Show import key dialog when clicking on WKD URL

This change extends WKD support for direct Web Key Directory URLs
similarily to Facebook key URLs and HKP URLs.

When a link with scheme `https` and path starting with
`/.well-known/openpgpkey/hu/` is clicked Android will suggest importing
the key with OpenKeychain.

Fixes #2270.

OpenKeychain/src/main/AndroidManifest.xml

@@ -719,6 +719,21 @@
                 <data android:pathPattern="/..*/publickey/download" />
             </intent-filter>
 
+            <!-- VIEW from Web Key Directory urls opened in a browser -->
+            <intent-filter android:label="@string/intent_import_key">
+                <action android:name="android.intent.action.VIEW" />
+
+                <category android:name="android.intent.category.BROWSABLE" />
+                <category android:name="android.intent.category.DEFAULT" />
+
+                <data android:scheme="https" />
+
+                <!-- if we don't specify a host, pathPattern will be ignored-->
+                <data android:host="*" />
+
+                <data android:pathPattern="/.well-known/openpgpkey/hu/.*" />
+            </intent-filter>
+
             <!-- IMPORT_KEY with files TODO: does this work? -->
             <intent-filter android:label="@string/intent_import_key">
                 <action android:name="org.sufficientlysecure.keychain.action.IMPORT_KEY" />

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/ImportKeysActivity.java

@@ -56,6 +56,8 @@ public class ImportKeysActivity extends BaseActivity implements ImportKeysListen
     public static final String ACTION_IMPORT_KEY_FROM_KEYSERVER = Constants.IMPORT_KEY_FROM_KEYSERVER;
     public static final String ACTION_IMPORT_KEY_FROM_FACEBOOK
             = Constants.INTENT_PREFIX + "IMPORT_KEY_FROM_FACEBOOK";
+    public static final String ACTION_IMPORT_KEY_FROM_WEB_KEY_DIRECTORY
+            = Constants.INTENT_PREFIX + "ACTION_IMPORT_KEY_FROM_WEB_KEY_DIRECTORY";
     public static final String ACTION_IMPORT_KEY_FROM_KEYSERVER_AND_RETURN_RESULT =
             Constants.INTENT_PREFIX + "IMPORT_KEY_FROM_KEY_SERVER_AND_RETURN_RESULT";
     public static final String ACTION_IMPORT_KEY_FROM_FILE_AND_RETURN = Constants.INTENT_PREFIX
@@ -121,6 +123,8 @@ public class ImportKeysActivity extends BaseActivity implements ImportKeysListen
         if (Intent.ACTION_VIEW.equals(action)) {
             if (FacebookKeyserverClient.isFacebookHost(dataUri)) {
                 action = ACTION_IMPORT_KEY_FROM_FACEBOOK;
+            } else if ("https".equalsIgnoreCase(scheme) || dataUri.getPath().startsWith("/.well-known/openpgpkey/hu/")) {
+                action = ACTION_IMPORT_KEY_FROM_WEB_KEY_DIRECTORY;
             } else if ("http".equalsIgnoreCase(scheme) || "https".equalsIgnoreCase(scheme)) {
                 action = ACTION_SEARCH_KEYSERVER_FROM_URL;
             } else if ("openpgp4fpr".equalsIgnoreCase(scheme)) {
@@ -208,6 +212,13 @@ public class ImportKeysActivity extends BaseActivity implements ImportKeysListen
                 startListFragment(null, null, fbUsername, cloudSearchPrefs);
                 break;
             }
+            case ACTION_IMPORT_KEY_FROM_WEB_KEY_DIRECTORY: {
+                Preferences.CloudSearchPrefs cloudSearchPrefs =
+                        new Preferences.CloudSearchPrefs(false, false, false, true, null);
+                // search immediately
+                startListFragment(null, null, dataUri.toString(), cloudSearchPrefs);
+                break;
+            }
             case ACTION_SEARCH_KEYSERVER_FROM_URL: {
                 // get keyserver from URL
                 HkpKeyserverAddress keyserver = HkpKeyserverAddress.createFromUri(

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/WebKeyDirectoryUtil.java

@@ -24,6 +24,18 @@ public class WebKeyDirectoryUtil {
      */
     @Nullable
     public static URL toWebKeyDirectoryURL(String name) {
+        if (name == null) {
+            return null;
+        }
+
+        if (name.startsWith("https://") && name.contains("/.well-known/openpgpkey/hu/")) {
+            try {
+                return new URL(name);
+            } catch (MalformedURLException e) {
+                return null;
+            }
+        }
+
         Matcher matcher = EMAIL_PATTERN.matcher(name);
 
         if (!matcher.matches()) {

OpenKeychain/src/test/java/org/sufficientlysecure/keychain/util/WebKeyDirectoryUtilTest.java

@@ -27,4 +27,13 @@ public class WebKeyDirectoryUtilTest {
         assertEquals("/.well-known/openpgpkey/hu/4hg7tescnttreaouu4z1izeuuyibwww1", url.getPath());
     }
 
+    @Test
+    public void testWkdDirectUrl() {
+        URL url = WebKeyDirectoryUtil.toWebKeyDirectoryURL("https://openkeychain.org/.well-known/openpgpkey/hu/4hg7tescnttreaouu4z1izeuuyibwww1");
+        assertNotNull(url);
+        assertEquals("openkeychain.org", url.getHost());
+        assertEquals("https", url.getProtocol());
+        assertEquals("/.well-known/openpgpkey/hu/4hg7tescnttreaouu4z1izeuuyibwww1", url.getPath());
+    }
+
 }