Linux 如何接受超时的套接字
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How to accept socket with timeout
提问by Boris
Is there is a timeout crossplatform soulution to accept client using acceptfunction without setting socket to non-blocking?
是否有超时跨平台解决方案来接受客户端使用accept函数而不将套接字设置为非阻塞？
I know that i should use selectfunction to it, but what i'm doing wrong?
我知道我应该select对它使用函数，但是我做错了什么？
SOCKET NativesAcceptClient(SOCKET s, int timeout)
{
int iResult;
struct timeval tv;
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(s, &rfds);
tv.tv_sec = (long)timeout;
tv.tv_usec = 0;
iResult = select(s, &rfds, (fd_set *) 0, (fd_set *) 0, &tv);
if(iResult > 0)
{
return accept(s, NULL, NULL);
}
else
{
//always here, even if i connect from another application
}
return 0;
}
How to fix that? Thanks!
如何解决？谢谢！
回答by ryanbwork
The first parameter of the selectcall should be equal to the the highest number file descriptor in your fd_set set plus 1 (see here). Try changing the first argument to s+1; you will need to add some logic when your have more than one socket in your set.
select调用的第一个参数应该等于 fd_set 集合中最大编号的文件描述符加 1（参见此处）。尝试将第一个参数更改为s+1; 当您的集合中有多个套接字时，您将需要添加一些逻辑。
回答by arayq2
The first argument of select() is an int that is at least 1 greaterthan the highest value of the file descriptors in any of the bitsets. In this case
的选择的第一个参数（）是一个int是至少1更大的比文件描述符中的任何位集的最高值。在这种情况下
iResult = select(s + 1, &rfds, (fd_set *) 0, (fd_set *) 0, &tv);
should work.
应该管用。
回答by Remy Lebeau
select()returns >0 if a socket is signaled, 0 on timeout, and -1 on error. What value is select()actually returning to you? You are only checking for >0 and <=0, which means you are not differentiating between -1 and 0. If it is returning 0 then no client is connecting to your socket, but if it is returning -1 then your socket is likely not valid to begin with.
select()如果套接字有信号，则返回 >0，超时时返回 0，错误时返回 -1。什么价值select()实际上回报给你？您只检查 >0 和 <=0，这意味着您没有区分 -1 和 0。如果它返回 0，则没有客户端连接到您的套接字，但如果它返回 -1，则您的套接字很可能开始无效。
