accept() - accept a connection on a socket
#include <sys/types.h>
#include <sys/socket.h>
int accept (int s, struct sockaddr *addr, int *addrlen)
The argument s is a socket that has been created with socket(2), bound to an address with bind(2), and is listening for connections after a listen(2). The accept(2) argument extracts the first connection request on the queue of pending connections, creates a new socket with the same properties of s and allocates a new file descriptor for the socket. If no pending connections are present on the queue and the socket is not marked as non-blocking, accept(2) blocks the caller until a connection is present. If the socket is marked non-blocking and no pending connections are present on the queue, accept(2) returns an error as described below. The accepted socket may not be used to accept more connections. The original socket s remains open.
If addr and addrlen are both non-NULL, accept(2) fills the argument addr with the address of the connecting entity, as known to the communications layer. The exact format of the addr parameter is determined by the domain in which the communication is occurring. The addrlen is a value-result parameter; it should initially contain the amount of space pointed to by addr; on return it will contain the actual length (in bytes) of the address returned. This call is used with connection-based socket types, such as SOCK_STREAM.
If either argument is null, no information is returned.
You can select(2) a socket for the purposes of doing an accept(2) by selecting it for read.
The call returns -1 on error. If it succeeds, it returns a non-negative integer that is a descriptor for the accepted socket.
The accept(2) will fail if:
bind(2)
connect(2)
listen(2)
select(2)
socket(2)