Method __call__

python/vercel-runtime/src/vercel_runtime/vc_init.py:545–699

(
        self,
        scope: _ASGIScope,
        receive: _ASGIReceive,
        send: _ASGISend,
    )

        self.app = app

    async def __call__(
        self,
        scope: _ASGIScope,
        receive: _ASGIReceive,
        send: _ASGISend,
    ) -> None:
        scope_type = scope.get("type")
        if scope_type not in ("http", "websocket"):
            # Non-HTTP/WebSocket traffic is forwarded verbatim
            await self.app(scope, receive, send)
            return

        if scope_type == "http" and scope.get("path") == "/_vercel/ping":
            await send(
                {
                    "type": "http.response.start",
                    "status": 200,
                    "headers": [],
                }
            )
            await send(
                {
                    "type": "http.response.body",
                    "body": b"",
                    "more_body": False,
                }
            )
            return

        # Extract internal headers and set per-request context
        headers_list: list[tuple[bytes | str, bytes | str]] = (
            scope.get("headers", []) or []
        )
        new_headers: list[tuple[bytes, bytes]] = []
        invocation_id = "0"
        request_id = 0
        internal_oidc_token: str | None = None
        sc_pairs: list[tuple[bytes, bytes]] = []
        sc_no_header_leak = False

        for raw_k, raw_v in headers_list:
            key_bytes = raw_k if isinstance(raw_k, bytes) else raw_k.encode()
            val_bytes = raw_v if isinstance(raw_v, bytes) else raw_v.encode()
            key = decode_header_bytes(key_bytes).lower()
            val = decode_header_bytes(val_bytes)
            if key == "x-vercel-internal-invocation-id":
                invocation_id = val
                continue
            if key == "x-vercel-internal-request-id":
                request_id = int(val) if val.isdigit() else 0
                continue
            if key in (
                "x-vercel-internal-span-id",
                "x-vercel-internal-trace-id",
            ):
                continue
            if key == INTERNAL_OIDC_HEADER_NAME:
                internal_oidc_token = val