Add extra error checking and logging to Software Secure callback

lms/djangoapps/verify_student/views.py

@@ -170,7 +170,17 @@ def results_callback(request):
     verified to be who they said they are.
     """
     body = request.body
-    body_dict = json.loads(body)
+
+    try:
+        body_dict = json.loads(body)
+    except ValueError:
+        log.exception("Invalid JSON received from Software Secure:\n\n{}\n".format(body))
+        return HttpResponseBadRequest("Invalid JSON. Received:\n\n{}".format(body))
+
+    if not isinstance(body_dict, dict):
+        log.error("Reply from Software Secure is not a dict:\n\n{}\n".format(body))
+        return HttpResponseBadRequest("JSON should be dict. Received:\n\n{}".format(body))
+
     headers = {
         "Authorization": request.META.get("HTTP_AUTHORIZATION", ""),
         "Date": request.META.get("HTTP_DATE", "")