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<a name="DANE-API"></a>
<div class="header">
<p>
Next: <a href="Cryptographic-API.html#Cryptographic-API" accesskey="n" rel="next">Cryptographic API</a>, Previous: <a href="Abstract-key-API.html#Abstract-key-API" accesskey="p" rel="previous">Abstract key API</a>, Up: <a href="API-reference.html#API-reference" accesskey="u" rel="up">API reference</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="DANE-API-1"></a>
<h3 class="section">E.11 DANE API</h3>
<p>The following functions are to be used for DANE certificate verification.
Their prototypes lie in <samp>gnutls/dane.h</samp>. Note that you need to link
with the <code>libgnutls-dane</code> library to use them.
</p>
<a name="dane_005fcert_005ftype_005fname-1"></a>
<h4 class="subheading">dane_cert_type_name</h4>
<a name="dane_005fcert_005ftype_005fname"></a><dl>
<dt><a name="index-dane_005fcert_005ftype_005fname"></a>Function: <em>const char*</em> <strong>dane_cert_type_name</strong> <em>(dane_cert_type_t <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a DANE match type
</p>
<p>Convert a <code>dane_cert_type_t</code> value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
type, or <code>NULL</code> .
</p></dd></dl>
<a name="dane_005fcert_005fusage_005fname-1"></a>
<h4 class="subheading">dane_cert_usage_name</h4>
<a name="dane_005fcert_005fusage_005fname"></a><dl>
<dt><a name="index-dane_005fcert_005fusage_005fname"></a>Function: <em>const char*</em> <strong>dane_cert_usage_name</strong> <em>(dane_cert_usage_t <var>usage</var>)</em></dt>
<dd><p><var>usage</var>: – undescribed –
</p>
<p>Convert a <code>dane_cert_usage_t</code> value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
type, or <code>NULL</code> .
</p></dd></dl>
<a name="dane_005fmatch_005ftype_005fname-1"></a>
<h4 class="subheading">dane_match_type_name</h4>
<a name="dane_005fmatch_005ftype_005fname"></a><dl>
<dt><a name="index-dane_005fmatch_005ftype_005fname"></a>Function: <em>const char*</em> <strong>dane_match_type_name</strong> <em>(dane_match_type_t <var>type</var>)</em></dt>
<dd><p><var>type</var>: is a DANE match type
</p>
<p>Convert a <code>dane_match_type_t</code> value to a string.
</p>
<p><strong>Returns:</strong> a string that contains the name of the specified
type, or <code>NULL</code> .
</p></dd></dl>
<a name="dane_005fquery_005fdata-1"></a>
<h4 class="subheading">dane_query_data</h4>
<a name="dane_005fquery_005fdata"></a><dl>
<dt><a name="index-dane_005fquery_005fdata"></a>Function: <em>int</em> <strong>dane_query_data</strong> <em>(dane_query_t <var>q</var>, unsigned int <var>idx</var>, unsigned int * <var>usage</var>, unsigned int * <var>type</var>, unsigned int * <var>match</var>, gnutls_datum_t * <var>data</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p><var>idx</var>: The index of the query response.
</p>
<p><var>usage</var>: The certificate usage (see <code>dane_cert_usage_t</code> )
</p>
<p><var>type</var>: The certificate type (see <code>dane_cert_type_t</code> )
</p>
<p><var>match</var>: The DANE matching type (see <code>dane_match_type_t</code> )
</p>
<p><var>data</var>: The DANE data.
</p>
<p>This function will provide the DANE data from the query
response.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code> (0) is returned, otherwise a
negative error value.
</p></dd></dl>
<a name="dane_005fquery_005fdeinit-1"></a>
<h4 class="subheading">dane_query_deinit</h4>
<a name="dane_005fquery_005fdeinit"></a><dl>
<dt><a name="index-dane_005fquery_005fdeinit"></a>Function: <em>void</em> <strong>dane_query_deinit</strong> <em>(dane_query_t <var>q</var>)</em></dt>
<dd><p><var>q</var>: The structure to be deinitialized
</p>
<p>This function will deinitialize a DANE query result structure.
</p></dd></dl>
<a name="dane_005fquery_005fentries-1"></a>
<h4 class="subheading">dane_query_entries</h4>
<a name="dane_005fquery_005fentries"></a><dl>
<dt><a name="index-dane_005fquery_005fentries"></a>Function: <em>unsigned int</em> <strong>dane_query_entries</strong> <em>(dane_query_t <var>q</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p>This function will return the number of entries in a query.
</p>
<p><strong>Returns:</strong> The number of entries.
</p></dd></dl>
<a name="dane_005fquery_005fstatus-1"></a>
<h4 class="subheading">dane_query_status</h4>
<a name="dane_005fquery_005fstatus"></a><dl>
<dt><a name="index-dane_005fquery_005fstatus"></a>Function: <em>dane_query_status_t</em> <strong>dane_query_status</strong> <em>(dane_query_t <var>q</var>)</em></dt>
<dd><p><var>q</var>: The query result structure
</p>
<p>This function will return the status of the query response.
See <code>dane_query_status_t</code> for the possible types.
</p>
<p><strong>Returns:</strong> The status type.
</p></dd></dl>
<a name="dane_005fquery_005ftlsa-1"></a>
<h4 class="subheading">dane_query_tlsa</h4>
<a name="dane_005fquery_005ftlsa"></a><dl>
<dt><a name="index-dane_005fquery_005ftlsa"></a>Function: <em>int</em> <strong>dane_query_tlsa</strong> <em>(dane_state_t <var>s</var>, dane_query_t * <var>r</var>, const char* <var>host</var>, const char* <var>proto</var>, unsigned int <var>port</var>)</em></dt>
<dd><p><var>s</var>: The DANE state structure
</p>
<p><var>r</var>: A structure to place the result
</p>
<p><var>host</var>: The host name to resolve.
</p>
<p><var>proto</var>: The protocol type (tcp, udp, etc.)
</p>
<p><var>port</var>: The service port number (eg. 443).
</p>
<p>This function will query the DNS server for the TLSA (DANE)
data for the given host.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code> (0) is returned, otherwise a
negative error value.
</p></dd></dl>
<a name="dane_005fstate_005fdeinit-1"></a>
<h4 class="subheading">dane_state_deinit</h4>
<a name="dane_005fstate_005fdeinit"></a><dl>
<dt><a name="index-dane_005fstate_005fdeinit"></a>Function: <em>void</em> <strong>dane_state_deinit</strong> <em>(dane_state_t <var>s</var>)</em></dt>
<dd><p><var>s</var>: The structure to be deinitialized
</p>
<p>This function will deinitialize a DANE query structure.
</p></dd></dl>
<a name="dane_005fstate_005finit-1"></a>
<h4 class="subheading">dane_state_init</h4>
<a name="dane_005fstate_005finit"></a><dl>
<dt><a name="index-dane_005fstate_005finit"></a>Function: <em>int</em> <strong>dane_state_init</strong> <em>(dane_state_t* <var>s</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>s</var>: The structure to be initialized
</p>
<p><var>flags</var>: flags from the <code>dane_state_flags</code> enumeration
</p>
<p>This function will initialize a DANE query structure.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code> (0) is returned, otherwise a
negative error value.
</p></dd></dl>
<a name="dane_005fstate_005fset_005fdlv_005ffile-1"></a>
<h4 class="subheading">dane_state_set_dlv_file</h4>
<a name="dane_005fstate_005fset_005fdlv_005ffile"></a><dl>
<dt><a name="index-dane_005fstate_005fset_005fdlv_005ffile"></a>Function: <em>int</em> <strong>dane_state_set_dlv_file</strong> <em>(dane_state_t <var>s</var>, const char* <var>file</var>)</em></dt>
<dd><p><var>s</var>: The structure to be deinitialized
</p>
<p><var>file</var>: The file holding the DLV keys.
</p>
<p>This function will set a file with trusted keys
for DLV (DNSSEC Lookaside Validation).
</p></dd></dl>
<a name="dane_005fstrerror-1"></a>
<h4 class="subheading">dane_strerror</h4>
<a name="dane_005fstrerror"></a><dl>
<dt><a name="index-dane_005fstrerror"></a>Function: <em>const char *</em> <strong>dane_strerror</strong> <em>(int <var>error</var>)</em></dt>
<dd><p><var>error</var>: is a DANE error code, a negative error code
</p>
<p>This function is similar to strerror. The difference is that it
accepts an error number returned by a gnutls function; In case of
an unknown error a descriptive string is sent instead of <code>NULL</code> .
</p>
<p>Error codes are always a negative error code.
</p>
<p><strong>Returns:</strong> A string explaining the DANE error message.
</p></dd></dl>
<a name="dane_005fverification_005fstatus_005fprint-1"></a>
<h4 class="subheading">dane_verification_status_print</h4>
<a name="dane_005fverification_005fstatus_005fprint"></a><dl>
<dt><a name="index-dane_005fverification_005fstatus_005fprint"></a>Function: <em>int</em> <strong>dane_verification_status_print</strong> <em>(unsigned int <var>status</var>, gnutls_datum_t * <var>out</var>, unsigned int <var>flags</var>)</em></dt>
<dd><p><var>status</var>: The status flags to be printed
</p>
<p><var>out</var>: Newly allocated datum with (0) terminated string.
</p>
<p><var>flags</var>: should be zero
</p>
<p>This function will pretty print the status of a verification
process – eg. the one obtained by <code>dane_verify_crt()</code> .
</p>
<p>The output <code>out</code> needs to be deallocated using <code>gnutls_free()</code> .
</p>
<p><strong>Returns:</strong> On success, <code>GNUTLS_E_SUCCESS</code> (0) is returned, otherwise a
negative error value.
</p></dd></dl>
<a name="dane_005fverify_005fcrt-1"></a>
<h4 class="subheading">dane_verify_crt</h4>
<a name="dane_005fverify_005fcrt"></a><dl>
<dt><a name="index-dane_005fverify_005fcrt-1"></a>Function: <em>int</em> <strong>dane_verify_crt</strong> <em>(dane_state_t <var>s</var>, const gnutls_datum_t * <var>chain</var>, unsigned <var>chain_size</var>, gnutls_certificate_type_t <var>chain_type</var>, const char * <var>hostname</var>, const char* <var>proto</var>, unsigned int <var>port</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>s</var>: A DANE state structure (may be NULL)
</p>
<p><var>chain</var>: A certificate chain
</p>
<p><var>chain_size</var>: The size of the chain
</p>
<p><var>chain_type</var>: The type of the certificate chain
</p>
<p><var>hostname</var>: The hostname associated with the chain
</p>
<p><var>proto</var>: The protocol of the service connecting (e.g. tcp)
</p>
<p><var>port</var>: The port of the service connecting (e.g. 443)
</p>
<p><var>sflags</var>: Flags for the the initialization of <code>s</code> (if NULL)
</p>
<p><var>vflags</var>: Verification flags; should be zero
</p>
<p><var>verify</var>: An OR’ed list of <code>dane_verify_status_t</code> .
</p>
<p>This function will verify the given certificate chain against the
CA constrains and/or the certificate available via DANE.
If no information via DANE can be obtained the flag <code>DANE_VERIFY_NO_DANE_INFO</code>
is set. If a DNSSEC signature is not available for the DANE
record then the verify flag <code>DANE_VERIFY_NO_DNSSEC_DATA</code> is set.
</p>
<p>Due to the many possible options of DANE, there is no single threat
model countered. When notifying the user about DANE verification results
it may be better to mention: DANE verification did not reject the certificate,
rather than mentioning a successful DANE verication.
</p>
<p>If the <code>q</code> parameter is provided it will be used for caching entries.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code> (0) is returned, otherwise a
negative error value.
</p></dd></dl>
<a name="dane_005fverify_005fsession_005fcrt-1"></a>
<h4 class="subheading">dane_verify_session_crt</h4>
<a name="dane_005fverify_005fsession_005fcrt"></a><dl>
<dt><a name="index-dane_005fverify_005fsession_005fcrt"></a>Function: <em>int</em> <strong>dane_verify_session_crt</strong> <em>(dane_state_t <var>s</var>, gnutls_session_t <var>session</var>, const char * <var>hostname</var>, const char* <var>proto</var>, unsigned int <var>port</var>, unsigned int <var>sflags</var>, unsigned int <var>vflags</var>, unsigned int * <var>verify</var>)</em></dt>
<dd><p><var>s</var>: A DANE state structure (may be NULL)
</p>
<p><var>session</var>: A gnutls session
</p>
<p><var>hostname</var>: The hostname associated with the chain
</p>
<p><var>proto</var>: The protocol of the service connecting (e.g. tcp)
</p>
<p><var>port</var>: The port of the service connecting (e.g. 443)
</p>
<p><var>sflags</var>: Flags for the the initialization of <code>s</code> (if NULL)
</p>
<p><var>vflags</var>: Verification flags; should be zero
</p>
<p><var>verify</var>: An OR’ed list of <code>dane_verify_status_t</code> .
</p>
<p>This function will verify session’s certificate chain against the
CA constrains and/or the certificate available via DANE.
See <code>dane_verify_crt()</code> for more information.
</p>
<p><strong>Returns:</strong> On success, <code>DANE_E_SUCCESS</code> (0) is returned, otherwise a
negative error value.
</p></dd></dl>
<hr>
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