fix: enter unreachable when discarding HBH Option with multicast destination address #996
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It was previously possible to enter an unreachable path when the HBH option type was 0b11 and the destination address was multicast. This is now fixed in the interface. I also changed the way an HBH option type is parsed. The option type is only 2 bits, meaning that we can't have an unknown state.
jordens
approved these changes
Sep 27, 2024
Dirbaio
reviewed
Sep 27, 2024
| Ipv6OptionFailureType::DiscardSendUnicast => { | ||
| if !ipv6_repr.dst_addr.is_multicast() { | ||
| return HopByHopResponse::Discard(param_problem()); | ||
| } |
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we still have to return here if the sender is multicast, to discard the packet, right?
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Yes, indeed, I misread this in the RFC. I thought only the option needs to be discarded, but like you say, the full packet needs to be discarded, without sending an ICMP parameter problem back.
Discard the packet if the Hop-by-Hop header type is 0b11 and the packet destination address is multicast.
Dirbaio
approved these changes
Sep 27, 2024
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It was previously possible to enter an unreachable path when the HBH option type was 0b11 and the destination address was multicast. This is now fixed in the interface.
I also changed the way an HBH option type is parsed. Only the 2 highest order bits indicate what action must be taken, meaning that we can't have an unknown state.