Add HTTP3 support

httpcore/__init__.py

@@ -3,6 +3,7 @@
     AsyncConnectionInterface,
     AsyncConnectionPool,
     AsyncHTTP2Connection,
+    AsyncHTTP3Connection,
     AsyncHTTP11Connection,
     AsyncHTTPConnection,
     AsyncHTTPProxy,
@@ -40,6 +41,7 @@
     ConnectionInterface,
     ConnectionPool,
     HTTP2Connection,
+    HTTP3Connection,
     HTTP11Connection,
     HTTPConnection,
     HTTPProxy,
@@ -85,6 +87,7 @@ def __init__(self, *args, **kwargs):  # type: ignore
     "AsyncHTTPProxy",
     "AsyncHTTP11Connection",
     "AsyncHTTP2Connection",
+    "AsyncHTTP3Connection",
     "AsyncConnectionInterface",
     "AsyncSOCKSProxy",
     # sync
@@ -93,6 +96,7 @@ def __init__(self, *args, **kwargs):  # type: ignore
     "HTTPProxy",
     "HTTP11Connection",
     "HTTP2Connection",
+    "HTTP3Connection",
     "ConnectionInterface",
     "SOCKSProxy",
     # network backends, implementations

httpcore/_async/__init__.py

@@ -16,6 +16,18 @@ def __init__(self, *args, **kwargs) -> None:  # type: ignore
             )
 
 
+try:
+    from .http3 import AsyncHTTP3Connection
+except ImportError:  # pragma: nocover
+
+    class AsyncHTTP3Connection:  # type: ignore
+        def __init__(self, *args, **kwargs) -> None:  # type: ignore
+            raise RuntimeError(
+                "Attempted to use http3 support, but the `aioquic` package is not "
+                "installed. Use 'pip install httpcore[http3]'."
+            )
+
+
 try:
     from .socks_proxy import AsyncSOCKSProxy
 except ImportError:  # pragma: nocover
@@ -34,6 +46,7 @@ def __init__(self, *args, **kwargs) -> None:  # type: ignore
     "AsyncHTTPProxy",
     "AsyncHTTP11Connection",
     "AsyncHTTP2Connection",
+    "AsyncHTTP3Connection",
     "AsyncConnectionInterface",
     "AsyncSOCKSProxy",
 ]

httpcore/_async/connection.py

@@ -41,6 +41,7 @@ def __init__(
         keepalive_expiry: Optional[float] = None,
         http1: bool = True,
         http2: bool = False,
+        http3: bool = False,
         retries: int = 0,
         local_address: Optional[str] = None,
         uds: Optional[str] = None,
@@ -52,6 +53,7 @@ def __init__(
         self._keepalive_expiry = keepalive_expiry
         self._http1 = http1
         self._http2 = http2
+        self._http3 = http3
         self._retries = retries
         self._local_address = local_address
         self._uds = uds
@@ -80,7 +82,18 @@ async def handle_async_request(self, request: Request) -> Response:
                         ssl_object is not None
                         and ssl_object.selected_alpn_protocol() == "h2"
                     )
-                    if http2_negotiated or (self._http2 and not self._http1):
+                    if self._http3 and not (
+                        self._http1 or self._http2
+                    ):  # pragma: no cover
+                        from .http3 import AsyncHTTP3Connection
+
+                        stream = await self._connect_http3(request)
+                        self._connection = AsyncHTTP3Connection(
+                            origin=self._origin,
+                            stream=stream,
+                            keepalive_expiry=self._keepalive_expiry,
+                        )
+                    elif http2_negotiated or (self._http2 and not self._http1):
                         from .http2 import AsyncHTTP2Connection
 
                         self._connection = AsyncHTTP2Connection(
@@ -162,6 +175,30 @@ async def _connect(self, request: Request) -> AsyncNetworkStream:
                 async with Trace("retry", logger, request, kwargs) as trace:
                     await self._network_backend.sleep(delay)
 
+    async def _connect_http3(
+        self, request: Request
+    ) -> AsyncNetworkStream:  # pragma: nocover
+        retries_left = self._retries
+        delays = exponential_backoff(factor=RETRIES_BACKOFF_FACTOR)
+
+        while True:
+            try:
+                kwargs = {
+                    "host": self._origin.host.decode("ascii"),
+                    "port": self._origin.port,
+                }
+                async with Trace("connect_udp", logger, request, kwargs) as trace:
+                    stream = await self._network_backend.connect_udp(**kwargs)  # type: ignore
+                    trace.return_value = stream
+                return stream
+            except (ConnectError, ConnectTimeout):
+                if retries_left <= 0:
+                    raise
+                retries_left -= 1
+                delay = next(delays)
+                async with Trace("retry", logger, request, kwargs) as trace:
+                    await self._network_backend.sleep(delay)
+
     def can_handle_request(self, origin: Origin) -> bool:
         return origin == self._origin
 

httpcore/_async/connection_pool.py

@@ -53,6 +53,7 @@ def __init__(
         keepalive_expiry: Optional[float] = None,
         http1: bool = True,
         http2: bool = False,
+        http3: bool = False,
         retries: int = 0,
         local_address: Optional[str] = None,
         uds: Optional[str] = None,
@@ -77,6 +78,8 @@ def __init__(
                 by the connection pool. Defaults to True.
             http2: A boolean indicating if HTTP/2 requests should be supported by
                 the connection pool. Defaults to False.
+            http3: A boolean indicating if HTTP/3 requests should be supported by
+                the connection pool. Defaults to False.
             retries: The maximum number of retries when trying to establish a
                 connection.
             local_address: Local address to connect from. Can also be used to connect
@@ -105,6 +108,7 @@ def __init__(
         self._keepalive_expiry = keepalive_expiry
         self._http1 = http1
         self._http2 = http2
+        self._http3 = http3
         self._retries = retries
         self._local_address = local_address
         self._uds = uds
@@ -131,6 +135,7 @@ def create_connection(self, origin: Origin) -> AsyncConnectionInterface:
             keepalive_expiry=self._keepalive_expiry,
             http1=self._http1,
             http2=self._http2,
+            http3=self._http3,
             retries=self._retries,
             local_address=self._local_address,
             uds=self._uds,