Nginx map regex with multiple variables to one variable

Question

Map variables to $clientIP with regex.

Webserver behind multiple CDN, The custom header with the client's real ip varies. So I came out with the follow expression.

#here I use @ as seperator
map "$http_cf_connecting_ip@$http_cdn_src_ip@$http_src_ip@$http_client_ip" $clientIP {

          "~[^-]+@-@-@-$"       $http_cf_connecting_ip;                 
          "~^-@[^-]+@-@-$"      $http_cdn_src_ip;        
          "~^-@-@[^-]+@-$"      $http_src_ip;             
          "~^-@-@-@[^-]+$"      $http_client_ip;
          "~^-@-@-@-$"          $remote_addr;
          default               $remote_addr;
}

I use postman to send custom http headers. But seems map will always go to default.

Richard Smith · Accepted Answer · 2019-08-29 12:33:50Z

1

The empty variables are probably just empty, rather than containing a literal hyphen. The access log uses a hyphen to indicate empty values.

You could rewrite your regular expressions to match the empty variables, or just use a named capture to match the first place containing a valid IP address.

For example:

map "$http_cf_connecting_ip@$http_cdn_src_ip@$http_src_ip@$http_client_ip" $clientIP {
    ~(^|@)(?<ipaddr>\d+\.\d+\.\d+\.\d+)($|@)    $ipaddr;
    default                                     $remote_addr;
}

answered Aug 29, 2019 at 12:33

Richard Smith

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1 Comment

wanfujinan Over a year ago

Totally right "The empty variables are probably just empty, rather than containing a literal hyphen",I am debugging the variables in access_log,thank you.

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