I try show output from socket but the return is showed cut.
<?php
$socket = '/var/run/qemu-server/121.serial1';
$sock = stream_socket_client('unix://'.$socket, $errno, $errstr);
fwrite($sock, $argv[1] . "\r\n");
$data = '';
while ($buffer = fread($sock, 8128)) $data .= $buffer;
echo $data;
fclose($sock);
?>
I need this output:
{"VMid":"121","Command":"ls /","Output":"bin\nboot\ndev\netc\nhome\nlib\nlib32\nlib64\nlibx32\nlost+found\nmedia\nmnt\nopt\nproc\nroot\nrun\nsbin\nsnap\nsrv\nswap.img\nsys\ntmp\nusr\nvar\n"}
But it only returns:
{"VMid":"121","Command":"ls /","Output"
I tried "stream_set_read_buffer", "file_get_contents" and no success.
I presume here that the server has not had time to fully respond by the time you are polling. You can quickly test this theory by putting a sleep() after you send the instruction (fwrite) before you poll (fread). That's a test solution, not final (as you never know how long to "sleep" for).
What you need for sockets generally are a continuous poll (while loop that basically never ends, but under control so you can pause / exit etc), and continuous buffer read/write (append new content to a buffer; when you either reach the end of expected message OR you read the number of bytes you expect* remove that content from the front of the buffer and leave the remainder for next loop. You can, of course, bomb out at this point if you have everything you need and close the socket or return to polling later.
A common trick is to set the first two/four bytes of the message to the length of the payload, then the payload. So you constantly would poll for those two/four bytes and then read the content based of that. Probably not possible with another system like QEMU, so you'll need to look instead for...? EOL/NL etc?
Related
I'm using SSH2 to establish a stream into a device running modified linux. After the stream is established, I set blocking to true and begin reading the output. Once I see the word "Last", I know that the system is ready to accept commands, so I send one. I then read the output generated by that command.
This all works perfectly, except, I have to manually close the stream. I'm pretty sure that I'm not getting an EOF or newline back and this is probably why, however, this is all new to me so I could be wrong.
Looking to exit once the output is done.
Here is what I'm looking for before I send the first command:
Last login: Tue May 7 06:41:55 PDT 2013 from 10.150.102.115
The loop that echos the output. I have to check for the word "Last" - I ignore if it its seen more than once. (It was causing the loop to repeat.):
// Prevents premature termination
$lastCount = 1;
stream_set_blocking($stdio, true);
while($line = fgets($stdio)) {
$count++;
flush();
if (strstr($line, 'Last') && $lastCount == 1) {
fwrite($stdio,$command . PHP_EOL);
$lastCount--;
}
echo $line;
}
fclose($stdio);
Your mode is incorrect and should be set to 0.
If mode is 0, the given stream will be switched to non-blocking mode, and if 1, it will be switched to blocking mode. This affects calls like fgets() and fread() that read from the stream. In non-blocking mode an fgets() call will always return right away while in blocking mode it will wait for data to become available on the stream.
http://php.net/manual/en/function.stream-set-blocking.php
Looks like there is a trick to using blocking:
http://www.php.net/manual/en/function.stream-set-blocking.php#110755
Firing a command to socket resource and getting the output takes some decent amount of time in PHP.
I have written code to read the buffered output string after sleep duration of 1 second and it works fine.
If i don't provide any delay after fputs, i don't get any string.
How to determine this time? putting time duration by hit and trial can cause trouble.
For safe side i always put time in seconds.
What parameters affect this time, does anyone has statistical data?
$socket = fsockopen($ip,3083);
$command = 'RTRV-NE-GEN:::123;';
fputs($socket,$command);
sleep(1);
$string = fread( $socket, 3000 );
You probably just need to do fflush($socket); there after you do fputs(...).
I'm using fsockopen to connect to an OpenVAS manager and send XML. The code I am using is:
$connection = fsockopen('ssl://'.$server_data['host'], $server_data['port']);
stream_set_timeout($connection, 5);
fwrite($connection, $xml);
while ($chunk = fread($connection, 2048)) {
$response .= $chunk;
}
However after reading the first two chunks of data, PHP hangs on fread and doesn't time out after 5 seconds. I have tried using stream_get_contents, which gives the same result, BUT if I only use one fread, it works ok, just that I want to read everything, regardless of length.
I am guessing, it is an issue with OpenVAS, which doesn't end the stream the way PHP expects it to, but that's a shot in the dark. How do I read the stream?
I believe that fread is hanging up because on that last chunk, it is expecting 2048 bytes of information and is probably getting less that that, so it waits until it times out.
You could try to refactor your code like this:
$bytes_to_read = 2048;
while ($chunk = fread($connection, $bytes_to_read)) {
$response .= $chunk;
$status = socket_get_status ($connection);
$bytes_to_read = $status["unread_bytes"];
}
That way, you'll read everything in two chunks.... I haven't tested this code, but I remember having a similar issue a while ago and fixing it with something like this.
Hope it helps!
I want to read everything from a textfile and echo it. But there might be more lines written to the text-file while I'm reading so I don't want the script to exit when it has reached the end of the file, instead I wan't it to wait forever for more lines. Is this possible in php?
this is just a guess, but try to pass through (passthru) a "tail -f" output.
but you will need to find a way to flush() your buffer.
IMHO a much nicer solution would be to build a ajax site.
read the contents of the file in to an array. store the number of lines in the session. print the content of the file.
start an ajax request every x seconds to a script which checks the file, if the line count is greater then the session count append the result to the page.
you could use popen() inststed:
$f = popen("tail -f /where/ever/your/file/is 2>&1", 'r');
while(!feof($f)) {
$buffer = fgets($f);
echo "$buffer\n";
flush();
sleep(1);
}
pclose($f)
the sleep is important, without it you will have 100% CPU time.
In fact, when you "echo" it, it goes to the buffer. So what you want is "appending" the new content if it's added while the browser is still receiving output. And this is not possible (but there are some approaches to this).
I solved it.
The trick was to use fopen and when eof is reached move the cursor to the previous position and continue reading from there.
<?php
$handle = fopen('text.txt', 'r');
$lastpos = 0;
while(true){
if (!feof($handle)){
echo fread($handle,8192);
flush();
$lastpos = ftell($handle);
}else{
fseek($handle,$lastpos);
}
}
?>
Still consumes pretty much cpu though, don't know how to solve that.
You may also use filemtime: you get latest modification timestamp, send the output and at the end compare again the stored filemtime with the current one.
Anyway, if you want the script go at the same time that the browser (or client), you should send the output using chunks (fread, flush), then check any changes at the end. If there are any changes, re-open the file and read from the latest position (you can get the position outside of the loop of while(!feof())).
how do i go about reading data being sent almost constantly to my server.
the protocol is udp. if i try to read in a while(1) loop, i dont get anything. it seems like the read will only echo once all the reading is done. so it waits till the loop is done reading which it will never be. i want the socket_read to echo immediately when it gets the data. here is the code that doesnt work. thanks in advance.
<?php
$sock = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
socket_bind($sock, $local, $port) or die('Could not bind to address');
//this is where the reading loop should go.
while(1)
{
echo socket_read($sock,1024);
}
socket_close($sock);
?>
Try calling flush() immediately after that echo statement.
Something like this might help:
do {
echo socket_read($handle,1024);
$status = socket_get_status($handle);
} while($status['unread_bytes']);
OR
while ( $buffer = #socket_read($sock,512,PHP_NORMAL_READ) )
echo $buffer;
The PHP manual entry on socket_read() is a little vague when it comes to how much (if any) internal buffering it's doing. Given that you are passing 1024 in for the length, that specifies that it should return after receiving no more than 1024 bytes of data.
Disclaimer: the following is just speculation, as I have no knowledge of the internal implementation of socket_read().
If the socket_read() function is using its length parameter as a hint for an internal buffer size, you might see bad performance with small UDP packets. For example, if socket_read() waits for 1024 bytes of data regardless of the size of the packets, if you are constantly receiving 60 byte UDP packets it'll take a while for the buffer to fill and the function to return.
(Note: after looking up the "unread_bytes" field mentioned by Tim, it looks like PHP does keep internal buffers, but it makes no mention of how large or small those might be.)
In this case, socket_read() will return larger chunks of data once its buffers fill to reduce processing resource consumption, but at the expense of higher latency. If you need the packets as past as possible, perhaps setting a lower length field would work. That would force socket_read() to return sooner, albeit at the expense of executing your loop more often. Also if you set the length too low, your socket_read()'s might start returning incomplete packets, so you'll have to account for that in your code. (If that matters for your application, of course.)
I needed to call ob_flush();. Never even heard of it before. turns out my problem wasn't the loop, but the fact that php naturally waits till script is done before actually sending the internal buffer to the web browser. calling flush(); followed by ob_flush(); will force php to send whatever buffer it has stored to the browser immediately. This is needed for scripts that will not stop (infinite loops) and want to echo data to the browser. Sometimes flush() doesn't work as it didn't in this case. Hope that helps.