lwres_getnameinfo.docbook

非常好的dns解析软件

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<refentry>

  <refentryinfo>
    <date>Jun 30, 2000</date>
  </refentryinfo>

  <refmeta>
    <refentrytitle>lwres_getnameinfo</refentrytitle>
    <manvolnum>3</manvolnum>
    <refmiscinfo>BIND9</refmiscinfo>
  </refmeta>

  <docinfo>
    <copyright>
      <year>2004</year>
      <year>2005</year>
      <year>2007</year>
      <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
    </copyright>
    <copyright>
      <year>2000</year>
      <year>2001</year>
      <holder>Internet Software Consortium.</holder>
    </copyright>
  </docinfo>

  <refnamediv>
    <refname>lwres_getnameinfo</refname>
    <refpurpose>lightweight resolver socket address structure to hostname and
      service name
    </refpurpose>
  </refnamediv>
  <refsynopsisdiv>
    <funcsynopsis>
<funcsynopsisinfo>#include &lt;lwres/netdb.h&gt;</funcsynopsisinfo>
<funcprototype>
        <funcdef>
int
<function>lwres_getnameinfo</function></funcdef>
        <paramdef>const struct sockaddr *<parameter>sa</parameter></paramdef>
        <paramdef>size_t <parameter>salen</parameter></paramdef>
        <paramdef>char *<parameter>host</parameter></paramdef>
        <paramdef>size_t <parameter>hostlen</parameter></paramdef>
        <paramdef>char *<parameter>serv</parameter></paramdef>
        <paramdef>size_t <parameter>servlen</parameter></paramdef>
        <paramdef>int <parameter>flags</parameter></paramdef>
      </funcprototype>
</funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>DESCRIPTION</title>

    <para>
       This function is equivalent to the
      <citerefentry>
        <refentrytitle>getnameinfo</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry> function defined in RFC2133.
      <function>lwres_getnameinfo()</function> returns the
      hostname for the
      <type>struct sockaddr</type> <parameter>sa</parameter> which
      is
      <parameter>salen</parameter> bytes long.  The hostname is of
      length
      <parameter>hostlen</parameter> and is returned via
      <parameter>*host.</parameter> The maximum length of the
      hostname is
      1025 bytes: <constant>NI_MAXHOST</constant>.
    </para>

    <para> The name of the service associated with the port number in
      <parameter>sa</parameter> is returned in <parameter>*serv.</parameter>
      It is <parameter>servlen</parameter> bytes long.  The
      maximum length
      of the service name is <constant>NI_MAXSERV</constant> - 32
      bytes.
    </para>

    <para>
       The <parameter>flags</parameter> argument sets the
      following
      bits:
      <variablelist>
        <varlistentry>
          <term><constant>NI_NOFQDN</constant></term>
          <listitem>
            <para>
              A fully qualified domain name is not required for local hosts.
              The local part of the fully qualified domain name is returned
              instead.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><constant>NI_NUMERICHOST</constant></term>
          <listitem>
            <para>
              Return the address in numeric form, as if calling inet_ntop(),
              instead of a host name.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><constant>NI_NAMEREQD</constant></term>
          <listitem>
            <para>
              A name is required. If the hostname cannot be found in the DNS
              and
              this flag is set, a non-zero error code is returned.
              If the hostname is not found and the flag is not set, the
              address is returned in numeric form.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><constant>NI_NUMERICSERV</constant></term>
          <listitem>
            <para>
              The service name is returned as a digit string representing the
              port number.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><constant>NI_DGRAM</constant></term>
          <listitem>
            <para>
              Specifies that the service being looked up is a datagram
              service,  and causes getservbyport() to be called with a second
              argument of "udp" instead of its default of "tcp".  This is
              required
              for the few ports (512-514) that have different services for UDP
              and
              TCP.
            </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </para>
  </refsect1>

  <refsect1>
    <title>RETURN VALUES</title>
    <para><function>lwres_getnameinfo()</function>
      returns 0 on success or a non-zero error code if an error occurs.
    </para>
  </refsect1>
  <refsect1>
    <title>SEE ALSO</title>
    <para><citerefentry>
        <refentrytitle>RFC2133</refentrytitle>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>getservbyport</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>lwres</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>lwres_getnameinfo</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>lwres_getnamebyaddr</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>.
      <citerefentry>
        <refentrytitle>lwres_net_ntop</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>.
    </para>
  </refsect1>
  <refsect1>
    <title>BUGS</title>
    <para>
      RFC2133 fails to define what the nonzero return values of
      <citerefentry>
        <refentrytitle>getnameinfo</refentrytitle><manvolnum>3</manvolnum>
      </citerefentry>
      are.
    </para>
  </refsect1>
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