s A socket descriptor created with the socket() function. msg A pointer to a msghdr structure for receiving the data. flags A bit mask that can contain one or more of the following flags. The mask is built by using a logical OR operation on the appropriate values. Flag Description MSG_OOB Allows you to receive out-of-band data. If out-of-band data is available, it is read first. If no out-of-band data is available, the MSG_OOB flag is ignored. Use send(), sendmsg(), and sendto() functions to send out-of-band data. MSG_PEEK Allows you to peek at the data that is next in line to be received without actually removing it from the system's buffers.