FindProxyForURL - Parse a PAC (proxy auto config) file in PHP

Proxy servers are used in most companies as a gateway to the internet, that do other things like cache results and check web requests and responses.  A PAC file is a Javascript file evaluated by web browsers to determine which proxy server to use for certain URL's.  For example, some URL's can go straight to the internet, or a local server, and others must be sent to one of the proxy servers.

One day I needed to run this javascript from php on the web server, to find the proxy in the same way; then php could also follow the same proxy rules as desktop computers in my office.

Here's a working example of using the php_spidermonkey extension to run a proxy auto config script (javascript) in PHP.



All you need is a PAC file to test it.  You can write your own following instructions across the web, here is a guide: http://findproxyforurl.com/pac-functions/

There is more information and Windows builds of php_spidermonkey in this article: Javascript in PHP on Windows with php_spidermonkey.  Install the extension dll in PHP in the usual way.

Here is a snippet of code that uses the class 'CProxy' (defined underneath) which executes the Javascript PAC function FindProxyForURL:

Code formatted by http://hilite.me/

use DEMO\PAC\CProxy; // namespace, if required.

$proxy = new CProxy();
$proxy->LoadPAC('C:\proxy.pac'); // pac file is usually a URL
$test = $proxy->FindProxyForAddress('http://www.google.com/', true);
echo $test;

/*  
Assuming your PAC file contained something like this:

function FindProxyForURL(url, host)
{
   if ( shExpMatch(host, "*.google.*") )
   {
      return "PROXY 10.20.30.40:8000; DIRECT";
   }
   return "DIRECT";
}

this snippet would print:
    PROXY 10.20.30.40:8000; DIRECT
*/

Definition of class CProxy - it utilises and demonstrates some of the following:

1. PHP 5.4 - uses namespaces to show how they work in this scenario, and traits.
2. php_spidermonkey javascript interpreter
3. PAC (proxy-auto-config) functions 

<?php
/* This example uses a namespace, just to show how it works inside namespaces.  
Namespace can be removed. */

namespace DEMO\PAC;
use \JSContext, \Exception;

if ( !defined('JSVERSION_DEFAULT') )
{
   error_log(__FILE__ . 'CProxy not loaded, php_spidermonkey extension not detected!');
   return;
}

// global function to escape javascript strings: 

function js($str, $quotes = '\'"')
{
    return addcslashes($str,"\\$quotes\n\r<>"); 
} 

class CProxy 
{
    use PACFunctions; // include traits in this class, defined below.
    
    private $pac, $js, $proxyconfig;
    
    function __construct($pacfile=NULL, $strictJavascript=false)
    {
        // requires php_spidermonkey.dll extension.
        $js = new JSContext();
        
        if ( $strictJavascript )
        {
            $opts = $js->getOptions() | JSOPTION_STRICT | JSOPTION_WERROR;
            $prev = $js->setOptions($opts);
        }
        
        $js->registerFunction(__NAMESPACE__.'\CProxy::myIpAddress', 'myIpAddress');
        $js->registerFunction(__NAMESPACE__.'\CProxy::isPlainHostName', 'isPlainHostName');
        $js->registerFunction(__NAMESPACE__.'\CProxy::dnsDomainIs', 'dnsDomainIs');
        $js->registerFunction(__NAMESPACE__.'\CProxy::localHostOrDomainIs', 'localHostOrDomainIs');
        $js->registerFunction(__NAMESPACE__.'\CProxy::isResolvable', 'isResolvable');
        $js->registerFunction(__NAMESPACE__.'\CProxy::isInNet', 'isInNet');
        $js->registerFunction(__NAMESPACE__.'\CProxy::dnsResolve', 'dnsResolve');
        $js->registerFunction(__NAMESPACE__.'\CProxy::dnsDomainLevels', 'dnsDomainLevels');
        $js->registerFunction(__NAMESPACE__.'\CProxy::shExpMatch', 'shExpMatch');
        $js->registerFunction(__NAMESPACE__.'\CProxy::weekdayRange', 'weekdayRange');
        $js->registerFunction(__NAMESPACE__.'\CProxy::dateRange', 'dateRange');
        $js->registerFunction(__NAMESPACE__.'\CProxy::timeRange', 'timeRange');
        // I don't know what ProxyConfig is used for:
        $this->proxyconfig = new \stdClass();
        $this->proxyconfig->bindings = array();
        $js->assign('ProxyConfig', $this->proxyconfig);
        
        $this->js = $js;
        $this->LoadPAC($pacfile);
    }
    
    function FindProxyForAddress($address, $raw=false)
    {
        /* returns an array of proxy servers 
           (from preg_match_all),
           or, if $raw is true, returns
           the original string returned by 
           FindProxyForURL function. */

        if ( !$this->pac )
            return false;
        
        $parts = parse_url($address);
        $url = $address;
        
        if ( !isset($parts['port']) )
        {
            $port = '';
        }
        else if ( ($port=$parts['port']) )
        {
            $port = ':' . $port;
        } 
        
        if ( !isset($parts['host']) )
        {
            /* $address is badly formed, not sure if this is right, but 
             * return it from the beginning to the first slash. */
            if ( !isset($parts['path']) )
                return false;
            $parts['host'] = preg_replace('/(.*?)(?>\/.*$|$)/', '$1', $parts['path']);     
        }
        
        $host = $parts['host'] . $port;

        try
        {
            if ( !($rv=$this->js->evaluateScript('FindProxyForURL(\'' . js($url) . '\', \'' . js($host) . '\');', 'FindProxyForURL')) || $raw )
            {
                return $rv;
            }
        }
        catch ( Exception $ex )
        {
            return false;
        }
        return self::ReadPacResult($rv);
    }
    
    function LoadPAC($pac)
    {
        if ( $this->pac )
        {
            return NULL; // already loaded
        }
        
        if ( $pac === NULL || !$this->js )
        {
            return false; // param error or not initialised properly
        }
        
        if ( !($script = file_get_contents($pac)) )
        {
            return false; // cannot read PAC file
        }
        
        try 
        {
            $rv = $this->js->evaluateScript($script, $pac);
        }
        catch ( Exception $ex )
        {
            return false;
        }
        
        $this->pac = $script;
        return true;
    }
    
    public static function ReadPacResult($pacres)
    {
        if ( !$pacres )
            return false;
        
        // $pacres should be something like
        // PROXY 1.2.3.4:8080; PROXY 1.2.3.5:8080; DIRECT
        if ( !preg_match_all('/(PROXY|SOCKS|DIRECT)\s*([^;]*|.*?$)/ui', $pacres, $matches, PREG_SET_ORDER) )
        {
            return false;
        }
        return $matches;
    }
}
?>

PAC functions written as a trait class (remember - not tested very much!):

Code formatted by http://hilite.me/

<?php
/* Define the PAC traits used in class CProxy, above. */

namespace DEMO\PAC;
use \DateTime, \DateTimeZone, \Exception;

trait PACFunctions
{
   private static $s_myIP;

 /* 
  * PAC functions:
  *  'global' functions to replicate javascript PAC environment... 
 */

   static function myIpAddress()
   {
       if ( self::$s_myIP )
       {
           return self::$s_myIP;
       }

       $vars = array('SERVER_ADDR', 'LOCAL_ADDR');
       $ip = NULL;
       $bestip = '0.0.0.0';

       foreach ( $vars as $var )
       {
           if ( isset($_SERVER[$var]) )
           {
               $ip = $_SERVER[$var];
               if ( !empty($ip) )
               {
                   if ( $ip != '127.0.0.1' )
                   {
                       return (self::$s_myIP = $ip);
                   }
                   $bestip = $ip;
               }
           }
       }

       if ( ($hn = gethostname()) && ($ip = gethostbyname($hn)) && $ip !== $hn )
       {
           return (self::$s_myIP=$ip);
       }

       return (self::$s_myIP=$bestip);
    }

    static function isPlainHostName( $host )
    {
        return strpos($host, '.')===false;
    }

    static function shExpMatch($host, $pattern)
    {
        $parts = explode('*', $pattern);
        $pattern = '';
        foreach( $parts as $part )
        {
            if ( $part === '' )
            {
                $pattern .= '.*?';
            }
            else
            {
                $pattern .= preg_quote($part, '/');
            }
        }
        return preg_match('/^'.$pattern.'$/ui', $host)===1;
    }

    static function isResolvable($host)
    {
        if ( ip2long($host) !== false )
        {
            return true;
        }
        $test = gethostbyname($host);
        return $test && ip2long($test) !== false;
    }

    static function isInNet($host, $ip, $subnet)
    {
        if ( ($longhost = ip2long($host)) === false )
        {
            $host = gethostbyname($host);
            if ( ($longhost = ip2long($host))===false )
            {
                return false;
            }
        }
        $longip = ip2long($ip);
        $longsub = ip2long($subnet);
        return ($longhost&$longsub) == $longip;
    }

    static function dnsDomainIs($host, $domain)
    {
        $len = strlen($domain);
        return $len <= strlen($host) && substr($host, -$len)==$domain;
    }

    static function localHostOrDomainIs($host, $domain)
    {
        return strcasecmp($domain, substr($host, 0, strlen($domain)))===0;
    }

    static function dnsResolve($host)
    {
        return gethostbyname($host);
    }

    static function dnsDomainLevels($host)
    {
        return substr_count($host, '.');
    }

    static function weekdayRange($fr, $to=NULL, $gmt=NULL)
    {
        $days = array('mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun');
        $fr = strtolower(substr($fr,0,3));
        if ( $gmt )
            $gmt = strtoupper($gmt);
        if ( $to === NULL )
            $to = $fr;
        else if ( strcasecmp($to, 'GMT')==0 )
        {
            $to = $fr;
            $gmt = 'GMT';
        }
        else
            $to = strtolower(substr($to,0,3));

        if ( $gmt == 'GMT' )
        {
            $tzn = 'UTC';
        }
        else if ( !($tzn = ini_get('date.timezone')) )
        {
            $tzn = 'Europe/London';
        }
        $tz = new DateTimeZone($tzn);
        $today = strtolower( (new DateTime('now',$tz))->format('D') );

        foreach ( $days as $wd=>$day )
        {
            if ( $fr == $day )
                $fr = $wd+1;
            if ( $to == $day )
                $to = $wd+1;
            if ( $today == $day )
                $today = $wd+1;
        }

        if ( !(int)$today || !(int)$fr || !(int)$to )
            return false;

        // FRI = 5
        // MON = 1
        // THU = 4
        // is THU in FRI - MON ??
        if ( $fr > $to )
        {
            return $today >= $fr || $today <= $to;
        }

        return $today >= $fr && $today <= $to;
    }

    static function dateRange($day1, $month1=NULL, $year1=NULL, $day2=NULL, $month2=NULL, $year2=NULL, $gmt=NULL)
    {
        $args = array($day1, $month1, $year1, $day2, $month2, $year2, $gmt);

        $RationaliseArgs = function(&$arg)
        {
            $isgmt = 0;

            for ( $ct=0 ; $ct < 6 ; $ct += 3 )
            {
                if ( (int)$arg[$ct] > 31 )
                {
                    // 1st arg is a year, insert blank day and month
                    array_splice($arg, $ct, 0, array(0,''));
                }
                else if ( (int)$arg[$ct] )
                {
                    // 1st arg is day
                    if ( (int)$arg[$ct+1] )
                    {
                        // 2nd arg must be a day.   2nd arg can't be year if 1st arg is a day.
                        array_splice($arg, $ct+1, 0, array('',0)); // insert blank month and year
                    }
                    else if ( $arg[$ct+1]===NULL || strcasecmp($arg[$ct+1], 'GMT')==0 )
                    {
                        // nothing else after the day.
                        array_splice($arg, $ct+1, 0, array('',0)); // insert blank month and year.
                    }
                    else if ( (int)$arg[$ct+2] && (int)$arg[$ct+2] <= 31 ) // month supplied, test what's after month
                    {
                        // month followed by day...  insert blank year...
                        array_splice($arg, $ct+2, 0, array(0)); // insert empty year1 and shift arg2 to 2nd date.
                    }
                }
                else if ( is_string($arg[$ct]) )
                {
                    if ( strcasecmp($arg[$ct], 'GMT')==0 )
                    {
                        if ( !$ct )
                        {
                            return false; // error, 1st arg cannot be 'GMT'.
                        }
                        break;
                    }
                    // 1st arg is month
                    array_splice($arg, $ct, 0, array(0)); // insert a blank day.
                    if ( (int)$arg[$ct+2] <= 31 ) // month not followed by a year
                    {
                        // insert a blank year...
                        array_splice($arg, $ct+2, 0, array(0));
                    }
                }
                else
                {
                    if ( $ct && $arg[$ct] === NULL ) // only 1 date supplied.  ok.
                        return 1;
                    return false; // error
                }
            }

            if ( strcasecmp($arg[$ct], 'GMT')==0 )
            {
                $isgmt = 1;
                $arg[$ct] = 'GMT';
            }

            array_splice($arg, 7);

            return $ct/3;
        };

        if ( !($cd = $RationaliseArgs($args, $gmt)) )
        {
            return false;
        }

        list($day1, $month1, $year1, $day2, $month2, $year2, $gmt) = $args;

        if ( $gmt == 'GMT' )
        {
            $tzn = 'UTC';
        }
        else if ( !($tzn = ini_get('date.timezone')) )
        {
            $tzn = 'Europe/London';
        }
        $tz = new DateTimeZone($tzn);
        $now = new DateTime('now',$tz);

        $thisyear = $now->format('Y');
        $thismonth = 'Jan'; //  a month with 31 days.
        $thisday = $now->format('d');

        try
        {
            $from = new \DateTime(($year1 ? $year1 : $thisyear) . '-' . ($month1 ? $month1 : $thismonth) . '-' . ($day1 ? $day1 : $thisday), $tz);
            if ( !$day1 )
                $day2 = 0;
            if ( !$month1 )
                $month2 = '';
            if ( !$year1 )
                $year2 = 0;
            if ( $day2 || $month2 || $year2 )
            {
                $to = new \DateTime(($year2 ? $year2 : $thisyear) . '-' . ($month2 ? $month2 : $thismonth) . '-' . ($day2 ? $day2 : $thisday), $tz);
            }
            else
                $to = NULL;
        }
        catch ( Exception $ex )
        {
            return false; // data error, an arg is incorrect
        }

        $dateformat = ($year1 ? 'Y' : '') . ($month1 ? 'm' : '') . ($day1 ? 'd' : '');

        $test = $now->format($dateformat);
        $lhs = $from->format($dateformat);

        if ( !$to )
        {
            return $test == $lhs;
        }

        $rhs = $to->format($dateformat);
        if ( $rhs < $lhs && $dateformat{0} != 'Y' )
        {
            return $test >= $lhs || $test <= $rhs;
        }
        return $test >= $lhs && $test <= $rhs;
    }

    static function timeRange($hour1, $min1=NULL, $sec1=NULL, $hour2=NULL, $min2=NULL, $sec2=NULL, $gmt=NULL)
    {
        $args = array($hour1, $min1, $sec1, $hour2, $min2, $sec2, $gmt);
        for ( $ct=0 ; $ct < count($args) && $args[$ct] !== NULL && strcasecmp($args[$ct], 'GMT') ; ++$ct ) ;

        if ( !$ct )
            return false; // arg error

        if ( ($gmt = (strcasecmp($args[$ct], 'GMT')==0))  )
        {
            $tzn = 'UTC';
        }
        else if ( !($tzn = ini_get('date.timezone')) )
        {
            $tzn = 'Europe/London';
        }
        $tz = new DateTimeZone($tzn);
        $now = new DateTime('now',$tz);
        
        /* $ct is the number of args (excluding any 'GMT' value).
         * if 6 args supplied, full time specified, else... */
        if ( $ct == 4 ) // range of hours+minutes
        {
            // hour and minute supplied
            $min2 = $hour2;
            $hour2 = $sec1;
            $sec1 = $sec2 = 0;
            $fmt = 'Hi';
        }
        else if ( $ct < 3 ) // range of hours (1 or 2)
        {
            $hour2 = ($ct==2 ? $min1 : $hour1);
            $min1 = $sec1 = $min2 = $sec2 = 0;
            $fmt = 'H';
        }
        else if ( $ct == 6 )
        {
            $fmt = 'His';
        }
        else
        {
            return false; // parameters not specified properly
        }
        
        try
        {
            $lhs = new \DateTime( ($dt=$now->format('Y-m-d')) . ' ' . (int)$hour1 . ':' . (int)$min1 . ':' . $sec1, $tz);
            $rhs = (( $ct == 1 ) ? NULL : new \DateTime( $dt . ' ' . (int)$hour2 . ':' . (int)$min2 . ':' . $sec2, $tz));
        }
        catch ( Exception $ex )
        {
            // datetime not recognised, so parameter probably out of range
            return false;
        }

        $nowtime = $now->format($fmt);
        $ltime = $lhs->format($fmt);
        if ( $rhs === NULL )
        {
            return $nowtime == $ltime;
        }
        $rtime = $rhs->format($fmt);
        if ( $ltime > $rtime )
        {
            return $nowtime >= $ltime || $nowtime <= $rtime;
        }
        return $nowtime >= $ltime && $nowtime <= $rtime;
    }
}

?>