[lwip-devel] [bug #59319] ICMPv6 neighbor solicitation fails if LWIP_IPV6_MLD is set

[Erik Ekman]

Follow-up Comment #1, bug #59319 (project lwip):

I agree that this seems strange.

Originally the code was like this (commit 4bfbe7ebe):


  /* match packet against an interface, i.e. is this packet for us? */
  if (ip6_addr_ismulticast(ip6_current_dest_addr())) {
    /* Always joined to multicast if-local and link-local all-nodes group. */
    if (ip6_addr_isallnodes_iflocal(ip6_current_dest_addr()) ||
        ip6_addr_isallnodes_linklocal(ip6_current_dest_addr())) {
      netif = inp;
    }
#if LWIP_IPV6_MLD
    else if (mld6_lookfor_group(inp, ip6_current_dest_addr())) {
      netif = inp;
    }
#else /* LWIP_IPV6_MLD */
    else if (ip6_addr_issolicitednode(ip6_current_dest_addr())) {
      /* Accept all solicited node packets when MLD is not enabled
       * (for Neighbor discovery). */
      netif = inp;
    }
#endif /* LWIP_IPV6_MLD */
    else {
      netif = NULL;



Then in commit 6e81f722a the solicited node handling was added:


#else /* LWIP_IPV6_MLD */
    else if (ip6_addr_issolicitednode(ip6_current_dest_addr())) {
      /* Filter solicited node packets when MLD is not enabled
       * (for Neighbor discovery). */
      netif = NULL;
      for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
        if (ip6_addr_isvalid(netif_ip6_addr_state(inp, i)) &&
            ip6_addr_cmp_solicitednode(ip6_current_dest_addr(),
netif_ip6_addr(inp, i))) {
          netif = inp;
          LWIP_DEBUGF(IP6_DEBUG, ("ip6_input: solicited node packet accepted
on interface %c%c\n",
              netif->name[0], netif->name[1]));
          break;
        }
      }
    }
#endif /* LWIP_IPV6_MLD */


Since solicited nodes are not checked inside mld6 code, it seems this code
should always be active.

Simon, do you have an opinion here?

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