ipv6/nib: bugfix of 6CO length checking #17850
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fabian18
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| DEBUG("nib: received 6CO of invalid length (%u), must be %u " | ||
| "or wasn't delivered by RA." | ||
| "\n", | ||
| assert(icmpv6->type == ICMPV6_RTR_ADV); |
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That's from a received package, right?
Since there is always the possibility to receive garbage, we can't trigger an assert on a malformed packet, otherwise a bad node can bring other, perfectly fine behaving nodes down by sending packets that trigger asserts.
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Ah yes. Then I would drop the check for Router Advertisement completely, because we decide when we handle the Context Option (call the function) and we only handle it in an RA as it should be.
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That´s why I found the check unnecessary.
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So if the assert ever fires, we would have a misuse of the function rather than an evil node sending us garbage :)
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Contribution description
The condition to check the length of an 6LoWPAN-ND Context Option was wrong.
If the prefix length > 64 it must be 3 (MAX), if it is less or equal 64 it must be 2 (MIN).
RFC6775 section 4.2
Testing procedure
See #17803 (comment).
At least
nib: received 6CO of invalid length (3), must be 3 or wasn't delivered by RA.does not show up anymore.Issues/PRs references