[fpc-pascal] CustHttpApp again, error: "Missing HTTP protocol version in request"

[Michael Van Canneyt]

On Fri, 25 Apr 2014, silvioprog wrote:

> 2014-04-25 10:24 GMT-03:00 Michael Van Canneyt <michael at freepascal.org>:
>       On Fri, 25 Apr 2014, silvioprog wrote:
>             2014-04-25 3:39 GMT-03:00 Michael Van Canneyt <michael at freepascal.org>:
>             [...] 
>                   Damn windows returning 0 on read... Can you please test with the following change:
>
>                      Procedure FillBuffer;
>
>                      Var
>                        R : Integer;
>
>                      begin
>                        SetLength(FBuffer,ReadBufLen);
>                  Repeat
>                    r:=FSocket.Read(FBuffer[1],ReadBufLen);
>                    If r<0 then
>                      Raise EHTTPServer.Create(SErrReadingSocket);
>                    if R=0 then
>                      Sleep(10);
>                  Until (R<>0);
>                  if (R<ReadBuflen) then
>                    SetLength(FBuffer,r);
>                end;
> 
>
>             After apply this change, now when read returns 0, it freezes the app., because the "sleep(10)" command is infinitely called. :/
> 
> 
> OK, what we can do is add a timeout:
> 
> Procedure FillBuffer;
> 
> Const
>   MaxReadRetries = 150;
> 
> Var
>   R,C : Integer;
> 
> begin
>   C:=0;
>   SetLength(FBuffer,ReadBufLen);
>   Repeat
>     r:=FSocket.Read(FBuffer[1],ReadBufLen);
>     If r<0 then
>       Raise EHTTPServer.Create(SErrReadingSocket);
>     if R=0 then
>       begin
>       Sleep(10);
>       Inc(C);
>       end;
>   Until (R<>0) or (C>MaxReadRetries);
>   if (R<ReadBuflen) then
>     SetLength(FBuffer,r);
> end;
> 
> It will then try 150 times, and then error out.
> 
> BUT, reading this:
> 
> http://msdn.microsoft.com/en-us/library/windows/desktop/ms740121%28v=vs.85%29.aspx
> 
> "If the connection has been gracefully closed, the return value is zero."
> 
> So, this means then thay the original implementation is correct. You just need to catch the error using the OnRequestError handler...
> 
> 
> Sorry for my ignorance, but, would not it be better to read the HTTP data only if the client is still connected or if read bytes > 0?

Yes and no. 
Yes in the sense that you have a more 'clean' experience.
No, because it IS an error condition (client went away unexpectedly) and you should be aware of it.

I will make it a property that is settable: 'IgnoreLostConnections' or so.

Michael.