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uri.py
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uri.py
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"""XCAP URI module
http://tools.ietf.org/html/rfc4825#section-6
"""
import re
from urllib import unquote
from copy import copy
from xml.sax.saxutils import quoteattr
from lxml import _elementpath as ElementPath
from application.configuration import *
from application import log
from xcap.errors import *
XPATH_DEFAULT_PREFIX = 'default' # should be more random
class XCAPUser(object):
"""XCAP ID."""
def __init__(self, username, domain):
self.username = username
self.domain = domain
@property
def uri(self):
return 'sip:%s@%s' % (self.username, self.domain)
def __eq__(self, other):
return isinstance(other, XCAPUser) and self.uri == other.uri
def __ne__(self, other):
return not self.__eq__(other)
def __nonzero__(self):
return bool(self.username) and bool(self.domain)
def __str__(self):
return "%s@%s" % (self.username, self.domain)
def __repr__(self):
return 'XCAPUser(%r, %r)' % (self.username, self.domain)
@classmethod
def parse(cls, user_id, default_domain=None):
if user_id.startswith("sip:"):
user_id = user_id[4:]
_split = user_id.split('@', 1)
username = _split[0]
if len(_split) == 2:
domain = _split[1]
else:
domain = default_domain
return cls(username, domain)
# XXX currently equivalent but differently encoded URIs won't be considered equal.
def unquote_attr_value(s):
if len(s)>1 and s[0]==s[-1] and s[0] in '"\'':
# what about " and friends?
return s[1:-1]
raise NodeParsingError
def xpath_tokenizer(p):
out = []
prev = None
for op, tag in ElementPath.xpath_tokenizer(p):
if prev == '=':
unq = unquote_attr_value
else:
unq = unquote
if op:
x = Op(unq(op))
else:
x = Tag(unq(tag))
out.append(x)
prev = x
return out
class Op(str):
tag = False
class Tag(str):
tag = True
class TerminalSelector(object):
pass
class AttributeSelector(TerminalSelector):
def __init__(self, attribute):
self.attribute = attribute
def __str__(self):
return '@' + self.attribute
def __repr__(self):
return 'AttributeSelector(%r)' % self.attribute
class NamespaceSelector(TerminalSelector):
def __str__(self):
return "namespace::*"
def __repr__(self):
return 'NamespaceSelector()'
class Str(str):
def __repr__(self):
return '%s(%s)' % (self.__class__.__name__, str.__repr__(self))
class NodeParsingError(ValueError):
pass
def parse_qname(qname, defnamespace, namespaces):
if qname == '*':
return qname
try:
prefix, name = qname.split(':')
except ValueError:
return (defnamespace, qname)
else:
return (namespaces[prefix], name)
class Step(object):
def __init__(self, name, position=None, att_name=None, att_value=None):
self.name = name
self.position = position
self.att_name = att_name
self.att_value = att_value
def __repr__(self):
args = [self.name, self.position, self.att_name, self.att_value]
while args and args[-1] is None:
del args[-1]
args = [repr(x) for x in args]
return 'Step(%s)' % ', '.join(args)
def step2str(step, namespace2prefix = {}):
try:
namespace, name = step.name
except ValueError:
res = step.name
else:
prefix = namespace2prefix[namespace]
if prefix:
res = prefix + ':' + name
else:
res = name
if step.position is not None:
res += '[%s]' % step.position
if step.att_name is not None:
namespace, name = step.att_name
if namespace:
prefix = namespace2prefix[namespace]
else:
prefix = None
if prefix:
res += '[@%s:%s=%s]' % (prefix, name, quoteattr(step.att_value))
else:
res += '[@%s=%s]' % (name, quoteattr(step.att_value))
return res
def read_element_tag(lst, index, namespace, namespaces):
if index==len(lst):
raise NodeParsingError
elif lst[index] == '*':
return '*', index+1
elif get(lst, index+1)==':':
if not lst[index].tag:
raise NodeParsingError
if not get(lst, index+2) or not get(lst, index+2).tag:
raise NodeParsingError
return (namespaces[lst[index]], lst[index+2]), index+3
else:
return (namespace, lst[index]), index+1
def read_position(lst, index):
if get(lst, index)=='[' and get(lst, index+2)==']':
return int(lst[index+1]), index+3
return None, index
# XML attributes don't belong to the same namespace as containing tag?
# because thats what I get in startElement/attrs.items - (None, 'tag')
# lxml's xpath works similar way too:
# doc.xpath('/default:rls-services/defaultg:service[@uri="sip:mybuddies@example.com"]',
# namespaces = {'default':"urn:ietf:params:xml:ns:rls-services"})
# works, while
# doc.xpath('/default:rls-services/defaultg:service[@default:uri="sip:mybuddies@example.com"]',
# namespaces = {'default':"urn:ietf:params:xml:ns:rls-services"})
# does not
# that's why _namespace parameter is ignored and None is supplied in that case
def read_att_test(lst, index, _namespace, namespaces):
if get(lst, index)=='[' and get(lst, index+1)=='@' and get(lst, index+3)=='=' and get(lst, index+5)==']':
return (None, lst[index+2]), lst[index+4], index+6
elif get(lst, index)=='[' and get(lst, index+1)=='@' and get(lst, index+3)==':' \
and get(lst, index+5)=='=' and get(lst, index+7)==']':
return (namespaces[lst[index+2]], lst[index+4]), lst[index+6], index+8
return None, None, index
def get(lst, index, default=None):
try:
return lst[index]
except LookupError:
return default
def read_step(lst, index, namespace, namespaces):
if get(lst, index)=='@':
return AttributeSelector(lst[index+1]), index+2
elif get(lst, index)=='namespace' and get(lst, index+1)=='::' and get(lst, index+2)=='*':
return NamespaceSelector(), index+3
else:
tag, index = read_element_tag(lst, index, namespace, namespaces)
position, index = read_position(lst, index)
att_name, att_value, index = read_att_test(lst, index, namespace, namespaces)
return Step(tag, position, att_name, att_value), index
def read_slash(lst, index):
if get(lst, index)=='/':
return index+1
raise NodeParsingError
def read_node_selector(lst, namespace, namespaces):
index = 0
if get(lst, 0)=='/':
index = read_slash(lst, index)
steps = []
terminal_selector = None
while True:
step, index = read_step(lst, index, namespace, namespaces)
if isinstance(step, TerminalSelector):
if index != len(lst):
raise NodeParsingError
terminal_selector = step
break
steps.append(step)
if index == len(lst):
break
index = read_slash(lst, index)
return ElementSelector(steps, namespace, namespaces), terminal_selector
def parse_node_selector(s, namespace=None, namespaces=None):
"""
>>> parse_node_selector('/resource-lists', None, {})
([Step((None, 'resource-lists'))], None)
>>> parse_node_selector('/resource-lists/list[1]/entry[@uri="sip:bob@example.com"]', None, {})
([Step((None, 'resource-lists')), Step((None, 'list'), 1), Step((None, 'entry'), None, (None, 'uri'), 'sip:bob@example.com')], None)
>>> parse_node_selector('/*/list[1][@name="friends"]/@name')
([Step('*'), Step((None, 'list'), 1, (None, 'name'), 'friends')], AttributeSelector('name'))
>>> parse_node_selector('/*[10][@att="val"]/namespace::*')
([Step('*', 10, (None, 'att'), 'val')], NamespaceSelector())
>>> x = parse_node_selector('/resource-lists/list[@name="friends"]/external[@anchor="http://xcap.example.org/resource-lists/users/sip:a@example.org/index/~~/resource-lists/list%5b@name=%22mkting%22%5d"]')
"""
if namespaces is None:
namespaces = {}
tokens = xpath_tokenizer(s)
try:
return read_node_selector(tokens, namespace, namespaces)
except NodeParsingError, ex:
ex.args = (repr(s),)
raise
except:
log.error('internal error in parse_node_selector(%r)' % s)
raise
class ElementSelector(list):
def __init__(self, lst, namespace, namespaces):
list.__init__(self, lst)
self.namespace = namespace
self.namespaces = namespaces
def replace_default_prefix(self, namespace2prefix):
"fix string representation so it'll work with lxml xpath"
steps = []
for step in self:
try:
namespace, name = step.name
except ValueError:
steps.append(str(step))
else:
steps.append(step2str(step, namespace2prefix))
return '/' + '/'.join(steps)
xml_tag = re.compile('\s*<([^ >/]+)')
def fix_star(self, element_body):
"""
>>> elem_selector = parse_node_selector('/watcherinfo/watcher-list/*[@id="8ajksjda7s"]', None, {})[0]
>>> elem_selector.fix_star('<watcher/>')[-1].name[1]
'watcher'
"""
if self and self[-1].name == '*' and self[-1].position is None:
m = self.xml_tag.match(element_body)
if m:
(name, ) = m.groups()
result = copy(self)
result[-1].name = parse_qname(name, self.namespace, self.namespaces)
return result
return self
class NodeSelector(object):
XMLNS_REGEXP = re.compile("xmlns\((?P<nsdata>.*?)\)")
def __init__(self, selector, namespace=None):
sections = selector.split('?', 1)
if len(sections) == 2: ## a query component is present
self.ns_bindings = self._parse_query(sections[1])
else:
self.ns_bindings = {}
self.element_selector, self.terminal_selector = parse_node_selector(selector, namespace, self.ns_bindings)
## http://www.w3.org/TR/2003/REC-xptr-xmlns-20030325/
def _parse_query(self, query):
"""Return a dictionary of namespace bindings defined by the xmlns() XPointer
expressions from the given query."""
ns_bindings = {}
ns_matches = self.XMLNS_REGEXP.findall(query)
for m in ns_matches:
try:
prefix, ns = m.split('=')
ns_bindings[prefix] = ns
except ValueError:
log.error("Ignoring invalid XPointer XMLNS expression: %s" % m)
continue
return ns_bindings
def replace_default_prefix(self, defprefix=XPATH_DEFAULT_PREFIX, append_terminal = True):
namespace2prefix = dict((v, k) for (k, v) in self.ns_bindings)
namespace2prefix[self.element_selector.namespace] = defprefix
res = self.element_selector.replace_default_prefix(namespace2prefix)
if append_terminal and self.terminal_selector:
res += '/' + str(self.terminal_selector)
return res
def get_ns_bindings(self, default_ns):
ns_bindings = self.ns_bindings.copy()
ns_bindings[XPATH_DEFAULT_PREFIX] = default_ns
return ns_bindings
class DocumentSelector(Str):
"""Constructs a DocumentSelector containing the application_id, context, user_id
and document from the given selector string.
>>> x = DocumentSelector('/resource-lists/users/sip:joe@example.com/index')
>>> x.application_id, x.context, x.user_id, x.document_path
('resource-lists', 'users', 'sip:joe@example.com', 'index')
>>> x = DocumentSelector('/rls-services/global/index')
>>> x.application_id, x.context, x.user_id, x.document_path
('rls-services', 'global', None, 'index')
"""
def __init__(self, selector):
if not isinstance(selector, str):
raise TypeError("Document Selector must be a string")
segments = selector.split('/')
if not segments[0]: ## ignore first '/'
segments.pop(0)
if not segments[-1]: ## ignore last '/' if present
segments.pop()
if len(segments) < 2:
raise ValueError("invalid Document Selector")
self.application_id = segments[0]
self.context = segments[1] ## either "global" or "users"
if self.context not in ("users", "global"):
raise ValueError("the Document Selector context must be 'users' or 'global': '%s'" % self.context)
self.user_id = None
if self.context == "users":
self.user_id = segments[2]
segments = segments[3:]
else:
segments = segments[2:]
if not segments:
raise ValueError("invalid Document Selector: missing document's path")
self.document_path = '/'.join(segments)
class XCAPUri(object):
"""An XCAP URI containing the XCAP root, document selector and node selector."""
node_selector_separator = "~~"
def __init__(self, xcap_root, resource_selector, namespaces):
"namespaces maps application id to default namespace"
self.xcap_root = xcap_root
self.resource_selector = resource_selector
realm = None
# convention to get the realm if it's not contained in the user ID section
# of the document selector (bad eyebeam)
if self.resource_selector.startswith("@"):
first_slash = self.resource_selector.find("/")
realm = self.resource_selector[1:first_slash]
self.resource_selector = self.resource_selector[first_slash:]
_split = self.resource_selector.split(self.node_selector_separator, 1)
doc_selector = _split[0]
try:
self.doc_selector = DocumentSelector(doc_selector) ## the Document Selector
except (TypeError, ValueError), e:
log.error("Invalid Document Selector %s (%s)" % (doc_selector, str(e)))
raise ResourceNotFound(str(e))
self.application_id = self.doc_selector.application_id
if len(_split) == 2: ## the Node Selector
self.node_selector = NodeSelector(_split[1], namespaces.get(self.application_id))
else:
self.node_selector = None
if self.doc_selector.user_id:
self.user = XCAPUser.parse(self.doc_selector.user_id, realm)
else:
self.user = XCAPUser(None, realm)
def __str__(self):
return self.xcap_root + self.resource_selector
if __name__=='__main__':
import doctest
doctest.testmod()

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