/usr/lib/python2.7/dist-packages/openid/yadis/parsehtml.py is in python-openid 2.2.5-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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from HTMLParser import HTMLParser, HTMLParseError
import htmlentitydefs
import re
from openid.yadis.constants import YADIS_HEADER_NAME
# Size of the chunks to search at a time (also the amount that gets
# read at a time)
CHUNK_SIZE = 1024 * 16 # 16 KB
class ParseDone(Exception):
"""Exception to hold the URI that was located when the parse is
finished. If the parse finishes without finding the URI, set it to
None."""
class MetaNotFound(Exception):
"""Exception to hold the content of the page if we did not find
the appropriate <meta> tag"""
re_flags = re.IGNORECASE | re.UNICODE | re.VERBOSE
ent_pat = r'''
&
(?: \#x (?P<hex> [a-f0-9]+ )
| \# (?P<dec> \d+ )
| (?P<word> \w+ )
)
;'''
ent_re = re.compile(ent_pat, re_flags)
def substituteMO(mo):
if mo.lastgroup == 'hex':
codepoint = int(mo.group('hex'), 16)
elif mo.lastgroup == 'dec':
codepoint = int(mo.group('dec'))
else:
assert mo.lastgroup == 'word'
codepoint = htmlentitydefs.name2codepoint.get(mo.group('word'))
if codepoint is None:
return mo.group()
else:
return unichr(codepoint)
def substituteEntities(s):
return ent_re.sub(substituteMO, s)
class YadisHTMLParser(HTMLParser):
"""Parser that finds a meta http-equiv tag in the head of a html
document.
When feeding in data, if the tag is matched or it will never be
found, the parser will raise ParseDone with the uri as the first
attribute.
Parsing state diagram
=====================
Any unlisted input does not affect the state::
1, 2, 5 8
+--------------------------+ +-+
| | | |
4 | 3 1, 2, 5, 7 v | v
TOP -> HTML -> HEAD ----------> TERMINATED
| | ^ | ^ ^
| | 3 | | | |
| +------------+ +-> FOUND ------+ |
| 6 8 |
| 1, 2 |
+------------------------------------+
1. any of </body>, </html>, </head> -> TERMINATE
2. <body> -> TERMINATE
3. <head> -> HEAD
4. <html> -> HTML
5. <html> -> TERMINATE
6. <meta http-equiv='X-XRDS-Location'> -> FOUND
7. <head> -> TERMINATE
8. Any input -> TERMINATE
"""
TOP = 0
HTML = 1
HEAD = 2
FOUND = 3
TERMINATED = 4
def __init__(self):
HTMLParser.__init__(self)
self.phase = self.TOP
def _terminate(self):
self.phase = self.TERMINATED
raise ParseDone(None)
def handle_endtag(self, tag):
# If we ever see an end of head, body, or html, bail out right away.
# [1]
if tag in ['head', 'body', 'html']:
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 feed(self, chars):
# [8]
if self.phase in [self.TERMINATED, self.FOUND]:
self._terminate()
return HTMLParser.feed(self, chars)
def findHTMLMeta(stream):
"""Look for a meta http-equiv tag with the YADIS header name.
@param stream: Source of the html text
@type stream: Object that implements a read() method that works
like file.read
@return: The URI from which to fetch the XRDS document
@rtype: str
@raises MetaNotFound: raised with the content that was
searched as the first parameter.
"""
parser = YadisHTMLParser()
chunks = []
while 1:
chunk = stream.read(CHUNK_SIZE)
if not chunk:
# End of file
break
chunks.append(chunk)
try:
parser.feed(chunk)
except HTMLParseError, why:
# HTML parse error, so bail
chunks.append(stream.read())
break
except ParseDone, why:
uri = why[0]
if uri is None:
# Parse finished, but we may need the rest of the file
chunks.append(stream.read())
break
else:
return uri
content = ''.join(chunks)
raise MetaNotFound(content)
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