libnetwork/ipam: refactor prefix-overlap checks #46755
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
I am finally convinced that, given two netip.Prefix values a and b, the
expression
a.Contains(b.Addr()) || b.Contains(a.Addr())
is functionally equivalent to
a.Overlaps(b)
The (netip.Prefix).Contains method works by masking the address with the
prefix's mask and testing whether the remaining most-significant bits
are equal to the same bits in the prefix. The (netip.Prefix).Overlaps
method works by masking the longer prefix to the length of the shorter
prefix and testing whether the remaining most-significant bits are
equal. This is equivalent to
shorterPrefix.Contains(longerPrefix.Addr()), therefore applying Contains
symmetrically to two prefixes will always yield the same result as
applying Overlaps to the two prefixes in either order.
Signed-off-by: Cory Snider <csnider@mirantis.com>
neersighted
approved these changes
Nov 2, 2023
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
I am finally convinced that, given two netip.Prefix values a and b, the expression
is functionally equivalent to
The
(netip.Prefix).Containsmethod works by masking the address with the prefix's mask and testing whether the remaining most-significant bits are equal to the same bits in the prefix. The(netip.Prefix).Overlapsmethod works by masking the longer prefix to the length of the shorter prefix and testing whether the remaining most-significant bits are equal. This is equivalent toshorterPrefix.Contains(longerPrefix.Addr()), therefore applyingContainssymmetrically to two prefixes will always yield the same result as applyingOverlapsto the two prefixes in either order.- What I did
- How I did it
- How to verify it
- Description for the changelog
- A picture of a cute animal (not mandatory but encouraged)