Re: [libmicrohttpd] integration with my websockets

[Christian Grothoff]

Jose,

Have you considered doing

  if upgrade-requested-for(req) then
     my_cls = create-websocket-for(req)
     if my_cls created then
          MHD_create_response_for_upgrade (&my_handler, my_cls);
     else
          reply "internal error"
     end
  else
     ....
  end

Basically, use the "upgrade_handler_cls" argument to pass along any kind
of state you need for your upgrade handling.  That way, you
can do pretty much any initialization/setup work you require before you
queue the response object and thus lock yourself into some particular
type of response.

As far as I see it, the only limitation here is that you cannot touch
the socket itself. (However, technically you can touch it as well using
MHD_CONNECTION_INFO_CONNECTION_FD for HTTP-only connections, but it's
usually not a good idea to hack around with that.)


Happy hacking!

-Christian

On 04/11/2017 07:23 PM, José Bollo wrote:
>> Could you explain a bit more do you want to implement and why it is
>> not possible?
> 
> This pseudo-code is no more possible:
> 
>   if upgrade-requested-for(req) then
>      handler = create-websocket-for(req)
>      if handler created then
>           reply "switch protocol"
>      else
>           reply "internal error"
>      end
>   else
>      ....
>   end
> 
> Instead you may write:
> 
>   if upgrade-requested-for(req) then
>      reply "switch protocol" with callback
>   else
>      ....
>   end
> 
> and in the callback
> 
>   handler = create-websocket-for(req)
>   if handler created then
>       cool
>   else
>       not cool, too late for sending an internal error
>   end
> 
> But as written there is something not cool cool
> So the following version is dandling with the hole
> 
>   if upgrade-requested-for(req) then
>      handler = create-websocket-lazy
>      if handler created then
>           reply "switch protocol" with callback
>      else
>           reply "internal error"
>      end
>   else
>      ....
>   end
> 
> and in the callback
> 
>   attach-websocket-socket(...)
> 
>>
>>>> Third, do you plan to provide a new version soon?  
>>
>> Yes, watch this list. :)
>>
> 
>

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