LXIV. Socket functions
The socket extension implements a low-level interface to the
socket communication functions, providing the possibility to act
as a socket server as well as a client.
The socket functions described here are part of an extension to
PHP which must be enabled at compile time by giving the --enable-sockets option to
configure.
For a more generic client-side socket interface, see
fsockopen() and
pfsockopen().
When using these functions, it is important to remember that while
many of them have identical names to their C counterparts, they
often have different declarations. Please be sure to read the
descriptions to avoid confusion.
That said, those unfamiliar with socket programming can still find
a lot of useful material in the appropriate Unix man pages, and
there is a great deal of tutorial information on socket
programming in C on the web, much of which can be applied, with
slight modifications, to socket programming in PHP.
Example 1. Socket example: Simple TCP/IP server
This example shows a simple talkback server. Change the
address and port variables
to suit your setup and execute. You may then connect to the
server with a command similar to: telnet 192.168.1.53
10000 (where the address and port match your
setup). Anything you type will then be output on the server
side, and echoed back to you. To disconnect, enter 'quit'.
<?php
error_reporting (E_ALL);
/* Allow the script to hang around waiting for connections. */
set_time_limit (0);
$address = '192.168.1.53';
$port = 10000;
if (($sock = socket (AF_INET, SOCK_STREAM, 0)) < 0) {
echo "socket() failed: reason: " . strerror ($sock) . "\n";
}
if (($ret = bind ($sock, $address, $port)) < 0) {
echo "bind() failed: reason: " . strerror ($ret) . "\n";
}
if (($ret = listen ($sock, 5)) < 0) {
echo "listen() failed: reason: " . strerror ($ret) . "\n";
}
do {
if (($msgsock = accept_connect($sock)) < 0) {
echo "accept_connect() failed: reason: " . strerror ($msgsock) . "\n";
break;
}
do {
$buf = '';
$ret = read ($msgsock, $buf, 2048);
if ($ret < 0) {
echo "read() failed: reason: " . strerror ($ret) . "\n";
break 2;
}
if ($ret == 0) {
break 2;
}
$buf = trim ($buf);
if ($buf == 'quit') {
close ($msgsock);
break 2;
}
$talkback = "PHP: You said '$buf'.\n";
write ($msgsock, $talkback, strlen ($talkback));
echo "$buf\n";
} while (true);
close ($msgsock);
} while (true);
close ($sock);
?>
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Example 2. Socket example: Simple TCP/IP client
This example shows a simple, one-shot HTTP client. It simply
connects to a page, submits a HEAD request, echoes the reply,
and exits.
<?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.php.net');
/* Create a TCP/IP socket. */
$socket = socket (AF_INET, SOCK_STREAM, 0);
if ($socket < 0) {
echo "socket() failed: reason: " . strerror ($socket) . "\n";
} else {
"socket() successful: " . strerror ($socket) . "\n";
}
echo "Attempting to connect to '$address' on port '$service_port'...";
$result = connect ($socket, $address, $service_port);
if ($result < 0) {
echo "connect() failed.\nReason: ($result) " . strerror($result) . "\n";
} else {
echo "OK.\n";
}
$in = "HEAD / HTTP/1.0\r\n\r\n";
$out = '';
echo "Sending HTTP HEAD request...";
write ($socket, $in, strlen ($in));
echo "OK.\n";
echo "Reading response:\n\n";
while (read ($socket, $out, 2048)) {
echo $out;
}
echo "Closing socket...";
close ($socket);
echo "OK.\n\n";
?>
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- Table of Contents
- accept_connect — Accepts a connection on a socket
- bind — Binds a name to a socket
- close — Closes a file descriptor
- connect — Initiates a connection on a socket
- listen — Listens for a connection on a socket
- socket — Create a socket (endpoint for communication)
- strerror — Return a string describing a socket error