fix: validate DNS override on save and free version string

- Add MihomoValidateDns to the bridge (yaml.Unmarshal syntax check),
  exposed as MihomoCore.validateDns; the DNS editor now rejects malformed
  input with an error dialog instead of failing at reconnect.
- Free the Go-allocated string in the nativeVersion JNI wrapper, which
  previously leaked on every call.

Both touch mihomo_jni.cpp, so they share one commit.

Author: HSSkyBoy

app/src/main/cpp/mihomo_jni.cpp

@@ -10,6 +10,7 @@ char* MihomoTraffic();
 char* MihomoProxies();
 int MihomoSelectProxy(char* group, char* name);
 char* MihomoProxyDelay(char* name, char* url, int timeout_ms);
+char* MihomoValidateDns(char* dns_yaml);
 }
 
 extern "C" JNIEXPORT jint JNICALL
@@ -44,7 +45,9 @@ Java_top_uwu_mikubox_core_MihomoCore_nativeLastError(JNIEnv* env, jobject /* thi
 extern "C" JNIEXPORT jstring JNICALL
 Java_top_uwu_mikubox_core_MihomoCore_nativeVersion(JNIEnv* env, jobject /* thiz */) {
     char* version = MihomoVersion();
-    return env->NewStringUTF(version == nullptr ? "unknown" : version);
+    jstring result = env->NewStringUTF(version == nullptr ? "unknown" : version);
+    std::free(version);
+    return result;
 }
 
 extern "C" JNIEXPORT jstring JNICALL
@@ -88,3 +91,14 @@ Java_top_uwu_mikubox_core_MihomoCore_nativeProxyDelay(
     std::free(delay);
     return result;
 }
+
+extern "C" JNIEXPORT jstring JNICALL
+Java_top_uwu_mikubox_core_MihomoCore_nativeValidateDns(
+        JNIEnv* env, jobject /* thiz */, jstring dns_yaml) {
+    const char* dns_chars = env->GetStringUTFChars(dns_yaml, nullptr);
+    char* err = MihomoValidateDns(const_cast<char*>(dns_chars));
+    env->ReleaseStringUTFChars(dns_yaml, dns_chars);
+    jstring result = env->NewStringUTF(err == nullptr ? "" : err);
+    std::free(err);
+    return result;
+}

app/src/main/java/top/uwu/mikubox/core/MihomoCore.kt

@@ -96,6 +96,9 @@ object MihomoCore {
         runCatching { JSONObject(nativeProxyDelay(name, url, timeoutMs)).optInt("delay", -1) }
             .getOrDefault(-1)
 
+    /** Validates a DNS override block; returns null when valid, or an error message. */
+    fun validateDns(yaml: String): String? = nativeValidateDns(yaml).ifBlank { null }
+
     private fun JSONArray?.toStringList(): List<String> =
         if (this == null) emptyList() else List(length()) { optString(it) }
 
@@ -112,4 +115,5 @@ object MihomoCore {
     private external fun nativeProxies(): String
     private external fun nativeSelectProxy(group: String, name: String): Int
     private external fun nativeProxyDelay(name: String, url: String, timeoutMs: Int): String
+    private external fun nativeValidateDns(dnsYaml: String): String
 }

app/src/main/java/top/uwu/mikubox/ui/DnsActivity.kt

@@ -2,7 +2,9 @@ package top.uwu.mikubox.ui
 
 import android.os.Bundle
 import android.widget.Toast
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import top.uwu.mikubox.R
+import top.uwu.mikubox.core.MihomoCore
 import top.uwu.mikubox.core.MihomoDnsSettings
 import top.uwu.mikubox.databinding.ActivityDnsBinding
 
@@ -27,7 +29,17 @@ class DnsActivity : EdgeToEdgeActivity() {
             applyEnabled(checked)
         }
         binding.btnSave.setOnClickListener {
-            MihomoDnsSettings.setYaml(this, binding.etDns.text?.toString().orEmpty())
+            val yaml = binding.etDns.text?.toString().orEmpty()
+            val error = MihomoCore.validateDns(yaml)
+            if (error != null) {
+                MaterialAlertDialogBuilder(this)
+                    .setTitle(R.string.dns_invalid_title)
+                    .setMessage(error)
+                    .setPositiveButton(android.R.string.ok, null)
+                    .show()
+                return@setOnClickListener
+            }
+            MihomoDnsSettings.setYaml(this, yaml)
             toast(R.string.toast_dns_saved)
         }
         binding.btnReset.setOnClickListener {

app/src/main/res/values-zh-rCN/strings.xml

@@ -144,6 +144,7 @@
     <string name="dns_override">覆盖 DNS</string>
     <string name="dns_override_summary">用下方的内容替换每个配置的 dns 部分</string>
     <string name="dns_yaml_hint">DNS（YAML）</string>
+    <string name="dns_invalid_title">DNS 配置无效</string>
     <string name="dns_restart_hint">重新连接以应用更改。</string>
     <string name="action_save">保存</string>
     <string name="action_reset">重置</string>

app/src/main/res/values-zh-rTW/strings.xml

@@ -144,6 +144,7 @@
     <string name="dns_override">覆寫 DNS</string>
     <string name="dns_override_summary">以下方的區塊取代每個設定檔的 dns 區段</string>
     <string name="dns_yaml_hint">DNS（YAML）</string>
+    <string name="dns_invalid_title">DNS 設定無效</string>
     <string name="dns_restart_hint">重新連線以套用變更。</string>
     <string name="action_save">儲存</string>
     <string name="action_reset">重設</string>

app/src/main/res/values/strings.xml

@@ -154,6 +154,7 @@
     <string name="dns_override">Override DNS</string>
     <string name="dns_override_summary">Replace each profile\'s dns section with the block below</string>
     <string name="dns_yaml_hint">DNS (YAML)</string>
+    <string name="dns_invalid_title">Invalid DNS configuration</string>
     <string name="dns_restart_hint">Reconnect to apply changes.</string>
     <string name="action_save">Save</string>
     <string name="action_reset">Reset</string>

core/mihomo-bridge/main.go

@@ -8,6 +8,7 @@ import "C"
 import (
 	"context"
 	"encoding/json"
+	"strings"
 	"sync"
 	"time"
 
@@ -167,6 +168,23 @@ func MihomoProxyDelay(proxyName *C.char, testURL *C.char, timeoutMS C.int) *C.ch
 	return C.CString(string(payload))
 }
 
+// MihomoValidateDns checks that a DNS override block is well-formed YAML that
+// unmarshals to a mapping. Returns an empty string when valid (or blank), or a
+// human-readable error otherwise, so the editor can reject bad input up front.
+//
+//export MihomoValidateDns
+func MihomoValidateDns(dnsYaml *C.char) *C.char {
+	text := strings.TrimSpace(C.GoString(dnsYaml))
+	if text == "" {
+		return C.CString("")
+	}
+	dns := map[string]any{}
+	if err := yaml.Unmarshal([]byte(text), &dns); err != nil {
+		return C.CString(err.Error())
+	}
+	return C.CString("")
+}
+
 func start(configText, homeDir string, tunFD int, dnsOverride string) error {
 	constant.SetHomeDir(homeDir)
 	if err := config.Init(homeDir); err != nil {