Merge torrust#651: HTTP Tracker Client: add scrape request

0624bf2 refactor: [torrust#649] use anyhow to handle errors (Jose Celano)
271bfa8 feat: [torrust#649] add cargo dep: anyhow (Jose Celano)
415ca1c feat: [torrust#649] scrape req for the HTTP tracker client (Jose Celano)
b05e2f5 refactor: [torrust#649] use clap in HTTP tracker client (Jose Celano)
f439015 feat: [torrust#649] add cargo dependency: clap (Jose Celano)

Pull request description:

  Usage:

  ```console
  cargo run --bin http_tracker_client scrape https://tracker.torrust-demo.com 9c38422213e30bff212b30c360d26f9a02136422 | jq
  ```

  Response:

  ```json
  {
    "9c38422213e30bff212b30c360d26f9a02136422": {
      "complete": 0,
      "downloaded": 0,
      "incomplete": 1
    }
  }
  ```

ACKs for top commit:
  josecelano:
    ACK 0624bf2

Tree-SHA512: a801824a95e9bae480df452792861ba6e1cac34ade1b53d3ba921865a352bf879a84a5b50ec482d0db0c6f20d4af8a41cc3da7acaa2a403b188287ebc7e97913

Author: josecelano

Cargo.lock

@@ -72,6 +72,8 @@ uuid = { version = "1", features = ["v4"] }
 colored = "2.1.0"
 url = "2.5.0"
 tempfile = "3.9.0"
+clap = { version = "4.4.18", features = ["derive"]}
+anyhow = "1.0.79"
 
 [dev-dependencies]
 criterion = { version = "0.5.1", features = ["async_tokio"] }

Cargo.toml

@@ -1,24 +1,64 @@
-use std::env;
+//! HTTP Tracker client:
+//!
+//! Examples:
+//!
+//! `Announce` request:
+//!
+//! ```text
+//! cargo run --bin http_tracker_client announce http://127.0.0.1:7070 9c38422213e30bff212b30c360d26f9a02136422 | jq
+//! ```
+//!
+//! `Scrape` request:
+//!
+//! ```text
+//! cargo run --bin http_tracker_client scrape http://127.0.0.1:7070 9c38422213e30bff212b30c360d26f9a02136422 | jq
+//! ```
 use std::str::FromStr;
 
+use anyhow::Context;
+use clap::{Parser, Subcommand};
 use reqwest::Url;
 use torrust_tracker::shared::bit_torrent::info_hash::InfoHash;
 use torrust_tracker::shared::bit_torrent::tracker::http::client::requests::announce::QueryBuilder;
 use torrust_tracker::shared::bit_torrent::tracker::http::client::responses::announce::Announce;
-use torrust_tracker::shared::bit_torrent::tracker::http::client::Client;
+use torrust_tracker::shared::bit_torrent::tracker::http::client::responses::scrape;
+use torrust_tracker::shared::bit_torrent::tracker::http::client::{requests, Client};
+
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about = None)]
+struct Args {
+    #[command(subcommand)]
+    command: Command,
+}
+
+#[derive(Subcommand, Debug)]
+enum Command {
+    Announce { tracker_url: String, info_hash: String },
+    Scrape { tracker_url: String, info_hashes: Vec<String> },
+}
 
 #[tokio::main]
-async fn main() {
-    let args: Vec<String> = env::args().collect();
-    if args.len() != 3 {
-        eprintln!("Error: invalid number of arguments!");
-        eprintln!("Usage:   cargo run --bin http_tracker_client <HTTP_TRACKER_URL> <INFO_HASH>");
-        eprintln!("Example: cargo run --bin http_tracker_client https://tracker.torrust-demo.com 9c38422213e30bff212b30c360d26f9a02136422");
-        std::process::exit(1);
+async fn main() -> anyhow::Result<()> {
+    let args = Args::parse();
+
+    match args.command {
+        Command::Announce { tracker_url, info_hash } => {
+            announce_command(tracker_url, info_hash).await?;
+        }
+        Command::Scrape {
+            tracker_url,
+            info_hashes,
+        } => {
+            scrape_command(&tracker_url, &info_hashes).await?;
+        }
     }
+    Ok(())
+}
 
-    let base_url = Url::parse(&args[1]).expect("arg 1 should be a valid HTTP tracker base URL");
-    let info_hash = InfoHash::from_str(&args[2]).expect("arg 2 should be a valid infohash");
+async fn announce_command(tracker_url: String, info_hash: String) -> anyhow::Result<()> {
+    let base_url = Url::parse(&tracker_url).context("failed to parse HTTP tracker base URL")?;
+    let info_hash =
+        InfoHash::from_str(&info_hash).expect("Invalid infohash. Example infohash: `9c38422213e30bff212b30c360d26f9a02136422`");
 
     let response = Client::new(base_url)
         .announce(&QueryBuilder::with_default_values().with_info_hash(&info_hash).query())
@@ -27,9 +67,30 @@ async fn main() {
     let body = response.bytes().await.unwrap();
 
     let announce_response: Announce = serde_bencode::from_bytes(&body)
-        .unwrap_or_else(|_| panic!("response body should be a valid announce response, got \"{:#?}\"", &body));
+        .unwrap_or_else(|_| panic!("response body should be a valid announce response, got: \"{:#?}\"", &body));
+
+    let json = serde_json::to_string(&announce_response).context("failed to serialize scrape response into JSON")?;
+
+    println!("{json}");
+
+    Ok(())
+}
+
+async fn scrape_command(tracker_url: &str, info_hashes: &[String]) -> anyhow::Result<()> {
+    let base_url = Url::parse(tracker_url).context("failed to parse HTTP tracker base URL")?;
+
+    let query = requests::scrape::Query::try_from(info_hashes).context("failed to parse infohashes")?;
+
+    let response = Client::new(base_url).scrape(&query).await;
+
+    let body = response.bytes().await.unwrap();
+
+    let scrape_response = scrape::Response::try_from_bencoded(&body)
+        .unwrap_or_else(|_| panic!("response body should be a valid scrape response, got: \"{:#?}\"", &body));
+
+    let json = serde_json::to_string(&scrape_response).context("failed to serialize scrape response into JSON")?;
 
-    let json = serde_json::to_string(&announce_response).expect("announce response should be a valid JSON");
+    println!("{json}");
 
-    print!("{json}");
+    Ok(())
 }

src/bin/http_tracker_client.rs

@@ -1,4 +1,6 @@
-use std::fmt;
+use std::convert::TryFrom;
+use std::error::Error;
+use std::fmt::{self};
 use std::str::FromStr;
 
 use crate::shared::bit_torrent::info_hash::InfoHash;
@@ -14,6 +16,35 @@ impl fmt::Display for Query {
     }
 }
 
+#[derive(Debug)]
+#[allow(dead_code)]
+pub struct ConversionError(String);
+
+impl fmt::Display for ConversionError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Invalid infohash: {}", self.0)
+    }
+}
+
+impl Error for ConversionError {}
+
+impl TryFrom<&[String]> for Query {
+    type Error = ConversionError;
+
+    fn try_from(info_hashes: &[String]) -> Result<Self, Self::Error> {
+        let mut validated_info_hashes: Vec<ByteArray20> = Vec::new();
+
+        for info_hash in info_hashes {
+            let validated_info_hash = InfoHash::from_str(info_hash).map_err(|_| ConversionError(info_hash.clone()))?;
+            validated_info_hashes.push(validated_info_hash.0);
+        }
+
+        Ok(Self {
+            info_hash: validated_info_hashes,
+        })
+    }
+}
+
 /// HTTP Tracker Scrape Request:
 ///
 /// <https://www.bittorrent.org/beps/bep_0048.html>

src/shared/bit_torrent/tracker/http/client/requests/scrape.rs

@@ -1,12 +1,14 @@
 use std::collections::HashMap;
+use std::fmt::Write;
 use std::str;
 
-use serde::{self, Deserialize, Serialize};
+use serde::ser::SerializeMap;
+use serde::{self, Deserialize, Serialize, Serializer};
 use serde_bencode::value::Value;
 
 use crate::shared::bit_torrent::tracker::http::{ByteArray20, InfoHash};
 
-#[derive(Debug, PartialEq, Default)]
+#[derive(Debug, PartialEq, Default, Deserialize)]
 pub struct Response {
     pub files: HashMap<ByteArray20, File>,
 }
@@ -60,6 +62,31 @@ struct DeserializedResponse {
     pub files: Value,
 }
 
+// Custom serialization for Response
+impl Serialize for Response {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut map = serializer.serialize_map(Some(self.files.len()))?;
+        for (key, value) in &self.files {
+            // Convert ByteArray20 key to hex string
+            let hex_key = byte_array_to_hex_string(key);
+            map.serialize_entry(&hex_key, value)?;
+        }
+        map.end()
+    }
+}
+
+// Helper function to convert ByteArray20 to hex string
+fn byte_array_to_hex_string(byte_array: &ByteArray20) -> String {
+    let mut hex_string = String::with_capacity(byte_array.len() * 2);
+    for byte in byte_array {
+        write!(hex_string, "{byte:02x}").expect("Writing to string should never fail");
+    }
+    hex_string
+}
+
 #[derive(Default)]
 pub struct ResponseBuilder {
     response: Response,