socket通讯可靠性

/*-------------------------------------------------------------------

    SOCKETROUTE.C——阻塞模式下使用的常用子程序

                     (c)by 浅墨浓香,2015.6.25

---------------------------------------------------------------------*/

#include <windows.h>

#include "Message.h"

#include "SocketRoute.h"



#pragma comment(lib,"Ws2_32.lib")



//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

// 在规定的时间内等待数据到达

// 输入：dwTime = 需要等待的时间（微秒）

// 返回值：0            ——超时而返回

//         SOCKET_ERROR ——出错而返回

//         X(x>0)       ——就绪的套接字数量

//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

int WaitData(SOCKET sock, DWORD dwTime)

{

    FD_SET  fds;

    TIMEVAL  tv;



    fds.fd_count = 1;

    fds.fd_array[0] = sock;

    

    tv.tv_sec = 0;

    tv.tv_usec = dwTime;



    return select(0, &fds, NULL, NULL, &tv);

}



//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

// 接收规定字节的数据，如果缓冲区中的数据不够则等待

// 返回：FALSE，连接中断或发生错误

//       TRUE，成功

//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

BOOL RecvData(SOCKET sock, char* pBuffer, int nBytes)

{

    int nStartTime;

    int nRet,nRecv;



    nStartTime = GetTickCount();

    nRecv = 0;



    while ((GetTickCount()-nStartTime)<10*1000)  //查看是否超时

    {

        nRet = WaitData(sock, 100 * 1000);  //等待数据100ms

        if (SOCKET_ERROR == nRet)  //连接错误

            return FALSE;



        if (0 == nRet) //超时

            break;



        do 

        {

            //接收数据，直至收完指定的字节数

            nRecv += recv(sock, pBuffer + nRecv, nBytes - nRecv, 0);



            if (nRecv == SOCKET_ERROR || nRecv == 0)

                return FALSE;



            if (nRecv == nBytes)

                return TRUE;



        } while (nRecv < nBytes);        

    }

    return TRUE;

}



//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

// 接收一个符合规范的数据包 

// 参数： pBuffer用来接收数据的缓冲区

//        nBytes 数据区最大的空间

// 返回： FALSE——失败

//        TRUE ——成功

//注意：这里的nBytes不要指要接收的字节数，只是用来判断缓冲区是否只够大

//>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>



BOOL RecvPacket(SOCKET sock, char* pBuffer, int nBytes)

{

    MSGSTRUCT* pMsgStruct;

    int iRet;



    pMsgStruct = (MSGSTRUCT*)pBuffer;



    //接收数据包头部并检测数据是否正常

    iRet = RecvData(sock, pBuffer, sizeof(MSGHEAD));



    if (iRet)  //如果成功接收数据

    {

        if (pMsgStruct->MsgHead.cbSize <= sizeof(MSGHEAD) ||

            pMsgStruct->MsgHead.cbSize > nBytes)

            return FALSE;



        //接收余下的数据

        iRet = RecvData(sock, pBuffer + sizeof(MSGHEAD), pMsgStruct->MsgHead.cbSize - sizeof(MSGHEAD));

    }

    return iRet;

}