（转）How to recv from socket with timeout

You can use the setsockopt function to set a timeout on receive operations:

SO_RCVTIMEO

Sets the timeout value that specifies the maximum amount of time an input function waits until it completes. It accepts a timeval structure with the number of seconds and microseconds specifying the limit on how long to wait for an input operation to complete. If a receive operation has blocked for this much time without receiving additional data, it shall return with a partial count or errno set to [EAGAIN] or [EWOULDBLOCK] if no data is received. The default for this option is zero, which indicates that a receive operation shall not time out. This option takes a timeval structure. Note that not all implementations allow this option to be set.

struct timeval tv;

tv.tv_sec = 30; /* 30 Secs Timeout */
tv.tv_usec = 0; // Not init'ing this can cause strange errors


setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,sizeof(struct timeval));