second commit

env/lib/python3.11/site-packages/websockets/legacy/http.py

@@ -0,0 +1,201 @@
+from __future__ import annotations
+
+import asyncio
+import os
+import re
+
+from ..datastructures import Headers
+from ..exceptions import SecurityError
+
+
+__all__ = ["read_request", "read_response"]
+
+MAX_NUM_HEADERS = int(os.environ.get("WEBSOCKETS_MAX_NUM_HEADERS", "128"))
+MAX_LINE_LENGTH = int(os.environ.get("WEBSOCKETS_MAX_LINE_LENGTH", "8192"))
+
+
+def d(value: bytes) -> str:
+    """
+    Decode a bytestring for interpolating into an error message.
+
+    """
+    return value.decode(errors="backslashreplace")
+
+
+# See https://datatracker.ietf.org/doc/html/rfc7230#appendix-B.
+
+# Regex for validating header names.
+
+_token_re = re.compile(rb"[-!#$%&\'*+.^_`|~0-9a-zA-Z]+")
+
+# Regex for validating header values.
+
+# We don't attempt to support obsolete line folding.
+
+# Include HTAB (\x09), SP (\x20), VCHAR (\x21-\x7e), obs-text (\x80-\xff).
+
+# The ABNF is complicated because it attempts to express that optional
+# whitespace is ignored. We strip whitespace and don't revalidate that.
+
+# See also https://www.rfc-editor.org/errata_search.php?rfc=7230&eid=4189
+
+_value_re = re.compile(rb"[\x09\x20-\x7e\x80-\xff]*")
+
+
+async def read_request(stream: asyncio.StreamReader) -> tuple[str, Headers]:
+    """
+    Read an HTTP/1.1 GET request and return ``(path, headers)``.
+
+    ``path`` isn't URL-decoded or validated in any way.
+
+    ``path`` and ``headers`` are expected to contain only ASCII characters.
+    Other characters are represented with surrogate escapes.
+
+    :func:`read_request` doesn't attempt to read the request body because
+    WebSocket handshake requests don't have one. If the request contains a
+    body, it may be read from ``stream`` after this coroutine returns.
+
+    Args:
+        stream: Input to read the request from.
+
+    Raises:
+        EOFError: If the connection is closed without a full HTTP request.
+        SecurityError: If the request exceeds a security limit.
+        ValueError: If the request isn't well formatted.
+
+    """
+    # https://datatracker.ietf.org/doc/html/rfc7230#section-3.1.1
+
+    # Parsing is simple because fixed values are expected for method and
+    # version and because path isn't checked. Since WebSocket software tends
+    # to implement HTTP/1.1 strictly, there's little need for lenient parsing.
+
+    try:
+        request_line = await read_line(stream)
+    except EOFError as exc:
+        raise EOFError("connection closed while reading HTTP request line") from exc
+
+    try:
+        method, raw_path, version = request_line.split(b" ", 2)
+    except ValueError:  # not enough values to unpack (expected 3, got 1-2)
+        raise ValueError(f"invalid HTTP request line: {d(request_line)}") from None
+
+    if method != b"GET":
+        raise ValueError(f"unsupported HTTP method: {d(method)}")
+    if version != b"HTTP/1.1":
+        raise ValueError(f"unsupported HTTP version: {d(version)}")
+    path = raw_path.decode("ascii", "surrogateescape")
+
+    headers = await read_headers(stream)
+
+    return path, headers
+
+
+async def read_response(stream: asyncio.StreamReader) -> tuple[int, str, Headers]:
+    """
+    Read an HTTP/1.1 response and return ``(status_code, reason, headers)``.
+
+    ``reason`` and ``headers`` are expected to contain only ASCII characters.
+    Other characters are represented with surrogate escapes.
+
+    :func:`read_request` doesn't attempt to read the response body because
+    WebSocket handshake responses don't have one. If the response contains a
+    body, it may be read from ``stream`` after this coroutine returns.
+
+    Args:
+        stream: Input to read the response from.
+
+    Raises:
+        EOFError: If the connection is closed without a full HTTP response.
+        SecurityError: If the response exceeds a security limit.
+        ValueError: If the response isn't well formatted.
+
+    """
+    # https://datatracker.ietf.org/doc/html/rfc7230#section-3.1.2
+
+    # As in read_request, parsing is simple because a fixed value is expected
+    # for version, status_code is a 3-digit number, and reason can be ignored.
+
+    try:
+        status_line = await read_line(stream)
+    except EOFError as exc:
+        raise EOFError("connection closed while reading HTTP status line") from exc
+
+    try:
+        version, raw_status_code, raw_reason = status_line.split(b" ", 2)
+    except ValueError:  # not enough values to unpack (expected 3, got 1-2)
+        raise ValueError(f"invalid HTTP status line: {d(status_line)}") from None
+
+    if version != b"HTTP/1.1":
+        raise ValueError(f"unsupported HTTP version: {d(version)}")
+    try:
+        status_code = int(raw_status_code)
+    except ValueError:  # invalid literal for int() with base 10
+        raise ValueError(f"invalid HTTP status code: {d(raw_status_code)}") from None
+    if not 100 <= status_code < 1000:
+        raise ValueError(f"unsupported HTTP status code: {d(raw_status_code)}")
+    if not _value_re.fullmatch(raw_reason):
+        raise ValueError(f"invalid HTTP reason phrase: {d(raw_reason)}")
+    reason = raw_reason.decode()
+
+    headers = await read_headers(stream)
+
+    return status_code, reason, headers
+
+
+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:
+    """
+    Read a single line from ``stream``.
+
+    CRLF is stripped from the return value.
+
+    """
+    # Security: this is bounded by the StreamReader's limit (default = 32 KiB).
+    line = await stream.readline()
+    # Security: this guarantees header values are small (hard-coded = 8 KiB)
+    if len(line) > MAX_LINE_LENGTH:
+        raise SecurityError("line too long")
+    # Not mandatory but safe - https://datatracker.ietf.org/doc/html/rfc7230#section-3.5
+    if not line.endswith(b"\r\n"):
+        raise EOFError("line without CRLF")
+    return line[:-2]