Add a torrent from-link subcommand (#511)

It is now possible to create a torrent file from a magnet link. The
search is performed with minimal concurrency, and so may take a while to
complete.

type: added
fixes: #255

Cargo.toml

@@ -33,6 +33,7 @@ rand              = "0.7.3"
 open              = "1.4.0"
 pretty_assertions = "0.6.0"
 pretty_env_logger = "0.4.0"
+rayon             = "<=1.6.0"
 regex             = "1.0.0"
 serde-hex         = "0.1.0"
 serde_bytes       = "0.11.0"

bin/gen/config.yaml

@@ -19,6 +19,10 @@ examples:
   text:    "Intermodal can be used to create `.torrent` files:"
   code:    "imdl torrent create --input foo"
 
+- command: imdl torrent from-link
+  text:    "Intermodal can be used to create a `.torrent` file from a magnet link:"
+  code:    "imdl torrent from-link magnet:?foo"
+
 - command: imdl torrent show
   text:    "Print information about existing `.torrent` files:"
   code:    "imdl torrent show --input foo.torrent"

src/common.rs

@@ -12,14 +12,14 @@ pub(crate) use std::{
   hash::Hash,
   io::{self, BufRead, BufReader, Cursor, Read, Write},
   iter::{self, Sum},
-  net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, ToSocketAddrs, UdpSocket},
+  net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, TcpStream, ToSocketAddrs, UdpSocket},
   num::{ParseFloatError, ParseIntError, TryFromIntError},
   ops::{AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign},
   path::{self, Path, PathBuf},
   process::ExitStatus,
   str::{self, FromStr},
   string::FromUtf8Error,
-  sync::Once,
+  sync::{mpsc::channel, Once},
   time::{Duration, SystemTime, SystemTimeError},
   usize,
 };
@@ -54,7 +54,9 @@ pub(crate) use url::{Host, Url};
 pub(crate) use log::trace;
 
 // modules
-pub(crate) use crate::{consts, error, host_port_parse_error, magnet_link_parse_error, tracker};
+pub(crate) use crate::{
+  consts, error, host_port_parse_error, magnet_link_parse_error, peer, tracker,
+};
 
 // functions
 pub(crate) use crate::xor_args::xor_args;
@@ -88,9 +90,11 @@ mod test {
   // test stdlib types
   pub(crate) use std::{
     cell::RefCell,
+    net::TcpListener,
     ops::{Deref, DerefMut},
     process::Command,
     rc::Rc,
+    thread,
   };
 
   // test dependencies

src/error.rs

@@ -30,6 +30,8 @@ pub(crate) enum Error {
   Filesystem { source: io::Error, path: PathBuf },
   #[snafu(display("Error searching for files: {}", source))]
   FileSearch { source: ignore::Error },
+  #[snafu(display("Failed to fetch infodict from accessible peers"))]
+  FromLinkNoInfo,
   #[snafu(display("Invalid glob: {}", source))]
   GlobParse { source: globset::Error },
   #[snafu(display("Failed to serialize torrent info dictionary: {}", source))]
@@ -68,6 +70,8 @@ pub(crate) enum Error {
     input: InputTarget,
     source: MetainfoError,
   },
+  #[snafu(display("Network error: {}", source))]
+  Network { source: io::Error },
   #[snafu(display("Failed to invoke opener: {}", source))]
   OpenerInvoke { source: io::Error },
   #[snafu(display("Opener failed: {}", exit_status))]
@@ -114,6 +118,34 @@ pub(crate) enum Error {
     bytes: Bytes,
     source: TryFromIntError,
   },
+  #[snafu(display("Received peer handshake with the wrong infohash"))]
+  PeerHandshakeInfohash,
+  #[snafu(display("Received peer handshake with the wrong protocol header"))]
+  PeerHandshakeHeader,
+  #[snafu(display("Bencoding error: `{}`", source))]
+  PeerMessageBencode { source: bendy::serde::Error },
+  #[snafu(display("Peer extended message payload is malformed"))]
+  PeerMessageExtendedPayload,
+  #[snafu(display("Failed to decode bencoded message: `{}`", source))]
+  PeerMessageFromBencode { source: bendy::serde::Error },
+  #[snafu(display("Peer message payload is too large"))]
+  PeerMessagePayload { source: TryFromIntError },
+  #[snafu(display("Extended handshake has not been received from peer"))]
+  PeerNoExtendedHandshake,
+  #[snafu(display("Received UtMetadata info dict that's failed to deserialize"))]
+  PeerUtMetadataInfoDeserialize { source: bendy::serde::Error },
+  #[snafu(display("Received UtMetadata info dict that's too long"))]
+  PeerUtMetadataInfoLength,
+  #[snafu(display("Received UtMetadata data message that's too long"))]
+  PeerUtMetadataPieceLength,
+  #[snafu(display("Peer doesn't know metadata size"))]
+  PeerUtMetadataMetadataSizeNotKnown,
+  #[snafu(display("Peer doesn't support UtMetadata extension"))]
+  PeerUtMetadataNotSupported,
+  #[snafu(display("Hash of received info dict does not match"))]
+  PeerUtMetadataWrongInfohash,
+  #[snafu(display("Received the wrong UtMetadata piece"))]
+  PeerUtMetadataWrongPiece,
   #[snafu(display("Piece length `{}` is not an even power of two", bytes))]
   PieceLengthUneven { bytes: Bytes },
   #[snafu(display("Piece length must be at least 16 KiB"))]

src/infohash.rs

@@ -62,6 +62,14 @@ impl From<Sha1Digest> for Infohash {
   }
 }
 
+impl From<[u8; 20]> for Infohash {
+  fn from(bytes: [u8; 20]) -> Self {
+    Infohash {
+      inner: Sha1Digest::from_bytes(bytes),
+    }
+  }
+}
+
 impl From<Infohash> for [u8; 20] {
   fn from(infohash: Infohash) -> Self {
     infohash.inner.bytes()

src/lib.rs

@@ -71,6 +71,7 @@ mod mode;
 mod options;
 mod output_stream;
 mod output_target;
+mod peer;
 mod piece_length_picker;
 mod piece_list;
 mod platform;

src/magnet_link.rs

@@ -1,12 +1,12 @@
 use crate::common::*;
 
-#[derive(Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 pub(crate) struct MagnetLink {
-  infohash: Infohash,
-  name: Option<String>,
-  peers: Vec<HostPort>,
-  trackers: Vec<Url>,
-  indices: BTreeSet<u64>,
+  pub(crate) infohash: Infohash,
+  pub(crate) name: Option<String>,
+  pub(crate) peers: Vec<HostPort>,
+  pub(crate) trackers: Vec<Url>,
+  pub(crate) indices: BTreeSet<u64>,
 }
 
 impl MagnetLink {

src/peer.rs

@@ -0,0 +1,6 @@
+pub(crate) use client::Client;
+
+pub(crate) mod client;
+pub(crate) mod connection;
+pub(crate) mod handshake;
+pub(crate) mod message;