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874 lines (739 loc) · 31.8 KB
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# --------------------------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# --------------------------------------------------------------------------------------------
"""CopilotRequestHandler: observe or replace outbound model-layer HTTP/WebSocket requests.
The SDK consumer subclasses :class:`CopilotRequestHandler` and overrides one or
both seams:
* HTTP — override :meth:`CopilotRequestHandler.send_request` to mutate the
:class:`httpx.Request`, post-process the :class:`httpx.Response`, or replace
the call entirely. The default forwards via a shared :class:`httpx.AsyncClient`.
* WebSocket — override :meth:`CopilotRequestHandler.open_websocket` to return
a per-connection :class:`CopilotWebSocketHandler`. The default opens a
transparent forwarding connection via the ``websockets`` library.
:func:`create_copilot_request_adapter` converts a handler into the generated
:class:`~copilot.generated.rpc.LlmInferenceHandler` shape so the RPC dispatcher
can route inbound ``httpRequestStart`` / ``httpRequestChunk`` frames through it.
"""
from __future__ import annotations
import asyncio
import base64
from collections.abc import AsyncIterator, Awaitable, Callable
from dataclasses import dataclass, field
from typing import TYPE_CHECKING, Any
from .generated.rpc import (
LlmInferenceHTTPRequestChunkRequest,
LlmInferenceHTTPRequestChunkResult,
LlmInferenceHTTPRequestStartRequest,
LlmInferenceHTTPRequestStartResult,
LlmInferenceHTTPResponseChunkError,
LlmInferenceHTTPResponseChunkRequest,
LlmInferenceHTTPResponseStartRequest,
ServerLlmInferenceApi,
)
if TYPE_CHECKING:
import httpx
# Multi-valued headers: header name → list of values.
LlmInferenceHeaders = dict[str, list[str]]
# Hop-by-hop and length headers the transport recomputes; forwarding them
# verbatim corrupts the request.
_FORBIDDEN_REQUEST_HEADERS = frozenset(
{
"host",
"connection",
"content-length",
"transfer-encoding",
"keep-alive",
"upgrade",
"proxy-connection",
"te",
"trailer",
}
)
_shared_http_client: httpx.AsyncClient | None = None
_HTTP_RESPONSE_READ_AHEAD_BYTES = 32 * 1024
def _get_shared_http_client() -> httpx.AsyncClient:
global _shared_http_client
if _shared_http_client is None:
import httpx
_shared_http_client = httpx.AsyncClient(timeout=None, follow_redirects=False)
return _shared_http_client
@dataclass
class CopilotRequestContext:
"""Per-request context handed to every :class:`CopilotRequestHandler` hook."""
request_id: str
"""Opaque runtime-minted id, stable across the request lifecycle."""
transport: str
"""``"http"`` (plain HTTP / SSE) or ``"websocket"`` (full-duplex channel)."""
url: str
"""Absolute request URL."""
headers: LlmInferenceHeaders
"""HTTP request headers, multi-valued."""
cancel_event: asyncio.Event
"""Set when the runtime cancels this in-flight request. Pass it through to
your transport so the upstream call is torn down too."""
session_id: str | None = None
"""Id of the runtime session that triggered this request, when in scope.
Absent for out-of-session requests (e.g. the startup model catalog)."""
agent_id: str | None = None
"""Stable per-agent-instance id for the agent trajectory that issued this request."""
parent_agent_id: str | None = None
"""Id of the parent agent when this request was issued by a subagent."""
interaction_type: str | None = None
"""Runtime classification for the interaction that produced this request."""
_bridge: _CopilotWebSocketResponseBridge | None = field(default=None, repr=False)
@dataclass
class CopilotWebSocketCloseStatus:
"""Terminal status for a callback-owned WebSocket connection."""
description: str | None = None
error_code: str | None = None
error: BaseException | None = None
@classmethod
def normal_closure(cls) -> CopilotWebSocketCloseStatus:
return cls()
class CopilotWebSocketHandler:
"""Per-connection WebSocket handler returned by
:meth:`CopilotRequestHandler.open_websocket`.
Subclass and override :meth:`send_request_message` (runtime → upstream) to
mutate, drop, or inject messages, and :meth:`send_response_message`
(upstream → runtime) for the reverse direction. A full transport replacement
overrides :meth:`open` to stand up its own connection and receive loop.
"""
def __init__(self, context: CopilotRequestContext) -> None:
bridge = context._bridge
if bridge is None:
raise RuntimeError("WebSocket response bridge is not attached")
self.context = context
self._response = bridge
self._completion: asyncio.Future[CopilotWebSocketCloseStatus] = (
asyncio.get_event_loop().create_future()
)
self._closed = False
self._suppress_close_on_dispose = False
async def send_response_message(self, data: str | bytes) -> None:
"""Forward an upstream message to the runtime response."""
await self._response.write(data)
async def send_request_message(self, data: str | bytes) -> None:
"""Forward a runtime message to the upstream connection. Override to mutate."""
raise NotImplementedError
async def close(self, status: CopilotWebSocketCloseStatus | None = None) -> None:
"""Initiate close: end the runtime response and resolve completion."""
if self._closed:
return
self._closed = True
status = status or CopilotWebSocketCloseStatus.normal_closure()
if status.error is not None:
await self._response.error(status.description or str(status.error), status.error_code)
else:
await self._response.end()
if not self._completion.done():
self._completion.set_result(status)
async def open(self) -> None:
"""Establish the connection. Default is a no-op for custom transports."""
async def aclose(self) -> None:
"""Final resource cleanup; closes normally if not already closed."""
if not self._suppress_close_on_dispose and not self._closed:
await self.close(CopilotWebSocketCloseStatus.normal_closure())
class CopilotWebSocketForwarder(CopilotWebSocketHandler):
"""Default pass-through WebSocket handler backed by the ``websockets`` library."""
def __init__(self, context: CopilotRequestContext) -> None:
super().__init__(context)
self._upstream: Any | None = None
self._receive_task: asyncio.Task[None] | None = None
async def send_request_message(self, data: str | bytes) -> None:
if self._upstream is None:
return
await self._upstream.send(data)
async def open(self) -> None:
if self._upstream is not None:
return
try:
import websockets
except ImportError as exc: # pragma: no cover - optional dependency
raise RuntimeError(
"WebSocket forwarding requires the 'websockets' package. "
"Install it or override open_websocket()."
) from exc
headers = [
(name, value)
for name, values in self.context.headers.items()
if name.lower() not in _FORBIDDEN_REQUEST_HEADERS
for value in (values or [])
]
self._upstream = await websockets.connect(self.context.url, additional_headers=headers)
self._receive_task = asyncio.create_task(self._receive_loop())
async def _receive_loop(self) -> None:
try:
async for message in self._upstream: # type: ignore[union-attr]
await self.send_response_message(message)
await self.close(CopilotWebSocketCloseStatus.normal_closure())
except asyncio.CancelledError:
raise
except Exception as exc:
await self.close(CopilotWebSocketCloseStatus(description=str(exc), error=exc))
async def close(self, status: CopilotWebSocketCloseStatus | None = None) -> None:
if self._upstream is not None:
try:
await self._upstream.close()
except Exception:
# Best-effort; the socket may already be closed.
pass
await super().close(status)
async def aclose(self) -> None:
try:
await super().aclose()
finally:
if self._receive_task is not None:
self._receive_task.cancel()
if self._upstream is not None:
try:
await self._upstream.close()
except Exception:
# Best-effort teardown: the upstream may already be closed.
pass
class CopilotRequestHandler:
"""Base class for consumers that observe or replace LLM inference requests.
Override :meth:`send_request` to intercept HTTP model-layer requests, or
:meth:`open_websocket` to intercept WebSocket connections. An instance
that overrides nothing is a transparent pass-through.
"""
async def send_request(
self, request: httpx.Request, ctx: CopilotRequestContext
) -> httpx.Response:
"""Send an HTTP request. Override to mutate request/response or replace the call."""
return await _get_shared_http_client().send(request, stream=True)
async def open_websocket(self, ctx: CopilotRequestContext) -> CopilotWebSocketHandler:
"""Open a per-connection WebSocket handler. Override to mutate or replace."""
return CopilotWebSocketForwarder(ctx)
async def _dispatch(self, exchange: _CopilotRequestExchange) -> None:
bridge = _CopilotWebSocketResponseBridge(exchange)
ctx = CopilotRequestContext(
request_id=exchange.request_id,
session_id=exchange.session_id,
agent_id=exchange.agent_id,
parent_agent_id=exchange.parent_agent_id,
interaction_type=exchange.interaction_type,
transport=exchange.transport,
url=exchange.url,
headers=exchange.headers,
cancel_event=exchange.cancel_event,
_bridge=bridge,
)
if exchange.transport == "websocket":
await self._handle_web_socket(exchange, ctx)
else:
await self._handle_http(exchange, ctx)
async def _handle_http(
self, exchange: _CopilotRequestExchange, ctx: CopilotRequestContext
) -> None:
request = await _build_httpx_request(exchange)
await _run_cancellable(self._forward_http(request, exchange, ctx), exchange.cancel_event)
async def _forward_http(
self,
request: httpx.Request,
exchange: _CopilotRequestExchange,
ctx: CopilotRequestContext,
) -> None:
response = await self.send_request(request, ctx)
try:
await _stream_response_to_exchange(response, exchange)
finally:
await response.aclose()
async def _handle_web_socket(
self, exchange: _CopilotRequestExchange, ctx: CopilotRequestContext
) -> None:
handler = await self.open_websocket(ctx)
assert ctx._bridge is not None
try:
await handler.open()
# Emit the 101 upgrade head eagerly. The runtime blocks the WS
# connect until it receives this acknowledgement, and only then
# starts forwarding inbound messages as request-body chunks.
# Waiting for the first upstream message would deadlock.
await ctx._bridge.start()
async def pump_client() -> str:
async for chunk in exchange.request_body:
await handler.send_request_message(_decode_frame(chunk))
return "client-complete"
client_task = asyncio.create_task(pump_client())
completion = asyncio.ensure_future(handler._completion)
done, _ = await asyncio.wait(
{client_task, completion}, return_when=asyncio.FIRST_COMPLETED
)
if client_task in done and client_task.exception() is not None:
handler._suppress_close_on_dispose = True
raise client_task.exception() # type: ignore[misc]
if client_task in done:
await handler.close(CopilotWebSocketCloseStatus.normal_closure())
await handler._completion
return
status = await handler._completion
if status.error is not None:
raise status.error
finally:
await handler.aclose()
# ---------------------------------------------------------------------------
# Internal exchange: request body feed + response emitter
# ---------------------------------------------------------------------------
@dataclass
class _BodyItem:
chunk: bytes | None = None
end: bool = False
cancel: bool = False
cancel_reason: str | None = None
class _BodyQueue:
"""An async iterator of request-body byte chunks fed by the runtime."""
def __init__(self) -> None:
self._queue: asyncio.Queue[_BodyItem] = asyncio.Queue()
self._done = False
def push(self, item: _BodyItem) -> None:
self._queue.put_nowait(item)
def __aiter__(self) -> AsyncIterator[bytes]:
return self
async def __anext__(self) -> bytes:
if self._done:
raise StopAsyncIteration
item = await self._queue.get()
if item.cancel:
self._done = True
reason = (
f"Request cancelled by runtime: {item.cancel_reason}"
if item.cancel_reason
else "Request cancelled by runtime"
)
raise RuntimeError(reason)
if item.end:
self._done = True
raise StopAsyncIteration
return item.chunk if item.chunk is not None else b""
class _CopilotRequestExchange:
"""One intercepted request in flight.
Carries the request body stream the runtime feeds via ``httpRequestChunk``
frames, and emits the handler's response directly to the runtime through
the generated ``llmInference`` RPC. Replaces the former provider / sink /
response-channel indirection with a single object the adapter owns.
"""
def __init__(
self,
request_id: str,
get_server_rpc: Callable[[], ServerLlmInferenceApi | None],
) -> None:
self.request_id = request_id
self.session_id: str | None = None
self.agent_id: str | None = None
self.parent_agent_id: str | None = None
self.interaction_type: str | None = None
self.method: str = "GET"
self.url: str = ""
self.headers: dict[str, list[str]] = {}
self.transport: str = "http"
self._get_server_rpc = get_server_rpc
self._queue = _BodyQueue()
self.cancel_event: asyncio.Event = asyncio.Event()
self.started: bool = False
self.finished: bool = False
self.cancelled: bool = False
self.task: asyncio.Task[None] | None = None
def set_context(self, params: LlmInferenceHTTPRequestStartRequest) -> None:
"""Fill in the request context once the matching start frame arrives."""
self.session_id = params.session_id
self.agent_id = params.agent_id
self.parent_agent_id = params.parent_agent_id
self.interaction_type = params.interaction_type
self.method = params.method
self.url = params.url
self.headers = params.headers
transport = params.transport
self.transport = transport.value if transport is not None else "http"
@property
def request_body(self) -> _BodyQueue:
return self._queue
def _require_rpc(self) -> ServerLlmInferenceApi:
rpc = self._get_server_rpc()
if rpc is None:
raise RuntimeError("Copilot request response used after RPC connection closed.")
return rpc
async def start_response(
self,
status: int,
status_text: str | None = None,
headers: LlmInferenceHeaders | None = None,
) -> None:
if self.started:
raise RuntimeError("Copilot request response start() called twice.")
if self.finished:
raise RuntimeError("Copilot request response already finished.")
self.started = True
await self._require_rpc().http_response_start(
LlmInferenceHTTPResponseStartRequest(
headers=headers or {},
request_id=self.request_id,
status=status,
status_text=status_text,
)
)
async def write_response(self, data: str | bytes) -> None:
if self.cancelled:
raise RuntimeError("Copilot request was cancelled by the runtime.")
if not self.started:
raise RuntimeError("Copilot request response write() called before start().")
if self.finished:
raise RuntimeError("Copilot request response write() called after end()/error().")
if isinstance(data, bytes):
payload = base64.b64encode(data).decode("ascii")
is_binary = True
else:
payload = data
is_binary = False
await self._require_rpc().http_response_chunk(
LlmInferenceHTTPResponseChunkRequest(
data=payload,
request_id=self.request_id,
binary=is_binary or None,
end=False,
)
)
async def end_response(self) -> None:
if self.finished:
return
self.finished = True
await self._require_rpc().http_response_chunk(
LlmInferenceHTTPResponseChunkRequest(data="", request_id=self.request_id, end=True)
)
async def error_response(self, message: str, code: str | None = None) -> None:
if self.finished:
return
self.finished = True
await self._require_rpc().http_response_chunk(
LlmInferenceHTTPResponseChunkRequest(
data="",
request_id=self.request_id,
end=True,
error=LlmInferenceHTTPResponseChunkError(message=message, code=code),
)
)
# ---------------------------------------------------------------------------
# Adapter: wires the handler into the generated RPC handler shape
# ---------------------------------------------------------------------------
def create_copilot_request_adapter(
handler: CopilotRequestHandler,
get_server_rpc: Callable[[], ServerLlmInferenceApi | None],
) -> _CopilotRequestAdapterHandler:
"""Adapt a :class:`CopilotRequestHandler` into the generated handler shape.
Maintains a per-``request_id`` table of :class:`_CopilotRequestExchange`:
each ``httpRequestStart`` allocates one and fires the handler in the
background, returning immediately so the runtime's RPC reply is not gated
on the consumer's I/O. Subsequent ``httpRequestChunk`` frames are routed
into the matching exchange's body stream.
"""
return _CopilotRequestAdapterHandler(handler, get_server_rpc)
class _CopilotRequestAdapterHandler:
def __init__(
self,
handler: CopilotRequestHandler,
get_server_rpc: Callable[[], ServerLlmInferenceApi | None],
) -> None:
self._handler = handler
self._get_server_rpc = get_server_rpc
self._pending: dict[str, _CopilotRequestExchange] = {}
def _route_chunk(
self,
exchange: _CopilotRequestExchange,
params: LlmInferenceHTTPRequestChunkRequest,
) -> None:
if params.cancel:
exchange.cancelled = True
exchange.cancel_event.set()
exchange._queue.push(_BodyItem(cancel=True, cancel_reason=params.cancel_reason))
return
if params.data:
exchange._queue.push(
_BodyItem(chunk=_decode_chunk_data(params.data, bool(params.binary)))
)
if params.end:
exchange._queue.push(_BodyItem(end=True))
async def _run(self, exchange: _CopilotRequestExchange) -> None:
try:
await self._handler._dispatch(exchange)
if not exchange.finished:
await _finalize(
exchange,
502,
"Copilot request handler returned without finalising the response.",
)
except Exception as exc:
if exchange.cancelled or exchange.cancel_event.is_set():
await _finalize(exchange, 499, "Request cancelled by runtime", "cancelled")
return
await _finalize(exchange, 502, str(exc))
finally:
self._pending.pop(exchange.request_id, None)
def cancel_pending(self) -> None:
exchanges = tuple(self._pending.values())
self._pending.clear()
for exchange in exchanges:
exchange.cancelled = True
exchange.cancel_event.set()
exchange._queue.push(_BodyItem(cancel=True, cancel_reason="RPC connection closed"))
def _get_or_create(self, request_id: str) -> _CopilotRequestExchange:
# The runtime dispatches httpRequestStart and httpRequestChunk frames
# independently. get-or-create keeps the adapter correct regardless of
# arrival order: a body chunk (including the terminal end frame) that
# races ahead of its start frame is buffered into the same exchange
# rather than dropped, which would otherwise hang the body drain.
exchange = self._pending.get(request_id)
if exchange is None:
exchange = _CopilotRequestExchange(request_id, self._get_server_rpc)
self._pending[request_id] = exchange
return exchange
async def http_request_start(
self, params: LlmInferenceHTTPRequestStartRequest
) -> LlmInferenceHTTPRequestStartResult:
# Adopt any exchange a racing chunk already created — with its buffered
# body — rather than dropping those frames.
exchange = self._get_or_create(params.request_id)
exchange.set_context(params)
exchange.task = asyncio.create_task(self._run(exchange))
return LlmInferenceHTTPRequestStartResult()
async def http_request_chunk(
self, params: LlmInferenceHTTPRequestChunkRequest
) -> LlmInferenceHTTPRequestChunkResult:
# May arrive before the matching start frame; get-or-create so the body
# is buffered, never lost.
exchange = self._get_or_create(params.request_id)
self._route_chunk(exchange, params)
return LlmInferenceHTTPRequestChunkResult()
async def _finalize(
exchange: _CopilotRequestExchange,
status: int,
message: str,
code: str | None = None,
) -> None:
if exchange.finished:
return
try:
if not exchange.started:
await exchange.start_response(status)
await exchange.error_response(message, code)
except Exception:
# Best-effort — the connection may already be dead.
pass
# ---------------------------------------------------------------------------
# WebSocket response bridge
# ---------------------------------------------------------------------------
class _CopilotWebSocketResponseBridge:
"""Serialises WebSocket response writes into the exchange.
The 101 upgrade head is emitted eagerly via :meth:`start` (the runtime
gates the WS connect on it); subsequent writes and the terminal frame are
serialised via a lock so the head always precedes them. The lazy-start
path in :meth:`write` acts as a no-op backstop when ``start`` is called
first (the normal case).
"""
def __init__(self, exchange: _CopilotRequestExchange) -> None:
self._exchange = exchange
self._started = False
self._completed = False
self._lock = asyncio.Lock()
async def start(self) -> None:
"""Emit the 101 upgrade acknowledgement now."""
async with self._lock:
if self._started:
return
self._started = True
await self._exchange.start_response(101, headers={})
async def write(self, data: str | bytes) -> None:
async with self._lock:
if not self._started:
# Lazy-start backstop: emits the 101 head if a subclass calls
# write before start(). In normal usage start() is called
# eagerly in _handle_web_socket so this branch is never taken.
self._started = True
await self._exchange.start_response(101, headers={})
if not self._completed:
await self._exchange.write_response(data)
async def end(self) -> None:
async with self._lock:
if self._completed:
return
self._completed = True
await self._exchange.end_response()
async def error(self, message: str, code: str | None = None) -> None:
async with self._lock:
if self._completed:
return
self._completed = True
await self._exchange.error_response(message, code)
# ---------------------------------------------------------------------------
# HTTP helpers
# ---------------------------------------------------------------------------
async def _run_cancellable(coro: Any, cancel_event: asyncio.Event) -> None:
"""Run ``coro`` but abort it (and raise) when ``cancel_event`` fires."""
task = asyncio.ensure_future(coro)
waiter = asyncio.ensure_future(cancel_event.wait())
try:
done, _ = await asyncio.wait({task, waiter}, return_when=asyncio.FIRST_COMPLETED)
if task in done:
exc = task.exception()
if exc is not None:
raise exc
return
# Cancellation fired first.
task.cancel()
try:
await task
except (asyncio.CancelledError, Exception):
# The awaited task was cancelled; its unwind exception is expected
# and irrelevant — we raise the cancellation result below.
pass
raise RuntimeError("Request cancelled by runtime")
finally:
if not waiter.done():
waiter.cancel()
async def _build_httpx_request(exchange: _CopilotRequestExchange) -> httpx.Request:
import httpx
header_pairs = [
(name, value)
for name, values in exchange.headers.items()
if name.lower() not in _FORBIDDEN_REQUEST_HEADERS
for value in (values or [])
]
method = exchange.method.upper()
has_body = method not in ("GET", "HEAD")
body = await _drain_async(exchange.request_body)
content = body if (has_body and body) else None
return httpx.Request(method, exchange.url, headers=header_pairs, content=content)
async def _drain_async(stream: AsyncIterator[bytes]) -> bytes:
parts: list[bytes] = []
async for chunk in stream:
if chunk:
parts.append(chunk)
return b"".join(parts)
async def _stream_response_to_exchange(
response: httpx.Response, exchange: _CopilotRequestExchange
) -> None:
await exchange.start_response(
response.status_code,
status_text=response.reason_phrase or None,
headers=_headers_to_multi_map(response.headers),
)
if response.is_stream_consumed:
# An in-memory response (built with ``content=``) has already buffered its
# body, so its raw stream cannot be iterated.
async def body_stream() -> AsyncIterator[bytes]:
if response.content:
yield response.content
source = body_stream()
else:
source = response.aiter_raw()
reader = _HttpResponseReader(source, response.aclose)
try:
while True:
chunk = await reader.next_chunk()
if chunk is None:
await exchange.end_response()
return
await exchange.write_response(chunk)
finally:
await reader.aclose()
class _HttpResponseReader:
"""Bounded response-body read-ahead with immediate partial flushes."""
def __init__(
self,
source: AsyncIterator[bytes],
close_response: Callable[[], Awaitable[None]],
) -> None:
self._source = source.__aiter__()
self._close_response = close_response
self._frames: list[bytes] = []
self._queued = 0
self._error: Exception | None = None
self._done = False
self._closed = False
self._condition = asyncio.Condition()
self._producer = asyncio.create_task(self._produce())
async def _produce(self) -> None:
try:
while True:
async with self._condition:
await self._condition.wait_for(
lambda: self._closed or self._queued < _HTTP_RESPONSE_READ_AHEAD_BYTES
)
if self._closed:
return
# Always-ready custom iterators must yield so an awaiting
# consumer can flush the first available frame immediately.
await asyncio.sleep(0)
frame = await anext(self._source)
if not frame:
continue
async with self._condition:
if self._closed:
return
self._frames.append(frame)
self._queued += len(frame)
self._condition.notify_all()
except StopAsyncIteration:
# Normal source exhaustion.
pass
except asyncio.CancelledError:
raise
except Exception as exc:
async with self._condition:
if not self._closed:
self._error = exc
finally:
close_error: Exception | None = None
close = getattr(self._source, "aclose", None)
if close is not None:
try:
await close()
except Exception as exc:
close_error = exc
try:
await self._close_response()
except Exception as exc:
close_error = close_error or exc
async with self._condition:
if not self._closed and self._error is None:
self._error = close_error
self._done = True
self._condition.notify_all()
async def next_chunk(self) -> bytes | None:
async with self._condition:
await self._condition.wait_for(
lambda: self._frames or self._error is not None or self._done
)
if self._frames:
# A lone frame is forwarded as-is; joining is only needed once
# read-ahead has run past the chunk awaiting acknowledgement.
chunk = self._frames[0] if len(self._frames) == 1 else b"".join(self._frames)
self._frames.clear()
self._queued = 0
self._condition.notify_all()
return chunk
if self._error is not None:
error = self._error
self._error = None
raise error
return None
async def aclose(self) -> None:
async with self._condition:
self._closed = True
self._condition.notify_all()
if not self._producer.done():
self._producer.cancel()
try:
await self._producer
except asyncio.CancelledError:
# Producer cancellation is expected during teardown.
pass
def _headers_to_multi_map(headers: Any) -> LlmInferenceHeaders:
out: dict[str, list[str]] = {}
for name, value in headers.multi_items():
out.setdefault(name, []).append(value)
return out
def _decode_chunk_data(data: str, binary: bool) -> bytes:
if binary:
return base64.b64decode(data)
return data.encode("utf-8")
def _decode_frame(chunk: bytes) -> str:
return chunk.decode("utf-8", errors="replace")
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