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QuicD

Introduction to QuicD

QuicD is a high-performance QUIC server implementation written in Rust, designed to enable developers to build modern internet applications on a solid, scalable foundation. Whether you’re serving HTTP/3 content, streaming low-latency media, or building custom protocols, QuicD provides the performance and flexibility you need.

What is QuicD?

Section titled “What is QuicD?”

QuicD is an open-source QUIC server that combines cutting-edge Linux technologies with Rust’s safety guarantees to deliver exceptional performance. It’s built on three key pillars:

  • Performance: Leverages io_uring for zero-copy I/O and eBPF for intelligent connection routing
  • Extensibility: Pluggable application layer lets you implement any QUIC-based protocol
  • Safety: Written in Rust, ensuring memory safety without sacrificing performance

At its core, QuicD orchestrates network I/O, QUIC protocol handling, and application logic in a carefully designed architecture that eliminates contention and maximizes throughput.

What is QUIC?

Section titled “What is QUIC?”

QUIC (Quick UDP Internet Connections) is a modern transport protocol that addresses the limitations of traditional TCP/TLS stacks:

  • UDP-based: Built on UDP for flexibility and reduced kernel overhead
  • Always encrypted: TLS 1.3 is built into the protocol, not layered on top
  • Multiplexed: Multiple independent streams share a single connection without head-of-line blocking
  • Connection migration: Connections survive network changes (Wi-Fi to cellular)
  • 0-RTT: Resume connections instantly with zero round-trip time

QuicD implements QUIC v1 (RFC 9000) via the battle-tested Cloudflare Quiche library, ensuring compliance with the latest standards.

Use Cases

Section titled “Use Cases”

QuicD excels at building applications that demand low latency, high throughput, or both:

HTTP/3 Web Serving

Section titled “HTTP/3 Web Serving”

Serve modern web applications with HTTP/3 support built-in. QuicD includes a complete HTTP/3 implementation (RFC 9114) with QPACK header compression, ready to handle production traffic.

// HTTP/3 is registered by default
let registry = AppRegistry::new()
    .register("h3", Arc::new(H3Factory::new(YourHandler)));

Low-Latency Media Streaming

Section titled “Low-Latency Media Streaming”

Build Media over QUIC (MOQ) applications for live video, audio, or real-time communication. QUIC’s datagram support enables ultra-low-latency delivery with graceful degradation.

Custom QUIC Protocols

Section titled “Custom QUIC Protocols”

Implement domain-specific protocols for gaming, IoT, DNS over QUIC, or research. QuicD’s QuicAppFactory trait makes it straightforward to add new protocols without modifying the core server.

Real-Time Communications

Section titled “Real-Time Communications”

Take advantage of QUIC’s connection migration and 0-RTT features to build robust real-time applications that gracefully handle network changes.

Why Choose QuicD?

Section titled “Why Choose QuicD?”

Uncompromising Performance

Section titled “Uncompromising Performance”

QuicD is built for speed from the ground up:

  • io_uring: Zero-copy network I/O eliminates syscall overhead
  • eBPF routing: Intelligent connection affinity ensures packets reach the right worker thread
  • Zero-contention architecture: Native worker threads operate independently with no locks in the hot path
  • CPU affinity: Workers pinned to specific cores for optimal cache locality
  • Pre-allocated buffers: Eliminates allocation overhead in packet processing

Real-world performance: 100,000+ concurrent connections per worker, 10+ Gbps throughput (hardware-dependent).

True Flexibility

Section titled “True Flexibility”

QuicD is designed for extensibility:

  • Pluggable application layer: Implement QuicAppFactory to add new protocols
  • Zero-copy interfaces: Applications integrate via efficient channel-based APIs
  • Multiple protocols: Run HTTP/3, MOQ, and custom protocols on a single server
  • Configurable: Tune every aspect from buffer pool sizes to flow control parameters

Rust Safety Guarantees

Section titled “Rust Safety Guarantees”

Built in Rust, QuicD provides memory safety without garbage collection overhead. The borrow checker ensures thread-safe concurrent access, eliminating entire classes of security vulnerabilities.

Architecture at a Glance

Section titled “Architecture at a Glance”

QuicD’s architecture separates concerns for optimal performance:

graph LR
    A[UDP Packets] --> B[io_uring]
    B --> C[Worker Threads]
    C --> D[QUIC Manager]
    D --> E[Connection]
    E --> F[App Task]
    F --> G[Your Protocol Logic]
  • Native worker threads: Handle all network I/O and QUIC protocol processing
  • Tokio async tasks: Run application logic (one task per connection)
  • Zero-copy channels: Efficient communication between layers
  • eBPF routing: Ensures connection affinity for cache efficiency

Learn more in the Architecture guide.

Getting Started

Section titled “Getting Started”

Ready to build with QuicD? Here’s how to get started:

  1. Install QuicD: Build from source or use cargo install
  2. Configure your server: Set up workers, buffers, and QUIC parameters
  3. Run HTTP/3: Start serving HTTP/3 traffic immediately
  4. Build custom apps: Implement your own QUIC-based protocols

Community and Support

Section titled “Community and Support”

QuicD is an open-source project welcoming contributions:

Next Steps

Section titled “Next Steps”

QuicD is designed and built for developers who demand both performance and flexibility. Let’s build the next generation of internet applications together.