Android 7.0 APN 拨号上网流程分析
1、前言
在前段时间的项目中遇到客户的设备出现APN断开的情况没有自动连接，后来折腾了一段时间解决了这个问题。现在用这篇博客记录一下APN的选择和连接流程。
2、名词解析
APN：APN指一种网络接入技术，是通过手机上网时必须配置的一个参数，它决定了手机通过哪种接入方式来访问网络。
对于手机用户来说，可以访问的外部网络类型有很多，例如：Internet、WAP网站、集团企业内部网络、行业内部专用网络。而不同的接入点所能访问的范围以及接入的方式是不同的，网络侧如何知道手机激活以后要访问哪个网络从而分配哪个网段的IP呢，这就要靠APN来区分了，即APN决定了用户的手机通过哪种接入方式来访问什么样的网络。
PDN:Packet data network，分组数据网，即常说的Internet，在GPRS网络中代表外部数据网络的总称
3、Android 中APN的存储形式
Android 系统中APN是以apns-conf.xml文件的形式配置的，位于设备中的system/etc目录下。
apn 的配置信息如下：
<apn carrier="ENTEL4G" //运营商
mcc="736" //Mobile Country Code，移动国家码
mnc="02" //Mobile Network Code，移动网络码
apn="4g.entel" //apn名称
user=""
password=""
proxy="" //代理在这里插入代码片
port="" //端口
authtype="2"
type="default,supl" //apn类型
/>
4、初识TelephonyProvider
4.1 apn文件是怎么被解析的呢，设置中的apn信息怎么保存的呢，这里就轮到TelephonyProvider 出场了
TelephonyProvider继承自ContentProvider，在android中的代码路径为：
packages/providers/TelephonyProvider。
它的UML类图如下：
在AndroidManifest.xml中可以看到application 标签中定义了android:process=“com.android.phone” ，这样TelephonyProvider就运行在com.android.phone进程中，也就是packages\services\Telephony 目录下的Telephony服务。
4.2 TelephonyProvider 的onCreate()函数
代码如下：
@Override
public boolean onCreate() {
mOpenHelper = new DatabaseHelper(getContext());
// Call getReadableDatabase() to make sure onUpgrade is called
if (VDBG) log("onCreate: calling getReadableDatabase to trigger onUpgrade");
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
// Update APN db on build update
String newBuildId = SystemProperties.get("ro.build.id", null);
if (!TextUtils.isEmpty(newBuildId)) {
// Check if build id has changed
SharedPreferences sp = getContext().getSharedPreferences(BUILD_ID_FILE,
Context.MODE_PRIVATE);
String oldBuildId = sp.getString(RO_BUILD_ID, "");
if (!newBuildId.equals(oldBuildId)) {
if (DBG) log("onCreate: build id changed from " + oldBuildId + " to " +
newBuildId);
// Get rid of old preferred apn shared preferences
SubscriptionManager sm = SubscriptionManager.from(getContext());
if (sm != null) {
List<SubscriptionInfo> subInfoList = sm.getAllSubscriptionInfoList();
for (SubscriptionInfo subInfo : subInfoList) {
SharedPreferences spPrefFile = getContext().getSharedPreferences(
PREF_FILE_APN + subInfo.getSubscriptionId(), Context.MODE_PRIVATE);
if (spPrefFile != null) {
SharedPreferences.Editor editor = spPrefFile.edit();
editor.clear();
editor.apply();
}
}
}
// Update APN DB
updateApnDb();
} else {
if (VDBG) log("onCreate: build id did not change: " + oldBuildId);
}
sp.edit().putString(RO_BUILD_ID, newBuildId).apply();
} else {
if (VDBG) log("onCreate: newBuildId is empty");
}
if (VDBG) log("onCreate:- ret true");
return true;
}
从上面的代码，我们知道TelephonyProvider初始化时的主要工作包括：
- new DatabaseHelper 创建出数据库；
- 根据build_id的值，如果跟之前的不同则重新load apn xml文件写入到数据库中，并将之前选中的sharepreference记录选中的 apn清除，并且最后将数据中不在apn xml文件中的数据行全部删除。
4.3 TelephonyProvider 的内部类 DatabaseHelper
DatabaseHelper是 TelephonyProvider 的一个内部类，在TelephonyProvider 的onCreate函数中首先被创建。
4.3.1 DatabaseHelper的构造函数中会传入数据的名字用于创建数据库，这个DATABASE_NAME 就是"telephony.db"，创建路径位于：/data/user_de/0/com.android.providers.telephony/
databases/telephony.db
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, getVersion(context));
mContext = context;
}
4.3.2 DatabaseHelper 的onCreate函数
@Override
public void onCreate(SQLiteDatabase db) {
if (DBG) log(“dbh.onCreate:+ db=” + db);
createSimInfoTable(db);
createCarriersTable(db, CARRIERS_TABLE);
initDatabase(db);
if (DBG) log(“dbh.onCreate:- db=” + db);
}
这里可以看到它作了三件事：
1、创建SIM卡信息的表
2、创建运营商信息的表
3、初始化数据库，这里是重点。
4.3.2 DatabaseHelper 的 initDatabase（）初始化作了哪些事
从这个代码中可以看到函数中主要是：
1、使用XML 解析apn-conf.xml文件并写入到数据库中。
2、将数据库中不是xml中的数据清除掉
private void initDatabase(SQLiteDatabase db) {
if (VDBG) log("dbh.initDatabase:+ db=" + db);
// Read internal APNS data
Resources r = mContext.getResources();
XmlResourceParser parser = r.getXml(com.android.internal.R.xml.apns);
int publicversion = -1;
try {
XmlUtils.beginDocument(parser, "apns");
publicversion = Integer.parseInt(parser.getAttributeValue(null, "version"));
loadApns(db, parser);
} catch (Exception e) {
loge("Got exception while loading APN database." + e);
} finally {
parser.close();
}
// Read external APNS data (partner-provided)
XmlPullParser confparser = null;
File confFile = getApnConfFile();
FileReader confreader = null;
if (DBG) log("confFile = " + confFile);
try {
confreader = new FileReader(confFile);
confparser = Xml.newPullParser();
confparser.setInput(confreader);
XmlUtils.beginDocument(confparser, "apns");
// Sanity check. Force internal version and confidential versions to agree
int confversion = Integer.parseInt(confparser.getAttributeValue(null, "version"));
if (publicversion != confversion) {
log("initDatabase: throwing exception due to version mismatch");
throw new IllegalStateException("Internal APNS file version doesn't match "
+ confFile.getAbsolutePath());
}
loadApns(db, confparser);
} catch (FileNotFoundException e) {
// It's ok if the file isn't found. It means there isn't a confidential file
// Log.e(TAG, "File not found: '" + confFile.getAbsolutePath() + "'");
} catch (Exception e) {
loge("initDatabase: Exception while parsing '" + confFile.getAbsolutePath() + "'" +
e);
} finally {
// Get rid of user/carrier deleted entries that are not present in apn xml file.
// Those entries have edited value USER_DELETED/CARRIER_DELETED.
if (VDBG) {
log("initDatabase: deleting USER_DELETED and replacing "
+ "DELETED_BUT_PRESENT_IN_XML with DELETED");
}
// Delete USER_DELETED
db.delete(CARRIERS_TABLE, IS_USER_DELETED + " or " + IS_CARRIER_DELETED, null);
// Change USER_DELETED_BUT_PRESENT_IN_XML to USER_DELETED
ContentValues cv = new ContentValues();
cv.put(EDITED, USER_DELETED);
db.update(CARRIERS_TABLE, cv, IS_USER_DELETED_BUT_PRESENT_IN_XML, null);
// Change CARRIER_DELETED_BUT_PRESENT_IN_XML to CARRIER_DELETED
cv = new ContentValues();
cv.put(EDITED, CARRIER_DELETED);
db.update(CARRIERS_TABLE, cv, IS_CARRIER_DELETED_BUT_PRESENT_IN_XML, null);
if (confreader != null) {
try {
confreader.close();
} catch (IOException e) {
// do nothing
}
}
// Update the stored checksum
setApnConfChecksum(getChecksum(confFile));
}
if (VDBG) log("dbh.initDatabase:- db=" + db);
}
apn的xml 有那些呢 ？根据getApnConfFile 函数可以知道有如下这些目录。
private File getApnConfFile() {
// Environment.getRootDirectory() is a fancy way of saying ANDROID_ROOT or “/system”.
File confFile = new File(Environment.getRootDirectory(), PARTNER_APNS_PATH);
File oemConfFile = new File(Environment.getOemDirectory(), OEM_APNS_PATH);
File updatedConfFile = new File(Environment.getDataDirectory(), OTA_UPDATED_APNS_PATH);
confFile = getNewerFile(confFile, oemConfFile);
confFile = getNewerFile(confFile, updatedConfFile);
return confFile;
}
private static final String PARTNER_APNS_PATH = “etc/apns-conf.xml”;
private static final String OEM_APNS_PATH = “telephony/apns-conf.xml”;
private static final String OTA_UPDATED_APNS_PATH = “misc/apns-conf.xml”;
private static final String OLD_APNS_PATH = “etc/old-apns-conf.xml”;
到这里TelephonyProvider的业务就很清晰了，他就要就是开机的时候会根据build id来判断是否试正常开机还是升级之后的不同版本，如果不同，则重新创建telephony.db数据库，并重新解析加载apn.xml文件写入到数库中。
5、开机之后APN界面是怎么自动选择APN连接的呢 ？
刚开始我以为设置界面开机之后会默认选择一个已连接的APN的逻辑是在设置里面做的，看了一下设置ApnSettings.java相关的代码发现并没有如何选择apn去拨号的操作，
代码路径：packages\apps\Settings\src\com\android\settings\ApnSettings.java
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
final Activity activity = getActivity();
final int subId = activity.getIntent().getIntExtra(SUB_ID,
SubscriptionManager.INVALID_SUBSCRIPTION_ID);
mMobileStateFilter = new IntentFilter(
TelephonyIntents.ACTION_ANY_DATA_CONNECTION_STATE_CHANGED);
setIfOnlyAvailableForAdmins(true);
mSubscriptionInfo = SubscriptionManager.from(activity).getActiveSubscriptionInfo(subId);
mUiccController = UiccController.getInstance();
CarrierConfigManager configManager = (CarrierConfigManager)
getSystemService(Context.CARRIER_CONFIG_SERVICE);
PersistableBundle b = configManager.getConfig();
mHideImsApn = b.getBoolean(CarrierConfigManager.KEY_HIDE_IMS_APN_BOOL);
mAllowAddingApns = b.getBoolean(CarrierConfigManager.KEY_ALLOW_ADDING_APNS_BOOL);
mUserManager = UserManager.get(activity);
}
如果不是上层应用自动拨号的，那就是底层自动选择的了 ？带着疑问我看了一下开机后的log打印流程发现了端倪：在DCTracker的log中发现DcTracker对象被创建后会注册监听RILD上报事件，当上报EVENT_DATA_CONNECTION_ATTACHED 就会创建apn列表并且获取preference apn 进行拨号，当然第一次没有设置是没有preference apn 的，这里就从 apn 列表中选择apn 进行拨号，按着这条线索继续看一下DCTracker 的代码逻辑吧。
6、DCTracker 登场
这里先放一张DCTracker 的相关类图，它是Telephony架构中监听SIM状态的状态变化和拨号的结果，类似于WifiTrakcker或者NetworkMonitor这样的角色。它是跟随着com.android.phone进程启动的时候创建的，不同类型phone 对应着一种DcTracker。
6.1 DcTracker的构造函数
代码路径：frameworks/opt/telephony/src/java/com/android/internal/telephony/dataconnection/DcTracker.java
构造函数很长，但是总结一下就主要干了这几件事：
1、初始化mUiccController 并注册监听SIM状态
2、registerForAllEvents() 注册监听事件。
3、监听数据库变化以及其他的一些初始化工作。
这里看看registerForAllEvents 监听事件。
//***** Constructor
public DcTracker(Phone phone) {
super();
mPhone = phone;
if (DBG) log("DCT.constructor");
mResolver = mPhone.getContext().getContentResolver();
mUiccController = UiccController.getInstance();
mUiccController.registerForIccChanged(this, DctConstants.EVENT_ICC_CHANGED, null);
mAlarmManager =
(AlarmManager) mPhone.getContext().getSystemService(Context.ALARM_SERVICE);
mCm = (ConnectivityManager) mPhone.getContext().getSystemService(
Context.CONNECTIVITY_SERVICE);
IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
filter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
filter.addAction(INTENT_DATA_STALL_ALARM);
filter.addAction(INTENT_PROVISIONING_APN_ALARM);
// TODO - redundent with update call below?
mDataEnabledSettings.setUserDataEnabled(getDataEnabled());
mPhone.getContext().registerReceiver(mIntentReceiver, filter, null, mPhone);
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(mPhone.getContext());
mAutoAttachOnCreation.set(sp.getBoolean(Phone.DATA_DISABLED_ON_BOOT_KEY, false));
mSubscriptionManager = SubscriptionManager.from(mPhone.getContext());
mSubscriptionManager.addOnSubscriptionsChangedListener(mOnSubscriptionsChangedListener);
HandlerThread dcHandlerThread = new HandlerThread("DcHandlerThread");
dcHandlerThread.start();
Handler dcHandler = new Handler(dcHandlerThread.getLooper());
mDcc = DcController.makeDcc(mPhone, this, dcHandler);
mDcTesterFailBringUpAll = new DcTesterFailBringUpAll(mPhone, dcHandler);
mDataConnectionTracker = this;
registerForAllEvents();
update();
mApnObserver = new ApnChangeObserver();
phone.getContext().getContentResolver().registerContentObserver(
Telephony.Carriers.CONTENT_URI, true, mApnObserver);
initApnContexts();
for (ApnContext apnContext : mApnContexts.values()) {
// Register the reconnect and restart actions.
filter = new IntentFilter();
filter.addAction(INTENT_RECONNECT_ALARM + '.' + apnContext.getApnType());
mPhone.getContext().registerReceiver(mIntentReceiver, filter, null, mPhone);
}
// Add Emergency APN to APN setting list by default to support EPDN in sim absent cases
initEmergencyApnSetting();
addEmergencyApnSetting();
mProvisionActionName = "com.android.internal.telephony.PROVISION" + phone.getPhoneId();
mSettingsObserver = new SettingsObserver(mPhone.getContext(), this);
registerSettingsObserver();
}
6.2 registerForAllEvents监听事件
这里最重要的还是EVENT_DATA_CONNECTION_ATTACHED 表示modem 注网完成接下来进行拨号的状态。
private void registerForAllEvents() {
mPhone.mCi.registerForAvailable(this, DctConstants.EVENT_RADIO_AVAILABLE, null);
mPhone.mCi.registerForOffOrNotAvailable(this,
DctConstants.EVENT_RADIO_OFF_OR_NOT_AVAILABLE, null);
mPhone.mCi.registerForDataNetworkStateChanged(this,
DctConstants.EVENT_DATA_STATE_CHANGED, null);
// Note, this is fragile - the Phone is now presenting a merged picture
// of PS (volte) & CS and by diving into its internals you’re just seeing
// the CS data. This works well for the purposes this is currently used for
// but that may not always be the case. Should probably be redesigned to
// accurately reflect what we’re really interested in (registerForCSVoiceCallEnded).
mPhone.getCallTracker().registerForVoiceCallEnded(this,
DctConstants.EVENT_VOICE_CALL_ENDED, null);
mPhone.getCallTracker().registerForVoiceCallStarted(this,
DctConstants.EVENT_VOICE_CALL_STARTED, null);
registerServiceStateTrackerEvents();
// SubscriptionManager.registerForDdsSwitch(this,
// DctConstants.EVENT_CLEAN_UP_ALL_CONNECTIONS, null);
mPhone.mCi.registerForPcoData(this, DctConstants.EVENT_PCO_DATA_RECEIVED, null);
}
public void registerServiceStateTrackerEvents() {
mPhone.getServiceStateTracker().registerForDataConnectionAttached(this,
DctConstants.EVENT_DATA_CONNECTION_ATTACHED, null);
mPhone.getServiceStateTracker().registerForDataConnectionDetached(this,
DctConstants.EVENT_DATA_CONNECTION_DETACHED, null);
mPhone.getServiceStateTracker().registerForDataRoamingOn(this,
DctConstants.EVENT_ROAMING_ON, null);
mPhone.getServiceStateTracker().registerForDataRoamingOff(this,
DctConstants.EVENT_ROAMING_OFF, null);
mPhone.getServiceStateTracker().registerForPsRestrictedEnabled(this,
DctConstants.EVENT_PS_RESTRICT_ENABLED, null);
mPhone.getServiceStateTracker().registerForPsRestrictedDisabled(this,
DctConstants.EVENT_PS_RESTRICT_DISABLED, null);
mPhone.getServiceStateTracker().registerForDataRegStateOrRatChanged(this,
DctConstants.EVENT_DATA_RAT_CHANGED, null);
}
6.3 拨号前的准备工作setupDataOnConnectableApns
RILD注网成功之后会上报Attached 事件，也就是DcTracker监听到EVENT_DATA_CONNECTION_ATTACHED 事件之后会 执行onDataConnectionAttached
case DctConstants.EVENT_DATA_CONNECTION_ATTACHED:
onDataConnectionAttached();
break;
onDataConnectionAttached()函数做一些notify phone 的操作后会执行setupDataOnConnectableApns，这里就开始准备拨号工作了。
这里APN的类型可能有多种，进行遍历之后清除APN的连接状态。最后根据APN的状态判断如果当前APN的类型是isConnectable就开始调用trySetupData(apnContext, waitingApns)正式进入拨号流程了，因为调用setupDataOnConnectableApns时传入的参数是RetryFailures.ALWAYS，所以这里waitingApns 是null。
private void setupDataOnConnectableApns(String reason, RetryFailures retryFailures) {
if (VDBG) log("setupDataOnConnectableApns: " + reason);
if (DBG && !VDBG) {
StringBuilder sb = new StringBuilder(120);
for (ApnContext apnContext : mPrioritySortedApnContexts) {
sb.append(apnContext.getApnType());
sb.append(":[state=");
sb.append(apnContext.getState());
sb.append(",enabled=");
sb.append(apnContext.isEnabled());
sb.append("] ");
}
log("setupDataOnConnectableApns: " + reason + " " + sb);
}
for (ApnContext apnContext : mPrioritySortedApnContexts) {
ArrayList<ApnSetting> waitingApns = null;
if (VDBG) log("setupDataOnConnectableApns: apnContext " + apnContext);
if (apnContext.getState() == DctConstants.State.FAILED
|| apnContext.getState() == DctConstants.State.SCANNING) {
if (retryFailures == RetryFailures.ALWAYS) {
apnContext.releaseDataConnection(reason);
} else if (apnContext.isConcurrentVoiceAndDataAllowed() == false &&
mPhone.getServiceStateTracker().isConcurrentVoiceAndDataAllowed()) {
// RetryFailures.ONLY_ON_CHANGE - check if voice concurrency has changed
apnContext.releaseDataConnection(reason);
} else {
// RetryFailures.ONLY_ON_CHANGE - check if the apns have changed
int radioTech = mPhone.getServiceState().getRilDataRadioTechnology();
ArrayList<ApnSetting> originalApns = apnContext.getWaitingApns();
if (originalApns != null && originalApns.isEmpty() == false) {
waitingApns = buildWaitingApns(apnContext.getApnType(), radioTech);
if (originalApns.size() != waitingApns.size() ||
originalApns.containsAll(waitingApns) == false) {
apnContext.releaseDataConnection(reason);
} else {
continue;
}
} else {
continue;
}
}
}
if (apnContext.isConnectable()) {
log("isConnectable() call trySetupData");
apnContext.setReason(reason);
trySetupData(apnContext, waitingApns);
}
}
}
6.4 、开始拨号工作trySetupData
trySetupData（）函数主要做两件事
1、判断APN状态是DctConstants.State.IDLE 的时候调用buildWaitingApns 构建拨号APN列表 并通过apnContext.setWaitingApns(waitingApns)将waitingApns列表设置到apnContext 中。
2、调用setupData(apnContext, radioTech)使用apn进行拨号连接。
if (apnContext.getState() == DctConstants.State.IDLE) {
if (waitingApns == null) {
waitingApns = buildWaitingApns(apnContext.getApnType(), radioTech);
}
if (waitingApns.isEmpty()) {
notifyNoData(DcFailCause.MISSING_UNKNOWN_APN, apnContext);
notifyOffApnsOfAvailability(apnContext.getReason());
String str = “trySetupData: X No APN found retValue=false”;
if (DBG) log(str);
apnContext.requestLog(str);
return false;
} else {
apnContext.setWaitingApns(waitingApns);
isReconnectedFinsh = false;
if (DBG) {
log (“trySetupData: Create from mAllApnSettings : "
+ apnListToString(mAllApnSettings)+” isReconnectedFinsh "+isReconnectedFinsh);
}
}
}
6.5、buildWaitingApns分析
buildWaitingApns函数新建的一个WaitingApns集合的APN来源有两个：
1、getPreferredApn()从文件存储中去获取之前选中过的APN，如果该APN 的Type类型为上网的类型并且numeric 国家码和SIM卡的国家码一致，就将此apn添加到apn拨号列表中，如果不同就清除保存的preferenceAPN为-1，这样可以防止换了SIM卡的情况。当然恢复出厂设置或者刷机第一次起来的时候这个preferenceAPN也是NULL的，因为没有设置过。
2、从mAllApnSettings 中遍历选中APN的type 为拨号相同type的APN 添加到拨号列表中，mAllApnSettings 自动从代码里面搜一下可以看到它是从数据库中搜索而来的，根据MMC国家码来判断如果和SIM卡相同就添加到mAllApnSettings 列表中，这样mAllApnSettings 列表中实际上是有很多不同type 比如上网，短信等等类型的apn。
/**
* Build a list of APNs to be used to create PDP's.
*
* @param requestedApnType
* @return waitingApns list to be used to create PDP
* error when waitingApns.isEmpty()
*/
private ArrayList<ApnSetting> buildWaitingApns(String requestedApnType, int radioTech) {
if (DBG) log("buildWaitingApns: E requestedApnType=" + requestedApnType);
ArrayList<ApnSetting> apnList = new ArrayList<ApnSetting>();
if (requestedApnType.equals(PhoneConstants.APN_TYPE_DUN)) {
ApnSetting dun = fetchDunApn();
if (dun != null) {
apnList.add(dun);
if (DBG) log("buildWaitingApns: X added APN_TYPE_DUN apnList=" + apnList);
return apnList;
}
}
IccRecords r = mIccRecords.get();
String operator = (r != null) ? r.getOperatorNumeric() : "";
// This is a workaround for a bug (7305641) where we don't failover to other
// suitable APNs if our preferred APN fails. On prepaid ATT sims we need to
// failover to a provisioning APN, but once we've used their default data
// connection we are locked to it for life. This change allows ATT devices
// to say they don't want to use preferred at all.
boolean usePreferred = true;
try {
usePreferred = ! mPhone.getContext().getResources().getBoolean(com.android.
internal.R.bool.config_dontPreferApn);
} catch (Resources.NotFoundException e) {
if (DBG) log("buildWaitingApns: usePreferred NotFoundException set to true");
usePreferred = true;
}
if (usePreferred) {
//查询数据库看是否有志气设置的已经选中过的APN
mPreferredApn = getPreferredApn();
}
if (DBG) {
log("buildWaitingApns: usePreferred=" + usePreferred
+ " canSetPreferApn=" + mCanSetPreferApn
+ " mPreferredApn=" + mPreferredApn
+ " operator=" + operator + " radioTech=" + radioTech
+ " IccRecords r=" + r);
}
if (usePreferred && mCanSetPreferApn && mPreferredApn != null &&
mPreferredApn.canHandleType(requestedApnType)) {
if (DBG) {
log("buildWaitingApns: Preferred APN:" + operator + ":"
+ mPreferredApn.numeric + ":" + mPreferredApn);
}
if (mPreferredApn.numeric.equals(operator)) {
if (ServiceState.bitmaskHasTech(mPreferredApn.bearerBitmask, radioTech)) {
apnList.add(mPreferredApn);
if (DBG) log("buildWaitingApns: X added preferred apnList=" + apnList);
return apnList;
} else {
if (DBG) log("buildWaitingApns: no preferred APN");
setPreferredApn(-1);
mPreferredApn = null;
}
} else {
if (DBG) log("buildWaitingApns: no preferred APN");
setPreferredApn(-1);
mPreferredApn = null;
}
}
if (mAllApnSettings != null) {
if (DBG) log("buildWaitingApns: mAllApnSettings=" + mAllApnSettings);
for (ApnSetting apn : mAllApnSettings) {
if (apn.canHandleType(requestedApnType)) {
if (ServiceState.bitmaskHasTech(apn.bearerBitmask, radioTech)) {
if (DBG) log("buildWaitingApns: adding apn=" + apn);
apnList.add(apn);
} else {
if (DBG) {
log("buildWaitingApns: bearerBitmask:" + apn.bearerBitmask + " does " +
"not include radioTech:" + radioTech);
}
}
} else if (DBG) {
log("buildWaitingApns: couldn't handle requested ApnType="
+ requestedApnType);
}
}
} else {
loge("mAllApnSettings is null!");
}
if (DBG) log("buildWaitingApns: " + apnList.size() + " APNs in the list: " + apnList);
return apnList;
}
6.6 、apnContext.setWaitingApns(waitingApns)
setWaitingApns是RetryManager.java的一个方法，代码路径是：frameworks/opt/telephony/src/java/com/android/internal/telephony/RetryManager.java
设置apnContext的waitingApns 时会配置RetryManager的config 信息，debug 版本可以通过SystemProperties.get(“test.data_retry_config”)配置测试，我们这里用默认的SIM配置。包含apn重试最大次数，apn重试延迟时间等等，和获取当前重试apn列表的mCurrentApnIndex 索引，在每次设置setWaitingApns都会将这些config信息全部reset。这就意味着如果设置一次setWaitingApns，所有的重试策略都会重置，apn列表选择重新开始。这里其实是有点问题的，后面再说。
private void reset() {
mMaxRetryCount = 0;
mRetryCount = 0;
mCurrentApnIndex = -1;
mSameApnRetryCount = 0;
mModemSuggestedDelay = NO_SUGGESTED_RETRY_DELAY;
mRetryArray.clear();
}
6.7、setupData（）拨号函数。
1、setupData拨号的时候首先通过apnSetting = apnContext.getNextApnSetting() 从apnContext中获取拨号列表中的apn。
2、这里有几种情况下会替换apnContext 中的apnSetting:
1>还有dataConnection没有断开，直接dcacApnSetting = dcac.getApnSettingSync()获取dcac的apnSetting 替换用来拨号
2> dcac断开的情况下，如果isOnlySingleDcAllowed或者isHigherPriorityApnContextActive ，就是如果是只允许单dcac模式或者有更高优先级的apnContext也是不用getNextApnSetting得到的apnSetting直接return返回停止拨号。
3>上述情况都不满足的情况下会cleanUpAllConnections断开 当前所以apnContext连接，如果是不是IDLE或者FAILED状态则表示cleanUpAllConnections没有完成清除，这种情况下也是直接return停止拨号操作。
3、以上判断走完后就会将当前的apnContext设置为参数通过EVENT_DATA_SETUP_COMPLETE 发送给RILD最终完成拨号。
Message msg = obtainMessage();
msg.what = DctConstants.EVENT_DATA_SETUP_COMPLETE;
msg.obj = new Pair<ApnContext, Integer>(apnContext, generation);
dcac.bringUp(apnContext, profileId, radioTech, msg, generation);
private boolean setupData(ApnContext apnContext, int radioTech) {
if (DBG) log("setupData: apnContext=" + apnContext);
apnContext.requestLog("setupData");
ApnSetting apnSetting;
DcAsyncChannel dcac = null;
apnSetting = apnContext.getNextApnSetting();
log("try this apnSetting:"+apnSetting);
if (apnSetting == null) {
if (DBG) log("setupData: return for no apn found!");
return false;
}
int profileId = apnSetting.profileId;
if (profileId == 0) {
profileId = getApnProfileID(apnContext.getApnType());
}
// On CDMA, if we're explicitly asking for DUN, we need have
// a dun-profiled connection so we can't share an existing one
// On GSM/LTE we can share existing apn connections provided they support
// this type.
if (apnContext.getApnType() != PhoneConstants.APN_TYPE_DUN ||
teardownForDun() == false) {
dcac = checkForCompatibleConnectedApnContext(apnContext);
if (dcac != null) {
// Get the dcacApnSetting for the connection we want to share.
ApnSetting dcacApnSetting = dcac.getApnSettingSync();
if (dcacApnSetting != null) {
// Setting is good, so use it.
log("dcac still connect, dcac.getApnSettingSync():"+dcacApnSetting);
apnSetting = dcacApnSetting;
}
}
}
if (dcac == null) {
if (isOnlySingleDcAllowed(radioTech)) {
if (isHigherPriorityApnContextActive(apnContext)) {
if (DBG) {
log("setupData: Higher priority ApnContext active. Ignoring call");
}
return false;
}
// Only lower priority calls left. Disconnect them all in this single PDP case
// so that we can bring up the requested higher priority call (once we receive
// response for deactivate request for the calls we are about to disconnect
if (cleanUpAllConnections(true, Phone.REASON_SINGLE_PDN_ARBITRATION)) {
// If any call actually requested to be disconnected, means we can't
// bring up this connection yet as we need to wait for those data calls
// to be disconnected.
if (DBG) log("setupData: Some calls are disconnecting first. Wait and retry");
return false;
}
// No other calls are active, so proceed
if (DBG) log("setupData: Single pdp. Continue setting up data call.");
}
dcac = findFreeDataConnection();
if (dcac == null) {
dcac = createDataConnection();
}
if (dcac == null) {
if (DBG) log("setupData: No free DataConnection and couldn't create one, WEIRD");
return false;
}
}
final int generation = apnContext.incAndGetConnectionGeneration();
if (DBG) {
log("setupData: dcac=" + dcac + " apnSetting=" + apnSetting + " gen#=" + generation);
}
apnContext.setDataConnectionAc(dcac);
apnContext.setApnSetting(apnSetting);
apnContext.setState(DctConstants.State.CONNECTING);
mPhone.notifyDataConnection(apnContext.getReason(), apnContext.getApnType());
Message msg = obtainMessage();
msg.what = DctConstants.EVENT_DATA_SETUP_COMPLETE;
msg.obj = new Pair<ApnContext, Integer>(apnContext, generation);
dcac.bringUp(apnContext, profileId, radioTech, msg, generation);
if (DBG) log("setupData: initing!");
return true;
}
private void setInitialAttachApn() {
ApnSetting iaApnSetting = null;
ApnSetting defaultApnSetting = null;
ApnSetting firstApnSetting = null;
log("setInitialApn: E mPreferredApn=" + mPreferredApn);
if (mAllApnSettings != null && !mAllApnSettings.isEmpty()) {
firstApnSetting = mAllApnSettings.get(0);
log("setInitialApn: firstApnSetting=" + firstApnSetting);
// Search for Initial APN setting and the first apn that can handle default
for (ApnSetting apn : mAllApnSettings) {
// Can't use apn.canHandleType(), as that returns true for APNs that have no type.
if (ArrayUtils.contains(apn.types, PhoneConstants.APN_TYPE_IA) &&
apn.carrierEnabled) {
// The Initial Attach APN is highest priority so use it if there is one
log("setInitialApn: iaApnSetting=" + apn);
iaApnSetting = apn;
break;
} else if ((defaultApnSetting == null)
&& (apn.canHandleType(PhoneConstants.APN_TYPE_DEFAULT))) {
// Use the first default apn if no better choice
log("setInitialApn: defaultApnSetting=" + apn);
defaultApnSetting = apn;
}
}
}
// The priority of apn candidates from highest to lowest is:
// 1) APN_TYPE_IA (Initial Attach)
// 2) mPreferredApn, i.e. the current preferred apn
// 3) The first apn that than handle APN_TYPE_DEFAULT
// 4) The first APN we can find.
ApnSetting initialAttachApnSetting = null;
if (iaApnSetting != null) {
if (DBG) log("setInitialAttachApn: using iaApnSetting");
initialAttachApnSetting = iaApnSetting;
} else if (mPreferredApn != null) {
if (DBG) log("setInitialAttachApn: using mPreferredApn");
initialAttachApnSetting = mPreferredApn;
} else if (defaultApnSetting != null) {
if (DBG) log("setInitialAttachApn: using defaultApnSetting");
initialAttachApnSetting = defaultApnSetting;
} else if (firstApnSetting != null) {
if (DBG) log("setInitialAttachApn: using firstApnSetting");
initialAttachApnSetting = firstApnSetting;
}
if (initialAttachApnSetting == null) {
if (DBG) log("setInitialAttachApn: X There in no available apn");
} else {
if (DBG) log("setInitialAttachApn: X selected Apn=" + initialAttachApnSetting);
mPhone.mCi.setInitialAttachApn(initialAttachApnSetting.apn,
initialAttachApnSetting.protocol, initialAttachApnSetting.authType,
initialAttachApnSetting.user, initialAttachApnSetting.password, null);
}
}
7、拨号完成，4G网络可以正常使用
framework拨号设置完成以后，RILD开始拨号分配ip 这些链路信息成功后会返回给DataConnection EVENT_SETUP_DATA_CONNECTION_DONE事件，同时DataConnection更新自己的networkAgent通知ConnectivityService改变网络状态为Connected,到这里整个拨号流程就全部结束了.
代码路径：frameworks/opt/telephony/src/java/com/android/internal/telephony/dataconnection/DataConnection.java
private class DcActivatingState extends State {
@Override
public boolean processMessage(Message msg) {
boolean retVal;
AsyncResult ar;
ConnectionParams cp;
if (DBG) log("DcActivatingState: msg=" + msgToString(msg));
switch (msg.what) {
case EVENT_DATA_CONNECTION_DRS_OR_RAT_CHANGED:
case EVENT_CONNECT:
// Activating can't process until we're done.
deferMessage(msg);
retVal = HANDLED;
break;
case EVENT_SETUP_DATA_CONNECTION_DONE:
ar = (AsyncResult) msg.obj;
cp = (ConnectionParams) ar.userObj;
DataCallResponse.SetupResult result = onSetupConnectionCompleted(ar);
if (result != DataCallResponse.SetupResult.ERR_Stale) {
if (mConnectionParams != cp) {
loge("DcActivatingState: WEIRD mConnectionsParams:"+ mConnectionParams
+ " != cp:" + cp);
}
}
if (DBG) {
log("DcActivatingState onSetupConnectionCompleted result=" + result
+ " dc=" + DataConnection.this);
}
if (cp.mApnContext != null) {
cp.mApnContext.requestLog("onSetupConnectionCompleted result=" + result);
}
5、结尾
6.6和6.7中提到的拨号的问题：
我们看一下6.6中 trySetupData 函数里面判断只要是当前apnContext状态为DctConstants.State.IDLE就会去 buildWaitingApns并且设置到apnContext 中，前面我们也提到
apnContext中每次设置setWaitingApns的时候都会重置currentApnSettingIndex脚本，这样每次重试的时候都是重头开始去apn拨号，而且6.7中有很多种情况会替换到从apnContext中取到的apnSetting,比如当前dcac没有断开连接，当前连接正在断开等等状态都会导致拨号跳过，好家伙，这么坑的漏洞就导致客户那边出现的每次拨号都是使用第一个APN拨号，列表的其他apn没有用到，因为都跳过了，导致拨号一直失败，自然设置界面的apn列表当然没有apn被连接上。
这个问题的解决办法就是尽量不要多次调用apnContext.setWaitingApns防止RetryManager的config参数被重置，另外setUpData拨号函数里面如果retrun跳过当前apn的话记录currentIndex这样下次还是使用这个apn拨号，这样就可以保证apn列表循环尝试了。
if (apnContext.getState() == DctConstants.State.IDLE) {
if (waitingApns == null) {
waitingApns = buildWaitingApns(apnContext.getApnType(), radioTech);
}
if (waitingApns.isEmpty()) {
notifyNoData(DcFailCause.MISSING_UNKNOWN_APN, apnContext);
notifyOffApnsOfAvailability(apnContext.getReason());
String str = “trySetupData: X No APN found retValue=false”;
if (DBG) log(str);
apnContext.requestLog(str);
return false;
} else {
apnContext.setWaitingApns(waitingApns);
}