Handle 1xx interim response codes (#605)

* Tests for 100 and 103 status codes

* Fix behaviour for 100 and 103 status codes

httpcore/_async/http11.py

@@ -153,7 +153,12 @@ async def _receive_response_headers(
 
         while True:
             event = await self._receive_event(timeout=timeout)
-            if isinstance(event, (h11.Response, h11.InformationalResponse)):
+            if isinstance(event, h11.Response):
+                break
+            if (
+                isinstance(event, h11.InformationalResponse)
+                and event.status_code == 101
+            ):
                 break
 
         http_version = b"HTTP/" + event.http_version

httpcore/_sync/http11.py

@@ -153,7 +153,12 @@ def _receive_response_headers(
 
         while True:
             event = self._receive_event(timeout=timeout)
-            if isinstance(event, (h11.Response, h11.InformationalResponse)):
+            if isinstance(event, h11.Response):
+                break
+            if (
+                isinstance(event, h11.InformationalResponse)
+                and event.status_code == 101
+            ):
                 break
 
         http_version = b"HTTP/" + event.http_version

tests/_async/test_http11.py

@@ -208,12 +208,54 @@ async def test_http11_request_to_incorrect_origin():
             await conn.request("GET", "https://other.com/")
 
 
+@pytest.mark.anyio
+async def test_http11_expect_continue():
+    """
+    HTTP "100 Continue" is an interim response.
+    We simply ignore it and return the final response.
+
+    https://httpwg.org/specs/rfc9110.html#status.100
+    https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/100
+    """
+    origin = Origin(b"https", b"example.com", 443)
+    stream = AsyncMockStream(
+        [
+            b"HTTP/1.1 100 Continue\r\n",
+            b"\r\n",
+            b"HTTP/1.1 200 OK\r\n",
+            b"Content-Type: plain/text\r\n",
+            b"Content-Length: 13\r\n",
+            b"\r\n",
+            b"Hello, world!",
+        ]
+    )
+    async with AsyncHTTP11Connection(
+        origin=origin, stream=stream, keepalive_expiry=5.0
+    ) as conn:
+        response = await conn.request(
+            "GET",
+            "https://example.com/",
+            headers={"Expect": "continue"},
+        )
+        assert response.status == 200
+        assert response.content == b"Hello, world!"
+
+
 @pytest.mark.anyio
 async def test_http11_upgrade_connection():
+    """
+    HTTP "101 Switching Protocols" indicates an upgraded connection.
+
+    We should return the response, so that the network stream
+    may be used for the upgraded connection.
+
+    https://httpwg.org/specs/rfc9110.html#status.101
+    https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/101
+    """
     origin = Origin(b"https", b"example.com", 443)
     stream = AsyncMockStream(
         [
-            b"HTTP/1.1 101 OK\r\n",
+            b"HTTP/1.1 101 Switching Protocols\r\n",
             b"Connection: upgrade\r\n",
             b"Upgrade: custom\r\n",
             b"\r\n",
@@ -232,3 +274,39 @@ async def test_http11_upgrade_connection():
             network_stream = response.extensions["network_stream"]
             content = await network_stream.read(max_bytes=1024)
             assert content == b"..."
+
+
+@pytest.mark.anyio
+async def test_http11_early_hints():
+    """
+    HTTP "103 Early Hints" is an interim response.
+    We simply ignore it and return the final response.
+
+    https://datatracker.ietf.org/doc/rfc8297/
+    """
+    origin = Origin(b"https", b"example.com", 443)
+    stream = AsyncMockStream(
+        [
+            b"HTTP/1.1 103 Early Hints\r\n",
+            b"Link: </style.css>; rel=preload; as=style\r\n",
+            b"Link: </script.js.css>; rel=preload; as=style\r\n",
+            b"\r\n",
+            b"HTTP/1.1 200 OK\r\n",
+            b"Content-Type: text/html; charset=utf-8\r\n",
+            b"Content-Length: 30\r\n",
+            b"Link: </style.css>; rel=preload; as=style\r\n",
+            b"Link: </script.js>; rel=preload; as=script\r\n",
+            b"\r\n",
+            b"<html>Hello, world! ...</html>",
+        ]
+    )
+    async with AsyncHTTP11Connection(
+        origin=origin, stream=stream, keepalive_expiry=5.0
+    ) as conn:
+        response = await conn.request(
+            "GET",
+            "https://example.com/",
+            headers={"Expect": "continue"},
+        )
+        assert response.status == 200
+        assert response.content == b"<html>Hello, world! ...</html>"

tests/_sync/test_http11.py

@@ -209,11 +209,53 @@ def test_http11_request_to_incorrect_origin():
 
 
 
+def test_http11_expect_continue():
+    """
+    HTTP "100 Continue" is an interim response.
+    We simply ignore it and return the final response.
+
+    https://httpwg.org/specs/rfc9110.html#status.100
+    https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/100
+    """
+    origin = Origin(b"https", b"example.com", 443)
+    stream = MockStream(
+        [
+            b"HTTP/1.1 100 Continue\r\n",
+            b"\r\n",
+            b"HTTP/1.1 200 OK\r\n",
+            b"Content-Type: plain/text\r\n",
+            b"Content-Length: 13\r\n",
+            b"\r\n",
+            b"Hello, world!",
+        ]
+    )
+    with HTTP11Connection(
+        origin=origin, stream=stream, keepalive_expiry=5.0
+    ) as conn:
+        response = conn.request(
+            "GET",
+            "https://example.com/",
+            headers={"Expect": "continue"},
+        )
+        assert response.status == 200
+        assert response.content == b"Hello, world!"
+
+
+
 def test_http11_upgrade_connection():
+    """
+    HTTP "101 Switching Protocols" indicates an upgraded connection.
+
+    We should return the response, so that the network stream
+    may be used for the upgraded connection.
+
+    https://httpwg.org/specs/rfc9110.html#status.101
+    https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/101
+    """
     origin = Origin(b"https", b"example.com", 443)
     stream = MockStream(
         [
-            b"HTTP/1.1 101 OK\r\n",
+            b"HTTP/1.1 101 Switching Protocols\r\n",
             b"Connection: upgrade\r\n",
             b"Upgrade: custom\r\n",
             b"\r\n",
@@ -232,3 +274,39 @@ def test_http11_upgrade_connection():
             network_stream = response.extensions["network_stream"]
             content = network_stream.read(max_bytes=1024)
             assert content == b"..."
+
+
+
+def test_http11_early_hints():
+    """
+    HTTP "103 Early Hints" is an interim response.
+    We simply ignore it and return the final response.
+
+    https://datatracker.ietf.org/doc/rfc8297/
+    """
+    origin = Origin(b"https", b"example.com", 443)
+    stream = MockStream(
+        [
+            b"HTTP/1.1 103 Early Hints\r\n",
+            b"Link: </style.css>; rel=preload; as=style\r\n",
+            b"Link: </script.js.css>; rel=preload; as=style\r\n",
+            b"\r\n",
+            b"HTTP/1.1 200 OK\r\n",
+            b"Content-Type: text/html; charset=utf-8\r\n",
+            b"Content-Length: 30\r\n",
+            b"Link: </style.css>; rel=preload; as=style\r\n",
+            b"Link: </script.js>; rel=preload; as=script\r\n",
+            b"\r\n",
+            b"<html>Hello, world! ...</html>",
+        ]
+    )
+    with HTTP11Connection(
+        origin=origin, stream=stream, keepalive_expiry=5.0
+    ) as conn:
+        response = conn.request(
+            "GET",
+            "https://example.com/",
+            headers={"Expect": "continue"},
+        )
+        assert response.status == 200
+        assert response.content == b"<html>Hello, world! ...</html>"