Android4.4 RIL短信接收流程分析

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)); 
    }
    ... ...
}

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;
}

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;
}

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);
}

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;
        }
    }

    ... ...
}

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: +8613800755500 */
    }
    
    ... ...
    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: +861371533xxxx */                                                                                  
                + 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' */
    ... ...
} 

mgsmsmsregistrant
    .notifyregistrant(new asyncresult(null, sms, null));                             /* 把sms转成object类型 */

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;
    }
    ... ...
}

public abstract class basecommands implements commandsinterface {
    ... ...
    
    @override                                                                                                                                                
    public void setonnewgsmsms(handler h, int what, object obj) {     /* mgsmsmsregistrant.notifyregistrant(new asyncresult(null, sms, null))中的mgsmsmsregistrant是在这里创建的 */                                                                                       
        mgsmsmsregistrant = new registrant (h, what, obj);                                                                                                   
    }
    
    ... ...
}

public class registrant                                                                                                                                      
{ 
    public
    registrant(handler h, int what, 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, sms, 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(), event_new_sms, null);的gethandler() */
        }
    }

    ... ...
}  

public final class imssmsdispatcher extends smsdispatcher {
    ... ...
    mgsminboundsmshandler = gsminboundsmshandler.makeinboundsmshandler(phone.getcontext(),         /* 获取mgsminboundsmshandler，并启动状态机 */
            storagemonitor, phone);  
    ... ...
}

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(), event_new_sms, 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,
            smsstoragemonitor storagemonitor, phonebase phone) {
        gsminboundsmshandler handler = new gsminboundsmshandler(context, storagemonitor, 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;
    }

    ... ...
}

public abstract class inboundsmshandler extends statemachine {
    ... ...
    protected inboundsmshandler(string name, context context, smsstoragemonitor storagemonitor,
            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);
    ... ...
}

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 */

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