December 2024 - Bird-users

another bug
by Radu Anghel 19 Dec '24

19 Dec '24

Another one: Since killing bird is now safe-ish, I added one more bird3 to the party. Then I tried killing the first bird again. This caused the new bird3 to get stuck with BGP into Flush: BGP_IPv4 BGP --- flush 2024-12-19 16:35:08 Flush Socket: Connection reset by peer BGP_IPv6 BGP --- flush 2024-12-19 16:35:06 Flush Socket: Connection reset by peer No errors are logged on this second bird after the "Connection reset by peer" stuff, the first bird is retrying to connect, I see that with tcpdump. birdc restart BGP_IPvx does nothing birdc [dis|en]able BGP_IPvx also changes nothing Some more info about this new bird: - it is a RR so iBGP - has MD5 enabled for the sessions - import/export tables on - extended messages on - add paths on Tried it with killing multiple bird2s instead of bird3-bird3: - the ones with low number of routes (in my case <10k) do not get stuck Flushing - the ones with one (or more) full tables get stuck Flushing on the RR Killing birds looks like a theme since I have to kill the Flushing bird3 to get it to reconnect those sessions. The template from the Flushing bird RR (looks the same for v6): template bgp BGP_v4_t { debug { events }; disabled off; local as ASN; enable extended messages on; igp metric off; prefer older on; rr client; rr cluster id 0.0.0.1; ipv4 { add paths on; import limit 3000000 action warn; import filter BGP_IN4; export filter BGP_OUT4; import table on; export table on; }; } Cheers, Radu

1 0

Bug Report: Unaligned Access in BGP Code on ARMv7 Platforms
by nick 19 Dec '24

19 Dec '24

Dear BIRD Community, I am writing to report a bug observed in the BGP implementation on ARMv7 platforms, which results in a SIGBUS error due to unaligned memory access in the NEON assembler code. I debugged this issue on version 2.15.1 of BIRD. ### Problem Description When running BIRD on ARMv7, the application crashes with a `SIGBUS` signal. The issue stems from an unaligned memory access instruction in the NEON assembly: ``` vst1.8 {d16-d17}, [r0 :64] ``` This instruction requires the address in `r0` to be 64-bit (8-byte) aligned. However, in some cases, `r0` is not correctly aligned, leading to a bus error. Here is an excerpt from the kernel logs showing the alignment trap: ``` kern.err kernel: [90636.175853] Alignment trap: not handling instruction f4400a1f at [<00056fbc>] kern.alert kernel: [90636.182044] Unhandled fault: alignment exception (0x801) at 0xb6dec01c kern.alert kernel: [90636.184946] pgd = 190a2833 kern.alert kernel: [90636.191494] [b6dec01c] *pgd=82e91835, *pte=8502b75f, *ppte=8502bc7f ``` ### Backtrace The crash occurs in the `bgp_get_prefix` function due to the misaligned memory address: ``` Program received signal SIGBUS, Bus error. 0x00057504 in bgp_get_prefix (path_id=0, net=0xb6f3e030, c=0xb6f27420) at proto/bgp/attrs.c:1710 1710 proto/bgp/attrs.c: No such file or directory. (gdb) bt #0 0x00057504 in bgp_get_prefix (path_id=0, net=0xb6f3e030, c=0xb6f27420) at proto/bgp/attrs.c:1710 #1 bgp_rt_notify (old=0x400, new=0x64, n=0x4, C=0xb6f27420, P=0xb6f27850) at proto/bgp/attrs.c:1966 #2 bgp_rt_notify (P=0xb6f27850, C=0xb6f27420, n=0x4, new=0x64, old=0x0) at proto/bgp/attrs.c:1936 ... ``` The exact crashing line is this instruction: ```c px->path_id = path_id; ``` You can view it here: https://github.com/CZ-NIC/bird/blob/0b684a43bd7ce4a32c9cd7754b88286bcd1815b… ### Root Cause The root cause appears to be insufficient alignment of memory allocated for structures, specifically in this line: ```c px = mb_alloc(c->pool, sizeof(struct bgp_prefix) + net->length); ``` The allocated memory may not be properly aligned for structures containing 64-bit data types, which is mandatory on ARMv7 when using NEON instructions. ### Temporary Workaround To mitigate the issue, we are currently using the GCC compiler flag `-mno-unaligned-access`. This flag ensures that the compiler avoids generating code that assumes unaligned access is supported, thereby preventing the `SIGBUS` error. https://github.com/freifunk-berlin/falter-packages/commit/fcce390fc57b44593… ### Request for Feedback I would like to hear the community's thoughts on the best approach to resolve this issue permanently. If needed, I can provide further logs or test configurations to reproduce the problem. Bests, Nick

2 12

coredumps with Bird 3.0.0 with bfd authentication enabled
by Daniel Suchy 18 Dec '24

18 Dec '24

Hello, with Bird 3.0.0 I'm experiencing crashes during `birdc configure`. During quick debugging I figured it's somewhat related to BFD - in my use case I have keyed SHA1 authentication enabled (but similar issue I had with simple BFD session authentication). With session authentication disabled, there's no issue. With BFD session authentication enabled, first configure call after daemon start isn't problem, but second causes seqfault. I'm using pre-build packages from pkg.labs.nic.cz. Issue observed on amd64 and armhf builds. Also discovered, that I have to fully restart daemon to take authentication configuration change in effect (configure doesn't reflect the change) - this quite complicated debugging :-) crash as seen in dmesg: kernel: bird[1535627]: segfault at 0 ip 00005563d2355893 sp 00007fbd6e5fc3e8 error 4 in bird[4e893,5563d231b000+100000] likely on CPU 2 (core 2, socket 0) kernel: Code: 1f 84 00 00 00 00 00 31 ff 48 89 f8 c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 4c 8b 05 15 14 14 00 48 85 ff 74 36 48 8b 0f <48> 8b 01 48 85 c0 75 13 eb 29 0f 1f 00 48 8b 10 48 89 c1 48 85 d2 From coredump: Module libzstd.so.1 Stack trace of thread 1535627: #0 0x00005563d2355893 n/a (n/a + 0x0) #1 0x00005563d2380fe9 n/a (n/a + 0x0) #2 0x00005563d23e9085 n/a (n/a + 0x0) #3 0x00005563d23eaa90 n/a (n/a + 0x0) #4 0x00005563d23ec429 n/a (n/a + 0x0) #5 0x00005563d23475ef n/a (n/a + 0x0) #6 0x00005563d23eb78f n/a (n/a + 0x0) #7 0x00007fbd70749f52 n/a (libc.so.6 + 0x91f52) #8 0x00007fbd707c8678 n/a (libc.so.6 + 0x110678) Stack trace of thread 1535624: #0 0x00007fbd707bae9f __poll (libc.so.6 + 0x102e9f) #1 0x00005563d23eb82e n/a (n/a + 0x0) #2 0x00007fbd70749f52 n/a (libc.so.6 + 0x91f52) #3 0x00007fbd707c8678 n/a (libc.so.6 + 0x110678) Stack trace of thread 1535623: #0 0x00007fbd707bae9f __poll (libc.so.6 + 0x102e9f) #1 0x00005563d231e035 n/a (n/a + 0x0) #2 0x00007fbd706e1d68 n/a (libc.so.6 + 0x29d68) #3 0x00007fbd706e1e25 __libc_start_main (libc.so.6 + 0x29e25) #4 0x00005563d231e985 n/a (n/a + 0x0) ELF object binary architecture: AMD x86-64 - Daniel

1 0

BIRD 3.0.0
by Ondrej Filip 18 Dec '24

18 Dec '24

Dear BIRD Users, I know that some of you lost faith, but it's real! We are releasing BIRD version 3.0.0. After more than 5 years of sustained development, we came to conclusion that it's stable enough to be released. The feature list is the same as BIRD 2.16. But this version is multithreaded. By default, it spins one worker thread for BGP, BMP, RPKI and Pipe, another one for BFD, and the rest stays in the main thread. To enable this, we had to do a huge amount of internal reworks, so the table and channel implementation is very much different now. The protocols stayed almost the same. There are some minor breaking changes in config and CLI, most notably unified route attribute names to the filter variant. We are expecting to add a compatibility mode for the CLI. Anyway, it should be possible to reuse most of the configs and CLI scriptings from BIRD 2. The memory consumption has gone up significantly. We are still working on reducing the memory footprint and the next versions should be better in that. There is some documentation about what has changed between BIRD 2 and BIRD 3 from the users' perspective in doc/migration-bird3.md. if you find anything missing in that file, please send a patch, it would be deeply appreciated. We are expecting to keep developing BIRD 2 and BIRD 3 side by side for some more time as there are some old branches rooted in BIRD 2. New projects and contributions should primarily target BIRD 3 though. Thank you for running BIRD and testing the alpha versions. Your feedback and contributions have been instrumental in reaching this milestone. We look forward to hearing your experience with BIRD 3. As always, the tarball is available at https://bird.network.cz/download/bird-3.0.0.tar.gz and you can also setup our BIRD 3 repositories for Debian and Ubuntu: https://pkg.labs.nic.cz/doc/?project=bird Let me thank the whole BIRD team and specifically Maria as the team leader! Thank you so much guys! Merry routing! On behalf of the BIRD team Ondrej

4 3

[PATCH] Bus error on ARMv7 when using OSPF
by Matthew Reeve 18 Dec '24

18 Dec '24

Hi, when using bird 2.0.8 on openwrt 21.02 (and other versions) on a Netgear R7800 router, if the OSPF protocol is used, either v2 or v3, bird immediately crashes on startup with: Fri Jun 11 14:41:11 2021 daemon.info bird: Started Fri Jun 11 14:41:11 2021 kern.err kernel: [ 3500.853248] Alignment trap: not handling instruction f44c0a1f at [<00035848>] Fri Jun 11 14:41:11 2021 kern.alert kernel: [ 3500.853283] 8<--- cut here --- Fri Jun 11 14:41:11 2021 kern.alert kernel: [ 3500.859363] Unhandled fault: alignment exception (0x801) at 0x007e0624 Fri Jun 11 14:41:11 2021 kern.alert kernel: [ 3500.862443] pgd = 0bbef4fd Fri Jun 11 14:41:11 2021 kern.alert kernel: [ 3500.868821] [007e0624] *pgd=5d6ca835, *pte=5c40b75f, *ppte=5c40bc7f This router uses an ARMv7 processor and the issue seems to be to do with memory alignment issues. I've debugged it and traced it to an access to the top_hash_entry struct. I've found that if I add the PACKED macro to the struct definition then it fixes the problem, as per this patch: --- a/proto/ospf/topology.h +++ b/proto/ospf/topology.h @@ -41,7 +41,7 @@ struct top_hash_entry u8 mode; /* LSA generated during RT calculation (LSA_RTCALC or LSA_STALE)*/ u8 nhs_reuse; /* Whether nhs nodes can be reused during merging. See a note in rt.c:add_cand() */ -}; +} PACKED; /* Prevents ospf_hash_find() to ignore the entry, for p->lsrqh and p->lsrth */ Thanks.

4 11

Bird 3 Status
by Marcelo Balbinot 18 Dec '24

18 Dec '24

Hi BIRD Team, Could you give us a brief update on the status of version 3 ? Do you have any expected dates for a new release !? Thanks, -- Marcelo Balbinot

3 5

RPKI protocol is loop starting if the min version is not available
by Alarig Le Lay 16 Dec '24

16 Dec '24

Hello, Following the 2.16 release with ASPA support, I tried to play with it. So I tried to connect a bird instance to a RTR server with version 2 as stated by https://bird.network.cz/?get_doc&v=20&f=bird-6.html#ss6.16 > The same protocol, since version 2, also receives and maintains a set > of ASPAs. You can then validate AS paths using function aspa_check() > in (import) filters. It seems that I misconfigured my routinator, but instead of an error with a timer, it tries to reconnect right away, which fail again, etc. Here are the logs: Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Connected Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.roa4: State changed to UP Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.roa6: State changed to UP Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.aspa: State changed to UP Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: State changed to up Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Changing from Connecting to Sync-Start state Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Sending Reset Query packet Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Received Error packet (Unsupported-Protocol-Version: 'only versions 0 up to and including MAX_VERSION supported', Reset Query packet: 02 02 00 00 00 00 00 08) Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Client uses unsupported protocol version Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Got UNSUPPORTED_PROTOCOL_VER error PDU with invalid values, current version: 2, PDU version: 1 Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Changing from Sync-Start to Fatal-Protocol-Error state Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.roa4: State changed to FLUSHING Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.roa6: State changed to FLUSHING Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.aspa: State changed to FLUSHING Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: State changed to flush Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.roa4: State changed to DOWN Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.roa6: State changed to DOWN Dec 16 13:27:54 edge03-stolon bird: rpki_rr3.aspa: State changed to DOWN Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: State changed to down Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Starting Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Changing from Down to Connecting state Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Opening a connection Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: State changed to start Dec 16 13:27:54 edge03-stolon bird: rpki_rr3: Connected And here is the config I used: protocol rpki rpki_rr3 { debug all; roa4 { table r4; }; roa6 { table r6; }; aspa { table at; }; remote "rr3.swordarmor.fr"; min version 2; max version 2; disabled; } -- Alarig

3 3

[PATCH v3] Babel: Replace internal route selection by bird's nest
by Daniel Gröber 11 Dec '24

11 Dec '24

This allows for filtering routes from specific interfaces and neighbours. With the current internal route selection proto babel exports only up to one route and an admin cannot do fine-grained filtering. To fix this we rip out the internal route selection entirely and put them all into the bird's nest instead. This appears to not actually be a breaking change as route announcement was already based on which routes bird would send back to babel_rt_notify filters shouldn't be able to tell the difference between a single and multiple routes AFAIK. --- Changes in v3: - Subsume FIB_RESTART v2 patch: instead of restarting FIB iteration we keep lists of actions to perform after FIB iteration is finished. proto/babel/babel.c | 269 +++++++++++++++++++------------------------- proto/babel/babel.h | 8 +- 2 files changed, 120 insertions(+), 157 deletions(-) diff --git a/proto/babel/babel.c b/proto/babel/babel.c index ff8b6b52..087fd95b 100644 --- a/proto/babel/babel.c +++ b/proto/babel/babel.c @@ -29,10 +29,11 @@ * possible routes for the prefix are tracked as &babel_route entries and the * feasibility distance is maintained through &babel_source structures. * - * The main route selection is done in babel_select_route(). This is called when - * an entry is updated by receiving updates from the network or when modified by - * internal timers. The function selects from feasible and reachable routes the - * one with the lowest metric to be announced to the core. + * The main route selection is done by the bird nest (heh). For each prefix we + * export all feasible routes to the core with a distinct source (rte_src) per + * neihbour. Bird will then notify us of the optimal one by calling + * babel_rt_notify and we remember which neighbour it selected in + * babel_entry.selected_nbr. */ #include <stdlib.h> @@ -50,7 +51,7 @@ static inline int ge_mod64k(uint a, uint b) { return (u16)(a - b) < 0x8000; } static void babel_expire_requests(struct babel_proto *p, struct babel_entry *e); -static void babel_select_route(struct babel_proto *p, struct babel_entry *e, struct babel_route *mod); +static void babel_announce_rte(struct babel_proto *p, struct babel_entry *e, struct babel_route *r); static inline void babel_announce_retraction(struct babel_proto *p, struct babel_entry *e); static void babel_send_route_request(struct babel_proto *p, struct babel_entry *e, struct babel_neighbor *n); static void babel_send_seqno_request(struct babel_proto *p, struct babel_entry *e, struct babel_seqno_request *sr, struct babel_neighbor *n); @@ -164,13 +165,19 @@ babel_get_route(struct babel_proto *p, struct babel_entry *e, struct babel_neigh return r; } +static struct babel_route * +babel_get_selected_route(struct babel_proto *p, struct babel_entry *e) +{ + if (e->selected_nbr) + return babel_get_route(p, e, e->selected_nbr); + return NULL; +} + static inline void babel_retract_route(struct babel_proto *p, struct babel_route *r) { r->metric = r->advert_metric = BABEL_INFINITY; - - if (r == r->e->selected) - babel_select_route(p, r->e, r); + babel_announce_rte(p, r->e, r); } static void @@ -182,9 +189,6 @@ babel_flush_route(struct babel_proto *p UNUSED, struct babel_route *r) rem_node(NODE r); rem_node(&r->neigh_route); - if (r->e->selected == r) - r->e->selected = NULL; - sl_free(r); } @@ -200,6 +204,7 @@ babel_expire_route(struct babel_proto *p, struct babel_route *r) { r->metric = r->advert_metric = BABEL_INFINITY; r->expires = current_time() + cf->hold_time; + babel_announce_rte(p, r->e, r); } else { @@ -210,7 +215,7 @@ babel_expire_route(struct babel_proto *p, struct babel_route *r) static void babel_refresh_route(struct babel_proto *p, struct babel_route *r) { - if (r == r->e->selected) + if (r == babel_get_selected_route(p, r->e)) babel_send_route_request(p, r->e, r->neigh); r->refresh_time = 0; @@ -221,16 +226,15 @@ babel_expire_routes_(struct babel_proto *p, struct fib *rtable) { struct babel_config *cf = (void *) p->p.cf; struct babel_route *r, *rx; + struct babel_entry *retract_head = NULL, *delete_head = NULL; + struct babel_route *expire_head = NULL; struct fib_iterator fit; btime now_ = current_time(); - FIB_ITERATE_INIT(&fit, rtable); -loop: + FIB_ITERATE_INIT(&fit, rtable); FIB_ITERATE_START(rtable, &fit, struct babel_entry, e) { - int changed = 0; - WALK_LIST_DELSAFE(r, rx, e->routes) { if (r->refresh_time && r->refresh_time <= now_) @@ -238,23 +242,11 @@ loop: if (r->expires && r->expires <= now_) { - changed = changed || (r == e->selected); - babel_expire_route(p, r); + r->expire_next = expire_head; + expire_head = r; } } - if (changed) - { - /* - * We have to restart the iteration because there may be a cascade of - * synchronous events babel_select_route() -> nest table change -> - * babel_rt_notify() -> rtable change, invalidating hidden variables. - */ - FIB_ITERATE_PUT(&fit); - babel_select_route(p, e, NULL); - goto loop; - } - /* Clean up stale entries */ if ((e->valid == BABEL_ENTRY_STALE) && ((e->updated + cf->hold_time) <= now_)) e->valid = BABEL_ENTRY_DUMMY; @@ -262,9 +254,8 @@ loop: /* Clean up unreachable route */ if (e->unreachable && (!e->valid || (e->router_id == p->router_id))) { - FIB_ITERATE_PUT(&fit); - babel_announce_retraction(p, e); - goto loop; + e->retract_next = retract_head; + retract_head = e; } babel_expire_sources(p, e); @@ -273,12 +264,25 @@ loop: /* Remove empty entries */ if (!e->valid && EMPTY_LIST(e->routes) && EMPTY_LIST(e->sources) && EMPTY_LIST(e->requests)) { - FIB_ITERATE_PUT(&fit); - fib_delete(rtable, e); - goto loop; + e->delete_next = delete_head; + delete_head = e; } } FIB_ITERATE_END; + + for (struct babel_route *r_next, *r = expire_head; r ; r = r_next) { + r_next = r->expire_next; + babel_expire_route(p, r); + } + + for (struct babel_entry *e = retract_head; e ; e = e->retract_next) { + babel_announce_retraction(p, e); + } + + for (struct babel_entry *e_next, *e = delete_head; e ; e = e_next) { + e_next = e->delete_next; + fib_delete(rtable, e); + } } static void @@ -447,6 +451,7 @@ babel_get_neighbor(struct babel_iface *ifa, ip_addr addr) nbr = mb_allocz(ifa->pool, sizeof(struct babel_neighbor)); nbr->ifa = ifa; + nbr->src = rt_get_source(&p->p, idm_alloc(&p->src_ids)); nbr->addr = addr; nbr->rxcost = BABEL_INFINITY; nbr->txcost = BABEL_INFINITY; @@ -474,6 +479,8 @@ babel_flush_neighbor(struct babel_proto *p, struct babel_neighbor *nbr) } nbr->ifa = NULL; + + idm_free(&p->src_ids, nbr->src->private_id); rem_node(NODE nbr); mb_free(nbr); } @@ -634,11 +641,40 @@ done: WALK_LIST2(r, n, nbr->routes, neigh_route) { r->metric = babel_compute_metric(nbr, r->advert_metric); - babel_select_route(p, r->e, r); + babel_announce_rte(p, r->e, r); } } } +static void +babel_announce_rte_unreachable(struct babel_proto *p, struct babel_entry *e, u8 unreachable) +{ + struct channel *c = (e->n.addr->type == NET_IP4) ? p->ip4_channel : p->ip6_channel; + rte *rte = NULL; + + if (unreachable) { + /* Unreachable */ + rta a0 = { + .source = RTS_BABEL, + .scope = SCOPE_UNIVERSE, + .dest = RTD_UNREACHABLE, + .pref = 1, + }; + + rta *a = rta_lookup(&a0); + rte = rte_get_temp(a, p->p.main_source); + } + + e->unreachable = unreachable; + + /* Unlike the many neighbour routes we only want one unreachable route, for + * one it's ugly to have lots of unreachable routes (if we just did this right + * in babel_announce_rte) but we also loose access to the neibour rte_src id + * when the neighbour is deallocated. This happens on a different schedule + * than unreachable route removal. */ + rte_update2(c, e->n.addr, rte, p->p.main_source); +} + /** * babel_announce_rte - announce selected route to the core * @p: Babel protocol instance @@ -649,12 +685,11 @@ done: * the entry is valid and ours, the unreachable route is announced instead. */ static void -babel_announce_rte(struct babel_proto *p, struct babel_entry *e) +babel_announce_rte(struct babel_proto *p, struct babel_entry *e, struct babel_route *r) { - struct babel_route *r = e->selected; struct channel *c = (e->n.addr->type == NET_IP4) ? p->ip4_channel : p->ip6_channel; - if (r) + if (r->metric != BABEL_INFINITY && r->feasible) { rta a0 = { .source = RTS_BABEL, @@ -698,124 +733,27 @@ babel_announce_rte(struct babel_proto *p, struct babel_entry *e) a0.nh.flags = RNF_ONLINK; rta *a = rta_lookup(&a0); - rte *rte = rte_get_temp(a, p->p.main_source); + rte *rte = rte_get_temp(a, r->neigh->src); - e->unreachable = 0; - rte_update2(c, e->n.addr, rte, p->p.main_source); - } - else if (e->valid && (e->router_id != p->router_id)) - { - /* Unreachable */ - rta a0 = { - .source = RTS_BABEL, - .scope = SCOPE_UNIVERSE, - .dest = RTD_UNREACHABLE, - .pref = 1, - }; - - rta *a = rta_lookup(&a0); - rte *rte = rte_get_temp(a, p->p.main_source); - - e->unreachable = 1; - rte_update2(c, e->n.addr, rte, p->p.main_source); + rte_update2(c, e->n.addr, rte, r->neigh->src); + babel_announce_rte_unreachable(p, e, 0); } else - { - /* Retraction */ - e->unreachable = 0; - rte_update2(c, e->n.addr, NULL, p->p.main_source); - } + rte_update2(c, e->n.addr, NULL, r->neigh->src); } /* Special case of babel_announce_rte() just for retraction */ static inline void babel_announce_retraction(struct babel_proto *p, struct babel_entry *e) { + TRACE(D_EVENTS, "Retract unreachable route for %N", + e->n.addr); + struct channel *c = (e->n.addr->type == NET_IP4) ? p->ip4_channel : p->ip6_channel; e->unreachable = 0; rte_update2(c, e->n.addr, NULL, p->p.main_source); } - -/** - * babel_select_route - select best route for given route entry - * @p: Babel protocol instance - * @e: Babel entry to select the best route for - * @mod: Babel route that was modified or NULL if unspecified - * - * Select the best reachable and feasible route for a given prefix among the - * routes received from peers, and propagate it to the nest. This just selects - * the reachable and feasible route with the lowest metric, but keeps selected - * the old one in case of tie. - * - * If no feasible route is available for a prefix that previously had a route - * selected, a seqno request is sent to try to get a valid route. If the entry - * is valid and not owned by us, the unreachable route is announced to the nest - * (to blackhole packets going to it, as per section 2.8). It is later removed - * by babel_expire_routes(). Otherwise, the route is just removed from the nest. - * - * Argument @mod is used to optimize best route calculation. When specified, the - * function can assume that only the @mod route was modified to avoid full best - * route selection and announcement when non-best route was modified in minor - * way. The caller is advised to not call babel_select_route() when no change is - * done (e.g. periodic route updates) to avoid unnecessary announcements of the - * same best route. The caller is not required to call the function in case of a - * retraction of a non-best route. - * - * Note that the function does not active triggered updates. That is done by - * babel_rt_notify() when the change is propagated back to Babel. - */ -static void -babel_select_route(struct babel_proto *p, struct babel_entry *e, struct babel_route *mod) -{ - struct babel_route *r, *best = e->selected; - - /* Shortcut if only non-best was modified */ - if (mod && (mod != best)) - { - /* Either select modified route, or keep old best route */ - if ((mod->metric < (best ? best->metric : BABEL_INFINITY)) && mod->feasible) - best = mod; - else - return; - } - else - { - /* Selected route may be modified and no longer admissible */ - if (!best || (best->metric == BABEL_INFINITY) || !best->feasible) - best = NULL; - - /* Find the best feasible route from all routes */ - WALK_LIST(r, e->routes) - if ((r->metric < (best ? best->metric : BABEL_INFINITY)) && r->feasible) - best = r; - } - - if (best) - { - if (best != e->selected) - TRACE(D_EVENTS, "Picked new route for prefix %N: router-id %lR metric %d", - e->n.addr, best->router_id, best->metric); - } - else if (e->selected) - { - /* - * We have lost all feasible routes. We have to broadcast seqno request - * (Section 3.8.2.1) and keep unreachable route for a while (section 2.8). - * The later is done automatically by babel_announce_rte(). - */ - - TRACE(D_EVENTS, "Lost feasible route for prefix %N", e->n.addr); - if (e->valid && (e->selected->router_id == e->router_id)) - babel_add_seqno_request(p, e, e->selected->router_id, e->selected->seqno + 1, 0, NULL); - } - else - return; - - e->selected = best; - babel_announce_rte(p, e); -} - /* * Functions to send replies */ @@ -1300,7 +1238,7 @@ babel_handle_update(union babel_msg *m, struct babel_iface *ifa) s = babel_find_source(e, msg->router_id); /* for feasibility */ feasible = babel_is_feasible(s, msg->seqno, msg->metric); metric = babel_compute_metric(nbr, msg->metric); - best = e->selected; + best = babel_get_selected_route(p, e); /* * RFC section 3.8.2.2 - Dealing with unfeasible updates. Generate a one-off @@ -1338,7 +1276,7 @@ babel_handle_update(union babel_msg *m, struct babel_iface *ifa) e->updated = current_time(); } - babel_select_route(p, e, r); + babel_announce_rte(p, e, r); } void @@ -2003,10 +1941,10 @@ babel_dump_route(struct babel_route *r) } static void -babel_dump_entry(struct babel_entry *e) +babel_dump_entry(struct babel_proto *p, struct babel_entry *e) { struct babel_source *s; - struct babel_route *r; + struct babel_route *r, *best = babel_get_selected_route(p, e); debug("Babel: Entry %N:\n", e->n.addr); @@ -2016,7 +1954,7 @@ babel_dump_entry(struct babel_entry *e) WALK_LIST(r,e->routes) { debug(" "); - if (r == e->selected) debug("*"); + if (r == best) debug("*"); babel_dump_route(r); } } @@ -2057,12 +1995,12 @@ babel_dump(struct proto *P) FIB_WALK(&p->ip4_rtable, struct babel_entry, e) { - babel_dump_entry(e); + babel_dump_entry(p, e); } FIB_WALK_END; FIB_WALK(&p->ip6_rtable, struct babel_entry, e) { - babel_dump_entry(e); + babel_dump_entry(p, e); } FIB_WALK_END; } @@ -2186,7 +2124,7 @@ babel_show_entries_(struct babel_proto *p, struct fib *rtable) FIB_WALK(rtable, struct babel_entry, e) { - struct babel_route *r = NULL; + struct babel_route *r = NULL, *best = babel_get_selected_route(p, e); uint rts = 0, srcs = 0; node *n; @@ -2199,7 +2137,7 @@ babel_show_entries_(struct babel_proto *p, struct fib *rtable) if (e->valid) cli_msg(-1025, "%-*N %-23lR %6u %5u %7u %7u", width, e->n.addr, e->router_id, e->metric, e->seqno, rts, srcs); - else if (r = e->selected) + else if (r = best) cli_msg(-1025, "%-*N %-23lR %6u %5u %7u %7u", width, e->n.addr, r->router_id, r->metric, r->seqno, rts, srcs); else @@ -2236,10 +2174,10 @@ babel_show_routes_(struct babel_proto *p, struct fib *rtable) FIB_WALK(rtable, struct babel_entry, e) { - struct babel_route *r; + struct babel_route *r, *best = babel_get_selected_route(p, e); WALK_LIST(r, e->routes) { - char c = (r == e->selected) ? '*' : (r->feasible ? '+' : ' '); + char c = (r == best) ? '*' : (r->feasible ? '+' : ' '); btime time = r->expires ? r->expires - current_time() : 0; cli_msg(-1025, "%-*N %-25I %-10s %5u %c %5u %7t", width, e->n.addr, r->next_hop, r->neigh->ifa->ifname, @@ -2320,15 +2258,18 @@ babel_rt_notify(struct proto *P, struct channel *c UNUSED, struct network *net, { struct babel_proto *p = (void *) P; struct babel_entry *e; + struct babel_iface *ifa; + struct babel_neighbor *n; if (new) { /* Update */ + uint internal = new->src->proto == P; uint rt_seqno; uint rt_metric = ea_get_int(new->attrs->eattrs, EA_BABEL_METRIC, 0); u64 rt_router_id = 0; - if (new->src->proto == P) + if (internal) { rt_seqno = ea_find(new->attrs->eattrs, EA_BABEL_SEQNO)->u.data; eattr *e = ea_find(new->attrs->eattrs, EA_BABEL_ROUTER_ID); @@ -2350,6 +2291,18 @@ babel_rt_notify(struct proto *P, struct channel *c UNUSED, struct network *net, e = babel_get_entry(p, net->n.addr); + while (internal) { + ifa = babel_find_iface(p, new->attrs->nh.iface); + if (!ifa) break; + n = babel_find_neighbor(ifa, new->attrs->from); + if (!n) break; + e->selected_nbr = n; + break; + } + if (!internal) { + e->selected_nbr = NULL; + } + /* Activate triggered updates */ if ((e->valid != BABEL_ENTRY_VALID) || (e->router_id != rt_router_id)) @@ -2373,6 +2326,9 @@ babel_rt_notify(struct proto *P, struct channel *c UNUSED, struct network *net, e->valid = BABEL_ENTRY_STALE; e->metric = BABEL_INFINITY; + e->selected_nbr = NULL; + + babel_announce_rte_unreachable(p, e, 1); babel_trigger_update(p); e->updated = current_time(); @@ -2464,6 +2420,7 @@ babel_start(struct proto *P) p->source_slab = sl_new(P->pool, sizeof(struct babel_source)); p->msg_slab = sl_new(P->pool, sizeof(struct babel_msg_node)); p->seqno_slab = sl_new(P->pool, sizeof(struct babel_seqno_request)); + idm_init(&p->src_ids, P->pool, 8); p->log_pkt_tbf = (struct tbf){ .rate = 1, .burst = 5 }; diff --git a/proto/babel/babel.h b/proto/babel/babel.h index da8386b3..1d7e19f0 100644 --- a/proto/babel/babel.h +++ b/proto/babel/babel.h @@ -25,6 +25,7 @@ #include "lib/socket.h" #include "lib/string.h" #include "lib/timer.h" +#include "lib/idm.h" #define EA_BABEL_METRIC EA_CODE(PROTOCOL_BABEL, 0) #define EA_BABEL_ROUTER_ID EA_CODE(PROTOCOL_BABEL, 1) @@ -174,6 +175,7 @@ struct babel_proto { slab *source_slab; slab *msg_slab; slab *seqno_slab; + struct idm src_ids; struct tbf log_pkt_tbf; /* TBF for packet messages */ }; @@ -216,6 +218,7 @@ struct babel_iface { struct babel_neighbor { node n; struct babel_iface *ifa; + struct rte_src *src; ip_addr addr; u16 rxcost; /* Sent in last IHU */ @@ -256,6 +259,7 @@ struct babel_source { struct babel_route { node n; node neigh_route; + struct babel_route *expire_next; struct babel_entry *e; struct babel_neighbor *neigh; @@ -281,7 +285,9 @@ struct babel_seqno_request { }; struct babel_entry { - struct babel_route *selected; + struct babel_neighbor *selected_nbr; + + struct babel_entry *retract_next, *delete_next; list routes; /* Routes for this prefix (struct babel_route) */ list sources; /* Source entries for this prefix (struct babel_source). */ -- 2.30.2

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BIRD 2.16
by Ondrej Filip 10 Dec '24

10 Dec '24

Dear BIRD Users, we are releasing version 2.16 of BIRD. We added support for ASPA, made filters better, there are also several new handy features in BFD and OSPF, and we massively optimized BMP. Considering out-of tree code, there is TCP-AO which we expect to merge soon, and EVPN support where we are still looking for more input on how the features should actually look like from the users' point of view. There is one minor breaking change: the CLI dump commands now require a filename where to dump the information. Last but not least, we described our contributions and credits policy. Most notably, if there is a pending patch from you with no answer from us within last three weeks, please resend it. We don't intend to ghost you, we are just overloaded. Version 2.16 (2024-12-04) o BFD: Set password per session o BFD: Accept zero checksum for IPv6-UDP o BMP: Refactoring and optimization o OSPF: Allow loopback nexthop in OSPFv3-IPv4 o RPKI: TCP-MD5 authentication option o Filters: Add enum types to filter grammar o CLI: Configurable additional control sockets o CLI: Timeformat command o CLI: Dump commands need a target file o ASPA support in filters, Static and RPKI o Formalized contributions and credits policy o Many bugfixes and improvements Happy routing! Ondrej & Maria

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[PATCH] Babel: fix seqno wrapping on seqno request
by Fabian Bläse 10 Dec '24

10 Dec '24

The Babel seqno wraps around when reaching its maximum value (UINT16_MAX). When comparing seqnos, this has to be taken into account. Therefore, plain number comparisons do not work. In a previous attempt to fix the wrapping behavior, one particular comparison was missed. This causes the seqno of originated babel routes to not wrap, but remain at UINT16_MAX indefinitely, resulting in slow route propagation on topology changes. Make use of the previously introduced gt_mod64k macro to compare seqnos correctly. Fixes: 3e7e4a71868bc519aacc0eb785471b46fc345a5c Signed-off-by: Fabian Bläse <fabian(a)blaese.de> --- proto/babel/babel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/proto/babel/babel.c b/proto/babel/babel.c index fe5c0599..b94b96d9 100644 --- a/proto/babel/babel.c +++ b/proto/babel/babel.c @@ -1015,7 +1015,7 @@ babel_send_update_(struct babel_iface *ifa, btime changed, struct fib *rtable) /* Our own seqno might have changed, in which case we update the routes we originate. */ - if ((e->router_id == p->router_id) && (e->seqno < p->update_seqno)) + if ((e->router_id == p->router_id) && (gt_mod64k(p->update_seqno, e->seqno)) { e->seqno = p->update_seqno; e->updated = current_time(); -- 2.47.1

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