connect(2)							System Calls Manual							connect(2)

NAME

       connect - Connects two sockets

SYNOPSIS

       #include <sys/socket.h>

       int connect (	  int socket,	   const struct sockaddr *address,	socklen_t address_len );

       [XNS4.0]  The  definition  of  the  connect()  function	in XNS4.0 uses a size_t data type instead of a socklen_t data type as specified in
       XNS5.0 (the previous definition).

       [Tru64 UNIX]  The following definition of the connect() function  does not conform to current standards and is supported only for  backward
       compatibility (see standards(5)):

       int connect (	  int socket,	   struct sockaddr *address,	  int address_len );

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       connect():  XNS5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies  a  file  descriptor  for the socket.	Points to a sockaddr structure, the format of which is determined by the domain and by the
       behavior requested for the socket.  The sockaddr structure is an overlay for a sockaddr_in or sockaddr_un structure, depending on which	of
       the supported address families is active.

	      [Tru64  UNIX]    If  the	compile-time option _SOCKADDR_LEN is defined before the sys/socket.h header file is included, the sockaddr
	      structure takes 4.4BSD behavior, with a field for specifying the length of the socket address.  Otherwise, the default 4.3BSD  sock-
	      addr structure is used, with the length of the socket address assumed to be 14 bytes or less.

	      If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is defined with the name osockaddr.  Specifies the length of the sockaddr
	      structure pointed to by the address parameter.

DESCRIPTION

       The connect() function requests a connection between two sockets.  The kernel sets up the communications links between  the  sockets;  both
       sockets must use the same address format and protocol.

       The  connect()  function  performs  a  different  action for each of the following types of initiating sockets: If the initiating socket is
       SOCK_DGRAM, the connect() function establishes the peer address.  The peer address identifies the socket where all datagrams  are  sent	on
       subsequent  send()  functions.  It also identifies the socket from where datagrams can be received; datagrams from other peer addresses are
       not delivered.  If address is a null address for the protocol, the socket's peer address is reset.

	      No connections are made by this connect function.  If the initiating socket is SOCK_STREAM, the connect() function attempts to  make
	      a  connection  to  the socket specified by the address parameter.  Each communication space interprets the address parameter differ-
	      ently.

       If the function fails for a connection mode socket, applications should use the close() function to deallocate the socket  and  descriptor.
       If attempting to reinitiate the connection, applications should create a new socket.

       If the connection cannot be established immediately, one of the following occurs: If the socket file descriptor is marked non-blocking, the
       connect() function fails and sets errno to [EINPROGRESS]. However, the connection request is not aborted; the  connection  will	be  estab-
       lished  asynchronously.	 If  you make a call to connect() for the same socket before the connection is established, the function fails and
       sets errno to [EALREADY].  If the socket file descriptor is marked blocking, the connect() function blocks for  an  unspecified	amount	of
       time  until  the  connection  is established.  If the timeout interval expires before the connection is established, the function fails and
       aborts the connection attempt.  While blocked, if connect() is interrupted by a signal, it fails and sets errno to [EINTR].   However,  the
       connection request is not aborted; the connection is established asynchronously.

RETURN VALUES

       Upon  successful  completion, the connect() function returns a value of 0 (zero).  Otherwise, a value of -1 is returned and errno is set to
       indicate the error.

ERRORS

       If the connect() function fails, errno may be set to one of the following values: Search permission is denied for a component of  the  path
       prefix; or write access to the named socket is denied.

	      [XNS4.0]	This error applies to AF_UNIX sockets only.  The specified address is already in use.  The specified address is not avail-
	      able from the local machine.  The addresses in the specified address family cannot be used with this socket.  A  connection  request
	      is  already  in  progress  for  the specified socket.  The socket parameter is not valid.  The attempt to connect was rejected.  The
	      remote host reset the connection request.  The address parameter is not in a readable part of the user address space.  The specified
	      host  is	not  reachable.   O_NONBLOCK is set for the file descriptor for the socket and the connection cannot be immediately estab-
	      lished; the connection will be established asynchronously.  The connect() function was interrupted by a signal while waiting for the
	      connection  to be established.  The connection establishment may continue asynchronously.  The value of the address_len parameter is
	      invalid for the specified address family; or the sa_family field in the socket address structure is invalid for the  protocol.   For
	      an AF_UNIX socket, an I/O error occurred while reading from or writing to the file system.  The socket is already connected.  For an
	      AF_UNIX socket, too many symbolic links were encountered in translating the pathname  in	address.   A  component  of  the  pathname
	      exceeded	NAME_MAX characters, or an entire pathname exceeded PATH_MAX characters.  The local network connection is not operational.
	      No route to the network or host is present.  Insufficient resources are available in the	system	to  complete  the  call.   For	an
	      AF_UNIX  socket,	a  component  of  the  pathname  does not name an existing file or the pathname is an empty string.  The available
	      STREAMS resources were insufficient for the operation to complete.  For an AF_UNIX socket, a component of the  path  prefix  of  the
	      pathname in address is not a directory.  The socket parameter refers to a file, not a socket.  The socket is listening and cannot be
	      connected.  The specified address has a different type than the socket bound to the specified peer address.  The establishment of  a
	      connection  timed  out  before  a  connection was made.  [Tru64 UNIX]  The socket is marked nonblocking, so the connection cannot be
	      immediately completed.  The application program can select the socket for writing during the connection process.

RELATED INFORMATION

       Functions: accept(2), bind(2), socket(2), getsockname(2), select(2), send(2).

       Standards: standards(5).  delim off

																	connect(2)