Originální popis anglicky:
connect - connect a socket
Návod, kniha: POSIX Programmer's Manual
#include <sys/socket.h>
int connect(int
socket, const struct sockaddr
* address,
socklen_t
address_len );
The
connect() function shall attempt to make a connection 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()
shall 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() shall set
the socket's peer address, and no connection is made. For SOCK_DGRAM sockets,
the peer address identifies where all datagrams are sent on subsequent
send() functions, and limits the remote sender for subsequent
recv() functions. If
address is a null address for the protocol,
the socket's peer address shall be reset.
If the initiating socket is connection-mode, then
connect() shall attempt
to establish a connection to the address specified by the
address
argument. If the connection cannot be established immediately and O_NONBLOCK
is not set for the file descriptor for the socket,
connect() shall
block for up to an unspecified timeout interval until the connection is
established. If the timeout interval expires before the connection is
established,
connect() shall fail and the connection attempt shall be
aborted. If
connect() is interrupted by a signal that is caught while
blocked waiting to establish a connection,
connect() shall fail and set
errno to [EINTR], but the connection request shall not be aborted, and
the connection shall be established asynchronously.
If the connection cannot be established immediately and O_NONBLOCK is set for
the file descriptor for the socket,
connect() shall fail and set
errno to [EINPROGRESS], but the connection request shall not be
aborted, and the connection shall be established asynchronously. Subsequent
calls to
connect() for the same socket, before the connection is
established, shall fail and set
errno to [EALREADY].
When the connection has been established asynchronously,
select() and
poll() shall indicate that the file descriptor for the socket is ready
for writing.
The socket in use may require the process to have appropriate privileges to use
the
connect() function.
Upon successful completion,
connect() shall return 0; otherwise, -1 shall
be returned and
errno set to indicate the error.
The
connect() function shall 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.
- EINPROGRESS
- O_NONBLOCK is set for the file descriptor for the socket
and the connection cannot be immediately established; the connection shall
be established asynchronously.
- EINTR
- The attempt to establish a connection was interrupted by
delivery of a signal that was caught; the connection shall 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() shall fail
if:
- EIO
- An I/O error occurred while reading from or writing to the
file system.
- ELOOP
- A loop exists in symbolic links encountered during
resolution of 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 the sockaddr
structure.
- ELOOP
- More than {SYMLOOP_MAX} symbolic links were encountered
during resolution of the pathname in address.
- ENAMETOOLONG
- Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
- ENETDOWN
- The local network interface used to reach the destination
is down.
- ENOBUFS
- No buffer space is available.
- EOPNOTSUPP
- The socket is listening and cannot be connected.
The following sections are informative.
None.
If
connect() fails, the state of the socket is unspecified. Conforming
applications should close the file descriptor and create a new socket before
attempting to reconnect.
None.
None.
accept() ,
bind() ,
close() ,
getsockname() ,
poll() ,
select() ,
send() ,
shutdown() ,
socket() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<sys/socket.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
