SERVER-45396 Fix the 'me' field in isMaster responses when using splithorizon

(cherry picked from commit a1a1e4f0c14ab71a5fc8bc7913af25571089b65f)

2 files changed, 22 insertions, 3 deletions

diff --git a/jstests/ssl/repl_ssl_split_horizon.js b/jstests/ssl/repl_ssl_split_horizon.js
index 19e2648df6f..fe4f4272098 100644
--- a/jstests/ssl/repl_ssl_split_horizon.js
+++ b/jstests/ssl/repl_ssl_split_horizon.js
@@ -108,6 +108,11 @@ replTest.initiate(config);
 
 var checkExpectedHorizon = function(url, memberIndex, expectedHostname) {
     // Run isMaster in the shell and check that we get the expected hostname back
+    const assertion = (memberIndex === "me")
+        ? ("assert(db.runCommand({isMaster: 1})['me'] == '" + expectedHostname + "')")
+        : ("assert(db.runCommand({isMaster: 1})['hosts'][" + memberIndex + "] == '" +
+           expectedHostname + "')");
+
     var argv = [
         'env',
         "HOSTALIASES=" + hostsFile,
@@ -115,8 +120,7 @@ var checkExpectedHorizon = function(url, memberIndex, expectedHostname) {
         './mongo',
         url,
         '--eval',
-        ("assert(db.runCommand({isMaster: 1})['hosts'][" + memberIndex + "] == '" +
-         expectedHostname + "')")
+        assertion
     ];
     return runMongoProgram(...argv);
 };
@@ -127,6 +131,9 @@ jsTestLog(`URL without horizon: ${defaultURL}`);
 assert.eq(checkExpectedHorizon(defaultURL, 0, node0localHostname),
           0,
           "localhost does not return horizon");
+assert.eq(checkExpectedHorizon(defaultURL, "me", node0localHostname),
+          0,
+          "localhost does not return horizon");
 assert.eq(checkExpectedHorizon(defaultURL, 1, node1localHostname),
           0,
           "localhost does not return horizon");
@@ -137,6 +144,9 @@ jsTestLog(`URL with horizon: ${horizonURL}`);
 assert.eq(checkExpectedHorizon(horizonURL, 0, node0horizonHostname),
           0,
           "does not return horizon as expected");
+assert.eq(checkExpectedHorizon(horizonURL, "me", node0horizonHostname),
+          0,
+          "does not return horizon as expected");
 assert.eq(checkExpectedHorizon(horizonURL, 1, node1horizonHostname),
           0,
           "does not return horizon as expected");
@@ -148,6 +158,9 @@ jsTestLog(`URL with horizon: ${horizonMissingURL}`);
 assert.eq(checkExpectedHorizon(horizonMissingURL, 0, node0localHostname),
           0,
           "does not return localhost as expected");
+assert.eq(checkExpectedHorizon(horizonMissingURL, "me", node0localHostname),
+          0,
+          "does not return localhost as expected");
 assert.eq(checkExpectedHorizon(horizonMissingURL, 1, node1localHostname),
           0,
           "does not return localhost as expected");
@@ -166,6 +179,9 @@ jsTestLog(`URL with horizon: ${horizonMissingURL}`);
 assert.eq(checkExpectedHorizon(horizonMissingURL, 0, node0horizonMissingHostname),
           0,
           "does not return horizon as expected");
+assert.eq(checkExpectedHorizon(horizonMissingURL, "me", node0horizonMissingHostname),
+          0,
+          "does not return horizon as expected");
 assert.eq(checkExpectedHorizon(horizonMissingURL, 1, node1horizonMissingHostname),
           0,
           "does not return horizon as expected");
@@ -187,6 +203,9 @@ jsTestLog(`URL with horizon using different port: ${horizonDifferentPortURL}`);
 assert.eq(checkExpectedHorizon(horizonDifferentPortURL, 0, node0horizonHostnameDifferentPort),
           0,
           "does not return horizon as expected");
+assert.eq(checkExpectedHorizon(horizonDifferentPortURL, "me", node0horizonHostnameDifferentPort),
+          0,
+          "does not return horizon as expected");
 assert.eq(checkExpectedHorizon(horizonDifferentPortURL, 1, node1horizonHostnameDifferentPort),
           0,
           "does not return horizon as expected");
diff --git a/src/mongo/db/repl/topology_coordinator.cpp b/src/mongo/db/repl/topology_coordinator.cpp
index 8dd4927061b..8325303d6e0 100644
--- a/src/mongo/db/repl/topology_coordinator.cpp
+++ b/src/mongo/db/repl/topology_coordinator.cpp
@@ -1759,7 +1759,7 @@ void TopologyCoordinator::fillIsMasterForReplSet(IsMasterResponse* const respons
             response->addTag(tagKey, tagConfig.getTagValue(*tag));
         }
     }
-    response->setMe(selfConfig.getHostAndPort());
+    response->setMe(selfConfig.getHostAndPort(horizon));
     if (_iAmPrimary()) {
         response->setElectionId(_electionId);
     }