Initial commit

.gitignore

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+/target
+
+# Created by https://www.toptal.com/developers/gitignore/api/rust,jetbrains+all,vim
+# Edit at https://www.toptal.com/developers/gitignore?templates=rust,jetbrains+all,vim
+
+### JetBrains+all ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# AWS User-specific
+.idea/**/aws.xml
+
+# Generated files
+.idea/**/contentModel.xml
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Gradle and Maven with auto-import
+# When using Gradle or Maven with auto-import, you should exclude module files,
+# since they will be recreated, and may cause churn.  Uncomment if using
+# auto-import.
+# .idea/artifacts
+# .idea/compiler.xml
+# .idea/jarRepositories.xml
+# .idea/modules.xml
+# .idea/*.iml
+# .idea/modules
+# *.iml
+# *.ipr
+
+# CMake
+cmake-build-*/
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# SonarLint plugin
+.idea/sonarlint/
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# Android studio 3.1+ serialized cache file
+.idea/caches/build_file_checksums.ser
+
+### JetBrains+all Patch ###
+# Ignore everything but code style settings and run configurations
+# that are supposed to be shared within teams.
+
+.idea/*
+
+!.idea/codeStyles
+!.idea/runConfigurations
+
+### Rust ###
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+
+### Vim ###
+# Swap
+[._]*.s[a-v][a-z]
+!*.svg  # comment out if you don't need vector files
+[._]*.sw[a-p]
+[._]s[a-rt-v][a-z]
+[._]ss[a-gi-z]
+[._]sw[a-p]
+
+# Session
+Session.vim
+Sessionx.vim
+
+# Temporary
+.netrwhist
+*~
+# Auto-generated tag files
+tags
+# Persistent undo
+[._]*.un~
+
+# End of https://www.toptal.com/developers/gitignore/api/rust,jetbrains+all,vim
+

Cargo.toml

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+[package]
+name = "torrent-rs"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.86"

src/bencode.rs

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+use std::collections::HashMap;
+
+use anyhow::{anyhow, Result};
+
+/*struct FileInfo {
+    length: i64,
+    path: str,
+}
+
+struct TorrentInfo {
+    files: Option<Vec<FileInfo>>,
+    length: Option<i64>,
+    name: str,
+    piece_length: i64,
+    pieces: Vec<str>,
+}
+
+struct Torrent {
+    announce: str,
+    info: TorrentInfo,
+    extra: HashMap<str, str>
+}*/
+
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ByteString(Vec<u8>);
+
+#[derive(Debug, PartialEq)]
+pub enum Bencode {
+    Integer(i64),
+    Bytes(ByteString),
+    List(Vec<Bencode>),
+    Dict(HashMap<ByteString, Bencode>),
+}
+
+#[derive(Debug, PartialEq)]
+enum BencodeType {
+    Integer,
+    Bytes,
+    List,
+    Dict,
+}
+
+impl Bencode {
+    pub fn decode(input: &str) -> Result<Bencode> {
+        Self::decode_slice(input.as_bytes())
+    }
+
+    fn decode_slice(input: &[u8]) -> Result<Bencode>{
+        if input.len() == 0 {
+            return Err(anyhow!("Empty string is not valid bencode"));
+        }
+        let char = input[0] as char;
+        // let type_  = match char {
+        //     'i'  => Ok(Discriminant(Bencode::Integer)),
+        //     'l'  => Ok(Discriminant(Bencode::List)),
+        //     'd'  => Ok(Discriminant(Bencode::Dict)),
+        //     '0'..='9' => Ok(Discriminant(Bencode::Integer)),
+        //     _ => Err(anyhow!("Unknown bencoding char: {char}")),
+        // }?;
+        let type_  = match char {
+            'i'  => Ok(BencodeType::Integer),
+            'l'  => Ok(BencodeType::List),
+            'd'  => Ok(BencodeType::Dict),
+            '0'..='9' => Ok(BencodeType::Bytes),
+            _ => Err(anyhow!("Unknown bencoding char: {char}")),
+        }?;
+        let end_char = match type_ {
+            BencodeType::Integer | BencodeType::List | BencodeType::Dict=> 'e',
+            BencodeType::Bytes => ':'
+        };
+        let mut end_pos = 1;
+        for &c in &input[1..] {
+            if c == end_char as u8 {
+                break
+            }
+            end_pos += 1;
+        }
+        match type_ {
+            BencodeType::Integer => Self::decode_int(&input[1..end_pos]),
+            BencodeType::List => Self::dummy(),
+            BencodeType::Dict => Self::dummy(),
+            BencodeType::Bytes => Self::dummy(),
+        }
+    }
+
+    fn decode_int(input: &[u8]) -> Result<Bencode> {
+        let int_str = std::str::from_utf8(input)?;
+        let int = int_str.parse::<i64>()?;
+        Ok(Bencode::Integer(int))
+    }
+
+    fn dummy() -> Result<Bencode> {
+        Ok(Bencode::Integer(42))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    // Note this useful idiom: importing names from outer (for mod tests) scope.
+    use super::*;
+
+    #[test]
+    fn test_integer() {
+        assert_eq!(Bencode::decode_int("42".as_bytes()).unwrap(), Bencode::Integer(42));
+        assert_eq!(Bencode::decode_int("17".as_bytes()).unwrap(), Bencode::Integer(17));
+        assert_eq!(Bencode::decode_int("-17".as_bytes()).unwrap(), Bencode::Integer(-17));
+    }
+
+    #[test]
+    fn test_integer_str() {
+        assert_eq!(Bencode::decode("i42e").unwrap(), Bencode::Integer(42));
+        assert_eq!(Bencode::decode("i17e").unwrap(), Bencode::Integer(17));
+        assert_eq!(Bencode::decode("i-17e").unwrap(), Bencode::Integer(-17));
+    }
+
+}

src/main.rs

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+mod bencode;
+
+fn main() {
+    println!("Hello, world!");
+}