socket-recvfrom.xml

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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.socket-recvfrom">
 <refnamediv>
  <refname>socket_recvfrom</refname>
  <refpurpose>Receives data from a socket whether or not it is connection-oriented</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>socket_recvfrom</methodname>
   <methodparam><type>resource</type><parameter>socket</parameter></methodparam>
   <methodparam><type>string</type><parameter role="reference">buf</parameter></methodparam>
   <methodparam><type>int</type><parameter>len</parameter></methodparam>
   <methodparam><type>int</type><parameter>flags</parameter></methodparam>
   <methodparam><type>string</type><parameter role="reference">name</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter role="reference">port</parameter></methodparam>
  </methodsynopsis>
  <para>
   The <function>socket_recvfrom</function> function receives
   <parameter>len</parameter> bytes of data in <parameter>buf</parameter> from
   <parameter>name</parameter> on port <parameter>port</parameter> (if the
   socket is not of type <constant>AF_UNIX</constant>) using
   <parameter>socket</parameter>. <function>socket_recvfrom</function> can be
   used to gather data from both connected and unconnected sockets.
   Additionally, one or more flags can be specified to modify the behaviour of
   the function.
  </para>
  <para>
   The <parameter>name</parameter> and <parameter>port</parameter> must be
   passed by reference. If the socket is not connection-oriented,
   <parameter>name</parameter> will be set to the internet protocol address of
   the remote host or the path to the UNIX socket. If the socket is
   connection-oriented, <parameter>name</parameter> is &null;. Additionally,
   the <parameter>port</parameter> will contain the port of the remote host in
   the case of an unconnected <constant>AF_INET</constant> or
   <constant>AF_INET6</constant> socket. 
  </para>
  &note.bin-safe;
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>socket</parameter></term>
     <listitem>
      <para>
       The <parameter>socket</parameter> must be a socket resource previously
       created by socket_create().
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>buf</parameter></term>
     <listitem>
      <para>
       The data received will be fetched to the variable specified with
       <parameter>buf</parameter>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>len</parameter></term>
     <listitem>
      <para>
       Up to <parameter>len</parameter> bytes will be fetched from remote host.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>flags</parameter></term>
     <listitem>
      <para>
       The value of <parameter>flags</parameter> can be any combination of 
       the following flags, joined with the binary OR (<literal>|</literal>)
       operator.
      </para>
      
      <table>
       <title>Possible values for <parameter>flags</parameter></title>
       <tgroup cols="2">
        <thead>
         <row>
          <entry>Flag</entry>
          <entry>Description</entry>
         </row>
        </thead>
        <tbody>
         <row>
          <entry><constant>MSG_OOB</constant></entry>
          <entry>
           Process out-of-band data.
          </entry>
         </row>
         <row>
          <entry><constant>MSG_PEEK</constant></entry>
          <entry>
           Receive data from the beginning of the receive queue without
           removing it from the queue.
          </entry>
         </row>
         <row>
          <entry><constant>MSG_WAITALL</constant></entry>
          <entry>
           Block until at least <parameter>len</parameter> are received.
           However, if a signal is caught or the remote host disconnects, the
           function may return less data.
          </entry>
         </row>
         <row>
          <entry><constant>MSG_DONTWAIT</constant></entry>
          <entry>
           With this flag set, the function returns even if it would normally
           have blocked.
          </entry>
         </row>
        </tbody>
       </tgroup>
      </table>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>name</parameter></term>
     <listitem>
      <para>
       If the socket is of the type <constant>AF_UNIX</constant> type,
       <parameter>name</parameter> is the path to the file. Else, for
       unconnected sockets, <parameter>name</parameter> is the IP address of,
       the remote host, or &null; if the socket is connection-oriented.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>port</parameter></term>
     <listitem>
      <para>
       This argument only applies to <constant>AF_INET</constant> and
       <constant>AF_INET6</constant> sockets, and specifies the remote port
       from which the data is received. If the socket is connection-oriented,
       <parameter>port</parameter> will be &null;.
      </para>
     </listitem>
    </varlistentry>
    
   </variablelist>
  </para>
 </refsect1>
 
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   <function>socket_recvfrom</function> returns the number of bytes received,
   or &false; if there was an error. The actual error code can be retrieved by 
   calling <function>socket_last_error</function>. This error code may be
   passed to <function>socket_strerror</function> to get a textual explanation
   of the error.
  </para>
 </refsect1>
                     
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>socket_recvfrom</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
error_reporting(E_ALL | E_STRICT);

$socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
socket_bind($socket, '127.0.0.1', 1223);

$from = '';
$port = 0;
socket_recvfrom($socket, $buf, 12, 0, $from, $port);

echo "Received $buf from remote address $from and remote port $port" . PHP_EOL;
?>
]]>
    </programlisting>
    <para>
     This example will initiate a UDP socket on port 1223 of 127.0.0.1
     and print at most 12 characters received from a remote host.
    </para>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>socket_recv</function></member>
    <member><function>socket_send</function></member>
    <member><function>socket_sendto</function></member>
    <member><function>socket_create</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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