1.\" $NetBSD: connect.2,v 1.24 2003/08/07 16:43:56 agc 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. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)connect.2 8.1 (Berkeley) 6/4/93 31.\" 32.Dd October 16, 2001 33.Dt CONNECT 2 34.Os 35.Sh NAME 36.Nm connect 37.Nd initiate a connection on a socket 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/socket.h 42.Ft int 43.Fn connect "int s" "const struct sockaddr *name" "socklen_t namelen" 44.Sh DESCRIPTION 45The parameter 46.Fa s 47is a socket. 48If it is of type 49.Dv SOCK_DGRAM , 50this call specifies the peer with which the socket is to be associated; 51this address is that to which datagrams are to be sent, 52and the only address from which datagrams are to be received. 53If the socket is of type 54.Dv SOCK_STREAM , 55this call attempts to make a connection to 56another socket. 57The other socket is specified by 58.Fa name , 59which is an address in the communications space of the socket. 60.Fa namelen 61indicates the amount of space pointed to by 62.Fa name , 63in bytes. 64Each communications space interprets the 65.Fa name 66parameter in its own way. 67Generally, stream sockets may successfully 68.Fn connect 69only once; datagram sockets may use 70.Fn connect 71multiple times to change their association. 72Datagram sockets may dissolve the association 73by connecting to an invalid address, such as a null address. 74.Sh RETURN VALUES 75If the connection or binding succeeds, 0 is returned. 76Otherwise a -1 is returned, and a more specific error 77code is stored in 78.Va errno . 79.Sh ERRORS 80The 81.Fn connect 82call fails if: 83.Bl -tag -width Er 84.It Bq Er EBADF 85.Fa s 86is not a valid descriptor. 87.It Bq Er ENOTSOCK 88.Fa s 89is a descriptor for a file, not a socket. 90.It Bq Er EADDRNOTAVAIL 91The specified address is not available on this machine. 92.It Bq Er EAFNOSUPPORT 93Addresses in the specified address family cannot be used with this socket. 94.It Bq Er EISCONN 95The socket is already connected. 96.It Bq Er ETIMEDOUT 97Connection establishment timed out without establishing a connection. 98.It Bq Er ECONNREFUSED 99The attempt to connect was forcefully rejected. 100.It Bq Er ENETUNREACH 101The network isn't reachable from this host. 102.It Bq Er EADDRINUSE 103The address is already in use. 104.It Bq Er EFAULT 105The 106.Fa name 107parameter specifies an area outside 108the process address space. 109.It Bq Er EINPROGRESS 110The socket is non-blocking and the connection cannot be completed immediately. 111It is possible to 112.Xr select 2 113or 114.Xr poll 2 115for completion by selecting or polling the socket for writing. 116The success or failure of the connect operation may be determined by using 117.Xr getsockopt 2 118to read the socket error status with the 119.Dv SO_ERROR 120option at the 121.Dv SOL_SOCKET 122level. 123The returned socket error status is zero on success, or one of the 124error codes listed here on failure. 125.It Bq Er EALREADY 126The socket is non-blocking 127and a previous connection attempt 128has not yet been completed. 129.El 130.Pp 131The following errors are specific to connecting names in the 132.Ux 133domain. 134These errors may not apply in future versions of the 135.Ux 136IPC domain. 137.Bl -tag -width Er 138.It Bq Er ENOTDIR 139A component of the path prefix is not a directory. 140.It Bq Er ENAMETOOLONG 141A component of a pathname exceeded 142.Dv {NAME_MAX} 143characters, or an entire path name exceeded 144.Dv {PATH_MAX} 145characters. 146.It Bq Er ENOENT 147The named socket does not exist. 148.It Bq Er EACCES 149Search permission is denied for a component of the path prefix, or 150write access to the named socket is denied. 151.It Bq Er ELOOP 152Too many symbolic links were encountered in translating the pathname. 153.El 154.Sh SEE ALSO 155.Xr accept 2 , 156.Xr getsockname 2 , 157.Xr getsockopt 2 , 158.Xr poll 2 , 159.Xr select 2 , 160.Xr socket 2 161.Sh HISTORY 162The 163.Fn connect 164function call appeared in 165.Bx 4.2 . 166