recvfrom设置超时

struct timeval tv;int ret;tv.tv_sec = 10;tv.tv_usec = 0;if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {printf("socket option  SO_RCVTIMEO not support\n");return;}if ((ret = recvfrom(s, buf, sizeof buf, 0, NULL, NULL)) < 0) {if (ret == EWOULDBLOCK || ret == EAGAIN)printf("recvfrom timeout\n");elseprintf("recvfrom err:%d\n", ret);}