Add embed_session_info option for Android per-app routing

- Add `embed_session_info` boolean field to Args struct with CLI argument
- Add `runWithSessionInfo` JNI method in android.rs accepting embed_session_info parameter
- Pass embed_session_info flag through SocksProxyManager and SocksProxyImpl constructors
- Modify SOCKS5 authentication to embed session info in username field when enabled
- Format embedded username as "original_username|protocol|src_ip|src_port"
- Enable per-app routing on Android

src/android.rs

@@ -58,6 +58,58 @@ pub unsafe extern "C" fn Java_com_github_shadowsocks_bg_Tun2proxy_run(
     .resolve::<jni::errors::LogErrorAndDefault>()
 }
 
+/// # Safety
+///
+/// Running tun2proxy with some arguments including embed_session_info option
+/// Parameters:
+/// - proxy_url: the proxy url, e.g. "socks5://user:[email protected]:1080"
+/// - tun_fd: the tun file descriptor, it will be owned by tun2proxy
+/// - close_fd_on_drop: whether close the tun_fd on drop
+/// - tun_mtu: the tun mtu
+/// - dns_strategy: the dns strategy, see ArgDns enum
+/// - verbosity: the verbosity level, see ArgVerbosity enum
+/// - embed_session_info: if true, embeds session info in SOCKS5 username field
+///   Format: "original_username|protocol|src_ip|src_port"
+///   Use this with getConnectionOwnerUid() for per-app routing on Android 10+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn Java_com_github_shadowsocks_bg_Tun2proxy_runWithSessionInfo(
+    mut env: EnvUnowned<'_>,
+    _clazz: JClass<'_>,
+    proxy_url: JString<'_>,
+    tun_fd: jint,
+    close_fd_on_drop: jboolean,
+    tun_mtu: jchar,
+    verbosity: jint,
+    dns_strategy: jint,
+    embed_session_info: jboolean,
+) -> jint {
+    let dns = dns_strategy.try_into().unwrap();
+    let verbosity = verbosity.try_into().unwrap();
+    let filter_str = &format!("off,tun2proxy={verbosity}");
+    let filter = android_logger::FilterBuilder::new().parse(filter_str).build();
+    android_logger::init_once(
+        android_logger::Config::default()
+            .with_tag("tun2proxy")
+            .with_max_level(log::LevelFilter::Trace)
+            .with_filter(filter),
+    );
+    env.with_env(|env: &mut Env| -> Result<jint> {
+        let proxy_url = get_java_string(env, &proxy_url).unwrap();
+        let proxy = ArgProxy::try_from(proxy_url.as_str()).unwrap();
+
+        let mut args = Args::default();
+        args.proxy(proxy)
+            .tun_fd(Some(tun_fd))
+            .close_fd_on_drop(close_fd_on_drop)
+            .dns(dns)
+            .verbosity(verbosity)
+            .embed_session_info(embed_session_info != 0);
+        let v = crate::general_api::general_run_for_api(args, tun_mtu, false);
+        Ok::<jint, Error>(v)
+    })
+    .resolve::<jni::errors::LogErrorAndDefault>()
+}
+
 /// # Safety
 ///
 /// Shutdown tun2proxy

src/args.rs

@@ -128,6 +128,12 @@ pub struct Args {
     #[arg(long, value_name = "number", default_value = "200")]
     pub max_sessions: usize,
 
+    /// Embed session info (protocol, src_ip, src_port) in SOCKS5 username field.
+    /// Format: "original_username|protocol|src_ip|src_port"
+    /// Useful for per-app routing on Android via getConnectionOwnerUid().
+    #[arg(long)]
+    pub embed_session_info: bool,
+
     /// UDP gateway server address, forwards UDP packets via specified TCP server
     #[cfg(feature = "udpgw")]
     #[arg(long, value_name = "IP:PORT")]
@@ -188,6 +194,7 @@ impl Default for Args {
             daemonize: false,
             exit_on_fatal_error: false,
             max_sessions: 200,
+            embed_session_info: false,
             #[cfg(feature = "udpgw")]
             udpgw_server: None,
             #[cfg(feature = "udpgw")]
@@ -273,6 +280,11 @@ impl Args {
         self.setup = setup;
         self
     }
+
+    pub fn embed_session_info(&mut self, embed_session_info: bool) -> &mut Self {
+        self.embed_session_info = embed_session_info;
+        self
+    }
 }
 
 #[repr(C)]

src/lib.rs

@@ -225,9 +225,10 @@ where
     let socket_queue = None;
 
     use socks5_impl::protocol::Version::{V4, V5};
+    let embed_session_info = args.embed_session_info;
     let mgr: Arc<dyn ProxyHandlerManager> = match args.proxy.proxy_type {
-        ProxyType::Socks5 => Arc::new(SocksProxyManager::new(server_addr, V5, key)),
+        ProxyType::Socks5 => Arc::new(SocksProxyManager::new(server_addr, V5, key, embed_session_info)),
-        ProxyType::Socks4 => Arc::new(SocksProxyManager::new(server_addr, V4, key)),
+        ProxyType::Socks4 => Arc::new(SocksProxyManager::new(server_addr, V4, key, embed_session_info)),
         ProxyType::Http => Arc::new(HttpManager::new(server_addr, key)),
         ProxyType::None => Arc::new(NoProxyManager::new()),
     };

src/socks.rs

@@ -32,6 +32,7 @@ struct SocksProxyImpl {
     credentials: Option<UserKey>,
     command: protocol::Command,
     udp_associate: Option<SocketAddr>,
+    embed_session_info: bool,
 }
 
 impl SocksProxyImpl {
@@ -42,6 +43,7 @@ impl SocksProxyImpl {
         credentials: Option<UserKey>,
         version: Version,
         command: protocol::Command,
+        embed_session_info: bool,
     ) -> Result<Self> {
         let mut result = Self {
             server_addr,
@@ -56,6 +58,7 @@ impl SocksProxyImpl {
             credentials,
             command,
             udp_associate: None,
+            embed_session_info,
         };
         result.send_client_hello()?;
         Ok(result)
@@ -170,7 +173,19 @@ impl SocksProxyImpl {
     fn send_auth_data(&mut self) -> std::io::Result<()> {
         let tmp = UserKey::default();
         let credentials = self.credentials.as_ref().unwrap_or(&tmp);
-        let request = password_method::Request::new(&credentials.username, &credentials.password);
+        
+        let username = if self.embed_session_info {
+            let proto = match self.command {
+                protocol::Command::Connect => "tcp",
+                protocol::Command::UdpAssociate => "udp",
+                _ => "unknown",
+            };
+            format!("{}|{}|{}|{}", credentials.username, proto, self.info.src.ip(), self.info.src.port())
+        } else {
+            credentials.username.clone()
+        };
+        
+        let request = password_method::Request::new(&username, &credentials.password);
         request.write_to_stream(&mut self.server_outbuf)?;
         self.state = SocksState::ReceiveAuthResponse;
         Ok(())
@@ -332,6 +347,7 @@ pub(crate) struct SocksProxyManager {
     server: SocketAddr,
     credentials: Option<UserKey>,
     version: Version,
+    embed_session_info: bool,
 }
 
 #[async_trait::async_trait]
@@ -352,16 +368,18 @@ impl ProxyHandlerManager for SocksProxyManager {
             credentials,
             self.version,
             command,
+            self.embed_session_info,
         )?)))
     }
 }
 
 impl SocksProxyManager {
-    pub(crate) fn new(server: SocketAddr, version: Version, credentials: Option<UserKey>) -> Self {
+    pub(crate) fn new(server: SocketAddr, version: Version, credentials: Option<UserKey>, embed_session_info: bool) -> Self {
         Self {
             server,
             credentials,
             version,
+            embed_session_info,
         }
     }
 }