php telnet no response from script - php

Question

I'm running PHP5 on Windows XP Professional. I'm trying to write a telnet php script which simply connects, sends a text string and grabs the response buffer and outputs it. I'm using the telnet class file from here:
http://cvs.adfinis.ch/cvs.php/phpStreamcast/telnet.class.php
which i found in another thread.
<?php
error_reporting(255);
ini_set('display_errors', true);
echo "1<br>";
require_once("telnet_class.php");
$telnet = new Telnet();
$telnet->set_host("10.10.5.7");
$telnet->set_port("2002");
$telnet->connect();
//$telnet->wait_prompt();
$telnet->write('SNRD 1%0d');
echo "3<br>";
$result = $telnet->get_buffer();
echo $result;
print_r($result);
// flush_now();
echo "4<br>";
$telnet->disconnect();
?>
I'm not receiving any kind of errors or response. If I send an invalid string, I should get an 'ERR' response in the least however I don't even get that. Any ideas what i could be doing wrong? If I do the same thing from the command prompt, I receive the string output I need. Could this is because the write function is sending

Answer 1

After some reading in the source code and on the original (french) site referred to in the header....
<?php
error_reporting(255);
ini_set('display_errors', true);
echo "1<br>";
require_once("telnet_class.php");
$telnet = new Telnet();
$telnet->set_host("10.10.5.7");
$telnet->set_port("2002");
if ($telnet->connect() != TELNET_OK) {
printf("Telnet error on connect, %s\n",$telnet->get_last_error());
}
//$telnet->wait_prompt();
if ($telnet->write('SNRD 1' . "\xd") != TELNET_OK) {
printf("Telnet error on write, %s\n",$telnet->get_last_error());
}
// read to \n or whatever terminates the string you need to read
if ($telnet->read_to("\n") != TELNET_OK) {
printf("Telnet error on read_to, %s\n",$telnet->get_last_error());
}
echo "3<br>";
$result = $telnet->get_buffer();
echo $result;
print_r($result);
// flush_now();
echo "4<br>";
$telnet->disconnect();
?>
Okay, explanation: get_buffer() does just that, read what's in the buffer. To get something in the buffer you have to execute read_to($match) who will read into buffer up to $match. After that, get_buffer should give you the desired string.
EDIT:
if you cannot find some string that follows the string you are interested in read_to will end in an error due to this part of the read_to method (translation of original french comment is mine):
if ($c === false){
// plus de caracteres a lire sur la socket
// --> no more characters to read on the socket
if ($this->contientErreur($buf)){
return TELNET_ERROR;
}
$this->error = " Couldn't find the requested : '" . $chaine . "', it was not in the data returned from server : '" . $buf . "'" ;
$this->logger($this->error);
return TELNET_ERROR;
}
Meaning that when the socket is closed without a match of the requested string, TELNET_ERROR will be returned. However, the string you're looking for should at that point be in the buffer.... What did you put in read_to's argument? "\n" like what I did or just "" ?
EDIT2 :
there's also a problem with get_buffer. IMO this class is not really a timesaver ;-)
//------------------------------------------------------------------------
function get_buffer(){
$buf = $this->buffer;
// cut last line (is always prompt)
$buf = explode("\n", $buf);
unset($buf[count($buf)-1]);
$buf = join("\n",$buf);
return trim($buf);
}
It will throw away the last line of the response, in your case the one that contains the
answer.
I suggest to add a "light" version of get_buffer to the class, like this
//------------------------------------------------------------------------
function get_raw_buffer(){
return $this->buffer;
}
and do the necessary trimming/searching in the result yourself.
You might also want to add the following constant
define ("TELNET_EOF", 3);
and change read_to like this
...
if ($c === false){
// plus de caracteres a lire sur la socket
if ($this->contientErreur($buf)){
return TELNET_EOF;
}
$this->error = " Couldn't find the requested : '" . $chaine . "', it was not in the data returned from server : '" . $buf . "'" ;
$this->logger($this->error);
return TELNET_EOF;
}
...
in order to treat that special case yourself (a result code TELNET_EOF doesn't have to be treated as an error in your case). So finally your code should look more or less like this:
// read to \n or whatever terminates the string you need to read
if ($telnet->read_to("\n") == TELNET_ERROR) {
printf("Telnet error on read_to, %s\n",$telnet->get_last_error()); } echo "3<br>";
} else {
$result = $telnet->get_raw_buffer();
echo $result;
print_r($result);
}

Answer 2

Have you checked how the telnet class works? Maybe it wasn't designed to run under windows. If it's a simple socket that you're speaking to, maybe consider using a regular socket-connection instead.
http://se2.php.net/sockets
If you open up a socket which you don't close, you should se an entry in netstat as long as your script is running.
netstat -na|find ":2002"

Answer 3

You can't insert hex values like that. The remote process just sees
SRND 1%0d
and now it's waiting for the line to be terminated. Try this
$telnet->write('SNRD 1' . "\r");
or
$telnet->write("SNRD 1\xd");
The double quotes are quite critical, see here
EDIT:
you might try adding some error reporting as right now you don't really check much (error_reporting won't show anything on the errors in the telnet class).... For example:
<?php
error_reporting(255);
ini_set('display_errors', true);
echo "1<br>";
require_once("telnet_class.php");
$telnet = new Telnet();
$telnet->set_host("10.10.5.7");
$telnet->set_port("2002");
if ($telnet->connect() != TELNET_OK) {
printf("Telnet error on connect, %s\n",$telnet->get_last_error());
}
//$telnet->wait_prompt();
if ($telnet->write('SNRD 1' . "\xd") != TELNET_OK) {
printf("Telnet error on write, %s\n",$telnet->get_last_error());
}
echo "3<br>";
$result = $telnet->get_buffer();
echo $result;
print_r($result);
// flush_now();
echo "4<br>";
$telnet->disconnect();
?>
also, are you sure you need \r\n line termination? write is defined as
function write($buffer, $valeurLoggee = "", $ajouterfinLigne = true){
and does
if ($ajouterfinLigne){
$buffer .= "\n";
}
?
Also, did you test the host and port with the command line telnet client? Like
telnet 10.10.5.7 2002
?