1998-01-09 09:54:57 +03:00
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.\" $NetBSD: 4.t,v 1.2 1998/01/09 06:55:43 perry Exp $
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.\"
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1994-06-19 04:07:16 +04:00
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.\" Copyright (c) 1983, 1986, 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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.\" @(#)4.t 8.1 (Berkeley) 6/8/93
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.\"
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.nr H2 1
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.\".ds RH "Address representation
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.br
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.ne 2i
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.NH
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\s+2Internal address representation\s0
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.PP
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Common to all portions of the system are two data structures.
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These structures are used to represent
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addresses and various data objects.
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Addresses, internally are described by the \fIsockaddr\fP structure,
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.DS
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._f
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struct sockaddr {
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short sa_family; /* data format identifier */
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char sa_data[14]; /* address */
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};
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.DE
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All addresses belong to one or more \fIaddress families\fP
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which define their format and interpretation.
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The \fIsa_family\fP field indicates the address family to which the address
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belongs, and the \fIsa_data\fP field contains the actual data value.
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The size of the data field, 14 bytes, was selected based on a study
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of current address formats.*
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Specific address formats use private structure definitions
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that define the format of the data field.
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The system interface supports larger address structures,
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although address-family-independent support facilities, for example routing
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and raw socket interfaces, provide only 14 bytes for address storage.
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Protocols that do not use those facilities (e.g, the current Unix domain)
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may use larger data areas.
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.FS
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* Later versions of the system may support variable length addresses.
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.FE
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