[lwip-devel] [bug #53301] UDP Broadcast reception not interface-specific

[Michael Steinberg]

URL:
  <http://savannah.nongnu.org/bugs/?53301>

                 Summary: UDP Broadcast reception not interface-specific
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: michsteinb
            Submitted on: Thu 08 Mar 2018 08:28:30 AM UTC
                Category: UDP
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: 2.0.3

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Details:

Following setup (using RAW API):
2 Interfaces bound to IP1 and IP2 respectively.
2 UDP PCBs bound to IP1 and IP2 respectively (same port), but not "connected";
broadcast option set for both.

Outcome:
The PCB created last receives all broadcasts on the configured port, even
though they may have arrived on the interface with the matching IP of the
other PCB.

Depending on the design/specification this might be a bug or a limitation.

Possible relief:
Priorize PCBs bound to a specific IP address over ones bound to ipaddrany when
determining the destination PCB upon UDP broadcast reception and have them
match the configured interface address.




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