feat(tun): dns hijack config compatible (#652)

clash/tests/data/config/rules.yaml

@@ -7,13 +7,14 @@ tproxy-port: 8900
 tun:
   enable: true
   device-id: "dev://utun1989"
-  route-all: true
+  route-all: false
   gateway: "198.19.0.1/32"
   so-mark: 3389
   dns-hijack: true
-  # routes:
-  #   - 0.0.0.0/1
-  #   - 128.0.0.0/1
+  # dns-hijack:
+  #   - 1.1.1.1:53
+  routes:
+    - 1.1.1.1/32
 
 ipv6: true
 

clash_lib/src/config/def.rs

@@ -8,6 +8,19 @@ fn default_tun_address() -> String {
     "198.18.0.1/32".to_string()
 }
 
+#[derive(Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum DnsHijack {
+    Switch(bool),
+    List(Vec<String>),
+}
+
+impl Default for DnsHijack {
+    fn default() -> Self {
+        DnsHijack::Switch(false)
+    }
+}
+
 #[derive(Serialize, Deserialize, Default)]
 #[serde(rename_all = "kebab-case")]
 pub struct TunConfig {
@@ -26,8 +39,9 @@ pub struct TunConfig {
     /// policy routing table on Linux only
     pub route_table: Option<u32>,
     /// Will hijack UDP:53 DNS queries to the Clash DNS server if set to true
+    /// setting to a list has the same effect as setting to true
     #[serde(default)]
-    pub dns_hijack: bool,
+    pub dns_hijack: DnsHijack,
 }
 
 #[derive(Serialize, Deserialize, Default, Copy, Clone)]

clash_lib/src/config/internal/config.rs

@@ -122,7 +122,10 @@ impl TryFrom<def::Config> for Config {
                     mtu: t.mtu,
                     so_mark: t.so_mark,
                     route_table: t.route_table,
-                    dns_hijack: t.dns_hijack,
+                    dns_hijack: match t.dns_hijack {
+                        def::DnsHijack::Switch(b) => b,
+                        def::DnsHijack::List(_) => true,
+                    },
                 },
                 None => TunConfig::default(),
             },