Source code for w3lib.url

"""
This module contains general purpose URL functions not found in the standard
library.
"""
import base64
import codecs
import os
import re
import posixpath
import warnings
import string
from collections import namedtuple
import six
from six.moves.urllib.parse import (urljoin, urlsplit, urlunsplit,
                                    urldefrag, urlencode, urlparse,
                                    quote, parse_qs, parse_qsl,
                                    ParseResult, unquote, urlunparse)
from six.moves.urllib.request import pathname2url, url2pathname
from w3lib.util import to_bytes, to_native_str, to_unicode


# error handling function for bytes-to-Unicode decoding errors with URLs
def _quote_byte(error):
    return (to_unicode(quote(error.object[error.start:error.end])), error.end)

codecs.register_error('percentencode', _quote_byte)

# constants from RFC 3986, Section 2.2 and 2.3
RFC3986_GEN_DELIMS = b':/?#[]@'
RFC3986_SUB_DELIMS = b"!$&'()*+,;="
RFC3986_RESERVED = RFC3986_GEN_DELIMS + RFC3986_SUB_DELIMS
RFC3986_UNRESERVED = (string.ascii_letters + string.digits + "-._~").encode('ascii')
EXTRA_SAFE_CHARS = b'|'  # see https://github.com/scrapy/w3lib/pull/25

_safe_chars = RFC3986_RESERVED + RFC3986_UNRESERVED + EXTRA_SAFE_CHARS + b'%'

_ascii_tab_newline_re = re.compile(r'[\t\n\r]')  # see https://infra.spec.whatwg.org/#ascii-tab-or-newline

[docs]def safe_url_string(url, encoding='utf8', path_encoding='utf8', quote_path=True): """Convert the given URL into a legal URL by escaping unsafe characters according to RFC-3986. Also, ASCII tabs and newlines are removed as per https://url.spec.whatwg.org/#url-parsing. If a bytes URL is given, it is first converted to `str` using the given encoding (which defaults to 'utf-8'). If quote_path is True (default), path_encoding ('utf-8' by default) is used to encode URL path component which is then quoted. Otherwise, if quote_path is False, path component is not encoded or quoted. Given encoding is used for query string or form data. When passing an encoding, you should use the encoding of the original page (the page from which the URL was extracted from). Calling this function on an already "safe" URL will return the URL unmodified. Always returns a native `str` (bytes in Python2, unicode in Python3). """ # Python3's urlsplit() chokes on bytes input with non-ASCII chars, # so let's decode (to Unicode) using page encoding: # - it is assumed that a raw bytes input comes from a document # encoded with the supplied encoding (or UTF8 by default) # - if the supplied (or default) encoding chokes, # percent-encode offending bytes decoded = to_unicode(url, encoding=encoding, errors='percentencode') parts = urlsplit(_ascii_tab_newline_re.sub('', decoded)) # IDNA encoding can fail for too long labels (>63 characters) # or missing labels (e.g. http://.example.com) try: netloc = parts.netloc.encode('idna') except UnicodeError: netloc = parts.netloc # default encoding for path component SHOULD be UTF-8 if quote_path: path = quote(to_bytes(parts.path, path_encoding), _safe_chars) else: path = to_native_str(parts.path) # quote() in Python2 return type follows input type; # quote() in Python3 always returns Unicode (native str) return urlunsplit(( to_native_str(parts.scheme), to_native_str(netloc).rstrip(':'), path, # encoding of query and fragment follows page encoding # or form-charset (if known and passed) quote(to_bytes(parts.query, encoding), _safe_chars), quote(to_bytes(parts.fragment, encoding), _safe_chars), ))
_parent_dirs = re.compile(r'/?(\.\./)+')
[docs]def safe_download_url(url, encoding='utf8', path_encoding='utf8'): """ Make a url for download. This will call safe_url_string and then strip the fragment, if one exists. The path will be normalised. If the path is outside the document root, it will be changed to be within the document root. """ safe_url = safe_url_string(url, encoding, path_encoding) scheme, netloc, path, query, _ = urlsplit(safe_url) if path: path = _parent_dirs.sub('', posixpath.normpath(path)) if safe_url.endswith('/') and not path.endswith('/'): path += '/' else: path = '/' return urlunsplit((scheme, netloc, path, query, ''))
def is_url(text): return text.partition("://")[0] in ('file', 'http', 'https')
[docs]def url_query_parameter(url, parameter, default=None, keep_blank_values=0): """Return the value of a url parameter, given the url and parameter name General case: >>> import w3lib.url >>> w3lib.url.url_query_parameter("product.html?id=200&foo=bar", "id") '200' >>> Return a default value if the parameter is not found: >>> w3lib.url.url_query_parameter("product.html?id=200&foo=bar", "notthere", "mydefault") 'mydefault' >>> Returns None if `keep_blank_values` not set or 0 (default): >>> w3lib.url.url_query_parameter("product.html?id=", "id") >>> Returns an empty string if `keep_blank_values` set to 1: >>> w3lib.url.url_query_parameter("product.html?id=", "id", keep_blank_values=1) '' >>> """ queryparams = parse_qs( urlsplit(str(url))[3], keep_blank_values=keep_blank_values ) return queryparams.get(parameter, [default])[0]
[docs]def url_query_cleaner(url, parameterlist=(), sep='&', kvsep='=', remove=False, unique=True, keep_fragments=False): """Clean URL arguments leaving only those passed in the parameterlist keeping order >>> import w3lib.url >>> w3lib.url.url_query_cleaner("product.html?id=200&foo=bar&name=wired", ('id',)) 'product.html?id=200' >>> w3lib.url.url_query_cleaner("product.html?id=200&foo=bar&name=wired", ['id', 'name']) 'product.html?id=200&name=wired' >>> If `unique` is ``False``, do not remove duplicated keys >>> w3lib.url.url_query_cleaner("product.html?d=1&e=b&d=2&d=3&other=other", ['d'], unique=False) 'product.html?d=1&d=2&d=3' >>> If `remove` is ``True``, leave only those **not in parameterlist**. >>> w3lib.url.url_query_cleaner("product.html?id=200&foo=bar&name=wired", ['id'], remove=True) 'product.html?foo=bar&name=wired' >>> w3lib.url.url_query_cleaner("product.html?id=2&foo=bar&name=wired", ['id', 'foo'], remove=True) 'product.html?name=wired' >>> By default, URL fragments are removed. If you need to preserve fragments, pass the ``keep_fragments`` argument as ``True``. >>> w3lib.url.url_query_cleaner('http://domain.tld/?bla=123#123123', ['bla'], remove=True, keep_fragments=True) 'http://domain.tld/#123123' """ if isinstance(parameterlist, (six.text_type, bytes)): parameterlist = [parameterlist] url, fragment = urldefrag(url) base, _, query = url.partition('?') seen = set() querylist = [] for ksv in query.split(sep): if not ksv: continue k, _, _ = ksv.partition(kvsep) if unique and k in seen: continue elif remove and k in parameterlist: continue elif not remove and k not in parameterlist: continue else: querylist.append(ksv) seen.add(k) url = '?'.join([base, sep.join(querylist)]) if querylist else base if keep_fragments: url += '#' + fragment return url
def _add_or_replace_parameters(url, params): parsed = urlsplit(url) current_args = parse_qsl(parsed.query, keep_blank_values=True) new_args = [] seen_params = set() for name, value in current_args: if name not in params: new_args.append((name, value)) elif name not in seen_params: new_args.append((name, params[name])) seen_params.add(name) not_modified_args = [(name, value) for name, value in params.items() if name not in seen_params] new_args += not_modified_args query = urlencode(new_args) return urlunsplit(parsed._replace(query=query))
[docs]def add_or_replace_parameter(url, name, new_value): """Add or remove a parameter to a given url >>> import w3lib.url >>> w3lib.url.add_or_replace_parameter('http://www.example.com/index.php', 'arg', 'v') 'http://www.example.com/index.php?arg=v' >>> w3lib.url.add_or_replace_parameter('http://www.example.com/index.php?arg1=v1&arg2=v2&arg3=v3', 'arg4', 'v4') 'http://www.example.com/index.php?arg1=v1&arg2=v2&arg3=v3&arg4=v4' >>> w3lib.url.add_or_replace_parameter('http://www.example.com/index.php?arg1=v1&arg2=v2&arg3=v3', 'arg3', 'v3new') 'http://www.example.com/index.php?arg1=v1&arg2=v2&arg3=v3new' >>> """ return _add_or_replace_parameters(url, {name: new_value})
[docs]def add_or_replace_parameters(url, new_parameters): """Add or remove a parameters to a given url >>> import w3lib.url >>> w3lib.url.add_or_replace_parameters('http://www.example.com/index.php', {'arg': 'v'}) 'http://www.example.com/index.php?arg=v' >>> args = {'arg4': 'v4', 'arg3': 'v3new'} >>> w3lib.url.add_or_replace_parameters('http://www.example.com/index.php?arg1=v1&arg2=v2&arg3=v3', args) 'http://www.example.com/index.php?arg1=v1&arg2=v2&arg3=v3new&arg4=v4' >>> """ return _add_or_replace_parameters(url, new_parameters)
[docs]def path_to_file_uri(path): """Convert local filesystem path to legal File URIs as described in: http://en.wikipedia.org/wiki/File_URI_scheme """ x = pathname2url(os.path.abspath(path)) if os.name == 'nt': x = x.replace('|', ':') # http://bugs.python.org/issue5861 return 'file:///%s' % x.lstrip('/')
[docs]def file_uri_to_path(uri): """Convert File URI to local filesystem path according to: http://en.wikipedia.org/wiki/File_URI_scheme """ uri_path = urlparse(uri).path return url2pathname(uri_path)
[docs]def any_to_uri(uri_or_path): """If given a path name, return its File URI, otherwise return it unmodified """ if os.path.splitdrive(uri_or_path)[0]: return path_to_file_uri(uri_or_path) u = urlparse(uri_or_path) return uri_or_path if u.scheme else path_to_file_uri(uri_or_path)
# ASCII characters. _char = set(map(chr, range(127))) # RFC 2045 token. _token = r'[{}]+'.format(re.escape(''.join(_char - # Control characters. set(map(chr, range(0, 32))) - # tspecials and space. set('()<>@,;:\\"/[]?= ')))) # RFC 822 quoted-string, without surrounding quotation marks. _quoted_string = r'(?:[{}]|(?:\\[{}]))*'.format( re.escape(''.join(_char - {'"', '\\', '\r'})), re.escape(''.join(_char)) ) # Encode the regular expression strings to make them into bytes, as Python 3 # bytes have no format() method, but bytes must be passed to re.compile() in # order to make a pattern object that can be used to match on bytes. # RFC 2397 mediatype. _mediatype_pattern = re.compile( r'{token}/{token}'.format(token=_token).encode() ) _mediatype_parameter_pattern = re.compile( r';({token})=(?:({token})|"({quoted})")'.format(token=_token, quoted=_quoted_string ).encode() ) _ParseDataURIResult = namedtuple("ParseDataURIResult", "media_type media_type_parameters data")
[docs]def parse_data_uri(uri): """ Parse a data: URI, returning a 3-tuple of media type, dictionary of media type parameters, and data. """ if not isinstance(uri, bytes): uri = safe_url_string(uri).encode('ascii') try: scheme, uri = uri.split(b':', 1) except ValueError: raise ValueError("invalid URI") if scheme.lower() != b'data': raise ValueError("not a data URI") # RFC 3986 section 2.1 allows percent encoding to escape characters that # would be interpreted as delimiters, implying that actual delimiters # should not be percent-encoded. # Decoding before parsing will allow malformed URIs with percent-encoded # delimiters, but it makes parsing easier and should not affect # well-formed URIs, as the delimiters used in this URI scheme are not # allowed, percent-encoded or not, in tokens. if six.PY2: uri = unquote(uri) else: uri = unquote_to_bytes(uri) media_type = "text/plain" media_type_params = {} m = _mediatype_pattern.match(uri) if m: media_type = m.group().decode() uri = uri[m.end():] else: media_type_params['charset'] = "US-ASCII" while True: m = _mediatype_parameter_pattern.match(uri) if m: attribute, value, value_quoted = m.groups() if value_quoted: value = re.sub(br'\\(.)', r'\1', value_quoted) media_type_params[attribute.decode()] = value.decode() uri = uri[m.end():] else: break try: is_base64, data = uri.split(b',', 1) except ValueError: raise ValueError("invalid data URI") if is_base64: if is_base64 != b";base64": raise ValueError("invalid data URI") data = base64.b64decode(data) return _ParseDataURIResult(media_type, media_type_params, data)
__all__ = ["add_or_replace_parameter", "add_or_replace_parameters", "any_to_uri", "canonicalize_url", "file_uri_to_path", "is_url", "parse_data_uri", "path_to_file_uri", "safe_download_url", "safe_url_string", "url_query_cleaner", "url_query_parameter", # this last one is deprecated ; include it to be on the safe side "urljoin_rfc"] def _safe_ParseResult(parts, encoding='utf8', path_encoding='utf8'): # IDNA encoding can fail for too long labels (>63 characters) # or missing labels (e.g. http://.example.com) try: netloc = parts.netloc.encode('idna') except UnicodeError: netloc = parts.netloc return ( to_native_str(parts.scheme), to_native_str(netloc), # default encoding for path component SHOULD be UTF-8 quote(to_bytes(parts.path, path_encoding), _safe_chars), quote(to_bytes(parts.params, path_encoding), _safe_chars), # encoding of query and fragment follows page encoding # or form-charset (if known and passed) quote(to_bytes(parts.query, encoding), _safe_chars), quote(to_bytes(parts.fragment, encoding), _safe_chars) )
[docs]def canonicalize_url(url, keep_blank_values=True, keep_fragments=False, encoding=None): r"""Canonicalize the given url by applying the following procedures: - sort query arguments, first by key, then by value - percent encode paths ; non-ASCII characters are percent-encoded using UTF-8 (RFC-3986) - percent encode query arguments ; non-ASCII characters are percent-encoded using passed `encoding` (UTF-8 by default) - normalize all spaces (in query arguments) '+' (plus symbol) - normalize percent encodings case (%2f -> %2F) - remove query arguments with blank values (unless `keep_blank_values` is True) - remove fragments (unless `keep_fragments` is True) The url passed can be bytes or unicode, while the url returned is always a native str (bytes in Python 2, unicode in Python 3). >>> import w3lib.url >>> >>> # sorting query arguments >>> w3lib.url.canonicalize_url('http://www.example.com/do?c=3&b=5&b=2&a=50') 'http://www.example.com/do?a=50&b=2&b=5&c=3' >>> >>> # UTF-8 conversion + percent-encoding of non-ASCII characters >>> w3lib.url.canonicalize_url(u'http://www.example.com/r\u00e9sum\u00e9') 'http://www.example.com/r%C3%A9sum%C3%A9' >>> For more examples, see the tests in `tests/test_url.py`. """ # If supplied `encoding` is not compatible with all characters in `url`, # fallback to UTF-8 as safety net. # UTF-8 can handle all Unicode characters, # so we should be covered regarding URL normalization, # if not for proper URL expected by remote website. try: scheme, netloc, path, params, query, fragment = _safe_ParseResult( parse_url(url), encoding=encoding) except UnicodeEncodeError as e: scheme, netloc, path, params, query, fragment = _safe_ParseResult( parse_url(url), encoding='utf8') # 1. decode query-string as UTF-8 (or keep raw bytes), # sort values, # and percent-encode them back if six.PY2: keyvals = parse_qsl(query, keep_blank_values) else: # Python3's urllib.parse.parse_qsl does not work as wanted # for percent-encoded characters that do not match passed encoding, # they get lost. # # e.g., 'q=b%a3' becomes [('q', 'b\ufffd')] # (ie. with 'REPLACEMENT CHARACTER' (U+FFFD), # instead of \xa3 that you get with Python2's parse_qsl) # # what we want here is to keep raw bytes, and percent encode them # so as to preserve whatever encoding what originally used. # # See https://tools.ietf.org/html/rfc3987#section-6.4: # # For example, it is possible to have a URI reference of # "http://www.example.org/r%E9sum%E9.xml#r%C3%A9sum%C3%A9", where the # document name is encoded in iso-8859-1 based on server settings, but # where the fragment identifier is encoded in UTF-8 according to # [XPointer]. The IRI corresponding to the above URI would be (in XML # notation) # "http://www.example.org/r%E9sum%E9.xml#r&#xE9;sum&#xE9;". # Similar considerations apply to query parts. The functionality of # IRIs (namely, to be able to include non-ASCII characters) can only be # used if the query part is encoded in UTF-8. keyvals = parse_qsl_to_bytes(query, keep_blank_values) keyvals.sort() query = urlencode(keyvals) # 2. decode percent-encoded sequences in path as UTF-8 (or keep raw bytes) # and percent-encode path again (this normalizes to upper-case %XX) uqp = _unquotepath(path) path = quote(uqp, _safe_chars) or '/' fragment = '' if not keep_fragments else fragment # every part should be safe already return urlunparse((scheme, netloc.lower().rstrip(':'), path, params, query, fragment))
def _unquotepath(path): for reserved in ('2f', '2F', '3f', '3F'): path = path.replace('%' + reserved, '%25' + reserved.upper()) if six.PY2: # in Python 2, '%a3' becomes '\xa3', which is what we want return unquote(path) else: # in Python 3, # standard lib's unquote() does not work for non-UTF-8 # percent-escaped characters, they get lost. # e.g., '%a3' becomes 'REPLACEMENT CHARACTER' (U+FFFD) # # unquote_to_bytes() returns raw bytes instead return unquote_to_bytes(path) def parse_url(url, encoding=None): """Return urlparsed url from the given argument (which could be an already parsed url) """ if isinstance(url, ParseResult): return url return urlparse(to_unicode(url, encoding)) if not six.PY2: from urllib.parse import _coerce_args, unquote_to_bytes def parse_qsl_to_bytes(qs, keep_blank_values=False): """Parse a query given as a string argument. Data are returned as a list of name, value pairs as bytes. Arguments: qs: percent-encoded query string to be parsed keep_blank_values: flag indicating whether blank values in percent-encoded queries should be treated as blank strings. A true value indicates that blanks should be retained as blank strings. The default false value indicates that blank values are to be ignored and treated as if they were not included. """ # This code is the same as Python3's parse_qsl() # (at https://hg.python.org/cpython/rev/c38ac7ab8d9a) # except for the unquote(s, encoding, errors) calls replaced # with unquote_to_bytes(s) qs, _coerce_result = _coerce_args(qs) pairs = [s2 for s1 in qs.split('&') for s2 in s1.split(';')] r = [] for name_value in pairs: if not name_value: continue nv = name_value.split('=', 1) if len(nv) != 2: # Handle case of a control-name with no equal sign if keep_blank_values: nv.append('') else: continue if len(nv[1]) or keep_blank_values: name = nv[0].replace('+', ' ') name = unquote_to_bytes(name) name = _coerce_result(name) value = nv[1].replace('+', ' ') value = unquote_to_bytes(value) value = _coerce_result(value) r.append((name, value)) return r
[docs]def urljoin_rfc(base, ref, encoding='utf-8'): r""" .. warning:: This function is deprecated and will be removed in future. It is not supported with Python 3. Please use ``urlparse.urljoin`` instead. Same as urlparse.urljoin but supports unicode values in base and ref parameters (in which case they will be converted to str using the given encoding). Always returns a str. >>> import w3lib.url >>> w3lib.url.urljoin_rfc('http://www.example.com/path/index.html', u'/otherpath/index2.html') 'http://www.example.com/otherpath/index2.html' >>> >>> # Note: the following does not work in Python 3 >>> w3lib.url.urljoin_rfc(b'http://www.example.com/path/index.html', u'fran\u00e7ais/d\u00e9part.htm') # doctest: +SKIP 'http://www.example.com/path/fran\xc3\xa7ais/d\xc3\xa9part.htm' >>> """ warnings.warn("w3lib.url.urljoin_rfc is deprecated, use urlparse.urljoin instead", DeprecationWarning) str_base = to_bytes(base, encoding) str_ref = to_bytes(ref, encoding) return urljoin(str_base, str_ref)