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<div class="title">ldns_struct_hdr Struct Reference</div> </div>
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<!-- doxytag: class="ldns_struct_hdr" -->
<p>Header of a dns packet.
<a href="structldns__struct__hdr.html#details">More...</a></p>
<table class="memberdecls">
<tr><td colspan="2"><h2><a name="pub-attribs"></a>
Data Fields</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">uint16_t </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#a0ae245aee47aeaff6752c5838bfe0c43">_id</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Id of a packet. <a href="#a0ae245aee47aeaff6752c5838bfe0c43"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#aba1c86565df77ef613f30b4fee22dc5f">_qr</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Query bit (0=query, 1=answer) <a href="#aba1c86565df77ef613f30b4fee22dc5f"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#ab30f4c6cf148cd8f11421872f02541e0">_aa</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Authoritative answer. <a href="#ab30f4c6cf148cd8f11421872f02541e0"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#acca290e74f3f3ad1e2a295ac015aa447">_tc</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Packet truncated. <a href="#acca290e74f3f3ad1e2a295ac015aa447"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#a5d537b5c7ab758c6289f050c90d52d61">_rd</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Recursion desired. <a href="#a5d537b5c7ab758c6289f050c90d52d61"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#a998ad0bf461438d8e0352350c3862c22">_cd</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Checking disabled. <a href="#a998ad0bf461438d8e0352350c3862c22"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#ad24aac22ef23f99a1067f050de6fcd9c">_ra</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Recursion available. <a href="#ad24aac22ef23f99a1067f050de6fcd9c"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#abdb3ed5a171e465d06563c6ce382410b">_ad</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Authentic data. <a href="#abdb3ed5a171e465d06563c6ce382410b"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="packet_8h.html#a9108e104c619091d0f83381cfc1ea64b">ldns_pkt_opcode</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#a104ead3c495c531fed1a1197a0d78ca3">_opcode</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Query type. <a href="#a104ead3c495c531fed1a1197a0d78ca3"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">uint8_t </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#ab90c9e6ed5a4f2d68f4f08d49824c998">_rcode</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Response code. <a href="#ab90c9e6ed5a4f2d68f4f08d49824c998"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">uint16_t </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#a74f241812561c2d4f9207c50c38b1140">_qdcount</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">question sec <a href="#a74f241812561c2d4f9207c50c38b1140"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">uint16_t </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#a3b3b9eaa3b71d5338316f00490d3cac5">_ancount</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">answer sec <a href="#a3b3b9eaa3b71d5338316f00490d3cac5"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">uint16_t </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#abcff0f5bc5adaeef5b527ce4750d0f45">_nscount</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">auth sec <a href="#abcff0f5bc5adaeef5b527ce4750d0f45"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">uint16_t </td><td class="memItemRight" valign="bottom"><a class="el" href="structldns__struct__hdr.html#aa0af70f67e604e91536d9fdac85ba8c8">_arcount</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">add sec <a href="#aa0af70f67e604e91536d9fdac85ba8c8"></a><br/></td></tr>
</table>
<hr/><a name="details" id="details"></a><h2>Detailed Description</h2>
<div class="textblock"><p>Header of a dns packet. </p>
<p>Contains the information about the packet itself, as specified in RFC1035 </p>
<pre>
4.1.1. Header section format</pre><pre>The header contains the following fields:</pre><pre> 1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ID |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|QR| Opcode |AA|TC|RD|RA| Z | RCODE |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| QDCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ANCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| NSCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ARCOUNT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+</pre><pre>where:</pre><pre>ID A 16 bit identifier assigned by the program that
generates any kind of query. This identifier is copied
the corresponding reply and can be used by the requester
to match up replies to outstanding queries.</pre><pre>QR A one bit field that specifies whether this message is a
query (0), or a response (1).</pre><pre>OPCODE A four bit field that specifies kind of query in this
message. This value is set by the originator of a query
and copied into the response. The values are:</pre><pre> 0 a standard query (QUERY)</pre><pre> 1 an inverse query (IQUERY)</pre><pre> 2 a server status request (STATUS)</pre><pre> 3-15 reserved for future use</pre><pre>AA Authoritative Answer - this bit is valid in responses,
and specifies that the responding name server is an
authority for the domain name in question section.</pre><pre> Note that the contents of the answer section may have
multiple owner names because of aliases. The AA bit</pre><pre> corresponds to the name which matches the query name, or
the first owner name in the answer section.</pre><pre>TC TrunCation - specifies that this message was truncated
due to length greater than that permitted on the
transmission channel.</pre><pre>RD Recursion Desired - this bit may be set in a query and
is copied into the response. If RD is set, it directs
the name server to pursue the query recursively.
Recursive query support is optional.</pre><pre>RA Recursion Available - this be is set or cleared in a
response, and denotes whether recursive query support is
available in the name server.</pre><pre>Z Reserved for future use. Must be zero in all queries
and responses.</pre><pre>RCODE Response code - this 4 bit field is set as part of
responses. The values have the following
interpretation:</pre><pre> 0 No error condition</pre><pre> 1 Format error - The name server was
unable to interpret the query.</pre><pre> 2 Server failure - The name server was
unable to process this query due to a
problem with the name server.</pre><pre> 3 Name Error - Meaningful only for
responses from an authoritative name
server, this code signifies that the
domain name referenced in the query does
not exist.</pre><pre> 4 Not Implemented - The name server does
not support the requested kind of query.</pre><pre> 5 Refused - The name server refuses to
perform the specified operation for
policy reasons. For example, a name
server may not wish to provide the
information to the particular requester,
or a name server may not wish to perform
a particular operation (e.g., zone</pre><pre> transfer) for particular data.</pre><pre> 6-15 Reserved for future use.</pre><pre>QDCOUNT an unsigned 16 bit integer specifying the number of
entries in the question section.</pre><pre>ANCOUNT an unsigned 16 bit integer specifying the number of
resource records in the answer section.</pre><pre>NSCOUNT an unsigned 16 bit integer specifying the number of name
server resource records in the authority records
section.</pre><pre>ARCOUNT an unsigned 16 bit integer specifying the number of
resource records in the additional records section.</pre><pre></pre>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00192">192</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
</div><hr/><h2>Field Documentation</h2>
<a class="anchor" id="a0ae245aee47aeaff6752c5838bfe0c43"></a><!-- doxytag: member="ldns_struct_hdr::_id" ref="a0ae245aee47aeaff6752c5838bfe0c43" args="" -->
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<td class="memname">uint16_t <a class="el" href="structldns__struct__hdr.html#a0ae245aee47aeaff6752c5838bfe0c43">ldns_struct_hdr::_id</a></td>
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<p>Id of a packet. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00195">195</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="aba1c86565df77ef613f30b4fee22dc5f"></a><!-- doxytag: member="ldns_struct_hdr::_qr" ref="aba1c86565df77ef613f30b4fee22dc5f" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#aba1c86565df77ef613f30b4fee22dc5f">ldns_struct_hdr::_qr</a></td>
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<p>Query bit (0=query, 1=answer) </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00197">197</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="ab30f4c6cf148cd8f11421872f02541e0"></a><!-- doxytag: member="ldns_struct_hdr::_aa" ref="ab30f4c6cf148cd8f11421872f02541e0" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#ab30f4c6cf148cd8f11421872f02541e0">ldns_struct_hdr::_aa</a></td>
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<p>Authoritative answer. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00199">199</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="acca290e74f3f3ad1e2a295ac015aa447"></a><!-- doxytag: member="ldns_struct_hdr::_tc" ref="acca290e74f3f3ad1e2a295ac015aa447" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#acca290e74f3f3ad1e2a295ac015aa447">ldns_struct_hdr::_tc</a></td>
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<p>Packet truncated. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00201">201</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="a5d537b5c7ab758c6289f050c90d52d61"></a><!-- doxytag: member="ldns_struct_hdr::_rd" ref="a5d537b5c7ab758c6289f050c90d52d61" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#a5d537b5c7ab758c6289f050c90d52d61">ldns_struct_hdr::_rd</a></td>
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<p>Recursion desired. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00203">203</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="a998ad0bf461438d8e0352350c3862c22"></a><!-- doxytag: member="ldns_struct_hdr::_cd" ref="a998ad0bf461438d8e0352350c3862c22" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#a998ad0bf461438d8e0352350c3862c22">ldns_struct_hdr::_cd</a></td>
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<p>Checking disabled. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00205">205</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="ad24aac22ef23f99a1067f050de6fcd9c"></a><!-- doxytag: member="ldns_struct_hdr::_ra" ref="ad24aac22ef23f99a1067f050de6fcd9c" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#ad24aac22ef23f99a1067f050de6fcd9c">ldns_struct_hdr::_ra</a></td>
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<p>Recursion available. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00207">207</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="abdb3ed5a171e465d06563c6ce382410b"></a><!-- doxytag: member="ldns_struct_hdr::_ad" ref="abdb3ed5a171e465d06563c6ce382410b" args="" -->
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<td class="memname">bool <a class="el" href="structldns__struct__hdr.html#abdb3ed5a171e465d06563c6ce382410b">ldns_struct_hdr::_ad</a></td>
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<p>Authentic data. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00209">209</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="a104ead3c495c531fed1a1197a0d78ca3"></a><!-- doxytag: member="ldns_struct_hdr::_opcode" ref="a104ead3c495c531fed1a1197a0d78ca3" args="" -->
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<td class="memname"><a class="el" href="packet_8h.html#a9108e104c619091d0f83381cfc1ea64b">ldns_pkt_opcode</a> <a class="el" href="structldns__struct__hdr.html#a104ead3c495c531fed1a1197a0d78ca3">ldns_struct_hdr::_opcode</a></td>
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<p>Query type. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00211">211</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<a class="anchor" id="ab90c9e6ed5a4f2d68f4f08d49824c998"></a><!-- doxytag: member="ldns_struct_hdr::_rcode" ref="ab90c9e6ed5a4f2d68f4f08d49824c998" args="" -->
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<td class="memname">uint8_t <a class="el" href="structldns__struct__hdr.html#ab90c9e6ed5a4f2d68f4f08d49824c998">ldns_struct_hdr::_rcode</a></td>
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<p>Response code. </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00213">213</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<p>question sec </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00215">215</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<p>answer sec </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00217">217</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<p>auth sec </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00219">219</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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<p>add sec </p>
<p>Definition at line <a class="el" href="packet_8h_source.html#l00221">221</a> of file <a class="el" href="packet_8h_source.html">packet.h</a>.</p>
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