Before I start, excuse my english, I'm from Holland :)
I have a question regarding the use of PHP's fsockopen.
My Prerequisites
So basically, I have a Windows program running in the background which has a remote console over TCP/IP that I need to connect to so I can execute a few commands. I am able to connect to that console with KiTTY, and execute my commands without any problems.
My Solution
So the issue I have right now, is that I need to be able to execute these commands from the browser. I have searched the interwebs for best ways to do this and what I found was to use PHP's fsockopen to connect to my console. The code I tried is as follows:
$SOCKET = fsockopen("127.0.0.1", 12101, $errno, $errstr);
if($SOCKET){
echo "Connected!";
}
$firstRead = fread($SOCKET, 8000);
echo($firstRead);
And using fputs to send a command:
fputs($SOCKET, "HELP \r\n");
And after, reading out my response with this:
$response = fread($SOCKET, 8000);
echo $response;
The Problem(s)
But I have encountered a few weird problems when testing this.
As soon as I execute a command like "HELP", I can see from my KiTTY session that the command was executed and that I got a response, but when I read out the response with "fread" I get nothing. But when I use a loop to read it out like this, it reads something from the console at the second try almost everytime:
do {
$response = fread($SOCKET, 8000);
$i++;
} while (strlen($response) < 5 || $i < 5);
( Sometimes, it DOES read something from console on first try, but mostly it only reads something on second try ).
The Question
Now my question(s) is(are), why does it behave so strangely? And is it because I am doing something wrong? And is this really the best way to do this?
sidenote
When this works, I need to be able to call these PHP functions ( or something similar ) with a bunch of AJAX requests and get the response to show in the browser. This is an absolute MUST so please keep this in mind when writing a possible answer :)
Thanks everyone!
When you create a socket with fsockopen in PHP you might also want to specify if it is blocking or non-blocking, in case of a non-blocking socket the function socket_read will return false on error or if the connection was closed, or empty string until some data is received, in case of a blocking socket instead when you read on it, it will block until there is some data to read (or empty string if a timeout is hit).
The behavior you described seems to be non-blocking.
For changing the blocking type there are: socket_set_block and socket_set_nonblock.
When your code with sockets works, there won't be any problems with AJAX requests, but keep in mind to set a timeout in PHP socket, otherwise if the server is down or simply too slow the request will fail with error (a timeout from php if set_time_limit is exceeded, which is a fatal error, or a JavaScript one with the browser timeout constant).
Here are the links to manual of socket_read and socket_write, which I think are more appropriated of fread and fputs.
I am using phpseclib and I am trying to login using an RSA key:
$ssh = new SSH2('<server_domain_name>');
$key = new RSA();
$key->load(file_get_contents('<private_key_path>'));
if($ssh->login('root',$key)){
echo "Logged In!!!";
} else {
echo "Login failed!";
}
but login fails! Looking inside the SSH2 class I can see that logging in with RSA key takes place in the _login_helper() function (correct if I am wrong) which is called by the _login() function which is called by the login() function (under circumstances).
login() -> _login() -> _login_helper()
But this piece of code:
if (!($this->bitmap & self::MASK_CONSTRUCTOR)) {
if (!$this->_connect()) {
return false;
}
}
in the _login() function always returns false and by so the execution never reaches the _login_helper() function. The reason for the above part of code returning false is the default values of these variables/constants:
var $bitmap = 0;
const MASK_CONNECTED = 0x00000002;
I am little bit frustrated. Am I missing something?
EDIT: I forgot to mention that login returns/fails after a few seconds. Adding a few ECHOs in the _connect() method I can see that the method times out while waiting for server data. During the execution of this loop:
while (!feof($this->fsock) && !preg_match('#(.*)^(SSH-(\d\.\d+).*)#ms', $data, $matches))
the server outputs just one line saying "SSH-2.0-OpenSSH_4.3" and then (the second time the loop executes) it times out here:
if (!#stream_select($read, $write, $except, $sec, $usec) && !count($read)) {
EDIT 2: The SSH logs of the side that I am trying to connect to say:
Connection closed by THE_SSH_SERVER_IP
Nov 4 23:09:58 web1 sshd[10316]: Did not receive identification string fromTHE_ WEB_SERVER_IP
phpseclib reads the servers server identification string before it sends it's own. This is what PuTTY does. As evidence of this here is a sample log file from PuTTY when I tried to connect to localhost:4022:
Event Log: Writing new session log (SSH packets mode) to file: putty.log
Event Log: Looking up host "127.0.0.1"
Event Log: Connecting to 127.0.0.1 port 4022
Event Log: Server version: SSH-2.0-OpenSSH_6.6p1 Ubuntu-2ubuntu1
Event Log: Using SSH protocol version 2
Event Log: We claim version: SSH-2.0-PuTTY_Release_0.63
Here are what the SSH specs say:
When the connection has been established, both sides MUST send an
identification string. This identification string MUST be
SSH-protoversion-softwareversion SP comments CR LF
Source: https://www.rfc-editor.org/rfc/rfc4253#section-4.2
Note that it does not say that one side has to send before the other side. Both sides should have the content available for retrieval immediately. If your SSH server is only going to conditionally make the content available for retrieval after the client has sent it's identification string then your SSH server is buggy. Let me know what server you're using an I'll open up a bug report on it.
In the mean time here's a modified version of phpseclib that sends the identification string first instead of reading it first:
https://github.com/terrafrost/phpseclib/tree/send-identifier-first
Let me know if that works for you. And let me know what you're using as your server.
I am building a WebService, using PHP:
Basically,
User sends a request to the server, via HTTP Request. 'request.php', ie.
Server starts php code asynchronously. 'update.php', ie.
The connection with the user is finished.
The code 'update.php' is still running, and will finish after some time.
The code 'update.php' is finished.
The problem is with php running asynchronously some external code.
Is that possible? Is there another way to do it? With shell_exec?
Please, I need insights! An elegant way is preferable.
Thank you!
The best approach is using message queue like RabbitMQ or even simple MySQL table.
Each time you add new task in front controller it goes to queue. Then update.php run by cron job fetch it from queue, process, save results and mark task as finished.
Also it will help you distribute load over time preventing from DoS caused by your own script.
You could have the user connect to update.php, generate some sort of unique ID to keep track of the process, and then call fsockopen() on itself with a special GET variable to signify that it's doing the heavy lifting rather than user interaction. Close that connection immediately, and then print out the appropriate response to the user.
Meanwhile, look for the special GET variable you specified, and when present call ignore_user_abort() and proceed with whatever operations you need in that branch of the if clause. So here's a rough skeleton of what your update.php file would look like:
<?php
if ( isset($_GET['asynch']) ) {
ignore_user_abort();
// check for $_GET['id'] and validate,
// then execute long-running code here
} else {
// generate $id here
$host = $_SERVER['SERVER_NAME'];
$url = "/update.php?asynch&id={$id}";
if ( $handle = fsockopen($host, 80, $n, $s, 5) ) {
$data = "GET {$url} HTTP/1.0\r\nHost: {$host}\r\n\r\n";
fwrite($handle, $data);
fclose($handle);
}
// return a response to the user
echo 'Response goes here';
}
?>
You could build a service with PHP.
Or launch a PHP script using bash : system("php myScript.php param param2 &")
Look into worker processes with Redis resque or gearman
I'm trying to make a paypal IPN system, this is a system of paypal to automatically check money transfers. They provide a basic system script to do it.
The system is easy, you get $_POST[] on your script, and then open a socket versus paypal, and they response to you valid or invalid word in the socket.
My problem is that opening the socket, 50% of times i'm getting connection lost. When the script connect, I don't have any problem. So I changed it to 20 trys, instead 1:
<?
//...
mail("mi#mail.com", "subject", "executing", "some headers"); //mailme when this is execute
$try = 20;
do{
$fp = #fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 15);
$try--;
}while($try>0 && !$fp);
if (!$fp) { // HTTP ERROR
mail("mi#mail.com", "subject", "error_message_not_connecting", "some headers");
} else {
mail("mi#mail.com", "subject", "connected_reading_socket", "some headers");
//fputs(..); and the loop reading working.
}
?>
In my test, it works now 100% of severals trys. But in real transfers, it doesn't work 20-30% of times. I'm getting the 1st mail, but never the second one in that fails.
I'm thinking.. If paypal only open the connection to my server 1 second, can the php script stop after some trys, and stop going on? or any idea what is wrong here?
Sending the mail can fail too, especially if you have network issues. You should log the failure conditions, for both mail() as well as your fsockopen, so you can revisit them afterwards.
Also, your fsockopen can get stuck. You have a 15 second timeout and you try 20 times, so your script will work for 20*15=300 seconds = 5 minutes, which is probably longer than your PHP script timeout -> PHP would abort your script mid-process, right? Max execution time is only 30 seconds by default in PHP.
A PHP script can be stopped with exit;.
You can pause the php script proccessing with sleep(nr_sec).
I used to get similar problems. Strange behavior when usin sockets.
Better use CURL instead, it's more stable.
http://leepeng.blogspot.com/2006/04/standard-paypal-php-integration.html
I found the error. A php can be stopped when a users close the conection to the server (usually by click stop button on browser, or in this case a socket closed by paypal).
There are 3 ways to stop a script.
1-by finish the script
2-by user closeing the conection to the server
3-by timeout
I used the function ignore_user_abort(true), and I dont have more problems.
http://php.net/manual/en/function.ignore-user-abort.php
I am trying to implement a realtime chat application using PHP . Is it possible to do it without using a persistent data storage like database or file . Basically what I need is a mediator written in PHP who
accepts messages from client browsers
Broadcasts the message to other clients
Forgets the message
You should check out Web Sockets of html5. It uses two way connection so you will not need any database or file. Any chat message comes to the server will directly sent to the other users browser without any Ajax call. But you need also to setup web socket server.
Web sockets are used in many real time applications as well. I am shortly planing to write full tutorial on that. I will notify you.
Just tried something I had never done before in response to this question. Seemed to work but I only tested it once. Instead of using a Socket I had an idea of using a shared Session variable. Basically I forced the Session_id to be the same value regardless of the user therefore they are all sharing the same data. From a quick test it seems to work. Here is what I did:
session_id('12345');
session_start();
$session_id = session_id();
$_SESSION['test'] = $_SESSION['test'] + 1;
echo "session: {$session_id} test: {$_SESSION['test']} <br />";
So my thought process was that you could simply store the chat info in a Session variable and force everyone regardless of who they are to use a shared session. Then you can simply use ajax to continually reload the current Session variable, and use ajax to edit the session variable when adding a message. Also you would probably want to set the Session to never expire or have a really long maxlifetime.
As I said I just played around with this for a few minutes to see if it would work.
You will want to use Sockets. This article will cover exactly what you want to do: http://devzone.zend.com/209/writing-socket-servers-in-php/
When I tried to solve the same problem, I went with Nginx's Push Module. I chose to go this way since I had to support older browsers (that usually won't support WebSockets) and had no confidence in setting up an appropriate solution like Socket.io behind a TCP proxy.
The workflow went like this:
The clients connect through long-polling to my /subscriber location, which is open to all.
The /publisher location only accepts connections from my own server
When a client subscribes and talks, it basically just asks a PHP script to handle whatever data is sent.
This script can do validation, authorization, and such, and then forwards (via curl) the message in a JSON format to the /publisher.
Nginx's Push Module handles sending the message back to the subscribers and the client establishes a new long-polling connection.
If I had to do this all over again, then I would definitely go the Socket.io route, as it has proper fallbacks to Comet-style long-polling and has great docs for both Client and Server scripts.
Hope this helps.
If you have a business need for PHP, then adding another language to the mix just means you then have two problems.
It is perfectly possible to run a permanent, constantly-running daemonised PHP IRCd server: I know, because I've done it, to make an online game which ran for years.
The IRC server part I used is a modified version of WaveIRCd:
http://sourceforge.net/projects/waveircd/
I daemonised it using code I made available here:
http://www.thudgame.com/node/254
That code might be overkill: I wrote it to be as rugged as I could, so it tries to daemonise using PHP's pcntl_fork(), then falls back to calling itself recursively in the background, then falls back to perl, and so on: it also handles the security restrictions of PHP's safe mode in case someone turns that on, and the security restrictions imposed by being called through cron.
You could probably strip it down to just a few lines: the bits with the comments "Daemon Rule..." - follow those rules, and you'll daemonize your process just fine.
In order to handle any unexpected daemon deaths, etc, I then ran that daemoniser every minute through cron, where it checked to see if the daemon was already running, and if so either quietly died, or if the daemon was nonresponsive, killed it and took its place.
Because of the whole distributed nature of IRC, it was nicely rugged, and gave me a multiplayer browser game with no downtime for a good few years until bit-rot ate the site a few months back. I should try to rewrite the front end in Flash and get it back up again someday, when I have time...
(I then ran another daemonizer for a PHP bot to manage the game itself, then had my game connect to it as a java applet, and talk to the bot to play the game, but that's irrelevant here).
Since WaveIRCd is no longer maintained, it's probably worth having a hunt around to find if anyone else has forked the project and is supporting it.
[2012 edit: that said, if you want your front end to be HTML5/Javascript, or if you want to connect through the same port that HTTP connects through, then your options are more limited than when using Flash or Java. In that case, take the advice of others, and use "WebSockets" (poor support in most current browsers) or the "Socket.io" project (which uses WebSockets, but falls back to Flash, or various other methods, depending what the browser has available).
The above is for situations where your host allows you to run a service on another port. In particular, many have explicit rules in their ToS against running an IRCd.]
[2019 edit: WebSockets are now widely supported, you should be fine using them. As a relevant case study, Slack is written in PHP (per https://slack.engineering/taking-php-seriously-cf7a60065329), and for some time supported the IRC protocol, though I believe that that has since been retired. As its main protocol, it uses an API based on JSON over WebSockets (https://api.slack.com/rtm). This all shows that a PHP IRCd can deliver enterprise-level performance and quality, even where the IRC protocol is translated to/from another one, which you'd expect to give poorer performance.]
You need to use some kind of storage as a buffer. It IS plausable not to use file or db (which also uses a file). You can try using php's shared memory functions, but I don't know any working solution so you'll have to do it from scratch.
Is it possible to do it without using a persistent data storage like
database or file?
It is possible but you shouldn't use. Database or file based doesn't slows down chat. It will be giving additional security to your chat application. You can make web based chat using ajax and sockets without persistent data.
You should see following posts:
Is database based chat room bad idea?
Will polling from a SQL DB instead of a file for chat application increase performance?
Using memcached as a database buffer for chat messages
persistent data in php question
https://stackoverflow.com/questions/6569754/how-can-i-develop-social-network-chat-without-using-a-database-for-storing-the-c
File vs database for storage efficiency in chat app
PHP is not a good fit for your requirements (in a normal setup like apache-php, fastcgi etc.), because the PHP script gets executed from top to bottom for every request and cannot maintain any state between the requests without the use of external services or databases/files (Except e.g. http://php.net/manual/de/book.apc.php, but it is not intended for implementing a chat and will not scale to multiple servers.)
You should definitely look at Node.js and especially the Node.js module Socket.IO (A Websocket library). It's incredibly easy to use and rocks. Socket.IO can also scale to multiple chat servers with an optional redis backend, which means it's easier to scale.
Trying to use $_SESSION with a static session id as communication channel is not a solution by the way, because PHP saves the session data into files.
One solution to achieving this is by writing a PHP socket server.
<?php
// Set time limit to indefinite execution
set_time_limit (0);
// Set the ip and port we will listen on
$address = '192.168.0.100';
$port = 9000;
$max_clients = 10;
// Array that will hold client information
$clients = Array();
// Create a TCP Stream socket
$sock = socket_create(AF_INET, SOCK_STREAM, 0);
// Bind the socket to an address/port
socket_bind($sock, $address, $port) or die('Could not bind to address');
// Start listening for connections
socket_listen($sock);
// Loop continuously
while (true) {
// Setup clients listen socket for reading
$read[0] = $sock;
for ($i = 0; $i < $max_clients; $i++)
{
if ($client[$i]['sock'] != null)
$read[$i + 1] = $client[$i]['sock'] ;
}
// Set up a blocking call to socket_select()
$ready = socket_select($read,null,null,null);
/* if a new connection is being made add it to the client array */
if (in_array($sock, $read)) {
for ($i = 0; $i < $max_clients; $i++)
{
if ($client[$i]['sock'] == null) {
$client[$i]['sock'] = socket_accept($sock);
break;
}
elseif ($i == $max_clients - 1)
print ("too many clients")
}
if (--$ready <= 0)
continue;
} // end if in_array
// If a client is trying to write - handle it now
for ($i = 0; $i < $max_clients; $i++) // for each client
{
if (in_array($client[$i]['sock'] , $read))
{
$input = socket_read($client[$i]['sock'] , 1024);
if ($input == null) {
// Zero length string meaning disconnected
unset($client[$i]);
}
$n = trim($input);
if ($input == 'exit') {
// requested disconnect
socket_close($client[$i]['sock']);
} elseif ($input) {
// strip white spaces and write back to user
$output = ereg_replace("[ \t\n\r]","",$input).chr(0);
socket_write($client[$i]['sock'],$output);
}
} else {
// Close the socket
socket_close($client[$i]['sock']);
unset($client[$i]);
}
}
} // end while
// Close the master sockets
socket_close($sock);
?>
You would execute this by running it through command line and would always have to run for your PHP clients to connect to it. You could then write a PHP client that would connect to the socket.
<?php
$fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);
if (!$fp) {
echo "$errstr ($errno)<br />\n";
} else {
$out = "GET / HTTP/1.1\r\n";
$out .= "Host: www.example.com\r\n";
$out .= "Connection: Close\r\n\r\n";
fwrite($fp, $out);
while (!feof($fp)) {
echo fgets($fp, 128);
}
fclose($fp);
}
?>
You would have to use some type of ajax to call with jQuery posting the message to this PHP client.
http://devzone.zend.com/209/writing-socket-servers-in-php/
http://php.net/manual/en/function.fsockopen.php
Better use a node.js server for this. WebSockets aren't cross-browser nowadays (except socket.io for node.js that works perfect)
in short answer, you can't.
the current HTTP/HTML implementation doesn't support the pushstate so the algorithm of your chat app should follow :
A: sent message
B,C,D: do while a new message has been sent get this message.
so the receivers always have to make a new request and check if a new message has been sent. (AJAX Call or something similar )
so always there are a delay between the sent event and the receive event.
which means the data must be saved in something global, like db or file system.
take a look for :
http://today.java.net/article/2010/03/31/html5-server-push-technologies-part-1
You didn't say it had to all be written it PHP :)
Install RabbitMQ, and then use this chat implementation built on top of websockets and RabbitMQ.
Your PHP is pretty much just 'chat room chrome'. It's possible most of your site would fit within the 5 meg limit of offline HTML5 content, and you have a very flexible (and likely more robust than if you did it yourself) chat system.
It even has 20 messages of chat history if you leave the room.
https://github.com/videlalvaro/rabbitmq-chat
If You need to use just PHP, then You can store chat messages in session variables, session could be like object, storing a lot of information.
If You can use jQuery then You could just append paragraph to a div after message has been sent, but then if site is refreshed, messages will be gone.
Or combining, store messages in session and update that with jQuery and ajax.
Try looking into socket libraries like ZeroMQ they allow for instant transport of the message, and are quicker than TCP, and is realtime. Their infrastructure allows for instant data send between points A and B, without the data being stored anywhere first (although you can still choose to).
Here's a tutorial for a chat client in ZeroMQ