[ovs-dev] [PATCH] OVN: select a random mac_prefix if not provided

[Lorenzo Bianconi]

> Looks good to me. The only potential issue here is that this constitutes a
> change in behavior with no configuration change. Is there a good place to
> note this so that it is clear to people who upgrade? Perhaps a NEWS entry?
> 

ack, fine. I will post a v2 adding an entry in NEWS.
Ben do you agree?

Regards,
Lorenzo

> On 2/20/19 10:53 AM, Lorenzo Bianconi wrote:
> > Select a random IPAM mac_prefix if it has not been provided by the user.
> > With this patch the admin can avoid to configure mac_prefix in order to
> > avoid L2 address collisions if multiple OVN deployments share the same
> > broadcast domain.
> > Remove MAC_ADDR_PREFIX definitions/occurrences since now mac_prefix is
> > always provided to ovn-northd
> > 
> > Tested-by: Miguel Duarte de Mora Barroso <mdbarroso at redhat.com>
> > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi at redhat.com>
> > ---
> >   ovn/northd/ovn-northd.c | 30 +++++++++++-------------------
> >   tests/ovn.at            |  3 +++
> >   2 files changed, 14 insertions(+), 19 deletions(-)
> > 
> > diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
> > index 3569ea2be..2b7a3634e 100644
> > --- a/ovn/northd/ovn-northd.c
> > +++ b/ovn/northd/ovn-northd.c
> > @@ -62,7 +62,6 @@ static const char *ovnnb_db;
> >   static const char *ovnsb_db;
> >   static const char *unixctl_path;
> > -#define MAC_ADDR_PREFIX 0x0A0000000000ULL
> >   #define MAC_ADDR_SPACE 0xffffff
> >   /* MAC address management (macam) table of "struct eth_addr"s, that holds the
> > @@ -937,13 +936,8 @@ ipam_insert_mac(struct eth_addr *ea, bool check)
> >       }
> >       uint64_t mac64 = eth_addr_to_uint64(*ea);
> > -    uint64_t prefix;
> > +    uint64_t prefix = eth_addr_to_uint64(mac_prefix);
> > -    if (!eth_addr_is_zero(mac_prefix)) {
> > -        prefix = eth_addr_to_uint64(mac_prefix);
> > -    } else {
> > -        prefix = MAC_ADDR_PREFIX;
> > -    }
> >       /* If the new MAC was not assigned by this address management system or
> >        * check is true and the new MAC is a duplicate, do not insert it into the
> >        * macam hmap. */
> > @@ -1056,11 +1050,7 @@ ipam_get_unused_mac(ovs_be32 ip)
> >       for (i = 0; i < MAC_ADDR_SPACE - 1; i++) {
> >           /* The tentative MAC's suffix will be in the interval (1, 0xfffffe). */
> >           mac_addr_suffix = ((base_addr + i) % (MAC_ADDR_SPACE - 1)) + 1;
> > -        if (!eth_addr_is_zero(mac_prefix)) {
> > -            mac64 =  eth_addr_to_uint64(mac_prefix) | mac_addr_suffix;
> > -        } else {
> > -            mac64 = MAC_ADDR_PREFIX | mac_addr_suffix;
> > -        }
> > +        mac64 =  eth_addr_to_uint64(mac_prefix) | mac_addr_suffix;
> >           eth_addr_from_uint64(mac64, &mac);
> >           if (!ipam_is_duplicate_mac(&mac, mac64, true)) {
> >               break;
> > @@ -1132,13 +1122,7 @@ dynamic_mac_changed(const char *lsp_addresses,
> >      }
> >      uint64_t mac64 = eth_addr_to_uint64(update->current_addresses.ea);
> > -   uint64_t prefix;
> > -
> > -   if (!eth_addr_is_zero(mac_prefix)) {
> > -       prefix = eth_addr_to_uint64(mac_prefix);
> > -   } else {
> > -       prefix = MAC_ADDR_PREFIX;
> > -   }
> > +   uint64_t prefix = eth_addr_to_uint64(mac_prefix);
> >      if ((mac64 ^ prefix) >> 24) {
> >          return DYNAMIC;
> > @@ -7300,6 +7284,14 @@ ovnnb_db_run(struct northd_context *ctx,
> >                        &addr.ea[0], &addr.ea[1], &addr.ea[2])) {
> >               mac_prefix = addr;
> >           }
> > +    } else {
> > +        eth_addr_random(&mac_prefix);
> > +        memset(&mac_prefix.ea[3], 0, 3);
> > +
> > +        char *addr_prefix = xasprintf(ETH_ADDR_FMT, ETH_ADDR_ARGS(mac_prefix));
> > +        smap_add((struct smap *)&nb->options, "mac_prefix", addr_prefix);
> > +        nbrec_nb_global_set_options(nb, &nb->options);
> > +        free(addr_prefix)
> >       }
> >       cleanup_macam(&macam);
> > diff --git a/tests/ovn.at b/tests/ovn.at
> > index cfdbf412c..7e69808ed 100644
> > --- a/tests/ovn.at
> > +++ b/tests/ovn.at
> > @@ -5416,6 +5416,7 @@ ovn_start
> >   # Add a port to a switch that does not have a subnet set, then set the
> >   # subnet which should result in an address being allocated for the port.
> > +ovn-nbctl --wait=hv set NB_Global . options:mac_prefix="0a:00:00:00:00:00"
> >   ovn-nbctl ls-add sw0
> >   ovn-nbctl lsp-add sw0 p0 -- lsp-set-addresses p0 dynamic
> >   ovn-nbctl --wait=sb add Logical-Switch sw0 other_config subnet=192.168.1.0/24
> > @@ -5801,6 +5802,7 @@ ovn_start
> >   ovn-nbctl lr-add R1
> >   # Test for a ping using dynamically allocated addresses.
> > +ovn-nbctl --wait=hv set NB_Global . options:mac_prefix="0a:00:00:00:00:00"
> >   ovn-nbctl ls-add foo -- add Logical_Switch foo other_config subnet=192.168.1.0/24
> >   ovn-nbctl ls-add alice -- add Logical_Switch alice other_config subnet=192.168.2.0/24
> > @@ -12052,6 +12054,7 @@ AT_CLEANUP
> >   AT_SETUP([ovn -- ipam to non-ipam])
> >   ovn_start
> > +ovn-nbctl --wait=hv set NB_Global . options:mac_prefix="0a:00:00:00:00:00"
> >   ovn-nbctl ls-add sw0
> >   ovn-nbctl lsp-add sw0 p0 -- lsp-set-addresses p0 dynamic
> >   ovn-nbctl --wait=sb add Logical-Switch sw0 other_config subnet=192.168.1.0/24
> > 
>