This commit prevents use-after-free of routes belonging to protocols
which have been already destroyed, delaying also all the protocols'
shutdown until all of their routes have been finally propagated through
all the pipes down to the appropriate exports.
The use-after-free was somehow hypothetic yet theoretically possible in
rare conditions, when one BGP protocol authors a lot of routes and the
user deletes that protocol by reconfiguring in the same time as next hop
update is requested, causing rte_better() to be called on a
not-yet-pruned network prefix while the owner protocol has been already
freed.
In parallel execution environments, this would happen an inter-thread
use-after-free, causing possible heisenbugs or other nasty problems.
Routes are now allocated only when they are just to be inserted to the
table. Updating a route needs a locally allocated route structure.
Ownership of the attributes is also now not transfered from protocols to
tables and vice versa but just borrowed which should be easier to handle
in a multithreaded environment.
Most commands like 'show ospf neighbors' fail when protocol is not
specified and there are multiple instances of given protocol type.
This is annoying in BIRD 2, as many protocols have IPv4 and IPv6
instances. The patch changes that by showing output from all protocol
instances of appropriate type.
Note that the patch also removes terminating cli_msg() call from these
commands and moves it to the common iterating code.
Per RFC 3101, N-bit signalling NSSA support should be used only in Hello
packets, not in DBDES packets. BIRD since 2.0.4 verifies N-bit in
neighbor structure, which is learned from DBDES packets, therefore
NSSA-LSAs are not propagated to proper implementations of RFC 3101.
This patch fixes that. Both removing the check and removing N-bit from
DBDES packet. This will fix compatibility issues with proper
implementations, but causes compatibility issues with BIRD 2.0.4.
We need to flush learned external LSAs a bit later than other LSAs (after
first feed after end of the graceful restart) to avoid flap of external
routes.
Implement OSPFv2 (RFC 3623) and OSPFv3 (RFC 5187) graceful restart,
for both restarting and helper sides. Graceful restart is initiated
by 'graceful down' command.
The temporary atttributes are no longer removed by ea_do_prune(), but
they are undefined by store_tmp_attrs() protocol hooks. This fixes
several bugs where temporary attributes were removed when they should
not or not removed when they should be. The flag EAF_TEMP is no longer
needed and was removed.
Update all protocol make_tmp_attrs() / store_tmp_attrs() hooks to use
helper functions and to handle unset attributes properly.
Also fix some related bugs like improper handling of empty eattr list.
Keep track of whether OSPF tmpattrs are actually defined for given route
(using flags in rte->pflags). That makes them behave more like real
eattrs so a protocol can define just a subset of them or they can be
undefined by filters.
Do not set ospf_metric2 for other than type 2 external OSPF routes and do
not set ospf_tag for non-external OSPF routes. That also fixes a bug
where internal/inter-area route propagated from one OSPF instance to
another is initiated with infinity ospf_metric2.
Thanks to Yaroslav Dronskii for the bugreport.
When area is reconfigured to a different type, we need to flush LSAs as
they may not be valid (e.g. NSSA-LSA for non-NSSA area). Also, when we
have have just one OSPF area and that changes type, we could restart OSPF
as there is no state to keep anyway. That solves issue with different
handling of external routes exported to OSPF based of main area type.
External LSAs originated by OSPF routers with VPN-PE behavior enabled are
marked by DN flag and they are ignored by other OSPF routers with VPN-PE
enabled.
Once upon a time, far far away, there were the old Bird developers
discussing what direction of route flow shall be called import and
export. They decided to say "import to protocol" and "export to table"
when speaking about a protocol. When speaking about a table, they
spoke about "importing to table" and "exporting to protocol".
The latter terminology was adopted in configuration, then also the
bird CLI in commit ea2ae6dd0 started to use it (in year 2009). Now
it's 2018 and the terminology is the latter. Import is from protocol to
table, export is from table to protocol. Anyway, there was still an
import_control hook which executed right before route export.
One thing is funny. There are two commits in April 1999 with just two
minutes between them. The older announces the final settlement
on config terminology, the newer uses the other definition. Let's see
their commit messages as the git-log tool shows them (the newer first):
commit 9e0e485e50
Author: Martin Mares <mj@ucw.cz>
Date: Mon Apr 5 20:17:59 1999 +0000
Added some new protocol hooks (look at the comments for better explanation):
make_tmp_attrs Convert inline attributes to ea_list
store_tmp_attrs Convert ea_list to inline attributes
import_control Pre-import decisions
commit 5056c559c4
Author: Martin Mares <mj@ucw.cz>
Date: Mon Apr 5 20:15:31 1999 +0000
Changed syntax of attaching filters to protocols to hopefully the final
version:
EXPORT <filter-spec> for outbound routes (i.e., those announced
by BIRD to the rest of the world).
IMPORT <filter-spec> for inbound routes (i.e., those imported
by BIRD from the rest of the world).
where <filter-spec> is one of:
ALL pass all routes
NONE drop all routes
FILTER <name> use named filter
FILTER { <filter> } use explicitly defined filter
For all protocols, the default is IMPORT ALL, EXPORT NONE. This includes
the kernel protocol, so that you need to add EXPORT ALL to get the previous
configuration of kernel syncer (as usually, see doc/bird.conf.example for
a bird.conf example :)).
Let's say RIP to this almost 19-years-old inconsistency. For now, if you
import a route, it is always from protocol to table. If you export a
route, it is always from table to protocol.
And they lived happily ever after.
no more warnings
No more warnings over me
And while it is being compiled all the log is black and white
Release BIRD now and then let it flee
(use the melody of well-known Oh Freedom!)
This is a fundamental change of an original (1999) concept of route
processing inside BIRD. During import/export, there was a temporary
ea_list created which was to be used instead of the another one inside
the route itself.
This led to some confusion, quirks, and strange filter code that handled
extended route attributes. Dropping it now.
The protocol interface has changed in an uniform way -- the
`struct ea_list *attrs` argument has been removed from store_tmp_attrs(),
import_control(), rt_notify() and get_route_info().
During route export, the receiving protocol often initialized route
metrics to default value in its import_control hook before export filter
was executed. This is inconsistent with the expectation that an export
filter would process the same route as one in the routing table and it
breaks setting these metrics before (e.g. for static routes directly in
static protocol).
The patch removes the initialization of route metrics in import_control
hook, the default values are already handled in rt_notify hook called
after export filters.
The patch also changed the behavior of OSPF to keep metrics when a route
is reannounced between OSPF instances (to be consistent with other
protocols) and the behavior when both ospf_metric1 and ospf_metric2
are specified (to have more expected behavior).
The old timer interface is still kept, but implemented by new timers. The
plan is to switch from the old inteface to the new interface, then clean
it up.
OSPFv3-AF can handle multiple topologies of diferent address families
(IPv4, IPv6, both unicast and multicast) using separate instances
distinguished by instance ID ranges.
Dropped struct mpnh and mpnh_*()
Now struct nexthop exists, nexthop_*(), and also included struct nexthop
into struct rta.
Also converted RTD_DEVICE and RTD_ROUTER to RTD_UNICAST. If it is needed
to distinguish between these two cases, RTD_DEVICE is equivalent to
IPA_ZERO(a->nh.gw), RTD_ROUTER is then IPA_NONZERO(a->nh.gw).
From now on, we also explicitely want C99 compatible compiler. We assume
that this 20-year norm should be known almost everywhere.
The patch adds support for channels, structures connecting protocols and
tables and handling most interactions between them. The documentation is
missing yet.
New data types net_addr and variants (in lib/net.h) describing
network addresses (prefix/pxlen). Modifications of FIB structures
to handle these data types and changing everything to use these
data types instead of prefix/pxlen pairs where possible.
The commit is WiP, some protocols are not yet updated (BGP, Kernel),
and the code contains some temporary scaffolding.
Comments are welcome.
The patch adds suport for specifying route attributes together with
static routes, e.g.:
route 10.1.1.0/24 via 10.0.0.1 { krt_advmss = 1200; ospf_metric1 = 100; };
