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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<!-- lifted from troff+man by doclifter -->
<refentry>
<refmeta>
<refentrytitle>IPSEC_RANGETOSUBNET</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo class='date'>8 Sept 2000</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>ipsec rangetosubnet</refname>
<refpurpose>convert address range to subnet</refpurpose>
</refnamediv>
<!-- body begins here -->
<refsynopsisdiv id='synopsis'>
<funcsynopsis>
<funcsynopsisinfo>
#include <freeswan.h>
</funcsynopsisinfo>
<funcprototype>
<funcdef>const char *<function>rangetosubnet</function></funcdef>
<paramdef>const ip_address * <parameter>start</parameter></paramdef>
<paramdef>const ip_address * <parameter>stop</parameter></paramdef>
<paramdef>ip_subnet * <parameter>dst</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id='description'><title>DESCRIPTION</title>
<para><emphasis remap='I'>Rangetosubnet</emphasis>
accepts two IP addresses which define an address range,
from
<varname role='parameter'>start</varname>
to
<varname role='parameter'>stop</varname>
inclusive,
and converts this to a subnet if possible.
The addresses must both be IPv4 or both be IPv6,
and the address family of the resulting subnet is the same.</para>
<para><emphasis remap='I'>Rangetosubnet</emphasis>
returns NULL for success and
a pointer to a string-literal error message for failure;
see DIAGNOSTICS.</para>
</refsect1>
<refsect1 id='see_also'><title>SEE ALSO</title>
<para><citerefentry><refentrytitle>ipsec_initsubnet</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>ipsec_ttosubnet</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
</refsect1>
<refsect1 id='diagnostics'><title>DIAGNOSTICS</title>
<para>Fatal errors in
<function>rangetosubnet</function>
are:
mixed address families;
unknown address family;
<varname role='parameter'>start</varname>
and
<varname role='parameter'>stop</varname>
do not define a subnet.</para>
</refsect1>
<refsect1 id='history'><title>HISTORY</title>
<para>Written for the FreeS/WAN project by Henry Spencer.</para>
</refsect1>
<refsect1 id='bugs'><title>BUGS</title>
<para>The restriction of error reports to literal strings
(so that callers don't need to worry about freeing them or copying them)
does limit the precision of error reporting.</para>
<para>The error-reporting convention lends itself
to slightly obscure code,
because many readers will not think of NULL as signifying success.
A good way to make it clearer is to write something like:</para>
<!-- .RS -->
<literallayout remap='.nf'>
<emphasis remap='B'>const char *error;</emphasis>
<emphasis remap='B'>error = rangetosubnet( /* ... */ );</emphasis>
<emphasis remap='B'>if (error != NULL) {</emphasis>
<emphasis remap='B'> /* something went wrong */</emphasis>
</literallayout> <!-- .fi -->
</refsect1>
</refentry>
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