Add Shadowsocks upstream support

src/transport/shadowsocks.rs

@@ -0,0 +1,60 @@
+use std::net::{IpAddr, SocketAddr};
+use std::time::Duration;
+
+use shadowsocks::{
+    ProxyClientStream,
+    config::{ServerConfig, ServerType},
+    context::Context,
+    net::ConnectOpts,
+};
+
+use crate::error::{ProxyError, Result};
+
+pub(crate) type ShadowsocksStream = ProxyClientStream<shadowsocks::net::TcpStream>;
+
+fn parse_server_config(url: &str, connect_timeout: Duration) -> Result<ServerConfig> {
+    let mut config = ServerConfig::from_url(url)
+        .map_err(|error| ProxyError::Config(format!("invalid shadowsocks url: {error}")))?;
+
+    if config.plugin().is_some() {
+        return Err(ProxyError::Config(
+            "shadowsocks plugins are not supported".to_string(),
+        ));
+    }
+
+    config.set_timeout(connect_timeout);
+    Ok(config)
+}
+
+pub(crate) fn sanitize_shadowsocks_url(url: &str) -> Result<String> {
+    Ok(parse_server_config(url, Duration::from_secs(1))?
+        .addr()
+        .to_string())
+}
+
+fn connect_opts_for_interface(interface: &Option<String>) -> ConnectOpts {
+    let mut opts = ConnectOpts::default();
+    if let Some(interface) = interface {
+        if let Ok(ip) = interface.parse::<IpAddr>() {
+            opts.bind_local_addr = Some(SocketAddr::new(ip, 0));
+        } else {
+            opts.bind_interface = Some(interface.clone());
+        }
+    }
+    opts
+}
+
+pub(crate) async fn connect_shadowsocks(
+    url: &str,
+    interface: &Option<String>,
+    target: SocketAddr,
+    connect_timeout: Duration,
+) -> Result<ShadowsocksStream> {
+    let config = parse_server_config(url, connect_timeout)?;
+    let context = Context::new_shared(ServerType::Local);
+    let opts = connect_opts_for_interface(interface);
+
+    ProxyClientStream::connect_with_opts(context, &config, target, &opts)
+        .await
+        .map_err(ProxyError::Io)
+}