SERVER-25393 Disallow mongos making connections to older versions

1 files changed, 19 insertions, 3 deletions

diff --git a/src/mongo/rpc/protocol.h b/src/mongo/rpc/protocol.h
index 45280849c29..6ac205ccc2f 100644
--- a/src/mongo/rpc/protocol.h
+++ b/src/mongo/rpc/protocol.h
@@ -33,6 +33,7 @@
 #include <type_traits>
 
 #include "mongo/base/status_with.h"
+#include "mongo/db/wire_version.h"
 
 namespace mongo {
 class BSONObj;
@@ -108,19 +109,34 @@ StatusWith<StringData> toString(ProtocolSet protocols);
 StatusWith<ProtocolSet> parseProtocolSet(StringData repr);
 
 /**
+ * Validates client and server wire version. The server is returned from isMaster, and the client is
+ * from WireSpec.instance().
+ */
+Status validateWireVersion(const WireVersionInfo client, const WireVersionInfo server);
+
+/**
+ * Struct to pass around information about protocol set and wire version.
+ */
+struct ProtocolSetAndWireVersionInfo {
+    ProtocolSet protocolSet;
+    WireVersionInfo version;
+};
+
+/**
  * Determines the ProtocolSet of a remote server from an isMaster reply.
  */
-StatusWith<ProtocolSet> parseProtocolSetFromIsMasterReply(const BSONObj& isMasterReply);
+StatusWith<ProtocolSetAndWireVersionInfo> parseProtocolSetFromIsMasterReply(
+    const BSONObj& isMasterReply);
 
 /**
  * Returns true if wire version supports OP_COMMAND in mongod (not mongos).
  */
-bool supportsWireVersionForOpCommandInMongod(int minWireVersion, int maxWireVersion);
+bool supportsWireVersionForOpCommandInMongod(const WireVersionInfo version);
 
 /**
   * Computes supported protocols from wire versions.
   */
-ProtocolSet computeProtocolSet(int minWireVersion, int maxWireVersion);
+ProtocolSet computeProtocolSet(const WireVersionInfo version);
 
 }  // namespace rpc
 }  // namespace mongo