C Torrent Client

Current features:

• Supports single and multi-file torrents
• Asynchronous I/O Engine: non-blocking salect() event loop. Handles 50+ concurrent peer connections on a single thread with zero context-switching.
• Request Pipelining
• Magnet Link Support: BEP 9 (Extension Protocol) to handshake and fetch metadata without .torrent files.
• UDP Tracker Protocol (BEP 15)
• Connection Pool replenishes stalled/choked connections automatically and performs async scans to find faster peers.
• Integrity Checking - SHA-1 hash to verify pieces before downloading
• Capable of parsing Multi-file metadata & mapping blocks to the correct file offsets on disk.

TODO

• Prioritize rare pieces
• Add Network Byte Order helper functions for systems that don't come native with one htols(), etc.
• Seeding!
• Parse bencode in BEP 10 Extension Handshake Response (metadata.c)
• Resume Capability: save bitfield state to disk and resume downloads after restarting.

Install

To compile and run:

git clone https://github.com/elliota43/torrent-client-c.git/

cd torrent-client-c

# configure
cmake -S . -B build

# build
cmake --build build

./build/torrent_client ~/path/to/file.torrent

#OR

./build/torrent_client "MAGNET_URI"

Note: Deprecation warnings are silenced because SHA1 is technically deprecated, but is essential to the BitTorrent protocol.