/contrib/bind9/lib/lwres/man/lwres_noop.docbook
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- <refentry>
- <refentryinfo>
- <date>Jun 30, 2000</date>
- </refentryinfo>
- <refmeta>
- <refentrytitle>lwres_noop</refentrytitle>
- <manvolnum>3</manvolnum>
- <refmiscinfo>BIND9</refmiscinfo>
- </refmeta>
- <docinfo>
- <copyright>
- <year>2004</year>
- <year>2005</year>
- <year>2007</year>
- <year>2012</year>
- <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
- </copyright>
- <copyright>
- <year>2000</year>
- <year>2001</year>
- <holder>Internet Software Consortium.</holder>
- </copyright>
- </docinfo>
- <refnamediv>
- <refname>lwres_nooprequest_render</refname>
- <refname>lwres_noopresponse_render</refname>
- <refname>lwres_nooprequest_parse</refname>
- <refname>lwres_noopresponse_parse</refname>
- <refname>lwres_noopresponse_free</refname>
- <refname>lwres_nooprequest_free</refname>
- <refpurpose>lightweight resolver no-op message handling</refpurpose>
- </refnamediv>
- <refsynopsisdiv>
- <funcsynopsis>
- <funcsynopsisinfo>
- #include <lwres/lwres.h></funcsynopsisinfo>
- <funcprototype>
- <funcdef>
- lwres_result_t
- <function>lwres_nooprequest_render</function></funcdef>
- <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
- <paramdef>lwres_nooprequest_t *<parameter>req</parameter></paramdef>
- <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
- <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
- </funcprototype>
- <funcprototype>
- <funcdef>
- lwres_result_t
- <function>lwres_noopresponse_render</function></funcdef>
- <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
- <paramdef>lwres_noopresponse_t *<parameter>req</parameter></paramdef>
- <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
- <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
- </funcprototype>
- <funcprototype>
- <funcdef>
- lwres_result_t
- <function>lwres_nooprequest_parse</function></funcdef>
- <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
- <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
- <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
- <paramdef>lwres_nooprequest_t **<parameter>structp</parameter></paramdef>
- </funcprototype>
- <funcprototype>
- <funcdef>
- lwres_result_t
- <function>lwres_noopresponse_parse</function></funcdef>
- <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
- <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
- <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
- <paramdef>lwres_noopresponse_t **<parameter>structp</parameter></paramdef>
- </funcprototype>
- <funcprototype>
- <funcdef>
- void
- <function>lwres_noopresponse_free</function></funcdef>
- <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
- <paramdef>lwres_noopresponse_t **<parameter>structp</parameter></paramdef>
- </funcprototype>
- <funcprototype>
- <funcdef>
- void
- <function>lwres_nooprequest_free</function></funcdef>
- <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
- <paramdef>lwres_nooprequest_t **<parameter>structp</parameter></paramdef>
- </funcprototype>
- </funcsynopsis>
- </refsynopsisdiv>
- <refsect1>
- <title>DESCRIPTION</title>
- <para>
- These are low-level routines for creating and parsing
- lightweight resolver no-op request and response messages.
- </para>
- <para>
- The no-op message is analogous to a <command>ping</command>
- packet:
- a packet is sent to the resolver daemon and is simply echoed back.
- The opcode is intended to allow a client to determine if the server is
- operational or not.
- </para>
- <para>
- There are four main functions for the no-op opcode.
- One render function converts a no-op request structure —
- <type>lwres_nooprequest_t</type> —
- to the lighweight resolver's canonical format.
- It is complemented by a parse function that converts a packet in this
- canonical format to a no-op request structure.
- Another render function converts the no-op response structure —
- <type>lwres_noopresponse_t</type>
- to the canonical format.
- This is complemented by a parse function which converts a packet in
- canonical format to a no-op response structure.
- </para>
- <para>
- These structures are defined in
- <filename>lwres/lwres.h</filename>.
- They are shown below.
- </para>
- <para><programlisting>
- #define LWRES_OPCODE_NOOP 0x00000000U
- </programlisting>
- </para>
- <para><programlisting>
- typedef struct {
- lwres_uint16_t datalength;
- unsigned char *data;
- } lwres_nooprequest_t;
- </programlisting>
- </para>
- <para><programlisting>
- typedef struct {
- lwres_uint16_t datalength;
- unsigned char *data;
- } lwres_noopresponse_t;
- </programlisting>
- </para>
- <para>
- Although the structures have different types, they are identical.
- This is because the no-op opcode simply echos whatever data was sent:
- the response is therefore identical to the request.
- </para>
- <para><function>lwres_nooprequest_render()</function>
- uses resolver context <parameter>ctx</parameter> to convert
- no-op request structure <parameter>req</parameter> to canonical
- format. The packet header structure <parameter>pkt</parameter>
- is initialised and transferred to buffer
- <parameter>b</parameter>. The contents of
- <parameter>*req</parameter> are then appended to the buffer in
- canonical format.
- <function>lwres_noopresponse_render()</function> performs the
- same task, except it converts a no-op response structure
- <type>lwres_noopresponse_t</type> to the lightweight resolver's
- canonical format.
- </para>
- <para><function>lwres_nooprequest_parse()</function>
- uses context <parameter>ctx</parameter> to convert the contents
- of packet <parameter>pkt</parameter> to a
- <type>lwres_nooprequest_t</type> structure. Buffer
- <parameter>b</parameter> provides space to be used for storing
- this structure. When the function succeeds, the resulting
- <type>lwres_nooprequest_t</type> is made available through
- <parameter>*structp</parameter>.
- <function>lwres_noopresponse_parse()</function> offers the same
- semantics as <function>lwres_nooprequest_parse()</function>
- except it yields a <type>lwres_noopresponse_t</type> structure.
- </para>
- <para><function>lwres_noopresponse_free()</function>
- and <function>lwres_nooprequest_free()</function> release the
- memory in resolver context <parameter>ctx</parameter> that was
- allocated to the <type>lwres_noopresponse_t</type> or
- <type>lwres_nooprequest_t</type> structures referenced via
- <parameter>structp</parameter>.
- </para>
- </refsect1>
- <refsect1>
- <title>RETURN VALUES</title>
- <para>
- The no-op opcode functions
- <function>lwres_nooprequest_render()</function>,
- <function>lwres_noopresponse_render()</function>
- <function>lwres_nooprequest_parse()</function>
- and
- <function>lwres_noopresponse_parse()</function>
- all return
- <errorcode>LWRES_R_SUCCESS</errorcode>
- on success.
- They return
- <errorcode>LWRES_R_NOMEMORY</errorcode>
- if memory allocation fails.
- <errorcode>LWRES_R_UNEXPECTEDEND</errorcode>
- is returned if the available space in the buffer
- <parameter>b</parameter>
- is too small to accommodate the packet header or the
- <type>lwres_nooprequest_t</type>
- and
- <type>lwres_noopresponse_t</type>
- structures.
- <function>lwres_nooprequest_parse()</function>
- and
- <function>lwres_noopresponse_parse()</function>
- will return
- <errorcode>LWRES_R_UNEXPECTEDEND</errorcode>
- if the buffer is not empty after decoding the received packet.
- These functions will return
- <errorcode>LWRES_R_FAILURE</errorcode>
- if
- <constant>pktflags</constant>
- in the packet header structure
- <type>lwres_lwpacket_t</type>
- indicate that the packet is not a response to an earlier query.
- </para>
- </refsect1>
- <refsect1>
- <title>SEE ALSO</title>
- <para><citerefentry>
- <refentrytitle>lwres_packet</refentrytitle><manvolnum>3</manvolnum>
- </citerefentry>
- </para>
- </refsect1>
- </refentry><!--
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