webtranscat

A WebTransport equivalent of websocat - a command-line WebTransport client for debugging and testing.

webtranscat was originally developed to debug videocall.rs, a WebRTC video calling application that uses WebTransport for data channels.

Features

• 🔗 WebTransport Client: Connect to WebTransport servers using QUIC
• 📡 Datagram Support: Send and receive unreliable datagrams
• 🌊 Stream Support: Handle reliable unidirectional streams
• 🔄 Bidirectional: Echo incoming data and send stdin input
• 🔧 websocat-like CLI: Familiar interface for websocat users
• 🛡️ Security Options: Support for both secure and insecure connections
• 📊 Verbose Logging: Multiple verbosity levels for debugging

Installation

From crates.io

cargo install webtranscat

From source

git clone https://github.com/securityunion/webtranscat.git
cd webtranscat
cargo install --path .

Usage

Basic Examples

# Connect to a WebTransport server (interactive mode)
webtranscat https://example.com:4443

# Connect with verbose logging
webtranscat -v https://example.com:4443

# Connect with insecure certificate verification (for testing)
webtranscat --insecure https://localhost:4443

# Listen-only mode (don't send stdin input)
webtranscat -u https://example.com:4443

# Exit after receiving one message
webtranscat -1 https://example.com:4443

# Multiple verbosity levels (like websocat)
webtranscat -vv https://example.com:4443   # Debug level
webtranscat -vvv https://example.com:4443  # Trace level

# Quiet mode (suppress diagnostic messages)
webtranscat -q https://example.com:4443

Environment Variables

# Override logging with RUST_LOG
RUST_LOG=debug webtranscat https://example.com:4443

# Early startup debugging
WEBTRANSCAT_EARLY_LOG=1 webtranscat https://example.com:4443

Command Line Options

Usage: webtranscat [OPTIONS] <URL>

Arguments:
  <URL>  WebTransport URL to connect to

Options:
  -v...                 Increase verbosity level to info or further
  -q                    Suppress all diagnostic messages, except of startup errors
      --insecure        Skip certificate verification (insecure)
  -u, --unidirectional  Only listen for incoming data, don't send from stdin
  -1, --one-message     Exit after receiving one message
  -h, --help            Print help
  -V, --version         Print version

How it Works

webtranscat establishes a WebTransport connection and concurrently:

1. Listens for incoming datagrams - unreliable, unordered packets (UDP-like but encrypted)
2. Accepts unidirectional streams - reliable, ordered byte streams (TCP-like but multiplexed)
3. Sends stdin input as datagrams - user input becomes outgoing datagrams (unless -u is used)

All received data is echoed to stdout with newlines, making it easy to see what's being received.

Logging Levels

Following websocat's logging approach:

• No flags: WARN level (warnings + errors only)
• -v: INFO level (connection info + warnings + errors)
• -vv: DEBUG level (detailed debugging info)
• -vvv+: TRACE level (everything)

Development Origin

This tool was created to debug videocall.rs, a WebRTC video calling application that leverages WebTransport for efficient data channel communication. During development, we needed a simple way to test WebTransport connections, inspect datagrams and streams, and debug connectivity issues.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Disclaimer

This tool is primarily intended for debugging and testing. While it supports secure connections, please review the security implications before using in production environments.