PHP gets search engine keywords

//获取来自搜索引擎入站时的关键词 
function get_keyword($url,$kw_start) 
{ 
$start=stripos($url,$kw_start); 
$url=substr($url,$start+strlen($kw_start)); 
$start=stripos($url,'&'); 
if ($start>0) 
{ 
$start=stripos($url,'&'); 
$s_s_keyword=substr($url,0,$start); 
} 
else 
{ 
$s_s_keyword=substr($url,0); 
} 
return $s_s_keyword; 
} 
 
$url=isset($_SERVER['HTTP_REFERER'])?$_SERVER['HTTP_REFERER']:'';//获取入站url。 
$search_1="google.com"; //q= utf8 
$search_2="baidu.com"; //wd= gbk 
$search_3="yahoo.cn"; //q= utf8 
$search_4="sogou.com"; //query= gbk 
$search_5="soso.com"; //w= gbk 
$search_6="bing.com"; //q= utf8 
$search_7="youdao.com"; //q= utf8 
 
$google=preg_match("/\b{$search_1}\b/",$url);//记录匹配情况，用于入站判断。 
$baidu=preg_match("/\b{$search_2}\b/",$url); 
$yahoo=preg_match("/\b{$search_3}\b/",$url); 
$sogou=preg_match("/\b{$search_4}\b/",$url); 
$soso=preg_match("/\b{$search_5}\b/",$url); 
$bing=preg_match("/\b{$search_6}\b/",$url); 
$youdao=preg_match("/\b{$search_7}\b/",$url); 
$s_s_keyword=""; 
$bul=$_SERVER['HTTP_REFERER']; 
//获取没参数域名 
preg_match('@^(?:http://)?([^/]+)@i',$bul,$matches); 
$burl=$matches[1]; 
//匹配域名设置 
$curl="www.netxu.com"; 
if($burl!=$curl){ 
if ($google) 
{//来自google 
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。 
$s_s_keyword=urldecode($s_s_keyword); 
$urlname="谷歌："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
} 
else if($baidu) 
{//来自百度 
$s_s_keyword=get_keyword($url,'wd=');//关键词前的字符为"wd="。 
$s_s_keyword=urldecode($s_s_keyword); 
$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
$urlname="百度："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
else if($yahoo) 
{//来自雅虎 
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。 
$s_s_keyword=urldecode($s_s_keyword); 
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
$urlname="雅虎："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
else if($sogou) 
{//来自搜狗 
$s_s_keyword=get_keyword($url,'query=');//关键词前的字符为"query="。 
$s_s_keyword=urldecode($s_s_keyword); 
$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
$urlname="搜狗："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
else if($soso) 
{//来自搜搜 
$s_s_keyword=get_keyword($url,'w=');//关键词前的字符为"w="。 
$s_s_keyword=urldecode($s_s_keyword); 
$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
$urlname="搜搜："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
else if($bing) 
{//来自必应 
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。 
$s_s_keyword=urldecode($s_s_keyword); 
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
$urlname="必应："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
else if($youdao) 
{//来自有道 
$s_s_keyword=get_keyword($url,'q=');//关键词前的字符为"q="。 
$s_s_keyword=urldecode($s_s_keyword); 
//$s_s_keyword=iconv("GBK","UTF-8",$s_s_keyword);//引擎为gbk 
$urlname="有道："; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
else{ 
$urlname=$burl; 
$s_s_keyword=""; 
$_SESSION["urlname"]=$urlname; 
$_SESSION["s_s_keyword"]=$s_s_keyword; 
} 
$s_urlname=$urlname; 
$s_urlkey=$s_s_keyword; 
} 
else{ 
$s_urlname=$_SESSION["urlname"]; 
$s_urlkey=$_SESSION["s_s_keyword"]; 
}