d6fa26d0adaec6c910115be34fe7a5a5f402c14fMark Andrews<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<a name="id-1"></a><div class="titlepage"></div>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User lwres_string_parse,
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User lwres_addr_parse,
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User lwres_getaddrsbyname,
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User lwres_getnamebyaddr
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User — lightweight resolver utility functions
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<pre class="funcsynopsisinfo">#include <lwres/lwres.h></pre>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austeinlwres_result_t
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<b class="fsfunc">lwres_string_parse</b>(</code></td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_buffer_t *<var class="pdparam">b</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>char **<var class="pdparam">c</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_uint16_t *<var class="pdparam">len</var><code>)</code>;</td>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austeinlwres_result_t
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<b class="fsfunc">lwres_addr_parse</b>(</code></td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_buffer_t *<var class="pdparam">b</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_addr_t *<var class="pdparam">addr</var><code>)</code>;</td>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austeinlwres_result_t
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<b class="fsfunc">lwres_getaddrsbyname</b>(</code></td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>const char *<var class="pdparam">name</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_uint32_t <var class="pdparam">addrtypes</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_gabnresponse_t **<var class="pdparam">structp</var><code>)</code>;</td>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austeinlwres_result_t
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein<b class="fsfunc">lwres_getnamebyaddr</b>(</code></td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_uint32_t <var class="pdparam">addrtype</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_uint16_t <var class="pdparam">addrlen</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>const unsigned char *<var class="pdparam">addr</var>, </td>
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<td>lwres_gnbaresponse_t **<var class="pdparam">structp</var><code>)</code>;</td>
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><code class="function">lwres_string_parse()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein retrieves a DNS-encoded string starting the current pointer of
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein lightweight resolver buffer <em class="parameter"><code>b</code></em>: i.e.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="constant">b->current</code>. When the function returns,
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein the address of the first byte of the encoded string is returned
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein via <em class="parameter"><code>*c</code></em> and the length of that string is
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein given by <em class="parameter"><code>*len</code></em>. The buffer's current
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein pointer is advanced to point at the character following the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein string length, the encoded string, and the trailing
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><code class="function">lwres_addr_parse()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein extracts an address from the buffer <em class="parameter"><code>b</code></em>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The buffer's current pointer <code class="constant">b->current</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein is presumed to point at an encoded address: the address preceded
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein by a 32-bit protocol family identifier and a 16-bit length
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein field. The encoded address is copied to
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="constant">addr->address</code> and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="constant">addr->length</code> indicates the size in bytes
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein of the address that was copied.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="constant">b->current</code> is advanced to point at the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein next byte of available data in the buffer following the encoded
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><code class="function">lwres_getaddrsbyname()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein and <code class="function">lwres_getnamebyaddr()</code> use the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="type">lwres_gnbaresponse_t</span> structure defined below:
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austeintypedef struct {
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint32_t flags;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint16_t naliases;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint16_t naddrs;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson char *realname;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson char **aliases;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint16_t realnamelen;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint16_t *aliaslen;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_addrlist_t addrs;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson size_t baselen;
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein} lwres_gabnresponse_t;
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The contents of this structure are not manipulated directly but
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein they are controlled through the
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <span class="refentrytitle">lwres_gabn</span>(3)
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein The lightweight resolver uses
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="function">lwres_getaddrsbyname()</code> to perform
a24330c4805a224191ab687d0291963062fe3355Tinderbox User forward lookups.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Hostname <em class="parameter"><code>name</code></em> is looked up using the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein context <em class="parameter"><code>ctx</code></em> for memory allocation.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>addrtypes</code></em> is a bitmask indicating
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein which type of
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein addresses are to be looked up. Current values for this bitmask are
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="type">LWRES_ADDRTYPE_V4</span> for IPv4 addresses and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="type">LWRES_ADDRTYPE_V6</span> for IPv6 addresses. Results of the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein lookup are returned in <em class="parameter"><code>*structp</code></em>.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><code class="function">lwres_getnamebyaddr()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein performs reverse lookups. Resolver context
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>ctx</code></em> is used for memory allocation. The
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein address type is indicated by <em class="parameter"><code>addrtype</code></em>:
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="type">LWRES_ADDRTYPE_V6</span>. The address to be looked up is
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein given by <em class="parameter"><code>addr</code></em> and its length is
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>addrlen</code></em> bytes. The result of the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein function call is made available through
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>*structp</code></em>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Successful calls to
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="function">lwres_string_parse()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="function">lwres_addr_parse()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein Both functions return
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein if the buffer is corrupt or
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein if the buffer has less space than expected for the components of the
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein encoded string or address.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><code class="function">lwres_getaddrsbyname()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein returns <span class="errorcode">LWRES_R_SUCCESS</span> on success and it
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein returns <span class="errorcode">LWRES_R_NOTFOUND</span> if the hostname
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <em class="parameter"><code>name</code></em> could not be found.
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <p><span class="errorcode">LWRES_R_SUCCESS</span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein is returned by a successful call to
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="function">lwres_getnamebyaddr()</code>.
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="function">lwres_getaddrsbyname()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <code class="function">lwres_getnamebyaddr()</code>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein when memory allocation requests fail and
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
60e5e10f8d2e2b0c41e8abad38cacd867caa6ab2Rob Austein if the buffers used for sending queries and receiving replies are too
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <span class="refentrytitle">lwres_buffer</span>(3)
7911e6f9de303bca5a3d8b34f4330c8f7cecffaeTinderbox User <span class="refentrytitle">lwres_gabn</span>(3)