[fpc-pascal] How to handle External:SIGPIPE on linux

waldo kitty wkitty42 at windstream.net
Fri May 31 17:46:46 CEST 2013

On 5/31/2013 07:31, Dennis wrote:
> I am using LNet 's SSL sockets on ubuntu.
> When I use a self signed certificate and the browser gets a warning, it seems
> the browser immediately send a close-notify or shutdown ssl signal to the server
> and then without waiting close the connection.

sadly, this is common practice... in a firewall product i work with, we called 
the traffic afterward a "spurious firewall hit" because the firewall logged the 
traffic which came after the connection was already terminated... most of the 
time, this traffic was termination acknowledgment...

this problem can originate in the other direction as well... the server may 
close the connection without waiting on the client to acknowledge... both cases 
can be problematic (eg: "spurious firewall hit")

> On my server side (written with Lnet  SSL), it did not know the connection was
> closed already and still thinking of handling the close-notify + shutdown tries
> to shutdown the SSL on its side and then encounter the serious PIPE error (which
> I guess it tries to send acknowledge of the close-notify/shutdown back to the
> browser) when the pip is already closed.  I guess Lnet SSL implementation is not
> aware that the other side can close the connection without waiting for its
> acknowledgement.

sounds like it...

> This external SIGPIPE immediately crash the program even though the original
> Lnet codes has a try except block.
> Is there something I can do to trap this external SIGPIPE?
> (I tried emaillng the author but no response for weeks).

i have no idea... i only wanted to provide confirmation of the practice as 
mentioned above...

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