Nginx如何限制IP访问只允许特定域名访问

cd /usr/local/nginx/conf/

# 禁止ip访问
server {
    listen 80 default_server;
    listen 443 ssl default_server;
    server_name _;
    return 403;
}

server {
    listen       80;
    server_name  localhost;

    location / {
        root   html;
        index  index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   html;
    }
}

server {
    listen       80;
    server_name  xxx.com;

    location / {
        root   html;
        index  index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   html;
    }
}

./nginx -s reload