Merge branch 'master' into develop

9 files changed, 90 insertions, 57 deletions

diff --git a/CHANGES.md b/CHANGES.md
index f869674ace..49d388aa06 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -56,6 +56,26 @@
 * Bump ulid from 1.1.2 to 1.1.3. ([\#17442](https://github.com/element-hq/synapse/issues/17442))
 * Bump zipp from 3.15.0 to 3.19.1. ([\#17427](https://github.com/element-hq/synapse/issues/17427))
 
+# Synapse 1.111.1 (2024-07-30)
+
+This security release is to update our locked dependency on Twisted to 24.7.0rc1, which includes a security fix for [CVE-2024-41671 / GHSA-c8m8-j448-xjx7: Disordered HTTP pipeline response in twisted.web, again](https://github.com/twisted/twisted/security/advisories/GHSA-c8m8-j448-xjx7).
+
+This issue means that, if multiple HTTP requests are pipelined in the same TCP connection, Synapse can send responses to the wrong HTTP request.
+If a reverse proxy was configured to use HTTP pipelining, this could result in responses being sent to the wrong user, severely harming confidentiality.
+
+With that said, despite being a high severity issue, **we consider it unlikely that Synapse installations will be affected**.
+The use of HTTP pipelining in this fashion would cause worse performance for clients (request-response latencies would be increased as users' responses would be artificially blocked behind other users' slow requests). Further, Nginx and Haproxy, two common reverse proxies, do not appear to support configuring their upstreams to use HTTP pipelining and thus would not be affected. For both of these reasons, we consider it unlikely that a Synapse deployment would be set up in such a configuration.
+
+Despite that, we cannot rule out that some installations may exist with this unusual setup and so we are releasing this security update today.
+
+**pip users:** Note that by default, upgrading Synapse using pip will not automatically upgrade Twisted. **Please manually install the new version of Twisted** using `pip install Twisted==24.7.0rc1`. Note also that even the `--upgrade-strategy=eager` flag to `pip install -U matrix-synapse` will not upgrade Twisted to a patched version because it is only a release candidate at this time.
+
+
+### Internal Changes
+
+- Upgrade locked dependency on Twisted to 24.7.0rc1. ([\#17502](https://github.com/element-hq/synapse/issues/17502))
+
+
 # Synapse 1.111.0 (2024-07-16)
 
 No significant changes since 1.111.0rc2.
diff --git a/debian/changelog b/debian/changelog
index 5209b9f5fd..a35e973b75 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -4,6 +4,12 @@ matrix-synapse-py3 (1.112.0~rc1) stable; urgency=medium
 
  -- Synapse Packaging team <packages@matrix.org>  Tue, 23 Jul 2024 08:58:55 -0600
 
+matrix-synapse-py3 (1.111.1) stable; urgency=medium
+
+  * New Synapse release 1.111.1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Tue, 30 Jul 2024 16:13:52 +0100
+
 matrix-synapse-py3 (1.111.0) stable; urgency=medium
 
   * New Synapse release 1.111.0.
diff --git a/poetry.lock b/poetry.lock
index 417f6850b8..e4d5097724 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 1.8.3 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.5.1 and should not be changed by hand.
 
 [[package]]
 name = "annotated-types"
@@ -821,18 +821,21 @@ testing = ["flake8 (<5)", "pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-chec
 
 [[package]]
 name = "incremental"
-version = "22.10.0"
-description = "\"A small library that versions your Python projects.\""
+version = "24.7.2"
+description = "A small library that versions your Python projects."
 optional = false
-python-versions = "*"
+python-versions = ">=3.8"
 files = [
-    {file = "incremental-22.10.0-py2.py3-none-any.whl", hash = "sha256:b864a1f30885ee72c5ac2835a761b8fe8aa9c28b9395cacf27286602688d3e51"},
-    {file = "incremental-22.10.0.tar.gz", hash = "sha256:912feeb5e0f7e0188e6f42241d2f450002e11bbc0937c65865045854c24c0bd0"},
+    {file = "incremental-24.7.2-py3-none-any.whl", hash = "sha256:8cb2c3431530bec48ad70513931a760f446ad6c25e8333ca5d95e24b0ed7b8fe"},
+    {file = "incremental-24.7.2.tar.gz", hash = "sha256:fb4f1d47ee60efe87d4f6f0ebb5f70b9760db2b2574c59c8e8912be4ebd464c9"},
 ]
 
+[package.dependencies]
+setuptools = ">=61.0"
+tomli = {version = "*", markers = "python_version < \"3.11\""}
+
 [package.extras]
-mypy = ["click (>=6.0)", "mypy (==0.812)", "twisted (>=16.4.0)"]
-scripts = ["click (>=6.0)", "twisted (>=16.4.0)"]
+scripts = ["click (>=6.0)"]
 
 [[package]]
 name = "isort"
@@ -2711,13 +2714,13 @@ urllib3 = ">=1.26.0"
 
 [[package]]
 name = "twisted"
-version = "24.3.0"
+version = "24.7.0rc1"
 description = "An asynchronous networking framework written in Python"
 optional = false
 python-versions = ">=3.8.0"
 files = [
-    {file = "twisted-24.3.0-py3-none-any.whl", hash = "sha256:039f2e6a49ab5108abd94de187fa92377abe5985c7a72d68d0ad266ba19eae63"},
-    {file = "twisted-24.3.0.tar.gz", hash = "sha256:6b38b6ece7296b5e122c9eb17da2eeab3d98a198f50ca9efd00fb03e5b4fd4ae"},
+    {file = "twisted-24.7.0rc1-py3-none-any.whl", hash = "sha256:f37d6656fe4e2871fab29d8952ae90bd6ca8b48a9e4dfa1b348f4cd62e6ba0bb"},
+    {file = "twisted-24.7.0rc1.tar.gz", hash = "sha256:bbc4a2193ca34cfa32f626300746698a6d70fcd77d9c0b79a664c347e39634fc"},
 ]
 
 [package.dependencies]
@@ -2726,48 +2729,26 @@ automat = ">=0.8.0"
 constantly = ">=15.1"
 hyperlink = ">=17.1.1"
 idna = {version = ">=2.4", optional = true, markers = "extra == \"tls\""}
-incremental = ">=22.10.0"
+incremental = ">=24.7.0"
 pyopenssl = {version = ">=21.0.0", optional = true, markers = "extra == \"tls\""}
 service-identity = {version = ">=18.1.0", optional = true, markers = "extra == \"tls\""}
-twisted-iocpsupport = {version = ">=1.0.2,<2", markers = "platform_system == \"Windows\""}
 typing-extensions = ">=4.2.0"
 zope-interface = ">=5"
 
 [package.extras]
-all-non-platform = ["twisted[conch,http2,serial,test,tls]", "twisted[conch,http2,serial,test,tls]"]
+all-non-platform = ["appdirs (>=1.4.0)", "appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "bcrypt (>=3.1.3)", "cryptography (>=3.3)", "cryptography (>=3.3)", "cython-test-exception-raiser (>=1.0.2,<2)", "cython-test-exception-raiser (>=1.0.2,<2)", "h2 (>=3.0,<5.0)", "h2 (>=3.0,<5.0)", "hypothesis (>=6.56)", "hypothesis (>=6.56)", "idna (>=2.4)", "idna (>=2.4)", "priority (>=1.1.0,<2.0)", "priority (>=1.1.0,<2.0)", "pyhamcrest (>=2)", "pyhamcrest (>=2)", "pyopenssl (>=21.0.0)", "pyopenssl (>=21.0.0)", "pyserial (>=3.0)", "pyserial (>=3.0)", "pywin32 (!=226)", "pywin32 (!=226)", "service-identity (>=18.1.0)", "service-identity (>=18.1.0)"]
 conch = ["appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "cryptography (>=3.3)"]
-dev = ["coverage (>=6b1,<7)", "pyflakes (>=2.2,<3.0)", "python-subunit (>=1.4,<2.0)", "twisted[dev-release]", "twistedchecker (>=0.7,<1.0)"]
+dev = ["coverage (>=7.5,<8.0)", "cython-test-exception-raiser (>=1.0.2,<2)", "hypothesis (>=6.56)", "pydoctor (>=23.9.0,<23.10.0)", "pyflakes (>=2.2,<3.0)", "pyhamcrest (>=2)", "python-subunit (>=1.4,<2.0)", "sphinx (>=6,<7)", "sphinx-rtd-theme (>=1.3,<2.0)", "towncrier (>=23.6,<24.0)", "twistedchecker (>=0.7,<1.0)"]
 dev-release = ["pydoctor (>=23.9.0,<23.10.0)", "pydoctor (>=23.9.0,<23.10.0)", "sphinx (>=6,<7)", "sphinx (>=6,<7)", "sphinx-rtd-theme (>=1.3,<2.0)", "sphinx-rtd-theme (>=1.3,<2.0)", "towncrier (>=23.6,<24.0)", "towncrier (>=23.6,<24.0)"]
-gtk-platform = ["pygobject", "pygobject", "twisted[all-non-platform]", "twisted[all-non-platform]"]
+gtk-platform = ["appdirs (>=1.4.0)", "appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "bcrypt (>=3.1.3)", "cryptography (>=3.3)", "cryptography (>=3.3)", "cython-test-exception-raiser (>=1.0.2,<2)", "cython-test-exception-raiser (>=1.0.2,<2)", "h2 (>=3.0,<5.0)", "h2 (>=3.0,<5.0)", "hypothesis (>=6.56)", "hypothesis (>=6.56)", "idna (>=2.4)", "idna (>=2.4)", "priority (>=1.1.0,<2.0)", "priority (>=1.1.0,<2.0)", "pygobject", "pygobject", "pyhamcrest (>=2)", "pyhamcrest (>=2)", "pyopenssl (>=21.0.0)", "pyopenssl (>=21.0.0)", "pyserial (>=3.0)", "pyserial (>=3.0)", "pywin32 (!=226)", "pywin32 (!=226)", "service-identity (>=18.1.0)", "service-identity (>=18.1.0)"]
 http2 = ["h2 (>=3.0,<5.0)", "priority (>=1.1.0,<2.0)"]
-macos-platform = ["pyobjc-core", "pyobjc-core", "pyobjc-framework-cfnetwork", "pyobjc-framework-cfnetwork", "pyobjc-framework-cocoa", "pyobjc-framework-cocoa", "twisted[all-non-platform]", "twisted[all-non-platform]"]
-mypy = ["mypy (>=1.8,<2.0)", "mypy-zope (>=1.0.3,<1.1.0)", "twisted[all-non-platform,dev]", "types-pyopenssl", "types-setuptools"]
-osx-platform = ["twisted[macos-platform]", "twisted[macos-platform]"]
+macos-platform = ["appdirs (>=1.4.0)", "appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "bcrypt (>=3.1.3)", "cryptography (>=3.3)", "cryptography (>=3.3)", "cython-test-exception-raiser (>=1.0.2,<2)", "cython-test-exception-raiser (>=1.0.2,<2)", "h2 (>=3.0,<5.0)", "h2 (>=3.0,<5.0)", "hypothesis (>=6.56)", "hypothesis (>=6.56)", "idna (>=2.4)", "idna (>=2.4)", "priority (>=1.1.0,<2.0)", "priority (>=1.1.0,<2.0)", "pyhamcrest (>=2)", "pyhamcrest (>=2)", "pyobjc-core", "pyobjc-core", "pyobjc-framework-cfnetwork", "pyobjc-framework-cfnetwork", "pyobjc-framework-cocoa", "pyobjc-framework-cocoa", "pyopenssl (>=21.0.0)", "pyopenssl (>=21.0.0)", "pyserial (>=3.0)", "pyserial (>=3.0)", "pywin32 (!=226)", "pywin32 (!=226)", "service-identity (>=18.1.0)", "service-identity (>=18.1.0)"]
+mypy = ["appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "coverage (>=7.5,<8.0)", "cryptography (>=3.3)", "cython-test-exception-raiser (>=1.0.2,<2)", "h2 (>=3.0,<5.0)", "hypothesis (>=6.56)", "idna (>=2.4)", "mypy (>=1.8,<2.0)", "mypy-zope (>=1.0.3,<1.1.0)", "priority (>=1.1.0,<2.0)", "pydoctor (>=23.9.0,<23.10.0)", "pyflakes (>=2.2,<3.0)", "pyhamcrest (>=2)", "pyopenssl (>=21.0.0)", "pyserial (>=3.0)", "python-subunit (>=1.4,<2.0)", "pywin32 (!=226)", "service-identity (>=18.1.0)", "sphinx (>=6,<7)", "sphinx-rtd-theme (>=1.3,<2.0)", "towncrier (>=23.6,<24.0)", "twistedchecker (>=0.7,<1.0)", "types-pyopenssl", "types-setuptools"]
+osx-platform = ["appdirs (>=1.4.0)", "appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "bcrypt (>=3.1.3)", "cryptography (>=3.3)", "cryptography (>=3.3)", "cython-test-exception-raiser (>=1.0.2,<2)", "cython-test-exception-raiser (>=1.0.2,<2)", "h2 (>=3.0,<5.0)", "h2 (>=3.0,<5.0)", "hypothesis (>=6.56)", "hypothesis (>=6.56)", "idna (>=2.4)", "idna (>=2.4)", "priority (>=1.1.0,<2.0)", "priority (>=1.1.0,<2.0)", "pyhamcrest (>=2)", "pyhamcrest (>=2)", "pyobjc-core", "pyobjc-core", "pyobjc-framework-cfnetwork", "pyobjc-framework-cfnetwork", "pyobjc-framework-cocoa", "pyobjc-framework-cocoa", "pyopenssl (>=21.0.0)", "pyopenssl (>=21.0.0)", "pyserial (>=3.0)", "pyserial (>=3.0)", "pywin32 (!=226)", "pywin32 (!=226)", "service-identity (>=18.1.0)", "service-identity (>=18.1.0)"]
 serial = ["pyserial (>=3.0)", "pywin32 (!=226)"]
 test = ["cython-test-exception-raiser (>=1.0.2,<2)", "hypothesis (>=6.56)", "pyhamcrest (>=2)"]
 tls = ["idna (>=2.4)", "pyopenssl (>=21.0.0)", "service-identity (>=18.1.0)"]
-windows-platform = ["pywin32 (!=226)", "pywin32 (!=226)", "twisted[all-non-platform]", "twisted[all-non-platform]"]
-
-[[package]]
-name = "twisted-iocpsupport"
-version = "1.0.2"
-description = "An extension for use in the twisted I/O Completion Ports reactor."
-optional = false
-python-versions = "*"
-files = [
-    {file = "twisted-iocpsupport-1.0.2.tar.gz", hash = "sha256:72068b206ee809c9c596b57b5287259ea41ddb4774d86725b19f35bf56aa32a9"},
-    {file = "twisted_iocpsupport-1.0.2-cp310-cp310-win32.whl", hash = "sha256:985c06a33f5c0dae92c71a036d1ea63872ee86a21dd9b01e1f287486f15524b4"},
-    {file = "twisted_iocpsupport-1.0.2-cp310-cp310-win_amd64.whl", hash = "sha256:81b3abe3527b367da0220482820cb12a16c661672b7bcfcde328902890d63323"},
-    {file = "twisted_iocpsupport-1.0.2-cp36-cp36m-win32.whl", hash = "sha256:9dbb8823b49f06d4de52721b47de4d3b3026064ef4788ce62b1a21c57c3fff6f"},
-    {file = "twisted_iocpsupport-1.0.2-cp36-cp36m-win_amd64.whl", hash = "sha256:b9fed67cf0f951573f06d560ac2f10f2a4bbdc6697770113a2fc396ea2cb2565"},
-    {file = "twisted_iocpsupport-1.0.2-cp37-cp37m-win32.whl", hash = "sha256:b76b4eed9b27fd63ddb0877efdd2d15835fdcb6baa745cb85b66e5d016ac2878"},
-    {file = "twisted_iocpsupport-1.0.2-cp37-cp37m-win_amd64.whl", hash = "sha256:851b3735ca7e8102e661872390e3bce88f8901bece95c25a0c8bb9ecb8a23d32"},
-    {file = "twisted_iocpsupport-1.0.2-cp38-cp38-win32.whl", hash = "sha256:bf4133139d77fc706d8f572e6b7d82871d82ec7ef25d685c2351bdacfb701415"},
-    {file = "twisted_iocpsupport-1.0.2-cp38-cp38-win_amd64.whl", hash = "sha256:306becd6e22ab6e8e4f36b6bdafd9c92e867c98a5ce517b27fdd27760ee7ae41"},
-    {file = "twisted_iocpsupport-1.0.2-cp39-cp39-win32.whl", hash = "sha256:3c61742cb0bc6c1ac117a7e5f422c129832f0c295af49e01d8a6066df8cfc04d"},
-    {file = "twisted_iocpsupport-1.0.2-cp39-cp39-win_amd64.whl", hash = "sha256:b435857b9efcbfc12f8c326ef0383f26416272260455bbca2cd8d8eca470c546"},
-    {file = "twisted_iocpsupport-1.0.2-pp37-pypy37_pp73-win_amd64.whl", hash = "sha256:7d972cfa8439bdcb35a7be78b7ef86d73b34b808c74be56dfa785c8a93b851bf"},
-]
+windows-platform = ["appdirs (>=1.4.0)", "appdirs (>=1.4.0)", "bcrypt (>=3.1.3)", "bcrypt (>=3.1.3)", "cryptography (>=3.3)", "cryptography (>=3.3)", "cython-test-exception-raiser (>=1.0.2,<2)", "cython-test-exception-raiser (>=1.0.2,<2)", "h2 (>=3.0,<5.0)", "h2 (>=3.0,<5.0)", "hypothesis (>=6.56)", "hypothesis (>=6.56)", "idna (>=2.4)", "idna (>=2.4)", "priority (>=1.1.0,<2.0)", "priority (>=1.1.0,<2.0)", "pyhamcrest (>=2)", "pyhamcrest (>=2)", "pyopenssl (>=21.0.0)", "pyopenssl (>=21.0.0)", "pyserial (>=3.0)", "pyserial (>=3.0)", "pywin32 (!=226)", "pywin32 (!=226)", "pywin32 (!=226)", "pywin32 (!=226)", "service-identity (>=18.1.0)", "service-identity (>=18.1.0)", "twisted-iocpsupport (>=1.0.2)", "twisted-iocpsupport (>=1.0.2)"]
 
 [[package]]
 name = "txredisapi"
diff --git a/synapse/http/proxy.py b/synapse/http/proxy.py
index 5b5ded757b..97aa429e7d 100644
--- a/synapse/http/proxy.py
+++ b/synapse/http/proxy.py
@@ -62,6 +62,15 @@ HOP_BY_HOP_HEADERS = {
     "Upgrade",
 }
 
+if hasattr(Headers, "_canonicalNameCaps"):
+    # Twisted < 24.7.0rc1
+    _canonicalHeaderName = Headers()._canonicalNameCaps  # type: ignore[attr-defined]
+else:
+    # Twisted >= 24.7.0rc1
+    # But note that `_encodeName` still exists on prior versions,
+    # it just encodes differently
+    _canonicalHeaderName = Headers()._encodeName
+
 
 def parse_connection_header_value(
     connection_header_value: Optional[bytes],
@@ -85,11 +94,10 @@ def parse_connection_header_value(
         The set of header names that should not be copied over from the remote response.
         The keys are capitalized in canonical capitalization.
     """
-    headers = Headers()
     extra_headers_to_remove: Set[str] = set()
     if connection_header_value:
         extra_headers_to_remove = {
-            headers._canonicalNameCaps(connection_option.strip()).decode("ascii")
+            _canonicalHeaderName(connection_option.strip()).decode("ascii")
             for connection_option in connection_header_value.split(b",")
         }
 
diff --git a/synapse/http/server.py b/synapse/http/server.py
index 211795dc39..0d0c610b28 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -74,6 +74,7 @@ from synapse.api.errors import (
 from synapse.config.homeserver import HomeServerConfig
 from synapse.logging.context import defer_to_thread, preserve_fn, run_in_background
 from synapse.logging.opentracing import active_span, start_active_span, trace_servlet
+from synapse.types import ISynapseReactor
 from synapse.util import json_encoder
 from synapse.util.caches import intern_dict
 from synapse.util.cancellation import is_function_cancellable
@@ -868,7 +869,8 @@ async def _async_write_json_to_request_in_thread(
 
     with start_active_span("encode_json_response"):
         span = active_span()
-        json_str = await defer_to_thread(request.reactor, encode, span)
+        reactor: ISynapseReactor = request.reactor  # type: ignore
+        json_str = await defer_to_thread(reactor, encode, span)
 
     _write_bytes_to_request(request, json_str)
 
diff --git a/synapse/http/site.py b/synapse/http/site.py
index a5b5780679..af169ba51e 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -683,7 +683,7 @@ class SynapseSite(ProxySite):
         self.access_logger = logging.getLogger(logger_name)
         self.server_version_string = server_version_string.encode("ascii")
 
-    def log(self, request: SynapseRequest) -> None:
+    def log(self, request: SynapseRequest) -> None:  # type: ignore[override]
         pass
 
 
diff --git a/tests/rest/client/test_login.py b/tests/rest/client/test_login.py
index 3fb77fd9dd..2b1e44381b 100644
--- a/tests/rest/client/test_login.py
+++ b/tests/rest/client/test_login.py
@@ -969,9 +969,8 @@ class CASTestCase(unittest.HomeserverTestCase):
         # Test that the response is HTML.
         self.assertEqual(channel.code, 200, channel.result)
         content_type_header_value = ""
-        for header in channel.result.get("headers", []):
-            if header[0] == b"Content-Type":
-                content_type_header_value = header[1].decode("utf8")
+        for header in channel.headers.getRawHeaders("Content-Type", []):
+            content_type_header_value = header
 
         self.assertTrue(content_type_header_value.startswith("text/html"))
 
diff --git a/tests/server.py b/tests/server.py
index 85602e6953..3e377585ce 100644
--- a/tests/server.py
+++ b/tests/server.py
@@ -198,17 +198,35 @@ class FakeChannel:
     def headers(self) -> Headers:
         if not self.result:
             raise Exception("No result yet.")
-        h = Headers()
-        for i in self.result["headers"]:
-            h.addRawHeader(*i)
+
+        h = self.result["headers"]
+        assert isinstance(h, Headers)
         return h
 
     def writeHeaders(
-        self, version: bytes, code: bytes, reason: bytes, headers: Headers
+        self,
+        version: bytes,
+        code: bytes,
+        reason: bytes,
+        headers: Union[Headers, List[Tuple[bytes, bytes]]],
     ) -> None:
         self.result["version"] = version
         self.result["code"] = code
         self.result["reason"] = reason
+
+        if isinstance(headers, list):
+            # Support prior to Twisted 24.7.0rc1
+            new_headers = Headers()
+            for k, v in headers:
+                assert isinstance(k, bytes), f"key is not of type bytes: {k!r}"
+                assert isinstance(v, bytes), f"value is not of type bytes: {v!r}"
+                new_headers.addRawHeader(k, v)
+            headers = new_headers
+
+        assert isinstance(
+            headers, Headers
+        ), f"headers are of the wrong type: {headers!r}"
+
         self.result["headers"] = headers
 
     def write(self, data: bytes) -> None:
diff --git a/tests/test_server.py b/tests/test_server.py
index 0910ea5f28..9ff2589497 100644
--- a/tests/test_server.py
+++ b/tests/test_server.py
@@ -392,8 +392,7 @@ class WrapHtmlRequestHandlerTests(unittest.TestCase):
         )
 
         self.assertEqual(channel.code, 301)
-        headers = channel.result["headers"]
-        location_headers = [v for k, v in headers if k == b"Location"]
+        location_headers = channel.headers.getRawHeaders(b"Location", [])
         self.assertEqual(location_headers, [b"/look/an/eagle"])
 
     def test_redirect_exception_with_cookie(self) -> None:
@@ -415,10 +414,10 @@ class WrapHtmlRequestHandlerTests(unittest.TestCase):
         )
 
         self.assertEqual(channel.code, 304)
-        headers = channel.result["headers"]
-        location_headers = [v for k, v in headers if k == b"Location"]
+        headers = channel.headers
+        location_headers = headers.getRawHeaders(b"Location", [])
         self.assertEqual(location_headers, [b"/no/over/there"])
-        cookies_headers = [v for k, v in headers if k == b"Set-Cookie"]
+        cookies_headers = headers.getRawHeaders(b"Set-Cookie", [])
         self.assertEqual(cookies_headers, [b"session=yespls"])
 
     def test_head_request(self) -> None: