support adding custom mirrors to any existing repo, via "App Repo"

This lets people add any URL as a mirror to an existing repo.  The UX is
people add URLs via any of the normal ways of adding a new repo via Intents,
like clicking URLs, QRCodes, etc.

app/src/main/java/org/fdroid/fdroid/data/DBHelper.java

@@ -88,35 +88,36 @@ public class DBHelper extends SQLiteOpenHelper {
             + RepoTable.Cols.TIMESTAMP + " integer not null default 0, "
             + RepoTable.Cols.ICON + " string, "
             + RepoTable.Cols.MIRRORS + " string, "
+            + RepoTable.Cols.USER_MIRRORS + " string, "
             + RepoTable.Cols.PUSH_REQUESTS + " integer not null default " + Repo.PUSH_REQUEST_IGNORE
             + ");";
 
     static final String CREATE_TABLE_APK =
             "CREATE TABLE " + ApkTable.NAME + " ( "
-            + ApkTable.Cols.APP_ID + " integer not null, "
+                    + ApkTable.Cols.APP_ID + " integer not null, "
-            + ApkTable.Cols.VERSION_NAME + " text not null, "
+                    + ApkTable.Cols.VERSION_NAME + " text not null, "
-            + ApkTable.Cols.REPO_ID + " integer not null, "
+                    + ApkTable.Cols.REPO_ID + " integer not null, "
-            + ApkTable.Cols.HASH + " text not null, "
+                    + ApkTable.Cols.HASH + " text not null, "
-            + ApkTable.Cols.VERSION_CODE + " int not null,"
+                    + ApkTable.Cols.VERSION_CODE + " int not null,"
-            + ApkTable.Cols.NAME + " text not null, "
+                    + ApkTable.Cols.NAME + " text not null, "
-            + ApkTable.Cols.SIZE + " int not null, "
+                    + ApkTable.Cols.SIZE + " int not null, "
-            + ApkTable.Cols.SIGNATURE + " string, "
+                    + ApkTable.Cols.SIGNATURE + " string, "
-            + ApkTable.Cols.SOURCE_NAME + " string, "
+                    + ApkTable.Cols.SOURCE_NAME + " string, "
-            + ApkTable.Cols.MIN_SDK_VERSION + " integer, "
+                    + ApkTable.Cols.MIN_SDK_VERSION + " integer, "
-            + ApkTable.Cols.TARGET_SDK_VERSION + " integer, "
+                    + ApkTable.Cols.TARGET_SDK_VERSION + " integer, "
-            + ApkTable.Cols.MAX_SDK_VERSION + " integer, "
+                    + ApkTable.Cols.MAX_SDK_VERSION + " integer, "
-            + ApkTable.Cols.OBB_MAIN_FILE + " string, "
+                    + ApkTable.Cols.OBB_MAIN_FILE + " string, "
-            + ApkTable.Cols.OBB_MAIN_FILE_SHA256 + " string, "
+                    + ApkTable.Cols.OBB_MAIN_FILE_SHA256 + " string, "
-            + ApkTable.Cols.OBB_PATCH_FILE + " string, "
+                    + ApkTable.Cols.OBB_PATCH_FILE + " string, "
-            + ApkTable.Cols.OBB_PATCH_FILE_SHA256 + " string, "
+                    + ApkTable.Cols.OBB_PATCH_FILE_SHA256 + " string, "
-            + ApkTable.Cols.REQUESTED_PERMISSIONS + " string, "
+                    + ApkTable.Cols.REQUESTED_PERMISSIONS + " string, "
-            + ApkTable.Cols.FEATURES + " string, "
+                    + ApkTable.Cols.FEATURES + " string, "
-            + ApkTable.Cols.NATIVE_CODE + " string, "
+                    + ApkTable.Cols.NATIVE_CODE + " string, "
-            + ApkTable.Cols.HASH_TYPE + " string, "
+                    + ApkTable.Cols.HASH_TYPE + " string, "
-            + ApkTable.Cols.ADDED_DATE + " string, "
+                    + ApkTable.Cols.ADDED_DATE + " string, "
-            + ApkTable.Cols.IS_COMPATIBLE + " int not null, "
+                    + ApkTable.Cols.IS_COMPATIBLE + " int not null, "
-            + ApkTable.Cols.INCOMPATIBLE_REASONS + " text"
+                    + ApkTable.Cols.INCOMPATIBLE_REASONS + " text"
-            + ");";
+                    + ");";
 
     static final String CREATE_TABLE_APP_METADATA = "CREATE TABLE " + AppMetadataTable.NAME
             + " ( "
@@ -181,7 +182,7 @@ public class DBHelper extends SQLiteOpenHelper {
      * app metadata id, because it can instead look through the primary key index. This can be
      * observed by flipping the order of the primary key columns, and noting the resulting sqlite
      * logs along the lines of:
-     *   E/SQLiteLog(14164): (284) automatic index on fdroid_categoryAppMetadataJoin(appMetadataId)
+     * E/SQLiteLog(14164): (284) automatic index on fdroid_categoryAppMetadataJoin(appMetadataId)
      */
     static final String CREATE_TABLE_CAT_JOIN = "CREATE TABLE " + CatJoinTable.NAME
             + " ( "
@@ -214,7 +215,7 @@ public class DBHelper extends SQLiteOpenHelper {
             + "primary key(" + ApkAntiFeatureJoinTable.Cols.APK_ID + ", " + ApkAntiFeatureJoinTable.Cols.ANTI_FEATURE_ID + ") "
             + " );";
 
-    protected static final int DB_VERSION = 77;
+    protected static final int DB_VERSION = 78;
 
     private final Context context;
 
@@ -321,6 +322,17 @@ public class DBHelper extends SQLiteOpenHelper {
         addApkAntiFeatures(db, oldVersion);
         addIgnoreVulnPref(db, oldVersion);
         addLiberapayID(db, oldVersion);
+        addUserMirrorsFields(db, oldVersion);
+    }
+
+    private void addUserMirrorsFields(SQLiteDatabase db, int oldVersion) {
+        if (oldVersion >= 78) {
+            return;
+        }
+        if (!columnExists(db, RepoTable.NAME, RepoTable.Cols.USER_MIRRORS)) {
+            Utils.debugLog(TAG, "Adding " + RepoTable.Cols.USER_MIRRORS + " field to " + RepoTable.NAME + " table in db.");
+            db.execSQL("alter table " + RepoTable.NAME + " add column " + RepoTable.Cols.USER_MIRRORS + " string;");
+        }
     }
 
     private void addLiberapayID(SQLiteDatabase db, int oldVersion) {
@@ -581,7 +593,7 @@ public class DBHelper extends SQLiteOpenHelper {
         updateRepoPriority(db, gpPubKey, gpArchiveAddress, 4);
 
         int priority = 5;
-        String[] projection = new String[] {RepoTable.Cols.SIGNING_CERT, RepoTable.Cols.ADDRESS};
+        String[] projection = new String[]{RepoTable.Cols.SIGNING_CERT, RepoTable.Cols.ADDRESS};
 
         // Order by ID, because that is a good analogy for the order in which they were added.
         // The order in which they were added is likely the order they present in the ManageRepos activity.
@@ -606,7 +618,7 @@ public class DBHelper extends SQLiteOpenHelper {
                 RepoTable.NAME,
                 values,
                 RepoTable.Cols.SIGNING_CERT + " = ? AND " + RepoTable.Cols.ADDRESS + " = ?",
-                new String[] {signingCert, address}
+                new String[]{signingCert, address}
         );
     }
 
@@ -630,15 +642,15 @@ public class DBHelper extends SQLiteOpenHelper {
         Utils.debugLog(TAG, "Migrating app preferences to separate table");
         db.execSQL(
                 "INSERT INTO " + AppPrefsTable.NAME + " ("
-                + AppPrefsTable.Cols.PACKAGE_NAME + ", "
+                        + AppPrefsTable.Cols.PACKAGE_NAME + ", "
-                + AppPrefsTable.Cols.IGNORE_THIS_UPDATE + ", "
+                        + AppPrefsTable.Cols.IGNORE_THIS_UPDATE + ", "
-                + AppPrefsTable.Cols.IGNORE_ALL_UPDATES
+                        + AppPrefsTable.Cols.IGNORE_ALL_UPDATES
-                + ") SELECT "
+                        + ") SELECT "
-                + "id, "
+                        + "id, "
-                + "ignoreThisUpdate, "
+                        + "ignoreThisUpdate, "
-                + "ignoreAllUpdates "
+                        + "ignoreAllUpdates "
-                + "FROM " + AppMetadataTable.NAME + " "
+                        + "FROM " + AppMetadataTable.NAME + " "
-                + "WHERE ignoreThisUpdate > 0 OR ignoreAllUpdates > 0"
+                        + "WHERE ignoreThisUpdate > 0 OR ignoreAllUpdates > 0"
         );
 
         resetTransient(db);
@@ -687,7 +699,7 @@ public class DBHelper extends SQLiteOpenHelper {
 
                 db.execSQL(createTableDdl);
 
-                String nonPackageNameFields = TextUtils.join(", ", new String[] {
+                String nonPackageNameFields = TextUtils.join(", ", new String[]{
                         ApkTable.Cols.APP_ID,
                         ApkTable.Cols.VERSION_NAME,
                         ApkTable.Cols.REPO_ID,
@@ -766,7 +778,7 @@ public class DBHelper extends SQLiteOpenHelper {
         }
         List<Repo> oldrepos = new ArrayList<>();
         Cursor cursor = db.query(RepoTable.NAME,
-                new String[] {RepoTable.Cols.ADDRESS, RepoTable.Cols.IN_USE, RepoTable.Cols.SIGNING_CERT},
+                new String[]{RepoTable.Cols.ADDRESS, RepoTable.Cols.IN_USE, RepoTable.Cols.SIGNING_CERT},
                 null, null, null, null, null);
         if (cursor != null) {
             if (cursor.getCount() > 0) {
@@ -847,7 +859,7 @@ public class DBHelper extends SQLiteOpenHelper {
         }
         List<Repo> oldrepos = new ArrayList<>();
         Cursor cursor = db.query(RepoTable.NAME,
-                new String[] {RepoTable.Cols.ADDRESS, RepoTable.Cols.SIGNING_CERT},
+                new String[]{RepoTable.Cols.ADDRESS, RepoTable.Cols.SIGNING_CERT},
                 null, null, null, null, null);
         if (cursor != null) {
             if (cursor.getCount() > 0) {
@@ -865,7 +877,7 @@ public class DBHelper extends SQLiteOpenHelper {
         for (final Repo repo : oldrepos) {
             ContentValues values = new ContentValues();
             values.put(RepoTable.Cols.FINGERPRINT, Utils.calcFingerprint(repo.signingCertificate));
-            db.update(RepoTable.NAME, values, RepoTable.Cols.ADDRESS + " = ?", new String[] {repo.address});
+            db.update(RepoTable.NAME, values, RepoTable.Cols.ADDRESS + " = ?", new String[]{repo.address});
         }
     }
 
@@ -954,7 +966,7 @@ public class DBHelper extends SQLiteOpenHelper {
 
             db.execSQL(createTableDdl);
 
-            String nonIdFields = TextUtils.join(", ", new String[] {
+            String nonIdFields = TextUtils.join(", ", new String[]{
                     RepoTable.Cols.ADDRESS,
                     RepoTable.Cols.NAME,
                     RepoTable.Cols.DESCRIPTION,
@@ -1235,8 +1247,8 @@ public class DBHelper extends SQLiteOpenHelper {
     }
 
     private static boolean tableExists(SQLiteDatabase db, String table) {
-        Cursor cursor = db.query("sqlite_master", new String[] {"name"},
+        Cursor cursor = db.query("sqlite_master", new String[]{"name"},
-                "type = 'table' AND name = ?", new String[] {table}, null, null, null);
+                "type = 'table' AND name = ?", new String[]{table}, null, null, null);
 
         boolean exists = cursor.getCount() > 0;
         cursor.close();

app/src/main/java/org/fdroid/fdroid/data/Repo.java

@@ -26,13 +26,13 @@ package org.fdroid.fdroid.data;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.text.TextUtils;
-
 import org.fdroid.fdroid.FDroidApp;
 import org.fdroid.fdroid.Utils;
 import org.fdroid.fdroid.data.Schema.RepoTable.Cols;
 
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
@@ -94,6 +94,11 @@ public class Repo extends ValueObject {
     /** Official mirrors of this repo, considered automatically interchangeable */
     public String[] mirrors;
 
+    /**
+     * Mirrors added by the user, either by UI input or by attaching removeable storage
+     */
+    public String[] userMirrors;
+
     /** How to treat push requests included in this repo's index XML */
     public int pushRequests = PUSH_REQUEST_IGNORE;
 
@@ -160,6 +165,9 @@ public class Repo extends ValueObject {
                 case Cols.MIRRORS:
                     mirrors = Utils.parseCommaSeparatedString(cursor.getString(i));
                     break;
+                case Cols.USER_MIRRORS:
+                    userMirrors = Utils.parseCommaSeparatedString(cursor.getString(i));
+                    break;
                 case Cols.PUSH_REQUESTS:
                     pushRequests = cursor.getInt(i);
                     break;
@@ -297,26 +305,43 @@ public class Repo extends ValueObject {
             mirrors = Utils.parseCommaSeparatedString(values.getAsString(Cols.MIRRORS));
         }
 
+        if (values.containsKey(Cols.USER_MIRRORS)) {
+            userMirrors = Utils.parseCommaSeparatedString(values.getAsString(Cols.USER_MIRRORS));
+        }
+
         if (values.containsKey(Cols.PUSH_REQUESTS)) {
             pushRequests = toInt(values.getAsInteger(Cols.PUSH_REQUESTS));
         }
     }
 
     public boolean hasMirrors() {
-        return mirrors != null && mirrors.length > 1;
+        return (mirrors != null && mirrors.length > 1)
+                || (userMirrors != null && userMirrors.length > 0);
     }
 
+    public List<String> getMirrorList() {
+        final ArrayList<String> allMirrors = new ArrayList<String>();
+        if (userMirrors != null) {
+            allMirrors.addAll(Arrays.asList(userMirrors));
+        }
+        if (mirrors != null) {
+            allMirrors.addAll(Arrays.asList(mirrors));
+        }
+        return allMirrors;
+    }
+
+    /**
+     * Get the number of available mirrors, including the canonical repo.
+     */
     public int getMirrorCount() {
         int count = 0;
-        if (mirrors != null && mirrors.length > 1) {
+        for (String m : getMirrorList()) {
-            for (String m: mirrors) {
+            if (!m.equals(address)) {
-                if (!m.equals(address)) {
+                if (FDroidApp.isUsingTor()) {
-                    if (FDroidApp.isUsingTor()) {
+                    count++;
+                } else {
+                    if (!m.contains(".onion")) {
                         count++;
-                    } else {
-                        if (!m.contains(".onion")) {
-                            count++;
-                        }
                     }
                 }
             }
@@ -328,7 +353,7 @@ public class Repo extends ValueObject {
         if (TextUtils.isEmpty(lastWorkingMirror)) {
             lastWorkingMirror = address;
         }
-        List<String> shuffledMirrors = Arrays.asList(mirrors);
+        List<String> shuffledMirrors = getMirrorList();
         Collections.shuffle(shuffledMirrors);
         if (shuffledMirrors.size() > 1) {
             for (String m : shuffledMirrors) {

app/src/main/java/org/fdroid/fdroid/data/Schema.java

@@ -362,12 +362,13 @@ public interface Schema {
             String TIMESTAMP    = "timestamp";
             String ICON         = "icon";
             String MIRRORS      = "mirrors";
+            String USER_MIRRORS = "userMirrors";
             String PUSH_REQUESTS = "pushRequests";
 
             String[] ALL = {
                     _ID, ADDRESS, NAME, DESCRIPTION, IN_USE, PRIORITY, SIGNING_CERT,
                     FINGERPRINT, MAX_AGE, LAST_UPDATED, LAST_ETAG, VERSION, IS_SWAP,
-                    USERNAME, PASSWORD, TIMESTAMP, ICON, MIRRORS, PUSH_REQUESTS,
+                    USERNAME, PASSWORD, TIMESTAMP, ICON, MIRRORS, USER_MIRRORS, PUSH_REQUESTS,
             };
         }
     }

app/src/main/java/org/fdroid/fdroid/views/ManageReposActivity.java

@@ -61,12 +61,15 @@ import org.fdroid.fdroid.data.Repo;
 import org.fdroid.fdroid.data.RepoProvider;
 import org.fdroid.fdroid.data.Schema.RepoTable;
 
+import java.io.File;
 import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.util.Arrays;
+import java.util.HashMap;
 import java.util.Locale;
 
 @SuppressWarnings("LineLength")
@@ -76,7 +79,7 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
     private static final String DEFAULT_NEW_REPO_TEXT = "https://";
 
     private enum AddRepoState {
-        DOESNT_EXIST, EXISTS_FINGERPRINT_MISMATCH, EXISTS_FINGERPRINT_MATCH,
+        DOESNT_EXIST, EXISTS_FINGERPRINT_MISMATCH, EXISTS_ADD_MIRROR,
         EXISTS_DISABLED, EXISTS_ENABLED, EXISTS_UPGRADABLE_TO_SIGNED, INVALID_URL,
         IS_SWAP
     }
@@ -213,18 +216,35 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
     private class AddRepo {
 
         private final Context context;
+        private final HashMap<String, Repo> urlRepoMap = new HashMap<>();
+        private final HashMap<String, Repo> fingerprintRepoMap = new HashMap<>();
         private final AlertDialog addRepoDialog;
-
         private final TextView overwriteMessage;
         private final ColorStateList defaultTextColour;
         private final Button addButton;
 
         private AddRepoState addRepoState;
 
+        /**
+         * Create new instance, setup GUI, and build maps for quickly looking
+         * up repos based on URL or fingerprint.  These need to be in maps
+         * since the user input is validated as they are typing.  This also
+         * checks that the repo type matches, e.g. "repo" or "archive".
+         */
         AddRepo(String newAddress, String newFingerprint, final String username, final String password) {
 
             context = ManageReposActivity.this;
 
+            for (Repo repo : RepoProvider.Helper.all(context)) {
+                urlRepoMap.put(repo.address, repo);
+                for (String url : repo.getMirrorList()) {
+                    urlRepoMap.put(url, repo);
+                }
+                if (TextUtils.equals(getRepoType(newAddress), getRepoType(repo.address))) {
+                    fingerprintRepoMap.put(repo.fingerprint, repo);
+                }
+            }
+
             final View view = getLayoutInflater().inflate(R.layout.addrepo, null);
             addRepoDialog = new AlertDialog.Builder(context).setView(view).create();
             final EditText uriEditText = (EditText) view.findViewById(R.id.edit_uri);
@@ -297,7 +317,7 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
 
                                 case EXISTS_DISABLED:
                                 case EXISTS_UPGRADABLE_TO_SIGNED:
-                                case EXISTS_FINGERPRINT_MATCH:
+                                case EXISTS_ADD_MIRROR:
                                     updateAndEnableExistingRepo(url, fp);
                                     finishedAddingRepo();
                                     break;
@@ -347,9 +367,31 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
             validateRepoDetails(newAddress == null ? "" : newAddress, newFingerprint == null ? "" : newFingerprint);
         }
 
+        /**
+         * Gets the repo type as represented by the final segment of the path. This is
+         * a bit trickier with {@code content://} URLs, since they might have
+         * encoded "/" chars in it, for example:
+         * {@code content://authority/tree/313E-1F1C%3A/document/313E-1F1C%3Aguardianproject.info%2Ffdroid%2Frepo}
+         */
+        private String getRepoType(String url) {
+            String last = Uri.parse(url).getLastPathSegment();
+            if (last == null) {
+                return "";
+            } else {
+                return new File(last).getName();
+            }
+        }
+
         /**
          * Compare the repo and the fingerprint against existing repositories, to see if this
-         * repo matches and display a relevant message to the user if that is the case.
+         * repo matches and display a relevant message to the user if that is the case. There
+         * are many different cases to handle:
+         * <ul>
+         * <li> a signed repo with a {@link Repo#address URL} and fingerprint that matches
+         * <li> a signed repo with a matching fingerprint and URL that matches a mirror
+         * <li> a signed repo with a matching fingerprint, but the URL doesn't match any known mirror
+         * <li>an unsigned repo and no fingerprint was supplied
+         * </ul>
          */
         private void validateRepoDetails(@NonNull String uri, @NonNull String fingerprint) {
 
@@ -361,7 +403,10 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
                 // to the user until they try to save the repo.
             }
 
-            final Repo repo = !TextUtils.isEmpty(uri) ? RepoProvider.Helper.findByAddress(context, uri) : null;
+            Repo repo = fingerprintRepoMap.get(fingerprint);
+            if (repo == null) {
+                repo = urlRepoMap.get(uri);
+            }
 
             if (repo == null) {
                 repoDoesntExist(repo);
@@ -373,9 +418,10 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
                 } else if (repo.fingerprint != null && !repo.fingerprint.equalsIgnoreCase(fingerprint)) {
                     repoFingerprintDoesntMatch(repo);
                 } else {
-                    // Could be either an unsigned repo, and no fingerprint was supplied,
+                    if (!TextUtils.equals(repo.address, uri)
-                    // or it could be a signed repo with a matching fingerprint.
+                            && !repo.getMirrorList().contains(uri)) {
-                    if (repo.inuse) {
+                        repoExistsAddMirror(repo);
+                    } else if (repo.inuse) {
                         repoExistsAndEnabled(repo);
                     } else {
                         repoExistsAndDisabled(repo);
@@ -659,11 +705,34 @@ public class ManageReposActivity extends AppCompatActivity implements LoaderMana
             }
 
             Utils.debugLog(TAG, "Enabling existing repo: " + url);
-            Repo repo = RepoProvider.Helper.findByAddress(context, url);
+            Repo repo = fingerprintRepoMap.get(fingerprint);
+            if (repo == null) {
+                repo = RepoProvider.Helper.findByAddress(context, url);
+            }
+
             ContentValues values = new ContentValues(2);
             values.put(RepoTable.Cols.IN_USE, 1);
             values.put(RepoTable.Cols.FINGERPRINT, fingerprint);
+            if (!TextUtils.equals(url, repo.address)) {
+                boolean addUserMirror = true;
+                for (String mirror : repo.getMirrorList()) {
+                    if (TextUtils.equals(mirror, url)) {
+                        addUserMirror = false;
+                    }
+                }
+                if (addUserMirror) {
+                    if (repo.userMirrors == null) {
+                        repo.userMirrors = new String[]{url};
+                    } else {
+                        int last = repo.userMirrors.length;
+                        repo.userMirrors = Arrays.copyOf(repo.userMirrors, last);
+                        repo.userMirrors[last] = url;
+                    }
+                    values.put(RepoTable.Cols.USER_MIRRORS, Utils.serializeCommaSeparatedString(repo.userMirrors));
+                }
+            }
             RepoProvider.Helper.update(context, repo, values);
+
             notifyDataSetChanged();
             finishedAddingRepo();
         }

app/src/main/java/org/fdroid/fdroid/views/RepoDetailsActivity.java

@@ -109,6 +109,7 @@ public class RepoDetailsActivity extends ActionBarActivity {
                 RepoTable.Cols.ADDRESS,
                 RepoTable.Cols.FINGERPRINT,
                 RepoTable.Cols.MIRRORS,
+                RepoTable.Cols.USER_MIRRORS,
         };
         repo = RepoProvider.Helper.findById(this, repoId, projection);
 
@@ -340,6 +341,19 @@ public class RepoDetailsActivity extends ActionBarActivity {
             }
             officialMirrorsText.setText(builder.toString());
         }
+        if (repo.userMirrors != null) {
+            TextView userMirrorsLabel = (TextView) repoView.findViewById(R.id.label_user_mirrors);
+            userMirrorsLabel.setVisibility(View.VISIBLE);
+            TextView userMirrorsText = (TextView) repoView.findViewById(R.id.text_user_mirrors);
+            userMirrorsText.setVisibility(View.VISIBLE);
+            StringBuilder builder = new StringBuilder();
+            for (String url : repo.userMirrors) {
+                builder.append("◦ ");
+                builder.append(url);
+                builder.append('\n');
+            }
+            userMirrorsText.setText(builder.toString());
+        }
 
         name.setText(repo.name);
 

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

@@ -116,6 +116,7 @@ This often occurs with apps installed via Google Play or other sources, if they
     <string name="no">No</string>
     <string name="repo_add_title">Add new repository</string>
     <string name="repo_add_add">Add</string>
+    <string name="repo_add_mirror">Add mirror</string>
     <string name="links">Links</string>
     <string name="versions">Versions</string>
     <string name="more">More</string>
@@ -138,6 +139,7 @@ This often occurs with apps installed via Google Play or other sources, if they
     <string name="repo_exists_enable">%1$s is already setup, confirm that you want to re-enable it.</string>
     <string name="repo_exists_and_enabled">%1$s is already setup and enabled.</string>
     <string name="repo_delete_to_overwrite">First delete %1$s in order to add this with a conflicting key.</string>
+    <string name="repo_exists_add_mirror">This is a copy of %1$s, add it as a mirror?</string>
     <string name="bad_fingerprint">Bad fingerprint</string>
     <string name="invalid_url">This is not a valid URL.</string>
     <string name="malformed_repo_uri">Ignoring malformed repo URI: %s</string>