Nginx判断UserAgent添加referer

server {
  listen       80;
  server_name ~^(.+)$;
  location / {
      set $var "";
      set $ua  "";
      if ($http_user_agent ~* ".*Google") {
         set $var  "abc.com";
         set $ua   "PlayStation";
      }
      if ($http_referer) {
         set $var $http_referer;
      }
      if ($http_user_agent !~* ".*Google") {
         set $ua   $http_user_agent;
      }
      proxy_set_header Referer $var;
      proxy_set_header User-Agent $ua;
      proxy_pass http://xxx;
      proxy_buffering off;
      proxy_http_version 1.1;
      access_log /var/log/nginx/upstream.log;
      add_header Cache-Control "public, max-age=604800";
      add_header Last-Modified "Thu, 04 Mar 2021 03:32:34 GMT";
      add_header ETag "60121c24-264";
  }
}