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/contrib/bind9/lib/lwres/man/lwres_packet.docbook

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 21<!-- $Id$ -->
 22<refentry>
 23
 24  <refentryinfo>
 25    <date>Jun 30, 2000</date>
 26  </refentryinfo>
 27
 28  <refmeta>
 29    <refentrytitle>lwres_packet</refentrytitle>
 30    <manvolnum>3</manvolnum>
 31    <refmiscinfo>BIND9</refmiscinfo>
 32  </refmeta>
 33
 34  <docinfo>
 35    <copyright>
 36      <year>2004</year>
 37      <year>2005</year>
 38      <year>2007</year>
 39      <year>2012</year>
 40      <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
 41    </copyright>
 42    <copyright>
 43      <year>2000</year>
 44      <year>2001</year>
 45      <holder>Internet Software Consortium.</holder>
 46    </copyright>
 47  </docinfo>
 48
 49  <refnamediv>
 50    <refname>lwres_lwpacket_renderheader</refname>
 51    <refname>lwres_lwpacket_parseheader</refname>
 52    <refpurpose>lightweight resolver packet handling functions</refpurpose>
 53  </refnamediv>
 54  <refsynopsisdiv>
 55    <funcsynopsis>
 56<funcsynopsisinfo>#include &lt;lwres/lwpacket.h&gt;</funcsynopsisinfo>
 57<funcprototype>
 58        <funcdef>
 59lwres_result_t
 60<function>lwres_lwpacket_renderheader</function></funcdef>
 61        <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
 62        <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
 63        </funcprototype>
 64<funcprototype>
 65        <funcdef>
 66lwres_result_t
 67<function>lwres_lwpacket_parseheader</function></funcdef>
 68        <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
 69        <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
 70      </funcprototype>
 71</funcsynopsis>
 72  </refsynopsisdiv>
 73  <refsect1>
 74    <title>DESCRIPTION</title>
 75    <para>
 76      These functions rely on a
 77      <type>struct lwres_lwpacket</type>
 78      which is defined in
 79      <filename>lwres/lwpacket.h</filename>.
 80    </para>
 81
 82    <para><programlisting>
 83typedef struct lwres_lwpacket lwres_lwpacket_t;
 84      </programlisting>
 85    </para>
 86    <para><programlisting>
 87struct lwres_lwpacket {
 88        lwres_uint32_t          length;
 89        lwres_uint16_t          version;
 90        lwres_uint16_t          pktflags;
 91        lwres_uint32_t          serial;
 92        lwres_uint32_t          opcode;
 93        lwres_uint32_t          result;
 94        lwres_uint32_t          recvlength;
 95        lwres_uint16_t          authtype;
 96        lwres_uint16_t          authlength;
 97};
 98</programlisting>
 99    </para>
100
101    <para>
102      The elements of this structure are:
103      <variablelist>
104        <varlistentry>
105          <term><constant>length</constant></term>
106          <listitem>
107            <para>
108              the overall packet length, including the entire packet header.
109              This field is filled in by the lwres_gabn_*() and lwres_gnba_*()
110              calls.
111            </para>
112          </listitem>
113        </varlistentry>
114        <varlistentry>
115          <term><constant>version</constant></term>
116          <listitem>
117            <para>
118              the header format. There is currently only one format,
119              <type>LWRES_LWPACKETVERSION_0</type>.
120
121              This field is filled in by the lwres_gabn_*() and lwres_gnba_*()
122              calls.
123            </para>
124          </listitem>
125        </varlistentry>
126        <varlistentry>
127          <term><constant>pktflags</constant></term>
128          <listitem>
129            <para>
130              library-defined flags for this packet: for instance whether the
131              packet
132              is a request or a reply. Flag values can be set, but not defined
133              by
134              the caller.
135              This field is filled in by the application wit the exception of
136              the
137              LWRES_LWPACKETFLAG_RESPONSE bit, which is set by the library in
138              the
139              lwres_gabn_*() and lwres_gnba_*() calls.
140            </para>
141          </listitem>
142        </varlistentry>
143        <varlistentry>
144          <term><constant>serial</constant></term>
145          <listitem>
146            <para>
147              is set by the requestor and is returned in all replies. If two
148              or more
149              packets from the same source have the same serial number and are
150              from
151              the same source, they are assumed to be duplicates and the
152              latter ones
153              may be dropped.
154              This field must be set by the application.
155            </para>
156          </listitem>
157        </varlistentry>
158        <varlistentry>
159          <term><constant>opcode</constant></term>
160          <listitem>
161            <para>
162              indicates the operation.
163              Opcodes between 0x00000000 and 0x03ffffff are
164              reserved for use by the lightweight resolver library. Opcodes
165              between
166              0x04000000 and 0xffffffff are application defined.
167              This field is filled in by the lwres_gabn_*() and lwres_gnba_*()
168              calls.
169            </para>
170          </listitem>
171        </varlistentry>
172        <varlistentry>
173          <term><constant>result</constant></term>
174          <listitem>
175            <para>
176              is only valid for replies.
177              Results between 0x04000000 and 0xffffffff are application
178              defined.
179              Results between 0x00000000 and 0x03ffffff are reserved for
180              library use.
181              This field is filled in by the lwres_gabn_*() and lwres_gnba_*()
182              calls.
183            </para>
184          </listitem>
185        </varlistentry>
186        <varlistentry>
187          <term><constant>recvlength</constant></term>
188          <listitem>
189            <para>
190              is the maximum buffer size that the receiver can handle on
191              requests
192              and the size of the buffer needed to satisfy a request when the
193              buffer
194              is too large for replies.
195              This field is supplied by the application.
196            </para>
197          </listitem>
198        </varlistentry>
199        <varlistentry>
200          <term><constant>authtype</constant></term>
201          <listitem>
202            <para>
203              defines the packet level authentication that is used.
204              Authorisation types between 0x1000 and 0xffff are application
205              defined
206              and types between 0x0000 and 0x0fff are reserved for library
207              use.
208              Currently these are not used and must be zero.
209            </para>
210          </listitem>
211        </varlistentry>
212        <varlistentry>
213          <term><constant>authlen</constant></term>
214          <listitem>
215            <para>
216              gives the length of the authentication data.
217              Since packet authentication is currently not used, this must be
218              zero.
219            </para>
220          </listitem>
221        </varlistentry>
222      </variablelist>
223    </para>
224    <para>
225      The following opcodes are currently defined:
226      <variablelist>
227        <varlistentry>
228          <term><constant>NOOP</constant></term>
229          <listitem>
230            <para>
231              Success is always returned and the packet contents are echoed.
232              The lwres_noop_*() functions should be used for this type.
233            </para>
234          </listitem>
235        </varlistentry>
236        <varlistentry>
237          <term><constant>GETADDRSBYNAME</constant></term>
238          <listitem>
239            <para>
240              returns all known addresses for a given name.
241              The lwres_gabn_*() functions should be used for this type.
242            </para>
243          </listitem>
244        </varlistentry>
245        <varlistentry>
246          <term><constant>GETNAMEBYADDR</constant></term>
247          <listitem>
248            <para>
249              return the hostname for the given address.
250              The lwres_gnba_*() functions should be used for this type.
251            </para>
252          </listitem>
253        </varlistentry>
254      </variablelist>
255    </para>
256
257    <para><function>lwres_lwpacket_renderheader()</function>
258      transfers the contents of lightweight resolver packet structure
259      <type>lwres_lwpacket_t</type> <parameter>*pkt</parameter> in
260      network byte order to the lightweight resolver buffer,
261      <parameter>*b</parameter>.
262    </para>
263
264    <para><function>lwres_lwpacket_parseheader()</function>
265      performs the converse operation.  It transfers data in network
266      byte order from buffer <parameter>*b</parameter> to resolver
267      packet <parameter>*pkt</parameter>.  The contents of the buffer
268      <parameter>b</parameter> should correspond to a
269      <type>lwres_lwpacket_t</type>.
270    </para>
271
272  </refsect1>
273
274  <refsect1>
275    <title>RETURN VALUES</title>
276    <para>
277      Successful calls to
278      <function>lwres_lwpacket_renderheader()</function> and
279      <function>lwres_lwpacket_parseheader()</function> return
280      <errorcode>LWRES_R_SUCCESS</errorcode>.  If there is insufficient
281      space to copy data between the buffer <parameter>*b</parameter> and
282      lightweight resolver packet <parameter>*pkt</parameter> both
283      functions
284      return <errorcode>LWRES_R_UNEXPECTEDEND</errorcode>.
285    </para>
286
287  </refsect1>
288</refentry><!--
289 - Local variables:
290 - mode: sgml
291 - End:
292-->