int setsockopt(int s, int level, int optname, void *optval, int optlen);level = SOL_SOCKEToptname = SO_SNDTIMEO optval = struct timeval 发送超时值或者接收超时值
int setsockopt(int s, int level, int optname, void *optval, int optlen);
level = SOL_SOCKET
optname = SO_SNDTIMEO
optval = struct timeval 发送超时值或者接收超时值