1 files changed, 18 insertions, 0 deletions
diff --git a/oauthlib/oauth2/rfc6749/grant_types/base.py b/oauthlib/oauth2/rfc6749/grant_types/base.py
index a64f168..ca343a1 100644
--- a/oauthlib/oauth2/rfc6749/grant_types/base.py
+++ b/oauthlib/oauth2/rfc6749/grant_types/base.py
@@ -10,6 +10,7 @@ from oauthlib.oauth2.rfc6749 import errors, utils
 from oauthlib.uri_validate import is_absolute_uri
 
 from ..request_validator import RequestValidator
+from ..utils import is_secure_transport
 
 log = logging.getLogger(__name__)
 
@@ -248,3 +249,20 @@ class GrantTypeBase:
                 raise errors.MissingRedirectURIError(request=request)
             if not is_absolute_uri(request.redirect_uri):
                 raise errors.InvalidRedirectURIError(request=request)
+
+    def _create_cors_headers(self, request):
+        """If CORS is allowed, create the appropriate headers."""
+        if 'origin' not in request.headers:
+            return {}
+
+        origin = request.headers['origin']
+        if not is_secure_transport(origin):
+            log.debug('Origin "%s" is not HTTPS, CORS not allowed.', origin)
+            return {}
+        elif not self.request_validator.is_origin_allowed(
+            request.client_id, origin, request):
+            log.debug('Invalid origin "%s", CORS not allowed.', origin)
+            return {}
+        else:
+            log.debug('Valid origin "%s", injecting CORS headers.', origin)
+            return {'Access-Control-Allow-Origin': origin}