[lwip-devel] [bug #26062] FIN_WAIT_2 state following tcp_close should timeout eventually

[Jeff Barber]

Follow-up Comment #6, bug #26062 (project lwip):

I think this is actually a subtle API change that should be considered
carefully. 

Currently we have a tcp_close that acts like a shutdown(SHUT_WR) and we have
nothing that acts like close().  If you simply modify the timer handling,
we'll then have tcp_close acting like close(), but then we won't have a
shutdown(SHUT_WR).

As it stands now, a NO_SYS application can rely on receiving a final recv
callback with NULL pbuf argument indicating that the remote end sent a FIN. 
Some applications may be relying on this behavior for cleanup of application
state (mine does, for example).

IMO it would be preferable to have both a close and a shutdown as the two are
distinct and both have valid uses.  Naively, it seems like a simple flag would
be sufficient to distinguish the two cases but I could be overlooking many
details.

(Yes, I know that I originally filed this bug report but my understanding has
become more, er, nuanced since April. :-)


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