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The SLIST (essentially `fctx->finds`, forwarders and dual-stack alternatives aside) can have duplicate server addresses when multiple in-domain nameservers share the same IP addresses: sub.example. NS ns1.sub.example. sub.example. NS ns2.sub.example. ns1.sub.example. A 1.2.3.4 ns1.sub.example. A 5.6.7.8 ns2.sub.example. A 1.2.3.4 ns2.sub.example. A 5.6.7.8 If both 1.2.3.4 and 5.6.7.8 fail to return a valid answer, the resolver would query each address twice. The problem is fixed by replacing the two-phase server selection (sort each find list by SRTT, sort finds by head SRTT) with a single linear scan in nextaddress() that finds the lowest-SRTT unmarked, non-duplicate address across all find lists. The old approach had a correctness bug: after sorting, the resolver picked the next address from the "current" find list rather than globally. For example, with find lists [1, 15, 26] and [3, 4, 5], the second pick would be SRTT 15 instead of the correct SRTT 3. The new approach is both simpler and correct: each call to nextaddress() walks all addresses, skips marked and duplicate entries, and returns the one with the lowest SRTT. While this walk is repeated for each server attempt, it operates on a small bounded list and is negligible compared to the network I/O of querying the server. (cherry picked from commit b1c5856a3764b4025e93f8baf06c45c8fa029752) |
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| bind9 | ||
| dns | ||
| irs | ||
| isc | ||
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| isccfg | ||
| ns | ||
| .gitignore | ||
| Makefile.am | ||