HDFS-10685: libhdfs++: return explicit error when non-secured client connects to secured server. Contributed by Kai Jiang.

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/include/hdfspp/status.h

@@ -43,6 +43,7 @@ class Status {
   static Status Exception(const char *exception_class_name, const char *exception_details);
   static Status Error(const char *error_message);
   static Status AuthenticationFailed();
+  static Status AuthenticationFailed(const char *msg);
   static Status Canceled();
   static Status PathNotFound(const char *msg);
   static Status InvalidOffset(const char *msg);

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/lib/common/status.cc

@@ -131,7 +131,16 @@ Status Status::Error(const char *error_message) {
 }
 
 Status Status::AuthenticationFailed() {
-  return Status(kAuthenticationFailed, "Authentication failed");
+  return Status::AuthenticationFailed(nullptr);
+}
+
+Status Status::AuthenticationFailed(const char *msg) {
+  std::string formatted = "AuthenticationFailed";
+  if(msg) {
+    formatted += ": ";
+    formatted += msg;
+  }
+  return Status(kAuthenticationFailed, formatted.c_str());
 }
 
 Status Status::Canceled() {

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/lib/rpc/cyrus_sasl_engine.cc

@@ -91,7 +91,7 @@ Status make_status(int rc) {
   if (rc != SASL_OK &&
       rc != SASL_CONTINUE &&
       rc != SASL_INTERACT) {
-     return Status::Error(errStr(rc).c_str());
+     return Status::AuthenticationFailed(errStr(rc).c_str());
   }
   return Status::OK();
 }

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/lib/rpc/rpc_connection.cc

@@ -293,7 +293,11 @@ Status RpcConnection::HandleRpcResponse(std::shared_ptr<Response> response) {
   auto req = RemoveFromRunningQueue(h.callid());
   if (!req) {
     LOG_WARN(kRPC, << "RPC response with Unknown call id " << h.callid());
-    return Status::Error("Rpc response with unknown call id");
+    if((int32_t)h.callid() == RpcEngine::kCallIdSasl) {
+      return Status::AuthenticationFailed("You have an unsecured client connecting to a secured server");
+    } else {
+      return Status::Error("Rpc response with unknown call id");
+    }
   }
 
   Status status;