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  21 <title>Appendix D. BIND 9 DNS Library Support</title>
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  31 <tr><th colspan="3" align="center">Appendix D. BIND 9 DNS Library Support</th></tr>
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  42 <div class="appendix" lang="en">
  43 <div class="titlepage"><div><div><h2 class="title">
  44 <a name="Bv9ARM.ch12"></a>Appendix D. BIND 9 DNS Library Support</h2></div></div></div>
  45 <div class="toc">
  46 <p><b>Table of Contents</b></p>
  47 <dl>
  48 <dt><span class="sect1"><a href="Bv9ARM.ch12.html#bind9.library">BIND 9 DNS Library Support</a></span></dt>
  49 <dd><dl>
  50 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2612253">Prerequisite</a></span></dt>
  51 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2612263">Compilation</a></span></dt>
  52 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2612288">Installation</a></span></dt>
  53 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2612455">Known Defects/Restrictions</a></span></dt>
  54 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2612532">The dns.conf File</a></span></dt>
  55 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2612558">Sample Applications</a></span></dt>
  56 <dt><span class="sect2"><a href="Bv9ARM.ch12.html#id2613600">Library References</a></span></dt>
  57 </dl></dd>
  58 </dl>
  59 </div>
  60 <div class="sect1" lang="en">
  61 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
  62 <a name="bind9.library"></a>BIND 9 DNS Library Support</h2></div></div></div>
  63 <p>This version of BIND 9 "exports" its internal libraries so
  64   that they can be used by third-party applications more easily (we
  65   call them "export" libraries in this document). In addition to
  66   all major DNS-related APIs BIND 9 is currently using, the export
  67   libraries provide the following features:</p>
  68 <div class="itemizedlist"><ul type="disc">
  69 <li><p>The newly created "DNS client" module. This is a higher
  70       level API that provides an interface to name resolution,
  71       single DNS transaction with a particular server, and dynamic
  72       update. Regarding name resolution, it supports advanced
  73       features such as DNSSEC validation and caching. This module
  74       supports both synchronous and asynchronous mode.</p></li>
  75 <li><p>The new "IRS" (Information Retrieval System) library.
  76       It provides an interface to parse the traditional resolv.conf
  77       file and more advanced, DNS-specific configuration file for
  78       the rest of this package (see the description for the
  79       dns.conf file below).</p></li>
  80 <li><p>As part of the IRS library, newly implemented standard
  81       address-name mapping functions, getaddrinfo() and
  82       getnameinfo(), are provided. They use the DNSSEC-aware
  83       validating resolver backend, and could use other advanced
  84       features of the BIND 9 libraries such as caching. The
  85       getaddrinfo() function resolves both A and AAAA RRs
  86       concurrently (when the address family is unspecified).</p></li>
  87 <li><p>An experimental framework to support other event
  88       libraries than BIND 9's internal event task system.</p></li>
  89 </ul></div>
  90 <div class="sect2" lang="en">
  91 <div class="titlepage"><div><div><h3 class="title">
  92 <a name="id2612253"></a>Prerequisite</h3></div></div></div>
  93 <p>GNU make is required to build the export libraries (other
  94   part of BIND 9 can still be built with other types of make). In
  95   the reminder of this document, "make" means GNU make. Note that
  96   in some platforms you may need to invoke a different command name
  97   than "make" (e.g. "gmake") to indicate it's GNU make.</p>
  98 </div>
  99 <div class="sect2" lang="en">
 100 <div class="titlepage"><div><div><h3 class="title">
 101 <a name="id2612263"></a>Compilation</h3></div></div></div>
 102 <pre class="screen">
 103 $ <strong class="userinput"><code>./configure --enable-exportlib <em class="replaceable"><code>[other flags]</code></em></code></strong>
 104 $ <strong class="userinput"><code>make</code></strong>
 105 </pre>
 106 <p>
 107   This will create (in addition to usual BIND 9 programs) and a
 108   separate set of libraries under the lib/export directory. For
 109   example, <code class="filename">lib/export/dns/libdns.a</code> is the archive file of the
 110   export version of the BIND 9 DNS library. Sample application
 111   programs using the libraries will also be built under the
 112   lib/export/samples directory (see below).</p>
 113 </div>
 114 <div class="sect2" lang="en">
 115 <div class="titlepage"><div><div><h3 class="title">
 116 <a name="id2612288"></a>Installation</h3></div></div></div>
 117 <pre class="screen">
 118 $ <strong class="userinput"><code>cd lib/export</code></strong>
 119 $ <strong class="userinput"><code>make install</code></strong>
 120 </pre>
 121 <p>
 122   This will install library object files under the directory
 123   specified by the --with-export-libdir configure option (default:
 124   EPREFIX/lib/bind9), and header files under the directory
 125   specified by the --with-export-includedir configure option
 126   (default: PREFIX/include/bind9).
 127   Root privilege is normally required.
 128   "<span><strong class="command">make install</strong></span>" at the top directory will do the
 129   same.
 130   </p>
 131 <p>
 132   To see how to build your own
 133   application after the installation, see
 134   <code class="filename">lib/export/samples/Makefile-postinstall.in</code>.</p>
 135 </div>
 136 <div class="sect2" lang="en">
 137 <div class="titlepage"><div><div><h3 class="title">
 138 <a name="id2612455"></a>Known Defects/Restrictions</h3></div></div></div>
 139 <div class="itemizedlist"><ul type="disc">
 140 <li><p>Currently, win32 is not supported for the export
 141       library. (Normal BIND 9 application can be built as
 142       before).</p></li>
 143 <li>
 144 <p>The "fixed" RRset order is not (currently) supported in
 145       the export library. If you want to use "fixed" RRset order
 146       for, e.g. <span><strong class="command">named</strong></span> while still building the
 147       export library even without the fixed order support, build
 148       them separately:
 149       </p>
 150 <pre class="screen">
 151 $ <strong class="userinput"><code>./configure --enable-fixed-rrset <em class="replaceable"><code>[other flags, but not --enable-exportlib]</code></em></code></strong>
 152 $ <strong class="userinput"><code>make</code></strong>
 153 $ <strong class="userinput"><code>./configure --enable-exportlib <em class="replaceable"><code>[other flags, but not --enable-fixed-rrset]</code></em></code></strong>
 154 $ <strong class="userinput"><code>cd lib/export</code></strong>
 155 $ <strong class="userinput"><code>make</code></strong>
 156 </pre>
 157 <p>
 158     </p>
 159 </li>
 160 <li><p>The client module and the IRS library currently do not
 161       support DNSSEC validation using DLV (the underlying modules
 162       can handle it, but there is no tunable interface to enable
 163       the feature).</p></li>
 164 <li><p>RFC 5011 is not supported in the validating stub
 165       resolver of the export library. In fact, it is not clear
 166       whether it should: trust anchors would be a system-wide
 167       configuration which would be managed by an administrator,
 168       while the stub resolver will be used by ordinary applications
 169       run by a normal user.</p></li>
 170 <li><p>Not all common <code class="filename">/etc/resolv.conf</code>
 171       options are supported
 172       in the IRS library. The only available options in this
 173       version are "debug" and "ndots".</p></li>
 174 </ul></div>
 175 </div>
 176 <div class="sect2" lang="en">
 177 <div class="titlepage"><div><div><h3 class="title">
 178 <a name="id2612532"></a>The dns.conf File</h3></div></div></div>
 179 <p>The IRS library supports an "advanced" configuration file
 180   related to the DNS library for configuration parameters that
 181   would be beyond the capability of the
 182   <code class="filename">resolv.conf</code> file.
 183   Specifically, it is intended to provide DNSSEC related
 184   configuration parameters. By default the path to this
 185   configuration file is <code class="filename">/etc/dns.conf</code>.
 186   This module is very
 187   experimental and the configuration syntax or library interfaces
 188   may change in future versions. Currently, only the
 189   <span><strong class="command">trusted-keys</strong></span>
 190   statement is supported, whose syntax is the same as the same name
 191   of statement for <code class="filename">named.conf</code>. (See
 192   <a href="Bv9ARM.ch06.html#trusted-keys" title="trusted-keys Statement Grammar">the section called &#8220;<span><strong class="command">trusted-keys</strong></span> Statement Grammar&#8221;</a> for details.)</p>
 193 </div>
 194 <div class="sect2" lang="en">
 195 <div class="titlepage"><div><div><h3 class="title">
 196 <a name="id2612558"></a>Sample Applications</h3></div></div></div>
 197 <p>Some sample application programs using this API are
 198   provided for reference. The following is a brief description of
 199   these applications.
 200   </p>
 201 <div class="sect3" lang="en">
 202 <div class="titlepage"><div><div><h4 class="title">
 203 <a name="id2612567"></a>sample: a simple stub resolver utility</h4></div></div></div>
 204 <p>
 205   It sends a query of a given name (of a given optional RR type) to a
 206   specified recursive server, and prints the result as a list of
 207   RRs. It can also act as a validating stub resolver if a trust
 208   anchor is given via a set of command line options.</p>
 209 <p>
 210   Usage: sample [options] server_address hostname
 211   </p>
 212 <p>
 213   Options and Arguments:
 214   </p>
 215 <div class="variablelist"><dl>
 216 <dt><span class="term">
 217   -t RRtype
 218   </span></dt>
 219 <dd><p>
 220         specify the RR type of the query.  The default is the A RR.
 221   </p></dd>
 222 <dt><span class="term">
 223   [-a algorithm] [-e] -k keyname -K keystring
 224   </span></dt>
 225 <dd>
 226 <p>
 227         specify a command-line DNS key to validate the answer.  For
 228         example, to specify the following DNSKEY of example.com:
 229 </p>
 230 <div class="literallayout"><p><br>
 231                 example.com. 3600 IN DNSKEY 257 3 5 xxx<br>
 232 </p></div>
 233 <p>
 234         specify the options as follows:
 235 </p>
 236 <pre class="screen">
 237 <strong class="userinput"><code>
 238           -e -k example.com -K "xxx"
 239 </code></strong>
 240 </pre>
 241 <p>
 242         -e means that this key is a zone's "key signing key" (as known
 243         as "secure Entry point").
 244         When -a is omitted rsasha1 will be used by default.
 245   </p>
 246 </dd>
 247 <dt><span class="term">
 248   -s domain:alt_server_address
 249   </span></dt>
 250 <dd><p>
 251          specify a separate recursive server address for the specific
 252         "domain".  Example: -s example.com:2001:db8::1234
 253   </p></dd>
 254 <dt><span class="term">server_address</span></dt>
 255 <dd><p>
 256         an IP(v4/v6) address of the recursive server to which queries
 257         are sent.
 258   </p></dd>
 259 <dt><span class="term">hostname</span></dt>
 260 <dd><p>
 261         the domain name for the query
 262   </p></dd>
 263 </dl></div>
 264 </div>
 265 <div class="sect3" lang="en">
 266 <div class="titlepage"><div><div><h4 class="title">
 267 <a name="id2612658"></a>sample-async: a simple stub resolver, working asynchronously</h4></div></div></div>
 268 <p>
 269   Similar to "sample", but accepts a list
 270   of (query) domain names as a separate file and resolves the names
 271   asynchronously.</p>
 272 <p>
 273     Usage: sample-async [-s server_address] [-t RR_type] input_file</p>
 274 <p>
 275  Options and Arguments:
 276   </p>
 277 <div class="variablelist"><dl>
 278 <dt><span class="term">
 279    -s server_address
 280    </span></dt>
 281 <dd>
 282    an IPv4 address of the recursive server to which queries are sent.
 283   (IPv6 addresses are not supported in this implementation)
 284   </dd>
 285 <dt><span class="term">
 286    -t RR_type
 287   </span></dt>
 288 <dd>
 289   specify the RR type of the queries. The default is the A
 290   RR.
 291   </dd>
 292 <dt><span class="term">
 293    input_file
 294   </span></dt>
 295 <dd>
 296    a list of domain names to be resolved. each line
 297   consists of a single domain name. Example:
 298   <div class="literallayout"><p><br>
 299   www.example.com<br>
 300   mx.example.net<br>
 301   ns.xxx.example<br>
 302 </p></div>
 303 </dd>
 304 </dl></div>
 305 </div>
 306 <div class="sect3" lang="en">
 307 <div class="titlepage"><div><div><h4 class="title">
 308 <a name="id2612711"></a>sample-request: a simple DNS transaction client</h4></div></div></div>
 309 <p>
 310   It sends a query to a specified server, and
 311   prints the response with minimal processing. It doesn't act as a
 312   "stub resolver": it stops the processing once it gets any
 313   response from the server, whether it's a referral or an alias
 314   (CNAME or DNAME) that would require further queries to get the
 315   ultimate answer. In other words, this utility acts as a very
 316   simplified <span><strong class="command">dig</strong></span>.
 317   </p>
 318 <p>
 319   Usage: sample-request [-t RRtype] server_address hostname
 320   </p>
 321 <p>
 322     Options and Arguments:
 323   </p>
 324 <div class="variablelist"><dl>
 325 <dt><span class="term">
 326    -t RRtype
 327   </span></dt>
 328 <dd><p>
 329   specify the RR type of
 330   the queries. The default is the A RR.
 331   </p></dd>
 332 <dt><span class="term">
 333   server_address
 334   </span></dt>
 335 <dd><p>
 336    an IP(v4/v6)
 337   address of the recursive server to which the query is sent.
 338   </p></dd>
 339 <dt><span class="term">
 340   hostname
 341   </span></dt>
 342 <dd><p>
 343   the domain name for the query
 344   </p></dd>
 345 </dl></div>
 346 </div>
 347 <div class="sect3" lang="en">
 348 <div class="titlepage"><div><div><h4 class="title">
 349 <a name="id2612775"></a>sample-gai: getaddrinfo() and getnameinfo() test code</h4></div></div></div>
 350 <p>
 351   This is a test program
 352   to check getaddrinfo() and getnameinfo() behavior. It takes a
 353   host name as an argument, calls getaddrinfo() with the given host
 354   name, and calls getnameinfo() with the resulting IP addresses
 355   returned by getaddrinfo(). If the dns.conf file exists and
 356   defines a trust anchor, the underlying resolver will act as a
 357   validating resolver, and getaddrinfo()/getnameinfo() will fail
 358   with an EAI_INSECUREDATA error when DNSSEC validation fails.
 359   </p>
 360 <p>
 361   Usage: sample-gai hostname
 362   </p>
 363 </div>
 364 <div class="sect3" lang="en">
 365 <div class="titlepage"><div><div><h4 class="title">
 366 <a name="id2612790"></a>sample-update: a simple dynamic update client program</h4></div></div></div>
 367 <p>
 368   It accepts a single update command as a
 369   command-line argument, sends an update request message to the
 370   authoritative server, and shows the response from the server. In
 371   other words, this is a simplified <span><strong class="command">nsupdate</strong></span>.
 372   </p>
 373 <p>
 374    Usage: sample-update [options] (add|delete) "update data"
 375   </p>
 376 <p>
 377   Options and Arguments:
 378   </p>
 379 <div class="variablelist"><dl>
 380 <dt><span class="term">
 381   -a auth_server
 382    </span></dt>
 383 <dd><p>
 384         An IP address of the authoritative server that has authority
 385         for the zone containing the update name.  This should normally
 386         be the primary authoritative server that accepts dynamic
 387         updates.  It can also be a secondary server that is configured
 388         to forward update requests to the primary server.
 389    </p></dd>
 390 <dt><span class="term">
 391   -k keyfile
 392    </span></dt>
 393 <dd><p>
 394         A TSIG key file to secure the update transaction.  The keyfile
 395         format is the same as that for the nsupdate utility.
 396    </p></dd>
 397 <dt><span class="term">
 398   -p prerequisite
 399    </span></dt>
 400 <dd><p>
 401         A prerequisite for the update (only one prerequisite can be
 402         specified).  The prerequisite format is the same as that is
 403         accepted by the nsupdate utility.
 404    </p></dd>
 405 <dt><span class="term">
 406   -r recursive_server
 407    </span></dt>
 408 <dd><p>
 409         An IP address of a recursive server that this utility will
 410         use.  A recursive server may be necessary to identify the
 411         authoritative server address to which the update request is
 412         sent.
 413    </p></dd>
 414 <dt><span class="term">
 415   -z zonename
 416    </span></dt>
 417 <dd><p>
 418         The domain name of the zone that contains
 419    </p></dd>
 420 <dt><span class="term">
 421   (add|delete)
 422    </span></dt>
 423 <dd><p>
 424         Specify the type of update operation.  Either "add" or "delete"
 425         must be specified.
 426    </p></dd>
 427 <dt><span class="term">
 428   "update data"
 429    </span></dt>
 430 <dd><p>
 431         Specify the data to be updated.  A typical example of the data
 432         would look like "name TTL RRtype RDATA".
 433   </p></dd>
 434 </dl></div>
 435 <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
 436 <h3 class="title">Note</h3>In practice, either -a or -r must be specified.  Others can
 437    be optional; the underlying library routine tries to identify the
 438    appropriate server and the zone name for the update.</div>
 439 <p>
 440    Examples: assuming the primary authoritative server of the
 441    dynamic.example.com zone has an IPv6 address 2001:db8::1234,
 442    </p>
 443 <pre class="screen">
 444 $ <strong class="userinput"><code>sample-update -a sample-update -k Kxxx.+nnn+mmmm.key add "foo.dynamic.example.com 30 IN A 192.168.2.1"</code></strong></pre>
 445 <p>
 446      adds an A RR for foo.dynamic.example.com using the given key.
 447    </p>
 448 <pre class="screen">
 449 $ <strong class="userinput"><code>sample-update -a sample-update -k Kxxx.+nnn+mmmm.key delete "foo.dynamic.example.com 30 IN A"</code></strong></pre>
 450 <p>
 451      removes all A RRs for foo.dynamic.example.com using the given key.
 452    </p>
 453 <pre class="screen">
 454 $ <strong class="userinput"><code>sample-update -a sample-update -k Kxxx.+nnn+mmmm.key delete "foo.dynamic.example.com"</code></strong></pre>
 455 <p>
 456      removes all RRs for foo.dynamic.example.com using the given key.
 457    </p>
 458 </div>
 459 <div class="sect3" lang="en">
 460 <div class="titlepage"><div><div><h4 class="title">
 461 <a name="id2613536"></a>nsprobe: domain/name server checker in terms of RFC 4074</h4></div></div></div>
 462 <p>
 463   It checks a set
 464   of domains to see the name servers of the domains behave
 465   correctly in terms of RFC 4074. This is included in the set of
 466   sample programs to show how the export library can be used in a
 467   DNS-related application.
 468   </p>
 469 <p>
 470  Usage: nsprobe [-d] [-v [-v...]] [-c cache_address] [input_file]
 471   </p>
 472 <p>
 473    Options
 474   </p>
 475 <div class="variablelist"><dl>
 476 <dt><span class="term">
 477   -d
 478   </span></dt>
 479 <dd><p>
 480         run in the "debug" mode.  with this option nsprobe will dump
 481         every RRs it receives.
 482   </p></dd>
 483 <dt><span class="term">
 484   -v
 485   </span></dt>
 486 <dd><p>
 487         increase verbosity of other normal log messages.  This can be
 488         specified multiple times
 489   </p></dd>
 490 <dt><span class="term">
 491   -c cache_address
 492   </span></dt>
 493 <dd><p>
 494         specify an IP address of a recursive (caching) name server.
 495         nsprobe uses this server to get the NS RRset of each domain and
 496         the A and/or AAAA RRsets for the name servers.  The default
 497         value is 127.0.0.1.
 498   </p></dd>
 499 <dt><span class="term">
 500   input_file
 501   </span></dt>
 502 <dd><p>
 503         a file name containing a list of domain (zone) names to be
 504         probed.  when omitted the standard input will be used.  Each
 505         line of the input file specifies a single domain name such as
 506         "example.com".  In general this domain name must be the apex
 507         name of some DNS zone (unlike normal "host names" such as
 508         "www.example.com").  nsprobe first identifies the NS RRsets for
 509         the given domain name, and sends A and AAAA queries to these
 510         servers for some "widely used" names under the zone;
 511         specifically, adding "www" and "ftp" to the zone name.
 512   </p></dd>
 513 </dl></div>
 514 </div>
 515 </div>
 516 <div class="sect2" lang="en">
 517 <div class="titlepage"><div><div><h3 class="title">
 518 <a name="id2613600"></a>Library References</h3></div></div></div>
 519 <p>As of this writing, there is no formal "manual" of the
 520   libraries, except this document, header files (some of them
 521   provide pretty detailed explanations), and sample application
 522   programs.</p>
 523 </div>
 524 </div>
 525 </div>
 526 <div class="navfooter">
 527 <hr>
 528 <table width="100%" summary="Navigation footer">
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 534 </td>
 535 </tr>
 536 <tr>
 537 <td width="40%" align="left" valign="top">Appendix C. General <acronym class="acronym">DNS</acronym> Reference Information </td>
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