Changelog

0.5.0 - 2026-07-22

BEP 9/10 (magnet + ut_metadata): magnet URI parsing, download_magnet/1, LTEP extension protocol, metadata fetch/serve, magnet bootstrap and fetcher supervisors
BEP 11 (ut_pex): peer exchange encode/decode, ingest, and broadcast over LTEP
BEP 32 (IPv6 DHT): separate IPv4/IPv6 routing tables, compact node/peer codecs, dual-stack KRPC and lookup
BEP 42: secure DHT node ID generation from the local IPv4 address
BEP 55 (ut_holepunch): rendezvous/connect/forward hole-punch messages over LTEP; Peer.Holepunch.Store for punch state
DHT (BEP 5): routing-table persistence across restarts, dual-stack socket wiring, runtime node-id path fix
NAT traversal: NAT-PMP and UPnP IGD port-mapping clients, STUN mapping-behaviour detection, NAT.PortMapper orchestrator
MSE/PE: Message Stream Encryption handshake and RC4 transport layer over Peer.Transport
uTP (BEP 29): zombie-connection hardening and BEP 29 off-spec bug fixes
Peer discovery/dial: Peer.Endpoints, sticky dial backoff with churn and hard-fail escalation, Peer.DialStats per address-family outcomes
Acceptor: global IPv4/IPv6 address helpers, IpCache periodic getifaddrs snapshot via :persistent_term, dual-stack listen logging; LTEP handshakes advertise listen port and global addresses
README: BEP 9, 10, 11, 32, 42, and 55 rows in Supported BEPs table; download_magnet/1 in public API table

Peer I/O: MSE/PE encryption integrated into the peer transport and sender receive path
Peer dial: immediate-drop churn backoff, endpoint PID lookup via Peer.Endpoints.get_pid/3

Started at runtime (via ElixirTorrentApplication): TCP acceptor (with IpCache), PeerDiscovery, magnet fetcher/bootstrap, and Peer.Holepunch.Store
Implemented and compiled, not started in supervision: mainline DHT server, uTP dispatcher, NAT.PortMapper, Peer.Endpoints, Peer.DialBackoff, and Peer.DialStats — wiring deferred to a future release
Default peer acquisition remains TCP + tracker (plus magnet metadata bootstrap); DHT announce, uTP fallback dials, NAT mapping, and full hole-punch initiation require the dormant services above

BEP 29 (uTP): Peer.Transport over TCP and uTP; uTP packet stack with LEDBAT; connection lifecycle and dispatcher; dial backoff and endpoint registry; outbound TCP-first dial with uTP fallback; inbound uTP handshake entry
BEP 5 (DHT): Mainline DHT KRPC node (ping, find_node, get_peers, announce_peer); k-bucket routing table with bootstrap routers; iterative lookup and announce token workflow; DHT and uTP share one UDP socket via DHT.send_udp/3
README: BEP 5 (Mainline DHT) row in Supported BEPs table

Peer I/O: Peer.Sender is the sole socket owner over Peer.Transport; Peer.Receiver removed; post-handshake socket handoff uses Sender.activate/1

Torrent progress and downloaded/left counters reconciled with the on-disk bitfield
Piece pipeline: idempotent piece statistics init, stale :processing cleanup, exclude-aware picker
In-flight piece download recovery when subpiece requests stall (waiting: [] no longer finishes early)
Incoming piece block bounds validation; Peer.log_id/1 for safe timeout logging
Download scheduler: parallel piece picking with availability checks, resume handoff before controller scheduling, per-piece interested peer assignment

uTP (BEP 29) and DHT (BEP 5) are implemented and compiled in, but runtime activation (supervision wiring) is deferred to a future release; the default peer-acquisition/download path remains TCP + tracker-based.

ElixirTorrent.download/2 accepts an optional :download_dir keyword — base directory for downloaded files (defaults to File.cwd!/0)
Session snapshots remain under {File.cwd!()}/.elixir_torrent/state/ regardless of :download_dir
remove/2 with delete_data: true removes files from the torrent's download directory

Multi-file torrents whose files share no common top-level folder are written under a directory named after the torrent (sanitized info.name)
Multi-file torrents that already use a shared root folder (e.g. dir/a.bin, dir/b.bin) keep their original paths
Single-file torrents are written directly into the download root

Saved session state under .elixir_torrent/state/{info_hash}.term (relative to File.cwd!/0)
On download/1, an existing session is loaded and the bitfield is verified against disk before resuming
remove/2 deletes the session file; delete_data: true also removes downloaded files

stop_and_serialize/1 — stop piece downloads, disconnect peers (BEP 3), send tracker event=stopped, persist session, then stop the torrent process
stop_all_and_serialize/0 — same for every active torrent
list/0 — returns info hashes for all running torrent processes

Peers receive BEP 3 cancel / not interested / choke before TCP connections close
Used during shutdown so peers are notified cleanly

ElixirTorrent.list_files/1 — file list with per-file download progress
ElixirTorrent.remove/2 — stop a torrent; optional delete_data: true removes files from disk
Requires Elixir ~> 1.20

First public release — BitTorrent client engine publishable as a Hex dependency.

Public API

Protocol & networking

Peer wire protocol (BEP 3) with choking, rarest-first piece selection, and endgame mode
Fast Extension (BEP 6) — allowed_fast, reject on choked requests
IPv6 tracker peers (peers6) and dual-stack listen sockets
Multi-homed HTTP announce (BEP 7) over IPv4 and IPv6
HTTP and UDP trackers (BEP 15), compact peer lists (BEP 23)

Reliability

Improved choke recovery, piece availability tracking, and tracker announce handling