Enable packet pacing

Advanced Options

Parameter	Type	Default	Description
keylog_file	String	""	TLS key log file for debugging
qlog_dir	String	""	Directory for qlog trace files
log_level	String	"info"	Logging verbosity level
delayed_acks	Boolean	true	Enable delayed ACK optimization
ecn	Boolean	false	Enable Explicit Congestion Notification

Usage Examples

High-Performance Server

services:
  iut:
    type: "lsquic"
    role: "server"
    port: 443
    interface: "0.0.0.0"
    cert_file: "/certs/server.crt"
    key_file: "/certs/server.key"
    max_connections: 10000
    max_streams_per_conn: 1000
    cc_algo: "cubic"
    pacing: true
    alpn_protocols: ["h3", "h3-29"]

Load Testing Configuration

services:
  iut:
    type: "lsquic"
    role: "server"
    port: 4433
    max_connections: 50000
    initial_max_data: 104857600  # 100MB
    initial_max_stream_data: 10485760  # 10MB
    delayed_acks: true
    ecn: true
    log_level: "warn"  # Reduced logging for performance

Client Testing Setup

services:
  iut:
    type: "lsquic"
    role: "client"
    server_host: "test.example.com"
    port: 4433
    alpn_protocols: ["h3"]
    versions: ["h3-29", "h3"]
    max_streams_per_conn: 10
    keylog_file: "/debug/lsquic-keys.log"

Development and Debugging

services:
  iut:
    type: "lsquic"
    role: "server"
    port: 4433
    log_level: "debug"
    qlog_dir: "/logs/qlog"
    keylog_file: "/logs/keylog.txt"
    delayed_acks: false  # Disable for deterministic timing

Features

High-Performance Architecture

• Zero-Copy Operations: Optimized buffer management
• Event-Driven I/O: Efficient libevent integration
• Connection Pooling: Scalable connection management
• CPU Optimization: SIMD and architecture-specific optimizations

QUIC Protocol Features

• RFC 9000 Compliance: Full QUIC transport implementation
• Version Negotiation: Multi-version QUIC support
• Connection Migration: Transparent endpoint changes
• 0-RTT Resumption: Zero Round Trip Time connections
• Congestion Control: Multiple algorithms (cubic, bbr, adaptive)

HTTP/3 Support

• HTTP/3 Semantics: Complete HTTP over QUIC
• QPACK Compression: Header compression with dynamic tables
• Server Push: HTTP/3 server-initiated streams
• Priority Handling: Stream prioritization and dependencies

Production Features

• Load Balancing: Connection distribution capabilities
• Rate Limiting: Built-in connection and bandwidth limits
• Health Monitoring: Connection state and performance metrics
• Graceful Degradation: Fallback mechanisms for errors

Performance Characteristics

Strengths

• High Throughput: Optimized for server workloads
• Low Latency: Minimal processing overhead
• Scalability: Handles thousands of concurrent connections
• Memory Efficiency: Optimized memory allocation patterns

Optimization Features

• Adaptive Pacing: Dynamic packet transmission timing
• Smart Retransmission: Efficient loss recovery algorithms
• Flow Control: Advanced window management
• CPU Affinity: NUMA-aware processing

Testing and Validation

Performance Testing

• Throughput benchmarking under high connection loads
• Latency measurement across different network conditions
• Memory usage profiling during sustained operations
• CPU utilization analysis during peak loads

Conformance Testing

• QUIC protocol compliance verification
• HTTP/3 interoperability validation
• TLS 1.3 security compliance testing
• Version negotiation correctness verification

Stress Testing

• Connection exhaustion scenarios
• Memory pressure testing
• Network congestion simulation
• Error injection and recovery validation

Production Deployment

CDN Integration

• Edge server deployment scenarios
• Multi-region load balancing
• Cache invalidation over QUIC
• Real-time content delivery

Web Server Integration

• LiteSpeed Web Server compatibility
• Apache/Nginx proxy scenarios
• SSL termination configurations
• Virtual host management

Monitoring and Metrics

services:
  iut:
    type: "lsquic"
    role: "server"
    # Enable comprehensive logging
    qlog_dir: "/var/log/lsquic/qlog"
    log_level: "info"
    # Performance monitoring
    stats_interval: 30
    connection_metrics: true

Development and Extension

Custom Configuration

• Protocol parameter tuning for specific use cases
• Application-specific ALPN protocol registration
• Custom congestion control algorithm integration
• Extended logging and metrics collection

Integration Patterns

// Custom event handling
struct event_handler {
    void (*on_connection)(lsquic_conn_t *);
    void (*on_stream)(lsquic_stream_t *);
    void (*on_close)(lsquic_conn_t *);
};

// Performance monitoring hooks
struct perf_monitor {
    void (*on_packet_sent)(size_t bytes);
    void (*on_packet_received)(size_t bytes);
    void (*on_rtt_update)(lsquic_time_t rtt);
};

Extension Guidelines

• Use official lsquic APIs for custom functionality
• Implement proper error handling for network conditions
• Configure appropriate buffer sizes for target workloads
• Monitor memory usage in long-running deployments

Troubleshooting

Common Issues

Connection Drops

• Check firewall UDP port configuration
• Verify certificate validity and chains
• Monitor connection timeout settings
• Review congestion control behavior

Performance Bottlenecks

• Profile CPU usage during peak loads
• Check memory allocation patterns
• Monitor network interface utilization
• Tune buffer sizes for workload

TLS/Security Issues

• Verify certificate trust chains
• Check ALPN protocol negotiation
• Review TLS 1.3 configuration
• Validate key exchange mechanisms

Debug Configuration

services:
  iut:
    type: "lsquic"
    log_level: "debug"
    qlog_dir: "/debug/qlogs"
    keylog_file: "/debug/keys.log"
    # Disable optimizations for debugging
    pacing: false
    delayed_acks: false

Performance Profiling

# CPU profiling
perf record -g ./lsquic_server
perf report

# Memory profiling
valgrind --tool=massif ./lsquic_server

# Network analysis
tcpdump -i any -w lsquic_traffic.pcap udp port 4433

Related Documentation

• QUIC Protocol Overview: General QUIC implementation guide
• Performance Tuning: Optimization strategies
• Production Deployment: Deployment best practices

References

• lsquic GitHub Repository
• LiteSpeed Technologies
• QUIC RFC 9000
• HTTP/3 RFC 9114
• QPACK RFC 9204