PHPSECLIB call to undefined function crypt_random_string() - php

Question

I'm trying to upload a file to sftp server using phpseclib library. Here's the code I've written
set_include_path(get_include_path() . PATH_SEPARATOR . 'phpseclib0.3.5');
$fileName = "sImg3.jpeg";
$fileData = file_get_contents($fileName);
$b64Data = base64_encode($fileData);
// upload the file to ftp server
include('Net/SFTP.php');
include_once('include/config.php'); // contains sftp connection details
$sftp = new Net_SFTP($ftpHost);
if (!$sftp->login($ftpUser, $ftpPasswd))
{
die("Failed to connect to SFTP server");
}
else
{
$sftp->put($filename,$b64Data);
echo "Uploaded the file (".$filename.")\n";
}
When I try to run this, I'm getting:
PHP Fatal error: Call to undefined function crypt_random_string() in
/var/www/phpseclib0.3.5/Net/SSH2.php on line 1014
I've installed php5-mcrypt and phpseclib. Do I need to install any other dependencies for phpseclib? Please let me know.
Thanks much in advance,
Regards,
Sudheer

Answer 1

crypt_string_random is defined in Crypt/Random.php:
https://github.com/phpseclib/phpseclib/blob/0.3.5/phpseclib/Crypt/Random.php
But then again Net_SSH2 auto-includes Crypt/Random.php:
https://github.com/phpseclib/phpseclib/blob/0.3.5/phpseclib/Net/SSH2.php#L749
And Net_SFTP extends Net_SSH2:
https://github.com/phpseclib/phpseclib/blob/0.3.5/phpseclib/Net/SFTP.php#L253
And Net_SSH2 does a require_once so if anything you should be getting some sort of "file not found" error, if you're getting an error at all, not a "function not defined" error..

Answer 2

The problem is caused by how PHP handles nested include statements and relative paths. If you look at the current phpseclib programming, at least 'some' of the includes still use include() instead of require_once() which silently fail - which is why you don't see the errors about failing includes.
It all comes down to how PHP resolves relative pathing of nested includes - using the starting location of the parent script or the starting location of the current/child script. More info on the conundrum of PHP nested includes with relative pathing here:
php nested include behavior
When I ran into this problem myself, I worked around it by promoting /phpseclib out of it's own subfolder and into my existing /includes folder. Then I only ever include phpseclib files from within php scripts in my /includes folder so that the relative paths in phpseclib's nested include statements will work.