Feat torrent to magnet

CHANGELOG.md

@@ -14,6 +14,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `TorrentFile`, `DecodedTorrent` and `DecodedInfo` implement `PartialEq`
 - `MagnetFile` implements `FromStr`, `TryFrom<String>`, and `Into<String>`
 - `MagnetFile` supports serde de/serialization
+- `PeerSource`, `Tracker` and `TrackerScheme` now derive `Eq`, `PartialOrd`
+  and `Ord` so that they can be sorted in collections
+- `TorrentFile::trackers` returns the trackers in the torrent file, sorted
+  and deduplicated; the sort order is not specified
+- `TorrentFile::magnet_link` produces a `MagnetLink` that's roughly equivalent
+  to the torrent file; some information may not be ported over, and this is
+  a one-way operation
+
+### Changed
+
+- `MagnetFile` sorts and deduplicates the trackers provided in the magnet URL;
+  `MagnetFile::trackers` returns them in an order, which is not specified
+
+### Fixed
+
+- `MagnetLink` equality is no longer affected by the exact representation of the
+  magnet URL; if the name, hash, and (sorted/deduped) trackers are equal, then
+  two magnets are considered equal
 
 ## Version 0.4.0 (2025-11-10)
 

src/magnet.rs

@@ -262,6 +262,11 @@ impl MagnetLink {
             hash1.hybrid(hash2)?
         };
 
+        // Reorder the trackers to provide equality
+        trackers.sort_unstable();
+        // Remove duplicates
+        trackers.dedup();
+
         Ok(MagnetLink {
             hash: final_hash,
             name: name.to_string(),
@@ -317,6 +322,9 @@ impl MagnetLink {
     }
 
     /// Returns the list of [`Tracker`](crate::tracker::Tracker) for the MagnetLink.
+    ///
+    /// The list is guaranteed to be sorted in a specific order and deduplicated,
+    /// but the order is not specified.
     pub fn trackers(&self) -> &[Tracker] {
         &self.trackers
     }
@@ -330,7 +338,14 @@ impl std::fmt::Display for MagnetLink {
 
 impl PartialEq for MagnetLink {
     fn eq(&self, other: &Self) -> bool {
-        self.query == other.query
+        // Here we may have different ordering of the URL params so we check the
+        // values. This is more expensive but more correct.
+        //
+        // In the future, we may optimize this by reproducing a normalized query.
+        self.name == other.name
+            && self.hash == other.hash
+            // Trackers have been sorted in the constructor
+            && self.trackers == other.trackers
     }
 }
 
@@ -360,16 +375,14 @@ impl From<MagnetLink> for String {
 mod tests {
     use super::*;
 
-    use crate::TrackerScheme;
-
     #[test]
     fn can_load_v1() {
         let magnet_source =
             std::fs::read_to_string("tests/bittorrent-v1-emma-goldman.magnet").unwrap();
         let magnet = MagnetLink::new(&magnet_source).unwrap();
         assert_eq!(
             magnet.name,
-            "Emma Goldman - Essential Works of Anarchism (16 books)".to_string()
+            "Goldman, Emma - Essential Works of Anarchism".to_string()
         );
         assert_eq!(
             magnet.hash,
@@ -540,15 +553,38 @@ mod tests {
     #[test]
     fn can_parse_magnet_trackers() {
         let expected = &[
+            "http://tracker.tfile.co:80/announce",
+            "udp://9.rarbg.me:2730/announce",
+            "udp://9.rarbg.me:2740/announce",
+            "udp://9.rarbg.me:2770/announce",
+            "udp://9.rarbg.to:2710/announce",
+            "udp://9.rarbg.to:2720/announce",
+            "udp://9.rarbg.to:2730/announce",
+            "udp://9.rarbg.to:2740/announce",
+            "udp://9.rarbg.to:2770/announce",
+            "udp://bt.xxx-tracker.com:2710/announce",
+            "udp://denis.stalker.upeer.me:6969/announce",
+            "udp://eddie4.nl:6969/announce",
+            "udp://exodus.desync.com:6969/announce",
+            "udp://ipv4.tracker.harry.lu:80/announce",
+            "udp://ipv6.tracker.harry.lu:80/announce",
+            "udp://open.demonii.si:1337/announce",
+            "udp://open.stealth.si:80/announce",
+            "udp://retracker.lanta-net.ru:2710/announce",
+            "udp://torrentclub.tech:6969/announce",
             "udp://tracker.coppersurfer.tk:6969/announce",
-            "udp://tracker.opentrackr.org:1337/announce",
-            "udp://exodus.desync.com:6969",
-            "udp://tracker.opentrackr.org:1337/announce",
-            "http://tracker.openbittorrent.com:80/announce",
-            "udp://opentracker.i2p.rocks:6969/announce",
+            "udp://tracker.cyberia.is:6969/announce",
             "udp://tracker.internetwarriors.net:1337/announce",
+            "udp://tracker.justseed.it:1337/announce",
             "udp://tracker.leechers-paradise.org:6969/announce",
-            "udp://coppersurfer.tk:6969/announce",
+            "udp://tracker.mg64.net:6969/announce",
+            "udp://tracker.moeking.me:6969/announce",
+            "udp://tracker.open-internet.nl:6969/announce",
+            "udp://tracker.opentrackr.org:1337/announce",
+            "udp://tracker.pirateparty.gr:6969/announce",
+            "udp://tracker.port443.xyz:6969/announce",
+            "udp://tracker.tiny-vps.com:6969/announce",
+            "udp://tracker.torrent.eu.org:451/announce",
             "udp://tracker.zer0day.to:1337/announce",
         ];
 
@@ -562,19 +598,6 @@ mod tests {
             .map(|tracker| tracker.url().to_string())
             .collect::<Vec<_>>();
 
-        // Did we find all trackers?
-        assert_eq!(found.len(), expected.len(),);
-        // Did we find that there's 1 HTTP tracker?
-        assert_eq!(
-            magnet
-                .trackers
-                .into_iter()
-                .filter(|tracker| tracker.scheme() == &TrackerScheme::Http)
-                .collect::<Vec<_>>()
-                .len(),
-            1
-        );
-        // Do we have the correct list?
         assert_eq!(found, expected);
 
         let magnet_url = std::fs::read_to_string("tests/bittorrent-v2-test.magnet").unwrap();

src/torrent_file.rs

@@ -1,4 +1,8 @@
 use bt_bencode::Value as BencodeValue;
+use fluent_uri::pct_enc::{
+    encoder::{Data, Query},
+    EStr, EString,
+};
 use rustc_hex::ToHex;
 #[cfg(feature = "sea_orm")]
 use sea_orm::prelude::*;
@@ -8,7 +12,10 @@ use sha1::{Digest, Sha1};
 use std::collections::HashMap;
 use std::path::PathBuf;
 
-use crate::{InfoHash, InfoHashError, PieceLength, TorrentContent, TorrentID, Tracker};
+use crate::{
+    InfoHash, InfoHashError, MagnetLink, MagnetLinkError, PieceLength, TorrentContent, TorrentID,
+    Tracker,
+};
 
 /// Error occurred during parsing a [`TorrentFile`](crate::torrent_file::TorrentFile).
 #[derive(Clone, Debug, PartialEq)]
@@ -330,6 +337,70 @@ impl TorrentFile {
     pub fn id(&self) -> TorrentID {
         TorrentID::from_infohash(&self.hash)
     }
+
+    /// List the trackers in the torrent, ensuring
+    /// they're sorted and deduplicated.
+    pub fn trackers(&self) -> Vec<Tracker> {
+        let mut trackers = vec![];
+        if let Some(tracker) = &self.decoded.announce {
+            trackers.push(tracker.clone());
+        }
+
+        for tier in &self.decoded.announce_list {
+            for tracker in tier {
+                trackers.push(tracker.clone());
+            }
+        }
+
+        trackers.sort_unstable();
+        trackers.dedup();
+
+        trackers
+    }
+
+    /// Lossy transformation into a [`MagnetLink`].
+    ///
+    /// This is a lossy operation because:
+    ///
+    /// - magnet links do not contain detailed pieces information,
+    ///   so there is no reverse operation without network resolution
+    /// - not all metadata about the torrent may be added to the magnet link
+    ///
+    /// What's added to the magnet link:
+    ///
+    /// - name
+    /// - torrentID
+    /// - trackers
+    ///
+    /// For the moment, this is a fallible operation because we make sure
+    /// the produced MagnetLink can be parsed again. This operation may not
+    /// produce errors in a future release.
+    pub fn magnet_link(&self) -> Result<MagnetLink, MagnetLinkError> {
+        // Not sure how to build a URI with `magnet:` and not `magnet://`
+        // without the `Uri::builder`.
+        let mut uri = match &self.hash {
+            InfoHash::V1(h) => format!("magnet:?xt=urn:btih:{h}"),
+            InfoHash::V2(h) => format!("magnet:?xt=urn:btmh:1220{h}"),
+            InfoHash::Hybrid((h1, h2)) => format!("magnet:?xt=urn:btih:{h1}&xt=urn:btmh:1220{h2}"),
+        };
+
+        let mut buf = EString::<Query>::new();
+
+        if !self.name.is_empty() {
+            buf.push_estr(EStr::new_or_panic("&dn="));
+            buf.encode_str::<Data>(&self.name);
+        }
+
+        // We use the helper to avoid duplicates or unsorted entries
+        for tracker in self.trackers() {
+            buf.push_estr(EStr::new_or_panic("&tr="));
+            buf.encode_str::<Data>(tracker.url());
+        }
+
+        uri.push_str(buf.as_str());
+
+        MagnetLink::new(&uri)
+    }
 }
 
 #[cfg(feature = "sea_orm")]
@@ -509,4 +580,57 @@ mod tests {
         let res = TorrentFile::from_slice(&slice);
         assert!(res.is_err());
     }
+
+    #[test]
+    fn test_torrent_to_magnet_v2() {
+        let slice = std::fs::read("tests/bittorrent-v2-test.torrent").unwrap();
+        let res = TorrentFile::from_slice(&slice);
+        let torrent = res.unwrap();
+
+        let expected = std::fs::read_to_string("tests/bittorrent-v2-test.magnet").unwrap();
+        let magnet = torrent.magnet_link().unwrap();
+        assert_eq!(expected, magnet.to_string(),);
+    }
+
+    #[test]
+    fn test_torrent_to_magnet_hybrid() {
+        let slice = std::fs::read("tests/bittorrent-v2-hybrid-test.torrent").unwrap();
+        let res = TorrentFile::from_slice(&slice);
+        let torrent = res.unwrap();
+
+        let expected = std::fs::read_to_string("tests/bittorrent-v2-hybrid-test.magnet").unwrap();
+        let magnet = torrent.magnet_link().unwrap();
+        assert_eq!(expected, magnet.to_string(),);
+    }
+
+    #[test]
+    fn test_torrent_to_magnet_v1() {
+        let slice = std::fs::read("tests/bittorrent-v1-emma-goldman.torrent").unwrap();
+        let res = TorrentFile::from_slice(&slice);
+        let torrent = res.unwrap();
+
+        let expected = MagnetLink::new(
+            &std::fs::read_to_string("tests/bittorrent-v1-emma-goldman.magnet").unwrap(),
+        )
+        .unwrap();
+        let magnet = torrent.magnet_link().unwrap();
+
+        assert_eq!(expected.name(), magnet.name(),);
+
+        assert_eq!(expected.hash(), magnet.hash(),);
+
+        // Check for duplicates. This is useful because the `announce` in a torrent
+        // file may also be in the `announce_list` so we wanna make sure we don't have it twice.
+        for tracker in magnet.trackers() {
+            if magnet.trackers().iter().filter(|x| x == &tracker).count() > 1 {
+                panic!("Duplicate tracker: {tracker:?}");
+            }
+        }
+
+        // Check the trackers are actually equal
+        assert_eq!(magnet.trackers(), expected.trackers());
+
+        // Check for complete equality in this specific case (no information loss on the test)
+        assert_eq!(expected, magnet);
+    }
 }

src/tracker.rs

@@ -4,7 +4,7 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use std::str::FromStr;
 
 /// A source of peers. Can be a [`Tracker`](crate::tracker::Tracker) or a decentralized source.
-#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub enum PeerSource {
     DHT,
     PEX,
@@ -16,7 +16,7 @@ pub enum PeerSource {
 ///
 /// This is usually parsed directly from a [`TorrentFile`](crate::torrent_file::TorrentFile)
 /// or a [`MagnetLink`](crate::magnet::MagnetLink).
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Tracker {
     /// Tracker URL scheme (usually `ws`, `http(s)`, or `udp`)
     scheme: TrackerScheme,
@@ -94,7 +94,7 @@ impl FromStr for Tracker {
 /// Does not implement Serialize/Deserialize because it's actually not in the
 /// torrent data. It is constructed from the parsed tracker URLs contained in
 /// the torrent data.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum TrackerScheme {
     Websocket,
     Http,

tests/bittorrent-v1-emma-goldman.magnet

@@ -1 +1 @@
-magnet:?xt=urn:btih:C811B41641A09D192B8ED81B14064FFF55D85CE3&dn=Emma+Goldman+-+Essential+Works+of+Anarchism+%2816+books%29&tr=udp%3A%2F%2Ftracker.coppersurfer.tk%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce&tr=udp%3A%2F%2Fexodus.desync.com%3A6969&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce&tr=http%3A%2F%2Ftracker.openbittorrent.com%3A80%2Fannounce&tr=udp%3A%2F%2Fopentracker.i2p.rocks%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.internetwarriors.net%3A1337%2Fannounce&tr=udp%3A%2F%2Ftracker.leechers-paradise.org%3A6969%2Fannounce&tr=udp%3A%2F%2Fcoppersurfer.tk%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.zer0day.to%3A1337%2Fannounce
+magnet:?xt=urn:btih:c811b41641a09d192b8ed81b14064fff55d85ce3&dn=Goldman%2C%20Emma%20-%20Essential%20Works%20of%20Anarchism&xl=80121936&tr=udp%3A%2F%2Ftracker.leechers-paradise.org%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.internetwarriors.net%3A1337%2Fannounce&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce&tr=udp%3A%2F%2Ftracker.coppersurfer.tk%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.pirateparty.gr%3A6969%2Fannounce&tr=udp%3A%2F%2F9.rarbg.to%3A2730%2Fannounce&tr=udp%3A%2F%2F9.rarbg.to%3A2710%2Fannounce&tr=udp%3A%2F%2Fbt.xxx-tracker.com%3A2710%2Fannounce&tr=udp%3A%2F%2Ftracker.cyberia.is%3A6969%2Fannounce&tr=udp%3A%2F%2Fretracker.lanta-net.ru%3A2710%2Fannounce&tr=udp%3A%2F%2F9.rarbg.to%3A2770%2Fannounce&tr=udp%3A%2F%2F9.rarbg.me%3A2730%2Fannounce&tr=udp%3A%2F%2Feddie4.nl%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.mg64.net%3A6969%2Fannounce&tr=udp%3A%2F%2Fopen.demonii.si%3A1337%2Fannounce&tr=udp%3A%2F%2Ftracker.zer0day.to%3A1337%2Fannounce&tr=udp%3A%2F%2Ftracker.tiny-vps.com%3A6969%2Fannounce&tr=udp%3A%2F%2Fipv6.tracker.harry.lu%3A80%2Fannounce&tr=udp%3A%2F%2F9.rarbg.me%3A2740%2Fannounce&tr=udp%3A%2F%2F9.rarbg.me%3A2770%2Fannounce&tr=udp%3A%2F%2Fdenis.stalker.upeer.me%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.port443.xyz%3A6969%2Fannounce&tr=udp%3A%2F%2Ftracker.moeking.me%3A6969%2Fannounce&tr=udp%3A%2F%2Fexodus.desync.com%3A6969%2Fannounce&tr=udp%3A%2F%2F9.rarbg.to%3A2740%2Fannounce&tr=udp%3A%2F%2F9.rarbg.to%3A2720%2Fannounce&tr=udp%3A%2F%2Ftracker.justseed.it%3A1337%2Fannounce&tr=udp%3A%2F%2Ftracker.torrent.eu.org%3A451%2Fannounce&tr=udp%3A%2F%2Fipv4.tracker.harry.lu%3A80%2Fannounce&tr=udp%3A%2F%2Ftracker.open-internet.nl%3A6969%2Fannounce&tr=udp%3A%2F%2Ftorrentclub.tech%3A6969%2Fannounce&tr=udp%3A%2F%2Fopen.stealth.si%3A80%2Fannounce&tr=http%3A%2F%2Ftracker.tfile.co%3A80%2Fannounce