Implement FromStr for MagnetLink

type: added

Cargo.toml

@@ -22,6 +22,7 @@ atty              = "0.2.0"
 chrono            = "0.4.1"
 console           = "0.12.0"
 globset           = "0.4.0"
+hex               = "0.4.2"
 ignore            = "0.4.14"
 lazy_static       = "1.4.0"
 lexiclean         = "0.0.1"

src/common.rs

@@ -52,7 +52,7 @@ pub(crate) use url::{Host, Url};
 pub(crate) use log::trace;
 
 // modules
-pub(crate) use crate::{consts, error, host_port_parse_error};
+pub(crate) use crate::{consts, error, host_port_parse_error, magnet_link_parse_error};
 
 // functions
 pub(crate) use crate::xor_args::xor_args;
@@ -69,12 +69,13 @@ pub(crate) use crate::{
   file_info::FileInfo, file_path::FilePath, file_status::FileStatus, files::Files, hasher::Hasher,
   host_port::HostPort, host_port_parse_error::HostPortParseError, info::Info, infohash::Infohash,
   input::Input, input_target::InputTarget, lint::Lint, linter::Linter, magnet_link::MagnetLink,
-  md5_digest::Md5Digest, metainfo::Metainfo, metainfo_error::MetainfoError, mode::Mode,
-  options::Options, output_stream::OutputStream, output_target::OutputTarget,
-  piece_length_picker::PieceLengthPicker, piece_list::PieceList, platform::Platform,
-  sha1_digest::Sha1Digest, shell::Shell, sort_key::SortKey, sort_order::SortOrder,
-  sort_spec::SortSpec, status::Status, style::Style, subcommand::Subcommand, table::Table,
-  torrent_summary::TorrentSummary, use_color::UseColor, verifier::Verifier, walker::Walker,
+  magnet_link_parse_error::MagnetLinkParseError, md5_digest::Md5Digest, metainfo::Metainfo,
+  metainfo_error::MetainfoError, mode::Mode, options::Options, output_stream::OutputStream,
+  output_target::OutputTarget, piece_length_picker::PieceLengthPicker, piece_list::PieceList,
+  platform::Platform, sha1_digest::Sha1Digest, shell::Shell, sort_key::SortKey,
+  sort_order::SortOrder, sort_spec::SortSpec, status::Status, style::Style, subcommand::Subcommand,
+  table::Table, torrent_summary::TorrentSummary, use_color::UseColor, verifier::Verifier,
+  walker::Walker,
 };
 
 // type aliases

src/error.rs

@@ -44,6 +44,11 @@ pub(crate) enum Error {
   Internal { message: String },
   #[snafu(display("Unknown lint: {}", text))]
   LintUnknown { text: String },
+  #[snafu(display("Failed to parse magnet link `{}`: {}", text, source))]
+  MagnetLinkParse {
+    text: String,
+    source: MagnetLinkParseError,
+  },
   #[snafu(display("Failed to deserialize torrent metainfo from {}: {}", input, source))]
   MetainfoDeserialize {
     source: bendy::serde::Error,

src/infohash.rs

@@ -56,6 +56,12 @@ impl Infohash {
   }
 }
 
+impl From<Sha1Digest> for Infohash {
+  fn from(inner: Sha1Digest) -> Self {
+    Self { inner }
+  }
+}
+
 impl Into<Sha1Digest> for Infohash {
   fn into(self) -> Sha1Digest {
     self.inner

src/lib.rs

@@ -75,6 +75,7 @@ mod invariant;
 mod lint;
 mod linter;
 mod magnet_link;
+mod magnet_link_parse_error;
 mod md5_digest;
 mod metainfo;
 mod metainfo_error;

src/magnet_link.rs

@@ -1,5 +1,6 @@
 use crate::common::*;
 
+#[derive(Debug, PartialEq)]
 pub(crate) struct MagnetLink {
   infohash: Infohash,
   name: Option<String>,
@@ -22,7 +23,7 @@ impl MagnetLink {
     Ok(link)
   }
 
-  pub(crate) fn with_infohash(infohash: Infohash) -> MagnetLink {
+  pub(crate) fn with_infohash(infohash: Infohash) -> Self {
     MagnetLink {
       infohash,
       name: None,
@@ -37,7 +38,6 @@ impl MagnetLink {
     self.name = Some(name.into());
   }
 
-  #[allow(dead_code)]
   pub(crate) fn add_peer(&mut self, peer: HostPort) {
     self.peers.push(peer);
   }
@@ -84,6 +84,74 @@ impl MagnetLink {
 
     url
   }
+
+  fn parse(text: &str) -> Result<Self, MagnetLinkParseError> {
+    let url = Url::parse(&text).context(magnet_link_parse_error::URL)?;
+
+    if url.scheme() != "magnet" {
+      return Err(MagnetLinkParseError::Scheme {
+        scheme: url.scheme().into(),
+      });
+    }
+
+    let mut link = None;
+    for (k, v) in url.query_pairs() {
+      if k.as_ref() == "xt" {
+        if let Some(infohash) = v.strip_prefix("urn:btih:") {
+          if infohash.len() != 40 {
+            return Err(MagnetLinkParseError::InfohashLength {
+              text: infohash.into(),
+            });
+          }
+
+          let buf = hex::decode(infohash).context(magnet_link_parse_error::HexParse {
+            text: infohash.to_string(),
+          })?;
+
+          link = Some(MagnetLink::with_infohash(
+            Sha1Digest::from_bytes(
+              buf
+                .as_slice()
+                .try_into()
+                .invariant_unwrap("bounds are checked above"),
+            )
+            .into(),
+          ));
+
+          break;
+        }
+      }
+    }
+
+    let mut link = link.ok_or(MagnetLinkParseError::TopicMissing)?;
+
+    for (k, v) in url.query_pairs() {
+      match k.as_ref() {
+        "tr" => link.add_tracker(Url::parse(&v).context(
+          magnet_link_parse_error::TrackerAddress {
+            text: v.to_string(),
+          },
+        )?),
+        "dn" => link.set_name(v),
+        "x.pe" => link.add_peer(HostPort::from_str(&v).context(
+          magnet_link_parse_error::PeerAddress {
+            text: v.to_string(),
+          },
+        )?),
+        _ => {}
+      }
+    }
+
+    Ok(link)
+  }
+}
+
+impl FromStr for MagnetLink {
+  type Err = Error;
+
+  fn from_str(text: &str) -> Result<Self, Self::Err> {
+    Self::parse(text).context(error::MagnetLinkParse { text })
+  }
 }
 
 impl Display for MagnetLink {
@@ -179,4 +247,114 @@ mod tests {
       ),
     );
   }
+
+  #[test]
+  fn link_from_str_round_trip() {
+    let mut link_to = MagnetLink::with_infohash(Infohash::from_bencoded_info_dict("".as_bytes()));
+
+    link_to.set_name("foo");
+    link_to.add_tracker(Url::parse("http://foo.com/announce").unwrap());
+    link_to.add_tracker(Url::parse("http://bar.net/announce").unwrap());
+    link_to.add_peer("foo.com:1337".parse().unwrap());
+    link_to.add_peer("bar.net:666".parse().unwrap());
+
+    let link_from = MagnetLink::from_str(&link_to.to_url().to_string()).unwrap();
+
+    assert_eq!(link_to, link_from);
+  }
+
+  #[test]
+  fn link_from_str_url_error() {
+    let link = "%imdl.io";
+    let e = MagnetLink::from_str(link).unwrap_err();
+
+    assert_matches!(e, Error::MagnetLinkParse {
+      text,
+      source: MagnetLinkParseError::URL { .. },
+    } if text == link);
+  }
+
+  #[test]
+  fn link_from_str_scheme_error() {
+    let link = "mailto:?alice@imdl.io";
+
+    let e = MagnetLink::from_str(link).unwrap_err();
+    assert_matches!(e, Error::MagnetLinkParse {
+      text,
+      source: MagnetLinkParseError::Scheme { scheme },
+    } if text == link && scheme == "mailto");
+  }
+
+  #[test]
+  fn link_from_str_infohash_length_error() {
+    let infohash = "123456789abcedf";
+    let link = format!("magnet:?xt=urn:btih:{}", infohash);
+    let e = MagnetLink::from_str(&link).unwrap_err();
+
+    assert_matches!(e, Error::MagnetLinkParse {
+      text,
+      source: MagnetLinkParseError::InfohashLength { text: ih },
+    } if text == link && infohash == ih);
+  }
+
+  #[test]
+  fn link_from_str_infohash_bad_hex() {
+    let infohash = "laaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+    let link = format!("magnet:?xt=urn:btih:{}", infohash);
+    let e = MagnetLink::from_str(&link).unwrap_err();
+
+    assert_matches!(e, Error::MagnetLinkParse {
+      text,
+      source: MagnetLinkParseError::HexParse {
+        text: ih,
+        source: _,
+      }} if text == link && infohash == ih);
+  }
+
+  #[test]
+  fn link_from_str_topic_missing() {
+    let link = "magnet:?";
+    let e = MagnetLink::from_str(&link).unwrap_err();
+
+    assert_matches!(e,
+      Error::MagnetLinkParse {
+        text,
+        source: MagnetLinkParseError::TopicMissing,
+      } if text == link);
+  }
+
+  #[test]
+  fn link_from_str_tracker_address() {
+    let infohash = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+    let bad_addr = "%imdl.io/announce";
+    let link = format!("magnet:?xt=urn:btih:{}&tr={}", infohash, bad_addr);
+    let e = MagnetLink::from_str(&link).unwrap_err();
+
+    assert_matches!(e,
+      Error::MagnetLinkParse {
+      text,
+      source: MagnetLinkParseError::TrackerAddress {
+        text: addr,
+        source: _,
+      },
+    } if text == link && addr == bad_addr);
+  }
+
+  #[test]
+  fn link_from_str_peer_address() {
+    let infohash = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+    let bad_addr = "%imdl.io:13337";
+    let link = format!("magnet:?xt=urn:btih:{}&x.pe={}", infohash, bad_addr);
+    let e = MagnetLink::from_str(&link).unwrap_err();
+
+    assert_matches!(e,
+      Error::MagnetLinkParse {
+        text,
+        source: MagnetLinkParseError::PeerAddress {
+          text: addr,
+          source: _,
+        }
+      } if text == link && addr == bad_addr
+    );
+  }
 }

src/magnet_link_parse_error.rs

@@ -0,0 +1,32 @@
+use crate::common::*;
+
+#[derive(Debug, Snafu)]
+#[snafu(visibility(pub(crate)))]
+pub(crate) enum MagnetLinkParseError {
+  #[snafu(display("Failed to parse hex string `{}`: {}", text, source))]
+  HexParse {
+    text: String,
+    source: hex::FromHexError,
+  },
+  #[snafu(display("Hex-encoded infohash, `{}`, is not 40 characters long", text))]
+  InfohashLength { text: String },
+  #[snafu(display("Failed to parse peer address `{}`: {}", text, source))]
+  PeerAddress {
+    text: String,
+    source: HostPortParseError,
+  },
+  #[snafu(display(
+    "Invalid scheme: `{}`. Magnet links must use the `magnet:` scheme",
+    scheme
+  ))]
+  Scheme { scheme: String },
+  #[snafu(display("Magnet link must have a topic that begins with `urn:btih:`"))]
+  TopicMissing,
+  #[snafu(display("Failed to parse tracker address `{}`: {}", text, source))]
+  TrackerAddress {
+    text: String,
+    source: url::ParseError,
+  },
+  #[snafu(display("Failed to parse URL: {}", source))]
+  URL { source: url::ParseError },
+}