NAME

accept −  Accepts a new connection on a socket

SYNOPSIS

#include <sys/types.h>
#include <sys/socket.h>

int accept (

int socket,
struct sockaddr ∗address,
int ∗address_len );

PARAMETERS

socket Specifies a socket that was created with the socket() function, has been bound to an address with the bind() function, and has issued a successful call to the listen() function. 

address
Points to a sockaddr structure, the format of which is determined by the domain and by the behavior requested for the socket.  The sockaddr structure is an overlay for a sockaddr_in, sockaddr_un, or sockaddr_ns structure, depending on which of the supported address families is active.  If the compile-time option _SOCKADDR_LEN is defined before the sys/socket.h header file is included, the sockaddr structure takes 4.4BSD behavior, with a field for specifying the length of the socket address.  Otherwise, the default 4.3BSD sockaddr structure is used, with the length of the socket address assumed to be 14 bytes or less.  You can specify NULL to indicate that the address of the peer is not required.

If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is defined with the name osockaddr. 

address_len
Specifies the length of the sockaddr structure pointed to by the address parameter.  If the address parameter is NULL then this parameter is ignored. 

DESCRIPTION

The accept() function extracts the first connection on the queue of pending connections, creates a new socket with the same properties as the specified socket, and allocates a new file descriptor for that socket. 

If the listen() queue is empty of connection requests, the accept() function blocks a calling socket of the blocking type until a connection is present, or returns an [EWOULDBLOCK] for sockets marked nonblocking. 

The accepted socket cannot itself accept more connections.  The original socket remains open and can accept more connections. 

RETURN VALUES

Upon successful completion, the accept() function returns the nonnegative socket descriptor of the accepted socket.  Additionally, if the address parameter was specified then it places the address of the peer in the sockaddr structure pointed to by the address parameter, and sets the address_len parameter to the length of address. If the accept() function fails, a value of -1 is returned and errno is set to indicate the error. 

ERRORS

If the accept() function fails, errno may be set to one of the following values:

[EINVAL] The socket is not accepting connections. 

[EBADF] The socket parameter is not valid. 

[ENOMEM] The system was unable to allocate kernel memory to increase the process descriptor table. 

[ENOTSOCK]
The socket parameter refers to a file, not a socket. 

[EOPNOTSUPP]
The referenced socket can not accept connections.

[EFAULT] The address parameter is not in a writable part of the user address space. 

[EWOULDBLOCK]
The socket is marked nonblocking, and no connections are present to be accepted.

[EMFILE] There are too many open file descriptors. 

RELATED INFORMATION

Functions: bind(2), connect(2), listen(2), socket(2)