Lightspeed

High-Performance Local File Transfer

Lightspeed is a blazingly fast, zero-configuration file transfer tool designed for local networks. Built with Rust, it leverages QUIC (via quinn) for reliable, congested-controlled parallel transport and Memory Mapping for efficient I/O.

Features

• 🚀 High Speed: Utilizes QUIC parallel streams and zero-copy sendfile/pwrite optimizations (Linux).

  Note: The QUIC implementation is currently experimental and a work-in-progress (TODO).

• 🖥️ TUI Interface: Simple, interactive Terminal User Interface built with ratatui.
• 🔍 Zero-Config Discovery: Automatically finds peers on the local LAN using UDP Multicast.
• 🔒 Secure-ish: Uses TLS 1.3 (Self-signed) for encryption during transit.
• 📦 Start & Forget: Just run the binary on two machines; they'll find each other.

Installation

Prerequisites

• Rust Toolchain: Install Rust
• Linux: Recommended for best performance (uses pwrite optimizations).

Build from Source

git clone https://github.com/yourusername/lightspeed.git
cd lightspeed
cargo build --release

The binary will be located at target/release/lightspeed.

Usage

1. Start the application on both the sender and receiver machines:

   ./target/release/lightspeed

2. The TUI will launch:

   • You will see a list of discovered peers on the left.
   • Use Up/Down arrows to select a peer.
   • Press Enter to select a peer and open the file picker.
   • Select a file to send.

3. Receiver:

   • The receiver will automatically accept incoming transfers.
   • Files are saved to the current working directory, renamed with a quic_rec_ prefix (e.g., quic_rec_filename.ext).

Technical Details

• Protocol: QUIC (over single UDP port).
• Discovery: UDP Multicast on 239.255.0.1:9999.
• Concurrency: Breaks files into chunks and sends them over up to 200 parallel QUIC streams.
• Integrity: BLAKE3 hashing is performed on every chunk to ensure data corruption is detected.

Disclaimer

Warning

This project is currently in Alpha.

• It uses self-signed certificates without manual verification (TOFU is not fully implemented), making it vulnerable to active Man-in-the-Middle attacks on untrusted networks.
• QUIC Implementation: The QUIC protocol support is currently a prototype/TODO and may be unstable.
• Use only on trusted local networks.