Proxy configurators

src/org/adblockplus/android/configurators/ProxyConfigurators.java

+/*
+ * This file is part of Adblock Plus <http://adblockplus.org/>,
+ * Copyright (C) 2006-2014 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.adblockplus.android.configurators;
+
+import java.lang.reflect.Constructor;
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.HashMap;
+
+import org.adblockplus.android.Utils;
+
+import android.content.Context;
+import android.util.Log;
+
+/**
+ * Common proxy configurator methods.
+ */
+public final class ProxyConfigurators
+{
+  private static final String TAG = Utils.getTag(ProxyConfigurators.class);
+  private static final ArrayList<Class<?>> CONFIGURATORS = new ArrayList<Class<?>>();
+  private static final HashMap<ProxyRegistrationType, Class<?>> CONFIGURATOR_MAP = new HashMap<ProxyRegistrationType, Class<?>>();
+  private static final HashMap<Class<?>, ProxyRegistrationType> CONFIGURATOR_INV_MAP = new HashMap<Class<?>, ProxyRegistrationType>();
+
+  static
+  {
+    /*
+     * Add new proxy-configurators here.
+     *
+     * Note: order of adding is important (as later added configurators act as fallbacks for earlier ones).
+     */
+    add(CyanogenProxyConfigurator.class);
+    add(IptablesProxyConfigurator.class);
+    add(NativeProxyConfigurator.class);
+    add(ManualProxyConfigurator.class);
+  }
+
+  private ProxyConfigurators()
+  {
+    // no instantiation
+  }
+
+  private static void add(final Class<?> clazz)
+  {
+    try
+    {
+      final Constructor<?> ctor = clazz.getConstructor(Context.class);
+      final ProxyConfigurator pc = (ProxyConfigurator) ctor.newInstance((Context) null);
+      final ProxyRegistrationType type = pc.getType();
+
+      if (!CONFIGURATOR_MAP.containsKey(type))
+      {
+        CONFIGURATORS.add(clazz);
+        CONFIGURATOR_MAP.put(type, clazz);
+        CONFIGURATOR_INV_MAP.put(clazz, type);
+      }
+      else
+      {
+        // We fail hard here.
+        throw new IllegalArgumentException("Duplicate proxy configurator (" + clazz + ") for type: " + type);
+      }
+    }
+    catch (final Exception e)
+    {
+      // We fail hard here.
+      throw new IllegalStateException("Failed to register proxy configurator (" + clazz + ")", e);
+    }
+  }
+
+  private static ProxyConfigurator initialize(final Context context, final ProxyConfigurator from)
+  {
+    int i = 0;
+
+    if (from != null)
+    {
+      // Scan through configurators to find last used one
+      while (i < CONFIGURATORS.size() && !CONFIGURATORS.get(i).equals(from.getClass()))
+      {
+        i++;
+      }
+      // One after last-used
+      i++;
+    }
+
+    // Loop through configurators until one succeeds to initialize
+    while (i < CONFIGURATORS.size())
+    {
+      try
+      {
+        final Class<?> clazz = CONFIGURATORS.get(i);
+        final Constructor<?> ctor = clazz.getConstructor(Context.class);
+        final ProxyConfigurator pc = (ProxyConfigurator) ctor.newInstance(context);
+        if (pc.initialize())
+        {
+          return pc;
+        }
+      }
+      catch (final Exception e)
+      {
+        Log.d(TAG, "Configurator exception", e);
+        // We don't need to handle exceptions here, only success matters
+      }
+
+      i++;
+    }
+
+    return null;
+  }
+
+  public static ProxyConfigurator registerProxy(final Context context, final InetAddress address, final int port)
+  {
+    ProxyConfigurator pc = null;
+
+    do
+    {
+      pc = initialize(context, pc);
+
+      if (pc != null)
+      {
+        if (pc.registerProxy(address, port))
+        {
+          Log.d(TAG, "Using '" + pc.toString() + "'");
+          return pc;
+        }
+
+        pc.shutdown();
+      }
+    }
+    while (pc != null);
+
+    return null;
+  }
+}