Re: Suggestion on perl handler to reject request with large content length

On Fri, Nov 19, 2010 at 9:59 AM, Mohit Anchlia <[email protected]> wrote:
> On Thu, Nov 18, 2010 at 6:26 PM, Mark J. Reed <[email protected]> wrote:
>> On Thu, Nov 18, 2010 at 8:47 PM, Mohit Anchlia <[email protected]> wrote:
>>> I have a requirement to look at content length and if it is greatar
>>> than desired size then return error message. So psuedo code is like:
>>
>> Easier solution: use LImitRequestBody, but have a perl handler that
>> sets a custom response text for  413's as appropriate.
> Problem is that LimitRequestBody is not returning 413. Not sure why.
> If at all I get LimitRequesTBody to work then how will I bind this
> handler to the status code?
>>
>> something like:
>>
>> sub handler {
>>    my $r = shift;
>>    if ($r->uri =~ /abc/) {
>>
>>    $r->custom_response
>>
>> What if the request has no Content-Length: header at all?  Do you let
>> it through then, no matter how big the body is?
>>
>>
>>> if content_length > 32G
>>> then
>>>  if url contains /abc/
>>>  then
>>>      echo "0|abc|Bad length" # pipe delimited format that some
>>> clients api support
>>>  else if url contains /def/
>>>      echo "<xml><message>Bad request</message><xml>" # client supporting XML
>>>  fi
>>> fi
>>
>> Yuck.  I would move the logic into whatever handles the API calls
>> rather than duplicating the mapping from URI's to code in two places.
>> That's just asking for things to get out of synch.
>
> I agree, but only problem is that the handler is in Jboss App. which
> means streams will have to pass from web server to our app server. I
> was trying to see if we can block right at the web server.
>>
>>> I first thought of using LimitRequestBody but that didn't work for me.
>>> So now I am thinking if using perl handlers.
>>>
>>> P.S. Note: Our requests are mod-jk requests. So if content length
>>> check succeeds then hand over the request to mod jk workers wihch then
>>> send it to jboss app server.
>>>
>>> I tried to write code but still unsure of few thing:
>>>
>>> 1. If I return  HTTP_REQUEST_ENTITY_TOO_LARGE response then would it
>>> still continue sending the request to mod_jk. Or would it be returned
>>> back to the client? When does apache decide if request need to be
>>> stopped and send back to the client.
>>> 2. Does my code look ok and something that will work? Can someone
>>> please suggest?
>>>
>>>
>>> This is my sample code
>>>
>>> sub content_handler {
>>>  my $r = shift;
>>>  my $uri = $r->uri;
>>>  if ( $r->header_in("Content-length") lt 20000000) {
>>>      return Apache2::Const::OK; # Continue sending request to mod jk worker
>>>  }
>>>  $r->send_http_header;
>>>  if ($uri =~ /xml/){
>>>     $r->content_type("text/xml");
>>>     $r->print("File too large|Bye"); #Send pipe delimited back to the
>>> client assuming it will not continue sending this request to mod_jk
>>> worker
>>>  }else{
>>>     $r->content_type("text/plain");
>>>     $r->print ("<xml><Message>Too Large, Bye!!</Message></xml>");
>>> #Send xml delimited back to the client assuming it will not continue
>>> sending this request to mod_jk worker
>>>  }
>>>
>>>  return Apache2::Const::HTTP_REQUEST_ENTITY_TOO_LARGE; # Return back to client

I still need some suggestion on this question:

If I return  HTTP_REQUEST_ENTITY_TOO_LARGE response then would PerlHandler
still continue sending the request to mod_jk. Or would it be returned
back to the client? When does apache decide if request need to be
stopped and send back to the client.

>>>
>>
>>
>>
>> --
>> Mark J. Reed <[email protected]>
>>
>