From b62e019afad652748bcda0205f96611640bcd6d5 Mon Sep 17 00:00:00 2001 From: Justin Mayfield Date: Thu, 16 Aug 2012 19:03:48 -0600 Subject: single nexthop flags bug I ran into a bug today related to how Linux handles a route's nexthop flags when there is just one nexthop. Namely Linux expects the flags to be OR'd into the rtm_flags field when there is only one nexthop and so rtnl_route_build_msg needs to check the number of nexthops and store the nexthops flags into this field prior to calling nlmsg_append(...&rtmsg). Conversely the rtnl_route_parse function needs to pull these lower 0xff bits when a single nexthop is detected. Attached is my patch. I don't like the slight duplication of doing the rtnl_route_get_nnexthops check twice but it seemed to be the least turmoil of any solution I thought of. --- lib/route/route_obj.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/lib/route/route_obj.c b/lib/route/route_obj.c index 62669a9..7ea4fff 100644 --- a/lib/route/route_obj.c +++ b/lib/route/route_obj.c @@ -986,6 +986,7 @@ int rtnl_route_parse(struct nlmsghdr *nlh, struct rtnl_route **result) } if (old_nh) { + rtnl_route_nh_set_flags(old_nh, rtm->rtm_flags & 0xff); if (route->rt_nr_nh == 0) { /* If no nexthops have been provided via RTA_MULTIPATH * we add it as regular nexthop to maintain backwards @@ -1045,10 +1046,15 @@ int rtnl_route_build_msg(struct nl_msg *msg, struct rtnl_route *route) if (route->rt_src) rtmsg.rtm_src_len = nl_addr_get_prefixlen(route->rt_src); - if (rtmsg.rtm_scope == RT_SCOPE_NOWHERE) rtmsg.rtm_scope = rtnl_route_guess_scope(route); + if (rtnl_route_get_nnexthops(route) == 1) { + struct rtnl_nexthop *nh; + nh = rtnl_route_nexthop_n(route, 0); + rtmsg.rtm_flags |= nh->rtnh_flags; + } + if (nlmsg_append(msg, &rtmsg, sizeof(rtmsg), NLMSG_ALIGNTO) < 0) goto nla_put_failure; -- cgit v1.2.1