connect(3XNET) X/Open Networking Services Library Functions connect(3XNET)NAMEconnect - connect a socket
SYNOPSIS
cc [ flag ... ] file ... -lxnet [ library ... ]
#include <sys/socket.h>
int connect(int socket, const struct sockaddr *address, socklen_t
address_len);
DESCRIPTION
The connect() function requests a connection to be made on a socket.
The function takes the following arguments:
socket Specifies the file descriptor associated with the
socket.
address Points to a sockaddr structure containing the peer
address. The length and format of the address depend
on the address family of the socket.
address_len Specifies the length of the sockaddr structure pointed
to by the address argument.
If the socket has not already been bound to a local address, connect()
will bind it to an address which, unless the socket's address family
is AF_UNIX, is an unused local address.
If the initiating socket is not connection-mode, then connect() sets
the socket's peer address, but no connection is made. For SOCK_DGRAM
sockets, the peer address identifies where all datagrams are sent on
subsequent send(3XNET) calls, and limits the remote sender for subse‐
quent recv(3XNET) calls. If address is a null address for the proto‐
col, the socket's peer address will be reset.
If the initiating socket is connection-mode, then connect() attempts to
establish a connection to the address specified by the address argu‐
ment.
If the connection cannot be established immediately and O_NONBLOCK is
not set for the file descriptor for the socket, connect() will block
for up to an unspecified timeout interval until the connection is
established. If the timeout interval expires before the connection is
established, connect() will fail and the connection attempt will be
aborted. If connect() is interrupted by a signal that is caught while
blocked waiting to establish a connection, connect() will fail and set
errno to EINTR, but the connection request will not be aborted, and the
connection will be established asynchronously.
If the connection cannot be established immediately and O_NONBLOCK is
set for the file descriptor for the socket, connect() will fail and set
errno to EINPROGRESS, but the connection request will not be aborted,
and the connection will be established asynchronously. Subsequent calls
to connect() for the same socket, before the connection is established,
will fail and set errno to EALREADY.
When the connection has been established asynchronously, select(3C) and
poll(2) will indicate that the file descriptor for the socket is ready
for writing.
The socket in use may require the process to have appropriate privi‐
leges to use the connect() function.
USAGE
If connect() fails, the state of the socket is unspecified. Portable
applications should close the file descriptor and create a new socket
before attempting to reconnect.
RETURN VALUES
Upon successful completion, connect() returns 0. Otherwise, −1 is
returned and errno is set to indicate the error.
ERRORS
The connect() function will fail if:
EADDRNOTAVAIL The specified address is not available from the
local machine.
EAFNOSUPPORT The specified address is not a valid address
for the address family of the specified socket.
EALREADY A connection request is already in progress for
the specified socket.
EBADF The socket argument is not a valid file
descriptor.
ECONNREFUSED The target address was not listening for con‐
nections or refused the connection request.
EFAULT The address parameter can not be accessed.
EINPROGRESS O_NONBLOCK is set for the file descriptor for
the socket and the connection cannot be immedi‐
ately established; the connection will be
established asynchronously.
EINTR The attempt to establish a connection was
interrupted by delivery of a signal that was
caught; the connection will be established
asynchronously.
EISCONN The specified socket is connection-mode and is
already connected.
ENETUNREACH No route to the network is present.
ENOTSOCK The socket argument does not refer to a socket.
EPROTOTYPE The specified address has a different type than
the socket bound to the specified peer address.
ETIMEDOUT The attempt to connect timed out before a con‐
nection was made.
If the address family of the socket is AF_UNIX, then connect() will
fail if:
EIO An I/O error occurred while reading from or
writing to the file system.
ELOOP Too many symbolic links were encountered in
translating the pathname in address.
ENAMETOOLONG A component of a pathname exceeded NAME_MAX
characters, or an entire pathname exceeded
PATH_MAX characters.
ENOENT A component of the pathname does not name an
existing file or the pathname is an empty
string.
ENOTDIR A component of the path prefix of the pathname
in address is not a directory.
The connect() function may fail if:
EACCES Search permission is denied for a component of
the path prefix; or write access to the named
socket is denied.
EADDRINUSE Attempt to establish a connection that uses
addresses that are already in use.
ECONNRESET Remote host reset the connection request.
EHOSTUNREACH The destination host cannot be reached (proba‐
bly because the host is down or a remote router
cannot reach it).
EINVAL The address_len argument is not a valid length
for the address family; or invalid address fam‐
ily in sockaddr structure.
ENAMETOOLONG Pathname resolution of a symbolic link produced
an intermediate result whose length exceeds
PATH_MAX.
ENETDOWN The local interface used to reach the destina‐
tion is down.
ENOBUFS No buffer space is available.
ENOSR There were insufficient STREAMS resources
available to complete the operation.
EOPNOTSUPP The socket is listening and can not be con‐
nected.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOclose(2), poll(2), accept(3XNET), bind(3XNET), getsockname(3XNET),
select(3C), send(3XNET), shutdown(3XNET), socket(3XNET), attributes(5),
standards(5)SunOS 5.10 10 Jun 2002 connect(3XNET)
