[libvirt] [PATCHv2 0/2] disable default gateway in IPv6 RA for isolated networks

[Maxim Perevedentsev]

In case of DHCPv6 in isolated network, we start dnsmasq
which sends Router Advertisements (RA). If RA containts no gateway
then the link-local address of the source of RA is considered
a gateway (and guest installs a corresponding default route).

If a guest has two network interfaces (public and isolated network)
and the user installs a default route through "public" interface,
the guest will have something like

default via fe80::ffff:1:1 dev eth2  metric 1024
default via fe80::5054:ff:fe0a:d808 dev eth3  proto ra  metric 1024  expires 1789sec

RA route metric may vary, and it is preferred.
The validity of default route is controlled by
"default [route] lifetime" field in RA. If it is 0, then
the default gateway announced is considered invalid,
and no default route is installed into guest.

dnsmasq 2.67+ supports "ra-param=<interface>,<RA interval>,<default lifetime>"
option. We can pass "ra-param=*,0,0" (here, RA_interval=0 means default)
to disable default gateway in RA.

This patchset adds detection for "ra-param" in dnsmasq and
sets "ra-param=*,0,0" for isolated network if dnsmasq supports it.

Maxim Perevedentsev (2):
  Fix message about dnsmasq BINDTODEVICE capability.
  dnsmasq: disable IPv6 default gateway in RA for isolated networks

 src/network/bridge_driver.c | 7 +++++++
 src/util/virdnsmasq.c       | 8 ++++++--
 src/util/virdnsmasq.h       | 1 +
 3 files changed, 14 insertions(+), 2 deletions(-)

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1.8.3.1