1 files changed, 172 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/starlette/middleware/cors.py b/.venv/lib/python3.12/site-packages/starlette/middleware/cors.py
new file mode 100644
index 00000000..61502691
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/starlette/middleware/cors.py
@@ -0,0 +1,172 @@
+from __future__ import annotations
+
+import functools
+import re
+import typing
+
+from starlette.datastructures import Headers, MutableHeaders
+from starlette.responses import PlainTextResponse, Response
+from starlette.types import ASGIApp, Message, Receive, Scope, Send
+
+ALL_METHODS = ("DELETE", "GET", "HEAD", "OPTIONS", "PATCH", "POST", "PUT")
+SAFELISTED_HEADERS = {"Accept", "Accept-Language", "Content-Language", "Content-Type"}
+
+
+class CORSMiddleware:
+    def __init__(
+        self,
+        app: ASGIApp,
+        allow_origins: typing.Sequence[str] = (),
+        allow_methods: typing.Sequence[str] = ("GET",),
+        allow_headers: typing.Sequence[str] = (),
+        allow_credentials: bool = False,
+        allow_origin_regex: str | None = None,
+        expose_headers: typing.Sequence[str] = (),
+        max_age: int = 600,
+    ) -> None:
+        if "*" in allow_methods:
+            allow_methods = ALL_METHODS
+
+        compiled_allow_origin_regex = None
+        if allow_origin_regex is not None:
+            compiled_allow_origin_regex = re.compile(allow_origin_regex)
+
+        allow_all_origins = "*" in allow_origins
+        allow_all_headers = "*" in allow_headers
+        preflight_explicit_allow_origin = not allow_all_origins or allow_credentials
+
+        simple_headers = {}
+        if allow_all_origins:
+            simple_headers["Access-Control-Allow-Origin"] = "*"
+        if allow_credentials:
+            simple_headers["Access-Control-Allow-Credentials"] = "true"
+        if expose_headers:
+            simple_headers["Access-Control-Expose-Headers"] = ", ".join(expose_headers)
+
+        preflight_headers = {}
+        if preflight_explicit_allow_origin:
+            # The origin value will be set in preflight_response() if it is allowed.
+            preflight_headers["Vary"] = "Origin"
+        else:
+            preflight_headers["Access-Control-Allow-Origin"] = "*"
+        preflight_headers.update(
+            {
+                "Access-Control-Allow-Methods": ", ".join(allow_methods),
+                "Access-Control-Max-Age": str(max_age),
+            }
+        )
+        allow_headers = sorted(SAFELISTED_HEADERS | set(allow_headers))
+        if allow_headers and not allow_all_headers:
+            preflight_headers["Access-Control-Allow-Headers"] = ", ".join(allow_headers)
+        if allow_credentials:
+            preflight_headers["Access-Control-Allow-Credentials"] = "true"
+
+        self.app = app
+        self.allow_origins = allow_origins
+        self.allow_methods = allow_methods
+        self.allow_headers = [h.lower() for h in allow_headers]
+        self.allow_all_origins = allow_all_origins
+        self.allow_all_headers = allow_all_headers
+        self.preflight_explicit_allow_origin = preflight_explicit_allow_origin
+        self.allow_origin_regex = compiled_allow_origin_regex
+        self.simple_headers = simple_headers
+        self.preflight_headers = preflight_headers
+
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
+        if scope["type"] != "http":  # pragma: no cover
+            await self.app(scope, receive, send)
+            return
+
+        method = scope["method"]
+        headers = Headers(scope=scope)
+        origin = headers.get("origin")
+
+        if origin is None:
+            await self.app(scope, receive, send)
+            return
+
+        if method == "OPTIONS" and "access-control-request-method" in headers:
+            response = self.preflight_response(request_headers=headers)
+            await response(scope, receive, send)
+            return
+
+        await self.simple_response(scope, receive, send, request_headers=headers)
+
+    def is_allowed_origin(self, origin: str) -> bool:
+        if self.allow_all_origins:
+            return True
+
+        if self.allow_origin_regex is not None and self.allow_origin_regex.fullmatch(origin):
+            return True
+
+        return origin in self.allow_origins
+
+    def preflight_response(self, request_headers: Headers) -> Response:
+        requested_origin = request_headers["origin"]
+        requested_method = request_headers["access-control-request-method"]
+        requested_headers = request_headers.get("access-control-request-headers")
+
+        headers = dict(self.preflight_headers)
+        failures = []
+
+        if self.is_allowed_origin(origin=requested_origin):
+            if self.preflight_explicit_allow_origin:
+                # The "else" case is already accounted for in self.preflight_headers
+                # and the value would be "*".
+                headers["Access-Control-Allow-Origin"] = requested_origin
+        else:
+            failures.append("origin")
+
+        if requested_method not in self.allow_methods:
+            failures.append("method")
+
+        # If we allow all headers, then we have to mirror back any requested
+        # headers in the response.
+        if self.allow_all_headers and requested_headers is not None:
+            headers["Access-Control-Allow-Headers"] = requested_headers
+        elif requested_headers is not None:
+            for header in [h.lower() for h in requested_headers.split(",")]:
+                if header.strip() not in self.allow_headers:
+                    failures.append("headers")
+                    break
+
+        # We don't strictly need to use 400 responses here, since its up to
+        # the browser to enforce the CORS policy, but its more informative
+        # if we do.
+        if failures:
+            failure_text = "Disallowed CORS " + ", ".join(failures)
+            return PlainTextResponse(failure_text, status_code=400, headers=headers)
+
+        return PlainTextResponse("OK", status_code=200, headers=headers)
+
+    async def simple_response(self, scope: Scope, receive: Receive, send: Send, request_headers: Headers) -> None:
+        send = functools.partial(self.send, send=send, request_headers=request_headers)
+        await self.app(scope, receive, send)
+
+    async def send(self, message: Message, send: Send, request_headers: Headers) -> None:
+        if message["type"] != "http.response.start":
+            await send(message)
+            return
+
+        message.setdefault("headers", [])
+        headers = MutableHeaders(scope=message)
+        headers.update(self.simple_headers)
+        origin = request_headers["Origin"]
+        has_cookie = "cookie" in request_headers
+
+        # If request includes any cookie headers, then we must respond
+        # with the specific origin instead of '*'.
+        if self.allow_all_origins and has_cookie:
+            self.allow_explicit_origin(headers, origin)
+
+        # If we only allow specific origins, then we have to mirror back
+        # the Origin header in the response.
+        elif not self.allow_all_origins and self.is_allowed_origin(origin=origin):
+            self.allow_explicit_origin(headers, origin)
+
+        await send(message)
+
+    @staticmethod
+    def allow_explicit_origin(headers: MutableHeaders, origin: str) -> None:
+        headers["Access-Control-Allow-Origin"] = origin
+        headers.add_vary_header("Origin")