Function read_headers

src/websockets/legacy/http.py:146–183

Read HTTP headers from ``stream``. Non-ASCII characters are represented with surrogate escapes.

(stream: asyncio.StreamReader)

async def read_headers(stream: asyncio.StreamReader) -> Headers:
    """
    Read HTTP headers from ``stream``.

    Non-ASCII characters are represented with surrogate escapes.

    """
    # https://datatracker.ietf.org/doc/html/rfc7230#section-3.2

    # We don't attempt to support obsolete line folding.

    headers = Headers()
    for _ in range(MAX_NUM_HEADERS + 1):
        try:
            line = await read_line(stream)
        except EOFError as exc:
            raise EOFError("connection closed while reading HTTP headers") from exc
        if line == b"":
            break

        try:
            raw_name, raw_value = line.split(b":", 1)
        except ValueError:  # not enough values to unpack (expected 2, got 1)
            raise ValueError(f"invalid HTTP header line: {d(line)}") from None
        if not _token_re.fullmatch(raw_name):
            raise ValueError(f"invalid HTTP header name: {d(raw_name)}")
        raw_value = raw_value.strip(b" \t")
        if not _value_re.fullmatch(raw_value):
            raise ValueError(f"invalid HTTP header value: {d(raw_value)}")

        name = raw_name.decode("ascii")  # guaranteed to be ASCII at this point
        value = raw_value.decode("ascii", "surrogateescape")
        headers[name] = value

    else:
        raise SecurityError("too many HTTP headers")

    return headers


async def read_line(stream: asyncio.StreamReader) -> bytes: