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 protocol,
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 connections
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 immediately estab‐
lished; the connection will be established asyn‐
chronously.
EINTR The attempt to establish a connection was interrupted
by delivery of a signal that was caught; the connec‐
tion 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 connection
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 (probably
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 family 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 destination 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 connected.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
├─────────────────────────────┼─────────────────────────────┤
│Standard │See standards(5). │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOclose(2), poll(2), accept(3XNET), bind(3XNET), getsockname(3XNET),
select(3C), send(3XNET), shutdown(3XNET), socket(3XNET), attributes(5),
standards(5)SunOS 5.11 10 Jun 2002 connect(3XNET)
