[lwip-devel] [bug #56281] arp header process modify back to previous version in etharp_input

[Simon Kószó]

URL:
  <https://savannah.nongnu.org/bugs/?56281>

                 Summary: arp header process modify back to previous version
in etharp_input
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: koszsim
            Submitted on: Tue 07 May 2019 10:56:54 AM UTC
                Category: ARP
                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:

I just wanted to tell how I "fixed" the receiveing of ARP packet in my
application. I am quiet starter with lwIP so probably I did something badly
when I called etharp_input(). Does anybody can help me to figure out the
reason?

I upgraded lwIP from 1.4.1 to 2.0.3. When I finally could build the code and
download the program to the target I noticed that it does not respond to ping
command. Having debugged the program and compared the code with 1.4.1, I could
fix the problem with modifying the code in etharp_input function:

I wrote this statement in line 650 in src/core/ipv4/etharp.c: 
hdr = (struct etharp_hdr *)((u8_t*)p->payload + SIZEOF_ETH_HDR);
instead of this statement:
hdr = (struct etharp_hdr *)p->payload;

Now my program works well in my target.

Thank you if someone try to figure out the possible reason.





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