Android M Multi-Network Solution
1. Android NetworkAndroid network APIControl/Monitor APIData communication APIConnectivityManagerConnectivityService NetworkFactoryNetdLinux Network API
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1. Android Network
| Control/Monitor API | Data communication API |
|---|---|
| ConnectivityManager ConnectivityService NetworkFactory Netd Linux Network API | Java Socket / Android Jni socket/ packaged API based on socket(such as http/ssl and so on.) Linux Socket |
Control/Monitor API: like the control bus of a device. The primary responsibilities of these API:
1) Monitor network connections (Wi-Fi, mobile, Ethernet etc.)
2) Send broadcast intents when network connectivity changes
3) Attempt to "fail over" to another network when connectivity to a network is lost
4) Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks
5) Provide an API that allows applications to request and select networks for their data traffic
6) start/stop the assigned network, etc.
Data communication API: like the data bus of a device. The primary responsibilities of these API:
1) Provide some API for an application to communicate with other peer in this network.
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2. Android Multi-network App.
Before show the APP, we introduce some Multi-network API for you.
1) Binds the current process to network:
boolean bindProcessToNetwork (Network network)To assign a network interface by force, you should use this api.
2) Build network request:
void registerNetworkCallback (NetworkRequest request,
ConnectivityManager.NetworkCallback networkCallback)And a demo for this api's application:
NetworkRequest.Builder builder;
builder = new NetworkRequest.Builder();
// Clear all capability.
builder.removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN);
builder.removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
builder.removeCapability(NetworkCapabilities.NET_CAPABILITY_TRUSTED);
builder.addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR);
CMgr.registerNetworkCallback(builder.build(), new ConnectivityManager.NetworkCallback(){
@Override
public void onAvailable(Network network) {
// When this network is on available
...........
}
@Override
public void onLost(Network network) {
// When this network is on lost
......
}
});About the android Multi-network App demo, please refer to https://github.com/jwzl/MultiNetwork-master/tree/master/Android_Demo/NetClient.
In theory, since android M support Multi-network, this should be all steps for Multi-network.
But in reality, there are stil some bug to be fixed by modifying the source code of framework.
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3. Android M network's mechanism of connectivity & mangement
To study the Android Multi-network's mechanism of connectivity & mangement, there are two important Objects to be clear: Networkrequest and NetworkAgent.
3.1 Networkrequest
As the name described, it's a request for one or more network type. For example, you need
a network of ethernet type, you should build a networkrequest for ethernet. And if you need
a network of all type (ethernet, wifi, mobile), you should build a networkrequest for all network
type.
3.2 NetworkAgent
As the name described, it's a agent of a network. This network is controled or monitored by
this networkAgent, that is , the networkAgent is stand for the network in a sense. The NetworkAgent
is created by Networkfactory. For a network type, it just has only one networkfactroy, and for a networkfactory,
it can have many networkAgent. The networkAgent is just only for one networktype.
For example, the networkfactory is like a water Supplement factory, and the networkAgent is like a water tap in your
house. Once you need the water, you just open the water tap to get water instead of going to the water Supplement factory.
Network interface is started/stopped indirectly by the NetworkAgent (directly by NetworkFactory).
3.3 The core logic of the network's mechanism
Once you know the two objects above, it's easy to read this code segment. it's the core
logic of the network's mechanism. The function named rematchNetworkAndRequests(), and it's
called when Networkrequest/NetworkAgent is registered, or this network state is changed.
The responsibility of rematchNetworkAndRequests() is mach/rematch the networkAgentInfo and networkrequest.
NetworkAgentInfo is the information of the networkAgent.
private void rematchNetworkAndRequests(NetworkAgentInfo newNetwork,
ReapUnvalidatedNetworks reapUnvalidatedNetworks) {
if (!newNetwork.created) return; /* If no created, then return */
boolean keep = newNetwork.isVPN(); /* is VPN ?*/
boolean isNewDefault = false;
NetworkAgentInfo oldDefaultNetwork = null;
if (VDBG) log("rematching " + newNetwork.name());
// Find and migrate to this Network any NetworkRequests for
// which this network is now the best.
ArrayList<NetworkAgentInfo> affectedNetworks = new ArrayList<NetworkAgentInfo>();
ArrayList<NetworkRequestInfo> addedRequests = new ArrayList<NetworkRequestInfo>();
if (VDBG) log(" network has: " + newNetwork.networkCapabilities);
for (NetworkRequestInfo nri : mNetworkRequests.values()) {
//Qing: mNetworkRequests is all current network request info's lists.
// Qing: According to the networkreuest to get the corresponding network agent; if the network agent
// is not added(haven't been enabled), then , return null, and it means that this is a new networrk
// Otherwise, it will retrun the current available
// network.
final NetworkAgentInfo currentNetwork = mNetworkForRequestId.get(nri.request.requestId);
/* Qing: this request wether satisfies this new network ? <=> is the request for this network ? */
// that is , if the networkreuqest is for Ethernet, but the new network is wifi, then
// the "satisfies = false", If the networkreuqest is for Ethernet, and the new newtwork
// is the Ethernet, then "satisfies = true". If the networkreuqest is for general, new network
// can satisfies, that is "satisfies = true"
final boolean satisfies = newNetwork.satisfies(nri.request);
/* Qing:
If the requested network has existed, and the request is matched the new network! then
do nothing and countinue the next request!
the new nettwork need find new network reuest to match!
*/
if (newNetwork == currentNetwork && satisfies) {
if (VDBG) {
log("Network " + newNetwork.name() + " was already satisfying" +
" request " + nri.request.requestId + ". No change.");
}
keep = true;
continue;
}
// check if it satisfies the NetworkCapabilities
if (VDBG) log(" checking if request is satisfied: " + nri.request);
// Qing: If the network reuuest is for the new network ?
if (satisfies) {
//Qing: the networkrequest is not a network request , then , continuous find
// the next network request! this is a callback listener.
if (!nri.isRequest) {
// This is not a request, it's a callback listener.
// Add it to newNetwork regardless of score.
if (newNetwork.addRequest(nri.request)) addedRequests.add(nri);
continue;
}
// next check if it's better than any current network we're using for
// this request
if (VDBG) {
log("currentScore = " +
(currentNetwork != null ? currentNetwork.getCurrentScore() : 0) +
", newScore = " + newNetwork.getCurrentScore());
}
//Qing:
// currentNetwork == null is means that the network request is the new request and
// not matched. the new network will match the networkrequest.
//Qing:
// currentNetwork.getCurrentScore() < newNetwork.getCurrentScore() is means that
// the network request has matched a networkagent different from the new netwwork.( since it
// has > 1 kinds network Compatibility， such as which compitable with Ethernet and mobile )
// but the new network's score is more than the current network. then the new network
// will replace the current network.
// In general, the default network has multiple network compatibility. Others just has one kinds
// network compatibility.
//QIng:
//All in speaking, this is match the networkAgent & Networkrequest.
if (currentNetwork == null ||
currentNetwork.getCurrentScore() < newNetwork.getCurrentScore()) {
if (DBG) log("rematch for " + newNetwork.name());
if (currentNetwork != null) {
if (DBG) log(" accepting network in place of " + currentNetwork.name());
//Qing : the network request will be removed from this network data structure.
currentNetwork.networkRequests.remove(nri.request.requestId);
currentNetwork.networkLingered.add(nri.request);
// Qing: the current network will be affected. maybe the current network
// will be down!
affectedNetworks.add(currentNetwork);
} else {
if (DBG) log(" accepting network in place of null");
}
unlinger(newNetwork);
//Qing: Add the matched pairs to map of [networkrequestid, networkagent ]
// also maybe : replace the current network by the new network in the hash table;
mNetworkForRequestId.put(nri.request.requestId, newNetwork);
//Qing: add this request into the [networkRequests] member of NetworkAngentinfo
if (!newNetwork.addRequest(nri.request)) {
Slog.wtf(TAG, "BUG: " + newNetwork.name() + " already has " + nri.request);
}
//Qing: the new network will match all matched network request. So, it need a
// lists to store , we named it as "addedRequests"
addedRequests.add(nri);
keep = true;
// Tell NetworkFactories about the new score, so they can stop
// trying to connect if they know they cannot match it.
// TODO - this could get expensive if we have alot of requests for this
// network. Think about if there is a way to reduce this. Push
// netid->request mapping to each factory?
// Qing: Send current score to all network factories. every network factory
// will according to the score to process their own netwok.
// Qing:
// As default, every one network factory will compare the score with it's
// own score & network Capabilities. If the score < network factory's score,
// then, network factory will try to start own network.
// If the score > network factory's score, then, network factory will try to shut down own network.
sendUpdatedScoreToFactories(nri.request, newNetwork.getCurrentScore());
//Qing: If the network request is system default network request, system
// will close the old network. Because the default network request is compatible
// any network, so, any a new network will try to match the default network request.
// If it is the first network, the default network request will match this network.
// and the first network will become the system default network.
// The following logical will close the previous the default netwwork.
if (mDefaultRequest.requestId == nri.request.requestId) {
isNewDefault = true;
oldDefaultNetwork = currentNetwork;
}
}
//Qing:
// it should be teardown!
} else if (newNetwork.networkRequests.get(nri.request.requestId) != null) {// Qing: Not satisfies
// If "newNetwork" is listed as satisfying "nri" but no longer satisfies "nri",
// mark it as no longer satisfying "nri". Because networks are processed by
// rematchAllNetworkAndRequests() in descending score order, "currentNetwork" will
// match "newNetwork" before this loop will encounter a "currentNetwork" with higher
// score than "newNetwork" and where "currentNetwork" no longer satisfies "nri".
// This means this code doesn't have to handle the case where "currentNetwork" no
// longer satisfies "nri" when "currentNetwork" does not equal "newNetwork".
//Qing: Current network request is not matched for the new network, but the newwork's
// network request lsits contain this request. then system will remove the request from
// the new work request lists. this logcal can be hard to reach.
if (DBG) {
log("Network " + newNetwork.name() + " stopped satisfying" +
" request " + nri.request.requestId);
}
newNetwork.networkRequests.remove(nri.request.requestId);
if (currentNetwork == newNetwork) {
mNetworkForRequestId.remove(nri.request.requestId);
sendUpdatedScoreToFactories(nri.request, 0);
} else {
if (nri.isRequest == true) {
Slog.wtf(TAG, "BUG: Removing request " + nri.request.requestId + " from " +
newNetwork.name() +
" without updating mNetworkForRequestId or factories!");
}
}
// TODO: technically, sending CALLBACK_LOST here is
// incorrect if nri is a request (not a listen) and there
// is a replacement network currently connected that can
// satisfy it. However, the only capability that can both
// a) be requested and b) change is NET_CAPABILITY_TRUSTED,
// so this code is only incorrect for a network that loses
// the TRUSTED capability, which is a rare case.
callCallbackForRequest(nri, newNetwork, ConnectivityManager.CALLBACK_LOST);
}
}
// Linger any networks that are no longer needed.
// Qing: If these replaced networks is not needed, then system will linger (closed ) the network!
for (NetworkAgentInfo nai : affectedNetworks) {
if (nai.lingering) {
// Already lingered. Nothing to do. This can only happen if "nai" is in
// "affectedNetworks" twice. The reasoning being that to get added to
// "affectedNetworks", "nai" must have been satisfying a NetworkRequest
// (i.e. not lingered) so it could have only been lingered by this loop.
// unneeded(nai) will be false and we'll call unlinger() below which would
// be bad, so handle it here.
} else if (unneeded(nai)) {
//Qing: If the network still has matched network request, then the network
//is still needed!
linger(nai);
} else {
// Clear nai.networkLingered we might have added above.
unlinger(nai);
}
}
//Qing: If the newwork is default network, then switch to the new network!
if (isNewDefault) {
// Notify system services that this network is up.
makeDefault(newNetwork);
synchronized (ConnectivityService.this) {
// have a new default network, release the transition wakelock in
// a second if it's held. The second pause is to allow apps
// to reconnect over the new network
if (mNetTransitionWakeLock.isHeld()) {
mHandler.sendMessageDelayed(mHandler.obtainMessage(
EVENT_CLEAR_NET_TRANSITION_WAKELOCK,
mNetTransitionWakeLockSerialNumber, 0),
1000);
}
}
}
// do this after the default net is switched, but
// before LegacyTypeTracker sends legacy broadcasts
for (NetworkRequestInfo nri : addedRequests) notifyNetworkCallback(newNetwork, nri);
if (isNewDefault) {
// Maintain the illusion: since the legacy API only
// understands one network at a time, we must pretend
// that the current default network disconnected before
// the new one connected.
//Qing: the will maybe close old default network
if (oldDefaultNetwork != null) {
mLegacyTypeTracker.remove(oldDefaultNetwork.networkInfo.getType(),
oldDefaultNetwork, true);
}
mDefaultInetConditionPublished = newNetwork.lastValidated ? 100 : 0;
mLegacyTypeTracker.add(newNetwork.networkInfo.getType(), newNetwork);
notifyLockdownVpn(newNetwork);
}
// Qing: is for vpn
if (keep) {
// Notify battery stats service about this network, both the normal
// interface and any stacked links.
// TODO: Avoid redoing this; this must only be done once when a network comes online.
try {
final IBatteryStats bs = BatteryStatsService.getService();
final int type = newNetwork.networkInfo.getType();
final String baseIface = newNetwork.linkProperties.getInterfaceName();
bs.noteNetworkInterfaceType(baseIface, type);
for (LinkProperties stacked : newNetwork.linkProperties.getStackedLinks()) {
final String stackedIface = stacked.getInterfaceName();
bs.noteNetworkInterfaceType(stackedIface, type);
NetworkStatsFactory.noteStackedIface(stackedIface, baseIface);
}
} catch (RemoteException ignored) {
}
// This has to happen after the notifyNetworkCallbacks as that tickles each
// ConnectivityManager instance so that legacy requests correctly bind dns
// requests to this network. The legacy users are listening for this bcast
// and will generally do a dns request so they can ensureRouteToHost and if
// they do that before the callbacks happen they'll use the default network.
//
// TODO: Is there still a race here? We send the broadcast
// after sending the callback, but if the app can receive the
// broadcast before the callback, it might still break.
//
// This *does* introduce a race where if the user uses the new api
// (notification callbacks) and then uses the old api (getNetworkInfo(type))
// they may get old info. Reverse this after the old startUsing api is removed.
// This is on top of the multiple intent sequencing referenced in the todo above.
for (int i = 0; i < newNetwork.networkRequests.size(); i++) {
NetworkRequest nr = newNetwork.networkRequests.valueAt(i);
if (nr.legacyType != TYPE_NONE && isRequest(nr)) {
// legacy type tracker filters out repeat adds
mLegacyTypeTracker.add(nr.legacyType, newNetwork);
}
}
// A VPN generally won't get added to the legacy tracker in the "for (nri)" loop above,
// because usually there are no NetworkRequests it satisfies (e.g., mDefaultRequest
// wants the NOT_VPN capability, so it will never be satisfied by a VPN). So, add the
// newNetwork to the tracker explicitly (it's a no-op if it has already been added).
if (newNetwork.isVPN()) {
mLegacyTypeTracker.add(TYPE_VPN, newNetwork);
}
}
//Qing: teardown all unneeded network!
if (reapUnvalidatedNetworks == ReapUnvalidatedNetworks.REAP) {
for (NetworkAgentInfo nai : mNetworkAgentInfos.values()) {
if (unneeded(nai)) {
if (DBG) log("Reaping " + nai.name());
teardownUnneededNetwork(nai);
}
}
}
}private void evalRequest(NetworkRequestInfo n) {
if (VDBG) log("evalRequest");
//Qing:
// If the this network(factory)'s score is more than other network, then,
// System will start this network.
if (n.requested == false && n.score < mScore &&
n.request.networkCapabilities.satisfiedByNetworkCapabilities(
mCapabilityFilter) && acceptRequest(n.request, n.score)) {
if (VDBG) log(" needNetworkFor");
needNetworkFor(n.request, n.score);
n.requested = true;
//Qing:
//If this network(factory)'s score is less than other network, then, System will
//Shutdown this network.
// In reality, Ethernet & wifi not stop this network. just mobile try to shutdown
// this network.
} else if (n.requested == true &&
(n.score > mScore || n.request.networkCapabilities.satisfiedByNetworkCapabilities(
mCapabilityFilter) == false || acceptRequest(n.request, n.score) == false)) {
if (VDBG) log(" releaseNetworkFor");
// We must support the mult-network
releaseNetworkFor(n.request);
n.requested = false;
} else {
if (VDBG) log(" done");
}
}For the one networkrequest
For the mult-networkrequest:
For the mult-network, every networkrequest is same as the "One Networkrequest" when matching. we should
modify the framework to finish it.
For the mult-network, every networkrequest is same as the "One Networkrequest" when matching. we should
modify the framework to finish it.
3.4 The process for starting Ethernet
Start/stop the ethernet only with the networkrequest.
a) start/stop the Ethernet by networkrequest
-> [EthernetService.java]: onBootPhase()
Finaly, this will call start() in [EthernetNetworkFactory.java]。
-> [EthernetNetworkFactory.java]:start()
Finaly, this will call register().
-> [ConnectivityService.java]: registerNetworkFactory():
This function will call EVENT_REGISTER_NETWORK_FACTORY， and finally call handleRegisterNetworkFactory();
-> [ConnectivityService.java]: handleRegisterNetworkFactory()
This function will call nfi.asyncChannel.connect（）and send CMD_CHANNEL_HALF_CONNECTED message. and the message is recieved by handleAsyncChannelHalfConnect().
-> [ConnectivityService.java]: class NetworkStateTrackerHandler 中的handleMessage（）
case AsyncChannel.CMD_CHANNEL_HALF_CONNECTED: {
handleAsyncChannelHalfConnect(msg);
break;
}-> [ConnectivityService.java]: handleAsyncChannelHalfConnect()
private void handleAsyncChannelHalfConnect(Message msg) {
if (mNetworkFactoryInfos.containsKey(msg.replyTo)) {
if (msg.arg1 == AsyncChannel.STATUS_SUCCESSFUL) {
..............
for (NetworkRequestInfo nri : mNetworkRequests.values()) {
if (nri.isRequest == false) continue;
NetworkAgentInfo nai = mNetworkForRequestId.get(nri.request.requestId);
ac.sendMessage(android.net.NetworkFactory.CMD_REQUEST_NETWORK,
(nai != null ? nai.getCurrentScore() : 0), 0, nri.request);
..............................
}This function will send [CMD_REQUEST_NETWORK] to all factories, and the [CMD_REQUEST_NETWORK] is
processed by handleAddRequest(). Which is same as the sendUpdatedScoreToFactories().-> [ NetworkFactory.java]: handleAddRequest()
protected void handleAddRequest(NetworkRequest request, int score) {
...........
evalRequest(n);
}-> [ NetworkFactory.java]: evalRequest()
private void evalRequest(NetworkRequestInfo n) {
.....................
// Then the n.score =0, since ethernet has no ip.
if (n.requested == false && n.score < mScore &&
n.request.networkCapabilities.satisfiedByNetworkCapabilities(
mCapabilityFilter) && acceptRequest(n.request, n.score)) {
needNetworkFor(n.request, n.score);
n.requested = true;
} else if (n.requested == true &&
(n.score > mScore || n.request.networkCapabilities.satisfiedByNetworkCapabilities(
mCapabilityFilter) == false || acceptRequest(n.request, n.score) == false)) {
// We must support the mult-network
//releaseNetworkFor(n.request);
//n.requested = false;
} else {
if (VDBG) log(" done");
}
}protected void needNetworkFor(NetworkRequest networkRequest, int score) {
if (++mRefCount == 1) startNetwork();
}protected void startNetwork() {
onRequestNetwork();
}public void onRequestNetwork() {
...............
Thread dhcpThread = new Thread(new Runnable() {
public void run() {
.......................
// Run DHCP to get ip address
DhcpResults dhcpResults = new DhcpResults();
.........................
synchronized(EthernetNetworkFactory.this) {
....................
// Create our NetworkAgent.
mNetworkAgent = new NetworkAgent(mFactory.getLooper(), mContext,
NETWORK_TYPE, mNetworkInfo, mNetworkCapabilities, mLinkProperties,
NETWORK_SCORE) {
........................
};
}
}
});
dhcpThread.start();
}-> [ConnectivityService.java]: handleRegisterNetworkAgent() :
-> [ConnectivityService.java]: updateNetworkInfo():
When finished the updateNetworkInfo(), the Ethernet will work. And everything about
Ethernet is Okay.
b) Ethernet update status
-> [NetlinkHandler.cpp]:onEvent:
Netd will monitor the Ethernet's state, and will send some event to android network
framework. such as NetlinkEvent::Action::kRemove，NetlinkEvent::Action::kLinkUp.
When send the NetlinkEvent::Action::kLinkUp/kLinkDown event, system will finally call updateInterfaceState().
-> [EthernetNetworkFactory.java]: updateInterfaceState():
This will call mFactory.setScoreFilter() to send CMD_SET_SCORE messagee, and finally call handleSetScore（）
to set this network's score.
-> [NetworkFactory.java]: handleSetScore():
This will set this network's score and re-evaluate this network.
3.5 The process for starting Mobile
a) On/Off the mobile by the user interface:
<- [DcTrackerBase.java]: onSetUserDataEnabled(boolean enabled)
onSetUserDataEnabled(boolean enabled){
if (enabled) {
onTrySetupData(Phone.REASON_DATA_ENABLED);
} else {
onCleanUpAllConnections(Phone.REASON_DATA_SPECIFIC_DISABLED);
}
} If disabled,onCleanUpAllConnections() will call tearDown() to shutdown the mobile network.
<-【DcTracker.java】:onTrySetupData()
onTrySetupData() -> TrySetupData() -> setupData();
setupData()-> bringUp().
-> [DcAsyncChannel.java] bringUp():
There are two functions: bringUp（） and tearDown（） in DcAsyncChannel.java, bringUp（） is for starting the mobile network，
and tearDown（） is for shutting down the mobile network.
bringUp() will send EVENT_CONNECT event to ActivatingState；
-> [DataConnection.java]: onConnect()
1) . This will send EVENT_SETUP_DATA_CONNECTION_DONE event to DcActivatingState.
2) When finished, this will call mPhone.mCi.setupDataCall() to start mobile network(such as starting pppd)
[RIL.java]: setupDataCall() -> .... -> pppd_start(). When start the pppd, Ip will be getted.
-> [DataConnection.java]: DcActivatingState : processMessage（）
case EVENT_SETUP_DATA_CONNECTION_DONE:
...............
switch (result) {
case SUCCESS:
// All is well
mDcFailCause = DcFailCause.NONE;
transitionTo(mActiveState);
break;
}private class DcActiveState extends State {
@Override public void enter() {
..............................
if (createNetworkAgent) {
mNetworkAgent = new DcNetworkAgent(getHandler().getLooper(), mPhone.getContext(),
"DcNetworkAgent", mNetworkInfo, makeNetworkCapabilities(), mLinkProperties,
50, misc);
}
}
}When new the father class(NetworkAgent), registerNetworkAgent() will be called .
-> [NetworkAgent.java]: registerNetworkAgent():
-> [ConnectivityService.java]: handleRegisterNetworkAgent() :
-> [ConnectivityService.java]: updateNetworkInfo():
When finished the updateNetworkInfo(), mobile networkAgent will match with
the mobile networkrequest. And the mobile will work.
b) ON/OFF the mobile by networkrequest:
When the rematchNetworkAndRequests() is called or sendUpdatedScoreToFactories() is called,
this will maybe ON/OFF the mobile network.
Since the rematchNetworkAndRequests() will call sendUpdatedScoreToFactories(), let's start
from sendUpdatedScoreToFactories().
-> [ConnectivityService.java]: sendUpdatedScoreToFactories()
private void sendUpdatedScoreToFactories(NetworkRequest networkRequest, int score) {
.......
for (NetworkFactoryInfo nfi : mNetworkFactoryInfos.values()) {
nfi.asyncChannel.sendMessage(android.net.NetworkFactory.CMD_REQUEST_NETWORK, score, 0,
networkRequest);
}
}-> [ NetworkFactory.java]: handleAddRequest()
About this detailed call relationship，please refer to the Ethernet's part.
-> [ NetworkFactory.java]: evalRequest()
-> [ NetworkFactory.java]: needNetworkFor();
DctController.java Overwrite this needNetworkFor().
-> [DctController.java]: needNetworkFor()
protected void needNetworkFor(NetworkRequest networkRequest, int score) {
....................
DcTrackerBase dcTracker =((PhoneBase)mPhone).mDcTracker;
String apn = apnForNetworkRequest(networkRequest);
if (dcTracker.isApnSupported(apn)) {
requestNetwork(networkRequest, dcTracker.getApnPriority(apn), l);
}
......
}requestNetwork()->processRequests()->onProcessRequest();
-> [DctController.java]: onProcessRequest()
private void onProcessRequest() {
.......................
// if we have no active phones or the active phone is the desired, make requests
if (activePhoneId == INVALID_PHONE_INDEX || activePhoneId == requestedPhoneId) {
Iterator<Integer> iterator = mRequestInfos.keySet().iterator();
while (iterator.hasNext()) {
RequestInfo requestInfo = mRequestInfos.get(iterator.next());
if (requestInfo.executedPhoneId != INVALID_PHONE_INDEX) continue;
if (getRequestPhoneId(requestInfo.request) == requestedPhoneId) {
mDcSwitchAsyncChannel[requestedPhoneId].connect(requestInfo);
}
}
} else {
// otherwise detatch so we can try connecting to the high-priority phone
mDcSwitchAsyncChannel[activePhoneId].disconnectAll();
}
}This function will send REQ_CONNECT message to class AttachingState in the DcSwitchStateMachine.java.
And the message is processed by processMessage().
-> [DcSwitchStateMachine.java]: class AttachingState::processMessage()
DctController.getInstance().executeRequest(apnRequest);
-> [DctController.java]: executeRequest
void executeRequest(RequestInfo request) {
sendMessage(obtainMessage(EVENT_EXECUTE_REQUEST, request));
}-> [DctController.java]: onExecuteRequest()
private void onExecuteRequest(RequestInfo requestInfo) {
if (requestInfo.executedPhoneId == INVALID_PHONE_INDEX &&
mRequestInfos.containsKey(requestInfo.request.requestId)) {
......................
dcTracker.incApnRefCount(apn, requestInfo.getLog());
}
}public void incRefCount(LocalLog log) {
synchronized (mRefCountLock) {
if (mRefCount == 0) {
// we wanted to leave the last in so it could actually capture the tear down
// of the network
requestLog("clearing log with size=" + mLocalLogs.size());
mLocalLogs.clear();
}
if (mLocalLogs.contains(log)) {
log.log("ApnContext.incRefCount has duplicate add - " + mRefCount);
} else {
mLocalLogs.add(log);
log.log("ApnContext.incRefCount - " + mRefCount);
}
if (mRefCount++ == 0) {
mDcTracker.setEnabled(mDcTracker.apnTypeToId(mApnType), true);
}
}
}This function will send EVENT_ENABLE_NEW_APN message to call onEnableApn().
-> 【DcTracker.java】:onEnableApn()
-> 【DcTracker.java】:applyNewState()
-> [DcTracker.java】: trySetupData()
trySetupData() -> bringUp()-> ...... -> [ConnectivityService.java]: updateNetworkInfo().
Then, the following steps are same as "On/Off the mobile by the user interface".
"That is, Mobile network is ON/OFF either by networkrequest or by user api."
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4. The network status Icon's issue for Android M Multi-network.
4.1 Display the network status Icon by default.
Let's use mobile network as example:
-> [MobileSignalController.java]: onSignalStrengthsChanged()
class MobilePhoneStateListener extends PhoneStateListener {
.....
@Override
public void onSignalStrengthsChanged(SignalStrength signalStrength) {
mSignalStrength = signalStrength;
updateTelephony();
}
....
}private final void updateTelephony() {
....
notifyListenersIfNecessary();
}public void notifyListenersIfNecessary() {
if (isDirty()) {
saveLastState();
notifyListeners();
}
}This function will set the status Icon of mobile network.
As default, this is Okay, but in mult-network, some status Icon's
will be wrong. such as wifi's or mobile 's status Icon will be always with a "!",
and so on. That's why ?
4.2 Display the network status Icon under the mult-network.
In reality, before we call notifyListenersIfNecessary(), we should tell the SignalControler
about this status of this network. SignalControler only know the default network's status by default.
"So, we should use the following function instead of notifyListenersIfNecessary() in
[MobileSignalController.java]:updateTelephony()", Let's show your details:
-> [NetworkControllerImpl.java] : updateConnectivity()
private void updateConnectivity() {
//Qing:
// Clear the mConnectedTransports & mValidatedTransports sets.
// The mConnectedTransports recorded all connected network type.
// The mValidatedTransports recorded all Validated network type.
// (What is Validated? it's on work. can ping www.baidu.com )
mConnectedTransports.clear();
mValidatedTransports.clear();
//Qing:
// Get the all NetworkCapabilities from the default network.
// Although the default network support all networktype, but at one time,
// it just has one network type is Validated.
// Qing:
// To support the mult-network, you should modify the function getDefaultNetworkCapabilitiesForUser()
// in ConnectivityService.java. you should add the Capabilities (include default network, mobile, wifi)
// in this function. Then, ValidatedTransports sets will include other Validated networks but not just
// the default network.
for (NetworkCapabilities nc :
mConnectivityManager.getDefaultNetworkCapabilitiesForUser(mCurrentUserId)) {
//Qing:
// This network
for (int transportType : nc.getTransportTypes()) {
mConnectedTransports.set(transportType);
//Qing:
// If the network is Validated ?
if (nc.hasCapability(NET_CAPABILITY_VALIDATED)) {
mValidatedTransports.set(transportType);
}
}
}
mInetCondition = !mValidatedTransports.isEmpty();
pushConnectivityToSignals();
}private void pushConnectivityToSignals() {
// We want to update all the icons, all at once, for any condition change
for (MobileSignalController mobileSignalController : mMobileSignalControllers.values()) {
mobileSignalController.updateConnectivity(mConnectedTransports, mValidatedTransports);
}
mWifiSignalController.updateConnectivity(mConnectedTransports, mValidatedTransports);
mEthernetSignalController.updateConnectivity(mConnectedTransports, mValidatedTransports);
}-> [MobileSignalController.java]: updateConnectivity()
public void updateConnectivity(BitSet connectedTransports, BitSet validatedTransports) {
boolean isValidated = validatedTransports.get(mTransportType);
mCurrentState.isDefault = connectedTransports.get(mTransportType);
// Only show this as not having connectivity if we are default.
mCurrentState.inetCondition = (isValidated || !mCurrentState.isDefault) ? 1 : 0;
notifyListenersIfNecessary();
}call notifyListenersIfNecessary() will update the mobile status Icon.
Otherwise，"isValidated" is always false, After call notifyListenersIfNecessary(), the status will
still be unValidated. If the status is unValidated, the status icon will be displayed with the "!".
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
5. The issue of route & DNS on Android M.
If no network is LAN in mult-network, you can directly skip this chapter.
In the android M mult-network, there are individual route to every network interface.
But for the DNS, it has some unexpection.
If there is a LAN in your android mult-network system, You may face some troubles.
"Other networks can't access any websit by DNS, but it's okay by the IP address".
It's quite terrible，and that's why ?
Let's show you the reason:
Generally， system get DNS by GetHostByName() or GetHostByAddr(). Finally, these api will
call the corresponding function in DnsProxyListener.cpp.
-> [DnsProxyListener.cpp]: GetHostByNameCmd::runCommand()
int DnsProxyListener::GetHostByNameCmd::runCommand(SocketClient *cli,
int argc, char **argv) {
..................
uint32_t mark = mDnsProxyListener->mNetCtrl->getNetworkForDns(&netId, uid);
....
DnsProxyListener::GetHostByNameHandler* handler =
new DnsProxyListener::GetHostByNameHandler(cli, name, af, netId, mark);
handler->start();
return 0;
}2. according to the netid to get the dns.
-> [NetworkController.cpp]: getNetworkForDns()
uint32_t NetworkController::getNetworkForDns(unsigned* netId, uid_t uid) const {
.....
if (checkUserNetworkAccessLocked(uid, *netId) == 0) {
fwmark.explicitlySelected = true;
} else {
......
if (virtualNetwork && virtualNetwork->getHasDns()) {
*netId = virtualNetwork->getNetId();
} else {
*netId = mDefaultNetId; //Qing: we should modify this to setting the correct netid####
}
}
......
}No matter who want to get the dns, this function will always return the default network's id.
If the default network is ethernet && ethernet is LAN (No DNS server), this function will always return a
network's id of ethernet. But the DNS of ethernet is invalid. So, system always get a invalid DNS.
And it will can't access any websit by DNS.
-> [DnsProxyListener.cpp]: GetHostByNameHandler::run()
handler->start() will call GetHostByNameHandler::run() function.
void DnsProxyListener::GetHostByNameHandler::run() {
struct hostent* hp;
//Qing: Get the DNS according to netid
hp = android_gethostbynamefornet(mName, mAf, mNetId, mMark);
..........
}
-> who set mDefaultNetId in NetworkController.cpp ?
-> [ConnectivityService.java]:rematchNetworkAndRequests()
private void rematchNetworkAndRequests(NetworkAgentInfo newNetwork,
ReapUnvalidatedNetworks reapUnvalidatedNetworks) {
....
makeDefault(newNetwork);
....
}private void makeDefault(NetworkAgentInfo newNetwork) {
......
mNetd.setDefaultNetId(newNetwork.network.netId);
.....
}public void setDefaultNetId(int netId) {
.....
mConnector.execute("network", "default", "set", netId);
.....
}int CommandListener::NetworkCommand::runCommand(SocketClient* client, int argc, char** argv) {
....
// 0 1 2 3
// network default set <netId>
// network default clear
if (!strcmp(argv[1], "default")) {
......
if (int ret = sNetCtrl->setDefaultNetwork(netId)) {
return operationError(client, "setDefaultNetwork() failed", ret);
}
....
}
}int NetworkController::setDefaultNetwork(unsigned netId){
.......
mDefaultNetId = netId;
} Then, system will set default network id (Ethernet id) for searching
the DNS. But Ethernet has no valid DNS cache. So others will can't access
any website by DNS.
Although Android libc support that every network has own DNS cache, system
always return the DNS of the default network. If the default network is Ethernet
and Ethernet is LAN(No DNS), system will can't access any website by DNS.
So, you should select a network that always has the valid DNS cache, such as mobile,
Wifi and so on. you shold make this network as the default netid for searching
the DNS.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
6. Android network validation on Android M.
What's the validated network? As we described in chapter 4 . Once the network's Capability is NET_CAPABILITY_VALIDATED, this network is validated . That's why ?
After called the updateNetworkInfo(), the network will work. So, there are a lot of work to be done in this
function. Network validation also will be done in this function.
-> [ConnectivityService.java]: updateNetworkInfo()
private void updateNetworkInfo(NetworkAgentInfo networkAgent, NetworkInfo newInfo) {
.....
// Qing:
// This will caused the network validation
// isCaptivePortal() is called.
networkAgent.networkMonitor.sendMessage(NetworkMonitor.CMD_NETWORK_CONNECTED);
scheduleUnvalidatedPrompt(networkAgent);
.....
}
private class DefaultState extends State {
@Override
public boolean processMessage(Message message) {
switch (message.what) {
....
case CMD_NETWORK_CONNECTED:
transitionTo(mEvaluatingState);
return HANDLED;
....
}
}
}
private class EvaluatingState extends State {
.....
@Override
public void enter() {
sendMessage(CMD_REEVALUATE, ++mReevaluateToken, 0);
.......
}
}
public boolean processMessage(Message message) {
switch (message.what) {
case CMD_REEVALUATE:
.............
//Qing:
// isCaptivePortal() will do a URL fetch on "http://connectivitycheck.gstatic.com/generate_204"
// to see if we get the data we expect.
// If this function return 204, this network is okay, then turn to mValidatedState.
//
int httpResponseCode = isCaptivePortal();
if (httpResponseCode == 204) {
transitionTo(mValidatedState);
} else if (httpResponseCode >= 200 && httpResponseCode <= 399) {
transitionTo(mCaptivePortalState);
} else {
// Qing:
// this access is failed, this function will retry to send CMD_REEVALUATE message
// to re-validate this network.
final Message msg = obtainMessage(CMD_REEVALUATE, ++mReevaluateToken, 0);
sendMessageDelayed(msg, mReevaluateDelayMs);
//Qing:
// Send EVENT_NETWORK_TESTED to connectivityService about the INVALID test.
mConnectivityServiceHandler.sendMessage(obtainMessage(
EVENT_NETWORK_TESTED, NETWORK_TEST_RESULT_INVALID, 0,
mNetworkAgentInfo));
.........
}
return HANDLED;
.........
}
}a validated network.
-> [NetworkMonitor.java]: class ValidatedState : enter()
private class ValidatedState extends State {
@Override
public void enter() {
mConnectivityServiceHandler.sendMessage(obtainMessage(EVENT_NETWORK_TESTED,
NETWORK_TEST_RESULT_VALID, 0, mNetworkAgentInfo));
}
}by NETWORK_TEST_RESULT_VALID.
Note:
Once the statemachine enter ValidatedState, statemachine will not re-validate this network and directly tell them that this network is validated when system send CMD_NETWORK_CONNECTED message
-> [ConnectivityService.java]: NetworkStateTrackerHandler： handleMessage()
private class NetworkStateTrackerHandler extends Handler {
.......
public void handleMessage(Message msg) {
case NetworkMonitor.EVENT_NETWORK_TESTED: {
NetworkAgentInfo nai = (NetworkAgentInfo)msg.obj;
if (isLiveNetworkAgent(nai, "EVENT_NETWORK_TESTED")) {
final boolean valid =
(msg.arg1 == NetworkMonitor.NETWORK_TEST_RESULT_VALID);
if (DBG) log(nai.name() + " validation " + (valid ? " passed" : "failed"));
if (valid != nai.lastValidated) {
final int oldScore = nai.getCurrentScore();
nai.lastValidated = valid;
nai.everValidated |= valid;
updateCapabilities(nai, nai.networkCapabilities);
// If score has changed, rebroadcast to NetworkFactories. b/17726566
if (oldScore != nai.getCurrentScore()) sendUpdatedScoreToFactories(nai);
}
updateInetCondition(nai);
......
}
break;
}
}
}private void updateCapabilities(NetworkAgentInfo nai, NetworkCapabilities networkCapabilities) {
.......
//Qing:
// If the last validation is validated, then system will add NET_CAPABILITY_VALIDATED into networkCapabilities
// of this network.
// If the last validation is unvalidated, then system will remove NET_CAPABILITY_VALIDATED into networkCapabilities
// of this network.
if (nai.lastValidated) {
networkCapabilities.addCapability(NET_CAPABILITY_VALIDATED);
} else {
networkCapabilities.removeCapability(NET_CAPABILITY_VALIDATED);
}
.......
}When networkCapabilities has no NET_CAPABILITY_VALIDATED, the network is unvalidated, and the network can't work.
System & app always use the NET_CAPABILITY_VALIDATED to check whether the network is avaliable.
That's all.
-Qing
2017/09/14
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