When the kernel filter is anything more sophisticated than FILTER_ACCEPT
or FILTER_REJECT, we should ensure that the old route being sent to the
kernel protocol is really what was sent there before. This fixes the old
misbehavior when an unfiltered old route was used.
The old code stored route verdicts and temporary routes directly in
rtable. The new code do not store received routes (it immediately
compares them with exported routes and resolves conflicts) and uses
internal bitmap to keep track of which routes were received and which
needs to be reinstalled.
By not putting 'invalid' temporary routes to rtable, we keep rtable
in consistent state, therefore scan no longer needs to be atomic
operation and could be splitted to multiple events.
Channel currently does not have independent pool and uses protocol pool,
which is freed when protocol changes state to down, while channel is
still in flushing. Move some some cleanup code to channel_do_flush()
so it is done before freeing of protocol pool.
Use a hierarchical bitmap in a routing table to assign ids to routes, and
then use bitmaps (indexed by route id) in channels to keep track whether
routes were exported. This avoids unreliable and inefficient re-evaluation
of filters for old routes in order to determine whether they were exported.
Continuation lines may use short form (with space instead of message
number), but this should not be done when previous line is final.
Thanks to Kenth Eriksson for the bugreport and analysis.
Underlying (IGP) route may lead to PtP link, in this case it does not
need gateway. Which is different than direct route without gateway.
When recursive (BGP) route uses PtP route, it should not use recursive
next hop as immediate next hop, while for direct routes it should.
The patch implements optional internal export table to a channel and
hooks it to BGP so it can be used as Adj-RIB-Out. When enabled, all
exported (post-filtered) routes are stored there. An export table can be
examined using e.g. 'show route export table bgp1.ipv4'.
Several BGP channel options (including 'next hop self') could be
reconfigured without session reset, with just route refeed/refresh.
The patch improves reconfiguration code to do it that way.
Protocol can have specified VRF, in such case it is restricted to a set
of ifaces associated with the VRF, otherwise it can use all interfaces.
The patch allows to specify VRF as 'default', in which case it is
restricted to a set of iface not associated with any VRF.
