'Expect' HTTP Header

[Jason Fister <ja...@gmail.com>]

Hello folks,
According to HTTP 1.1 spec, if a client sends a Expect: 100-continue header
with a request, the server can inspect the header and reply with a HTTP
status 100 Continue if its ready to accept the data. The client after
receiving the 100 request will send the request body. The server is also
allowed to send a final http status msg and close the connection after
inspecting the headers if it doesn't want to accept the request body.

I am trying to implement this in my apache module but am a little confused
as to how to do this. Here is a section of the code:

static int my_handler(request_rec* req)
{
   .....
   .....
   .....
   bool sta = ShouldSrvrRespondWith100(req);
   if (tru==sta)
   {
     req->status = HTTP_CONTINUE;
     return OK;
   }
   else
   {
     ProcessRequest(req);
   }
}

The function 'ShouldSrvrRespondWith100' is defined as

bool ShouldSrvrRespondWith100(request_rec* req)
{
  if((HTTP ver is 1.1) && ('Expect' HTTP header is set))
  {
    return true;
  }
  else
  {
    return false;
  }
}


Am I doing this correctly? What is don't understand is I want to resume
execution of the code from where I left off before I sent the 100 http
status to the client - how do I achieve that?

in the request_rec structure, there is a field called 'expecting_100' should
I be checking this value in the request to see if this particular request is
in response to a 100 continue from the server?

Thanks!
Jason

Re: 'Expect' HTTP Header

[Jason Fister <ja...@gmail.com>]

Thanks for your response.

>
>
> AIUI: In your handler, you ask the input filters for the body.  If the
> client is expecting 100-continue, the HTTP input filter takes care of
> responding to it.
>


I use

ap_setup_client_block
ap_should_client_block(req)
ap_get_client_block

to get the request body.

But before I get to that stage, I want to process the HTTP headers to see if
I want to continue accepting the rest of the request. If yes, I want to
respond with a 100 Continue status. Will apache automatically send 100
Continue response to the client as soon as I set req->status =
HTTP_CONTINUE, wait and resume processing when the client starts sending the
rest of the request?



>
> see ap_http_filter() in modules/http/http_filters.c
>
> You could probably short-circuit the regular processing (but not in an
> API friendly way).
>

I will take a look at the file that you have mentioned.

Thanks again.



>
>
> --
> Eric Covener
> covener@gmail.com
>

Re: 'Expect' HTTP Header

[Eric Covener <co...@gmail.com>]

On Thu, Sep 18, 2008 at 3:35 PM, Jason Fister <ja...@gmail.com> wrote:
> Can anyone point me in the right direction? I have searched on the web
> extensively but I did not find anything helpful.

AIUI: In your handler, you ask the input filters for the body.  If the
client is expecting 100-continue, the HTTP input filter takes care of
responding to it.

see ap_http_filter() in modules/http/http_filters.c

You could probably short-circuit the regular processing (but not in an
API friendly way).


-- 
Eric Covener
covener@gmail.com

Re: 'Expect' HTTP Header

[Jason Fister <ja...@gmail.com>]

Can anyone point me in the right direction? I have searched on the web
extensively but I did not find anything helpful.

On Wed, Sep 17, 2008 at 2:49 PM, Jason Fister <ja...@gmail.com> wrote:

> Hello folks,
> According to HTTP 1.1 spec, if a client sends a Expect: 100-continue header
> with a request, the server can inspect the header and reply with a HTTP
> status 100 Continue if its ready to accept the data. The client after
> receiving the 100 request will send the request body. The server is also
> allowed to send a final http status msg and close the connection after
> inspecting the headers if it doesn't want to accept the request body.
>
> I am trying to implement this in my apache module but am a little confused
> as to how to do this. Here is a section of the code:
>
> static int my_handler(request_rec* req)
> {
>    .....
>    .....
>    .....
>    bool sta = ShouldSrvrRespondWith100(req);
>    if (tru==sta)
>    {
>      req->status = HTTP_CONTINUE;
>      return OK;
>    }
>    else
>    {
>      ProcessRequest(req);
>    }
> }
>
> The function 'ShouldSrvrRespondWith100' is defined as
>
> bool ShouldSrvrRespondWith100(request_rec* req)
> {
>   if((HTTP ver is 1.1) && ('Expect' HTTP header is set))
>   {
>     return true;
>   }
>   else
>   {
>     return false;
>   }
> }
>
>
> Am I doing this correctly? What is don't understand is I want to resume
> execution of the code from where I left off before I sent the 100 http
> status to the client - how do I achieve that?
>
> in the request_rec structure, there is a field called 'expecting_100'
> should I be checking this value in the request to see if this particular
> request is in response to a 100 continue from the server?
>
> Thanks!
> Jason
>