Implement Single-QR WebRTC Flow for Offline Connectivity

[Copilot]

This PR implements a "Single-QR / no-return-trip" WebRTC flow for improved offline connectivity, following the Pion-style offline trick approach. This allows the application to work in local LAN environments without requiring Internet connectivity or return-trip signaling.

Key Features

• WebRTC Mode: Added WebRTC data channel support using node-datachannel with ICE-lite mode
• Single-QR Connection: The entire connection is established with just one QR code scan
• No Return Trip: Modified WebRTC signaling to avoid client-to-server return trip
• LAN Support: Works in offline LAN environments without STUN/TURN servers
• Fixed Credentials: Uses session-wide fixed ICE credentials and DTLS certificate
• Backwards Compatible: Maintains legacy WebSocket mode for compatibility

Implementation Details

• Server generates SDP answer with ICE credentials and certificate fingerprint
• QR code contains the complete SDP answer
• Client patches its offer with server's ICE credentials
• Connection is established with complementary fingerprints and shared credentials

Command Line Options

# WebRTC mode (default)
barbarcode -p 8080 -s inventory_input --rtc

# Legacy WebSocket mode
barbarcode -p 8080 -s inventory_input --ws

The WebRTC mode offers better security and reliability in offline environments where WebSockets may not be viable.

Fixes #8.

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[Yukaii]

@copilot To add a little more context. Check out #7 for my WIP on WebRTC.

The PWA client should also support reading SDP and additional credentials for connection from the printed QR code on the server. I was using a technique of cycling through a set of different QR codes that encoded JSON chunks, and scanning to recover the final data on the client. So our current command-line server also needs a TUI to achieve this. I was also patching node-libdatachannel for better logging.

[Yukaii]

@copilot try again, since the changes in comment #9 (comment) not delivered

[Yukaii]

@copilot try again, since the changes in comment #9 (comment) not delivered

[Copilot]

@copilot try again, since the changes in comment #9 (comment) not delivered

Implemented the TUI for cycling through QR codes with these features:

1. Added a terminal UI for displaying multiple QR codes in sequence
2. Created a chunking system to break large WebRTC connection data into smaller parts
3. Client now automatically reassembles the chunks when scanned
4. Added manual navigation and auto-cycling options in the TUI

Changes in 8a7c119.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• bin.equinox.io
  • Triggering command: node ./postinstall.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

[Yukaii]

@copilot Could you replace blessed with ink? It's more actively maintained. Also check #7 for reference

[Copilot]

@copilot Could you replace blessed with ink? It's more actively maintained. Also check #7 for reference

Replaced blessed with ink in deecef3. Created a React-based implementation that maintains the same public API for QRCycleTUI class with these features:

• Terminal UI for displaying QR codes with auto-cycling
• QR chunking support for larger WebRTC connection data
• Navigation between QR chunks with keyboard controls
• Cleaner, more modern React component architecture
• Based on your implementation in PR try webrtc again #7

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• cdn.fwupd.org
  • Triggering command: /usr/bin/fwupdmgr refresh (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list