PYTHON-4575 Remove hostname length check

Author: aclark4life

pymongo/asynchronous/srv_resolver.py

@@ -96,8 +96,6 @@ def __init__(
         except Exception:
             raise ConfigurationError(_INVALID_HOST_MSG % (fqdn,)) from None
         self.__slen = len(self.__plist)
-        if self.__slen < 2:
-            raise ConfigurationError(_INVALID_HOST_MSG % (fqdn,))
 
     async def get_options(self) -> Optional[str]:
         from dns import resolver

pymongo/synchronous/srv_resolver.py

@@ -96,8 +96,6 @@ def __init__(
         except Exception:
             raise ConfigurationError(_INVALID_HOST_MSG % (fqdn,)) from None
         self.__slen = len(self.__plist)
-        if self.__slen < 2:
-            raise ConfigurationError(_INVALID_HOST_MSG % (fqdn,))
 
     def get_options(self) -> Optional[str]:
         from dns import resolver

test/test_uri_parser.py

@@ -24,6 +24,7 @@
 sys.path[0:0] = [""]
 
 from test import unittest
+from unittest.mock import patch
 
 from bson.binary import JAVA_LEGACY
 from pymongo import ReadPreference
@@ -553,6 +554,11 @@ def test_port_with_whitespace(self):
         with self.assertRaisesRegex(ValueError, r"Port contains whitespace character: '\\n'"):
             parse_uri("mongodb://localhost:27\n017")
 
+    def test_allow_srv_hosts_with_fewer_than_three_dot_separated_parts(self):
+        with patch("dns.resolver.resolve"):
+            parse_uri("mongodb+srv://localhost/")
+            parse_uri("mongodb+srv://mongo.local/")
+
 
 if __name__ == "__main__":
     unittest.main()