Question

Let s be a file descriptor of a socket made by socket(PF_INET, ...).

If I call accept(s, (struct sockaddr *) &addr, ...), where addr is of type struct sockaddr_in, can I assume that the format of the returned address is IPv4, i.e.,

addr.sin_family == AF_INET ?

Answer 1

From The Open Group’s description:

The accept() function shall extract the first connection on the queue
of pending connections, create a new socket with the same socket
type protocol and address family as the specified socket, and
allocate a new file descriptor for that socket.