http://blog.unijimpe.net/detectar-el-browser-con-php/

<?php

/**
 * Class to detect which browser is currently accessing the page/site
 * @author Paul Scott
 * This class is very loosely based on scripts by Gary White
 * @copyright Paul Scott
 * @package browser
 */

class browser
{
    /**
     * @var string $name
     */
    var $name = NULL;

    /**
     * @var string $version
     */
    var $version = NULL;

    /**
     * @var $useragent
     */
    var $useragent = NULL;

    /**
     * @var string $platform
     */
    var $platform;

    /**
     * @var string aol
     */
    var $aol = FALSE;

    /**
     * @var string browser
     */
    var $browsertype;

    /**
     * Class constructor
     * @param void
     * @return void
     */
    function browser()
    {
        $agent = $_SERVER['HTTP_USER_AGENT'];
        //set the useragent property
        $this->useragent = $agent;
    }

    /**
     * Method to get the browser details from the USER_AGENT string in
     * the PHP superglobals
     * @param void
     * @return string property platform
     */
    function getBrowserOS()
    {
        $win = eregi("win", $this->useragent);
        $linux = eregi("linux", $this->useragent);
        $mac = eregi("mac", $this->useragent);
        $os2 = eregi("OS/2", $this->useragent);
        $beos = eregi("BeOS", $this->useragent);

        //now do the check as to which matches and return it
        if($win)
        {
            $this->platform = "Windows";
        }
        elseif ($linux)
        {
            $this->platform = "Linux";
        }
        elseif ($mac)
        {
            $this->platform = "Macintosh";
        }
        elseif ($os2)
        {
            $this->platform = "OS/2";
        }
        elseif ($beos)
        {
            $this->platform = "BeOS";
        }
        return $this->platform;
    }

    /**
     * Method to test for Opera
     * @param void
     * @return property $broswer
     * @return property version
     * @return bool false on failure
     */
    function isOpera()
    {
        // test for Opera
        if (eregi("opera",$this->useragent))
        {
            $val = stristr($this->useragent, "opera");
            if (eregi("/", $val)){
                $val = explode("/",$val);
                $this->browsertype = $val[0];
                $val = explode(" ",$val[1]);
                $this->version = $val[0];
            }else{
                $val = explode(" ",stristr($val,"opera"));
                $this->browsertype = $val[0];
                $this->version = $val[1];
            }
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for FireFox
     * @param void
     * @return bool false on failure
     */
    function isFirefox()
    {
        if(eregi("Firefox", $this->useragent))
        {
            $this->browsertype = "Firefox";
            $val = stristr($this->useragent, "Firefox");
            $val = explode("/",$val);
            $this->version = $val[1];
            return true;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for Konquerer
     * @param void
     * @return prop $browser
     * @return prop $version
     * @return bool true on success
     */
    function isKonqueror()
    {
        if(eregi("Konqueror",$this->useragent))
        {
            $val = explode(" ",stristr($this->useragent,"Konqueror"));
            $val = explode("/",$val[0]);
            $this->browsertype = $val[0];
            $this->version = str_replace(")","",$val[1]);
            return TRUE;
        }
        else {
            return FALSE;
        }

    }//end func

    /**
     * Method to check for Internet Explorer v1
     * @param void
     * @return bool true on success
     * @return prop $browsertype
     * @return prop $version
     */
    function isIEv1()
    {
        if(eregi("microsoft internet explorer", $this->useragent))
        {
            $this->browsertype = "MSIE";
            $this->version = "1.0";
            $var = stristr($this->useragent, "/");
            if (ereg("308|425|426|474|0b1", $var))
            {
                $this->version = "1.5";
            }
            return TRUE;
        }
        else {
            return FALSE;
        }
    }//end function

    /**
     * Method to check for Internet Explorer later than v1
     * @param void
     * @return bool true on success
     * @return prop $browsertype
     * @return prop $version
     */
    function isMSIE()
    {
        if(eregi("msie", $this->useragent) && !eregi("opera",$this->useragent))
        {
            $this->browsertype = "MSIE";
            $val = explode(" ",stristr($this->useragent,"msie"));
            $this->browsertype = $val[0];
            $this->version = $val[1];

            return TRUE;
        }
        else {
            return FALSE;
        }
    }//end function

    /**
     * Method to check for Galeon
     * @param void
     * @return bool true on success
     */
    function isGaleon()
    {
        if(eregi("galeon",$this->useragent))
        {
            $val = explode(" ",stristr($this->useragent,"galeon"));
            $val = explode("/",$val[0]);
            $this->browsertype = $val[0];
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }//end func

    /**
     * Now we do the tests for browsers I can't test...
     * If someone finds a bug, please report it ASAP to me please!
     */

    /**
     * Method to check for WebTV browser
     * @param void
     * @return bool true on success
     * @return prop $browsertype
     * @return prop $version
     */
    function isWebTV()
    {
        if(eregi("webtv",$this->useragent))
        {
            $val = explode("/",stristr($this->useragent,"webtv"));
            $this->browsertype = $val[0];
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for BeOS's NetPositive
     * @param void
     * @return bool true on success
     * @return prop $browsertype
     * @return prop $version
     */
    function isNetPositive()
    {
        if(eregi("NetPositive", $this->useragent))
        {
            $val = explode("/",stristr($this->useragent,"NetPositive"));
            $this->platform = "BeOS";
            $this->browsertype = $val[0];
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for MSPIE (Pocket IE)
     * @param void
     * @return bool true on success
     */
    function isMSPIE()
    {
        if(eregi("mspie",$this->useragent) || eregi("pocket", $this->useragent))
        {
            $val = explode(" ",stristr($this->useragent,"mspie"));
            $this->browsertype = "MSPIE";
            $this->platform = "WindowsCE";
            if (eregi("mspie", $this->useragent))
                $this->version = $val[1];
            else {
                $val = explode("/",$this->useragent);
                $this->version = $val[1];
            }
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to test for iCab
     * @param void
     * @return bool true on success
     */
    function isIcab()
    {
        if(eregi("icab",$this->useragent))
        {
            $val = explode(" ",stristr($this->useragent,"icab"));
            $this->browsertype = $val[0];
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to test for the OmniWeb Browser
     * @param void
     * @return bool True on success
     */
    function isOmniWeb()
    {
        if(eregi("omniweb",$this->useragent))
        {
            $val = explode("/",stristr($this->useragent,"omniweb"));
            $this->browsertype = $val[0];
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for Phoenix Browser
     * @param void
     * @return bool true on success
     */
    function isPhoenix()
    {
        if(eregi("Phoenix", $this->useragent))
        {
            $this->browsertype = "Phoenix";
            $val = explode("/", stristr($this->useragent,"Phoenix/"));
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for Firebird
     * @param void
     * @return bool true on success
     */
    function isFirebird()
    {
        if(eregi("firebird", $this->useragent))
        {
            $this->browsertype = "Firebird";
            $val = stristr($this->useragent, "Firebird");
            $val = explode("/",$val);
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for Mozilla alpha/beta
     * @param void
     * @return bool true on success
     */
    function isMozAlphaBeta()
    {
        if(eregi("mozilla",$this->useragent) &&
           eregi("rv:[0-9].[0-9][a-b]",$this->useragent) &&
           !eregi("netscape",$this->useragent))

        {
            $this->browsertype = "Mozilla";
            $val = explode(" ",stristr($this->useragent,"rv:"));
            eregi("rv:[0-9].[0-9][a-b]",$this->useragent,$val);
            $this->version = str_replace("rv:","",$val[0]);
            return TRUE;
        }
        else {
            return FALSE;
        }
    }//end function

    /**
     * Method to check for Mozilla Stable versions
     * @param void
     * @return bool true on success
     */
    function isMozStable()
    {
        if(eregi("mozilla",$this->useragent) &&
           eregi("rv:[0-9]\.[0-9]",$this->useragent) &&
           !eregi("netscape",$this->useragent))
        {
            $this->browsertype = "Mozilla";
            $val = explode(" ",stristr($this->useragent,"rv:"));
            eregi("rv:[0-9]\.[0-9]\.[0-9]",$this->useragent,$val);
            $this->version = str_replace("rv:","",$val[0]);
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Method to check for Lynx and Amaya
     * @param void
     * @return bool true on success
     */
    function isLynx()
    {
        if(eregi("libwww", $this->useragent))
        {
            if (eregi("amaya", $this->useragent))
            {
                $val = explode("/",stristr($this->useragent,"amaya"));
                $this->browsertype = "Amaya";
                $val = explode(" ", $val[1]);
                $this->version = $val[0];
            } else {
                $val = explode("/",$this->useragent);
                $this->browsertype = "Lynx";
                $this->version = $val[1];
            }
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * method to check for safari browser
     * @param void
     * @return bool true on success
     */
    function isSafari()
    {
        if(eregi("safari", $this->useragent))
        {
            $this->browsertype = "Safari";
            $this->version = "";
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /**
     * Various tests for Netscrape
     * @param void
     * @return bool true on success
     */
    function isNetscape()
    {
        if(eregi("netscape",$this->useragent))
        {
            $val = explode(" ",stristr($this->useragent,"netscape"));
            $val = explode("/",$val[0]);
            $this->browsertype = $val[0];
            $this->version = $val[1];
            return TRUE;
        }
        elseif(eregi("mozilla",$this->useragent) &&
                !eregi("rv:[0-9]\.[0-9]\.[0-9]",$this->useragent))
        {
            $val = explode(" ",stristr($this->useragent,"mozilla"));
            $val = explode("/",$val[0]);
            $this->browsertype = "Netscape";
            $this->version = $val[1];
            return TRUE;
        }
        else {
            return FALSE;
        }
    }//end func

    /**
     * Method to check for AOL connections
     * @param void
     * @return bool true on Success
     */
    function isAOL()
    {
        if (eregi("AOL", $this->useragent)){
            $var = stristr($this->useragent, "AOL");
            $var = explode(" ", $var);
            $this->aol = ereg_replace("[^0-9,.,a-z,A-Z]", "", $var[1]);
            return TRUE;
        }
        else {
            return FALSE;
        }
    }

    /* Soporte Chrome por Charles */
    function isChrome()
    {
    if(eregi("chrome", $this->useragent))
    {
    $this->browsertype = "Chrome";
    $val = stristr($this->useragent, "Chrome");
    $val = explode("/",$val);
    $val = explode(" ",$val[1]);
    $this->version = $val[0];
    return true;
    }
    else {
    return FALSE;
    }
    }

    /**
     * Method to tie them all up and output something useful
     * @param void
     * @return array
     */
    function whatBrowser()
    {
        $this->getBrowserOS();
        $this->isOpera();
        $this->isFirefox();
        $this->isKonqueror();
        $this->isIEv1();
        $this->isMSIE();
        $this->isGaleon();
        $this->isNetPositive();
        $this->isMSPIE();
        $this->isIcab();
        $this->isOmniWeb();
        $this->isPhoenix();
        $this->isFirebird();
        $this->isLynx();
        $this->isSafari();
        //$this->isMozAlphaBeta();
        //$this->isMozStable();
        //$this->isNetscape();
        $this->isAOL();
        $this->isChrome();
        return array('browsertype' => $this->browsertype,
                     'version' => $this->version,
                     'platform' => $this->platform,
                     'AOL' => $this->aol);
    }
}//end class
?>