//输出安全的html
function h($text, $tags = null){
$text = trim($text);
//完全过滤注释
$text = preg_replace('/<!--?.*-->/','',$text);
//完全过滤动态代码
$text = preg_replace('/<\?|\?'.'>/','',$text);
//完全过滤js
$text = preg_replace('/<script?.*\/script>/','',$text);
$text = str_replace('[','[',$text);
$text = str_replace(']',']',$text);
$text = str_replace('|','|',$text);
//过滤换行符
$text = preg_replace('/\r?\n/','',$text);
//br
$text = preg_replace('/<br(\s\/)?'.'>/i','[br]',$text);
$text = preg_replace('/(\[br\]\s*){10,}/i','[br]',$text);
//过滤危险的属性,如:过滤on事件lang js
while(preg_match('/(<[^><]+)( lang|on|action|background|codebase|dynsrc|lowsrc)[^><]+/i',$text,$mat)){
$text=str_replace($mat[0],$mat[1],$text);
}
while(preg_match('/(<[^><]+)(window\.|javascript:|js:|about:|file:|document\.|vbs:|cookie)([^><]*)/i',$text,$mat)){
$text=str_replace($mat[0],$mat[1].$mat[3],$text);
}
if(empty($tags)) {
$tags = 'table|td|th|tr|i|b|u|strong|img|p|br|div|strong|em|ul|ol|li|dl|dd|dt|a';
}
//允许的HTML标签
$text = preg_replace('/<('.$tags.')( [^><\[\]]*)>/i','[\1\2]',$text);
//过滤多余html
$text = preg_replace('/<\/?(html|head|meta|link|base|basefont|body|bgsound|title|style|script|form|iframe|frame|frameset|applet|id|ilayer|layer|name|script|style|xml)[^><]*>/i','',$text);
//过滤合法的html标签
while(preg_match('/<([a-z]+)[^><\[\]]*>[^><]*<\/\1>/i',$text,$mat)){
$text=str_replace($mat[0],str_replace('>',']',str_replace('<','[',$mat[0])),$text);
}
//转换引号
while(preg_match('/(\[[^\[\]]*=\s*)(\"|\')([^\2=\[\]]+)\2([^\[\]]*\])/i',$text,$mat)){
$text=str_replace($mat[0],$mat[1].'|'.$mat[3].'|'.$mat[4],$text);
}
//过滤错误的单个引号
while(preg_match('/\[[^\[\]]*(\"|\')[^\[\]]*\]/i',$text,$mat)){
$text=str_replace($mat[0],str_replace($mat[1],'',$mat[0]),$text);
}
//转换其它所有不合法的 < >
$text = str_replace('<','<',$text);
$text = str_replace('>','>',$text);
$text = str_replace('"','"',$text);
//反转换
$text = str_replace('[','<',$text);
$text = str_replace(']','>',$text);
$text = str_replace('|','"',$text);
//过滤多余空格
$text = str_replace(' ',' ',$text);
return $text;
}