On 17 Jan 2025, at 18:30, Martin Kalcok wrote:
> A recent commit[0] added condition to "route_table_parse__" function that
> causes it to throw error when parsing route without "nexthop
> information" (either RTA_OIF, RTA_GATEWAY, RTA_VIA or RTA_MULTIPATH). While
> this requirement is reasonable for regular routes, there are some route types
> that don't need nexthop. One of these types is "blackhole" route, that we
> intend
> to use in OVN for route advertising (RTN_BLACKHOLE)[1].
>
> This change does not enforce the above-mentioned condition for those special
> route types that don't require "nexthop information".
>
> [0]
> https://github.com/openvswitch/ovs/commit/91fc51106cfeff33901080ecb063f621eeb00f54
> [1] https://mail.openvswitch.org/pipermail/ovs-dev/2025-January/419383.html
Thanks for the patch Martin. I think you should include the fixes tag for
commit [0].
In addition, the logic of the route_table_parse__() function should also
change, as it should have an uninitialized/unused next hop in the list.
Cheers,
Eelco
> Signed-off-by: Martin Kalcok <[email protected]>
> ---
> lib/route-table.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/lib/route-table.c b/lib/route-table.c
> index 8106dc93d..c232a388f 100644
> --- a/lib/route-table.c
> +++ b/lib/route-table.c
> @@ -220,6 +220,24 @@ route_table_reset(void)
> }
> }
>
> +
> +/* Returns true if the given route requires nexhop information (output
> + interface, nexthop IP, ...). Returns false for special route types, like
> + blackhole, that don't need this information.
> + */
> +static bool
> +route_needs_nexthop(const struct rtmsg *rtm) {
> + switch (rtm->rtm_type) {
> + case RTN_BLACKHOLE:
> + case RTN_THROW:
> + case RTN_UNREACHABLE:
> + case RTN_PROHIBIT:
> + return false;
> + default:
> + return true;
> + }
> +}
> +
> static int
> route_table_parse__(struct ofpbuf *buf, size_t ofs,
> const struct nlmsghdr *nlmsg,
> @@ -430,7 +448,7 @@ route_table_parse__(struct ofpbuf *buf, size_t ofs,
> &mp_change.rd.nexthops);
> }
> }
> - if (!attrs[RTA_OIF] && !attrs[RTA_GATEWAY]
> + if (route_needs_nexthop(rtm) && !attrs[RTA_OIF] &&
> !attrs[RTA_GATEWAY]
> && !attrs[RTA_VIA] && !attrs[RTA_MULTIPATH]) {
> VLOG_DBG_RL(&rl, "route message needs an RTA_OIF, RTA_GATEWAY, "
> "RTA_VIA or RTA_MULTIPATH attribute");
> --
> 2.43.0
>
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