feat: Implement SOCKS4/a CONNECT

examples/socks4_basic.yaml

@@ -0,0 +1,14 @@
+- address: 127.0.0.1:50000
+  protocol:
+    type: socks4
+- address: 127.0.0.1:50001
+  protocol:
+    type: socks4
+  rules:
+    # allow connections to all ips
+    mask: 0.0.0.0/0
+    action: allow
+    client_chain:
+      address: 127.0.0.1:50000
+      protocol:
+        type: socks4

src/config/types/client.rs

@@ -327,6 +327,10 @@ pub enum ClientProxyConfig {
         #[serde(default, skip_serializing_if = "Option::is_none")]
         password: Option<String>,
     },
+    Socks4 {
+        #[serde(default, skip_serializing_if = "is_false")]
+        dns_enabled: bool,
+    },
     #[serde(
         alias = "ss",
         deserialize_with = "deserialize_shadowsocks_client",
@@ -448,6 +452,7 @@ impl ClientProxyConfig {
             ClientProxyConfig::Direct => "Direct",
             ClientProxyConfig::Http { .. } => "HTTP",
             ClientProxyConfig::Socks { .. } => "SOCKS5",
+            ClientProxyConfig::Socks4 { .. } => "SOCKS4",
             ClientProxyConfig::Shadowsocks { .. } => "Shadowsocks",
             ClientProxyConfig::Snell { .. } => "Snell",
             ClientProxyConfig::Vless { .. } => "VLESS",
@@ -618,6 +623,17 @@ password: "pass"
         assert!(matches!(result.unwrap(), ClientProxyConfig::Socks { .. }));
     }
 
+    #[test]
+    fn test_client_proxy_config_socks4() {
+        let yaml = r#"
+type: socks4
+dns_enabled: true
+"#;
+        let result: Result<ClientProxyConfig, _> = serde_yaml::from_str(yaml);
+        assert!(result.is_ok());
+        assert!(matches!(result.unwrap(), ClientProxyConfig::Socks4 { .. }));
+    }
+
     #[test]
     fn test_client_proxy_config_http() {
         let yaml = r#"

src/config/types/server.rs

@@ -655,6 +655,12 @@ pub enum ServerProxyConfig {
         #[serde(default = "default_true")]
         udp_enabled: bool,
     },
+    Socks4 {
+        /// Enable DNS functionality (SOCKS4a).
+        /// When false, SOCKS4 returns "request rejected".
+        #[serde(default = "default_true")]
+        dns_enabled: bool,
+    },
     #[serde(
         alias = "ss",
         deserialize_with = "deserialize_shadowsocks_server",
@@ -787,6 +793,7 @@ impl std::fmt::Display for ServerProxyConfig {
         match self {
             Self::Http { .. } => write!(f, "HTTP"),
             Self::Socks { .. } => write!(f, "SOCKS"),
+            Self::Socks4 { .. } => write!(f, "SOCKS4"),
             Self::Shadowsocks { .. } => write!(f, "Shadowsocks"),
             Self::Snell { .. } => write!(f, "Snell"),
             Self::Vless { .. } => write!(f, "Vless"),
@@ -872,6 +879,20 @@ mod tests {
         }
     }
 
+    fn create_test_server_config_socks4() -> ServerConfig {
+        ServerConfig {
+            bind_location: BindLocation::Address(
+                NetLocation::from_ip_addr(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)), 1080).into(),
+            ),
+            protocol: ServerProxyConfig::Socks4 { dns_enabled: false },
+            transport: Transport::Tcp,
+            tcp_settings: None,
+            quic_settings: None,
+            rules: NoneOrSome::None,
+            dns: None,
+        }
+    }
+
     fn create_test_server_config_shadowsocks() -> ServerConfig {
         ServerConfig {
             bind_location: BindLocation::Path(PathBuf::from("/tmp/ss.sock")),
@@ -1123,6 +1144,18 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn test_server_config_socks4() {
+        let original = create_test_server_config_socks4();
+        let yaml_str = serde_yaml::to_string(&original).expect("Failed to serialize");
+        let deserialized: ServerConfig =
+            serde_yaml::from_str(&yaml_str).expect("Failed to deserialize");
+        assert!(matches!(
+            deserialized.protocol,
+            ServerProxyConfig::Socks4 { .. }
+        ));
+    }
+
     #[test]
     fn test_server_config_shadowsocks() {
         let original = create_test_server_config_shadowsocks();

src/lib.rs

@@ -85,6 +85,7 @@ mod shadowsocks;
 mod slide_buffer;
 mod snell;
 mod socket_util;
+mod socks4_handler;
 mod socks5_udp_relay;
 mod socks_handler;
 mod stream_reader;

src/main.rs

@@ -29,6 +29,7 @@ mod shadowsocks;
 mod slide_buffer;
 mod snell;
 mod socket_util;
+mod socks4_handler;
 mod socks5_udp_relay;
 mod socks_handler;
 mod stream_reader;