Re: multicast route counter
Claudio Jeker <[email protected]>
| Newsgroups | gmane.os.openbsd.tech |
|---|---|
| Message-ID | <[email protected]> |
On Wed, Jun 24, 2026 at 02:06:14PM +0200, Alexander Bluhm wrote:
> Hi,
>
> ip_mforward() contains a static variable that poorly implements a
> rate limited log message. Replace the log with a counter.
>
> While there, also count drops due to time-to-live and hop-limit.
> As the default ttl is 1, this is the most common pitfall when
> configuring multicast router. A counter helps.
>
> ok?
Sure. OK claudio@
> bluhm
>
> Index: sys/netinet/ip_mroute.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/ip_mroute.c,v
> diff -u -p -r1.152 ip_mroute.c
> --- sys/netinet/ip_mroute.c 23 Jun 2026 19:09:37 -0000 1.152
> +++ sys/netinet/ip_mroute.c 24 Jun 2026 09:42:20 -0000
> @@ -528,6 +528,8 @@ mrt_sysctl_mrtstat(void *oldp, size_t *o
> ASSIGN(mrts_q_overflow);
> ASSIGN(mrts_pkt2large);
> ASSIGN(mrts_upq_sockfull);
> + ASSIGN(mrts_time_to_live);
> + ASSIGN(mrts_source_route);
>
> #undef ASSIGN
>
> @@ -1157,7 +1159,6 @@ ip_mforward(struct mbuf *m, struct ifnet
> struct ip *ip = mtod(m, struct ip *);
> struct vif *v;
> struct rtentry *rt;
> - static int srctun = 0;
> struct mbuf *mm;
> unsigned int rtableid = ifp->if_rdomain;
>
> @@ -1172,9 +1173,7 @@ ip_mforward(struct mbuf *m, struct ifnet
> * Packet arrived through a source-route tunnel.
> * Source-route tunnels are no longer supported.
> */
> - if ((srctun++ % 1000) == 0)
> - log(LOG_ERR, "ip_mforward: received source-routed "
> - "packet from %x\n", ntohl(ip->ip_src.s_addr));
> + mrtstat_inc(mrts_source_route);
> return (EOPNOTSUPP);
> }
>
> @@ -1182,6 +1181,8 @@ ip_mforward(struct mbuf *m, struct ifnet
> * Don't forward a packet with time-to-live of zero or one,
> * or a packet destined to a local-only group.
> */
> + if (ip->ip_ttl <= 1)
> + mrtstat_inc(mrts_time_to_live);
> if (ip->ip_ttl <= 1 || IN_LOCAL_GROUP(ip->ip_dst.s_addr))
> return (0);
>
> Index: sys/netinet/ip_mroute.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/ip_mroute.h,v
> diff -u -p -r1.34 ip_mroute.h
> --- sys/netinet/ip_mroute.h 9 May 2025 14:43:47 -0000 1.34
> +++ sys/netinet/ip_mroute.h 24 Jun 2026 09:42:20 -0000
> @@ -165,6 +165,8 @@ struct mrtstat {
> u_long mrts_q_overflow; /* pkts dropped - Q overflow */
> u_long mrts_pkt2large; /* pkts dropped - size > BKT SIZE */
> u_long mrts_upq_sockfull; /* upcalls dropped - socket full */
> + u_long mrts_time_to_live; /* ip ttl not above 1 */
> + u_long mrts_source_route; /* packet from source-routed tunnel */
> };
>
> #ifdef _KERNEL
> @@ -183,6 +185,8 @@ enum mrtstat_counters {
> mrts_q_overflow,
> mrts_pkt2large,
> mrts_upq_sockfull,
> + mrts_time_to_live,
> + mrts_source_route,
> mrts_ncounters
> };
>
> Index: sys/netinet6/ip6_mroute.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/ip6_mroute.c,v
> diff -u -p -r1.157 ip6_mroute.c
> --- sys/netinet6/ip6_mroute.c 23 Jun 2026 18:50:43 -0000 1.157
> +++ sys/netinet6/ip6_mroute.c 24 Jun 2026 09:42:20 -0000
> @@ -474,6 +474,7 @@ mrt6_sysctl_mrt6stat(void *oldp, size_t
> ASSIGN(mrt6s_q_overflow);
> ASSIGN(mrt6s_pkt2large);
> ASSIGN(mrt6s_upq_sockfull);
> + ASSIGN(mrt6s_hop_limit);
>
> #undef ASSIGN
>
> @@ -938,6 +939,8 @@ ip6_mforward(struct ip6_hdr *ip6, struct
> * Don't forward a packet with Hop limit of zero or one,
> * or a packet destined to a local-only group.
> */
> + if (ip6->ip6_hlim <= 1)
> + mrt6stat_inc(mrt6s_hop_limit);
> if (ip6->ip6_hlim <= 1 || IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) ||
> IN6_IS_ADDR_MC_LINKLOCAL(&ip6->ip6_dst))
> return 0;
> Index: sys/netinet6/ip6_mroute.h
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/ip6_mroute.h,v
> diff -u -p -r1.25 ip6_mroute.h
> --- sys/netinet6/ip6_mroute.h 19 May 2025 04:54:04 -0000 1.25
> +++ sys/netinet6/ip6_mroute.h 24 Jun 2026 09:42:20 -0000
> @@ -146,6 +146,7 @@ struct mrt6stat {
> u_int64_t mrt6s_q_overflow; /* pkts dropped - Q overflow */
> u_int64_t mrt6s_pkt2large; /* pkts dropped - size > BKT SIZE */
> u_int64_t mrt6s_upq_sockfull; /* upcalls dropped - socket full */
> + u_int64_t mrt6s_hop_limit; /* ip6 hlim not above one */
> };
>
> /*
> @@ -206,6 +207,7 @@ enum mrt6stat_counters {
> mrt6s_q_overflow,
> mrt6s_pkt2large,
> mrt6s_upq_sockfull,
> + mrt6s_hop_limit,
> mrt6s_ncounters
> };
>
> Index: usr.bin/netstat/mroute.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/usr.bin/netstat/mroute.c,v
> diff -u -p -r1.29 mroute.c
> --- usr.bin/netstat/mroute.c 6 Jun 2025 20:37:06 -0000 1.29
> +++ usr.bin/netstat/mroute.c 24 Jun 2026 09:43:28 -0000
> @@ -188,4 +188,8 @@ mrt_stats(void)
> mrtstat.mrts_pkt2large, plural(mrtstat.mrts_pkt2large));
> printf("\t%lu datagram%s dropped due to full socket buffer\n",
> mrtstat.mrts_upq_sockfull, plural(mrtstat.mrts_upq_sockfull));
> + printf("\t%lu datagram%s exceeded time-to-live not forwarded\n",
> + mrtstat.mrts_time_to_live, plural(mrtstat.mrts_time_to_live));
> + printf("\t%lu datagram%s dropped due to source-routing\n",
> + mrtstat.mrts_source_route, plural(mrtstat.mrts_source_route));
> }
> Index: usr.bin/netstat/mroute6.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/usr.bin/netstat/mroute6.c,v
> diff -u -p -r1.27 mroute6.c
> --- usr.bin/netstat/mroute6.c 6 Jun 2025 20:37:06 -0000 1.27
> +++ usr.bin/netstat/mroute6.c 24 Jun 2026 09:41:30 -0000
> @@ -221,4 +221,6 @@ mrt6_stats(void)
> mrt6stat.mrt6s_pkt2large, plural(mrt6stat.mrt6s_pkt2large));
> printf("\t%llu datagram%s dropped due to full socket buffer\n",
> mrt6stat.mrt6s_upq_sockfull, plural(mrt6stat.mrt6s_upq_sockfull));
> + printf("\t%llu datagram%s exceeded hop-limit not forwarded\n",
> + mrt6stat.mrt6s_hop_limit, plural(mrt6stat.mrt6s_hop_limit));
> }
>
--
:wq Claudio