#------------------------------------------------------------------------------
#
# Copyright (c) Microsoft Corporation.
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# This code is licensed under the MIT License.
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# of this software and associated documentation files(the "Software"), to deal
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# The above copyright notice and this permission notice shall be included in
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
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#------------------------------------------------------------------------------
try:
from xml.etree import cElementTree as ET
except ImportError:
from xml.etree import ElementTree as ET
import re
from . import xmlutil
from . import log
from .adal_error import AdalError
from .constants import WSTrustVersion
# Creates a log message that contains the RSTR scrubbed of the actual SAML assertion.
def scrub_rstr_log_message(response_str):
# A regular expression for finding the SAML Assertion in an response_str. Used to remove the SAML
# assertion when logging the response_str.
assertion_regex = r'RequestedSecurityToken.*?((<.*?:Assertion.*?>).*<\/.*?Assertion>).*?'
single_line_rstr, _ = re.subn(r'(\r\n|\n|\r)', '', response_str)
match = re.search(assertion_regex, single_line_rstr)
if not match:
#No Assertion was matched so just return the response_str as is.
scrubbed_rstr = single_line_rstr
else:
saml_assertion = match.group(1)
saml_assertion_start_tag = match.group(2)
scrubbed_rstr = single_line_rstr.replace(
saml_assertion, saml_assertion_start_tag + 'ASSERTION CONTENTS REDACTED')
return 'RSTR Response: ' + scrubbed_rstr
def findall_content(xml_string, tag):
"""
Given a tag name without any prefix,
this function returns a list of the raw content inside this tag as-is.
>>> findall_content(" what ever content ", "foo")
[" what ever content "]
Motivation:
Usually we would use XML parser to extract the data by xpath.
However the ElementTree in Python will implicitly normalize the output
by "hoisting" the inner inline namespaces into the outmost element.
The result will be a semantically equivalent XML snippet,
but not fully identical to the original one.
While this effect shouldn't become a problem in all other cases,
it does not seem to fully comply with Exclusive XML Canonicalization spec
(https://www.w3.org/TR/xml-exc-c14n/), and void the SAML token signature.
SAML signature algo needs the "XML -> C14N(XML) -> Signed(C14N(Xml))" order.
The binary extention lxml is probably the canonical way to solve this
(https://stackoverflow.com/questions/22959577/python-exclusive-xml-canonicalization-xml-exc-c14n)
but here we use this workaround, based on Regex, to return raw content as-is.
"""
# \w+ is good enough for https://www.w3.org/TR/REC-xml/#NT-NameChar
pattern = r"<(?:\w+:)?%(tag)s(?:[^>]*)>(.*)(?:\w+:)?%(tag)s" % {"tag": tag}
return re.findall(pattern, xml_string, re.DOTALL)
class WSTrustResponse(object):
def __init__(self, call_context, response, wstrust_version):
self._log = log.Logger("WSTrustResponse", call_context['log_context'])
self._call_context = call_context
self._response = response
self._dom = None
self._parents = None
self.error_code = None
self.fault_message = None
self.token_type = None
self.token = None
self._wstrust_version = wstrust_version
if response:
self._log.debug(scrub_rstr_log_message(response))
# Sample error message
#
#
# http://www.w3.org/2005/08/addressing/soap/fault
# -
#
# 2013-07-30T00:32:21.989Z
# 2013-07-30T00:37:21.989Z
#
#
#
#
#
#
# s:Sender
#
# a:RequestFailed
#
#
#
# MSIS3127: The specified request failed.
#
#
#
#
def _parse_error(self):
error_found = False
fault_node = xmlutil.xpath_find(self._dom, 's:Body/s:Fault/s:Reason/s:Text')
if fault_node:
self.fault_message = fault_node[0].text
if self.fault_message:
error_found = True
# Subcode has minoccurs=0 and maxoccurs=1(default) according to the http://www.w3.org/2003/05/soap-envelope
# Subcode may have another subcode as well. This is only targetting at top level subcode.
# Subcode value may have different messages not always uses http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd.
# text inside the value is not possible to select without prefix, so substring is necessary
subnode = xmlutil.xpath_find(self._dom, 's:Body/s:Fault/s:Code/s:Subcode/s:Value')
if len(subnode) > 1:
raise AdalError("Found too many fault code values: {}".format(len(subnode)))
if subnode:
error_code = subnode[0].text
self.error_code = error_code.split(':')[1]
return error_found
def _parse_token(self):
if self._wstrust_version == WSTrustVersion.WSTRUST2005:
token_type_nodes_xpath = 's:Body/t:RequestSecurityTokenResponse/t:TokenType'
security_token_xpath = 't:RequestedSecurityToken'
else:
token_type_nodes_xpath = 's:Body/wst:RequestSecurityTokenResponseCollection/wst:RequestSecurityTokenResponse/wst:TokenType'
security_token_xpath = 'wst:RequestedSecurityToken'
token_type_nodes = xmlutil.xpath_find(self._dom, token_type_nodes_xpath)
if not token_type_nodes:
raise AdalError("No TokenType nodes found in RSTR")
for node in token_type_nodes:
if self.token:
self._log.warn("Found more than one returned token. Using the first.")
break
token_type = xmlutil.find_element_text(node)
if not token_type:
self._log.warn("Could not find token type in RSTR token.")
requested_token_node = xmlutil.xpath_find(self._parents[node], security_token_xpath)
if len(requested_token_node) > 1:
raise AdalError("Found too many RequestedSecurityToken nodes for token type: {}".format(token_type))
if not requested_token_node:
self._log.warn(
"Unable to find RequestsSecurityToken element associated with TokenType element: %(token_type)s",
{"token_type": token_type})
continue
# Adjust namespaces (without this they are autogenerated) so this is understood
# by the receiver. Then make a string repr of the element tree node.
# See also http://blog.tomhennigan.co.uk/post/46945128556/elementtree-and-xmlns
ET.register_namespace('saml', 'urn:oasis:names:tc:SAML:1.0:assertion')
ET.register_namespace('ds', 'http://www.w3.org/2000/09/xmldsig#')
token = ET.tostring(requested_token_node[0][0])
if token is None:
self._log.warn(
"Unable to find token associated with TokenType element: %(token_type)s",
{"token_type": token_type})
continue
self.token = token
self.token_type = token_type
self._log.info(
"Found token of type: %(token_type)s",
{"token_type": self.token_type})
if self.token is None:
raise AdalError("Unable to find any tokens in RSTR.")
@staticmethod
def _parse_token_by_re(raw_response):
for rstr in findall_content(raw_response, "RequestSecurityTokenResponse"):
token_types = findall_content(rstr, "TokenType")
tokens = findall_content(rstr, "RequestedSecurityToken")
if token_types and tokens:
return tokens[0].encode('us-ascii'), token_types[0]
def parse(self):
if not self._response:
raise AdalError("Received empty RSTR response body.")
try:
self._dom = ET.fromstring(self._response)
except Exception as exp:
raise AdalError('Failed to parse RSTR in to DOM', exp)
try:
self._parents = {c:p for p in self._dom.iter() for c in p}
error_found = self._parse_error()
if error_found:
str_error_code = self.error_code or 'NONE'
str_fault_message = self.fault_message or 'NONE'
error_template = 'Server returned error in RSTR - ErrorCode: {} : FaultMessage: {}'
raise AdalError(error_template.format(str_error_code, str_fault_message))
token_found = self._parse_token_by_re(self._response)
if token_found:
self.token, self.token_type = token_found
else: # fallback to old logic
self._parse_token()
finally:
self._dom = None
self._parents = None