Re: [B.A.T.M.A.N.] [PATCH v2] alfred: Request MAC resolution for IPv4 address not in ARP cache

On Mittwoch, 24. Oktober 2018 13:21:28 CEST Jonathan Haws wrote: [...]

•   while (retries-- && !(arpreq.arp_flags & ATF_COM)) {
  

•           ipv4_request_mac_resolve(addr);
  

•           usleep(200000);
  

•           if (ioctl(interface->netsock, SIOCGARP, &arpreq) < 0)
  

•                   return -1;
  

•   }
  

•   if (arpreq.arp_flags & ATF_COM) {
            memcpy(mac, arpreq.arp_ha.sa_data, sizeof(*mac));
    } else {
  

According to gary [1], this doesn't work because the ioctl fails for him and then the function returns immediately (before the while loop).

Please adjust your patch - but please don't use his code - it looks rather ugly and also doesn't work for multiple retries. You most likely want to drop the if-ioctl completely and then put everything in your while loop:

while (ioctl(interface->netsock, SIOCGARP, &arpreq) < 0 || !(arpreq.arp_flags & ATF_COM)) { if (retries-- <= 0) break;

ipv4_request_mac_resolve(addr); usleep(200000); }

But feel to propose a different (cleaner) approach.

Kind regards, Sven

[1] https://lists.open-mesh.org/pipermail/b.a.t.m.a.n/2018-October/018195.html