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Korjavin Ivan
Asked: 2014-02-23 22:58:54 +0800 CST

Redirect to 404 if filename passed as parameter does not exitsts

  • 772

I have special parameter data=/path/to/filename.htm in uri.

Its old and rusty site builded on SSI, and I can't modify it.

Problem is when filename passed as arg_data not exists, page is broken.

I want redirect to 404.htm in this case.

Something like that:

if (!-f $arg_data){
     rewrite ^.*$  /404.htm last;
   }

But I get:

rewrite or internal redirection cycle while processing "/404.htm

I think its because I didn't check if arg_data exists.

But nginx have not nested if-s.

I tried:

set $data index.htm;                                                                                                                                               
if ($args ~ "data=(.+)") {                                                                                                                                         
    set $data $1;                                                                                                                                                  
}                                                                                                                                                                                                                                                                                                                                          
if (!-f $data) {                                                                                                                                                
    rewrite ^.*$  /404.htm last;                                                                                                                                   
}

Idea was set $data to some file which 100% exists, and after that rewrite if data param is passed.

For some reason its give the same error, internal redirection cycle

Looks like I do it in wrong way.

nginx

2 Answers

  1. OK, this is a very strange scenario, and you seem to be on the right track.

    Instead of the rewrite, though, I would return 404; and use an error_page to define the 404 error page.

    For example:

    server {

    #...your other stuff...

    error_page 404 /404.htm;

    if (!-f $arg_data){
        return 404;
    }
}
    • 3
  2. Best Answer

    Ok, so regarding the last comments we had, you need an AND condition for two if statements.

    NGinx is not able to do this.

    To achieve this, we will use a little trick dealing with a $test var :

    server {

  #...directives...

  error_page 404 /404.htm;

  if ($args != "") {                  # Test if there are some args       
     set $test A;
  }

  if (!-f /full/path/to/$arg_data) {  # Test if file in args doesn't exist
     set $test "${test}B";
  }

  if ($test = AB) {       # If there are some args AND if file doesn't exist
     return 404;
  }

}
    • 2