[lwip-devel] [bug #2595] loopif results in NULL reference for incoming TCP packets

[Tai-hwa Liang]

Follow-up Comment #18, bug #2595 (project lwip):

Sorry for the interruption.  I'm the original poster of the thread "local
connection failed on loopif, race?" as mentioned in comment#7.  I have done a
couple of tests with loopif plus RAW API based client/server on two different
platforms(FreeRTOS and unixsim running on FreeBSD).

It's interesting to note that with the current sys_timeout() based
implementation, the client hung after sending the first string after
connected to the server(for debugging traces, see
http://lists.gnu.org/archive/html/lwip-users/2007-03/msg00131.html ).

The attached patches(loopif-q[2].patch) are the thread/mbox based
implementation(with slightly modifications) which passed the test described
in aforementioned environment. Since slipif, pppif or even ethernetif in many
cases would have its own thread to process I/O requests, I think it's
reasonable for loopif to put the packet I/O to a different thread context. 
The downside is that the patch didn't try to address NO_SYS, yet.

In addition to that, it looks to me that the loopback can be something other
than 127/8 as there doesn't appear to be any restriction on this inside the
stack.

(file #12510, file #12511)
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Additional Item Attachment:

File name: loopif-q.patch                 Size:3 KB
File name: loopif-q2.patch                Size:3 KB


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