connect() system call

connect(2)                                                         connect(2)



NAME
  connect - Connects two sockets

SYNOPSIS

  #include <sys/types.h>

  #include <sys/socket.h>

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

PARAMETERS

  socket
      Specifies the unique name of the socket.

  address
      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, sockaddr_un, or sockaddr_ns
      structure, depending on which of the supported address families is
      active.  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 sockaddr 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.

  address_len
      Specifies the length of the sockaddr structure pointed to by the
      address parameter.

DESCRIPTION

  The connect() function requests a connection between two sockets.  The ker-
  nel 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 follow-
  ing types of initiating sockets:

    +  If the initiating socket is SOCK_DGRAM, then the connect() function
       establishes the peer address.  The peer address identifies the socket
       where all datagrams are sent on subsequent send() functions.  No con-
       nections are made by this connect function.

    +  If the initiating socket is SOCK_STREAM, then the connect() function
       attempts to make a connection to the socket specified by the address
       parameter.  Each communication space interprets the address parameter
       differently.




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:

  [EBADF]   The socket parameter is not valid.

  [ENOTSOCK]
            The socket parameter refers to a file, not a socket.

  [EADDRNOTAVAIL]
            The specified address is not available from the local machine.

  [EAFNOSUPPORT]
            The addresses in the specified address family cannot be used with
            this socket.

  [EISCONN] The socket is already connected.

  [ETIMEDOUT]
            The establishment of a connection timed out before a connection
            was made.

  [ECONNREFUSED]
            The attempt to connect was rejected.

  [ENETUNREACH]
            No route to the network or host is present.

  [EADDRINUSE]
            The specified address is already in use.

  [EFAULT]  The address parameter is not in a readable part of the user
            address space.

  [EWOULDBLOCK]
            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.

  [EINTR]   The connect() function was interrupted by a signal while waiting
            for the connection to be established.  The connection establish-
            ment may continue asynchronously.

RELATED INFORMATION

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