`ifconfig` patch to resolve IPv6 scope names

[Stefan Esser]

Am 11.08.17 um 11:58 schrieb Andrey V. Elsukov:
> On 10.08.2017 23:02, raichoo via freebsd-hackers wrote:
>> Oh boy, should have read more code before posting that ^^.
>>
>> Thanks a lot for your feedback :)
>>
>> I've modified that patch to make it use the macros defined in in6.h. I'm
>> also quite
>> aware that this patch might be rejected since it might break script
>> depending on `ifconfig`
>> output. But it's a useful little learning experience anyway :)
>>
>> Kind regards,
>> raichoo
>>
>> Here's the new iteration:
>>
>> diff --git a/sbin/ifconfig/af_inet6.c b/sbin/ifconfig/af_inet6.c
>> index e93d94355e..e1d44395c9 100644
>> --- a/sbin/ifconfig/af_inet6.c
>> +++ b/sbin/ifconfig/af_inet6.c
>> @@ -167,6 +167,35 @@ setip6eui64(const char *cmd, int dummy __unused, int s,
>>  }
>>
>>  static void
>> +in6_addr_scope(const struct in6_addr *addr)
>> +{
>> +    if (IN6_IS_ADDR_LINKLOCAL(addr))
>> +        printf("link-local ");
>> +    else if (IN6_IS_ADDR_SITELOCAL(addr))
>> +        printf("site-local ");
>> +    else if (IN6_IS_ADDR_MULTICAST(addr)) {
>> +        printf("multicast ");
>> +        switch (__IPV6_ADDR_MC_SCOPE(addr)) {
>> +        case __IPV6_ADDR_SCOPE_NODELOCAL:
>> +            printf("node-local ");
>> +            break;
>> +        case __IPV6_ADDR_SCOPE_LINKLOCAL:
>> +            printf("link-local ");
>> +            break;
>> +        case __IPV6_ADDR_SCOPE_SITELOCAL:
>> +            printf("site-local ");
>> +            break;
>> +        case __IPV6_ADDR_SCOPE_ORGLOCAL:
>> +            printf("organization-local ");
>> +            break;
>> +        case __IPV6_ADDR_SCOPE_GLOBAL:
>> +            printf("global ");
>> +            break;
>> +        }
>> +    }
>> +}
> 
> Hi,
> 
> I'm not sure how it is useful configuring multicast addresses on the
> interface. I think there are only four possible useful cases:
> 1. loopback address should be marked as link-local
> 2. link-local addresses should be marked as link-local
> 3. site-local addresses should be marked as site-local
> 4. all other non multicast addresses should be marked as global
> 
> Also, AFAIR, the site-local scope was deprecated a long time ago.

Yes, but I think printing this extra information is still useful, at
least for an less experienced user who does not have memorized the
different scope types.

It doesn't matter, if a (possible) configuration makes sense, this
patch just reports what's already configured ...

If a site-local address is in use, it will be immediately obvious,
and thus it makes sense to include it in the scope list, even if it
should never be reported ;-)

I'd like to see this patch committed ...

Regards, STefan