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python-capport/src/capport/api/proxy_fix.py

83 lines
2.6 KiB
Python

from __future__ import annotations
import ipaddress
import typing
import quart
import werkzeug
from werkzeug.http import parse_list_header
from .app import app
def _get_first_in_list(value_list: str | None, allowed: typing.Sequence[str] = ()) -> str | None:
if not value_list:
return None
values = parse_list_header(value_list)
if values and values[0]:
if not allowed or values[0] in allowed:
return values[0]
return None
def local_proxy_fix(request: quart.Request):
if not request.remote_addr:
return
try:
addr = ipaddress.ip_address(request.remote_addr)
except ValueError:
# TODO: accept unix sockets somehow too?
return
if not addr.is_loopback:
return
client = _get_first_in_list(request.headers.get("X-Forwarded-For"))
if not client:
# assume this is always set behind reverse proxies supporting any of the headers
return
request.remote_addr = client
scheme = _get_first_in_list(request.headers.get("X-Forwarded-Proto"), ("http", "https"))
port: int | None = None
if scheme:
port = 443 if scheme == "https" else 80
request.scheme = scheme
host = _get_first_in_list(request.headers.get("X-Forwarded-Host"))
port_s: str | None
if host:
request.host = host
if ":" in host and not host.endswith("]"):
try:
_, port_s = host.rsplit(":", maxsplit=1)
port = int(port_s)
except ValueError:
# ignore invalid port in host header
pass
port_s = _get_first_in_list(request.headers.get("X-Forwarded-Port"))
if port_s:
try:
port = int(port_s)
except ValueError:
# ignore invalid port in header
pass
if port:
if request.server and len(request.server) == 2:
request.server = (request.server[0], port)
root_path = _get_first_in_list(request.headers.get("X-Forwarded-Prefix"))
if root_path:
request.root_path = root_path
class LocalProxyFixRequestHandler:
def __init__(
self,
orig_handle_request: typing.Callable[[quart.Request], typing.Awaitable[quart.Response | werkzeug.Response]],
):
self._orig_handle_request = orig_handle_request
async def __call__(self, request: quart.Request) -> quart.Response | werkzeug.Response:
# need to patch request before url_adapter is built
local_proxy_fix(request)
return await self._orig_handle_request(request)
app.handle_request = LocalProxyFixRequestHandler(app.handle_request) # type: ignore