FEAT: Change default ODBC driver to v18 with v17 fallback and logging

mssql/base.py

@@ -4,11 +4,14 @@
 """
 MS SQL Server database backend for Django.
 """
+import logging
 import os
 import re
 import time
 import struct
 import datetime
+
+logger = logging.getLogger('django.db.backends')
 from decimal import Decimal
 from uuid import UUID
 
@@ -279,7 +282,8 @@ def get_connection_params(self):
             conn_params['NAME'] = 'master'
         return conn_params
 
-    def get_new_connection(self, conn_params):
+    def _build_connection_string(self, conn_params, driver):
+        """Build ODBC connection string for the given driver."""
         database = conn_params['NAME']
         host = conn_params.get('HOST', 'localhost')
         user = conn_params.get('USER', None)
@@ -288,7 +292,6 @@ def get_new_connection(self, conn_params):
         trusted_connection = conn_params.get('Trusted_Connection', 'yes')
 
         options = conn_params.get('OPTIONS', {})
-        driver = options.get('driver', 'ODBC Driver 17 for SQL Server')
         dsn = options.get('dsn', None)
         options_extra_params = options.get('extra_params', '')
 
@@ -345,6 +348,23 @@ def get_new_connection(self, conn_params):
         if options.get('extra_params', None):
             connstr += ';' + options['extra_params']
 
+        return connstr
+
+    def _is_driver_not_found_error(self, exception):
+        """Check if the exception indicates a driver not found error."""
+        error_msg = str(exception).lower()
+        return (
+            "can't open lib" in error_msg or
+            "data source name not found" in error_msg or
+            "driver not found" in error_msg or
+            "specified driver could not be loaded" in error_msg
+        )
+
+    def get_new_connection(self, conn_params):
+        options = conn_params.get('OPTIONS', {})
+        driver = options.get('driver', 'ODBC Driver 18 for SQL Server')
+        driver_explicitly_set = 'driver' in options
+
         unicode_results = options.get('unicode_results', False)
         timeout = options.get('connection_timeout', 0)
         retries = options.get('connection_retries', 5)
@@ -353,6 +373,8 @@ def get_new_connection(self, conn_params):
         setencoding = options.get('setencoding', None)
         setdecoding = options.get('setdecoding', None)
 
+        connstr = self._build_connection_string(conn_params, driver)
+
         conn = None
         retry_count = 0
         need_to_retry = False
@@ -364,10 +386,39 @@ def get_new_connection(self, conn_params):
             args['attrs_before'] = {
                 1256: prepare_token_for_odbc(conn_params['TOKEN'])
             }
+
+        # Track if we've attempted fallback to v17
+        attempted_v17_fallback = False
+
         while conn is None:
             try:
                 conn = Database.connect(connstr, **args)
             except Exception as e:
+                # If driver not explicitly set and v18 failed with driver not found,
+                # try falling back to v17
+                if (not driver_explicitly_set and
+                    not attempted_v17_fallback and
+                    self._is_driver_not_found_error(e) and
+                    'ODBC Driver 18' in driver):
+
+                    attempted_v17_fallback = True
+                    driver = 'ODBC Driver 17 for SQL Server'
+                    connstr = self._build_connection_string(conn_params, driver)
+
+                    logger.warning(
+                        "ODBC Driver 18 for SQL Server not found. "
+                        "Falling back to ODBC Driver 17 for SQL Server. "
+                        "SECURITY WARNING: ODBC Driver 18 has more secure defaults. "
+                        "To resolve this warning, consider one of the following options "
+                        "(in order of recommendation): "
+                        "(1) Install ODBC Driver 18 and configure a valid certificate on the server, "
+                        "(2) Install ODBC Driver 18 and set 'TrustServerCertificate': 'yes' in OPTIONS extra_params "
+                        "if you trust the server, "
+                        "(3) Explicitly set 'driver': 'ODBC Driver 17 for SQL Server' in OPTIONS "
+                        "to suppress this warning."
+                    )
+                    continue
+
                 for error_number in self._transient_error_numbers:
                     if error_number in e.args[1]:
                         if error_number in e.args[1] and retry_count < retries:

setup.py

@@ -49,6 +49,9 @@
         'pyodbc>=3.0',
         'pytz',
     ],
+    extras_require={
+        'test': ['unittest-xml-reporting>=3.2.0'],
+    },
     package_data={'mssql': ['regex_clr.dll']},
     classifiers=CLASSIFIERS,
     keywords='django',