心跳包

文中提到：

//设置KeepAlive
BOOL   bKeepAlive   =   TRUE;
nRet   =   ::setsockopt(m_sockDesc,   SOL_SOCKET,   SO_KEEPALIVE,   (char*)&bKeepAlive,   sizeof(bKeepAlive));
if   (nRet   !=0)
{
sprintf(m_pszError,   "Winsock   error   :   %s   (Error   Code   %d)\n ",   "Socket   SetOpt   failed ",   WSAGetLastError());
return   FALSE;
}

//设置KeepAlive检测时间和次数
TCP_KEEPALIVE   inKeepAlive   =   {0};   //输入参数
unsigned   long   ulInLen   =   sizeof(TCP_KEEPALIVE);

TCP_KEEPALIVE   outKeepAlive   =   {0};   //输出参数
unsigned   long   ulOutLen   =   sizeof(TCP_KEEPALIVE);

unsigned   long   ulBytesReturn   =   0;

//设置socket的keep   alive为10秒，并且发送次数为3次
inKeepAlive.onoff   =   1;
inKeepAlive.keepaliveinterval   =   10000;   //两次KeepAlive探测间的时间间隔
inKeepAlive.keepalivetime   =   3;   //开始首次KeepAlive探测前的TCP空闭时间

nRet   =   WSAIoctl(m_sockDesc,
SIO_KEEPALIVE_VALS,
(LPVOID)&inKeepAlive,
ulInLen,
(LPVOID)&outKeepAlive,
ulOutLen,
&ulBytesReturn,
NULL,
NULL);
if(SOCKET_ERROR   ==   nRet)
{
sprintf(m_pszError,   "Winsock   error   :   %s   (Error   Code   %d)\n ",   "Nonblocking   socket   call   error ",   WSAGetLastError());
return   FALSE;
}

//设置KeepAlive BOOL   bKeepAlive   =   TRUE; nRet   =   ::setsockopt(m_sockDesc,   SOL_SOCKET,   SO_KEEPALIVE,   (char*)&bKeepAlive,   sizeof(bKeepAlive)); if   (nRet   !=0) { sprintf(m_pszError,   "Winsock   error   :   %s   (Error   Code   %d)\n ",   "Socket   SetOpt   failed ",   WSAGetLastError()); return   FALSE; } //设置KeepAlive检测时间和次数 TCP_KEEPALIVE   inKeepAlive   =   {0};   //输入参数 unsigned   long   ulInLen   =   sizeof(TCP_KEEPALIVE);     TCP_KEEPALIVE   outKeepAlive   =   {0};   //输出参数 unsigned   long   ulOutLen   =   sizeof(TCP_KEEPALIVE);     unsigned   long   ulBytesReturn   =   0; //设置socket的keep   alive为10秒，并且发送次数为3次 inKeepAlive.onoff   =   1;   inKeepAlive.keepaliveinterval   =   10000;   //两次KeepAlive探测间的时间间隔 inKeepAlive.keepalivetime   =   3;   //开始首次KeepAlive探测前的TCP空闭时间 nRet   =   WSAIoctl(m_sockDesc,   SIO_KEEPALIVE_VALS, (LPVOID)&inKeepAlive, ulInLen, (LPVOID)&outKeepAlive, ulOutLen, &ulBytesReturn, NULL, NULL); if(SOCKET_ERROR   ==   nRet) { sprintf(m_pszError,   "Winsock   error   :   %s   (Error   Code   %d)\n ",   "Nonblocking   socket   call   error ",   WSAGetLastError()); return   FALSE; }

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