Support sni_hostname extension with SOCKS proxy. (#774)

* Handle `sni_hostname` extension when SOCKS proxy is activated.

* Add tests.

* Reformat the test.

* Run linting checks locally and reformat again.

* Update changelog and add a missing test.

* Update tests/_async/test_socks_proxy.py

* Update tests/_sync/test_socks_proxy.py

---------

Co-authored-by: Tom Christie <tom@tomchristie.com>

CHANGELOG.md

@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## Unreleased
 
 - Add support for HTTPS proxies. Currently only available for async. (#745)
+- Handle `sni_hostname` extension with SOCKS proxy. (#774)
 - Change the type of `Extensions` from `Mapping[Str, Any]` to `MutableMapping[Str, Any]`. (#762)
 - Handle HTTP/1.1 half-closed connections gracefully. (#641)
 - Drop Python 3.7 support. (#727)

httpcore/_async/socks_proxy.py

@@ -216,6 +216,7 @@ def __init__(
 
     async def handle_async_request(self, request: Request) -> Response:
         timeouts = request.extensions.get("timeout", {})
+        sni_hostname = request.extensions.get("sni_hostname", None)
         timeout = timeouts.get("connect", None)
 
         async with self._connect_lock:
@@ -258,7 +259,8 @@ async def handle_async_request(self, request: Request) -> Response:
 
                         kwargs = {
                             "ssl_context": ssl_context,
-                            "server_hostname": self._remote_origin.host.decode("ascii"),
+                            "server_hostname": sni_hostname
+                            or self._remote_origin.host.decode("ascii"),
                             "timeout": timeout,
                         }
                         async with Trace("start_tls", logger, request, kwargs) as trace:

httpcore/_sync/socks_proxy.py

@@ -216,6 +216,7 @@ def __init__(
 
     def handle_request(self, request: Request) -> Response:
         timeouts = request.extensions.get("timeout", {})
+        sni_hostname = request.extensions.get("sni_hostname", None)
         timeout = timeouts.get("connect", None)
 
         with self._connect_lock:
@@ -258,7 +259,8 @@ def handle_request(self, request: Request) -> Response:
 
                         kwargs = {
                             "ssl_context": ssl_context,
-                            "server_hostname": self._remote_origin.host.decode("ascii"),
+                            "server_hostname": sni_hostname
+                            or self._remote_origin.host.decode("ascii"),
                             "timeout": timeout,
                         }
                         with Trace("start_tls", logger, request, kwargs) as trace: