Revert "client: Add support for HTTP/HTTPS proxy" (#30979)

Reverts zed-industries/zed#30812

This PR broke nightly builds on linux by adding an OpenSSL dependency to
the `remote_server` binary, which failed to link when building against
musl.

Release Notes:

- N/A

crates/client/src/socks.rs

@@ -0,0 +1,176 @@
+//! socks proxy
+use anyhow::{Context, Result, anyhow};
+use http_client::Url;
+use tokio_socks::tcp::{Socks4Stream, Socks5Stream};
+
+/// Identification to a Socks V4 Proxy
+struct Socks4Identification<'a> {
+    user_id: &'a str,
+}
+
+/// Authorization to a Socks V5 Proxy
+struct Socks5Authorization<'a> {
+    username: &'a str,
+    password: &'a str,
+}
+
+/// Socks Proxy Protocol Version
+///
+/// V4 allows idenfication using a user_id
+/// V5 allows authorization using a username and password
+enum SocksVersion<'a> {
+    V4(Option<Socks4Identification<'a>>),
+    V5(Option<Socks5Authorization<'a>>),
+}
+
+pub(crate) async fn connect_socks_proxy_stream(
+    proxy: &Url,
+    rpc_host: (&str, u16),
+) -> Result<Box<dyn AsyncReadWrite>> {
+    let Some((socks_proxy, version)) = parse_socks_proxy(proxy) else {
+        // If parsing the proxy URL fails, we must avoid falling back to an insecure connection.
+        // SOCKS proxies are often used in contexts where security and privacy are critical,
+        // so any fallback could expose users to significant risks.
+        return Err(anyhow!("Parsing proxy url failed"));
+    };
+
+    // Connect to proxy and wrap protocol later
+    let stream = tokio::net::TcpStream::connect(socks_proxy)
+        .await
+        .context("Failed to connect to socks proxy")?;
+
+    let socks: Box<dyn AsyncReadWrite> = match version {
+        SocksVersion::V4(None) => {
+            let socks = Socks4Stream::connect_with_socket(stream, rpc_host)
+                .await
+                .context("error connecting to socks")?;
+            Box::new(socks)
+        }
+        SocksVersion::V4(Some(Socks4Identification { user_id })) => {
+            let socks = Socks4Stream::connect_with_userid_and_socket(stream, rpc_host, user_id)
+                .await
+                .context("error connecting to socks")?;
+            Box::new(socks)
+        }
+        SocksVersion::V5(None) => {
+            let socks = Socks5Stream::connect_with_socket(stream, rpc_host)
+                .await
+                .context("error connecting to socks")?;
+            Box::new(socks)
+        }
+        SocksVersion::V5(Some(Socks5Authorization { username, password })) => {
+            let socks = Socks5Stream::connect_with_password_and_socket(
+                stream, rpc_host, username, password,
+            )
+            .await
+            .context("error connecting to socks")?;
+            Box::new(socks)
+        }
+    };
+
+    Ok(socks)
+}
+
+fn parse_socks_proxy(proxy: &Url) -> Option<((String, u16), SocksVersion<'_>)> {
+    let scheme = proxy.scheme();
+    let socks_version = if scheme.starts_with("socks4") {
+        let identification = match proxy.username() {
+            "" => None,
+            username => Some(Socks4Identification { user_id: username }),
+        };
+        SocksVersion::V4(identification)
+    } else if scheme.starts_with("socks") {
+        let authorization = proxy.password().map(|password| Socks5Authorization {
+            username: proxy.username(),
+            password,
+        });
+        SocksVersion::V5(authorization)
+    } else {
+        return None;
+    };
+
+    let host = proxy.host()?.to_string();
+    let port = proxy.port_or_known_default()?;
+
+    Some(((host, port), socks_version))
+}
+
+pub(crate) trait AsyncReadWrite:
+    tokio::io::AsyncRead + tokio::io::AsyncWrite + Unpin + Send + 'static
+{
+}
+impl<T: tokio::io::AsyncRead + tokio::io::AsyncWrite + Unpin + Send + 'static> AsyncReadWrite
+    for T
+{
+}
+
+#[cfg(test)]
+mod tests {
+    use url::Url;
+
+    use super::*;
+
+    #[test]
+    fn parse_socks4() {
+        let proxy = Url::parse("socks4://proxy.example.com:1080").unwrap();
+
+        let ((host, port), version) = parse_socks_proxy(&proxy).unwrap();
+        assert_eq!(host, "proxy.example.com");
+        assert_eq!(port, 1080);
+        assert!(matches!(version, SocksVersion::V4(None)))
+    }
+
+    #[test]
+    fn parse_socks4_with_identification() {
+        let proxy = Url::parse("socks4://userid@proxy.example.com:1080").unwrap();
+
+        let ((host, port), version) = parse_socks_proxy(&proxy).unwrap();
+        assert_eq!(host, "proxy.example.com");
+        assert_eq!(port, 1080);
+        assert!(matches!(
+            version,
+            SocksVersion::V4(Some(Socks4Identification { user_id: "userid" }))
+        ))
+    }
+
+    #[test]
+    fn parse_socks5() {
+        let proxy = Url::parse("socks5://proxy.example.com:1080").unwrap();
+
+        let ((host, port), version) = parse_socks_proxy(&proxy).unwrap();
+        assert_eq!(host, "proxy.example.com");
+        assert_eq!(port, 1080);
+        assert!(matches!(version, SocksVersion::V5(None)))
+    }
+
+    #[test]
+    fn parse_socks5_with_authorization() {
+        let proxy = Url::parse("socks5://username:password@proxy.example.com:1080").unwrap();
+
+        let ((host, port), version) = parse_socks_proxy(&proxy).unwrap();
+        assert_eq!(host, "proxy.example.com");
+        assert_eq!(port, 1080);
+        assert!(matches!(
+            version,
+            SocksVersion::V5(Some(Socks5Authorization {
+                username: "username",
+                password: "password"
+            }))
+        ))
+    }
+
+    /// If parsing the proxy URL fails, we must avoid falling back to an insecure connection.
+    /// SOCKS proxies are often used in contexts where security and privacy are critical,
+    /// so any fallback could expose users to significant risks.
+    #[tokio::test]
+    async fn fails_on_bad_proxy() {
+        // Should fail connecting because http is not a valid Socks proxy scheme
+        let proxy = Url::parse("http://localhost:2313").unwrap();
+
+        let result = connect_socks_proxy_stream(&proxy, ("test", 1080)).await;
+        match result {
+            Err(e) => assert_eq!(e.to_string(), "Parsing proxy url failed"),
+            Ok(_) => panic!("Connecting on bad proxy should fail"),
+        };
+    }
+}