Reapply "Add LocalNetworkConfig"

This reverts commit 6eea22b18cace5ab7515ad21c2c019605720907d.

Change-Id: I0a2cef4ee992577674c92ecd384dc6f4361afa02
diff --git a/framework/src/android/net/MulticastRoutingConfig.java b/framework/src/android/net/MulticastRoutingConfig.java
new file mode 100644
index 0000000..ebd9fc5
--- /dev/null
+++ b/framework/src/android/net/MulticastRoutingConfig.java
@@ -0,0 +1,264 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import android.annotation.IntDef;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.util.ArraySet;
+import android.util.Log;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.net.Inet6Address;
+import java.net.UnknownHostException;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Set;
+
+/**
+ * A class representing a configuration for multicast routing.
+ *
+ * Internal usage to Connectivity
+ * @hide
+ */
+// TODO : @SystemApi
+public class MulticastRoutingConfig implements Parcelable {
+    private static final String TAG = MulticastRoutingConfig.class.getSimpleName();
+
+    /** Do not forward any multicast packets. */
+    public static final int FORWARD_NONE = 0;
+    /**
+     * Forward only multicast packets with destination in the list of listening addresses.
+     * Ignore the min scope.
+     */
+    public static final int FORWARD_SELECTED = 1;
+    /**
+     * Forward all multicast packets with scope greater or equal than the min scope.
+     * Ignore the list of listening addresses.
+     */
+    public static final int FORWARD_WITH_MIN_SCOPE = 2;
+
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(prefix = { "FORWARD_" }, value = {
+            FORWARD_NONE,
+            FORWARD_SELECTED,
+            FORWARD_WITH_MIN_SCOPE
+    })
+    public @interface MulticastForwardingMode {}
+
+    /**
+     * Not a multicast scope, for configurations that do not use the min scope.
+     */
+    public static final int MULTICAST_SCOPE_NONE = -1;
+
+    public static final MulticastRoutingConfig CONFIG_FORWARD_NONE =
+            new MulticastRoutingConfig(FORWARD_NONE, MULTICAST_SCOPE_NONE, null);
+
+    @MulticastForwardingMode
+    private final int mForwardingMode;
+
+    private final int mMinScope;
+
+    @NonNull
+    private final Set<Inet6Address> mListeningAddresses;
+
+    private MulticastRoutingConfig(@MulticastForwardingMode final int mode, final int scope,
+            @Nullable final Set<Inet6Address> addresses) {
+        mForwardingMode = mode;
+        mMinScope = scope;
+        if (null != addresses) {
+            mListeningAddresses = Collections.unmodifiableSet(new ArraySet<>(addresses));
+        } else {
+            mListeningAddresses = Collections.emptySet();
+        }
+    }
+
+    /**
+     * Returns the forwarding mode.
+     */
+    @MulticastForwardingMode
+    public int getForwardingMode() {
+        return mForwardingMode;
+    }
+
+    /**
+     * Returns the minimal group address scope that is allowed for forwarding.
+     * If the forwarding mode is not FORWARD_WITH_MIN_SCOPE, will be MULTICAST_SCOPE_NONE.
+     */
+    public int getMinScope() {
+        return mMinScope;
+    }
+
+    /**
+     * Returns the list of group addresses listened by the outgoing interface.
+     * The list will be empty if the forwarding mode is not FORWARD_SELECTED.
+     */
+    @NonNull
+    public Set<Inet6Address> getMulticastListeningAddresses() {
+        return mListeningAddresses;
+    }
+
+    private MulticastRoutingConfig(Parcel in) {
+        mForwardingMode = in.readInt();
+        mMinScope = in.readInt();
+        final int count = in.readInt();
+        final ArraySet<Inet6Address> listeningAddresses = new ArraySet<>(count);
+        final byte[] buffer = new byte[16]; // Size of an Inet6Address
+        for (int i = 0; i < count; ++i) {
+            in.readByteArray(buffer);
+            try {
+                listeningAddresses.add((Inet6Address) Inet6Address.getByAddress(buffer));
+            } catch (UnknownHostException e) {
+                Log.wtf(TAG, "Can't read inet6address : " + Arrays.toString(buffer));
+            }
+        }
+        mListeningAddresses = Collections.unmodifiableSet(listeningAddresses);
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeInt(mForwardingMode);
+        dest.writeInt(mMinScope);
+        dest.writeInt(mListeningAddresses.size());
+        for (final Inet6Address addr : mListeningAddresses) {
+            dest.writeByteArray(addr.getAddress());
+        }
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    public static final Creator<MulticastRoutingConfig> CREATOR = new Creator<>() {
+        @Override
+        public MulticastRoutingConfig createFromParcel(Parcel in) {
+            return new MulticastRoutingConfig(in);
+        }
+
+        @Override
+        public MulticastRoutingConfig[] newArray(int size) {
+            return new MulticastRoutingConfig[size];
+        }
+    };
+
+    public static class Builder {
+        @MulticastForwardingMode
+        private final int mForwardingMode;
+        private int mMinScope;
+        private final ArraySet<Inet6Address> mListeningAddresses;
+
+        private Builder(@MulticastForwardingMode final int mode, int scope) {
+            mForwardingMode = mode;
+            mMinScope = scope;
+            mListeningAddresses = new ArraySet<>();
+        }
+
+        /**
+         * Create a builder that forwards nothing.
+         * No properties can be set on such a builder.
+         */
+        public static Builder newBuilderForwardingNone() {
+            return new Builder(FORWARD_NONE, MULTICAST_SCOPE_NONE);
+        }
+
+        /**
+         * Create a builder that forwards packets above a certain scope
+         *
+         * The scope can be changed on this builder, but not the listening addresses.
+         * @param scope the initial scope
+         */
+        public static Builder newBuilderWithMinScope(final int scope) {
+            return new Builder(FORWARD_WITH_MIN_SCOPE, scope);
+        }
+
+        /**
+         * Create a builder that forwards a specified list of listening addresses.
+         *
+         * Addresses can be added and removed from this builder, but the scope can't be set.
+         */
+        public static Builder newBuilderWithListeningAddresses() {
+            return new Builder(FORWARD_SELECTED, MULTICAST_SCOPE_NONE);
+        }
+
+        /**
+         * Sets the minimum scope for this multicast routing config.
+         * This is only meaningful (indeed, allowed) for configs in FORWARD_WITH_MIN_SCOPE mode.
+         * @return this builder
+         */
+        public Builder setMinimumScope(final int scope) {
+            if (FORWARD_WITH_MIN_SCOPE != mForwardingMode) {
+                throw new IllegalArgumentException("Can't set the scope on a builder in mode "
+                        + modeToString(mForwardingMode));
+            }
+            mMinScope = scope;
+            return this;
+        }
+
+        /**
+         * Add an address to the set of listening addresses.
+         *
+         * This is only meaningful (indeed, allowed) for configs in FORWARD_SELECTED mode.
+         * If this address was already added, this is a no-op.
+         * @return this builder
+         */
+        public Builder addListeningAddress(@NonNull final Inet6Address address) {
+            if (FORWARD_SELECTED != mForwardingMode) {
+                throw new IllegalArgumentException("Can't add an address on a builder in mode "
+                        + modeToString(mForwardingMode));
+            }
+            // TODO : should we check that this is a multicast address ?
+            mListeningAddresses.add(address);
+            return this;
+        }
+
+        /**
+         * Remove an address from the set of listening addresses.
+         *
+         * This is only meaningful (indeed, allowed) for configs in FORWARD_SELECTED mode.
+         * If this address was not added, or was already removed, this is a no-op.
+         * @return this builder
+         */
+        public Builder removeListeningAddress(@NonNull final Inet6Address address) {
+            if (FORWARD_SELECTED != mForwardingMode) {
+                throw new IllegalArgumentException("Can't remove an address on a builder in mode "
+                        + modeToString(mForwardingMode));
+            }
+            mListeningAddresses.remove(address);
+            return this;
+        }
+
+        /**
+         * Build the config.
+         */
+        public MulticastRoutingConfig build() {
+            return new MulticastRoutingConfig(mForwardingMode, mMinScope, mListeningAddresses);
+        }
+    }
+
+    private static String modeToString(@MulticastForwardingMode final int mode) {
+        switch (mode) {
+            case FORWARD_NONE: return "FORWARD_NONE";
+            case FORWARD_SELECTED: return "FORWARD_SELECTED";
+            case FORWARD_WITH_MIN_SCOPE: return "FORWARD_WITH_MIN_SCOPE";
+            default: return "unknown multicast routing mode " + mode;
+        }
+    }
+}