[lxc-devel] [PATCH] hwaddr templating (with fixes from comments 2)

[Serge Hallyn]

nm, I've just hand-applied it, sorry for the noise.

Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
> Hi,
> 
> it seems thunderbird messed this patch up a bit.  Could you please
> send it to me privately as an attachment, or disable line wrap in
> thunderbird for the sake of this patch?
> 
> Otherwise I can hand-apply (reproduce it).
> 
> -serge
> 
> Quoting lxc at zitta.fr (lxc at zitta.fr):
> > 
> > Le 07/01/2014 01:07, Serge Hallyn a écrit :
> > > Quoting lxc at zitta.fr (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 change introduce also a common randinit() function that could be
> > >> used to initialize random generator.
> > >>
> > >> Signed-off-by: gza <lxc at zitta.fr>
> > > Sorry, two more changes needed.  If you prefer I can do them
> > > in-line.
> > >
> > Thanks, but it's a good C programming lesson for me.
> > 
> > Hope this is final patch rc1 time is comming ...
> > -------
> > 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    | 53
> > +++++++++++++++++++++++++++++++++++++++++++++++++---
> >  src/lxc/utils.c      | 22 ++++++++++++++++++++++
> >  src/lxc/utils.h      |  2 ++
> >  4 files changed, 77 insertions(+), 4 deletions(-)
> > 
> > diff --git a/doc/lxc.conf.sgml.in b/doc/lxc.conf.sgml.in
> > index 1350c63..e7adb2b 100644
> > --- a/doc/lxc.conf.sgml.in
> > +++ b/doc/lxc.conf.sgml.in
> > @@ -349,7 +349,9 @@ 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 d21fbec..595c423 100644
> > --- a/src/lxc/confile.c
> > +++ b/src/lxc/confile.c
> > @@ -510,6 +510,37 @@ 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;
> > +
> > +#ifndef HAVE_RAND_R
> > +    randseed(true);
> > +#else
> > +    unsigned int seed=randseed(false);
> > +#endif
> > +    while (*curs != '\0')
> > +    {
> > +        if ( *curs == 'x' || *curs == 'X' ) {
> > +            if (curs - hwaddr == 1) {
> > +                //ensure address is unicast
> > +#ifdef HAVE_RAND_R
> > +                *curs = hex[rand_r(&seed) & 0x0E];
> > +            } else {
> > +                *curs = hex[rand_r(&seed) & 0x0F];
> > +#else
> > +                *curs = hex[rand() & 0x0E];
> > +            } else {
> > +                *curs = hex[rand() & 0x0F];
> > +#endif
> > +            }
> > +        }
> > +        curs++;
> > +    }
> > +    return 0;
> > +}
> > +
> >  static int config_network_flags(const char *key, const char *value,
> >                  struct lxc_conf *lxc_conf)
> >  {
> > @@ -577,11 +608,27 @@ static int config_network_hwaddr(const char *key,
> > const char *value,
> >  {
> >      struct lxc_netdev *netdev;
> >  
> > -    netdev = network_netdev(key, value, &lxc_conf->network);
> > -    if (!netdev)
> > +    char *new_value = strdup(value);
> > +    if (!new_value) {
> > +        SYSERROR("failed to strdup '%s': %m", value);
> >          return -1;
> > +    }
> > +    rand_complete_hwaddr(new_value);
> >  
> > -    return config_string_item(&netdev->hwaddr, value);
> > +    netdev = network_netdev(key, new_value, &lxc_conf->network);
> > +    if (!netdev) {
> > +        free(new_value);
> > +        return -1;
> > +    };
> > +
> > +    if (!new_value || strlen(new_value) == 0) {
> > +        free(new_value);
> > +        netdev->hwaddr = NULL;
> > +        return 0;
> > +    }
> > +
> > +    netdev->hwaddr = new_value;
> > +    return 0;
> >  }
> >  
> >  static int config_network_vlan_id(const char *key, const char *value,
> > diff --git a/src/lxc/utils.c b/src/lxc/utils.c
> > index 3755bcd..c27af76 100644
> > --- a/src/lxc/utils.c
> > +++ b/src/lxc/utils.c
> > @@ -1084,3 +1084,25 @@ void **lxc_append_null_to_array(void **array,
> > size_t count)
> >      }
> >      return array;
> >  }
> > +
> > +int randseed(bool srand_it)
> > +{
> > +    /*
> > +    srand pre-seed function based on /dev/urandom
> > +    */
> > +    unsigned int seed=time(NULL)+getpid();
> > +
> > +    FILE *f;
> > +    f = fopen("/dev/urandom", "r");
> > +    if (f) {
> > +        int ret = fread(&seed, sizeof(seed), 1, f);
> > +        if (ret != 1)
> > +                DEBUG("unable to fread /dev/urandom, %s, fallback to
> > time+pid rand seed", strerror(errno));
> > +        fclose(f);
> > +    }
> > +
> > +    if (srand_it)
> > +        srand(seed);
> > +
> > +    return seed;
> > +}
> > diff --git a/src/lxc/utils.h b/src/lxc/utils.h
> > index 1121d74..ab2bd84 100644
> > --- a/src/lxc/utils.h
> > +++ b/src/lxc/utils.h
> > @@ -257,5 +257,7 @@ extern void lxc_free_array(void **array, lxc_free_fn
> > element_free_fn);
> >  extern size_t lxc_array_len(void **array);
> >  
> >  extern void **lxc_append_null_to_array(void **array, size_t count);
> > +//initialize rand with urandom
> > +extern int randseed(bool);
> >  
> >  #endif
> > -- 
> > 1.8.3.2
> > 
> > 
> > _______________________________________________
> > lxc-devel mailing list
> > lxc-devel at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-devel
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