1 files changed, 31 insertions, 0 deletions
diff --git a/synapse/config/validators.py b/synapse/config/validators.py
new file mode 100644
index 0000000000..2faae0cf4a
--- /dev/null
+++ b/synapse/config/validators.py
@@ -0,0 +1,31 @@
+import re
+from typing import Type
+
+from pydantic import BaseModel
+from pydantic.fields import ModelField
+
+
+def string_length_between(lower: int, upper: int):
+    def validator(cls: Type[BaseModel], value: str, field: ModelField) -> str:
+        print(f"validate {lower=} {upper=} {value=}")
+        if lower <= len(value) <= upper:
+            print("ok")
+            return value
+        print("bad")
+        raise ValueError(
+            f"{field.name} must be between {lower} and {upper} characters long"
+        )
+
+    return validator
+
+
+def string_contains_characters(charset: str):
+    def validator(cls: Type[BaseModel], value: str, field: ModelField) -> str:
+        pattern = f"^[{charset}]*$"
+        if re.match(pattern, value):
+            return value
+        raise ValueError(
+            f"{field.name} must be only contain the characters {charset}"
+        )
+
+    return validator