socket-recv.xml

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<refentry xml:id="function.socket-recv" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>socket_recv</refname>
  <refpurpose>Receives data from a connected socket</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>int</type><type>false</type></type><methodname>socket_recv</methodname>
   <methodparam><type>Socket</type><parameter>socket</parameter></methodparam>
   <methodparam><type class="union"><type>string</type><type>null</type></type><parameter role="reference">data</parameter></methodparam>
   <methodparam><type>int</type><parameter>length</parameter></methodparam>
   <methodparam><type>int</type><parameter>flags</parameter></methodparam>
  </methodsynopsis>
  <para>
   The <function>socket_recv</function> function receives
   <parameter>length</parameter> bytes of data in <parameter>data</parameter> from
   <parameter>socket</parameter>. <function>socket_recv</function> can
   be used to gather data from connected sockets. Additionally, one or
   more flags can be specified to modify the behaviour of the
   function.
  </para>
  <para>
   <parameter>data</parameter> is passed by reference, so it must be
   specified as a variable in the argument list. Data read from
   <parameter>socket</parameter> by <function>socket_recv</function>
   will be returned in <parameter>data</parameter>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>socket</parameter></term>
     <listitem>
      <para>
       The <parameter>socket</parameter> must be a <classname>Socket</classname> instance previously
       created by <function>socket_create</function>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>data</parameter></term>
     <listitem>
      <para>
       The data received will be fetched to the variable specified with
       <parameter>data</parameter>. If an error occurs, if the
       connection is reset, or if no data is
       available, <parameter>data</parameter> will be set to &null;.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><parameter>length</parameter></term>
     <listitem>
      <para>
       Up to <parameter>length</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>length</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>    
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   <function>socket_recv</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="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     &sockets.changelog.socket-param;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>socket_recv</function> example</title>
    <para>
     This example is a simple rewrite of the first example from
     <xref linkend="sockets.examples"/> to
     use <function>socket_recv</function>.
    </para>
    <programlisting role="php">
<![CDATA[
<?php
error_reporting(E_ALL);

echo "<h2>TCP/IP Connection</h2>\n";

/* Get the port for the WWW service. */
$service_port = getservbyname('www', 'tcp');

/* Get the IP address for the target host. */
$address = gethostbyname('www.example.com');

/* Create a TCP/IP socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
    echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";
} else {
    echo "OK.\n";
}

echo "Attempting to connect to '$address' on port '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) {
    echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "\n";
} else {
    echo "OK.\n";
}

$in = "HEAD / HTTP/1.1\r\n";
$in .= "Host: www.example.com\r\n";
$in .= "Connection: Close\r\n\r\n";
$out = '';

echo "Sending HTTP HEAD request...";
socket_write($socket, $in, strlen($in));
echo "OK.\n";

echo "Reading response:\n\n";
$buf = 'This is my buffer.';
if (false !== ($bytes = socket_recv($socket, $buf, 2048, MSG_WAITALL))) {
    echo "Read $bytes bytes from socket_recv(). Closing socket...";
} else {
    echo "socket_recv() failed; reason: " . socket_strerror(socket_last_error($socket)) . "\n";
}
socket_close($socket);

echo $buf . "\n";
echo "OK.\n\n";
?>
]]>
    </programlisting>
    &example.outputs.similar;
    <screen>
<![CDATA[
<h2>TCP/IP Connection</h2>
OK.
Attempting to connect to '208.77.188.166' on port '80'...OK.
Sending HTTP HEAD request...OK.
Reading response:

Read 123 bytes from socket_recv(). Closing socket...HTTP/1.1 200 OK
Date: Mon, 14 Sep 2009 08:56:36 GMT
Server: Apache/2.2.3 (Red Hat)
Last-Modified: Tue, 15 Nov 2005 13:24:10 GMT
ETag: "b80f4-1b6-80bfd280"
Accept-Ranges: bytes
Content-Length: 438
Connection: close
Content-Type: text/html; charset=UTF-8

OK.
]]>
    </screen>
   </example>
  </para>
 </refsect1>
                     
</refentry>
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