[ECOS] Re: Disable IPv6 at startup?

[Grant Edwards <grant dot b dot edwards at gmail dot com>]

On 2012-02-29, Grant Edwards <grant.b.edwards@gmail.com> wrote:
> On 2012-02-16, Grant Edwards <grant.b.edwards@gmail.com> wrote:
>
>> What's the simplest/best way to "disable" IPv6 at runtime?
>
> Here's my first try at disabling ipv6 at runtime.
>
> It seems to work well enough, but it's not as clean as I had hoped.
> Could a patch using this approach be accepted?
>
> Of course I'd clean up the formatting, add a changelog entry and so
> on.  I'd also be happy to make this something that has to be enabled
> via CDL -- though with the changes shown below, the stack behaves
> exactly as before by default. I'm not keen on the "add a globally
> visible flag" approach, but it seemed like the only simple solution.
>
> The three things I'm trying to disable are all called via init-table
> entries, and AFAICT there's no practical way to remove/skip a table
> entry at runtime.
>
> The declaration and definition of the globally visible
> cyg_ipv6_runtime_disable flag probably belong somewhere else, but I
> haven't figured out where.

OK, I've come up with something I like a little better.  The only
change it requires to the network stack is that ip6_init2() needs to
be globally visible (ip6_init already is, so I don't see the harm in
making ip6_init2 visible).  If ip6_init2 is visible, then you can
disable ipv6 support with this code:

static void init_noop(void* dummy)
{
}

static void disable_ipv6(void)
{
  extern void cyg_net_add_domain(void *);
  extern void ip6_init2(void *);
  extern char inet6domain[];
  extern struct init_tab_entry __NET_INIT_TAB__[], __NET_INIT_TAB_END__;
  struct init_tab_entry *init_entry;

  for (init_entry = __NET_INIT_TAB__; init_entry != &__NET_INIT_TAB_END__;  init_entry++) 
      if ((init_entry->fun == cyg_net_add_domain && init_entry->data == (void*)inet6domain) ||
          (init_entry->fun == ip6_init2))
          init_entry->fun = init_noop;
}

-- 
Grant Edwards               grant.b.edwards        Yow! I want a WESSON OIL
                                  at               lease!!
                              gmail.com            


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