✨ [#403] Fetch IDP metadata using requests

Using requests allows us to easily customize the CA_BUNDLE to use
when verifying the server certificate, instead of having to disable SSL
certificate verification alltogether.

Author: sergei-maertens

pyproject.toml

@@ -35,6 +35,7 @@ dependencies = [
     "lxml>=4.6.5,!=4.7.0",
     "xmlsec>=1.3.9",
     "isodate>=0.6.1",
+    "requests",
 ]
 requires-python = ">=3.7"
 
@@ -119,4 +120,4 @@ ignore_errors = true
 
 
 [tool.coverage.html]
-directory = "coverage_html_report"
+directory = "coverage_html_report"

src/onelogin/saml2/idp_metadata_parser.py

@@ -7,10 +7,7 @@
 
 from copy import deepcopy
 
-try:
-    import urllib.request as urllib2
-except ImportError:
-    import urllib2
+import requests
 
 import ssl
 
@@ -30,6 +27,13 @@ class OneLogin_Saml2_IdPMetadataParser(object):
     def get_metadata(cls, url, validate_cert=True, timeout=None, headers=None):
         """
         Gets the metadata XML from the provided URL
+
+        The metadata is retrieved with the ``requests`` library. If you need to support
+        server certificates that are not readily available in the trust store, use the
+        ``REQUESTS_CA_BUNDLE`` environment variable. See the
+        `advanced documentation <https://requests.readthedocs.io/en/latest/user/advanced/>`_
+        for more information.
+
         :param url: Url where the XML of the Identity Provider Metadata is published.
         :type url: string
 
@@ -46,16 +50,9 @@ def get_metadata(cls, url, validate_cert=True, timeout=None, headers=None):
         """
         valid = False
 
-        request = urllib2.Request(url, headers=headers or {})
-
-        if validate_cert:
-            response = urllib2.urlopen(request, timeout=timeout)
-        else:
-            ctx = ssl.create_default_context()
-            ctx.check_hostname = False
-            ctx.verify_mode = ssl.CERT_NONE
-            response = urllib2.urlopen(request, context=ctx, timeout=timeout)
-        xml = response.read()
+        response = requests.get(url, headers=headers, verify=validate_cert, timeout=timeout)
+        response.raise_for_status()
+        xml = response.content
 
         if xml:
             try:

tests/src/OneLogin/saml2_tests/idp_metadata_parser_test.py

@@ -1,15 +1,10 @@
 # -*- coding: utf-8 -*-
 
-
-try:
-    from urllib.error import URLError
-except ImportError:
-    from urllib2 import URLError
-
 from copy import deepcopy
 import json
 from os.path import dirname, join, exists
 from lxml.etree import XMLSyntaxError
+from requests import RequestException
 import unittest
 
 from onelogin.saml2.idp_metadata_parser import OneLogin_Saml2_IdPMetadataParser
@@ -51,7 +46,7 @@ def testGetMetadata(self):
         try:
             data = OneLogin_Saml2_IdPMetadataParser.get_metadata("https://raw.githubusercontent.com/SAML-Toolkits/python3-saml/master/tests/data/metadata/testshib-providers.xml", validate_cert=False)
             self.assertTrue(data is not None and data is not {})
-        except URLError:
+        except RequestException:
             pass
 
     def testGetMetadataWithHeaders(self):
@@ -70,7 +65,7 @@ def testParseRemote(self):
 
         try:
             data = OneLogin_Saml2_IdPMetadataParser.parse_remote("https://raw.githubusercontent.com/SAML-Toolkits/python3-saml/master/tests/data/metadata/testshib-providers.xml", validate_cert=False)
-        except URLError:
+        except RequestException:
             xml = self.file_contents(join(self.data_path, "metadata", "testshib-providers.xml"))
             data = OneLogin_Saml2_IdPMetadataParser.parse(xml)
 
@@ -162,7 +157,7 @@ def test_parse_testshib_required_binding_sso_redirect(self):
         """
         try:
             xmldoc = OneLogin_Saml2_IdPMetadataParser.get_metadata("https://idp.testshib.org/idp/shibboleth")
-        except URLError:
+        except RequestException:
             xmldoc = self.file_contents(join(self.data_path, "metadata", "testshib-providers.xml"))
 
         # Parse, require SSO REDIRECT binding, implicitly.
@@ -196,7 +191,7 @@ def test_parse_testshib_required_binding_sso_post(self):
         """
         try:
             xmldoc = OneLogin_Saml2_IdPMetadataParser.get_metadata("https://idp.testshib.org/idp/shibboleth")
-        except URLError:
+        except RequestException:
             xmldoc = self.file_contents(join(self.data_path, "metadata", "testshib-providers.xml"))
 
         # Parse, require POST binding.