socket_read
It looks like that mysterious flags are just the recv(2) flags passed to your OS syscall and nothing more...
ext/sockets/sockets.c:PHP_FUNCTION(socket_recv)
...
if ((retval = recv(php_sock->bsd_socket, recv_buf, len, flags)) < 1) {
efree(recv_buf);
...
for linux you can type `man 2 recv' and you will see complete description of thouse flags.
Sergey S. Kosrtyliov <rathamahata@rathamahata.net>
http://www.rathamahata.net/
socket_recv
(PHP 4 >= 4.1.0, PHP 5)
socket_recv — REcibe información desde un socket conectado
Descripción
int socket_recv
( resource
$socket
, string &$buf
, int $len
, int $flags
)
La función socket_recv() recibe
len bytes de información en buf desde
socket. socket_recv() se puede
usar para reunir información desde sockets conectados. Además, se pueden
especificar una o más banderas para modificar el comportamiento de la
función.
buf es pasado por referencia, por lo que debe ser
especificado como una variable en la lista de argumentos. La información leída desde
socket por socket_recv()
será devuelta en buf.
Parámetros
-
socket -
socketdebe ser un recurso socket previamente creado por socket_create(). -
buf -
La información recibida será traida a la variable especifivada por
buf. Si ocurre un error, si la conexión es reiniciada, o si no hay información disponible,bufserá establecido aNULL. -
len -
Se obtendrán hasta
lenbytes desde el host remoto. -
flags -
El valor de
flagspuede ser una combinación de las siguientes banderas, unidas con el operador binario OR (|).Valores posibles de flagsBandera Descripción MSG_OOBProcesar información fuera de banda. MSG_PEEKRecibir informaicón desde el inicio de la cola recibida sin eliminarla de la cola. MSG_WAITALLBloquea hasta que al menos se reciba lenbytes. Sin embargo, si se captura una señal o el host remoto se desconecta, la función puede devolver menos información.MSG_DONTWAITCon esta bandera establecida, la función devuelve incluso si normalmente habría bloqueado.
Valores devueltos
socket_recv() devuelve el número de bytes recibidos,
o FALSE si hubo un error. El código de error real se puede recuperar
llamando a socket_last_error(). Este código de error se puede
pasar a socket_strerror() para obtener una explicación textual
del error.
Ejemplos
Ejemplo #1 Un ejemplo de socket_recv()
Este ejemplo es un reescrito sencillo del primer ejemplo de Ejemplos para usar socket_recv().
<?php
error_reporting(E_ALL);
echo "<h2>Conexión TCP/IP</h2>\n";
/* Obtener el puerto del servicio WWW. */
$service_port = getservbyname('www', 'tcp');
/* Obtener la dirección IP del host objetivo. */
$address = gethostbyname('www.example.com');
/* Crear un socket TCP/IP. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
echo "socket_create() falló: razón: " . socket_strerror(socket_last_error()) . "\n";
} else {
echo "OK.\n";
}
echo "Intentando conectar a '$address' en el puerto '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) {
echo "socket_connect() falló.\nRazón: ($result) " . socket_strerror(socket_last_error($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";
$out = '';
echo "Enviando petición HTTP HEAD...";
socket_write($socket, $in, strlen($in));
echo "OK.\n";
echo "Leyendo la respuesta:\n\n";
$buf = 'Este es mi buffer.';
if (false !== ($bytes = socket_recv($socket, $buf, 2048, MSG_WAITALL))) {
echo "Leídos $bytes bytes desde socket_recv(). Cerrando el socket...";
} else {
echo "socket_recv() falló; razón: " . socket_strerror(socket_last_error($socket)) . "\n";
}
socket_close($socket);
echo $buf . "\n";
echo "OK.\n\n";
?>
El ejemplo de arriba producirá algo parecido a esto:
<h2>Conexión TCP/IP</h2> OK. Intentando conectar a '208.77.188.166' en el puerto '80'...OK. Enviando petición HTTP HEAD...OK. Leyendo la respuesta: Leídos 123 bytes desde socket_recv(). Cerrando el 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.
add a note
User Contributed Notes
socket_recv - [7 notes]
rathamahata at rathamahata dot net ¶
7 years ago
engine at [NO SPAM] illusiononly dot com ¶
8 years ago
To read from socket both on linux and windows OS having flash as a client I use function bellow. $length is the size of a chunk, not the max length to read. It will continue reading until EOL char occures or client disconnects (or in case of error), so it works for bigger packets as well.
function read($descriptor, $length = 1024) {
$this->method = "read";
if(!$client){
echo("No valid socket descriptor !\n");
return false;
}
$read ='';
while(($flag=socket_recv($descriptor, $buf, $length,0))>0){
$asc=ord(substr($buf, -1));
if ($asc==0) {
$read.=substr($buf,0,-1);
break;
}else{
$read.=$buf;
}
}
if ($flag<0){
//error
return false;
}elseif ($flag==0){
//Client disconnected
return false;
}else{
return $read;
}
}
davide dot renzi at gmail dot com ¶
1 year ago
In PHP version 5.* there is a bug: MSG_DONTWAIT flag is not defined (see https://bugs.php.net/bug.php?id=48326)
Anonymous ¶
8 years ago
My last post was incorrect. The int flag set to 2 apparently reset the file position pointer so what I was reading was the first record repeatedly.
My workaroud ended up being the following:
for($ct=1; $ct<=$numrecs; $ct++) {
$rec = "";
$nr=socket_recv($fp,$rec,76,0);
//grab the extra bytes.
$terminator = "";
while ($terminator != ".") {
$nr=socket_recv($fp,$terminator,1,0);
}
$custarray[]=substr($rec,0,76);
}
Martin K.
Anonymous ¶
8 years ago
I'm glad that Bastion left the above post about the mysterious int flag. He just helped to fix a problem that I've spent six hours on. Here's my code:
for($ct=1; $ct<=$numrecs; $ct++) {
$rec = "";
$nr=socket_recv($fp,$rec,77,0);
print "Rec # $ct -->";
print "$rec";
print "<br>";
}
The code is pretty simple, it just loops through all my records and prints them out. All records are 77 bytes and all end with a period. The first 36 records print perfectly then at 37 things go bad. The records start to get offset. The last few characters of the 37th record end up printing on the 38th record. The data on the sending side was perfect, so I knew that the problem was with socked_recv.
After reading the above post I tried changing the int flag. Changing the flag to 2 worked:
$nr=socket_recv($fp,$rec,77,2);
Now everything lines up perfectly. I had always left int flag as 0 since it's undocumented.
Martin K.
dgk at tcde dot ru ¶
8 years ago
I've used socket_select and socket_recv with a while loop and found myself in trouble when remote side closed connection. The code below produced infinite loop and socket_select returned immediately (which lead to high cpu time consumption).
<?
socket_set_nonblock($my_socket);
$streams = array($my_socket/*, ... */);
$lastAccess = time();
while (socket_select($streams, $write = NULL, $except = NULL, SLEEP_TIME_SECONDS, SLEEP_TIME_MILLISECONDS) !== FALSE) {
if (in_array($my_socket, $streams)) {
while (@socket_recv($my_socket, $data, 8192, 0)) {
echo $data;
}
$lastAccess = time();
} else {
if (time()-$lastAccess > LAST_ACCESS_TIMEOUT) {
break;
}
}
// ...
$streams = array($my_socket/*, ... */);
}
?>
The solution was simple, but quite hard to find because socket_recv is not documented. socket_recv returns FALSE if there is no data and 0 if the socket is widowed (disconnected by remote side). So I had just to check return value of socket_recv. The problem now sounds stupid, but I've spend some time to find it out.
I hope this will save some of somebody's hair ;)
bastiaan at [no-spam] megabass dot nl ¶
9 years ago
in case you want to empty/unset $buffer, but failing to do so, try using 0 as flag.
PHP_NORMAL_READ and PHP_BINARY_READ respectively hold 1 and 2 as value.