SERVER-20748 Handle epoch mismatch explicitly in cluster find command

2 files changed, 11 insertions, 2 deletions

diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index ec130328bef..bd3d95e7295 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -424,8 +424,9 @@ void _generateErrorResponse(OperationContext* txn,
             static_cast<const SendStaleConfigException&>(exception);
         replyBuilder->setCommandReply(scex.toStatus(),
                                       BSON("ns" << scex.getns() << "vReceived"
-                                                << scex.getVersionReceived().toBSON() << "vWanted"
-                                                << scex.getVersionWanted().toBSON()));
+                                                << BSONArray(scex.getVersionReceived().toBSON())
+                                                << "vWanted"
+                                                << BSONArray(scex.getVersionWanted().toBSON())));
     } else {
         replyBuilder->setCommandReply(exception.toStatus());
     }
diff --git a/src/mongo/db/query/cursor_response.cpp b/src/mongo/db/query/cursor_response.cpp
index 3c86439f622..2954da683c9 100644
--- a/src/mongo/db/query/cursor_response.cpp
+++ b/src/mongo/db/query/cursor_response.cpp
@@ -34,6 +34,7 @@
 
 #include "mongo/bson/bsontypes.h"
 #include "mongo/rpc/get_status_from_command_result.h"
+#include "mongo/s/chunk_version.h"
 
 namespace mongo {
 
@@ -97,6 +98,13 @@ CursorResponse& CursorResponse::operator=(CursorResponse&& other) {
 StatusWith<CursorResponse> CursorResponse::parseFromBSON(const BSONObj& cmdResponse) {
     Status cmdStatus = getStatusFromCommandResult(cmdResponse);
     if (!cmdStatus.isOK()) {
+        if (ErrorCodes::isStaleShardingError(cmdStatus.code())) {
+            auto vWanted = ChunkVersion::fromBSON(cmdResponse, "vWanted");
+            auto vReceived = ChunkVersion::fromBSON(cmdResponse, "vReceived");
+            if (!vWanted.hasEqualEpoch(vReceived)) {
+                return Status(ErrorCodes::StaleEpoch, cmdStatus.reason());
+            }
+        }
         return cmdStatus;
     }