Edit report at http://bugs.php.net/bug.php?id=52848&edit=1
ID: 52848
Updated by: cataphr...@php.net
Reported by: php dot net at phrozenbyte dot de
Summary: Processing out-of-band data doesn't work
Status: To be documented
Type: Bug
Package: Streams related
Operating System: Ubuntu 10.04 Lucid Lynx
PHP Version: 5.3.3
Block user comment: N
New Comment:
I can't reproduce this on Debian Lenny:
0: init
0: select
16: $read contains: array(1) {
[0]=>
resource(2) of type (stream)
}
16: $except contains: array(0) {
}
16: client connected
16: select
16: $read contains: array(0) {
}
16: $except contains: array(1) {
[0]=>
resource(3) of type (stream)
}
16: oob-data: 'a'
16: select
26: $read contains: array(1) {
[0]=>
resource(3) of type (stream)
}
26: $except contains: array(0) {
}
26: client disconnected
Previous Comments:
------------------------------------------------------------------------
[2010-09-16 19:24:42] php dot net at phrozenbyte dot de
I keeped the server script and replaced the client script with yours.
The result:
number of $read sockets: 1
number of $except sockets: 1
There's definitly a issue... Keep the client and try the following
server script:
<?php
$now = time();
$server = stream_socket_server('tcp://127.0.0.1:1234');
echo time()-$now.": init\n";
do {
$read = $write = $except = array();
$read[] = $server;
if(isset($client)) {
$read[] = $client;
$except[] = $client;
}
echo time()-$now.": select\n";
stream_select($read, $write, $except, null);
echo time()-$now.': $read contains: '; var_dump($read);
echo time()-$now.': $except contains: '; var_dump($except);
foreach($except as $sock) { // $sock === $client
echo time()-$now.": oob-data:
'".stream_socket_recvfrom($client, 1500,
STREAM_OOB)."'\n";
}
foreach($read as $sock) {
if($sock === $server) {
$client = stream_socket_accept($server);
echo time()-$now.": client connected\n";
} else { // $sock === $client
if(feof($client)) {
echo time()-$now.": client disconnected\n";
break 2;
}
$data = stream_socket_recvfrom($client, 1500);
echo time()-$now.": data: '".$data."'\n";
}
}
} while(true);
?>
The script returns the following (notice the time!):
0: init
0: select
0: $read contains: array(1) {
[0]=>
resource(5) of type (stream)
}
0: $except contains: array(0) {
}
0: client connected
0: select
0: $read contains: array(1) {
[0]=>
resource(6) of type (stream)
}
0: $except contains: array(1) {
[0]=>
resource(6) of type (stream)
}
0: oob-data: 'a'
10: client disconnected
That's wrong! At the second call of stream_select() the $read array
shouldn't contain any socket, only the $except array does because
there's data to read. The time delay between "0: oob-data: 'a'" and "10:
client disconnected" is a result of recv()s blocking. stream_select()
shouldn't fill $read when there's no data to read. The client-side
disconnect affects nothing, that happens (as you can see) 10 seconds
later.
------------------------------------------------------------------------
[2010-09-16 12:40:35] cataphr...@php.net
There's still no bug. Here's a portion of the strace on the server:
socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 3
setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
bind(3, {sa_family=AF_INET, sin_port=htons(1234),
sin_addr=inet_addr("127.0.0.1")}, 16) = 0
listen(3, 32) = 0
poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 25000) = 1 ([{fd=3,
revents=POLLIN}])
accept(3, {sa_family=AF_INET, sin_port=htons(42533),
sin_addr=inet_addr("127.0.0.1")}, [16]) = 4
select(5, [3 4], [], [4], NULL) = 2 (in [4]], except [4])
So you call see that the call to select() actually returned the socket
handle in both fd_set structures, as PHP reported.
The reason for returning the socket handle in readfs is that the
connection was closed on the client side. If you don't close the
connection, you get your expected result.
Keep the same code on the server and use this for the client:
<?php
$socket = stream_socket_client('tcp://127.0.0.1:1234');
stream_socket_sendto($socket, 'a', STREAM_OOB);
sleep(10);
fclose($socket);
You now see:
number of $read sockets: 0
number of $except sockets: 1
------------------------------------------------------------------------
[2010-09-16 04:43:44] php dot net at phrozenbyte dot de
Yes, I understand that.
The issue is in a more special case: When the client sends a single byte
(!) with OOB flag, the server will receive 2 recv calls - the first one
including the single byte with OOB flag and the second one is empty
which results in feof() = true.
That means: Even when you send only a single byte with OOB flag, in
which case you can't read non-OOB-data, stream_select() triggers that
you can read non-OOB-data. And this is a issue with php I think.
Client:
---------------
<?php
$socket = stream_socket_client('tcp://127.0.0.1:1234');
stream_socket_sendto($socket, 'a', STREAM_OOB);
fclose($socket);
?>
Server:
---------------
<?php
$server = stream_socket_server('tcp://127.0.0.1:1234');
$socket = stream_socket_accept($server);
$read = array($server, $socket); $write = array(); $except =
array($socket);
stream_select($read, $write, $except, null);
echo 'number of $read sockets: '.count($read)."\n";
echo 'number of $except sockets: '.count($except)."\n";
?>
Expected result:
---------------
number of $read sockets: 0
number of $except sockets: 1
Actual result:
---------------
number of $read sockets: 1
number of $except sockets: 1
------------------------------------------------------------------------
[2010-09-16 02:06:58] srina...@php.net
few additional comments
on Linux/Solaris socket implementations, when you send with MSG_OOB
flags set, only the last byte is recvd. the subsequent recv call will
flush out the rest of the bytes.
for example, in your example,if you edit it like below you will notice
this more clearly:
client script
<?php
$socket = stream_socket_client('tcp://127.0.0.1:1234');
stream_socket_sendto($socket, '123456789', STREAM_OOB);
fclose($socket);
?>
server (with 2 recv calls even though client is sending only one send
call.)
<?php
$server = stream_socket_server('tcp://127.0.0.1:1234');
stream_set_timeout($server, 180);
$socket = stream_socket_accept($server);
echo "Data: '".stream_socket_recvfrom($socket, 100, STREAM_OOB)."'\n";
echo "Data: '".stream_socket_recvfrom($socket, 100)."'\n";
?>
Hope this clarifies
I don't think this is an issue with PHP.
------------------------------------------------------------------------
[2010-09-15 22:17:16] php dot net at phrozenbyte dot de
When you're sending data out-of-band (one or more bytes make no
difference) and the client socket is in $read and $except of
stream_select() the socket will be available every time in both arrays.
------------------------------------------------------------------------
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
http://bugs.php.net/bug.php?id=52848
--
Edit this bug report at http://bugs.php.net/bug.php?id=52848&edit=1
