From 2e2cf5b40473bbe2fdf1b0771fc28e174603a1c0 Mon Sep 17 00:00:00 2001
From: Richard Schwab <gitrichardschwab-7a2qxq42kj@central-intelligence.agency>
Date: Sun, 8 May 2022 22:19:52 +0200
Subject: [PATCH] Add `implicit_tls` connect arg to support non-standard
 implicit TLS connections, such as Google Cloud SQL

fixes #757
---
 CHANGES.txt            |  5 +++++
 aiomysql/connection.py | 14 ++++++++++----
 docs/connection.rst    |  7 ++++++-
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index c717378f..68523f1f 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,6 +1,11 @@
 Changes
 -------
 
+next (unreleased)
+^^^^^^^^^^^^^^^^^
+
+* Add `implicit_tls` connect arg to support non-standard implicit TLS connections, such as Google Cloud SQL #757
+
 0.1.1 (2022-05-08)
 ^^^^^^^^^^^^^^^^^^
 
diff --git a/aiomysql/connection.py b/aiomysql/connection.py
index 022315a9..26be319d 100644
--- a/aiomysql/connection.py
+++ b/aiomysql/connection.py
@@ -53,7 +53,7 @@ def connect(host="localhost", user=None, password="",
             connect_timeout=None, read_default_group=None,
             autocommit=False, echo=False,
             local_infile=False, loop=None, ssl=None, auth_plugin='',
-            program_name='', server_public_key=None):
+            program_name='', server_public_key=None, implicit_tls=False):
     """See connections.Connection.__init__() for information about
     defaults."""
     coro = _connect(host=host, user=user, password=password, db=db,
@@ -66,7 +66,8 @@ def connect(host="localhost", user=None, password="",
                     read_default_group=read_default_group,
                     autocommit=autocommit, echo=echo,
                     local_infile=local_infile, loop=loop, ssl=ssl,
-                    auth_plugin=auth_plugin, program_name=program_name)
+                    auth_plugin=auth_plugin, program_name=program_name,
+                    implicit_tls=implicit_tls)
     return _ConnectionContextManager(coro)
 
 
@@ -142,7 +143,7 @@ def __init__(self, host="localhost", user=None, password="",
                  connect_timeout=None, read_default_group=None,
                  autocommit=False, echo=False,
                  local_infile=False, loop=None, ssl=None, auth_plugin='',
-                 program_name='', server_public_key=None):
+                 program_name='', server_public_key=None, implicit_tls=False):
         """
         Establish a connection to the MySQL database. Accepts several
         arguments:
@@ -184,6 +185,9 @@ def __init__(self, host="localhost", user=None, password="",
             handshaking with MySQL. (omitted by default)
         :param server_public_key: SHA256 authentication plugin public
             key value.
+        :param implicit_tls: Establish TLS immediately, skipping non-TLS
+            preamble before upgrading to TLS.
+            (default: False)
         :param loop: asyncio loop
         """
         self._loop = loop or asyncio.get_event_loop()
@@ -218,6 +222,7 @@ def __init__(self, host="localhost", user=None, password="",
         self._auth_plugin_used = ""
         self._secure = False
         self.server_public_key = server_public_key
+        self._implicit_tls = implicit_tls
         self.salt = None
 
         from . import __version__
@@ -738,7 +743,8 @@ async def _request_authentication(self):
                                 charset_id, b'')
 
         if self._ssl_context and self.server_capabilities & CLIENT.SSL:
-            self.write_packet(data_init)
+            if not self._implicit_tls:
+                self.write_packet(data_init)
 
             # Stop sending events to data_received
             self._writer.transport.pause_reading()
diff --git a/docs/connection.rst b/docs/connection.rst
index 49936e01..de23a0cd 100644
--- a/docs/connection.rst
+++ b/docs/connection.rst
@@ -47,7 +47,7 @@ Example::
             connect_timeout=None, read_default_group=None,
             autocommit=False, echo=False
             ssl=None, auth_plugin='', program_name='',
-            server_public_key=None, loop=None)
+            server_public_key=None, loop=None, implicit_tls=False)
 
     A :ref:`coroutine <coroutine>` that connects to MySQL.
 
@@ -93,6 +93,11 @@ Example::
             ``sys.argv[0]`` is no longer passed by default
     :param server_public_key: SHA256 authenticaiton plugin public key value.
     :param loop: asyncio event loop instance or ``None`` for default one.
+    :param implicit_tls: Establish TLS immediately, skipping non-TLS
+        preamble before upgrading to TLS.
+        (default: False)
+
+        .. versionadded:: 0.2
     :returns: :class:`Connection` instance.