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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>5. Adding new DNS record types</title><link rel="stylesheet" href="docbook.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="PowerDNS manual" /><link rel="up" href="pdns-internals.html" title="Appendix B. PDNS internals" /><link rel="prev" href="dns-to-query.html" title="4. How PDNS translates DNS queries into backend queries" /><link rel="next" href="backend-writers-guide.html" title="Appendix C. Backend writers' guide" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5. Adding new DNS record types</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="dns-to-query.html">Prev</a> </td><th width="60%" align="center">Appendix B. PDNS internals</th><td width="20%" align="right"> <a accesskey="n" href="backend-writers-guide.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="5. Adding new DNS record types"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="adding-rr-types"></a>5. Adding new DNS record types</h2></div></div></div><p>
Here are the full descriptions on how we added the TLSA record type to all PowerDNS products, with links to the actual source code.
</p><p>
First, define the TLSARecordContent class in <a class="ulink" href="http://wiki.powerdns.com/trac/browser/trunk/pdns/pdns/dnsrecords.hh?rev=2338#L307" target="_top">dnsrecords.hh</a>:
</p><pre class="screen">
class TLSARecordContent : public DNSRecordContent
{
public:
includeboilerplate(TLSA)
uint8_t d_certusage, d_selector, d_matchtype;
string d_cert;
};
</pre><p>
The 'includeboilerplate(TLSA)' generates the four methods that do everything PowerDNS would ever want to do with a record:
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
read TLSA records from zonefile format
</p></li><li class="listitem"><p>
write out a TLSA record in zonefile format
</p></li><li class="listitem"><p>
read a TLSA record from a packet
</p></li><li class="listitem"><p>
write a TLSA record to a packet
</p></li></ul></div><p>
</p><p>
The <a class="ulink" href="http://wiki.powerdns.com/trac/browser/trunk/pdns/pdns/dnsrecords.cc?rev=2638#L226" target="_top">actual parsing code</a>:
</p><pre class="screen">
boilerplate_conv(TLSA, 52,
conv.xfr8BitInt(d_certusage);
conv.xfr8BitInt(d_selector);
conv.xfr8BitInt(d_matchtype);
conv.xfrHexBlob(d_cert, true);
)
</pre><p>
This code defines the TLSA rrtype number as 52. Secondly, it says there are 3 eight bit fields for Certificate Usage, Selector and Match type. Next, it defines that the rest of the record is the actual certificate (hash). <a class="ulink" href="http://wiki.powerdns.com/trac/browser/trunk/pdns/pdns/dnsparser.hh?rev=2338#L70" target="_top">'conv'</a> methods are supplied for all DNS data types in use.
</p><p>
Now add TLSRecordContent::report() to <a class="ulink" href="http://wiki.powerdns.com/trac/browser/trunk/pdns/pdns/dnsrecords.cc?rev=2338#L364" target="_top">reportOtherTypes()</a>.
</p><p>
And that's it. For completeness, add TLSA and 52 to the QType enum in qtype.hh, which makes it easier to refer to the TLSA record in code if so required.
</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="dns-to-query.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="pdns-internals.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="backend-writers-guide.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">4. How PDNS translates DNS queries into backend queries </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Appendix C. Backend writers' guide</td></tr></table></div></body></html>
