[lxc-devel] [PATCH] hwaddr templating

[S.Çağlar Onur]

On Mon, Jan 6, 2014 at 11:46 AM, Serge Hallyn <serge.hallyn at ubuntu.com> wrote:
> Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
>> Quoting Guillaume ZITTA (lxc at zitta.fr):
>> > This change introduce mac address templating.
>> >
>> > By setting lxc.network.hwaddr to something like fe:xx:xx:xx:xx:xx
>> > each "x" will be replaced by a random value.
>> > If less significant bit of first byte is "templated", it will be
>> > set to 0.
>> >
>> > This chage introduce also a common randinit() function that could be
>> > used to initialize random generator.
>> >
>> > Signed-off-by: gza <lxc at zitta.fr>
>> > ---
>> >  doc/lxc.conf.sgml.in |  4 +++-
>> >  src/lxc/confile.c    | 36 ++++++++++++++++++++++++++++++++++--
>> >  src/lxc/utils.c      | 22 ++++++++++++++++++++++
>> >  src/lxc/utils.h      |  2 ++
>> >  4 files changed, 61 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/doc/lxc.conf.sgml.in b/doc/lxc.conf.sgml.in
>> > index e6d9689..4bbeeeb 100644
>> > --- a/doc/lxc.conf.sgml.in
>> > +++ b/doc/lxc.conf.sgml.in
>> > @@ -326,7 +326,9 @@ Foundation, Inc., 51 Franklin Street, Fifth
>> > Floor, Boston, MA 02110-1301 USA
>> >           the interface mac address is dynamically allocated by
>> >           default to the virtual interface, but in some cases,
>> >           this is needed to resolve a mac address conflict or to
>> > -         always have the same link-local ipv6 address
>> > +         always have the same link-local ipv6 address.
>> > +         Any "x" in address will be replaced by random value,
>> > +         this allows setting hwaddr templates.
>> >         </para>
>> >       </listitem>
>> >     </varlistentry>
>> > diff --git a/src/lxc/confile.c b/src/lxc/confile.c
>> > index 0982b3e..3d7554a 100644
>> > --- a/src/lxc/confile.c
>> > +++ b/src/lxc/confile.c
>> > @@ -508,6 +508,28 @@ static int macvlan_mode(int *valuep, const char
>> > *value)
>> >     return -1;
>> >  }
>> >
>> > +static int rand_complete_hwaddr(char *hwaddr)
>> > +{
>> > +   const char hex[] = "0123456789abcdef";
>> > +   char *curs = hwaddr;
>> > +
>> > +   randinit();
>> > +
>> > +   while (*curs != '\0')
>> > +   {
>> > +           if ( *curs == 'x' || *curs == 'X' ) {
>> > +                   if (curs - hwaddr == 1) {
>> > +                           //ensure address is unicast
>> > +                           *curs = hex[(rand() & 0x0E)];
>> > +                   } else {
>> > +                           *curs = hex[rand() & 0x0F];
>> > +                   }
>> > +           }
>> > +           curs++;
>> > +   }
>> > +   return 0;
>> > +}
>> > +
>> >  static int config_network_flags(const char *key, const char *value,
>> >                             struct lxc_conf *lxc_conf)
>> >  {
>> > @@ -575,11 +597,21 @@ static int config_network_hwaddr(const char
>> > *key, const char *value,
>> >  {
>> >     struct lxc_netdev *netdev;
>> >
>> > -   netdev = network_netdev(key, value, &lxc_conf->network);
>> > +   char *newval = strdup(value);
>>
>> Since this is strdup'd,
>>
>> > +
>> > +   rand_complete_hwaddr(newval);
>> > +
>> > +   netdev = network_netdev(key, newval, &lxc_conf->network);
>> >     if (!netdev)
>>
>> this error path needs to free it,
>>
>> >             return -1;
>> >
>> > -   return config_string_item(&netdev->hwaddr, value);
>> > +   if (!newval || strlen(newval) == 0) {
>> > +           netdev->hwaddr = NULL;
>>
>> as does this one in the case where newval != NULL.
>
> To be less terse: once you add this, it looks good, thanks.

Guillaume , could you please drop process_lock/process_unlock from the
patch while addressing Serge's comment as we no longer need them?

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-- 
S.Çağlar Onur <caglar at 10ur.org>