12.5 Winsock如何支持读超时
12.5 Winsock如何支持读超时
[url]http://www.opencjk.org/~scz/network/200610101459.txt[/url]
A: scz@nsfocus
Winsock有个独有SO_RCVTIMEO选项:
--------------------------------------------------------------------------
int i = timeout;
if
(
SOCKET_ERROR == setsockopt
(
s,
SOL_SOCKET,
SO_RCVTIMEO,
( char * )&i,
sizeof( i )
)
)
{
... ...
}
--------------------------------------------------------------------------
如果碰上不支持SO_RCVTIMEO选项的情形，还可以利用select()实现读超时:
--------------------------------------------------------------------------
static int recv_with_timeout
(
SOCKET s,
char FAR *buf,
int len,
int flags,
unsigned int timeout
)
{
int error;
fd_set rset,
eset;
struct timeval tv;
int ret = SOCKET_ERROR;
FD_ZERO( &rset );
FD_ZERO( &eset );
FD_SET( s, &rset );
FD_SET( s, &eset );
tv.tv_sec = timeout;
tv.tv_usec = 0;
error = select( 0, &rset, NULL, &eset, timeout ? &tv : NULL );
if ( SOCKET_ERROR == error )
{
}
else if ( 0 == error )
{
}
else if ( FD_ISSET( s, &rset ) )
{
ret = recv( s, buf, len, flags );
}
else
{
}
return( ret );
} /* end of recv_with_timeout */
--------------------------------------------------------------------------
Q: 系统支持SO_RCVTIMEO选项，但实测下来读超时没有生效。
A: scz@nsfocus 2006-10-10 14:44
检查一下如何创建套接字的，要确保在重叠套接字上使用SO_RCVTIMEO选项:
--------------------------------------------------------------------------
SOCKET s;
#if 1
s = socket( PF_INET, SOCK_STREAM, IPPROTO_TCP );
#else
s = WSASocket
(
PF_INET,
SOCK_STREAM,
IPPROTO_TCP,
NULL,
0,
WSA_FLAG_OVERLAPPED
);
#endif
if ( INVALID_SOCKET == s )
{
... ...
}
--------------------------------------------------------------------------
非重叠套接字(non-overlapped socket)上SO_RCVTIMEO选项无效。
