1 files changed, 44 insertions, 0 deletions
diff --git a/jstests/replsets/do_not_sync_from_stale_sync_source.js b/jstests/replsets/do_not_sync_from_stale_sync_source.js
new file mode 100644
index 00000000000..bf6957a0e06
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+++ b/jstests/replsets/do_not_sync_from_stale_sync_source.js
@@ -0,0 +1,44 @@
+/*
+ * This tests that nodes do not sync from other nodes that are behind them. The test sets up a
+ * 3-node replica set and then stops replication at one node so it starts to lag. The test then
+ * uses 'replSetSyncFrom' to force the up to date node to sync from the lagging node. After it
+ * receives its first batch, it errors saying that it cannot sync from a node behind it.
+ */
+
+(function() {
+    'use strict';
+
+    load("jstests/libs/check_log.js");
+    load("jstests/replsets/rslib.js");
+
+    var name = "do_not_sync_from_stale_sync_source";
+    var collName = "test.coll";
+
+    var rst = new ReplSetTest({
+        name: name,
+        nodes: [{}, {rsConfig: {priority: 0}}, {rsConfig: {priority: 0}}],
+        useBridge: true,
+        settings: {chainingAllowed: false}
+    });
+    var nodes = rst.startSet();
+    rst.initiate();
+
+    jsTestLog("Make sure node 0 is primary.");
+    assert.eq(nodes[0], rst.getPrimary());
+    // Wait for all data bearing nodes to get up to date.
+    assert.writeOK(nodes[0].getCollection(collName).insert(
+        {a: 0}, {writeConcern: {w: 3, wtimeout: rst.kDefaultTimeoutMS}}));
+
+    jsTestLog("Stop node 2 from syncing so it starts lagging.");
+    assert.commandWorked(nodes[2].getDB('admin').runCommand(
+        {configureFailPoint: 'stopReplProducer', mode: 'alwaysOn'}));
+    checkLog.contains(nodes[2], 'stopReplProducer fail point enabled');
+
+    jsTestLog("Do a write that replicates to [0,1].");
+    assert.writeOK(nodes[0].getCollection(collName).insert(
+        {a: 1}, {writeConcern: {w: 2, wtimeout: rst.kDefaultTimeoutMS}}));
+
+    jsTestLog("Tell node 1 to sync from node 0 which is now behind.");
+    assert.commandWorked(nodes[1].adminCommand({"replSetSyncFrom": nodes[0].host}));
+    checkLog.contains(nodes[1], "is not greater than our last fetched OpTime");
+}());