ユーザーエージェントからブラウザ名、バージョン、OS名判別

/***判別側***/
//ブラウザ情報の取得
function browser_distinction($agent = '') {
if ($pos = strpos($agent, 'MSIE')) {
$browser_name = 'MSIE';
$browser_ver = substr($agent, $pos + 5, strpos($agent, ';', $pos) - $pos - 5);
} else if ($pos = strpos($agent, 'Firefox')) {
$browser_name = 'Firefox';
$browser_ver = substr($agent, $pos + 8, strlen($agent) - $pos - 8);
} else if ($pos = strpos($agent, 'Safari')) {
if ($pos = strpos($agent, 'Chrome')) {
$browser_name = 'Chrome';
$browser_ver = substr($agent, $pos + 7, strpos($agent, ' ', $pos) - $pos - 7);
} else {
$browser_name = 'Safari';
$pos = strpos($agent, 'Version');
$browser_ver = substr($agent, $pos + 8, strpos($agent, ' ', $pos) - $pos - 8);
}
} else if (ereg('Opera', $agent)) {
$browser_name = 'Opera';
$pos = strpos($agent, 'Version');
$browser_ver = substr($agent, $pos + 8, strlen($agent) - $pos - 8);
} else {
$browser_name = 'Unknown';
$browser_ver = 'Unknown';
}
return array($browser_name, $browser_ver);
}
//OS情報の取得
function os_distinction($agent = '') {
if (ereg('Windows NT 6.0', $agent)) {
$os_name = "Windows Vista";
} else if (ereg('Windows NT 5.1', $agent)) {
$os_name = "Windows XP";
} else if (ereg('Windows 98', $agent)) {
$os_name = "Windows 98";
} else if (ereg('Macintosh', $agent)) {
$os_name = "Macintosh";
} else if (ereg('Windows NT 6.1', $agent)) {
$os_name = "Windows 7";
} else if (ereg('Windows NT 6.1', $agent)) {
$os_name = "Windows 8";
}
return $os_name;
}

/***受け取り側***/

list($browser_name, $browser_ver) = browser_distinction($agent);

$os_name = os_distinction($agent)