Class FlowReader

mitmproxy/io/io.py:27–81

class FlowReader:
    fo: BinaryIO

    def __init__(self, fo: BinaryIO):
        self.fo = fo

    def peek(self, n: int) -> bytes:
        try:
            return cast(BufferedReader, self.fo).peek(n)
        except AttributeError:
            # https://github.com/python/cpython/issues/90533: io.BytesIO does not have peek()
            pos = self.fo.tell()
            ret = self.fo.read(n)
            self.fo.seek(pos)
            return ret

    def stream(self) -> Iterable[flow.Flow]:
        """
        Yields Flow objects from the dump.
        """

        if self.peek(4).startswith(
            b"\xef\xbb\xbf{"
        ):  # skip BOM, usually added by Fiddler
            self.fo.read(3)
        if self.peek(1).startswith(b"{"):
            try:
                har_file = json.loads(self.fo.read().decode("utf-8"))

                for request_json in har_file["log"]["entries"]:
                    yield request_to_flow(request_json)

            except Exception:
                raise exceptions.FlowReadException(
                    "Unable to read HAR file. Please provide a valid HAR file"
                )

        else:
            try:
                while True:
                    # FIXME: This cast hides a lack of dynamic type checking
                    loaded = cast(
                        dict[Union[bytes, str], Any],
                        tnetstring.load(self.fo),
                    )
                    try:
                        if not isinstance(loaded, dict):
                            raise ValueError(f"Invalid flow: {loaded=}")
                        yield flow.Flow.from_state(compat.migrate_flow(loaded))
                    except ValueError as e:
                        raise exceptions.FlowReadException(e) from e
            except (ValueError, TypeError, IndexError) as e:
                if str(e) == "not a tnetstring: empty file":
                    return  # Error is due to EOF
                raise exceptions.FlowReadException("Invalid data format.") from e


class FilteredFlowWriter: