Add ALPN extension to client SSL Context (#10156)

CHANGES/10156.feature.rst

@@ -0,0 +1,3 @@
+Enabled ALPN on default SSL contexts. This improves compatibility with some
+proxies which don't work without this extension.
+-- by :user:`Cycloctane`.

CONTRIBUTORS.txt

@@ -376,6 +376,7 @@ William S.
 Wilson Ong
 wouter bolsterlee
 Xavier Halloran
+Xi Rui
 Xiang Li
 Yang Zhou
 Yannick Koechlin

aiohttp/connector.py

@@ -772,14 +772,16 @@ def _make_ssl_context(verified: bool) -> SSLContext:
         # No ssl support
         return None  # type: ignore[unreachable]
     if verified:
-        return ssl.create_default_context()
-    sslcontext = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
-    sslcontext.options |= ssl.OP_NO_SSLv2
-    sslcontext.options |= ssl.OP_NO_SSLv3
-    sslcontext.check_hostname = False
-    sslcontext.verify_mode = ssl.CERT_NONE
-    sslcontext.options |= ssl.OP_NO_COMPRESSION
-    sslcontext.set_default_verify_paths()
+        sslcontext = ssl.create_default_context()
+    else:
+        sslcontext = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        sslcontext.options |= ssl.OP_NO_SSLv2
+        sslcontext.options |= ssl.OP_NO_SSLv3
+        sslcontext.check_hostname = False
+        sslcontext.verify_mode = ssl.CERT_NONE
+        sslcontext.options |= ssl.OP_NO_COMPRESSION
+        sslcontext.set_default_verify_paths()
+    sslcontext.set_alpn_protocols(("http/1.1",))
     return sslcontext
 
 

tests/test_client_functional.py

@@ -632,6 +632,30 @@ async def handler(request: web.Request) -> web.Response:
     assert txt == "Test message"
 
 
+async def test_ssl_client_alpn(
+    aiohttp_server: AiohttpServer,
+    aiohttp_client: AiohttpClient,
+    ssl_ctx: ssl.SSLContext,
+) -> None:
+
+    async def handler(request: web.Request) -> web.Response:
+        assert request.transport is not None
+        sslobj = request.transport.get_extra_info("ssl_object")
+        return web.Response(text=sslobj.selected_alpn_protocol())
+
+    app = web.Application()
+    app.router.add_route("GET", "/", handler)
+    ssl_ctx.set_alpn_protocols(("http/1.1",))
+    server = await aiohttp_server(app, ssl=ssl_ctx)
+
+    connector = aiohttp.TCPConnector(ssl=False)
+    client = await aiohttp_client(server, connector=connector)
+    resp = await client.get("/")
+    assert resp.status == 200
+    txt = await resp.text()
+    assert txt == "http/1.1"
+
+
 async def test_tcp_connector_fingerprint_ok(
     aiohttp_server: AiohttpServer,
     aiohttp_client: AiohttpClient,