connect()

initiate a connection on a socket

Synopsis:

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

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

Description:

This function establishes the connection according to the socket type specified by s:

SOCK_DGRAM

This call 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 do a 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:

If an error occurred, errno could contain one of the following:

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

s isn't a valid descriptor.

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.

Classification:

POSIX 1003.1g (draft)

See also:

ICMP, IP, TCP, and UDP protocols, accept(), bind(), getsockname(), socket()

select() in the C Library Reference