SERVER-20651 do not allow mongos connect to mongod if mongod does not support COMMAND protocol

2 files changed, 18 insertions, 0 deletions

diff --git a/src/mongo/rpc/protocol.cpp b/src/mongo/rpc/protocol.cpp
index 5bff4b05e4f..3c3cafb6479 100644
--- a/src/mongo/rpc/protocol.cpp
+++ b/src/mongo/rpc/protocol.cpp
@@ -151,5 +151,18 @@ bool supportsWireVersionForOpCommandInMongod(int minWireVersion, int maxWireVers
         (maxWireVersion >= WireVersion::FIND_COMMAND);
 }
 
+ProtocolSet computeProtocolSet(int minWireVersion, int maxWireVersion) {
+    ProtocolSet result = supports::kNone;
+    if (minWireVersion <= maxWireVersion) {
+        if (maxWireVersion >= WireVersion::FIND_COMMAND) {
+            result |= supports::kOpCommandOnly;
+        }
+        if (minWireVersion <= WireVersion::RELEASE_2_4_AND_BEFORE) {
+            result |= supports::kOpQueryOnly;
+        }
+    }
+    return result;
+}
+
 }  // namespace rpc
 }  // namespace mongo
diff --git a/src/mongo/rpc/protocol.h b/src/mongo/rpc/protocol.h
index 4efb5e0b833..643351106e0 100644
--- a/src/mongo/rpc/protocol.h
+++ b/src/mongo/rpc/protocol.h
@@ -106,5 +106,10 @@ StatusWith<ProtocolSet> parseProtocolSetFromIsMasterReply(const BSONObj& isMaste
  */
 bool supportsWireVersionForOpCommandInMongod(int minWireVersion, int maxWireVersion);
 
+/**
+  * Computes supported protocols from wire versions.
+  */
+ProtocolSet computeProtocolSet(int minWireVersion, int maxWireVersion);
+
 }  // namespace rpc
 }  // namespace mongo