connect(3SOCKET) (man pages section 3: Networking Library Functions)

man pages section 3: Networking Library Functions

connect(3SOCKET)

NAME

connect– initiate a connection on a socket

SYNOPSIS

cc [ flag ... ] file ... -lsocket -lnsl [ library ... ]
#include <sys/types.h>
#include <sys/socket.h>

s

name

namelen

DESCRIPTION

The parameter s is a socket. If it is of type SOCK_DGRAM, connect() specifies the peer with which the socket is to be associated; this address is the address to which datagrams are to be sent if a receiver is not explicitly designated; it is the only address from which datagrams are to be received. If the socket s is of type SOCK_STREAM, connect() attempts to make a connection to another socket. The other socket is specified by name. name is an address in the communication space of the socket. Each communication space interprets the name parameter in its own way. If s is not bound, then it will be bound to an address selected by the underlying transport provider. Generally, stream sockets may successfully connect() only once; datagram sockets may use connect() multiple times to change their association. Datagram sockets may dissolve the association by connecting to a null address.

RETURN VALUES

If the connection or binding succeeds, 0 is returned. Otherwise, -1 is returned and sets errno to indicate the error.

ERRORS

The call fails if:

EACCES: Search permission is denied for a component of the path prefix of the pathname in name.
EADDRINUSE: The address is already in use.
EADDRNOTAVAIL: The specified address is not available on the remote machine.
EAFNOSUPPORT: Addresses in the specified address family cannot be used with this socket.
EALREADY: The socket is non-blocking and a previous connection attempt has not yet been completed.
EBADF: s is not a valid descriptor.
ECONNREFUSED: The attempt to connect was forcefully rejected. The calling program should close(2) the socket descriptor, and issue another socket(3SOCKET) call to obtain a new descriptor before attempting another connect() call.
EINPROGRESS: The socket is non-blocking and the connection cannot be completed immediately. It is possible to select(3C) for completion by selecting the socket for writing. However, this is only possible if the socket STREAMS module is the topmost module on the protocol stack with a write service procedure. This will be the normal case.
EINTR: The connection attempt was interrupted before any data arrived by the delivery of a signal.
EINVAL: namelen is not the size of a valid address for the specified address family.
EIO: An I/O error occurred while reading from or writing to the file system.
EISCONN: The socket is already connected.
ELOOP: Too many symbolic links were encountered in translating the pathname in name.
ENETUNREACH: The network is not reachable from this host.
ENOENT: A component of the path prefix of the pathname in name does not exist.
ENOENT: The socket referred to by the pathname in name does not exist.
ENOSR: There were insufficient STREAMS resources available to complete the operation.
ENXIO: The server exited before the connection was complete.
ETIMEDOUT: Connection establishment timed out without establishing a connection.
EWOULDBLOCK: The socket is marked as non-blocking, and the requested operation would block.

The following errors are specific to connecting names in the UNIX domain. These errors may not apply in future versions of the UNIX IPC domain.

ENOTDIR: A component of the path prefix of the pathname in name is not a directory.
ENOTSOCK: s is not a socket.
ENOTSOCK: name is not a socket.
EPROTOTYPE: The file referred to by name is a socket of a type other than type s (for example, s is a SOCK_DGRAM socket, while name refers to a SOCK_STREAM socket).

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
MT-Level	Safe