Only create httpx ssl context once (#231)

* Only create httpx ssl context once

* Only create httpx ssl context once

* Only create httpx ssl context once

* Only create httpx ssl context once

* black

* black

src/amcrest/http.py

@@ -9,9 +9,12 @@
 #
 # vim:sw=4:ts=4:et
 import asyncio
+import contextlib
+from functools import lru_cache
 import logging
 import re
 import socket
+import ssl
 import threading
 from contextlib import asynccontextmanager
 from typing import AsyncIterator, Optional, Tuple, Union
@@ -46,13 +49,42 @@
 except AttributeError:
     pass
 
+
 TimeoutT = Union[Optional[float], Tuple[Optional[float], Optional[float]]]
 HttpxTimeoutT = Union[
     Optional[float],
     Tuple[Optional[float], Optional[float], Optional[float], Optional[float]],
 ]
 
 
+@lru_cache(maxsize=None)
+def create_default_ssl_context() -> ssl.SSLContext:
+    """Return an SSL context that verifies the server certificate."""
+    return ssl.create_default_context()
+
+
+@lru_cache(maxsize=None)
+def create_no_verify_ssl_context() -> ssl.SSLContext:
+    """Return an SSL context that does not verify the server certificate.
+    This is a copy of aiohttp's create_default_context() function, with the
+    ssl verify turned off and old SSL versions enabled.
+
+    https://github.com/aio-libs/aiohttp/blob/33953f110e97eecc707e1402daa8d543f38a189b/aiohttp/connector.py#L911
+    """
+    sslcontext = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+    sslcontext.check_hostname = False
+    sslcontext.verify_mode = ssl.CERT_NONE
+    # Allow all ciphers rather than only Python 3.10 default
+    sslcontext.set_ciphers("DEFAULT")
+    with contextlib.suppress(AttributeError):
+        # This only works for OpenSSL >= 1.0.0
+        sslcontext.options |= ssl.OP_NO_COMPRESSION
+    sslcontext.set_default_verify_paths()
+    # ssl.OP_LEGACY_SERVER_CONNECT is only available in Python 3.12a4+
+    sslcontext.options |= getattr(ssl, "OP_LEGACY_SERVER_CONNECT", 0x4)
+    return sslcontext
+
+
 class SOHTTPAdapter(HTTPAdapter):
     """HTTPAdapter with support for socket options."""
 
@@ -331,10 +363,15 @@ async def _async_command(
         else:
             httpx_timeout = timeout
 
+        if self._verify:
+            ssl_context = create_default_ssl_context()
+        else:
+            ssl_context = create_no_verify_ssl_context()
+
         async with httpx.AsyncClient(
             follow_redirects=True,
             auth=self._async_token,
-            verify=self._verify,
+            verify=ssl_context,
             timeout=httpx_timeout,
         ) as client:
             for loop in range(1, 2 + retries):