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import os
import httpx
import tempfile
import shutil
import brotli
from fastapi import Request
from fastapi.responses import StreamingResponse, FileResponse
from starlette.background import BackgroundTask
def _get_file_headers(local_path: str) -> dict:
headers = {
"Cross-Origin-Opener-Policy": "same-origin",
"Cross-Origin-Embedder-Policy": "require-corp"
}
if local_path.endswith(".br"):
headers["Content-Encoding"] = "br"
headers["Content-Type"] = "application/octet-stream"
return headers
def _get_media_type(local_path: str) -> str:
"""Get appropriate media type based on file extension."""
if local_path.endswith(".wasm.br") or local_path.endswith(".wasm"):
return "application/wasm"
if local_path.endswith(".br"):
return "application/octet-stream"
return None # Let FileResponse auto-detect
def get_local_file(local_path: str, request: Request = None) -> FileResponse | StreamingResponse | None:
"""
Get a local file as response. If it's a .br file and client doesn't accept brotli,
decompress it on the fly.
Args:
local_path: Path to the local file
request: Optional request object to check Accept-Encoding header
Returns:
FileResponse, StreamingResponse (for decompressed .br), or None if file not found
"""
if not os.path.isfile(local_path):
return None
headers = _get_file_headers(local_path)
media_type = _get_media_type(local_path)
# Check if we need to decompress .br file for client
is_br_file = local_path.endswith(".br")
need_decompress = is_br_file and request and not _client_accepts_brotli(request)
if need_decompress:
# Stream decompressed content
headers.pop("Content-Encoding", None)
headers["Content-Type"] = "application/octet-stream"
def iterate_decompressed():
with open(local_path, "rb") as f:
decompressor = brotli.Decompressor()
while chunk := f.read(65536): # 64KB chunks
yield decompressor.process(chunk)
return StreamingResponse(
iterate_decompressed(),
media_type="application/octet-stream",
headers=headers
)
if media_type:
return FileResponse(local_path, media_type=media_type, headers=headers)
return FileResponse(local_path, headers=headers)
def _client_accepts_brotli(request: Request) -> bool:
"""Check if client accepts brotli encoding."""
accept_encoding = request.headers.get("accept-encoding", "")
return "br" in accept_encoding.lower()
async def proxy_and_cache(request: Request, url: str, local_path: str = None, disable_cache: bool = False):
"""
Proxy request to upstream URL and optionally cache the response.
Args:
request: FastAPI request object
url: Upstream URL to proxy to
local_path: Local file path for caching (required if disable_cache is False)
disable_cache: If True, just proxy without caching or reading from local file
"""
if not disable_cache and local_path:
if response := get_local_file(local_path, request):
return response
# Check if this is a .br file and client doesn't support brotli
is_br_file = url.endswith(".br")
client_accepts_br = _client_accepts_brotli(request)
need_decompress = is_br_file and not client_accepts_br
client = httpx.AsyncClient(timeout=None)
headers = {k: v for k, v in request.headers.items() if k.lower() not in ["host", "content-length", "accept-encoding"]}
req = client.build_request(request.method, url, headers=headers)
r = await client.send(req, stream=True)
excluded_headers = {"transfer-encoding", "connection", "keep-alive", "upgrade", "content-security-policy"}
response_headers = {k: v for k, v in r.headers.items() if k.lower() not in excluded_headers}
response_headers["Cross-Origin-Opener-Policy"] = "same-origin"
response_headers["Cross-Origin-Embedder-Policy"] = "require-corp"
# If decompressing, remove content-encoding from response
if need_decompress:
response_headers.pop("content-encoding", None)
response_headers.pop("Content-Encoding", None)
# Also remove content-length since it will change after decompression
response_headers.pop("content-length", None)
response_headers.pop("Content-Length", None)
if r.status_code != 200 or disable_cache or not local_path:
async def stream_with_decompress():
decompressor = brotli.Decompressor() if need_decompress else None
try:
async for chunk in r.aiter_raw():
if decompressor:
yield decompressor.process(chunk)
else:
yield chunk
finally:
await r.aclose()
await client.aclose()
return StreamingResponse(
stream_with_decompress(),
status_code=r.status_code,
headers=response_headers
)
os.makedirs(os.path.dirname(local_path), exist_ok=True)
temp_file = tempfile.NamedTemporaryFile(delete=False, dir=os.path.dirname(local_path))
temp_file_path = temp_file.name
async def iterate_and_save():
success = False
decompressor = brotli.Decompressor() if need_decompress else None
try:
async for chunk in r.aiter_raw():
# Always save raw (compressed) data to cache
temp_file.write(chunk)
# Yield decompressed data if needed
if decompressor:
yield decompressor.process(chunk)
else:
yield chunk
temp_file.close()
# If we reached here, the stream was fully consumed
shutil.move(temp_file_path, local_path)
success = True
finally:
if not success:
temp_file.close()
if os.path.exists(temp_file_path):
os.remove(temp_file_path)
await r.aclose()
await client.aclose()
return StreamingResponse(
iterate_and_save(),
status_code=r.status_code,
headers=response_headers
)
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