php 该如何获取从百度搜索进入网站的关键词

<?php

function search_word_from() {
$referer = isset($_SERVER['HTTP_REFERER'])?$_SERVER['HTTP_REFERER']:'';
if(strstr( $referer, 'baidu.com')){ //百度
preg_match( "|baidu.+wo?r?d=([^\\&]*)|is", $referer, $tmp );
$keyword = urldecode( $tmp[1] );
$from = 'baidu'; （PS：T不错的PHP Q扣峮：276167802，验证：csl）
}elseif(strstr( $referer, 'google.com') or strstr( $referer, 'google.cn')){ //谷歌
preg_match( "|google.+q=([^\\&]*)|is", $referer, $tmp );
$keyword = urldecode( $tmp[1] );
$from = 'google';
}elseif(strstr( $referer, 'so.com')){ //360搜索
preg_match( "|so.+q=([^\\&]*)|is", $referer, $tmp );
$keyword = urldecode( $tmp[1] );
$from = '360';
}elseif(strstr( $referer, 'sogou.com')){ //搜狗
preg_match( "|sogou.com.+query=([^\\&]*)|is", $referer, $tmp );
$keyword = urldecode( $tmp[1] );
$from = 'sogou';
}elseif(strstr( $referer, 'soso.com')){ //搜搜
preg_match( "|soso.com.+w=([^\\&]*)|is", $referer, $tmp );
$keyword = urldecode( $tmp[1] );
$from = 'soso';
}else {
$keyword ='';
$from = '';
}

return array('keyword'=>$keyword,'from'=>$from);
}

//以下为测试
//在搜索引擎搜索个关键词，进入网站
$word = search_word_from();
if(!empty($word['keyword'])){
echo '关键字：'.$word['keyword'].' 来自：'.$word['from'];
}
?>