|
- """
- An implementation of `urlparse` that provides URL validation and normalization
- as described by RFC3986.
-
- We rely on this implementation rather than the one in Python's stdlib, because:
-
- * It provides more complete URL validation.
- * It properly differentiates between an empty querystring and an absent querystring,
- to distinguish URLs with a trailing '?'.
- * It handles scheme, hostname, port, and path normalization.
- * It supports IDNA hostnames, normalizing them to their encoded form.
- * The API supports passing individual components, as well as the complete URL string.
-
- Previously we relied on the excellent `rfc3986` package to handle URL parsing and
- validation, but this module provides a simpler alternative, with less indirection
- required.
- """
-
- from __future__ import annotations
-
- import ipaddress
- import re
- import typing
-
- import idna
-
- from ._exceptions import InvalidURL
-
- MAX_URL_LENGTH = 65536
-
- # https://datatracker.ietf.org/doc/html/rfc3986.html#section-2.3
- UNRESERVED_CHARACTERS = (
- "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
- )
- SUB_DELIMS = "!$&'()*+,;="
-
- PERCENT_ENCODED_REGEX = re.compile("%[A-Fa-f0-9]{2}")
-
- # https://url.spec.whatwg.org/#percent-encoded-bytes
-
- # The fragment percent-encode set is the C0 control percent-encode set
- # and U+0020 SPACE, U+0022 ("), U+003C (<), U+003E (>), and U+0060 (`).
- FRAG_SAFE = "".join(
- [chr(i) for i in range(0x20, 0x7F) if i not in (0x20, 0x22, 0x3C, 0x3E, 0x60)]
- )
-
- # The query percent-encode set is the C0 control percent-encode set
- # and U+0020 SPACE, U+0022 ("), U+0023 (#), U+003C (<), and U+003E (>).
- QUERY_SAFE = "".join(
- [chr(i) for i in range(0x20, 0x7F) if i not in (0x20, 0x22, 0x23, 0x3C, 0x3E)]
- )
-
- # The path percent-encode set is the query percent-encode set
- # and U+003F (?), U+0060 (`), U+007B ({), and U+007D (}).
- PATH_SAFE = "".join(
- [
- chr(i)
- for i in range(0x20, 0x7F)
- if i not in (0x20, 0x22, 0x23, 0x3C, 0x3E) + (0x3F, 0x60, 0x7B, 0x7D)
- ]
- )
-
- # The userinfo percent-encode set is the path percent-encode set
- # and U+002F (/), U+003A (:), U+003B (;), U+003D (=), U+0040 (@),
- # U+005B ([) to U+005E (^), inclusive, and U+007C (|).
- USERNAME_SAFE = "".join(
- [
- chr(i)
- for i in range(0x20, 0x7F)
- if i
- not in (0x20, 0x22, 0x23, 0x3C, 0x3E)
- + (0x3F, 0x60, 0x7B, 0x7D)
- + (0x2F, 0x3A, 0x3B, 0x3D, 0x40, 0x5B, 0x5C, 0x5D, 0x5E, 0x7C)
- ]
- )
- PASSWORD_SAFE = "".join(
- [
- chr(i)
- for i in range(0x20, 0x7F)
- if i
- not in (0x20, 0x22, 0x23, 0x3C, 0x3E)
- + (0x3F, 0x60, 0x7B, 0x7D)
- + (0x2F, 0x3A, 0x3B, 0x3D, 0x40, 0x5B, 0x5C, 0x5D, 0x5E, 0x7C)
- ]
- )
- # Note... The terminology 'userinfo' percent-encode set in the WHATWG document
- # is used for the username and password quoting. For the joint userinfo component
- # we remove U+003A (:) from the safe set.
- USERINFO_SAFE = "".join(
- [
- chr(i)
- for i in range(0x20, 0x7F)
- if i
- not in (0x20, 0x22, 0x23, 0x3C, 0x3E)
- + (0x3F, 0x60, 0x7B, 0x7D)
- + (0x2F, 0x3B, 0x3D, 0x40, 0x5B, 0x5C, 0x5D, 0x5E, 0x7C)
- ]
- )
-
-
- # {scheme}: (optional)
- # //{authority} (optional)
- # {path}
- # ?{query} (optional)
- # #{fragment} (optional)
- URL_REGEX = re.compile(
- (
- r"(?:(?P<scheme>{scheme}):)?"
- r"(?://(?P<authority>{authority}))?"
- r"(?P<path>{path})"
- r"(?:\?(?P<query>{query}))?"
- r"(?:#(?P<fragment>{fragment}))?"
- ).format(
- scheme="([a-zA-Z][a-zA-Z0-9+.-]*)?",
- authority="[^/?#]*",
- path="[^?#]*",
- query="[^#]*",
- fragment=".*",
- )
- )
-
- # {userinfo}@ (optional)
- # {host}
- # :{port} (optional)
- AUTHORITY_REGEX = re.compile(
- (
- r"(?:(?P<userinfo>{userinfo})@)?" r"(?P<host>{host})" r":?(?P<port>{port})?"
- ).format(
- userinfo=".*", # Any character sequence.
- host="(\\[.*\\]|[^:@]*)", # Either any character sequence excluding ':' or '@',
- # or an IPv6 address enclosed within square brackets.
- port=".*", # Any character sequence.
- )
- )
-
-
- # If we call urlparse with an individual component, then we need to regex
- # validate that component individually.
- # Note that we're duplicating the same strings as above. Shock! Horror!!
- COMPONENT_REGEX = {
- "scheme": re.compile("([a-zA-Z][a-zA-Z0-9+.-]*)?"),
- "authority": re.compile("[^/?#]*"),
- "path": re.compile("[^?#]*"),
- "query": re.compile("[^#]*"),
- "fragment": re.compile(".*"),
- "userinfo": re.compile("[^@]*"),
- "host": re.compile("(\\[.*\\]|[^:]*)"),
- "port": re.compile(".*"),
- }
-
-
- # We use these simple regexs as a first pass before handing off to
- # the stdlib 'ipaddress' module for IP address validation.
- IPv4_STYLE_HOSTNAME = re.compile(r"^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$")
- IPv6_STYLE_HOSTNAME = re.compile(r"^\[.*\]$")
-
-
- class ParseResult(typing.NamedTuple):
- scheme: str
- userinfo: str
- host: str
- port: int | None
- path: str
- query: str | None
- fragment: str | None
-
- @property
- def authority(self) -> str:
- return "".join(
- [
- f"{self.userinfo}@" if self.userinfo else "",
- f"[{self.host}]" if ":" in self.host else self.host,
- f":{self.port}" if self.port is not None else "",
- ]
- )
-
- @property
- def netloc(self) -> str:
- return "".join(
- [
- f"[{self.host}]" if ":" in self.host else self.host,
- f":{self.port}" if self.port is not None else "",
- ]
- )
-
- def copy_with(self, **kwargs: str | None) -> ParseResult:
- if not kwargs:
- return self
-
- defaults = {
- "scheme": self.scheme,
- "authority": self.authority,
- "path": self.path,
- "query": self.query,
- "fragment": self.fragment,
- }
- defaults.update(kwargs)
- return urlparse("", **defaults)
-
- def __str__(self) -> str:
- authority = self.authority
- return "".join(
- [
- f"{self.scheme}:" if self.scheme else "",
- f"//{authority}" if authority else "",
- self.path,
- f"?{self.query}" if self.query is not None else "",
- f"#{self.fragment}" if self.fragment is not None else "",
- ]
- )
-
-
- def urlparse(url: str = "", **kwargs: str | None) -> ParseResult:
- # Initial basic checks on allowable URLs.
- # ---------------------------------------
-
- # Hard limit the maximum allowable URL length.
- if len(url) > MAX_URL_LENGTH:
- raise InvalidURL("URL too long")
-
- # If a URL includes any ASCII control characters including \t, \r, \n,
- # then treat it as invalid.
- if any(char.isascii() and not char.isprintable() for char in url):
- char = next(char for char in url if char.isascii() and not char.isprintable())
- idx = url.find(char)
- error = (
- f"Invalid non-printable ASCII character in URL, {char!r} at position {idx}."
- )
- raise InvalidURL(error)
-
- # Some keyword arguments require special handling.
- # ------------------------------------------------
-
- # Coerce "port" to a string, if it is provided as an integer.
- if "port" in kwargs:
- port = kwargs["port"]
- kwargs["port"] = str(port) if isinstance(port, int) else port
-
- # Replace "netloc" with "host and "port".
- if "netloc" in kwargs:
- netloc = kwargs.pop("netloc") or ""
- kwargs["host"], _, kwargs["port"] = netloc.partition(":")
-
- # Replace "username" and/or "password" with "userinfo".
- if "username" in kwargs or "password" in kwargs:
- username = quote(kwargs.pop("username", "") or "", safe=USERNAME_SAFE)
- password = quote(kwargs.pop("password", "") or "", safe=PASSWORD_SAFE)
- kwargs["userinfo"] = f"{username}:{password}" if password else username
-
- # Replace "raw_path" with "path" and "query".
- if "raw_path" in kwargs:
- raw_path = kwargs.pop("raw_path") or ""
- kwargs["path"], seperator, kwargs["query"] = raw_path.partition("?")
- if not seperator:
- kwargs["query"] = None
-
- # Ensure that IPv6 "host" addresses are always escaped with "[...]".
- if "host" in kwargs:
- host = kwargs.get("host") or ""
- if ":" in host and not (host.startswith("[") and host.endswith("]")):
- kwargs["host"] = f"[{host}]"
-
- # If any keyword arguments are provided, ensure they are valid.
- # -------------------------------------------------------------
-
- for key, value in kwargs.items():
- if value is not None:
- if len(value) > MAX_URL_LENGTH:
- raise InvalidURL(f"URL component '{key}' too long")
-
- # If a component includes any ASCII control characters including \t, \r, \n,
- # then treat it as invalid.
- if any(char.isascii() and not char.isprintable() for char in value):
- char = next(
- char for char in value if char.isascii() and not char.isprintable()
- )
- idx = value.find(char)
- error = (
- f"Invalid non-printable ASCII character in URL {key} component, "
- f"{char!r} at position {idx}."
- )
- raise InvalidURL(error)
-
- # Ensure that keyword arguments match as a valid regex.
- if not COMPONENT_REGEX[key].fullmatch(value):
- raise InvalidURL(f"Invalid URL component '{key}'")
-
- # The URL_REGEX will always match, but may have empty components.
- url_match = URL_REGEX.match(url)
- assert url_match is not None
- url_dict = url_match.groupdict()
-
- # * 'scheme', 'authority', and 'path' may be empty strings.
- # * 'query' may be 'None', indicating no trailing "?" portion.
- # Any string including the empty string, indicates a trailing "?".
- # * 'fragment' may be 'None', indicating no trailing "#" portion.
- # Any string including the empty string, indicates a trailing "#".
- scheme = kwargs.get("scheme", url_dict["scheme"]) or ""
- authority = kwargs.get("authority", url_dict["authority"]) or ""
- path = kwargs.get("path", url_dict["path"]) or ""
- query = kwargs.get("query", url_dict["query"])
- frag = kwargs.get("fragment", url_dict["fragment"])
-
- # The AUTHORITY_REGEX will always match, but may have empty components.
- authority_match = AUTHORITY_REGEX.match(authority)
- assert authority_match is not None
- authority_dict = authority_match.groupdict()
-
- # * 'userinfo' and 'host' may be empty strings.
- # * 'port' may be 'None'.
- userinfo = kwargs.get("userinfo", authority_dict["userinfo"]) or ""
- host = kwargs.get("host", authority_dict["host"]) or ""
- port = kwargs.get("port", authority_dict["port"])
-
- # Normalize and validate each component.
- # We end up with a parsed representation of the URL,
- # with components that are plain ASCII bytestrings.
- parsed_scheme: str = scheme.lower()
- parsed_userinfo: str = quote(userinfo, safe=USERINFO_SAFE)
- parsed_host: str = encode_host(host)
- parsed_port: int | None = normalize_port(port, scheme)
-
- has_scheme = parsed_scheme != ""
- has_authority = (
- parsed_userinfo != "" or parsed_host != "" or parsed_port is not None
- )
- validate_path(path, has_scheme=has_scheme, has_authority=has_authority)
- if has_scheme or has_authority:
- path = normalize_path(path)
-
- parsed_path: str = quote(path, safe=PATH_SAFE)
- parsed_query: str | None = None if query is None else quote(query, safe=QUERY_SAFE)
- parsed_frag: str | None = None if frag is None else quote(frag, safe=FRAG_SAFE)
-
- # The parsed ASCII bytestrings are our canonical form.
- # All properties of the URL are derived from these.
- return ParseResult(
- parsed_scheme,
- parsed_userinfo,
- parsed_host,
- parsed_port,
- parsed_path,
- parsed_query,
- parsed_frag,
- )
-
-
- def encode_host(host: str) -> str:
- if not host:
- return ""
-
- elif IPv4_STYLE_HOSTNAME.match(host):
- # Validate IPv4 hostnames like #.#.#.#
- #
- # From https://datatracker.ietf.org/doc/html/rfc3986/#section-3.2.2
- #
- # IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
- try:
- ipaddress.IPv4Address(host)
- except ipaddress.AddressValueError:
- raise InvalidURL(f"Invalid IPv4 address: {host!r}")
- return host
-
- elif IPv6_STYLE_HOSTNAME.match(host):
- # Validate IPv6 hostnames like [...]
- #
- # From https://datatracker.ietf.org/doc/html/rfc3986/#section-3.2.2
- #
- # "A host identified by an Internet Protocol literal address, version 6
- # [RFC3513] or later, is distinguished by enclosing the IP literal
- # within square brackets ("[" and "]"). This is the only place where
- # square bracket characters are allowed in the URI syntax."
- try:
- ipaddress.IPv6Address(host[1:-1])
- except ipaddress.AddressValueError:
- raise InvalidURL(f"Invalid IPv6 address: {host!r}")
- return host[1:-1]
-
- elif host.isascii():
- # Regular ASCII hostnames
- #
- # From https://datatracker.ietf.org/doc/html/rfc3986/#section-3.2.2
- #
- # reg-name = *( unreserved / pct-encoded / sub-delims )
- WHATWG_SAFE = '"`{}%|\\'
- return quote(host.lower(), safe=SUB_DELIMS + WHATWG_SAFE)
-
- # IDNA hostnames
- try:
- return idna.encode(host.lower()).decode("ascii")
- except idna.IDNAError:
- raise InvalidURL(f"Invalid IDNA hostname: {host!r}")
-
-
- def normalize_port(port: str | int | None, scheme: str) -> int | None:
- # From https://tools.ietf.org/html/rfc3986#section-3.2.3
- #
- # "A scheme may define a default port. For example, the "http" scheme
- # defines a default port of "80", corresponding to its reserved TCP
- # port number. The type of port designated by the port number (e.g.,
- # TCP, UDP, SCTP) is defined by the URI scheme. URI producers and
- # normalizers should omit the port component and its ":" delimiter if
- # port is empty or if its value would be the same as that of the
- # scheme's default."
- if port is None or port == "":
- return None
-
- try:
- port_as_int = int(port)
- except ValueError:
- raise InvalidURL(f"Invalid port: {port!r}")
-
- # See https://url.spec.whatwg.org/#url-miscellaneous
- default_port = {"ftp": 21, "http": 80, "https": 443, "ws": 80, "wss": 443}.get(
- scheme
- )
- if port_as_int == default_port:
- return None
- return port_as_int
-
-
- def validate_path(path: str, has_scheme: bool, has_authority: bool) -> None:
- """
- Path validation rules that depend on if the URL contains
- a scheme or authority component.
-
- See https://datatracker.ietf.org/doc/html/rfc3986.html#section-3.3
- """
- if has_authority:
- # If a URI contains an authority component, then the path component
- # must either be empty or begin with a slash ("/") character."
- if path and not path.startswith("/"):
- raise InvalidURL("For absolute URLs, path must be empty or begin with '/'")
-
- if not has_scheme and not has_authority:
- # If a URI does not contain an authority component, then the path cannot begin
- # with two slash characters ("//").
- if path.startswith("//"):
- raise InvalidURL("Relative URLs cannot have a path starting with '//'")
-
- # In addition, a URI reference (Section 4.1) may be a relative-path reference,
- # in which case the first path segment cannot contain a colon (":") character.
- if path.startswith(":"):
- raise InvalidURL("Relative URLs cannot have a path starting with ':'")
-
-
- def normalize_path(path: str) -> str:
- """
- Drop "." and ".." segments from a URL path.
-
- For example:
-
- normalize_path("/path/./to/somewhere/..") == "/path/to"
- """
- # Fast return when no '.' characters in the path.
- if "." not in path:
- return path
-
- components = path.split("/")
-
- # Fast return when no '.' or '..' components in the path.
- if "." not in components and ".." not in components:
- return path
-
- # https://datatracker.ietf.org/doc/html/rfc3986#section-5.2.4
- output: list[str] = []
- for component in components:
- if component == ".":
- pass
- elif component == "..":
- if output and output != [""]:
- output.pop()
- else:
- output.append(component)
- return "/".join(output)
-
-
- def PERCENT(string: str) -> str:
- return "".join([f"%{byte:02X}" for byte in string.encode("utf-8")])
-
-
- def percent_encoded(string: str, safe: str) -> str:
- """
- Use percent-encoding to quote a string.
- """
- NON_ESCAPED_CHARS = UNRESERVED_CHARACTERS + safe
-
- # Fast path for strings that don't need escaping.
- if not string.rstrip(NON_ESCAPED_CHARS):
- return string
-
- return "".join(
- [char if char in NON_ESCAPED_CHARS else PERCENT(char) for char in string]
- )
-
-
- def quote(string: str, safe: str) -> str:
- """
- Use percent-encoding to quote a string, omitting existing '%xx' escape sequences.
-
- See: https://www.rfc-editor.org/rfc/rfc3986#section-2.1
-
- * `string`: The string to be percent-escaped.
- * `safe`: A string containing characters that may be treated as safe, and do not
- need to be escaped. Unreserved characters are always treated as safe.
- See: https://www.rfc-editor.org/rfc/rfc3986#section-2.3
- """
- parts = []
- current_position = 0
- for match in re.finditer(PERCENT_ENCODED_REGEX, string):
- start_position, end_position = match.start(), match.end()
- matched_text = match.group(0)
- # Add any text up to the '%xx' escape sequence.
- if start_position != current_position:
- leading_text = string[current_position:start_position]
- parts.append(percent_encoded(leading_text, safe=safe))
-
- # Add the '%xx' escape sequence.
- parts.append(matched_text)
- current_position = end_position
-
- # Add any text after the final '%xx' escape sequence.
- if current_position != len(string):
- trailing_text = string[current_position:]
- parts.append(percent_encoded(trailing_text, safe=safe))
-
- return "".join(parts)
|