/contrib/bind9/lib/lwres/man/lwres_resutil.html
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- <html>
- <head>
- <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
- <title>lwres_resutil</title>
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- </head>
- <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
- <a name="id2476275"></a><div class="titlepage"></div>
- <div class="refnamediv">
- <h2>Name</h2>
- <p>lwres_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr — lightweight resolver utility functions</p>
- </div>
- <div class="refsynopsisdiv">
- <h2>Synopsis</h2>
- <div class="funcsynopsis">
- <pre class="funcsynopsisinfo">#include <lwres/lwres.h></pre>
- <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
- <tr>
- <td><code class="funcdef">
- lwres_result_t
- <b class="fsfunc">lwres_string_parse</b>(</code></td>
- <td>lwres_buffer_t * </td>
- <td>
- <var class="pdparam">b</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>char ** </td>
- <td>
- <var class="pdparam">c</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_uint16_t * </td>
- <td>
- <var class="pdparam">len</var><code>)</code>;</td>
- </tr>
- </table>
- <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
- <tr>
- <td><code class="funcdef">
- lwres_result_t
- <b class="fsfunc">lwres_addr_parse</b>(</code></td>
- <td>lwres_buffer_t * </td>
- <td>
- <var class="pdparam">b</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_addr_t * </td>
- <td>
- <var class="pdparam">addr</var><code>)</code>;</td>
- </tr>
- </table>
- <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
- <tr>
- <td><code class="funcdef">
- lwres_result_t
- <b class="fsfunc">lwres_getaddrsbyname</b>(</code></td>
- <td>lwres_context_t * </td>
- <td>
- <var class="pdparam">ctx</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>const char * </td>
- <td>
- <var class="pdparam">name</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_uint32_t </td>
- <td>
- <var class="pdparam">addrtypes</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_gabnresponse_t ** </td>
- <td>
- <var class="pdparam">structp</var><code>)</code>;</td>
- </tr>
- </table>
- <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
- <tr>
- <td><code class="funcdef">
- lwres_result_t
- <b class="fsfunc">lwres_getnamebyaddr</b>(</code></td>
- <td>lwres_context_t * </td>
- <td>
- <var class="pdparam">ctx</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_uint32_t </td>
- <td>
- <var class="pdparam">addrtype</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_uint16_t </td>
- <td>
- <var class="pdparam">addrlen</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>const unsigned char * </td>
- <td>
- <var class="pdparam">addr</var>, </td>
- </tr>
- <tr>
- <td> </td>
- <td>lwres_gnbaresponse_t ** </td>
- <td>
- <var class="pdparam">structp</var><code>)</code>;</td>
- </tr>
- </table>
- </div>
- </div>
- <div class="refsect1" lang="en">
- <a name="id2543470"></a><h2>DESCRIPTION</h2>
- <p><code class="function">lwres_string_parse()</code>
- retrieves a DNS-encoded string starting the current pointer of
- lightweight resolver buffer <em class="parameter"><code>b</code></em>: i.e.
- <code class="constant">b->current</code>. When the function returns,
- the address of the first byte of the encoded string is returned
- via <em class="parameter"><code>*c</code></em> and the length of that string is
- given by <em class="parameter"><code>*len</code></em>. The buffer's current
- pointer is advanced to point at the character following the
- string length, the encoded string, and the trailing
- <span class="type">NULL</span> character.
- </p>
- <p><code class="function">lwres_addr_parse()</code>
- extracts an address from the buffer <em class="parameter"><code>b</code></em>.
- The buffer's current pointer <code class="constant">b->current</code>
- is presumed to point at an encoded address: the address preceded
- by a 32-bit protocol family identifier and a 16-bit length
- field. The encoded address is copied to
- <code class="constant">addr->address</code> and
- <code class="constant">addr->length</code> indicates the size in bytes
- of the address that was copied.
- <code class="constant">b->current</code> is advanced to point at the
- next byte of available data in the buffer following the encoded
- address.
- </p>
- <p><code class="function">lwres_getaddrsbyname()</code>
- and <code class="function">lwres_getnamebyaddr()</code> use the
- <span class="type">lwres_gnbaresponse_t</span> structure defined below:
- </p>
- <pre class="programlisting">
- typedef struct {
- lwres_uint32_t flags;
- lwres_uint16_t naliases;
- lwres_uint16_t naddrs;
- char *realname;
- char **aliases;
- lwres_uint16_t realnamelen;
- lwres_uint16_t *aliaslen;
- lwres_addrlist_t addrs;
- void *base;
- size_t baselen;
- } lwres_gabnresponse_t;
- </pre>
- <p>
- The contents of this structure are not manipulated directly but
- they are controlled through the
- <span class="citerefentry"><span class="refentrytitle">lwres_gabn</span>(3)</span>
- functions.
- </p>
- <p>
- The lightweight resolver uses
- <code class="function">lwres_getaddrsbyname()</code> to perform
- foward lookups.
- Hostname <em class="parameter"><code>name</code></em> is looked up using the
- resolver
- context <em class="parameter"><code>ctx</code></em> for memory allocation.
- <em class="parameter"><code>addrtypes</code></em> is a bitmask indicating
- which type of
- addresses are to be looked up. Current values for this bitmask are
- <span class="type">LWRES_ADDRTYPE_V4</span> for IPv4 addresses and
- <span class="type">LWRES_ADDRTYPE_V6</span> for IPv6 addresses. Results of the
- lookup are returned in <em class="parameter"><code>*structp</code></em>.
- </p>
- <p><code class="function">lwres_getnamebyaddr()</code>
- performs reverse lookups. Resolver context
- <em class="parameter"><code>ctx</code></em> is used for memory allocation. The
- address type is indicated by <em class="parameter"><code>addrtype</code></em>:
- <span class="type">LWRES_ADDRTYPE_V4</span> or
- <span class="type">LWRES_ADDRTYPE_V6</span>. The address to be looked up is
- given by <em class="parameter"><code>addr</code></em> and its length is
- <em class="parameter"><code>addrlen</code></em> bytes. The result of the
- function call is made available through
- <em class="parameter"><code>*structp</code></em>.
- </p>
- </div>
- <div class="refsect1" lang="en">
- <a name="id2543609"></a><h2>RETURN VALUES</h2>
- <p>
- Successful calls to
- <code class="function">lwres_string_parse()</code>
- and
- <code class="function">lwres_addr_parse()</code>
- return
- <span class="errorcode">LWRES_R_SUCCESS.</span>
- Both functions return
- <span class="errorcode">LWRES_R_FAILURE</span>
- if the buffer is corrupt or
- <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
- if the buffer has less space than expected for the components of the
- encoded string or address.
- </p>
- <p><code class="function">lwres_getaddrsbyname()</code>
- returns <span class="errorcode">LWRES_R_SUCCESS</span> on success and it
- returns <span class="errorcode">LWRES_R_NOTFOUND</span> if the hostname
- <em class="parameter"><code>name</code></em> could not be found.
- </p>
- <p><span class="errorcode">LWRES_R_SUCCESS</span>
- is returned by a successful call to
- <code class="function">lwres_getnamebyaddr()</code>.
- </p>
- <p>
- Both
- <code class="function">lwres_getaddrsbyname()</code>
- and
- <code class="function">lwres_getnamebyaddr()</code>
- return
- <span class="errorcode">LWRES_R_NOMEMORY</span>
- when memory allocation requests fail and
- <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
- if the buffers used for sending queries and receiving replies are too
- small.
- </p>
- </div>
- <div class="refsect1" lang="en">
- <a name="id2543681"></a><h2>SEE ALSO</h2>
- <p><span class="citerefentry"><span class="refentrytitle">lwres_buffer</span>(3)</span>,
- <span class="citerefentry"><span class="refentrytitle">lwres_gabn</span>(3)</span>.
- </p>
- </div>
- </div></body>
- </html>