197 lines
7.0 KiB
Python
197 lines
7.0 KiB
Python
import re
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from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
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from urllib.parse import unquote
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from sanic.helpers import STATUS_CODES
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# TODO:
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# - the Options object should be a typed object to allow for less casting
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# across the application (in request.py for example)
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HeaderIterable = Iterable[Tuple[str, Any]] # Values convertible to str
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HeaderBytesIterable = Iterable[Tuple[bytes, bytes]]
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Options = Dict[str, Union[int, str]] # key=value fields in various headers
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OptionsIterable = Iterable[Tuple[str, str]] # May contain duplicate keys
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_token, _quoted = r"([\w!#$%&'*+\-.^_`|~]+)", r'"([^"]*)"'
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_param = re.compile(fr";\s*{_token}=(?:{_token}|{_quoted})", re.ASCII)
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_firefox_quote_escape = re.compile(r'\\"(?!; |\s*$)')
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_ipv6 = "(?:[0-9A-Fa-f]{0,4}:){2,7}[0-9A-Fa-f]{0,4}"
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_ipv6_re = re.compile(_ipv6)
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_host_re = re.compile(
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r"((?:\[" + _ipv6 + r"\])|[a-zA-Z0-9.\-]{1,253})(?::(\d{1,5}))?"
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)
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# RFC's quoted-pair escapes are mostly ignored by browsers. Chrome, Firefox and
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# curl all have different escaping, that we try to handle as well as possible,
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# even though no client espaces in a way that would allow perfect handling.
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# For more information, consult ../tests/test_requests.py
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def parse_content_header(value: str) -> Tuple[str, Options]:
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"""Parse content-type and content-disposition header values.
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E.g. 'form-data; name=upload; filename=\"file.txt\"' to
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('form-data', {'name': 'upload', 'filename': 'file.txt'})
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Mostly identical to cgi.parse_header and werkzeug.parse_options_header
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but runs faster and handles special characters better. Unescapes quotes.
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"""
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value = _firefox_quote_escape.sub("%22", value)
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pos = value.find(";")
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if pos == -1:
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options: Dict[str, Union[int, str]] = {}
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else:
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options = {
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m.group(1).lower(): m.group(2) or m.group(3).replace("%22", '"')
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for m in _param.finditer(value[pos:])
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}
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value = value[:pos]
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return value.strip().lower(), options
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# https://tools.ietf.org/html/rfc7230#section-3.2.6 and
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# https://tools.ietf.org/html/rfc7239#section-4
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# This regex is for *reversed* strings because that works much faster for
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# right-to-left matching than the other way around. Be wary that all things are
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# a bit backwards! _rparam matches forwarded pairs alike ";key=value"
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_rparam = re.compile(f"(?:{_token}|{_quoted})={_token}\\s*($|[;,])", re.ASCII)
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def parse_forwarded(headers, config) -> Optional[Options]:
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"""Parse RFC 7239 Forwarded headers.
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The value of `by` or `secret` must match `config.FORWARDED_SECRET`
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:return: dict with keys and values, or None if nothing matched
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"""
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header = headers.getall("forwarded", None)
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secret = config.FORWARDED_SECRET
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if header is None or not secret:
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return None
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header = ",".join(header) # Join multiple header lines
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if secret not in header:
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return None
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# Loop over <separator><key>=<value> elements from right to left
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sep = pos = None
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options: List[Tuple[str, str]] = []
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found = False
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for m in _rparam.finditer(header[::-1]):
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# Start of new element? (on parser skips and non-semicolon right sep)
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if m.start() != pos or sep != ";":
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# Was the previous element (from right) what we wanted?
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if found:
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break
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# Clear values and parse as new element
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del options[:]
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pos = m.end()
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val_token, val_quoted, key, sep = m.groups()
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key = key.lower()[::-1]
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val = (val_token or val_quoted.replace('"\\', '"'))[::-1]
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options.append((key, val))
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if key in ("secret", "by") and val == secret:
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found = True
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# Check if we would return on next round, to avoid useless parse
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if found and sep != ";":
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break
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# If secret was found, return the matching options in left-to-right order
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return fwd_normalize(reversed(options)) if found else None
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def parse_xforwarded(headers, config) -> Optional[Options]:
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"""Parse traditional proxy headers."""
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real_ip_header = config.REAL_IP_HEADER
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proxies_count = config.PROXIES_COUNT
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addr = real_ip_header and headers.get(real_ip_header)
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if not addr and proxies_count:
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assert proxies_count > 0
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try:
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# Combine, split and filter multiple headers' entries
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forwarded_for = headers.getall(config.FORWARDED_FOR_HEADER)
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proxies = [
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p
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for p in (
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p.strip() for h in forwarded_for for p in h.split(",")
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)
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if p
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]
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addr = proxies[-proxies_count]
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except (KeyError, IndexError):
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pass
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# No processing of other headers if no address is found
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if not addr:
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return None
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def options():
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yield "for", addr
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for key, header in (
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("proto", "x-scheme"),
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("proto", "x-forwarded-proto"), # Overrides X-Scheme if present
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("host", "x-forwarded-host"),
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("port", "x-forwarded-port"),
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("path", "x-forwarded-path"),
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):
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yield key, headers.get(header)
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return fwd_normalize(options())
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def fwd_normalize(fwd: OptionsIterable) -> Options:
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"""Normalize and convert values extracted from forwarded headers."""
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ret: Dict[str, Union[int, str]] = {}
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for key, val in fwd:
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if val is not None:
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try:
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if key in ("by", "for"):
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ret[key] = fwd_normalize_address(val)
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elif key in ("host", "proto"):
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ret[key] = val.lower()
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elif key == "port":
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ret[key] = int(val)
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elif key == "path":
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ret[key] = unquote(val)
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else:
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ret[key] = val
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except ValueError:
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pass
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return ret
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def fwd_normalize_address(addr: str) -> str:
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"""Normalize address fields of proxy headers."""
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if addr == "unknown":
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raise ValueError() # omit unknown value identifiers
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if addr.startswith("_"):
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return addr # do not lower-case obfuscated strings
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if _ipv6_re.fullmatch(addr):
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addr = f"[{addr}]" # bracket IPv6
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return addr.lower()
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def parse_host(host: str) -> Tuple[Optional[str], Optional[int]]:
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"""Split host:port into hostname and port.
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:return: None in place of missing elements
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"""
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m = _host_re.fullmatch(host)
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if not m:
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return None, None
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host, port = m.groups()
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return host.lower(), int(port) if port is not None else None
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_HTTP1_STATUSLINES = [
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b"HTTP/1.1 %d %b\r\n" % (status, STATUS_CODES.get(status, b"UNKNOWN"))
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for status in range(1000)
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]
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def format_http1_response(status: int, headers: HeaderBytesIterable) -> bytes:
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"""Format a HTTP/1.1 response header."""
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# Note: benchmarks show that here bytes concat is faster than bytearray,
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# b"".join() or %-formatting. %timeit any changes you make.
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ret = _HTTP1_STATUSLINES[status]
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for h in headers:
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ret += b"%b: %b\r\n" % h
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ret += b"\r\n"
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return ret
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