1.\" $NetBSD: connect.2,v 1.17 2000/06/17 19:33:34 hubertf Exp $ 2.\" 3.\" Copyright (c) 1983, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)connect.2 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt CONNECT 2 38.Os 39.Sh NAME 40.Nm connect 41.Nd initiate a connection on a socket 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include <sys/types.h> 46.Fd #include <sys/socket.h> 47.Ft int 48.Fn connect "int s" "const struct sockaddr *name" "socklen_t namelen" 49.Sh DESCRIPTION 50The parameter 51.Fa s 52is a socket. 53If it is of type 54.Dv SOCK_DGRAM , 55this call specifies the peer with which the socket is to be associated; 56this address is that to which datagrams are to be sent, 57and the only address from which datagrams are to be received. 58If the socket is of type 59.Dv SOCK_STREAM , 60this call attempts to make a connection to 61another socket. 62The other socket is specified by 63.Fa name , 64which is an address in the communications space of the socket. 65Each communications space interprets the 66.Fa name 67parameter in its own way. 68Generally, stream sockets may successfully 69.Fn connect 70only once; datagram sockets may use 71.Fn connect 72multiple times to change their association. 73Datagram sockets may dissolve the association 74by connecting to an invalid address, such as a null address. 75.Sh RETURN VALUES 76If the connection or binding succeeds, 0 is returned. 77Otherwise a -1 is returned, and a more specific error 78code is stored in 79.Va errno . 80.Sh ERRORS 81The 82.Fn connect 83call fails if: 84.Bl -tag -width Er 85.It Bq Er EBADF 86.Fa s 87is not a valid descriptor. 88.It Bq Er ENOTSOCK 89.Fa s 90is a descriptor for a file, not a socket. 91.It Bq Er EADDRNOTAVAIL 92The specified address is not available on this machine. 93.It Bq Er EAFNOSUPPORT 94Addresses in the specified address family cannot be used with this socket. 95.It Bq Er EISCONN 96The socket is already connected. 97.It Bq Er ETIMEDOUT 98Connection establishment timed out without establishing a connection. 99.It Bq Er ECONNREFUSED 100The attempt to connect was forcefully rejected. 101.It Bq Er ENETUNREACH 102The network isn't reachable from this host. 103.It Bq Er EADDRINUSE 104The address is already in use. 105.It Bq Er EFAULT 106The 107.Fa name 108parameter specifies an area outside 109the process address space. 110.It Bq Er EINPROGRESS 111The socket is non-blocking and the connection cannot be completed immediately. 112It is possible to 113.Xr select 2 114or 115.Xr poll 2 116for completion by selecting or polling the socket for writing. 117The success or failure of the connect operation may be determined by using 118.Xr getsockopt 2 119to read the socket error status with the 120.Dv SO_ERROR 121option at the 122.Dv SOL_SOCKET 123level. 124The returned socket error status is zero on success, or one of the 125error codes listed here on failure. 126.It Bq Er EALREADY 127The socket is non-blocking 128and a previous connection attempt 129has not yet been completed. 130.El 131.Pp 132The following errors are specific to connecting names in the 133.Ux 134domain. 135These errors may not apply in future versions of the 136.Ux 137IPC domain. 138.Bl -tag -width Er 139.It Bq Er ENOTDIR 140A component of the path prefix is not a directory. 141.It Bq Er ENAMETOOLONG 142A component of a pathname exceeded 143.Dv {NAME_MAX} 144characters, or an entire path name exceeded 145.Dv {PATH_MAX} 146characters. 147.It Bq Er ENOENT 148The named socket does not exist. 149.It Bq Er EACCES 150Search permission is denied for a component of the path prefix, or 151write access to the named socket is denied. 152.It Bq Er ELOOP 153Too many symbolic links were encountered in translating the pathname. 154.El 155.Sh SEE ALSO 156.Xr accept 2 , 157.Xr poll 2 , 158.Xr select 2 , 159.Xr socket 2 , 160.Xr getsockname 2 , 161.Xr getsockopt 2 162.Sh HISTORY 163The 164.Fn connect 165function call appeared in 166.Bx 4.2 . 167