socket_read

(PHP 4 >= 4.1.0, PHP 5)

socket_read — Reads a maximum of length bytes from a socket

说明

string socket_read ( resource $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.

参数

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.

返回值

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.

参见

socket_accept() - Accepts a connection on a socket
socket_bind() - 给套接字绑定名字
socket_connect() - 开启一个套接字连接
socket_listen() - Listens for a connection on a socket
socket_last_error() - Returns the last error on the socket
socket_strerror() - Return a string describing a socket error
socket_write() - Write to a socket

用户评论:

[#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.