Check username validity in the FakeAuthPolicyClient

chromeos/dbus/fake_auth_policy_client.cc

Index: chromeos/dbus/fake_auth_policy_client.cc
diff --git a/chromeos/dbus/fake_auth_policy_client.cc b/chromeos/dbus/fake_auth_policy_client.cc
index f37f1ea53bc88d6aa576485db9d67fb310e6978b..e97aca0972915221c63098cec4c22944e12b9d98 100644
--- a/chromeos/dbus/fake_auth_policy_client.cc
+++ b/chromeos/dbus/fake_auth_policy_client.cc
@@ -10,6 +10,7 @@
 #include "base/location.h"
 #include "base/md5.h"
 #include "base/path_service.h"
+#include "base/strings/string_split.h"
 #include "base/task_scheduler/post_task.h"
 #include "chrome/browser/chromeos/policy/proto/chrome_device_policy.pb.h"
 #include "chromeos/chromeos_paths.h"
@@ -65,6 +66,13 @@ void FakeAuthPolicyClient::JoinAdDomain(const std::string& machine_name,
                                         const std::string& user_principal_name,
                                         int password_fd,
                                         const JoinCallback& callback) {
+  std::vector<std::string> parts = base::SplitString(
+      user_principal_name, "@", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+  if (parts.size() != 2 || parts[0].empty() || parts[1].empty()) {
+    callback.Run(authpolicy::ERROR_PARSE_UPN_FAILED);
+    return;
+  }
+
   callback.Run(authpolicy::ERROR_NONE);
 }