Fix sending from "default" expose in flow-filter #1227
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We'll need to add some processing specific to some of the local expose objects in a follow-up commit, so we need to make the distinction on a per-expose basis rather than use a flat map of the prefixes. Signed-off-by: Quentin Monnet <qmo@qmon.net>
We recently added support for "default" expose blocks used as a fallback destination for packets from the VPC when the destination IP matches no other exposed prefixes. From the "default" block we deduce information about the destination VPC, and about whether the packet has a valid destination. But we forgot to use it for the reverse check: when a packet is emitted from a VPC, from behind a "default" block, its source address should always be considered as valid. This is not the case! So if we have VPC A and B peered together, and VPC B exposing a "default" block, VPC A can send packets to VPC B through this block, but all replies from VPC B are dropped. This commit fixes the issue by adding a "default source" connection information object to the context for the flow-filter stage, in the per-source-VPC-discriminant table. This information is used to validate the destination and retrieve the destination VPC when a packet is emitted from behind a "default" expose block. Also add unit tests to validate the behaviour. Fixes: d081eb6 ("feat(flow-filter): Add support for "default" destination VpcExpose") Signed-off-by: Quentin Monnet <qmo@qmon.net>
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Fredi-raspall
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Jan 22, 2026
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Jan 22, 2026
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Clarified, thanks!
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We recently added support for "default" expose blocks used as a fallback destination for packets from the VPC when the destination IP matches no other exposed prefixes. From the "default" block we deduce information about the destination VPC, and about whether the packet has a valid destination. But we forgot to use it for the reverse check: when a packet is emitted from a VPC, from behind a "default" block, its source address should always be considered as valid. This is not the case! So if we have VPC A and B peered together, and VPC B exposing a "default" block, VPC A can send packets to VPC B through this block, but all replies from VPC B are dropped.
This PR fixes the issue by adding a "default source" connection information object to the context for the flow-filter stage, in the per-source-VPC-discriminant table. This information is used to validate the destination and retrieve the destination VPC when a packet is emitted from behind a "default" expose block.