addrmgr: mark IPv6 zero addresses as non-routable#2474
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Roasbeef merged 1 commit intobtcsuite:masterfrom Mar 24, 2026
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addrmgr: mark IPv6 zero addresses as non-routable#2474Roasbeef merged 1 commit intobtcsuite:masterfrom
Roasbeef merged 1 commit intobtcsuite:masterfrom
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In this commit, we fix `IsRoutable` to correctly reject IPv6 addresses whose first 16-bit group is zero (i.e., in the `0000::/16` reserved block per RFC 4291). Differential fuzzing between btcd and Bitcoin Core revealed that addresses like `0:9881:8181:8181:fe00:a:9e:9801` were slipping through as routable when they shouldn't be. We add a new `zero6Net` (`0000::/16`) definition alongside the existing `zero4Net`, and introduce an `IsZero` helper that checks both. The /16 prefix width is intentional: the broader /8 reservation would incorrectly catch allocated sub-ranges like `0064:ff9b::/96` (RFC 6052, NAT64). We also carve out an exception for RFC 6145 translated IPv4 addresses (`::ffff:0:0:0/96`), which live within `0000::/16` but are valid for routing. Test coverage includes the original bug report address, various zero-prefix IPv6 addresses, the RFC 6145 exclusion, and corresponding `GroupKey` entries to confirm they land in the "unroutable" bucket. Fixes btcsuite#2431
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Resolved some issues I found locally, pushed directly to the branch. |
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Summary
zero6Netdefinition for IPv6 0::/8 block (reserved per RFC 4291)IsZerofunction that checks both IPv4 and IPv6 zero address blocksIsRoutableto reject zero addresses, matching Bitcoin Core behaviorTest plan
0::1and similar addresses in 0::/8 are now rejected by IsRoutableCloses #2431
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