340 lines
15 KiB
Java
340 lines
15 KiB
Java
/*
|
||
* Copyright (C) 2020 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.IntRange;
|
||
import android.annotation.NonNull;
|
||
import android.annotation.Nullable;
|
||
import android.annotation.RequiresPermission;
|
||
import android.annotation.SystemApi;
|
||
import android.content.Context;
|
||
import android.os.Handler;
|
||
import android.os.Looper;
|
||
import android.os.Message;
|
||
import android.os.Messenger;
|
||
import android.util.Log;
|
||
|
||
import com.android.internal.annotations.GuardedBy;
|
||
|
||
import java.util.ArrayList;
|
||
import java.util.concurrent.Executor;
|
||
|
||
/**
|
||
* Base class for network providers such as telephony or Wi-Fi. NetworkProviders connect the device
|
||
* to networks and makes them available to the core network stack by creating
|
||
* {@link NetworkAgent}s. The networks can then provide connectivity to apps and can be interacted
|
||
* with via networking APIs such as {@link ConnectivityManager}.
|
||
*
|
||
* Subclasses should implement {@link #onNetworkRequested} and {@link #onNetworkRequestWithdrawn}
|
||
* to receive {@link NetworkRequest}s sent by the system and by apps. A network that is not the
|
||
* best (highest-scoring) network for any request is generally not used by the system, and torn
|
||
* down.
|
||
*
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
public class NetworkProvider {
|
||
/**
|
||
* {@code providerId} value that indicates the absence of a provider. It is the providerId of
|
||
* any NetworkProvider that is not currently registered, and of any NetworkRequest that is not
|
||
* currently being satisfied by a network.
|
||
*/
|
||
public static final int ID_NONE = -1;
|
||
|
||
/**
|
||
* The first providerId value that will be allocated.
|
||
* @hide only used by ConnectivityService.
|
||
*/
|
||
public static final int FIRST_PROVIDER_ID = 1;
|
||
|
||
/** @hide only used by ConnectivityService */
|
||
public static final int CMD_REQUEST_NETWORK = 1;
|
||
/** @hide only used by ConnectivityService */
|
||
public static final int CMD_CANCEL_REQUEST = 2;
|
||
|
||
private final Messenger mMessenger;
|
||
private final String mName;
|
||
private final Context mContext;
|
||
|
||
private int mProviderId = ID_NONE;
|
||
|
||
/**
|
||
* Constructs a new NetworkProvider.
|
||
*
|
||
* @param looper the Looper on which to run {@link #onNetworkRequested} and
|
||
* {@link #onNetworkRequestWithdrawn}.
|
||
* @param name the name of the listener, used only for debugging.
|
||
*
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
public NetworkProvider(@NonNull Context context, @NonNull Looper looper, @NonNull String name) {
|
||
// TODO (b/174636568) : this class should be able to cache an instance of
|
||
// ConnectivityManager so it doesn't have to fetch it again every time.
|
||
final Handler handler = new Handler(looper) {
|
||
@Override
|
||
public void handleMessage(Message m) {
|
||
switch (m.what) {
|
||
case CMD_REQUEST_NETWORK:
|
||
onNetworkRequested((NetworkRequest) m.obj, m.arg1, m.arg2);
|
||
break;
|
||
case CMD_CANCEL_REQUEST:
|
||
onNetworkRequestWithdrawn((NetworkRequest) m.obj);
|
||
break;
|
||
default:
|
||
Log.e(mName, "Unhandled message: " + m.what);
|
||
}
|
||
}
|
||
};
|
||
mContext = context;
|
||
mMessenger = new Messenger(handler);
|
||
mName = name;
|
||
}
|
||
|
||
// TODO: consider adding a register() method so ConnectivityManager does not need to call this.
|
||
/** @hide */
|
||
public @Nullable Messenger getMessenger() {
|
||
return mMessenger;
|
||
}
|
||
|
||
/** @hide */
|
||
public @NonNull String getName() {
|
||
return mName;
|
||
}
|
||
|
||
/**
|
||
* Returns the ID of this provider. This is known only once the provider is registered via
|
||
* {@link ConnectivityManager#registerNetworkProvider()}, otherwise the ID is {@link #ID_NONE}.
|
||
* This ID must be used when registering any {@link NetworkAgent}s.
|
||
*/
|
||
public int getProviderId() {
|
||
return mProviderId;
|
||
}
|
||
|
||
/** @hide */
|
||
public void setProviderId(int providerId) {
|
||
mProviderId = providerId;
|
||
}
|
||
|
||
/**
|
||
* Called when a NetworkRequest is received. The request may be a new request or an existing
|
||
* request with a different score.
|
||
*
|
||
* @param request the NetworkRequest being received
|
||
* @param score the score of the network currently satisfying the request, or 0 if none.
|
||
* @param providerId the ID of the provider that created the network currently satisfying this
|
||
* request, or {@link #ID_NONE} if none.
|
||
*
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
public void onNetworkRequested(@NonNull NetworkRequest request,
|
||
@IntRange(from = 0, to = 99) int score, int providerId) {}
|
||
|
||
/**
|
||
* Called when a NetworkRequest is withdrawn.
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
public void onNetworkRequestWithdrawn(@NonNull NetworkRequest request) {}
|
||
|
||
/**
|
||
* Asserts that no provider will ever be able to satisfy the specified request. The provider
|
||
* must only call this method if it knows that it is the only provider on the system capable of
|
||
* satisfying this request, and that the request cannot be satisfied. The application filing the
|
||
* request will receive an {@link NetworkCallback#onUnavailable()} callback.
|
||
*
|
||
* @param request the request that permanently cannot be fulfilled
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
@RequiresPermission(android.Manifest.permission.NETWORK_FACTORY)
|
||
public void declareNetworkRequestUnfulfillable(@NonNull NetworkRequest request) {
|
||
ConnectivityManager.from(mContext).declareNetworkRequestUnfulfillable(request);
|
||
}
|
||
|
||
/**
|
||
* A callback for parties registering a NetworkOffer.
|
||
*
|
||
* This is used with {@link ConnectivityManager#offerNetwork}. When offering a network,
|
||
* the system will use this callback to inform the caller that a network corresponding to
|
||
* this offer is needed or unneeded.
|
||
*
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
public interface NetworkOfferCallback {
|
||
/**
|
||
* Called by the system when a network for this offer is needed to satisfy some
|
||
* networking request.
|
||
*/
|
||
void onNetworkNeeded(@NonNull NetworkRequest request);
|
||
/**
|
||
* Called by the system when this offer is no longer valuable for this request.
|
||
*/
|
||
void onNetworkUnneeded(@NonNull NetworkRequest request);
|
||
}
|
||
|
||
private class NetworkOfferCallbackProxy extends INetworkOfferCallback.Stub {
|
||
@NonNull public final NetworkOfferCallback callback;
|
||
@NonNull private final Executor mExecutor;
|
||
|
||
NetworkOfferCallbackProxy(@NonNull final NetworkOfferCallback callback,
|
||
@NonNull final Executor executor) {
|
||
this.callback = callback;
|
||
this.mExecutor = executor;
|
||
}
|
||
|
||
@Override
|
||
public void onNetworkNeeded(final @NonNull NetworkRequest request) {
|
||
mExecutor.execute(() -> callback.onNetworkNeeded(request));
|
||
}
|
||
|
||
@Override
|
||
public void onNetworkUnneeded(final @NonNull NetworkRequest request) {
|
||
mExecutor.execute(() -> callback.onNetworkUnneeded(request));
|
||
}
|
||
}
|
||
|
||
@GuardedBy("mProxies")
|
||
@NonNull private final ArrayList<NetworkOfferCallbackProxy> mProxies = new ArrayList<>();
|
||
|
||
// Returns the proxy associated with this callback, or null if none.
|
||
@Nullable
|
||
private NetworkOfferCallbackProxy findProxyForCallback(@NonNull final NetworkOfferCallback cb) {
|
||
synchronized (mProxies) {
|
||
for (final NetworkOfferCallbackProxy p : mProxies) {
|
||
if (p.callback == cb) return p;
|
||
}
|
||
}
|
||
return null;
|
||
}
|
||
|
||
/**
|
||
* Register or update an offer for network with the passed capabilities and score.
|
||
*
|
||
* A NetworkProvider's role is to provide networks. This method is how a provider tells the
|
||
* connectivity stack what kind of network it may provide. The score and caps arguments act
|
||
* as filters that the connectivity stack uses to tell when the offer is valuable. When an
|
||
* offer might be preferred over existing networks, the provider will receive a call to
|
||
* the associated callback's {@link NetworkOfferCallback#onNetworkNeeded} method. The provider
|
||
* should then try to bring up this network. When an offer is no longer useful, the stack
|
||
* will inform the provider by calling {@link NetworkOfferCallback#onNetworkUnneeded}. The
|
||
* provider should stop trying to bring up such a network, or disconnect it if it already has
|
||
* one.
|
||
*
|
||
* The stack determines what offers are valuable according to what networks are currently
|
||
* available to the system, and what networking requests are made by applications. If an
|
||
* offer looks like it could connect a better network than any existing network for any
|
||
* particular request, that's when the stack decides the network is needed. If the current
|
||
* networking requests are all satisfied by networks that this offer couldn't possibly be a
|
||
* better match for, that's when the offer is no longer valuable. An offer starts out as
|
||
* unneeded ; the provider should not try to bring up the network until
|
||
* {@link NetworkOfferCallback#onNetworkNeeded} is called.
|
||
*
|
||
* Note that the offers are non-binding to the providers, in particular because providers
|
||
* often don't know if they will be able to bring up such a network at any given time. For
|
||
* example, no wireless network may be in range when the offer would be valuable. This is fine
|
||
* and expected ; the provider should simply continue to try to bring up the network and do so
|
||
* if/when it becomes possible. In the mean time, the stack will continue to satisfy requests
|
||
* with the best network currently available, or if none, keep the apps informed that no
|
||
* network can currently satisfy this request. When/if the provider can bring up the network,
|
||
* the connectivity stack will match it against requests, and inform interested apps of the
|
||
* availability of this network. This may, in turn, render the offer of some other provider
|
||
* low-value if all requests it used to satisfy are now better served by this network.
|
||
*
|
||
* A network can become unneeded for a reason like the above : whether the provider managed
|
||
* to bring up the offered network after it became needed or not, some other provider may
|
||
* bring up a better network than this one, making this network unneeded. A network may also
|
||
* become unneeded if the application making the request withdrew it (for example, after it
|
||
* is done transferring data, or if the user canceled an operation).
|
||
*
|
||
* The capabilities and score act as filters as to what requests the provider will see.
|
||
* They are not promises, but for best performance, the providers should strive to put
|
||
* as much known information as possible in the offer. For the score, it should put as
|
||
* strong a score as the networks will have, since this will filter what requests the
|
||
* provider sees – it's not a promise, it only serves to avoid sending requests that
|
||
* the provider can't ever hope to satisfy better than any current network. For capabilities,
|
||
* it should put all NetworkAgent-managed capabilities a network may have, even if it doesn't
|
||
* have them at first. This applies to INTERNET, for example ; if a provider thinks the
|
||
* network it can bring up for this offer may offer Internet access it should include the
|
||
* INTERNET bit. It's fine if the brought up network ends up not actually having INTERNET.
|
||
*
|
||
* TODO : in the future, to avoid possible infinite loops, there should be constraints on
|
||
* what can be put in capabilities of networks brought up for an offer. If a provider might
|
||
* bring up a network with or without INTERNET, then it should file two offers : this will
|
||
* let it know precisely what networks are needed, so it can avoid bringing up networks that
|
||
* won't actually satisfy requests and remove the risk for bring-up-bring-down loops.
|
||
*
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
@RequiresPermission(android.Manifest.permission.NETWORK_FACTORY)
|
||
public void registerNetworkOffer(@NonNull final NetworkScore score,
|
||
@NonNull final NetworkCapabilities caps, @NonNull final Executor executor,
|
||
@NonNull final NetworkOfferCallback callback) {
|
||
// Can't offer a network with a provider that is not yet registered or already unregistered.
|
||
final int providerId = mProviderId;
|
||
if (providerId == ID_NONE) return;
|
||
NetworkOfferCallbackProxy proxy = null;
|
||
synchronized (mProxies) {
|
||
for (final NetworkOfferCallbackProxy existingProxy : mProxies) {
|
||
if (existingProxy.callback == callback) {
|
||
proxy = existingProxy;
|
||
break;
|
||
}
|
||
}
|
||
if (null == proxy) {
|
||
proxy = new NetworkOfferCallbackProxy(callback, executor);
|
||
mProxies.add(proxy);
|
||
}
|
||
}
|
||
mContext.getSystemService(ConnectivityManager.class)
|
||
.offerNetwork(providerId, score, caps, proxy);
|
||
}
|
||
|
||
/**
|
||
* Withdraw a network offer previously made to the networking stack.
|
||
*
|
||
* If a provider can no longer provide a network they offered, it should call this method.
|
||
* An example of usage could be if the hardware necessary to bring up the network was turned
|
||
* off in UI by the user. Note that because offers are never binding, the provider might
|
||
* alternatively decide not to withdraw this offer and simply refuse to bring up the network
|
||
* even when it's needed. However, withdrawing the request is slightly more resource-efficient
|
||
* because the networking stack won't have to compare this offer to exiting networks to see
|
||
* if it could beat any of them, and may be advantageous to the provider's implementation that
|
||
* can rely on no longer receiving callbacks for a network that they can't bring up anyways.
|
||
*
|
||
* Warning: This method executes asynchronously. The NetworkOfferCallback object can continue
|
||
* receiving onNetworkNeeded and onNetworkUnneeded callbacks even after this method has
|
||
* returned. In this case, it is on the caller to take appropriate steps in order to prevent
|
||
* bringing up a network.
|
||
*
|
||
* @hide
|
||
*/
|
||
@SystemApi
|
||
@RequiresPermission(android.Manifest.permission.NETWORK_FACTORY)
|
||
public void unregisterNetworkOffer(final @NonNull NetworkOfferCallback callback) {
|
||
final NetworkOfferCallbackProxy proxy = findProxyForCallback(callback);
|
||
if (null == proxy) return;
|
||
synchronized (mProxies) {
|
||
mProxies.remove(proxy);
|
||
}
|
||
mContext.getSystemService(ConnectivityManager.class).unofferNetwork(proxy);
|
||
}
|
||
}
|