Improve WebView spoofing (#3678)

- Spoof `Sec-CH-UA` client hints to match the user agent
- Fix `X-Requested-With` spoofing leaking to unrelated callers
- Update default user agent to Chrome 149

core/common/build.gradle.kts

@@ -41,6 +41,7 @@ dependencies {
     api(libs.kotlinx.serialization.jsonOkio)
 
     api(libs.androidx.preference)
+    implementation(libs.androidx.webkit)
 
     implementation(libs.jsoup)
 

core/common/src/main/kotlin/eu/kanade/tachiyomi/network/NetworkPreferences.kt

@@ -14,6 +14,6 @@ class NetworkPreferences(
 
     val defaultUserAgent: Preference<String> = preferenceStore.getString(
         "default_user_agent",
-        "Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Mobile Safari/537.36",
+        "Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/149.0.0.0 Mobile Safari/537.36",
     )
 }

core/common/src/main/kotlin/eu/kanade/tachiyomi/network/interceptor/WebViewInterceptor.kt

@@ -8,6 +8,7 @@ import android.widget.Toast
 import eu.kanade.tachiyomi.util.system.DeviceUtil
 import eu.kanade.tachiyomi.util.system.WebViewUtil
 import eu.kanade.tachiyomi.util.system.setDefaultSettings
+import eu.kanade.tachiyomi.util.system.setUserAgent
 import eu.kanade.tachiyomi.util.system.toast
 import okhttp3.Headers
 import okhttp3.Interceptor
@@ -84,7 +85,7 @@ abstract class WebViewInterceptor(
         return WebView(context).apply {
             setDefaultSettings()
             // Avoid sending empty User-Agent, Chromium WebView will reset to default if empty
-            settings.userAgentString = request.header("User-Agent") ?: defaultUserAgentProvider()
+            setUserAgent(request.header("User-Agent") ?: defaultUserAgentProvider())
         }
     }
 }

core/common/src/main/kotlin/eu/kanade/tachiyomi/util/system/WebViewUtil.kt

@@ -6,6 +6,9 @@ import android.content.pm.PackageManager
 import android.webkit.CookieManager
 import android.webkit.WebSettings
 import android.webkit.WebView
+import androidx.webkit.UserAgentMetadata
+import androidx.webkit.WebSettingsCompat
+import androidx.webkit.WebViewFeature
 import kotlinx.coroutines.suspendCancellableCoroutine
 import logcat.LogPriority
 import tachiyomi.core.common.util.system.logcat
@@ -99,6 +102,53 @@ fun WebView.setDefaultSettings() {
     CookieManager.getInstance().acceptThirdPartyCookies(this)
 }
 
+/**
+ * Sets the user agent along with the matching user agent metadata, which Chromium uses to populate
+ * the `Sec-CH-UA` client hints. Without this the hints keep advertising the real WebView brand and
+ * version, contradicting the spoofed user agent.
+ */
+fun WebView.setUserAgent(userAgent: String) {
+    settings.userAgentString = userAgent
+
+    if (!WebViewFeature.isFeatureSupported(WebViewFeature.USER_AGENT_METADATA)) return
+
+    val versionMatch = CHROME_VERSION_REGEX.find(userAgent) ?: return
+    val majorVersion = versionMatch.groupValues[1]
+    val fullVersion = majorVersion + versionMatch.groupValues[2].ifEmpty { ".0.0.0" }
+
+    try {
+        val metadata = WebSettingsCompat.getUserAgentMetadata(settings)
+        val brandVersionList = metadata.brandVersionList.map { brandVersion ->
+            val brand = when (brandVersion.brand) {
+                WEBVIEW_BRAND -> CHROME_BRAND
+                CHROMIUM_BRAND -> CHROMIUM_BRAND
+                else -> return@map brandVersion
+            }
+
+            UserAgentMetadata.BrandVersion.Builder()
+                .setBrand(brand)
+                .setMajorVersion(majorVersion)
+                .setFullVersion(fullVersion)
+                .build()
+        }
+
+        WebSettingsCompat.setUserAgentMetadata(
+            settings,
+            UserAgentMetadata.Builder(metadata)
+                .setBrandVersionList(brandVersionList)
+                .setFullVersion(fullVersion)
+                .build(),
+        )
+    } catch (e: Exception) {
+        logcat(LogPriority.ERROR, e) { "Failed to set user agent metadata" }
+    }
+}
+
+private const val WEBVIEW_BRAND = "Android WebView"
+private const val CHROMIUM_BRAND = "Chromium"
+private const val CHROME_BRAND = "Google Chrome"
+private val CHROME_VERSION_REGEX = """Chrome/(\d+)(\.[\d.]+)?""".toRegex()
+
 private fun WebView.getWebViewMajorVersion(): Int {
     val uaRegexMatch = """.*Chrome/(\d+)\..*""".toRegex().matchEntire(getDefaultUserAgentString())
     return if (uaRegexMatch != null && uaRegexMatch.groupValues.size > 1) {