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https://issues.apache.org/jira/browse/CASSANDRA-21097?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
ConfX updated CASSANDRA-21097:
------------------------------
Summary: parseGossipInfo improper assumption might fail to parse gossip
output after a node restart (was: ClusterUtils.parseGossipInfo improper
assumption might fail to parse gossip output after a node restart)
> parseGossipInfo improper assumption might fail to parse gossip output after a
> node restart
> ------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-21097
> URL: https://issues.apache.org/jira/browse/CASSANDRA-21097
> Project: Apache Cassandra
> Issue Type: Bug
> Components: Test/dtest/java
> Reporter: ConfX
> Priority: Normal
>
> The `ClusterUtils.parseGossipInfo` method parses the gossip info output from
> `nodetool gossipinfo` by checking the line starts with "/". It expects
> endpoint addresses to start with "/".
> This assumption might be broken in the future with the following workflow,
> let me use an existing example to show you.
> In the existing test {*}JMXGetterCheckTest.testAllValidGetters(){*}, it call
> ALL JMX attributes including:
> {code:java}
> // FailureDetectorMBean methods that trigger hostname resolution:
> getAllEndpointStatesWithResolveIp() // resolveIp=true
> getAllEndpointStatesWithPortAndResolveIp() // resolveIp=true {code}
> These methods call `entry.getKey().getHostName()` on the gossip endpoint
> addresses (`FailureDetector.java:149`), which caches the hostname in the
> underlying `InetAddress` objects.
> Then:
> {code:java}
> 1. Test starts, cluster initializes
> └── Gossip endpoints created with InetAddress (hostname NOT resolved)
> └── InetAddress.toString() → "/127.0.0.1"
> 2. JMXGetterCheckTest calls all JMX getters
> └── Calls getAllEndpointStatesWithResolveIp()
> └── This calls getHostName() on gossip endpoint InetAddress objects
> └── Hostname "localhost" gets CACHED in the InetAddress objects
> 3. Node restart occurs
> └── Restart adapter calls awaitGossipSchemaMatch()
> └── This runs "nodetool gossipinfo" (resolveIp=false)
> └── But InetAddress.toString() now returns "localhost/127.0.0.1" (cached!)
> 4. parseGossipInfo() fails
> └── Checks: line.startsWith("/") → FALSE for "localhost/127.0.0.1"
> └── currentInstance remains null
> └── Objects.requireNonNull(currentInstance) → NPE! {code}
>
> Code that checks line start with "/":
> {code:java}
> private static Map<String, Map<String, String>> parseGossipInfo(String str)
> {
> Map<String, Map<String, String>> map = new HashMap<>();
> String[] lines = str.split("\n");
> String currentInstance = null;
> for (String line : lines)
> {
> if (line.startsWith("/")) // BUG: This condition is incorrect
> {
> // start of new instance
> currentInstance = line;
> continue;
> }
> Objects.requireNonNull(currentInstance); // NPE thrown here
> String[] kv = line.trim().split(":", 2);
> assert kv.length == 2 : "When splitting line '" + line + "' expected
> 2 parts but not true";
> Map<String, String> state = map.computeIfAbsent(currentInstance,
> ignore -> new HashMap<>());
> state.put(kv[0], kv[1]);
> }
> return map;
> } {code}
> Java's `InetAddress` caches hostname at the *object level.* The gossip
> `endpointStateMap` contains shared `InetAddressAndPort` objects. Once ANY
> code path calls `getHostName()` on these objects, all subsequent `toString()`
> calls return the hostname.
> h2. Stacktrace
> {code:java}
> java.lang.NullPointerException
> at java.base/java.util.Objects.requireNonNull(Objects.java:209)
> at
> org.apache.cassandra.distributed.shared.ClusterUtils.parseGossipInfo(ClusterUtils.java:691)
> at
> org.apache.cassandra.distributed.shared.ClusterUtils.gossipInfo(ClusterUtils.java:655)
> at
> org.apache.cassandra.distributed.shared.ClusterUtils.awaitGossip(ClusterUtils.java:554)
> at
> org.apache.cassandra.distributed.shared.ClusterUtils.awaitGossipSchemaMatch(ClusterUtils.java:600)
> {code}
> h2. A potential fix could be:
> Using regex to get:
>
> {code:java}
> // Pattern: optional hostname, then "/", then IP address
> private static final Pattern ENDPOINT_PATTERN =
> Pattern.compile("^[^\\s/]*/(\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3})(:\\d+)?$");
>
> ...
> // in the parseGossipInfo method:
> if (ENDPOINT_PATTERN.matcher(line).matches())
> {code}
>
> Matches:
> - /127.0.0.1 ✓
> - localhost/127.0.0.1 ✓
> - localhost/127.0.0.1:7000 ✓
>
> I'm happy to send a PR for this.
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