[lwip-devel] [bug #43739] Accept not reporting errors about aborted connections

[Joel Cunningham]

URL:
  <http://savannah.nongnu.org/bugs/?43739>

                 Summary: Accept not reporting errors about aborted
connections
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: jcunningham
            Submitted on: Tue 02 Dec 2014 05:18:26 PM GMT
                Category: sockets/netconn
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: 1.4.1

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Details:

I've discovered what appears to be a bug in accept's handling of aborted
connections due to exhaustion of netconns.

As per the Open group spec, I would expect an error to be returned when a new
connection fails the accept process:

http://pubs.opengroup.org/onlinepubs/009695399/functions/accept.html

I'm not sure if the correct return value should be ECONNABORTED or ENFILE (or
even ENOMEM)

In my particular case, the listener is establishing a new connection, but the
final step in tcp_process(), where the PCB is put into ESTABLISHED state,
TCP_EVENT_ACCEPT() is called and that returns ERR_ABRT because allocation of a
netconn failed (accept_function() returns ERR_MEM).  After that, the new
connection is aborted, but no error is reported on the listening
netconn/socket.

It looks like errors from within TCP are reported via the tcp_err callback,
but this would be hard to do in tcp_process() because there is no linkage
between the new connected PCB and the listener PCB.  This makes me think that
maybe the error should be reported in accept_function() where the allocation
failure happens.  Thoughts?




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