详解Android4.4 RIL短信接收流程分析

最近有客户反馈Android接收不到短信，于是一头扎进RIL里面找原因。最后发现不是RIL的问题，而是BC72上报
短信的格式不对，AT+CNMA=1无作用等几个小问题导致的。尽管问题不在RIL，但总算把RIL短信接收流程搞清楚了。

接收到新信息的log：

D/ATC ( 1269): AT< +CMT:,27
D/ATC ( 1268): AT< 0891683108705505F0040d91683117358313f500009101329154922307ea31da2c36a301
D/RILJ ( 1792): [UNSL]< UNSOL_RESPONSE_NEW_SMS
D/SmsMessage( 1792): SMS SC address: [phone]
V/SmsMessage( 1792): SMS originating address: [phone]
V/SmsMessage( 1792): SMS TP-PID:0 data coding scheme: 0
D/SmsMessage( 1792): SMS SC timestamp: 1571831129000
V/SmsMessage( 1792): SMS message body (raw): 'jchfbfh'
D/GsmInboundSmsHandler( 1776): Idle state processing message type 1
D/GsmInboundSmsHandler( 1776): acquired wakelock,leaving Idle state
D/GsmInboundSmsHandler( 1776): entering Delivering state
D/GsmInboundSmsHandler( 1776): URI of new row -> content://raw/3
D/RILJ ( 1775): [3706]> SMS_ACKNOWLEDGE true 0
D/RILC ( 1254): onRequest: SMS_ACKNOWLEDGE
D/ATC ( 1254): AT> AT+CNMA=1
D/ATC ( 1254): AT< OK
D/RILJ ( 1775): [3706]< SMS_ACKNOWLEDGE
D/GsmInboundSmsHandler( 1775): Delivering SMS to: com.android.mms com.android.mms.transaction.PrivilegedSmsReceiver
E/GsmInboundSmsHandler( 1775): unexpected BroadcastReceiver action: android.provider.Telephony.SMS_RECEIVED
D/GsmInboundSmsHandler( 1775): successful broadcast,deleting from raw table.
D/SmsMessage( 2124): SMS SC address: [phone]
D/GsmInboundSmsHandler( 1775): Deleted 1 rows from raw table.
D/GsmInboundSmsHandler( 1775): ordered broadcast completed in: 276 ms
D/GsmInboundSmsHandler( 1775): leaving Delivering state
D/GsmInboundSmsHandler( 1775): entering Delivering state
D/GsmInboundSmsHandler( 1775): leaving Delivering state
D/GsmInboundSmsHandler( 1775): entering Idle state
V/SmsMessage( 2124): SMS originating address: [phone]
V/SmsMessage( 2124): SMS TP-PID:0 data coding scheme: 0
D/SmsMessage( 2124): SMS SC timestamp: 1572253549000
V/SmsMessage( 2124): SMS message body (raw): 'jchfbfh'
D/GsmInboundSmsHandler( 1775): Idle state processing message type 5
D/GsmInboundSmsHandler( 1775): mWakeLock released

一、短信接收

1. vendor ril接收到modem上报的短信息

hardware/ril/reference-ril/reference-ril.c
static void onUnsolicited (const char *s,const char *sms_pdu)
{
 ... ...
 if (strStartsWith(s,"+CMT:")) {
  RIL_onUnsolicitedResponse (
   RIL_UNSOL_RESPONSE_NEW_SMS,/* 上报UNSOL_RESPONSE_NEW_SMS消息 */
   sms_pdu,strlen(sms_pdu));
 }
 ... ...
}

2. RILD把短信息发送到RILJ

hardware/ril/libril/ril.cpp
extern "C"
void RIL_onUnsolicitedResponse(int unsolResponse,void *data,size_t datalen)
{
 ... ...
 unsolResponseIndex = unsolResponse - RIL_UNSOL_RESPONSE_BASE; /* 找出消息在s_unsolResponses[]的索引 */
 ... ...
 switch (s_unsolResponses[unsolResponseIndex].wakeType) {   /* 禁止进入休眠 */
  case WAKE_PARTIAL:
   grabPartialWakeLock();
   shouldScheduleTimeout = true;
  break;
  ... ...
 }
 ... ...
 ret = s_unsolResponses[unsolResponseIndex]      /* 调用消息处理函数responseString() */
    .responseFunction(p,data,datalen);
 ... ...
 ret = sendResponse(p);           /* 发送Parcel中的信息内容到服务端RILJ */
}
static UnsolResponseInfo s_unsolResponses[] = {
... ...
/* 消息对应的消息处理函数，新信息到来会唤醒系统 */
{RIL_UNSOL_RESPONSE_NEW_SMS,responseString,WAKE_PARTIAL},... ...
}；
static int responseString(Parcel &p,void *response,size_t responselen) {
 /* one string only */
 startResponse;
 appendPrintBuf("%s%s",printBuf,(char*)response);
 closeResponse;
 writeStringToParcel(p,(const char *)response);     /* 把字符串格式的信息存到Parcel容器中 */
 return 0;
}

二、解析短信息

1. RILJ获取短信息

frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
private void
processUnsolicited (Parcel p) {
 ... ...
 case RIL_UNSOL_RESPONSE_NEW_SMS: ret = responseString(p); break;
 ... ...
 switch(response) {
  ... ...
  case RIL_UNSOL_RESPONSE_NEW_SMS: {
   if (RILJ_LOGD) unsljLog(response);      /* 参考log：[UNSL]< UNSOL_RESPONSE_NEW_SMS */
   // FIXME this should move up a layer
   String a[] = new String[2];
   a[1] = (String)ret;
   SmsMessage sms;
   sms = SmsMessage.newFromCMT(a);       /* 解析PDU格式的短信息 */
   if (mGsmSmsRegistrant != null) {
    mGsmSmsRegistrant
     .notifyRegistrant(new AsyncResult(null,sms,null));
   }
   break;
  }
  ... ...
 }
 ... ...
}
private Object
responseString(Parcel p) {
 String response;
 response = p.readString();               /* 信息内容转换成Object */
 return response;
}

2. 解析短信息

SmsMessage.newFromCMT(a);根据import android.telephony.SmsMessage，得知代码路径：

frameworks/opt/telephony/src/java/android/telephony/SmsMessage.java
public static SmsMessage newFromCMT(String[] lines) {
 // received SMS in 3GPP format
 SmsMessageBase wrappedMessage =
   com.android.internal.telephony.gsm.SmsMessage.newFromCMT(lines);  /* 是对另一个newFromCMT的封装，因为有gsm和cdma两种短信，
                     * 即cdma中也有newFromCMT，根据情况按需选择
                     */
 return new SmsMessage(wrappedMessage);
}
  com.android.internal.telephony.gsm.SmsMessage.newFromCMT(lines)的实现在
frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/SmsMessage.java
public class SmsMessage extends SmsMessageBase {
 ... ...
 public static SmsMessage newFromCMT(String[] lines) {
  try {
   SmsMessage msg = new SmsMessage();
   msg.parsePdu(IccUtils.hexStringToBytes(lines[1]));    /* 解析PDU短信 */
   return msg;
  } catch (RuntimeException ex) {
   Rlog.e(LOG_TAG,"SMS PDU parsing failed: ",ex);
   return null;
  }
 }
 ... ...
}
  IccUtils.hexStringToBytes(lines[1])把十六进制的字符串转换成字节数组msg.parsePdu()解析这个数组的内容，最后获得短信内容
frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/SmsMessage.java
private void parsePdu(byte[] pdu) {
 ... ...
 mScAddress = p.getSCAddress();
 if (mScAddress != null) {
  if (VDBG) Rlog.d(LOG_TAG,"SMS SC address: " + mScAddress);   /* 参考log：SMS SC address: [phone] */
 }
 ... ...
 mMti = firstByte & 0x3;
 switch (mMti) {
  ... ...
   case 3: //GSM 03.40 9.2.3.1: MTI == 3 is Reserved.
     //This should be processed in the same way as MTI == 0 (Deliver)
    parseSmsDeliver(p,firstByte);         /* 对短信类型为Deliver的短信进行解析 */
    break;
   ... ...
  }
 ... ...
}
private void parseSmsDeliver(PduParser p,int firstByte) {
 ... ...
 mOriginatingAddress = p.getAddress();
 if (mOriginatingAddress != null) {
  if (VDBG) Rlog.v(LOG_TAG,"SMS originating address: "    /* 参考log: SMS originating address: [phone]xxxx */
    + mOriginatingAddress.address);
 }
 ... ...
 mProtocolIdentifier = p.getByte();
 // TP-Data-Coding-Scheme
 // see TS 23.038
 mDataCodingScheme = p.getByte();
 if (VDBG) {
  Rlog.v(LOG_TAG,"SMS TP-PID:" + mProtocolIdentifier
    + " data coding scheme: " + mDataCodingScheme);    /* 参考log: SMS TP-PID:0 data coding scheme: 0 */
 }
 mScTimeMillis = p.getSCTimestampMillis();
 if (VDBG) Rlog.d(LOG_TAG,"SMS SC timestamp: " + mScTimeMillis);   /* 参考log：SMS SC timestamp: 1571831129000 */
 boolean hasUserDataHeader = (firstByte & 0x40) == 0x40;
 parseUserData(p,hasUserDataHeader);          /* 解析信息有效内容 */
 ... ...
}
private void parseUserData(PduParser p,boolean hasUserDataHeader) {
 ... ...
 if (VDBG) Rlog.v(LOG_TAG,"SMS message body (raw): '" + mMessageBody + "'"); /* 短信内容，参考log: SMS message body (raw): 'jchfbfh' */
 ... ...
} 

三、处理短信息  

对用户有效的短信内容，最终保存在类型为String的mMessageBody变量中，该变量属于SmsMessageBase抽象类，而
SmsMessage继承于SmsMessageBase。
        回到前面frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java中processUnsolicited(),
sms = SmsMessage.newFromCMT(a);解析完短信息后，返回一个SmsMessage并通知上层应用。

frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
mGsmSmsRegistrant
 .notifyRegistrant(new AsyncResult(null,null));        /* 把sms转成Object类型 */
frameworks/base/core/java/android/os/AsyncResult.java
public class AsyncResult
{
 ... ...
 /** please note,this sets m.obj to be this */
 public
 AsyncResult (Object uo,Object r,Throwable ex)
 {
  userObj = uo;
  result = r;
  exception = ex;
 }
 ... ...
}

根据mGsmSmsRegistrant.notifyRegistrant(new AsyncResult(null,null));找到mGsmSmsRegistrant注册的代码：

frameworks/opt/telephony/src/java/com/android/internal/telephony/BaseCommands.java
public abstract class BaseCommands implements CommandsInterface {
 ... ...
 @Override
 public void setOnNewGsmSms(Handler h,int what,Object obj) {  /* mGsmSmsRegistrant.notifyRegistrant(new AsyncResult(null,null))中的mGsmSmsRegistrant是在这里创建的 */
  mGsmSmsRegistrant = new Registrant (h,what,obj);
 }
 ... ...
} 

封装消息EVENT_NEW_SMS消息

frameworks/base/core/java/android/os/Registrant.java
public class Registrant
{
 public
 Registrant(Handler h,Object obj)      /* 传入需要处理消息为what的事件处理Handler h，obj为事件内容，参考phone.mCi.setOnNewGsmSms(getHandler(),EVENT_NEW_SMS,null); */
 {
  refH = new WeakReference(h);
  this.what = what;
  userObj = obj;
 }
 ... ...
 /**
  * This makes a copy of @param ar
  */
 public void
 notifyRegistrant(AsyncResult ar)         /* 参考mGsmSmsRegistrant.notifyRegistrant(new AsyncResult(null,null)) */
 {
  internalNotifyRegistrant (ar.result,ar.exception);   /* ar.result为sms */
 }
 /*package*/ void
 internalNotifyRegistrant (Object result,Throwable exception)  /* internalNotifyRegistrant (sms,Throwable exception) */
 {
  Handler h = getHandler();
  if (h == null) {
   clear();
  } else {
   Message msg = Message.obtain();       /* 创建一个消息 */
   msg.what = what;           /* 消息类型EVENT_NEW_SMS */
   msg.obj = new AsyncResult(userObj,result,exception); /* 消息内容sms */
   h.sendMessage(msg);          /* 发送消息到注册了这个消息的Handler，参考phone.mCi.setOnNewGsmSms(getHandler(),null);的getHandler() */
  }
 }
 ... ...
} 

然而BaseCommands是一个抽象类，实现了CommandsInterface中的setOnNewGsmSms接口，这个接口由GsmInboundSmsHandler调用
（phone.mCi.setOnNewGsmSms(getHandler(),null)），也就是说GsmInboundSmsHandler的getHandler()是EVENT_NEW_SMS
的监听者，也就是说frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java中mGsmSmsRegistrant.notifyRegistrant(new AsyncResult(null,null))
调用之后，会触发GsmInboundSmsHandler中getHandler()的Handler对EVENT_NEW_SMS消息进行解析。这个Handler肯定是GsmInboundSmsHandler
实例化的对象中的，这个对象在什么时候，在哪里创建的，暂且不管。我们只管EVENT_NEW_SMS这个消息从哪里来，然后到哪里去
就行了。

./frameworks/opt/telephony/src/java/com/android/internal/telephony/ImsSMSDispatcher.java
public final class ImsSMSDispatcher extends SMSDispatcher {
 ... ...
 mGsmInboundSmsHandler = GsmInboundSmsHandler.makeInboundSmsHandler(phone.getContext(),/* 获取mGsmInboundSmsHandler，并启动状态机 */
   storageMonitor,phone);
 ... ...
}
./frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/GsmInboundSmsHandler.java
public class GsmInboundSmsHandler extends InboundSmsHandler {
 ... ...
 /**
  * Create a new GSM inbound SMS handler.
  */
 private GsmInboundSmsHandler(Context context,SmsStorageMonitor storageMonitor,PhoneBase phone) {
  super("GsmInboundSmsHandler",context,storageMonitor,phone,/* 构造GsmInboundSmsHandler时，通过super()调用InboundSmsHandler的构造函数 */
    GsmCellBroadcastHandler.makeGsmCellBroadcastHandler(context,phone));
  phone.mCi.setOnNewGsmSms(getHandler(),null);        /* 注册EVENT_NEW_SMS消息 */
  mDataDownloadHandler = new UsimDataDownloadHandler(phone.mCi);
 }
 ... ...
 /**
  * Wait for state machine to enter startup state. We can't send any messages until then.
  */
 public static GsmInboundSmsHandler makeInboundSmsHandler(Context context,PhoneBase phone) {
  GsmInboundSmsHandler handler = new GsmInboundSmsHandler(context,phone); /* 实例化GsmInboundSmsHandler */
  handler.start();                   /* 抽象类InboundSmsHandler继承与StateMachine，而GsmInboundSmsHandler继承于InboundSmsHandler，
                         * GsmInboundSmsHandler调用启动状态机方法start()
                         */
  return handler;
 }
 ... ...
}
./frameworks/opt/telephony/src/java/com/android/internal/telephony/InboundSmsHandler.java
public abstract class InboundSmsHandler extends StateMachine {
 ... ...
 protected InboundSmsHandler(String name,Context context,PhoneBase phone,CellBroadcastHandler cellBroadcastHandler) {
  ... ...
  addState(mDefaultState);                 /* 构造InboundSmsHandler时，添加状态机的状态 */
  addState(mStartupState,mDefaultState);
  addState(mIdleState,mDefaultState);
  addState(mDeliveringState,mDefaultState);
  addState(mWaitingState,mDeliveringState);
  setInitialState(mStartupState);               /* 初始化状态机 */
  if (DBG) log("created InboundSmsHandler");
 }
 ... ...
 class IdleState extends State {
  @Override
  public void enter() {
   if (DBG) log("entering Idle state");
   sendMessageDelayed(EVENT_RELEASE_WAKELOCK,WAKELOCK_TIMEOUT);
  }
  @Override
  public void exit() {
   mWakeLock.acquire();
   if (DBG) log("acquired wakelock,leaving Idle state");
  }
  @Override
  public boolean processMessage(Message msg) {
   if (DBG) log("Idle state processing message type " + msg.what);
   switch (msg.what) {
    case EVENT_NEW_SMS:                /* 空闲时，接收到短信 */
    case EVENT_BROADCAST_SMS:
     deferMessage(msg);
     transitionTo(mDeliveringState);            /* 转到mDeliveringState */
     return HANDLED;
    ... ...
   }
  }
 }
  ... ...
 class DeliveringState extends State {               /* 转到mDeliveringState状态 */
  @Override
  public void enter() {
   if (DBG) log("entering Delivering state");
  }
  @Override
  public void exit() {
   if (DBG) log("leaving Delivering state");
  }
  @Override
  public boolean processMessage(Message msg) {
   switch (msg.what) {
    case EVENT_NEW_SMS:
     // handle new SMS from RIL
     handleNewSms((AsyncResult) msg.obj);           /* 处理新SMS */
     sendMessage(EVENT_RETURN_TO_IDLE);            /* 处理完回到空闲状态 */
     return HANDLED;
    ... ...
   }
  }
   ... ...
 }
}
void handleNewSms(AsyncResult ar) {
 ... ...
 SmsMessage sms = (SmsMessage) ar.result;
 result = dispatchMessage(sms.mWrappedSmsMessage);
 ... ...
}
public int dispatchMessage(SmsMessageBase smsb) {
 ... ...
 return dispatchMessageRadioSpecific(smsb);
 ... ...
}

通过以上流程可以了解到，当状态机接收到SMS后，对消息进行分发，针对type zero,SMS-PP data download,
和3GPP/CPHS MWI type SMS判断，如果是Normal SMS messages，则调用dispatchNormalMessage(smsb)，然后创建
一个InboundSmsTracker对象，把信息保存到raw table，然后在通过sendMessage(EVENT_BROADCAST_SMS,tracker)把消息广播出去。

./frameworks/opt/telephony/src/java/com/android/internal/telephony/InboundSmsHandler.java 

class DeliveringState extends State {
 ... ...
 public boolean processMessage(Message msg) {
  switch (msg.what) {
   ... ...
   case EVENT_BROADCAST_SMS:               /* 接收到EVENT_BROADCAST_SMS消息并处理 */
    // if any broadcasts were sent,transition to waiting state
    if (processMessagePart((InboundSmsTracker) msg.obj)) {
     transitionTo(mWaitingState);
    }
    return HANDLED;
   ... ...
  }
 }
 ... ...

}

boolean processMessagePart(InboundSmsTracker tracker) {
 ... ...
 BroadcastReceiver resultReceiver = new SmsBroadcastReceiver(tracker);     /* 创建一个广播接收者，用来处理短信广播的结果 */
 ... ...
 intent = new Intent(Intents.SMS_DELIVER_ACTION);           /* 设置当前intent的action为SMS_DELIVER_ACTION */

 // Direct the intent to only the default SMS app. If we can't find a default SMS app
 // then sent it to all broadcast receivers.
 ComponentName componentName = SmsApplication.getDefaultSmsApplication(mContext,true); /* 这个action只会发送给carrier app，而且carrier app可以通过set result为RESULT_CANCELED来终止这个广播 */
 if (componentName != null) {
  // Deliver SMS message only to this receiver
  intent.setComponent(componentName);
  log("Delivering SMS to: " + componentName.getPackageName() +
    " " + componentName.getClassName());
 }
 ... ...
 dispatchIntent(intent,android.Manifest.permission.RECEIVE_SMS,/* 广播intent */
    AppOpsManager.OP_RECEIVE_SMS,resultReceiver);
 ... ...
}

private final class SmsBroadcastReceiver extends BroadcastReceiver {
 ... ...
 public void onReceive(Context context,Intent intent) {
  ... ...
  // Now that the intents have been deleted we can clean up the PDU data.
  if (!Intents.DATA_SMS_RECEIVED_ACTION.equals(action)
    && !Intents.DATA_SMS_RECEIVED_ACTION.equals(action)
    && !Intents.WAP_PUSH_RECEIVED_ACTION.equals(action)) {
   loge("unexpected BroadcastReceiver action: " + action);
  }

  int rc = getResultCode();
  if ((rc != Activity.RESULT_OK) && (rc != Intents.RESULT_SMS_HANDLED)) {
   loge("a broadcast receiver set the result code to " + rc
     + ",deleting from raw table anyway!");
  } else if (DBG) {
   log("successful broadcast,deleting from raw table.");
  }

  deleteFromRawTable(mDeleteWhere,mDeleteWhereArgs);
  sendMessage(EVENT_BROADCAST_COMPLETE);            /* 成功广播 */

  ... ...
 }
 ... ...
}

到这里，在应用层注册具有Intents.SMS_RECEIVED_ACTION这样action的广播，就可以获取到短信了。

总结

以上所述是小编给大家介绍的Android4.4 RIL短信接收流程分析,希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！
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