174 lines
5.3 KiB
Groff
174 lines
5.3 KiB
Groff
.\" Copyright (c) 1983, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)connect.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd June 4, 1993
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.Dt CONNECT 2
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.Os
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.Sh NAME
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.Nm connect
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.Nd initiate a connection on a socket
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/socket.h>
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.Ft int
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.Fn connect "int s" "const struct sockaddr *name" "socklen_t namelen"
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.Sh DESCRIPTION
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The parameter
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.Fa s
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is a socket.
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If it is of type
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.Dv SOCK_DGRAM ,
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this call specifies the peer with which the socket is to be associated;
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this address is that to which datagrams are to be sent,
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and the only address from which datagrams are to be received.
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If the socket is of type
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.Dv SOCK_STREAM ,
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this call attempts to make a connection to
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another socket.
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The other socket is specified by
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.Fa name ,
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which is an address in the communications space of the socket.
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Each communications space interprets the
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.Fa name
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parameter in its own way.
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Generally, stream sockets may successfully
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.Fn connect
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only once; datagram sockets may use
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.Fn connect
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multiple times to change their association.
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Datagram sockets may dissolve the association
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by connecting to an invalid address, such as a null address.
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.Sh IMPLEMENTATION NOTES
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In the non-threaded library
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.Fn connect
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is implemented as the
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.Va connect
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syscall.
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.Pp
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In the threaded library, the
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.Va connect
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syscall is assembled to
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.Fn _thread_sys_connect
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and
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.Fn connect
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is implemented as a function which locks
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.Va s
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for read and write, then calls
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.Fn _thread_sys_connect .
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If the call to
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.Fn _thread_sys_connect
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would block, a context switch is performed.
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Before returning,
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.Fn connect
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unlocks
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.Va s .
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.Sh RETURN VALUES
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If the connection or binding succeeds, 0 is returned.
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Otherwise a -1 is returned, and a more specific error
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code is stored in
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.Va errno .
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.Sh ERRORS
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The
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.Fn connect
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call fails if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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.Fa s
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is not a valid descriptor.
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.It Bq Er ENOTSOCK
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.Fa s
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is a descriptor for a file, not a socket.
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.It Bq Er EADDRNOTAVAIL
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The specified address is not available on this machine.
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.It Bq Er EAFNOSUPPORT
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Addresses in the specified address family cannot be used with this socket.
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.It Bq Er EISCONN
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The socket is already connected.
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.It Bq Er ETIMEDOUT
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Connection establishment timed out without establishing a connection.
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.It Bq Er ECONNREFUSED
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The attempt to connect was forcefully rejected.
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.It Bq Er ENETUNREACH
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The network isn't reachable from this host.
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.It Bq Er EADDRINUSE
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The address is already in use.
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.It Bq Er EFAULT
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The
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.Fa name
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parameter specifies an area outside
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the process address space.
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.It Bq Er EINPROGRESS
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The socket is non-blocking
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and the connection cannot
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be completed immediately.
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It is possible to
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.Xr select 2
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for completion by selecting the socket for writing.
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.It Bq Er EALREADY
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The socket is non-blocking
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and a previous connection attempt
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has not yet been completed.
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.El
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.Pp
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The following errors are specific to connecting names in the UNIX domain.
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These errors may not apply in future versions of the UNIX IPC domain.
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded 255 characters,
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or an entire path name exceeded 1023 characters.
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.It Bq Er ENOENT
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The named socket does not exist.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er EACCES
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Write access to the named socket is denied.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.El
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.Sh SEE ALSO
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.Xr accept 2 ,
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.Xr getpeername 2 ,
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.Xr getsockname 2 ,
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.Xr select 2 ,
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.Xr socket 2
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.Sh HISTORY
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The
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.Fn connect
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function call appeared in
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.Bx 4.2 .
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