summaryrefslogtreecommitdiff
path: root/doc/libs6dns/s6dns-ip46.html
blob: 58bdc58588797b178f43bf3e895277625d07cce3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
<html>
  <head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <meta http-equiv="Content-Language" content="en" />
    <title>s6-dns: the s6dns_ip46 library interface</title>
    <meta name="Description" content="s6-dns: the s6dns_ip46 library interface" />
    <meta name="Keywords" content="s6-dns dns s6dns_ip46 library libs6dns" />
    <!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> -->
  </head>
<body>

<p>
<a href="index.html">libs6dns</a><br />
<a href="../">s6-dns</a><br />
<a href="//skarnet.org/software/">Software</a><br />
<a href="//skarnet.org/">skarnet.org</a>
</p>

<h1> The <tt>s6dns_ip46</tt> library interface </h1>

<p>
 The following functions are declared in the <tt>s6-dns/s6dns-ip46.h</tt> header,
and implemented as macros.
</p>

<h2> General information </h2>

<p>
 <tt>s6dns_ip46</tt> is the transport abstraction layer. It allows
the functions declared in <a href="s6dns-engine.html">s6-dns/s6dns-engine.h</a>
and <a href="s6dns-rci.html">s6-dns/s6dns-rci.h</a> to be transport-agnostic,
i.e. to be able to work with both IPv4 and IPv6.
</p>

<p>
 If the underlying <a href="//skarnet.org/software/skalibs/">skalibs</a>
has been compiled with the
 <a href="//skarnet.org/software/skalibs/flags.html#noipv6">--disable-ipv6</a>
configure option,
or if it has detected at build time that the target host does not support
IPv6, then the s6dns-ip46 abstraction will be totally transparent and use
no resources at all.
</p>

<h2> Data structures </h2>

<p>
 A <tt>s6dns_ip46list_t</tt> structure holds a list of S6DNS_MAX_SERVERS (16)
IPv4 <em>or</em> IPv6 addresses. Such a mixed list can be constructed, for
instance, if the <tt>/etc/resolv.conf</tt> file contains both v4 and v6
<tt>nameserver</tt> lines.
</p>

<h2> Functions </h2>

<p>
 If <em>list</em> is a <tt>s6dns_ip46list_t</tt> and <em>i</em> an integer
between 0 and DNS_MAX_SERVERS-1, then
</p>

<ul>
 <li> <code>s6dns_ip46list_is6(&amp;list, i)</code> is 1 if the <em>i</em>th
address in <em>list</em> is IPv6 and 0 if it is IPv4. </li>
 <li> <code>s6dns_ip46list_ip(&amp;list, i)</code> is a <tt>char *</tt> pointer to
16 (if IPv6) or 4 (IPv4) bytes representing the <em>i</em>th address in
<em>list</em>, in network byte order. </li>
</ul>

</body>
</html>