Commit b4438e40 authored Jan 30, 2019 by Ondrej Zajicek (work)

Nest: Prevent withdraws from propagation back to source protocol

The earlier fix loosen conditions for not running filters on old
route when deciding about route propagation to a protocol to avoid
issues with ghost routes in some race conditions.

Unfortunately, the fix also caused back-propagation of withdraws. For
regular updates, back-propagation is prevented in import_control hooks,
but these are not called on withdraws. For them, import_control hooks
are called on old routes instead, changing (old, NULL) notification
to (NULL, NULL), which is ignored. By not calling export processing
in some cases, the withdraw is not ignored and is back-propagated.

This patch fixes that by contract conditions so the earlier fix is not
applied to back-propagated updates.

parent ccb37330

nest/rt-table.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -434,7 +434,8 @@ rt_notify_basic(struct announce_hook ah, net net, rte new0, rte old0, int re
		if (new)
		new = export_filter(ah, new, &new_free, &tmpa, 0);

		if (old && !(refeed \|\| (old->lastmod <= ah->last_out_filter_change)))
		if (old && !(refeed \|\| ((old->lastmod <= ah->last_out_filter_change) &&
		(p != old->sender->proto))))
		old = export_filter(ah, old, &old_free, NULL, 1);

		if (!new && !old)

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