C++版的网络数据包解析策略(升级版)

一、数据包格式形如下图

二、代码

int ReceiveFromRemoteEndPoint()

{

    int nPackageDataLength = ;

    char *szPackageCleaner = NULL;

    char *szPackageIterator = NULL;

    do

    {

        char *szReceiveArray = new char[RECEIVED_BUFFER_LENGTH]();

        int nReceiveLength = RECEIVED_BUFFER_LENGTH;

        nReceiveLength = Receive(szReceiveArray, nReceiveLength, TIMEOUT);

        if (nReceiveLength <= )

        {

            Log("Recveived Time-Out(%d)...", nReceiveLength);

            delete[] szReceiveArray;

            break;

        }

        Log("Received (%d) Bytes", nReceiveLength);  

        char *szReceive = szReceiveArray;

        do

        {

            if(nPackageDataLength == )

            {

                if(szReceive[] != HEADER)

                {

                    Log("Package Data Header-Analysis Error, Size(%d).", nReceiveLength);

                    break;

                }

                if(nReceiveLength < PACKHEADERLENGTH)

                {

                    Log("Package Data Length-Analysis Error, Size(%d).", nReceiveLength);

                    break;

                }

                //offset HEADER length

                char *szPackageDataLength = szReceive + sizeof(char);

                //包数据的长度(不包含包头长度)

                LengthResolve(szPackageDataLength, nPackageDataLength); 

                szPackageCleaner = new char[nPackageDataLength + PACKHEADERLENGTH + ]();

                szPackageIterator = szPackageCleaner;

                memcpy(szPackageIterator, szReceive, PACKHEADERLENGTH);

                szPackageIterator += PACKHEADERLENGTH;

                szReceive += PACKHEADERLENGTH;

                nReceiveLength -= PACKHEADERLENGTH;

            }

            //已接收的包数据长度 < 包数据长度 = 一个不完整的包

            if(nReceiveLength < nPackageDataLength)

            {

                memcpy(szPackageIterator, szReceive, nReceiveLength);

                szPackageIterator += nReceiveLength;

                nPackageDataLength -= nReceiveLength;

                szReceive += nReceiveLength;

                nReceiveLength -= nReceiveLength;

            }

            else//(nReceiveLength >= nPackageDataLength)

            {

                //已接收的包数据长度 == 包数据长度 = 一个完整的包

                //已接收的包数据长度 > 包数据长度  = 至少有一个完整的包 + 至少一个数据片段

                memcpy(szPackageIterator, szReceive, nPackageDataLength);

                //szPackageIterator += nPackageDataLength;

                Resolve(szPackageCleaner, (szPackageIterator - szPackageCleaner) + nPackageDataLength);

                szReceive += nPackageDataLength;

                nReceiveLength -= nPackageDataLength;

                nPackageDataLength = ;

                delete[] szPackageCleaner;

                szPackageCleaner = NULL;

            }            

        }while(nReceiveLength > );    

        delete[] szReceiveArray;

        Sleep();

    }while(IsStop);//Receiving

    if(szPackageCleaner != NULL)

        delete[] szPackageCleaner;

    return ;

}

三、说明

网络数据包接收，最好是有超时机制的，比如2秒左右。

if(nReceiveLength < PACKHEADERLENGTH)

{

         Log("Package Data Length-Analysis Error, Size(%d).", nReceiveLength);

         //这里会出现些问题

         break;

}

问题描述：
　　假如一个完整的数据包解析后，剩余的接收长度 < PACKHEADERLENGTH, 即包头HEADER校验正确，但是解析包数据长度的时接收到的数据不足以解析出

数据要接收的长度。此策略会丢弃包数据至下一个正确的包被正确解析，这个和缓冲区设置的长度是没有直接关系的，当然长度要大于PACKHEADERLENGTH.

要解决这个问题，可以在 break; 之前保存这个数据片，并在和下次接收的拼接解析数据长度。

此策略不是最好的更不是最优的，更好的可能就在你那里呢，有你的指点我相信会更好的。

巴特西

一个C++版的网络数据包解析策略

C++版的网络数据包解析策略(升级版)

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