00b67f09dd
Also known as ISC bind. This import adds utilities such as host(1), dig(1), and nslookup(1), as well as many other tools and libraries. Change-Id: I035ca46e64f1965d57019e773f4ff0ef035e4aa3
239 lines
8.6 KiB
Plaintext
239 lines
8.6 KiB
Plaintext
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
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[<!ENTITY mdash "—">]>
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<!--
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- Copyright (C) 2004, 2005, 2007, 2014 Internet Systems Consortium, Inc. ("ISC")
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- Copyright (C) 2000, 2001 Internet Software Consortium.
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-
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- Permission to use, copy, modify, and/or distribute this software for any
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- purpose with or without fee is hereby granted, provided that the above
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- copyright notice and this permission notice appear in all copies.
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-
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- THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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- AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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- PERFORMANCE OF THIS SOFTWARE.
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-->
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<refentry>
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<refentryinfo>
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<date>June 18, 2007</date>
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</refentryinfo>
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<refmeta>
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<refentrytitle>lwres_resutil</refentrytitle>
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<manvolnum>3</manvolnum>
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<refmiscinfo>BIND9</refmiscinfo>
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</refmeta>
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<docinfo>
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<copyright>
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<year>2004</year>
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<year>2005</year>
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<year>2007</year>
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<year>2014</year>
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<holder>Internet Systems Consortium, Inc. ("ISC")</holder>
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</copyright>
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<copyright>
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<year>2000</year>
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<year>2001</year>
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<holder>Internet Software Consortium.</holder>
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</copyright>
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</docinfo>
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<refnamediv>
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<refname>lwres_string_parse</refname>
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<refname>lwres_addr_parse</refname>
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<refname>lwres_getaddrsbyname</refname>
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<refname>lwres_getnamebyaddr</refname>
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<refpurpose>lightweight resolver utility functions</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <lwres/lwres.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>
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lwres_result_t
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<function>lwres_string_parse</function></funcdef>
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<paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
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<paramdef>char **<parameter>c</parameter></paramdef>
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<paramdef>lwres_uint16_t *<parameter>len</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>
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lwres_result_t
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<function>lwres_addr_parse</function></funcdef>
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<paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
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<paramdef>lwres_addr_t *<parameter>addr</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>
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lwres_result_t
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<function>lwres_getaddrsbyname</function></funcdef>
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<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
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<paramdef>const char *<parameter>name</parameter></paramdef>
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<paramdef>lwres_uint32_t <parameter>addrtypes</parameter></paramdef>
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<paramdef>lwres_gabnresponse_t **<parameter>structp</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>
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lwres_result_t
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<function>lwres_getnamebyaddr</function></funcdef>
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<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
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<paramdef>lwres_uint32_t <parameter>addrtype</parameter></paramdef>
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<paramdef>lwres_uint16_t <parameter>addrlen</parameter></paramdef>
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<paramdef>const unsigned char *<parameter>addr</parameter></paramdef>
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<paramdef>lwres_gnbaresponse_t **<parameter>structp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>DESCRIPTION</title>
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<para><function>lwres_string_parse()</function>
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retrieves a DNS-encoded string starting the current pointer of
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lightweight resolver buffer <parameter>b</parameter>: i.e.
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<constant>b->current</constant>. When the function returns,
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the address of the first byte of the encoded string is returned
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via <parameter>*c</parameter> and the length of that string is
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given by <parameter>*len</parameter>. The buffer's current
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pointer is advanced to point at the character following the
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string length, the encoded string, and the trailing
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<type>NULL</type> character.
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</para>
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<para><function>lwres_addr_parse()</function>
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extracts an address from the buffer <parameter>b</parameter>.
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The buffer's current pointer <constant>b->current</constant>
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is presumed to point at an encoded address: the address preceded
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by a 32-bit protocol family identifier and a 16-bit length
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field. The encoded address is copied to
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<constant>addr->address</constant> and
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<constant>addr->length</constant> indicates the size in bytes
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of the address that was copied.
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<constant>b->current</constant> is advanced to point at the
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next byte of available data in the buffer following the encoded
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address.
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</para>
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<para><function>lwres_getaddrsbyname()</function>
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and <function>lwres_getnamebyaddr()</function> use the
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<type>lwres_gnbaresponse_t</type> structure defined below:
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</para>
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<para><programlisting>
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typedef struct {
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lwres_uint32_t flags;
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lwres_uint16_t naliases;
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lwres_uint16_t naddrs;
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char *realname;
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char **aliases;
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lwres_uint16_t realnamelen;
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lwres_uint16_t *aliaslen;
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lwres_addrlist_t addrs;
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void *base;
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size_t baselen;
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} lwres_gabnresponse_t;
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</programlisting></para>
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<para>
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The contents of this structure are not manipulated directly but
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they are controlled through the
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<citerefentry>
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<refentrytitle>lwres_gabn</refentrytitle><manvolnum>3</manvolnum>
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</citerefentry>
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functions.
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</para>
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<para>
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The lightweight resolver uses
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<function>lwres_getaddrsbyname()</function> to perform
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forward lookups.
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Hostname <parameter>name</parameter> is looked up using the
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resolver
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context <parameter>ctx</parameter> for memory allocation.
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<parameter>addrtypes</parameter> is a bitmask indicating
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which type of
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addresses are to be looked up. Current values for this bitmask are
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<type>LWRES_ADDRTYPE_V4</type> for IPv4 addresses and
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<type>LWRES_ADDRTYPE_V6</type> for IPv6 addresses. Results of the
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lookup are returned in <parameter>*structp</parameter>.
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</para>
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<para><function>lwres_getnamebyaddr()</function>
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performs reverse lookups. Resolver context
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<parameter>ctx</parameter> is used for memory allocation. The
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address type is indicated by <parameter>addrtype</parameter>:
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<type>LWRES_ADDRTYPE_V4</type> or
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<type>LWRES_ADDRTYPE_V6</type>. The address to be looked up is
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given by <parameter>addr</parameter> and its length is
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<parameter>addrlen</parameter> bytes. The result of the
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function call is made available through
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<parameter>*structp</parameter>.
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</para>
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</refsect1>
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<refsect1>
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<title>RETURN VALUES</title>
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<para>
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Successful calls to
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<function>lwres_string_parse()</function>
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and
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<function>lwres_addr_parse()</function>
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return
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<errorcode>LWRES_R_SUCCESS.</errorcode>
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Both functions return
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<errorcode>LWRES_R_FAILURE</errorcode>
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if the buffer is corrupt or
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<errorcode>LWRES_R_UNEXPECTEDEND</errorcode>
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if the buffer has less space than expected for the components of the
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encoded string or address.
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</para>
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<para><function>lwres_getaddrsbyname()</function>
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returns <errorcode>LWRES_R_SUCCESS</errorcode> on success and it
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returns <errorcode>LWRES_R_NOTFOUND</errorcode> if the hostname
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<parameter>name</parameter> could not be found.
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</para>
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<para><errorcode>LWRES_R_SUCCESS</errorcode>
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is returned by a successful call to
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<function>lwres_getnamebyaddr()</function>.
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</para>
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<para>
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Both
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<function>lwres_getaddrsbyname()</function>
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and
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<function>lwres_getnamebyaddr()</function>
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return
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<errorcode>LWRES_R_NOMEMORY</errorcode>
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when memory allocation requests fail and
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<errorcode>LWRES_R_UNEXPECTEDEND</errorcode>
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if the buffers used for sending queries and receiving replies are too
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small.
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</para>
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</refsect1>
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<refsect1>
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<title>SEE ALSO</title>
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<para><citerefentry>
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<refentrytitle>lwres_buffer</refentrytitle><manvolnum>3</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>lwres_gabn</refentrytitle><manvolnum>3</manvolnum>
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</citerefentry>.
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</para>
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</refsect1>
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</refentry><!--
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- Local variables:
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- mode: sgml
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- End:
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-->
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