--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/urllib3/http2.py	Sun May 05 23:32:17 2024 -0400
@@ -0,0 +1,229 @@
+from __future__ import annotations
+
+import threading
+import types
+import typing
+
+import h2.config  # type: ignore[import-untyped]
+import h2.connection  # type: ignore[import-untyped]
+import h2.events  # type: ignore[import-untyped]
+
+import urllib3.connection
+import urllib3.util.ssl_
+from urllib3.response import BaseHTTPResponse
+
+from ._collections import HTTPHeaderDict
+from .connection import HTTPSConnection
+from .connectionpool import HTTPSConnectionPool
+
+orig_HTTPSConnection = HTTPSConnection
+
+T = typing.TypeVar("T")
+
+
+class _LockedObject(typing.Generic[T]):
+    """
+    A wrapper class that hides a specific object behind a lock.
+
+    The goal here is to provide a simple way to protect access to an object
+    that cannot safely be simultaneously accessed from multiple threads. The
+    intended use of this class is simple: take hold of it with a context
+    manager, which returns the protected object.
+    """
+
+    def __init__(self, obj: T):
+        self.lock = threading.RLock()
+        self._obj = obj
+
+    def __enter__(self) -> T:
+        self.lock.acquire()
+        return self._obj
+
+    def __exit__(
+        self,
+        exc_type: type[BaseException] | None,
+        exc_val: BaseException | None,
+        exc_tb: types.TracebackType | None,
+    ) -> None:
+        self.lock.release()
+
+
+class HTTP2Connection(HTTPSConnection):
+    def __init__(
+        self, host: str, port: int | None = None, **kwargs: typing.Any
+    ) -> None:
+        self._h2_conn = self._new_h2_conn()
+        self._h2_stream: int | None = None
+        self._h2_headers: list[tuple[bytes, bytes]] = []
+
+        if "proxy" in kwargs or "proxy_config" in kwargs:  # Defensive:
+            raise NotImplementedError("Proxies aren't supported with HTTP/2")
+
+        super().__init__(host, port, **kwargs)
+
+    def _new_h2_conn(self) -> _LockedObject[h2.connection.H2Connection]:
+        config = h2.config.H2Configuration(client_side=True)
+        return _LockedObject(h2.connection.H2Connection(config=config))
+
+    def connect(self) -> None:
+        super().connect()
+
+        with self._h2_conn as h2_conn:
+            h2_conn.initiate_connection()
+            self.sock.sendall(h2_conn.data_to_send())
+
+    def putrequest(
+        self,
+        method: str,
+        url: str,
+        skip_host: bool = False,
+        skip_accept_encoding: bool = False,
+    ) -> None:
+        with self._h2_conn as h2_conn:
+            self._request_url = url
+            self._h2_stream = h2_conn.get_next_available_stream_id()
+
+            if ":" in self.host:
+                authority = f"[{self.host}]:{self.port or 443}"
+            else:
+                authority = f"{self.host}:{self.port or 443}"
+
+            self._h2_headers.extend(
+                (
+                    (b":scheme", b"https"),
+                    (b":method", method.encode()),
+                    (b":authority", authority.encode()),
+                    (b":path", url.encode()),
+                )
+            )
+
+    def putheader(self, header: str, *values: str) -> None:  # type: ignore[override]
+        for value in values:
+            self._h2_headers.append(
+                (header.encode("utf-8").lower(), value.encode("utf-8"))
+            )
+
+    def endheaders(self) -> None:  # type: ignore[override]
+        with self._h2_conn as h2_conn:
+            h2_conn.send_headers(
+                stream_id=self._h2_stream,
+                headers=self._h2_headers,
+                end_stream=True,
+            )
+            if data_to_send := h2_conn.data_to_send():
+                self.sock.sendall(data_to_send)
+
+    def send(self, data: bytes) -> None:  # type: ignore[override]  # Defensive:
+        if not data:
+            return
+        raise NotImplementedError("Sending data isn't supported yet")
+
+    def getresponse(  # type: ignore[override]
+        self,
+    ) -> HTTP2Response:
+        status = None
+        data = bytearray()
+        with self._h2_conn as h2_conn:
+            end_stream = False
+            while not end_stream:
+                # TODO: Arbitrary read value.
+                if received_data := self.sock.recv(65535):
+                    events = h2_conn.receive_data(received_data)
+                    for event in events:
+                        if isinstance(event, h2.events.ResponseReceived):
+                            headers = HTTPHeaderDict()
+                            for header, value in event.headers:
+                                if header == b":status":
+                                    status = int(value.decode())
+                                else:
+                                    headers.add(
+                                        header.decode("ascii"), value.decode("ascii")
+                                    )
+
+                        elif isinstance(event, h2.events.DataReceived):
+                            data += event.data
+                            h2_conn.acknowledge_received_data(
+                                event.flow_controlled_length, event.stream_id
+                            )
+
+                        elif isinstance(event, h2.events.StreamEnded):
+                            end_stream = True
+
+                if data_to_send := h2_conn.data_to_send():
+                    self.sock.sendall(data_to_send)
+
+        # We always close to not have to handle connection management.
+        self.close()
+
+        assert status is not None
+        return HTTP2Response(
+            status=status,
+            headers=headers,
+            request_url=self._request_url,
+            data=bytes(data),
+        )
+
+    def close(self) -> None:
+        with self._h2_conn as h2_conn:
+            try:
+                h2_conn.close_connection()
+                if data := h2_conn.data_to_send():
+                    self.sock.sendall(data)
+            except Exception:
+                pass
+
+        # Reset all our HTTP/2 connection state.
+        self._h2_conn = self._new_h2_conn()
+        self._h2_stream = None
+        self._h2_headers = []
+
+        super().close()
+
+
+class HTTP2Response(BaseHTTPResponse):
+    # TODO: This is a woefully incomplete response object, but works for non-streaming.
+    def __init__(
+        self,
+        status: int,
+        headers: HTTPHeaderDict,
+        request_url: str,
+        data: bytes,
+        decode_content: bool = False,  # TODO: support decoding
+    ) -> None:
+        super().__init__(
+            status=status,
+            headers=headers,
+            # Following CPython, we map HTTP versions to major * 10 + minor integers
+            version=20,
+            # No reason phrase in HTTP/2
+            reason=None,
+            decode_content=decode_content,
+            request_url=request_url,
+        )
+        self._data = data
+        self.length_remaining = 0
+
+    @property
+    def data(self) -> bytes:
+        return self._data
+
+    def get_redirect_location(self) -> None:
+        return None
+
+    def close(self) -> None:
+        pass
+
+
+def inject_into_urllib3() -> None:
+    HTTPSConnectionPool.ConnectionCls = HTTP2Connection
+    urllib3.connection.HTTPSConnection = HTTP2Connection  # type: ignore[misc]
+
+    # TODO: Offer 'http/1.1' as well, but for testing purposes this is handy.
+    urllib3.util.ssl_.ALPN_PROTOCOLS = ["h2"]
+
+
+def extract_from_urllib3() -> None:
+    HTTPSConnectionPool.ConnectionCls = orig_HTTPSConnection
+    urllib3.connection.HTTPSConnection = orig_HTTPSConnection  # type: ignore[misc]
+
+    urllib3.util.ssl_.ALPN_PROTOCOLS = ["http/1.1"]