def whereIsYadis(resp):
"""Given a HTTPResponse, return the location of the Yadis document.
May be the URL just retrieved, another URL, or None, if I can't
find any.
[non-blocking]
@returns: str or None
"""
# Attempt to find out where to go to discover the document
# or if we already have it
content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if (content_type
and content_type.split(';', 1)[0].lower() == YADIS_CONTENT_TYPE):
return resp.final_url
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
try:
yadis_loc = findHTMLMeta(StringIO(resp.body))
except MetaNotFound:
pass
return yadis_loc
def whereIsYadis(resp):
"""Given a HTTPResponse, return the location of the Yadis document.
May be the URL just retrieved, another URL, or None, if I can't
find any.
[non-blocking]
@returns: str or None
"""
# Attempt to find out where to go to discover the document
# or if we already have it
content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if (content_type and
content_type.split(';', 1)[0].lower() == YADIS_CONTENT_TYPE):
return resp.final_url
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
try:
yadis_loc = findHTMLMeta(StringIO(resp.body))
except MetaNotFound:
pass
return yadis_loc
def whereIsYadis(resp):
"""Given a HTTPResponse, return the location of the Yadis document.
May be the URL just retrieved, another URL, or None, if I can't
find any.
[non-blocking]
@returns: str or None
"""
# Attempt to find out where to go to discover the document
# or if we already have it
content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if content_type and content_type.split(';',
1)[0].lower() == YADIS_CONTENT_TYPE:
return resp.final_url
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
# Decode body by encoding of file
content_type = content_type or ''
encoding = content_type.rsplit(';', 1)
if len(encoding) == 2 and encoding[1].strip().startswith(
'charset='):
encoding = encoding[1].split('=', 1)[1].strip()
else:
encoding = 'UTF-8'
try:
content = resp.body.decode(encoding)
except UnicodeError:
# Keep encoded version in case yadis location can be found before encoding shut this up.
# Possible errors will be caught lower.
content = resp.body
try:
yadis_loc = findHTMLMeta(StringIO(content))
except (MetaNotFound, UnicodeError):
# UnicodeError: Response body could not be encoded and xrds location
# could not be found before troubles occurs.
pass
return yadis_loc
def whereIsYadis(resp):
"""Given a HTTPResponse, return the location of the Yadis document.
May be the URL just retrieved, another URL, or None, if I can't
find any.
[non-blocking]
@returns: str or None
"""
# Attempt to find out where to go to discover the document
# or if we already have it
content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if (content_type and
content_type.split(';', 1)[0].lower() == YADIS_CONTENT_TYPE):
return resp.final_url
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
# Decode body by encoding of file
content_type = content_type or ''
encoding = content_type.rsplit(';', 1)
if len(encoding) == 2 and encoding[1].strip().startswith('charset='):
encoding = encoding[1].split('=', 1)[1].strip()
else:
encoding = 'UTF-8'
try:
content = resp.body.decode(encoding)
except UnicodeError:
# Keep encoded version in case yadis location can be found before encoding shut this up.
# Possible errors will be caught lower.
content = resp.body
try:
yadis_loc = findHTMLMeta(StringIO(content))
except (MetaNotFound, UnicodeError):
# UnicodeError: Response body could not be encoded and xrds location
# could not be found before troubles occurs.
pass
return yadis_loc
def handle_starttag(self, tag, attrs):
# if we ever see a start body tag, bail out right away, since
# we want to prevent the meta tag from appearing in the body
# [2]
if tag == 'body':
self._terminate()
if self.phase == self.TOP:
# At the top level, allow a html tag or a head tag to move
# to the head or html phase
if tag == 'head':
# [3]
self.phase = self.HEAD
elif tag == 'html':
# [4]
self.phase = self.HTML
elif self.phase == self.HTML:
# if we are in the html tag, allow a head tag to move to
# the HEAD phase. If we get another html tag, then bail
# out
if tag == 'head':
# [3]
self.phase = self.HEAD
elif tag == 'html':
# [5]
self._terminate()
elif self.phase == self.HEAD:
# If we are in the head phase, look for the appropriate
# meta tag. If we get a head or body tag, bail out.
if tag == 'meta':
attrs_d = dict(attrs)
http_equiv = attrs_d.get('http-equiv', '').lower()
if http_equiv == YADIS_HEADER_NAME.lower():
raw_attr = attrs_d.get('content')
yadis_loc = substituteEntities(raw_attr)
# [6]
self.phase = self.FOUND
raise ParseDone(yadis_loc)
elif tag in ['head', 'html']:
# [5], [7]
self._terminate()
def handle_starttag(self, tag, attrs):
# if we ever see a start body tag, bail out right away, since
# we want to prevent the meta tag from appearing in the body
# [2]
if tag=='body':
self._terminate()
if self.phase == self.TOP:
# At the top level, allow a html tag or a head tag to move
# to the head or html phase
if tag == 'head':
# [3]
self.phase = self.HEAD
elif tag == 'html':
# [4]
self.phase = self.HTML
elif self.phase == self.HTML:
# if we are in the html tag, allow a head tag to move to
# the HEAD phase. If we get another html tag, then bail
# out
if tag == 'head':
# [3]
self.phase = self.HEAD
elif tag == 'html':
# [5]
self._terminate()
elif self.phase == self.HEAD:
# If we are in the head phase, look for the appropriate
# meta tag. If we get a head or body tag, bail out.
if tag == 'meta':
attrs_d = dict(attrs)
http_equiv = attrs_d.get('http-equiv', '').lower()
if http_equiv == YADIS_HEADER_NAME.lower():
raw_attr = attrs_d.get('content')
yadis_loc = substituteEntities(raw_attr)
# [6]
self.phase = self.FOUND
raise ParseDone(yadis_loc)
elif tag in ['head', 'html']:
# [5], [7]
self._terminate()
def findHTMLMeta(stream):
"""Look for a meta http-equiv tag with the YADIS header name.
@param stream: Source of the html text
@type stream: Readable text I/O file object
@return: The URI from which to fetch the XRDS document
@rtype: six.text_type
@raises MetaNotFound: raised with the content that was
searched as the first parameter.
"""
parser = etree.HTMLParser()
try:
html = etree.parse(stream, parser)
except (ValueError, etree.XMLSyntaxError):
raise MetaNotFound("Couldn't parse HTML page.")
# Invalid input may return element with no content
if html.getroot() is None:
raise MetaNotFound("Couldn't parse HTML page.")
# Create a XPath evaluator with a local function to lowercase values.
xpath_evaluator = etree.XPathEvaluator(html,
extensions={
(None, 'lower-case'):
xpath_lower_case
})
# Find YADIS meta tag, case insensitive to the header name.
yadis_headers = xpath_evaluator(
'/html/head/meta[lower-case(@http-equiv)="{}"]'.format(
YADIS_HEADER_NAME.lower()))
if not yadis_headers:
raise MetaNotFound('Yadis meta tag not found.')
yadis_header = yadis_headers[0]
yadis_url = yadis_header.get('content')
if yadis_url is None:
raise MetaNotFound('Attribute "content" missing in yadis meta tag.')
return yadis_url
def whereIsYadis(resp):
"""Given a HTTPResponse, return the location of the Yadis document.
May be the URL just retrieved, another URL, or None if no suitable URL can
be found.
[non-blocking]
@returns: str or None
"""
# Attempt to find out where to go to discover the document
# or if we already have it
content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if (content_type
and content_type.split(';', 1)[0].lower() == YADIS_CONTENT_TYPE):
return resp.final_url
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
# Decode body by encoding of file
content_type = content_type or ''
encoding = content_type.rsplit(';', 1)
if (len(encoding) == 2
and encoding[1].strip().startswith('charset=')):
encoding = encoding[1].split('=', 1)[1].strip()
else:
encoding = 'utf-8'
if isinstance(resp.body, bytes):
try:
content = resp.body.decode(encoding)
except UnicodeError:
# All right, the detected encoding has failed. Try with
# UTF-8 (even if there was no detected encoding and we've
# defaulted to UTF-8, it's not that expensive an operation)
try:
content = resp.body.decode('utf-8')
except UnicodeError:
# At this point the content cannot be decoded to a str
# using the detected encoding or falling back to utf-8,
# so we have to resort to replacing undecodable chars.
# This *will* result in broken content but there isn't
# anything else that can be done.
content = resp.body.decode(encoding, 'replace')
else:
content = resp.body
try:
yadis_loc = findHTMLMeta(StringIO(content))
except (MetaNotFound, UnicodeError):
# UnicodeError: Response body could not be encoded and xrds
# location could not be found before troubles occur.
pass
return yadis_loc
def whereIsYadis(resp):
"""Given a HTTPResponse, return the location of the Yadis document.
May be the URL just retrieved, another URL, or None if no suitable URL can
be found.
[non-blocking]
@returns: str or None
"""
# Attempt to find out where to go to discover the document
# or if we already have it
content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if (content_type and
content_type.split(';', 1)[0].lower() == YADIS_CONTENT_TYPE):
return resp.final_url
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
# Decode body by encoding of file
content_type = content_type or ''
encoding = content_type.rsplit(';', 1)
if (len(encoding) == 2 and
encoding[1].strip().startswith('charset=')):
encoding = encoding[1].split('=', 1)[1].strip()
else:
encoding = 'utf-8'
if isinstance(resp.body, bytes):
try:
content = resp.body.decode(encoding)
except UnicodeError:
# All right, the detected encoding has failed. Try with
# UTF-8 (even if there was no detected encoding and we've
# defaulted to UTF-8, it's not that expensive an operation)
try:
content = resp.body.decode('utf-8')
except UnicodeError:
# At this point the content cannot be decoded to a str
# using the detected encoding or falling back to utf-8,
# so we have to resort to replacing undecodable chars.
# This *will* result in broken content but there isn't
# anything else that can be done.
content = resp.body.decode(encoding, 'replace')
else:
content = resp.body
try:
yadis_loc = findHTMLMeta(StringIO(content))
except (MetaNotFound, UnicodeError):
# UnicodeError: Response body could not be encoded and xrds
# location could not be found before troubles occur.
pass
return yadis_loc
def findHTMLMeta(stream):
"""Look for a meta http-equiv tag with the YADIS header name.
@param stream: Source of the html text
@type stream: Readable text I/O file object
@return: The URI from which to fetch the XRDS document
@rtype: six.text_type
@raises MetaNotFound: raised with the content that was
searched as the first parameter.
"""
parser = etree.HTMLParser()
try:
html = etree.parse(stream, parser)
except (ValueError, etree.XMLSyntaxError):
raise MetaNotFound("Couldn't parse HTML page.")
# Invalid input may return element with no content
if html.getroot() is None:
raise MetaNotFound("Couldn't parse HTML page.")
# Create a XPath evaluator with a local function to lowercase values.
xpath_evaluator = etree.XPathEvaluator(html, extensions={(None, 'lower-case'): xpath_lower_case})
# Find YADIS meta tag, case insensitive to the header name.
yadis_headers = xpath_evaluator('/html/head/meta[lower-case(@http-equiv)="{}"]'.format(YADIS_HEADER_NAME.lower()))
if not yadis_headers:
raise MetaNotFound('Yadis meta tag not found.')
yadis_header = yadis_headers[0]
yadis_url = yadis_header.get('content')
if yadis_url is None:
raise MetaNotFound('Attribute "content" missing in yadis meta tag.')
return yadis_url
def discover(uri):
"""Discover services for a given URI.
@param uri: The identity URI as a well-formed http or https
URI. The well-formedness and the protocol are not checked, but
the results of this function are undefined if those properties
do not hold.
@return: DiscoveryResult object
@raises Exception: Any exception that can be raised by fetching a URL with
the given fetcher.
"""
result = DiscoveryResult(uri)
resp = fetchers.fetch(uri, headers={'Accept': YADIS_ACCEPT_HEADER})
if resp.status != 200:
raise DiscoveryFailure(
'HTTP Response status from identity URL host is not 200. '
'Got status %r' % (resp.status,), resp)
# Note the URL after following redirects
result.normalized_uri = resp.final_url
# Attempt to find out where to go to discover the document
# or if we already have it
result.content_type = resp.headers.get('content-type')
# According to the spec, the content-type header must be an exact
# match, or else we have to look for an indirection.
if (result.content_type and
result.content_type.split(';', 1)[0].lower() == YADIS_CONTENT_TYPE):
result.xrds_uri = result.normalized_uri
else:
# Try the header
yadis_loc = resp.headers.get(YADIS_HEADER_NAME.lower())
if not yadis_loc:
# Parse as HTML if the header is missing.
#
# XXX: do we want to do something with content-type, like
# have a whitelist or a blacklist (for detecting that it's
# HTML)?
try:
yadis_loc = findHTMLMeta(StringIO(resp.body))
except MetaNotFound:
pass
# At this point, we have not found a YADIS Location URL. We
# will return the content that we scanned so that the caller
# can try to treat it as an XRDS if it wishes.
if yadis_loc:
result.xrds_uri = yadis_loc
resp = fetchers.fetch(yadis_loc)
if resp.status != 200:
exc = DiscoveryFailure(
'HTTP Response status from Yadis host is not 200. '
'Got status %r' % (resp.status,), resp)
exc.identity_url = result.normalized_uri
raise exc
result.content_type = resp.headers.get('content-type')
result.response_text = resp.body
return result
