connect()

Initiate a connection on a socket

Synopsis:

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

int connect( int s,
             const struct sockaddr * name,
             socklen_t namelen );

Arguments:

s

The descriptor of the socket on which to initiate the connection.

name

The name of the socket to connect to for a SOCK_STREAM connection.

namelen

The length of the name, in bytes.

Library:

libsocket

Use the -l socket option to qcc to link against this library.

Description:

The connect() function establishes the connection according to the socket type specified by s:

SOCK_DGRAM

Specifies the peer that the socket is to be associated with. This address is the one that datagrams are to be sent to, and the only one that datagrams are to be received from.

SOCK_STREAM

This call attempts to make a connection to another socket. The other socket is specified by name, which is an address in the communications space of that socket. Each communications space interprets name in its own way.

Stream sockets may successfully connect only once, whereas datagram sockets may use connect() multiple times to change their association. Datagram sockets may dissolve the association by connecting to an invalid address, such as a null address.

Returns:

0

Success.

-1

An error occurred (errno is set).

Errors:

EADDRINUSE

The address is already in use.

EADDRNOTAVAIL

The specified address isn't available on this machine.

EAFNOSUPPORT

Addresses in the specified address family cannot be used with this socket.

EALREADY

The socket is nonblocking; a previous connection attempt hasn't yet been completed.

EBADF

Invalid descriptor s.

ECONNABORTED

The connect() was terminated under software control.

ECONNREFUSED

The attempt to connect was forcefully rejected.

EFAULT

The name parameter specifies an area outside the process address space.

EHOSTUNREACH

No route to host; the host system can't be reached.

EINPROGRESS

The socket is nonblocking; the connection can't be completed immediately. It's possible to do a select() for completion by selecting the socket for writing.

EISCONN

The socket is already connected.

ENETUNREACH

The network isn't reachable from this host.

ETIMEDOUT

The attempt to establish a connection timed out; no connection was made.

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Protocols such as TCP do not allow further connection requests on a socket after an ECONNREFUSED error. In such a situation, the socket must be closed and a new one created before a subsequent attempt for connection is made.

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Classification:

POSIX 1003.1

See also:

ICMP, IP, TCP, and UDP protocols

accept(), bind(), getsockname(), nbaconnect(), select(), socket()