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(PHP 4 >= 4.1.0, PHP 5)
socket_read — Reads a maximum of length bytes from a socket
$socket
, int $length
[, int $type
= PHP_BINARY_READ
] )
The function socket_read() reads from the socket
resource socket
created by the
socket_create() or
socket_accept() functions.
socket
A valid socket resource created with socket_create() or socket_accept() .
length
The maximum number of bytes read is specified by the
length
parameter. Otherwise you can use
\r
, \n
,
or \0
to end reading (depending on the type
parameter, see below).
type
Optional type
parameter is a named constant:
PHP_BINARY_READ
(Default) - use the system
recv() function. Safe for reading binary data.
PHP_NORMAL_READ
- reading stops at
\n or \r.
socket_read() returns the data as a string on success,
or FALSE
on error (including if the remote host has closed the
connection). The error code can be retrieved with
socket_last_error() . This code may be passed to
socket_strerror() to get a textual representation of
the error.
Note:
socket_read() returns a zero length string ("") when there is no more data to read.
[#1] dhaubert dot ti at gmail dot com [2015-08-28 15:16:42]
A way to wait for a message response by the socket or take the first message incoming.
Note that if the server turn offline, you have a socket resource, but while trying socket_read(), it gives you a warning message that will fill your hard drive kickly due to logging.
The example above try read the message at best 3 times, 3 seconds sleeping for another reading.
<?php
function waitResponse($response = "") {
$status = "";
$tries = 3;
$counter = 0;
while ($status == $response) {
$status = socket_read($socket, 1024);
if(!$status){
if($counter >= $tries){
break;
}else{
$counter++;
sleep(3);
}
}
}
return $response;
}
[#2] cottton at i-stats dot net [2014-10-12 21:39:28]
quote:
"Note:
socket_read() returns a zero length string ("") when there is no more data to read."
This is not true!
In a while loop
(example case few bytes to receive - just enough for 1 call, but you use a loop to be sure you received all data)
if you use
<?php socket_set_block($socket); ?>
you will get:
1st call in loop: data
2nd call in loop: a block forever, if there isnt data anymore or w/e happen to the "other side"
So ofc you want to use
<?php socket_set_nonblock($socket); ?>
and you will get:
1st call in loop: data
2nd call in loop: socket_read() returns FALSE (bool) and socket_last_error() gives you a SOCKET_EWOULDBLOCK (http://de1.php.net/manual/de/sockets.constants.php)
There is not a single time i got a empty string back from socket_read.
And im "working" on this problem(bug?) since a week or so.
You better use socket_recv() instead.
(good luck)
[#3] eng.mrkto.com [2011-03-29 04:42:24]
It seems like in socket_* functions in BLOCKING mode where is no way to check if more than $length bytes are still available in socket (like stream_get_meta_data()['unread_bytes']).
So you need to choose your prefered maximum $length (like 133693415:) or use non-blocking mode (for realy big data reciving).
[#4] t33th4n at gmail dot com [2009-02-23 12:53:24]
I don't know if is it stated anywhere with this clearance, but here is the source code for detecting the connection abort/closure for sockets testing with socket_read function:
<?php
$buf = @socket_read($routes[$i][$connectionid]['tunnelsrc'], $buffer_size);
if ($buf === '')
{
$routes[$i][$connectionid]['disconnected']='Conenction abort at source side';
}
?>
($buf === '') is the key :)
I was making an ecrypted tunnel script with mcrypt and was annoying that i could not detect the connection abort from any side.
[#5] tech [{at}] swatcash [{dot}] com [2008-07-01 16:23:35]
Messed up the end of my previous one. Corrected version here:
a simple work around to non-blocking working with normal read is like so:
$read = array($socket);
$write = NULL;
$except = NULL;
while(1) {
$num_changed_sockets = socket_select($read, $write, $except, 0, 1);
if ( $num_changed_sockets > '0' ) {
socket_read($socket,10000,PHP_NORMAL_READ);
}
}
[#6] Anonymous [2007-12-15 11:11:16]
On non-blocking connections it may not return full length requested.
[#7] nad0r1 at hush dot ai [2007-11-20 07:59:03]
Another way to bypass the annoying thing with telnet, that send each character as a string ,is to check if the response is "\r\n", that is the string that telnet sends when the user presses enter.
Here is an example:
<?php
error_reporting(E_ALL);
set_time_limit(0);
ob_implicit_flush();
$address = '127.0.0.1';
$port = 100;
if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) {
echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";
}
if (socket_bind($sock, $address, $port) === false) {
echo "socket_bind() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
}
else
echo 'Socket ' . $address . ':' . $port . " has been opened\n";
if (socket_listen($sock, 5) === false) {
echo "socket_listen() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
}
else
echo "Listening for new clients..\n";
$client_id = 0;
do {
if (($msgsock = socket_accept($sock)) === false) {
echo "socket_accept() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
break;
}
else {
$client_id += 1;
echo "Client #" .$client_id .": Connect\n";
}
$msg = "\nWelcome to the PHP Test Server. \n" .
"To quit, type 'quit'. To shut down the server type 'shutdown'.\n";
socket_write($msgsock, $msg, strlen($msg));
$cur_buf = '';
do {
if (false === ($buf = socket_read($msgsock, 2048))) {
echo "socket_read() failed: reason: " . socket_strerror(socket_last_error($msgsock)) . "\n";
break 2;
}
if ($buf == "\r\n") {
if ($cur_buf == 'quit') {
echo 'Client #' .$client_id .': Disconnect' . "\n";
break;
}
if ($cur_buf == 'shutdown') {
socket_close($msgsock);
break 2;
}
//else {
$talkback = "Unknown command: " . str_replace("\r\n", '\r\n', $cur_buf) ."\n";
socket_write($msgsock, $talkback, strlen($talkback));
// }
echo 'Client #' .$client_id .': ' . $cur_buf . "\n";
$cur_buf = '';
}
else $cur_buf .= $buf;
} while (true);
socket_close($msgsock);
} while (true);
socket_close($sock);
?>
[#8] jgbustos at gmail dot com [2007-07-17 05:47:10]
PHP on win32 developers, please look at this bug report before using the PHP_NORMAL_READ option:
http://bugs.php.net/bug.php?id=21197
In a nutshell, using PHP_NORMAL_READ will make your calls to socket_read() return an empty buffer every time.
[#9] ein at anti-logic dot com [2007-06-28 11:32:58]
the proper way to detect a closed connection is to check socket_last_error.
Connection reset by peer is 104 (either use socket_strerror or don't suppress errors for the time being to find these out), sooo.
while($buffer=@socket_read($sock,512,PHP_NORMAL_READ)){
echo $buffer;
}
if(socket_last_error($sock) == 104) {
echo "Connection closed";
}
[#10] nuitari-php at nuitari dot net [2007-06-13 23:08:35]
PHP_NORMAL_READ - reading stops at \n or \r.
This seems to be meant literally.
If there is a \r, then it will stop reading, even if there is a \n right after it. You have to call the read again just to get rid of the \n.
[#11] dotpointer [2007-02-04 15:27:47]
PHP 5.2.0 / Win32 / Apache 1.3 - It seems like...
PHP_BINARY_READ - works, but returns '', not FALSE...
- is blocking, until data received or connection closed
- does pass-through \r\n etc.
- returns data on data, '' on connection closed
- you can detect closed connection by checking for '' (not FALSE as stated i manual)
PHP_NORMAL_READ - not working so good...
- is non-blocking
- does not pass-through \r\n etc.
- returns false on no-data, false on connection closed :(
- (no way here to detect a closed connection...?)
- (is this a bug? http://bugs.php.net/bug.php?id=21880 )
- (is this a bug? http://bugs.php.net/bug.php?id=21197 )
- (could not get data from this option at all in fact...)
PHP_BINARY_READ seems to be the "right way to go"
for now. Both checking for '' and false to detect closed
connection is probably smart, as this "bug"(?) may
be fixed...
[#12] Niels laukens [2006-08-21 00:34:22]
This paragraph is confusing:
socket_read() returns the data as a string on success, or FALSE on error (including if the remote host has closed the connection). The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual representation of the error.
Note: socket_read() returns a zero length string ("") when there is no more data to read.
My tests (on PHP 5.1.4) show that when you socket_read() on a shutdown-socket, it returns FALSE when using PHP_NORMAL_READ, but returns "" when reading in PHP_BINARY_READ.
[#13] Bill Kuker [2005-03-18 07:31:51]
Just a note that on my system the length seems to have an undocumented upper bound of 65536. I was being lazy and not read()ing in a while loop until I pointed it at real data ;)
[#14] michi at tr51 dot org [2004-05-26 12:48:34]
if you'd like to make a "socket_read" on a linux-system connected with a flash-client (v. 6.0 r81) you have to send a string to the connected port:
<?php
... //initialising communication
$string = "ready to get/send data\0";
socket_write($socket, $string);
//now you can read from...
$line = trim(socket_read($socket, MAXLINE));
... // do some stuff, finaly close connection
?>
[#15] magicking89 at hotmail dot com [2003-08-30 16:01:17]
if you want to use a non block socket you must to use socket_last_error
if(!socket_last_error($sc)){
if($buffer=socket_read($sc,512,PHP_NORMAL_READ)){
echo $buffer;
}
}
if you use it your script wont take all your memory
[#16] schst at php-tools dot de [2003-07-04 18:19:26]
You may download a generic server class at http://www.php-tools.de
This class will accept the sockets read data from it and hands it to a callback function. Furthermore there are methods for connection handling included.
[#17] [2002-09-24 11:48:47]
Windows telnet sends/recieves one character at a time. Try adding PHP_NORMAL_READ to the end of socket_read, that might help.