nginx中$host、$http_host 、$server_name 这三个变量有什么不同

Question

比如下面一段配置

if (!-e $request_filename) {
    rewrite /admin$ $scheme://$host$uri/ permanent;
    rewrite ^(/[^/]+)?(/sp-.*) $2 last;
    rewrite ^(/[^/]+)?(/.*\.php) $2 last;
}

why would $http_host be more dangerous?

Answer 1

$host的值有可能变化，先取请求头的host，如果没有去取接受请求的那个server的名称
$server_name表示接受请求的那个server的名称
至于$http_host，官方文档也没有这个值， 是不是题主写错了。 我只发现$http_name
下面贴上官方文档对着三个变量的定义：
$host
in this order of precedence: host name from the request line, or host name from the “Host” request header field, or the server name matching a request
$http_name
arbitrary request header field; the last part of a variable name is the field name converted to lower case with dashes replaced by underscores
$server_name
name of the server which accepted a request