rustvncserver

A pure Rust VNC (Virtual Network Computing) server library with complete RFB protocol support.

Features

Protocol Support

• ✅ RFB 3.8 - Full RFC 6143 compliance
• ✅ 11 Encodings - All major VNC encodings supported
• ✅ All Pixel Formats - 8/16/24/32-bit color depths
• ✅ Authentication - VNC authentication protocol
• ✅ Reverse Connections - Connect to listening viewers
• ✅ Repeater Support - UltraVNC Mode-2 repeaters

Supported Encodings

*Untested encodings: ZlibHex, CoRRE, and ZYWRLE are fully implemented and RFC 6143 compliant but cannot be tested with noVNC (most common test client) because noVNC doesn't support them. All three have been code-reviewed and verified against the RFC 6143 specification. Use the widely-supported alternatives: Zlib (instead of ZlibHex), Hextile (instead of CoRRE), and ZRLE (instead of ZYWRLE).

Tight Encoding (All 5 Production Modes)

1. Solid Fill - 1 color (5 bytes for entire rectangle)
2. Mono Rect - 2 colors, 1-bit bitmap
3. Indexed Palette - 3-16 colors with indices
4. Full-Color Zlib - Lossless RGB24 compression
5. JPEG - Lossy compression via TurboJPEG (optional feature)

Implementation

• Pure Rust - Memory safe, no unsafe code in core logic
• Async I/O - Built on Tokio for concurrent client handling
• Zero-copy - Arc-based framebuffer sharing
• Persistent Compression Streams - Better compression ratios
• Thread-safe - Safe concurrent access to framebuffer

Installation

Add to your Cargo.toml:

[dependencies]
rustvncserver = "0.1"
tokio = { version = "1", features = ["rt-multi-thread", "macros"] }

Optional Features

[dependencies]
rustvncserver = { version = "0.1", features = ["turbojpeg"] }

Features:

• turbojpeg - Enable TurboJPEG for hardware-accelerated JPEG compression (requires libjpeg-turbo)

Quick Start

use rustvncserver::VncServer;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create VNC server
    let server = VncServer::new(1920, 1080);

    // Optional: Set password
    server.set_password(Some("secret".to_string()));

    // Start listening
    server.listen(5900).await?;

    Ok(())
}

Examples

Simple Server

use rustvncserver::VncServer;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let server = VncServer::new(800, 600);
    server.set_password(Some("test".to_string()));

    // Create test pattern
    let mut pixels = vec![0u8; 800 * 600 * 4]; // RGBA32
    for y in 0..600 {
        for x in 0..800 {
            let offset = (y * 800 + x) * 4;
            pixels[offset] = (x * 255 / 800) as u8;     // R
            pixels[offset + 1] = (y * 255 / 600) as u8; // G
            pixels[offset + 2] = 128;                   // B
            pixels[offset + 3] = 255;                   // A
        }
    }

    server.update_framebuffer(&pixels, 0, 0, 800, 600);
    server.listen(5900).await?;

    Ok(())
}

Run examples:

cargo run --example simple_server
cargo run --example headless_server

Handling Events

use rustvncserver::{VncServer, ServerEvent};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let server = VncServer::new(1920, 1080);

    // Get event receiver
    let mut events = server.events();

    // Handle events in background
    tokio::spawn(async move {
        while let Ok(event) = events.recv().await {
            match event {
                ServerEvent::ClientConnected { id, address } => {
                    println!("Client {} connected from {}", id, address);
                }
                ServerEvent::PointerEvent { x, y, button_mask, .. } => {
                    println!("Pointer: ({}, {}) buttons={}", x, y, button_mask);
                }
                ServerEvent::KeyEvent { key, pressed, .. } => {
                    println!("Key: {} {}", key, if pressed { "pressed" } else { "released" });
                }
                _ => {}
            }
        }
    });

    server.listen(5900).await?;
    Ok(())
}

Reverse Connection

// Connect to a listening viewer
server.connect_reverse("192.168.1.100", 5500).await?;

CopyRect Optimization

// Efficiently copy screen regions (scrolling, window dragging)
server.schedule_copy_rect(0, 100, 1920, 980, 0, -100); // Scroll up
server.do_copy_rect(); // Execute

API Documentation

VncServer

impl VncServer {
    /// Create new server with given dimensions
    pub fn new(width: u16, height: u16) -> Self;

    /// Start listening on TCP port
    pub async fn listen(&self, port: u16) -> Result<()>;

    /// Connect to listening viewer (reverse connection)
    pub async fn connect_reverse(&self, host: &str, port: u16) -> Result<()>;

    /// Connect to repeater
    pub async fn connect_repeater(&self, host: &str, port: u16, id: &str) -> Result<()>;

    /// Update framebuffer region
    pub fn update_framebuffer(&self, data: &[u8], x: u16, y: u16, width: u16, height: u16);

    /// Resize framebuffer
    pub fn resize_framebuffer(&self, width: u16, height: u16);

    /// Schedule CopyRect operation
    pub fn schedule_copy_rect(&self, x: u16, y: u16, width: u16, height: u16, dx: i16, dy: i16);

    /// Execute scheduled CopyRect operations
    pub fn do_copy_rect(&self);

    /// Send clipboard text to all clients
    pub fn send_clipboard(&self, text: &str);

    /// Set authentication password
    pub fn set_password(&self, password: Option<String>);

    /// Get event receiver
    pub fn events(&self) -> mpsc::Receiver<ServerEvent>;

    /// Stop server
    pub fn stop(&self);
}

ServerEvent

pub enum ServerEvent {
    ClientConnected { id: usize, address: SocketAddr },
    ClientDisconnected { id: usize },
    PointerEvent { client_id: usize, x: u16, y: u16, button_mask: u8 },
    KeyEvent { client_id: usize, key: u32, pressed: bool },
    ClipboardReceived { client_id: usize, text: String },
}

Performance

Encoding Speed (1920x1080 frame)

Memory Usage

Platform Support

• ✅ Linux (x86_64, ARM64)
• ✅ macOS (x86_64, Apple Silicon)
• ✅ Windows (x86_64)
• ✅ Android (via JNI wrapper - see RustVNC)

Why Rust?

This pure Rust implementation provides several advantages over traditional C implementations:

Advantages:

• ✅ Memory safety (no buffer overflows, use-after-free)
• ✅ Thread safety (no data races)
• ✅ Modern async I/O (better scalability)
• ✅ Smaller codebase (~3,500 vs ~20,000 lines)
• ✅ Better error handling
• ✅ Zero-copy framebuffer updates

Compatibility:

• ✅ Same protocols (RFC 6143)
• ✅ Same encodings (byte-for-byte identical wire format)
• ✅ Same features (authentication, reverse connections, repeater)
• ✅ Works with all VNC viewers (TightVNC, RealVNC, TigerVNC, noVNC, etc.)

Building

# Build library
cargo build --release

# Run tests
cargo test

# Run examples
cargo run --example simple_server

# Build with TurboJPEG support (requires libjpeg-turbo)
cargo build --release --features turbojpeg

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Run cargo fmt and cargo clippy
6. Submit a pull request

License

Apache-2.0 - See LICENSE file for details.

This library implements the VNC protocol as specified in RFC 6143, which is a public specification. The ZYWRLE algorithm is used under a BSD-style license from Hitachi Systems & Services, Ltd. All Rust dependencies use MIT or dual MIT/Apache-2.0 licenses.

Credits

• Author: Dustin McAfee
• Protocol: Implements RFC 6143 (RFB Protocol Specification)
• Used in: RustVNC - VNC server for Android

See Also

• RFC 6143 - RFB Protocol Specification
• TECHNICAL.md - Detailed technical documentation
• NOTICE - Third-party licenses and attributions

Pure Rust VNC Server - Memory Safe, Protocol Compliant, Production Ready 🦀