fix: sanitize DNS preference inputs

Author: hawkff

app/src/main/java/io/nekohasekai/sagernet/fmt/ConfigBuilder.kt

@@ -47,6 +47,10 @@ import moe.matsuri.nb4a.utils.Util
 import moe.matsuri.nb4a.utils.listByLineOrComma
 import okhttp3.HttpUrl.Companion.toHttpUrlOrNull
 
+private fun sanitizeDnsEntry(value: String): String {
+    return value.filterNot { it.isISOControl() }.trim()
+}
+
 const val TAG_MIXED = "mixed-in"
 
 const val TAG_PROXY = "proxy"
@@ -144,9 +148,9 @@ fun buildConfig(
     val isVPN = DataStore.serviceMode == Key.MODE_VPN
     val bind = if (!forTest && DataStore.allowAccess) "0.0.0.0" else LOCALHOST
     val remoteDns = DataStore.remoteDns.split("\n")
-        .mapNotNull { dns -> dns.trim().takeIf { it.isNotBlank() && !it.startsWith("#") } }
+        .mapNotNull { dns -> sanitizeDnsEntry(dns).takeIf { it.isNotBlank() && !it.startsWith("#") } }
     val directDNS = DataStore.directDns.split("\n")
-        .mapNotNull { dns -> dns.trim().takeIf { it.isNotBlank() && !it.startsWith("#") } }
+        .mapNotNull { dns -> sanitizeDnsEntry(dns).takeIf { it.isNotBlank() && !it.startsWith("#") } }
     val enableDnsRouting = DataStore.enableDnsRouting
     val useFakeDns = DataStore.enableFakeDns && !forTest
     val needSniff = DataStore.trafficSniffing > 0

app/src/main/java/io/nekohasekai/sagernet/ui/SettingsPreferenceFragment.kt

@@ -41,6 +41,26 @@ class SettingsPreferenceFragment : PreferenceFragmentCompat() {
         true
     }
 
+    private fun sanitizeDnsPreferenceValue(value: String): String {
+        return value.lines().joinToString("\n") { line ->
+            line.filterNot { it.isISOControl() }.trim()
+        }
+    }
+
+    private fun dnsReloadListener(preference: Preference, newValue: Any?): Boolean {
+        val rawValue = newValue as? String ?: return reloadListener.onPreferenceChange(preference, newValue)
+        val sanitizedValue = sanitizeDnsPreferenceValue(rawValue)
+        if (sanitizedValue != rawValue) {
+            if (preference is EditTextPreference) {
+                preference.text = sanitizedValue
+            }
+            needReload()
+            return false
+        }
+        needReload()
+        return true
+    }
+
     override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
         preferenceManager.preferenceDataStore = DataStore.configurationStore
         DataStore.initGlobal()
@@ -203,8 +223,12 @@ class SettingsPreferenceFragment : PreferenceFragmentCompat() {
         concurrentDial.onPreferenceChangeListener = reloadListener
 
         enableFakeDns.onPreferenceChangeListener = reloadListener
-        remoteDns.onPreferenceChangeListener = reloadListener
-        directDns.onPreferenceChangeListener = reloadListener
+        remoteDns.onPreferenceChangeListener = Preference.OnPreferenceChangeListener { preference, newValue ->
+            dnsReloadListener(preference, newValue)
+        }
+        directDns.onPreferenceChangeListener = Preference.OnPreferenceChangeListener { preference, newValue ->
+            dnsReloadListener(preference, newValue)
+        }
         enableDnsRouting.onPreferenceChangeListener = reloadListener
 
         ipv6Mode.onPreferenceChangeListener = reloadListener