fix(torad): bypass system proxy env vars when fetching .torrent sources

reqwest honours HTTP_PROXY/ALL_PROXY from the environment by default. A
self-hosted Jackett is normally reached over loopback, and routing
loopback through an inherited proxy breaks it — which matters once torad
runs in an environment where those vars are set for VPN reasons.

Extracts the builder into `build_http_client` so the behaviour is
directly testable, and adds a test that serves one response from a
loopback listener while ALL_PROXY points at a dead port. The test is
falsifiable: removing .no_proxy() makes it fail with ConnectionRefused
against the proxy address, which was verified before committing.

The proxy URL is deliberately http:// rather than socks5:// — reqwest is
built here without its `socks` feature, so a SOCKS proxy would be ignored
and the test would pass either way.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

crates/torad/src/source/mod.rs

@@ -48,15 +48,29 @@ pub(crate) struct SourceResolver {
     handlers: Vec<Box<dyn SourceHandler>>,
 }
 
+/// Builds the HTTP client shared by the Jackett and generic-`.torrent` handlers.
+///
+/// Two non-default settings, both load-bearing:
+///
+/// - **Manual redirect policy.** Jackett 302-redirects to `magnet:` URIs that
+///   reqwest refuses to follow; we inspect `Location` ourselves so the magnet
+///   handler can take over.
+/// - **No system proxy.** reqwest otherwise honours `HTTP_PROXY`/`ALL_PROXY`
+///   from the environment. A self-hosted Jackett is typically reached over
+///   loopback, and routing loopback through an inherited proxy breaks it. Note
+///   this client also serves arbitrary remote `.torrent` URLs via
+///   [`http_torrent`], so the setting applies to those too.
+fn build_http_client() -> Result<reqwest::Client> {
+    reqwest::Client::builder()
+        .redirect(reqwest::redirect::Policy::none())
+        .no_proxy()
+        .build()
+        .context("failed to build HTTP client")
+}
+
 impl SourceResolver {
     pub(crate) fn new() -> Result<Self> {
-        // Manual redirect policy: Jackett 302-redirects to `magnet:` URIs that
-        // reqwest would refuse to follow; we want to inspect `Location`
-        // ourselves so the magnet handler can take over.
-        let http_client = reqwest::Client::builder()
-            .redirect(reqwest::redirect::Policy::none())
-            .build()
-            .context("failed to build HTTP client")?;
+        let http_client = build_http_client()?;
         Ok(Self {
             handlers: vec![
                 Box::new(magnet::MagnetHandler),
@@ -76,3 +90,59 @@ impl SourceResolver {
         anyhow::bail!("no handler matched source: {source}")
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    use tokio::net::TcpListener;
+
+    /// Serves exactly one minimal HTTP/1.1 response, then stops. Returns the
+    /// bound address so the test can build a URL for it.
+    async fn spawn_oneshot_server() -> std::net::SocketAddr {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let addr = listener.local_addr().unwrap();
+        tokio::spawn(async move {
+            if let Ok((mut sock, _)) = listener.accept().await {
+                let mut buf = [0u8; 1024];
+                let _ = sock.read(&mut buf).await;
+                let _ = sock
+                    .write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 2\r\n\r\nhi")
+                    .await;
+                let _ = sock.flush().await;
+            }
+        });
+        addr
+    }
+
+    /// Regression for [`build_http_client`]'s `.no_proxy()`: reqwest reads
+    /// `ALL_PROXY` at build time, so without it this request would be sent to a
+    /// dead proxy instead of the loopback server and fail.
+    ///
+    /// The proxy URL is deliberately `http://`, not `socks5://` — reqwest is
+    /// built here without its `socks` feature, so a SOCKS proxy would simply be
+    /// ignored and the test would pass with or without `.no_proxy()`.
+    ///
+    /// Env vars are process-global and `set_var` is `unsafe` under the 2024
+    /// edition. This is the only test in the crate that touches the
+    /// environment, and it restores it before yielding, so nothing else here
+    /// can observe the change — but it is not safe to add a second such test
+    /// without serialising them.
+    #[tokio::test]
+    async fn http_client_ignores_system_proxy() {
+        let addr = spawn_oneshot_server().await;
+
+        unsafe { std::env::set_var("ALL_PROXY", "http://127.0.0.1:1") };
+        let client = build_http_client();
+        unsafe { std::env::remove_var("ALL_PROXY") };
+
+        let response = client
+            .expect("client should build")
+            .get(format!("http://{addr}/"))
+            .send()
+            .await
+            .expect("request must reach the loopback server, not the dead proxy");
+        assert_eq!(response.status(), reqwest::StatusCode::OK);
+        assert_eq!(response.text().await.unwrap(), "hi");
+    }
+}