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https://issues.apache.org/jira/browse/HADOOP-20072?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Siyao Meng updated HADOOP-20072:
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Status: Patch Available (was: Open)
> TableMapping never matches IPv6 entries written in compressed form
> ------------------------------------------------------------------
>
> Key: HADOOP-20072
> URL: https://issues.apache.org/jira/browse/HADOOP-20072
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: net
> Reporter: Siyao Meng
> Assignee: Siyao Meng
> Priority: Major
> Labels: pull-request-available
>
> {{CachedDNSToSwitchMapping#resolve}} normalizes every name with
> {{NetUtils.normalizeHostName}}, which returns {{InetAddress#getHostAddress}}.
> For IPv6 that is the full form without zero compression, for example
> {{2001:db8:0:0:0:0:0:10}}. {{TableMapping}} then looks the name up with an
> exact string match ({{RawTableMapping#resolve}}), and its keys are kept
> exactly as written in the table file.
> So an entry in the usual compressed form ([RFC
> 5952|https://datatracker.ietf.org/doc/html/rfc5952]), such as
> {{2001:db8::10}}, never matches, whichever form the caller passes. The node
> quietly falls back to {{/default-rack}}. Only the full form works.
> h3. Reproduction (3.4.3)
> Table file:
> {noformat}
> 2001:db8::10 /rack1
> 10.0.0.5 /rack2
> {noformat}
> {code:java}
> tableMapping.resolve(Arrays.asList("2001:db8::10", "2001:db8:0:0:0:0:0:10",
> "10.0.0.5"));
> // [/default-rack, /default-rack, /rack2]
> {code}
> With {{2001:db8:0:0:0:0:0:10 /rack1}} in the file instead, the first two
> resolve to {{/rack1}}.
> h3. Impact
> Rack awareness for nodes registered by IPv6 address: HDFS datanodes, and
> Ozone datanodes and clients (SCM and OM resolve through the same mapping).
> {{ScriptBasedMapping}} passes the same full form to the topology script, so
> scripts have to expect it too.
> h3. Proposal
> When loading the table in {{RawTableMapping#load}}, normalize keys that are
> IP literals to the same form the lookup uses (for example
> {{InetAddresses.forString(key).getHostAddress()}}), without DNS lookups.
> Leave other keys as they are. Add a test with compressed and full-form IPv6
> entries.
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