WINDOWS下默认的SOCKET发送和接收缓冲区大小均是4K，你可以用如下代码读出此大小，并修改发送和接收缓冲区。
int rcvbuf;
int rcvbufsize=sizeof(int);
if(getsockopt(m_Socket,SOL_SOCKET,SO_MAX_MSG_SIZE,(char*)&rcvbuf,&rcvbufsize)!
=SOCKET_ERROR)
{
if(rcvbuf<65536)
rcvbuf=65536;
setsockopt(m_Socket,SOL_SOCKET,SO_RCVBUF,(char*)&rcvbuf,rcvbufsize);
}
if(getsockopt(m_Socket,SOL_SOCKET,SO_SNDBUF,(char*)&rcvbuf,&rcvbufsize)!
=SOCKET_ERROR)
{
if(rcvbuf<65536)
rcvbuf=65536;
setsockopt(m_Socket,SOL_SOCKET,SO_SNDBUF,(char*)&rcvbuf,rcvbufsize);
}
