Github user afine commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/432#discussion_r156781040
--- Diff:
src/java/test/org/apache/zookeeper/server/quorum/QuorumPeerMainTest.java ---
@@ -335,6 +336,100 @@ public void testHighestZxidJoinLate() throws
Exception {
output[0], 2);
}
+ /**
+ * This test validates that if a quorum member determines that it is
leader without the support of the rest of the
+ * quorum (the other members do not believe it to be the leader) it
will stop attempting to lead and become a follower.
+ *
+ * @throws IOException
+ * @throws InterruptedException
+ */
+ @Test
+ public void testElectionFraud() throws IOException,
InterruptedException {
+ // capture QuorumPeer logging
+ Layout layout =
Logger.getRootLogger().getAppender("CONSOLE").getLayout();
+ ByteArrayOutputStream os = new ByteArrayOutputStream();
+ WriterAppender appender = new WriterAppender(layout, os);
+ appender.setThreshold(Level.INFO);
+ Logger qlogger = Logger.getLogger(QuorumPeer.class);
+ qlogger.addAppender(appender);
+
+ int numServers = 3;
+
+ // used for assertions later
+ boolean foundLeading = false;
+ boolean foundLooking = false;
+ boolean foundFollowing = false;
+
+ try {
+ // spin up a quorum, we use a small ticktime to make the test
run faster
+ Servers servers = LaunchServers(numServers, 500);
+
+ // find the leader
+ int trueLeader = -1;
+ for (int i = 0; i < numServers; i++) {
+ if (servers.mt[i].main.quorumPeer.leader != null) {
+ trueLeader = i;
+ }
+ }
+ Assert.assertTrue("There should be a leader", trueLeader >= 0);
+
+ // find a follower
+ int falseLeader = (trueLeader + 1) % numServers;
+
Assert.assertTrue(servers.mt[falseLeader].main.quorumPeer.follower != null);
+
+ // to keep the quorum peer running and force it to go into the
looking state, we kill leader election
+ // and close the connection to the leader
+ servers.mt[falseLeader].main.quorumPeer.electionAlg.shutdown();
+
servers.mt[falseLeader].main.quorumPeer.follower.getSocket().close();
+
+ // wait for the falseLeader to disconnect
+ waitForOne(servers.zk[falseLeader], States.CONNECTING);
+
+ // convince falseLeader that it is the leader
+
servers.mt[falseLeader].main.quorumPeer.setPeerState(QuorumPeer.ServerState.LEADING);
+
+ // provide time for the falseleader to realize no followers have
connected
+ // (this is twice the timeout used in Leader#getEpochToPropose)
+ Thread.sleep(2 *
servers.mt[falseLeader].main.quorumPeer.initLimit *
servers.mt[falseLeader].main.quorumPeer.tickTime);
+
+ // Restart leader election
+ servers.mt[falseLeader].main.quorumPeer.startLeaderElection();
--- End diff --
Stopping and starting leader election is necessary here to prevent a race
condition. It is possible that after the server is disconnected from the leader
it becomes a follower before the test hits
`servers.mt[falseLeader].main.quorumPeer.setPeerState(QuorumPeer.ServerState.LEADING);`
and falseLeader will never try to `lead`, defeating the purpose of the test.
---
