格式化http的header字符串爲數組

<?php
function http_header_to_arr($header_str){
	$header_list = explode("\n", $header_str);
	$header_arr = [];
	foreach ($header_list as $key => $value){
	    if(strpos($value, ':') === false){
	        continue;
	    }
	    list($header_key, $header_value) = explode(":", $value, 2);
	    $header_arr[$header_key] = trim($header_value);
	}
	if(isset($header_arr['Content-MD5'])){
		$header_arr['md5'] = bin2hex(base64_decode($header_arr['Content-MD5']));
	}
	return $header_arr;
}
?>