Update request urllib3 (#464)

* requests: updated to version 2.27.1

* urllib3: updated to version 1.26.18

lib/urllib3/contrib/_appengine_environ.py

@@ -6,27 +6,31 @@ import os
 
 
 def is_appengine():
-    return is_local_appengine() or is_prod_appengine() or is_prod_appengine_mvms()
+    return is_local_appengine() or is_prod_appengine()
 
 
 def is_appengine_sandbox():
-    return is_appengine() and not is_prod_appengine_mvms()
+    """Reports if the app is running in the first generation sandbox.
+
+    The second generation runtimes are technically still in a sandbox, but it
+    is much less restrictive, so generally you shouldn't need to check for it.
+    see https://cloud.google.com/appengine/docs/standard/runtimes
+    """
+    return is_appengine() and os.environ["APPENGINE_RUNTIME"] == "python27"
 
 
 def is_local_appengine():
-    return (
-        "APPENGINE_RUNTIME" in os.environ
-        and "Development/" in os.environ["SERVER_SOFTWARE"]
-    )
+    return "APPENGINE_RUNTIME" in os.environ and os.environ.get(
+        "SERVER_SOFTWARE", ""
+    ).startswith("Development/")
 
 
 def is_prod_appengine():
-    return (
-        "APPENGINE_RUNTIME" in os.environ
-        and "Google App Engine/" in os.environ["SERVER_SOFTWARE"]
-        and not is_prod_appengine_mvms()
-    )
+    return "APPENGINE_RUNTIME" in os.environ and os.environ.get(
+        "SERVER_SOFTWARE", ""
+    ).startswith("Google App Engine/")
 
 
 def is_prod_appengine_mvms():
-    return os.environ.get("GAE_VM", False) == "true"
+    """Deprecated."""
+    return False

lib/urllib3/contrib/_securetransport/bindings.py

@@ -32,30 +32,26 @@ license and by oscrypto's:
 from __future__ import absolute_import
 
 import platform
-from ctypes.util import find_library
 from ctypes import (
-    c_void_p,
-    c_int32,
-    c_char_p,
-    c_size_t,
+    CDLL,
+    CFUNCTYPE,
+    POINTER,
+    c_bool,
     c_byte,
+    c_char_p,
+    c_int32,
+    c_long,
+    c_size_t,
     c_uint32,
     c_ulong,
-    c_long,
-    c_bool,
+    c_void_p,
 )
-from ctypes import CDLL, POINTER, CFUNCTYPE
+from ctypes.util import find_library
 
+from ...packages.six import raise_from
 
-security_path = find_library("Security")
-if not security_path:
-    raise ImportError("The library Security could not be found")
-
-
-core_foundation_path = find_library("CoreFoundation")
-if not core_foundation_path:
-    raise ImportError("The library CoreFoundation could not be found")
-
+if platform.system() != "Darwin":
+    raise ImportError("Only macOS is supported")
 
 version = platform.mac_ver()[0]
 version_info = tuple(map(int, version.split(".")))
@@ -65,8 +61,31 @@ if version_info < (10, 8):
         % (version_info[0], version_info[1])
     )
 
-Security = CDLL(security_path, use_errno=True)
-CoreFoundation = CDLL(core_foundation_path, use_errno=True)
+
+def load_cdll(name, macos10_16_path):
+    """Loads a CDLL by name, falling back to known path on 10.16+"""
+    try:
+        # Big Sur is technically 11 but we use 10.16 due to the Big Sur
+        # beta being labeled as 10.16.
+        if version_info >= (10, 16):
+            path = macos10_16_path
+        else:
+            path = find_library(name)
+        if not path:
+            raise OSError  # Caught and reraised as 'ImportError'
+        return CDLL(path, use_errno=True)
+    except OSError:
+        raise_from(ImportError("The library %s failed to load" % name), None)
+
+
+Security = load_cdll(
+    "Security", "/System/Library/Frameworks/Security.framework/Security"
+)
+CoreFoundation = load_cdll(
+    "CoreFoundation",
+    "/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation",
+)
+
 
 Boolean = c_bool
 CFIndex = c_long
@@ -276,6 +295,13 @@ try:
     Security.SSLSetProtocolVersionMax.argtypes = [SSLContextRef, SSLProtocol]
     Security.SSLSetProtocolVersionMax.restype = OSStatus
 
+    try:
+        Security.SSLSetALPNProtocols.argtypes = [SSLContextRef, CFArrayRef]
+        Security.SSLSetALPNProtocols.restype = OSStatus
+    except AttributeError:
+        # Supported only in 10.12+
+        pass
+
     Security.SecCopyErrorMessageString.argtypes = [OSStatus, c_void_p]
     Security.SecCopyErrorMessageString.restype = CFStringRef
 
@@ -415,6 +441,7 @@ class SecurityConst(object):
     kTLSProtocol1 = 4
     kTLSProtocol11 = 7
     kTLSProtocol12 = 8
+    # SecureTransport does not support TLS 1.3 even if there's a constant for it
     kTLSProtocol13 = 10
     kTLSProtocolMaxSupported = 999
 

lib/urllib3/contrib/_securetransport/low_level.py

@@ -10,13 +10,13 @@ appropriate and useful assistance to the higher-level code.
 import base64
 import ctypes
 import itertools
-import re
 import os
+import re
 import ssl
+import struct
 import tempfile
 
-from .bindings import Security, CoreFoundation, CFConst
-
+from .bindings import CFConst, CoreFoundation, Security
 
 # This regular expression is used to grab PEM data out of a PEM bundle.
 _PEM_CERTS_RE = re.compile(
@@ -56,6 +56,51 @@ def _cf_dictionary_from_tuples(tuples):
     )
 
 
+def _cfstr(py_bstr):
+    """
+    Given a Python binary data, create a CFString.
+    The string must be CFReleased by the caller.
+    """
+    c_str = ctypes.c_char_p(py_bstr)
+    cf_str = CoreFoundation.CFStringCreateWithCString(
+        CoreFoundation.kCFAllocatorDefault,
+        c_str,
+        CFConst.kCFStringEncodingUTF8,
+    )
+    return cf_str
+
+
+def _create_cfstring_array(lst):
+    """
+    Given a list of Python binary data, create an associated CFMutableArray.
+    The array must be CFReleased by the caller.
+
+    Raises an ssl.SSLError on failure.
+    """
+    cf_arr = None
+    try:
+        cf_arr = CoreFoundation.CFArrayCreateMutable(
+            CoreFoundation.kCFAllocatorDefault,
+            0,
+            ctypes.byref(CoreFoundation.kCFTypeArrayCallBacks),
+        )
+        if not cf_arr:
+            raise MemoryError("Unable to allocate memory!")
+        for item in lst:
+            cf_str = _cfstr(item)
+            if not cf_str:
+                raise MemoryError("Unable to allocate memory!")
+            try:
+                CoreFoundation.CFArrayAppendValue(cf_arr, cf_str)
+            finally:
+                CoreFoundation.CFRelease(cf_str)
+    except BaseException as e:
+        if cf_arr:
+            CoreFoundation.CFRelease(cf_arr)
+        raise ssl.SSLError("Unable to allocate array: %s" % (e,))
+    return cf_arr
+
+
 def _cf_string_to_unicode(value):
     """
     Creates a Unicode string from a CFString object. Used entirely for error
@@ -143,6 +188,7 @@ def _cert_array_from_pem(pem_bundle):
         # We only want to do that if an error occurs: otherwise, the caller
         # should free.
         CoreFoundation.CFRelease(cert_array)
+        raise
 
     return cert_array
 
@@ -326,3 +372,26 @@ def _load_client_cert_chain(keychain, *paths):
     finally:
         for obj in itertools.chain(identities, certificates):
             CoreFoundation.CFRelease(obj)
+
+
+TLS_PROTOCOL_VERSIONS = {
+    "SSLv2": (0, 2),
+    "SSLv3": (3, 0),
+    "TLSv1": (3, 1),
+    "TLSv1.1": (3, 2),
+    "TLSv1.2": (3, 3),
+}
+
+
+def _build_tls_unknown_ca_alert(version):
+    """
+    Builds a TLS alert record for an unknown CA.
+    """
+    ver_maj, ver_min = TLS_PROTOCOL_VERSIONS[version]
+    severity_fatal = 0x02
+    description_unknown_ca = 0x30
+    msg = struct.pack(">BB", severity_fatal, description_unknown_ca)
+    msg_len = len(msg)
+    record_type_alert = 0x15
+    record = struct.pack(">BBBH", record_type_alert, ver_maj, ver_min, msg_len) + msg
+    return record

lib/urllib3/contrib/appengine.py

@@ -39,24 +39,24 @@ urllib3 on Google App Engine:
 """
 
 from __future__ import absolute_import
+
 import io
 import logging
 import warnings
-from ..packages.six.moves.urllib.parse import urljoin
 
 from ..exceptions import (
     HTTPError,
     HTTPWarning,
     MaxRetryError,
     ProtocolError,
-    TimeoutError,
     SSLError,
+    TimeoutError,
 )
-
+from ..packages.six.moves.urllib.parse import urljoin
 from ..request import RequestMethods
 from ..response import HTTPResponse
-from ..util.timeout import Timeout
 from ..util.retry import Retry
+from ..util.timeout import Timeout
 from . import _appengine_environ
 
 try:
@@ -90,7 +90,7 @@ class AppEngineManager(RequestMethods):
         * If you attempt to use this on App Engine Flexible, as full socket
           support is available.
         * If a request size is more than 10 megabytes.
-        * If a response size is more than 32 megabtyes.
+        * If a response size is more than 32 megabytes.
         * If you use an unsupported request method such as OPTIONS.
 
     Beyond those cases, it will raise normal urllib3 errors.
@@ -108,17 +108,10 @@ class AppEngineManager(RequestMethods):
                 "URLFetch is not available in this environment."
             )
 
-        if is_prod_appengine_mvms():
-            raise AppEnginePlatformError(
-                "Use normal urllib3.PoolManager instead of AppEngineManager"
-                "on Managed VMs, as using URLFetch is not necessary in "
-                "this environment."
-            )
-
         warnings.warn(
             "urllib3 is using URLFetch on Google App Engine sandbox instead "
             "of sockets. To use sockets directly instead of URLFetch see "
-            "https://urllib3.readthedocs.io/en/latest/reference/urllib3.contrib.html.",
+            "https://urllib3.readthedocs.io/en/1.26.x/reference/urllib3.contrib.html.",
             AppEnginePlatformWarning,
         )
 
@@ -231,7 +224,7 @@ class AppEngineManager(RequestMethods):
                 )
 
         # Check if we should retry the HTTP response.
-        has_retry_after = bool(http_response.getheader("Retry-After"))
+        has_retry_after = bool(http_response.headers.get("Retry-After"))
         if retries.is_retry(method, http_response.status, has_retry_after):
             retries = retries.increment(method, url, response=http_response, _pool=self)
             log.debug("Retry: %s", url)

lib/urllib3/contrib/ntlmpool.py

@@ -5,12 +5,21 @@ Issue #10, see: http://code.google.com/p/urllib3/issues/detail?id=10
 """
 from __future__ import absolute_import
 
+import warnings
 from logging import getLogger
+
 from ntlm import ntlm
 
 from .. import HTTPSConnectionPool
 from ..packages.six.moves.http_client import HTTPSConnection
 
+warnings.warn(
+    "The 'urllib3.contrib.ntlmpool' module is deprecated and will be removed "
+    "in urllib3 v2.0 release, urllib3 is not able to support it properly due "
+    "to reasons listed in issue: https://github.com/urllib3/urllib3/issues/2282. "
+    "If you are a user of this module please comment in the mentioned issue.",
+    DeprecationWarning,
+)
 
 log = getLogger(__name__)
 
@@ -60,7 +69,7 @@ class NTLMConnectionPool(HTTPSConnectionPool):
         log.debug("Request headers: %s", headers)
         conn.request("GET", self.authurl, None, headers)
         res = conn.getresponse()
-        reshdr = dict(res.getheaders())
+        reshdr = dict(res.headers)
         log.debug("Response status: %s %s", res.status, res.reason)
         log.debug("Response headers: %s", reshdr)
         log.debug("Response data: %s [...]", res.read(100))
@@ -92,13 +101,11 @@ class NTLMConnectionPool(HTTPSConnectionPool):
         conn.request("GET", self.authurl, None, headers)
         res = conn.getresponse()
         log.debug("Response status: %s %s", res.status, res.reason)
-        log.debug("Response headers: %s", dict(res.getheaders()))
+        log.debug("Response headers: %s", dict(res.headers))
         log.debug("Response data: %s [...]", res.read()[:100])
         if res.status != 200:
             if res.status == 401:
-                raise Exception(
-                    "Server rejected request: wrong " "username or password"
-                )
+                raise Exception("Server rejected request: wrong username or password")
             raise Exception("Wrong server response: %s %s" % (res.status, res.reason))
 
         res.fp = None

lib/urllib3/contrib/pyopenssl.py

@@ -1,27 +1,31 @@
 """
-SSL with SNI_-support for Python 2. Follow these instructions if you would
-like to verify SSL certificates in Python 2. Note, the default libraries do
+TLS with SNI_-support for Python 2. Follow these instructions if you would
+like to verify TLS certificates in Python 2. Note, the default libraries do
 *not* do certificate checking; you need to do additional work to validate
 certificates yourself.
 
 This needs the following packages installed:
 
-* pyOpenSSL (tested with 16.0.0)
-* cryptography (minimum 1.3.4, from pyopenssl)
-* idna (minimum 2.0, from cryptography)
+* `pyOpenSSL`_ (tested with 16.0.0)
+* `cryptography`_ (minimum 1.3.4, from pyopenssl)
+* `idna`_ (minimum 2.0, from cryptography)
 
 However, pyopenssl depends on cryptography, which depends on idna, so while we
 use all three directly here we end up having relatively few packages required.
 
 You can install them with the following command:
 
-    pip install pyopenssl cryptography idna
+.. code-block:: bash
+
+    $ python -m pip install pyopenssl cryptography idna
 
 To activate certificate checking, call
 :func:`~urllib3.contrib.pyopenssl.inject_into_urllib3` from your Python code
 before you begin making HTTP requests. This can be done in a ``sitecustomize``
 module, or at any other time before your application begins using ``urllib3``,
-like this::
+like this:
+
+.. code-block:: python
 
     try:
         import urllib3.contrib.pyopenssl
@@ -35,18 +39,18 @@ when the required modules are installed.
 Activating this module also has the positive side effect of disabling SSL/TLS
 compression in Python 2 (see `CRIME attack`_).
 
-If you want to configure the default list of supported cipher suites, you can
-set the ``urllib3.contrib.pyopenssl.DEFAULT_SSL_CIPHER_LIST`` variable.
-
 .. _sni: https://en.wikipedia.org/wiki/Server_Name_Indication
 .. _crime attack: https://en.wikipedia.org/wiki/CRIME_(security_exploit)
+.. _pyopenssl: https://www.pyopenssl.org
+.. _cryptography: https://cryptography.io
+.. _idna: https://github.com/kjd/idna
 """
 from __future__ import absolute_import
 
+import OpenSSL.crypto
 import OpenSSL.SSL
 from cryptography import x509
 from cryptography.hazmat.backends.openssl import backend as openssl_backend
-from cryptography.hazmat.backends.openssl.x509 import _Certificate
 
 try:
     from cryptography.x509 import UnsupportedExtension
@@ -56,8 +60,9 @@ except ImportError:
         pass
 
 
-from socket import timeout, error as SocketError
 from io import BytesIO
+from socket import error as SocketError
+from socket import timeout
 
 try:  # Platform-specific: Python 2
     from socket import _fileobject
@@ -67,11 +72,20 @@ except ImportError:  # Platform-specific: Python 3
 
 import logging
 import ssl
-from ..packages import six
 import sys
+import warnings
 
 from .. import util
+from ..packages import six
+from ..util.ssl_ import PROTOCOL_TLS_CLIENT
 
+warnings.warn(
+    "'urllib3.contrib.pyopenssl' module is deprecated and will be removed "
+    "in a future release of urllib3 2.x. Read more in this issue: "
+    "https://github.com/urllib3/urllib3/issues/2680",
+    category=DeprecationWarning,
+    stacklevel=2,
+)
 
 __all__ = ["inject_into_urllib3", "extract_from_urllib3"]
 
@@ -81,6 +95,7 @@ HAS_SNI = True
 # Map from urllib3 to PyOpenSSL compatible parameter-values.
 _openssl_versions = {
     util.PROTOCOL_TLS: OpenSSL.SSL.SSLv23_METHOD,
+    PROTOCOL_TLS_CLIENT: OpenSSL.SSL.SSLv23_METHOD,
     ssl.PROTOCOL_TLSv1: OpenSSL.SSL.TLSv1_METHOD,
 }
 
@@ -213,9 +228,8 @@ def get_subj_alt_name(peer_cert):
     if hasattr(peer_cert, "to_cryptography"):
         cert = peer_cert.to_cryptography()
     else:
-        # This is technically using private APIs, but should work across all
-        # relevant versions before PyOpenSSL got a proper API for this.
-        cert = _Certificate(openssl_backend, peer_cert._x509)
+        der = OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1, peer_cert)
+        cert = x509.load_der_x509_certificate(der, openssl_backend)
 
     # We want to find the SAN extension. Ask Cryptography to locate it (it's
     # faster than looping in Python)
@@ -400,7 +414,6 @@ if _fileobject:  # Platform-specific: Python 2
         self._makefile_refs += 1
         return _fileobject(self, mode, bufsize, close=True)
 
-
 else:  # Platform-specific: Python 3
     makefile = backport_makefile
 
@@ -450,9 +463,12 @@ class PyOpenSSLContext(object):
             cafile = cafile.encode("utf-8")
         if capath is not None:
             capath = capath.encode("utf-8")
-        self._ctx.load_verify_locations(cafile, capath)
-        if cadata is not None:
-            self._ctx.load_verify_locations(BytesIO(cadata))
+        try:
+            self._ctx.load_verify_locations(cafile, capath)
+            if cadata is not None:
+                self._ctx.load_verify_locations(BytesIO(cadata))
+        except OpenSSL.SSL.Error as e:
+            raise ssl.SSLError("unable to load trusted certificates: %r" % e)
 
     def load_cert_chain(self, certfile, keyfile=None, password=None):
         self._ctx.use_certificate_chain_file(certfile)
@@ -462,6 +478,10 @@ class PyOpenSSLContext(object):
             self._ctx.set_passwd_cb(lambda *_: password)
         self._ctx.use_privatekey_file(keyfile or certfile)
 
+    def set_alpn_protocols(self, protocols):
+        protocols = [six.ensure_binary(p) for p in protocols]
+        return self._ctx.set_alpn_protos(protocols)
+
     def wrap_socket(
         self,
         sock,

lib/urllib3/contrib/securetransport.py

@@ -29,6 +29,8 @@ library. An enormous debt is owed to him for blazing this trail for us. For
 that reason, this code should be considered to be covered both by urllib3's
 license and by oscrypto's:
 
+.. code-block::
+
     Copyright (c) 2015-2016 Will Bond <will@wbond.net>
 
     Permission is hereby granted, free of charge, to any person obtaining a
@@ -58,16 +60,21 @@ import os.path
 import shutil
 import socket
 import ssl
+import struct
 import threading
 import weakref
 
 from .. import util
-from ._securetransport.bindings import Security, SecurityConst, CoreFoundation
+from ..packages import six
+from ..util.ssl_ import PROTOCOL_TLS_CLIENT
+from ._securetransport.bindings import CoreFoundation, Security, SecurityConst
 from ._securetransport.low_level import (
     _assert_no_error,
+    _build_tls_unknown_ca_alert,
     _cert_array_from_pem,
-    _temporary_keychain,
+    _create_cfstring_array,
     _load_client_cert_chain,
+    _temporary_keychain,
 )
 
 try:  # Platform-specific: Python 2
@@ -144,13 +151,11 @@ CIPHER_SUITES = [
 ]
 
 # Basically this is simple: for PROTOCOL_SSLv23 we turn it into a low of
-# TLSv1 and a high of TLSv1.3. For everything else, we pin to that version.
-# TLSv1 to 1.2 are supported on macOS 10.8+ and TLSv1.3 is macOS 10.13+
+# TLSv1 and a high of TLSv1.2. For everything else, we pin to that version.
+# TLSv1 to 1.2 are supported on macOS 10.8+
 _protocol_to_min_max = {
-    util.PROTOCOL_TLS: (
-        SecurityConst.kTLSProtocol1,
-        SecurityConst.kTLSProtocolMaxSupported,
-    )
+    util.PROTOCOL_TLS: (SecurityConst.kTLSProtocol1, SecurityConst.kTLSProtocol12),
+    PROTOCOL_TLS_CLIENT: (SecurityConst.kTLSProtocol1, SecurityConst.kTLSProtocol12),
 }
 
 if hasattr(ssl, "PROTOCOL_SSLv2"):
@@ -377,16 +382,55 @@ class WrappedSocket(object):
         )
         _assert_no_error(result)
 
+    def _set_alpn_protocols(self, protocols):
+        """
+        Sets up the ALPN protocols on the context.
+        """
+        if not protocols:
+            return
+        protocols_arr = _create_cfstring_array(protocols)
+        try:
+            result = Security.SSLSetALPNProtocols(self.context, protocols_arr)
+            _assert_no_error(result)
+        finally:
+            CoreFoundation.CFRelease(protocols_arr)
+
     def _custom_validate(self, verify, trust_bundle):
         """
         Called when we have set custom validation. We do this in two cases:
         first, when cert validation is entirely disabled; and second, when
         using a custom trust DB.
+        Raises an SSLError if the connection is not trusted.
         """
         # If we disabled cert validation, just say: cool.
         if not verify:
             return
 
+        successes = (
+            SecurityConst.kSecTrustResultUnspecified,
+            SecurityConst.kSecTrustResultProceed,
+        )
+        try:
+            trust_result = self._evaluate_trust(trust_bundle)
+            if trust_result in successes:
+                return
+            reason = "error code: %d" % (trust_result,)
+        except Exception as e:
+            # Do not trust on error
+            reason = "exception: %r" % (e,)
+
+        # SecureTransport does not send an alert nor shuts down the connection.
+        rec = _build_tls_unknown_ca_alert(self.version())
+        self.socket.sendall(rec)
+        # close the connection immediately
+        # l_onoff = 1, activate linger
+        # l_linger = 0, linger for 0 seoncds
+        opts = struct.pack("ii", 1, 0)
+        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, opts)
+        self.close()
+        raise ssl.SSLError("certificate verify failed, %s" % reason)
+
+    def _evaluate_trust(self, trust_bundle):
         # We want data in memory, so load it up.
         if os.path.isfile(trust_bundle):
             with open(trust_bundle, "rb") as f:
@@ -424,15 +468,7 @@ class WrappedSocket(object):
             if cert_array is not None:
                 CoreFoundation.CFRelease(cert_array)
 
-        # Ok, now we can look at what the result was.
-        successes = (
-            SecurityConst.kSecTrustResultUnspecified,
-            SecurityConst.kSecTrustResultProceed,
-        )
-        if trust_result.value not in successes:
-            raise ssl.SSLError(
-                "certificate verify failed, error code: %d" % trust_result.value
-            )
+        return trust_result.value
 
     def handshake(
         self,
@@ -444,6 +480,7 @@ class WrappedSocket(object):
         client_cert,
         client_key,
         client_key_passphrase,
+        alpn_protocols,
     ):
         """
         Actually performs the TLS handshake. This is run automatically by
@@ -484,19 +521,14 @@ class WrappedSocket(object):
         # Setup the ciphers.
         self._set_ciphers()
 
+        # Setup the ALPN protocols.
+        self._set_alpn_protocols(alpn_protocols)
+
         # Set the minimum and maximum TLS versions.
         result = Security.SSLSetProtocolVersionMin(self.context, min_version)
         _assert_no_error(result)
 
-        # TLS 1.3 isn't necessarily enabled by the OS
-        # so we have to detect when we error out and try
-        # setting TLS 1.3 if it's allowed. kTLSProtocolMaxSupported
-        # was added in macOS 10.13 along with kTLSProtocol13.
         result = Security.SSLSetProtocolVersionMax(self.context, max_version)
-        if result != 0 and max_version == SecurityConst.kTLSProtocolMaxSupported:
-            result = Security.SSLSetProtocolVersionMax(
-                self.context, SecurityConst.kTLSProtocol12
-            )
         _assert_no_error(result)
 
         # If there's a trust DB, we need to use it. We do that by telling
@@ -707,7 +739,7 @@ class WrappedSocket(object):
         )
         _assert_no_error(result)
         if protocol.value == SecurityConst.kTLSProtocol13:
-            return "TLSv1.3"
+            raise ssl.SSLError("SecureTransport does not support TLS 1.3")
         elif protocol.value == SecurityConst.kTLSProtocol12:
             return "TLSv1.2"
         elif protocol.value == SecurityConst.kTLSProtocol11:
@@ -737,7 +769,6 @@ if _fileobject:  # Platform-specific: Python 2
         self._makefile_refs += 1
         return _fileobject(self, mode, bufsize, close=True)
 
-
 else:  # Platform-specific: Python 3
 
     def makefile(self, mode="r", buffering=None, *args, **kwargs):
@@ -765,6 +796,7 @@ class SecureTransportContext(object):
         self._client_cert = None
         self._client_key = None
         self._client_key_passphrase = None
+        self._alpn_protocols = None
 
     @property
     def check_hostname(self):
@@ -830,6 +862,11 @@ class SecureTransportContext(object):
         if capath is not None:
             raise ValueError("SecureTransport does not support cert directories")
 
+        # Raise if cafile does not exist.
+        if cafile is not None:
+            with open(cafile):
+                pass
+
         self._trust_bundle = cafile or cadata
 
     def load_cert_chain(self, certfile, keyfile=None, password=None):
@@ -837,6 +874,18 @@ class SecureTransportContext(object):
         self._client_key = keyfile
         self._client_cert_passphrase = password
 
+    def set_alpn_protocols(self, protocols):
+        """
+        Sets the ALPN protocols that will later be set on the context.
+
+        Raises a NotImplementedError if ALPN is not supported.
+        """
+        if not hasattr(Security, "SSLSetALPNProtocols"):
+            raise NotImplementedError(
+                "SecureTransport supports ALPN only in macOS 10.12+"
+            )
+        self._alpn_protocols = [six.ensure_binary(p) for p in protocols]
+
     def wrap_socket(
         self,
         sock,
@@ -866,5 +915,6 @@ class SecureTransportContext(object):
             self._client_cert,
             self._client_key,
             self._client_key_passphrase,
+            self._alpn_protocols,
         )
         return wrapped_socket

lib/urllib3/contrib/socks.py

@@ -14,22 +14,26 @@ supports the following SOCKS features:
 - SOCKS5 with local DNS (``proxy_url='socks5://...``)
 - Usernames and passwords for the SOCKS proxy
 
- .. note::
-    It is recommended to use ``socks5h://`` or ``socks4a://`` schemes in
-    your ``proxy_url`` to ensure that DNS resolution is done from the remote
-    server instead of client-side when connecting to a domain name.
+.. note::
+   It is recommended to use ``socks5h://`` or ``socks4a://`` schemes in
+   your ``proxy_url`` to ensure that DNS resolution is done from the remote
+   server instead of client-side when connecting to a domain name.
 
 SOCKS4 supports IPv4 and domain names with the SOCKS4A extension. SOCKS5
 supports IPv4, IPv6, and domain names.
 
 When connecting to a SOCKS4 proxy the ``username`` portion of the ``proxy_url``
-will be sent as the ``userid`` section of the SOCKS request::
+will be sent as the ``userid`` section of the SOCKS request:
+
+.. code-block:: python
 
     proxy_url="socks4a://<userid>@proxy-host"
 
 When connecting to a SOCKS5 proxy the ``username`` and ``password`` portion
 of the ``proxy_url`` will be sent as the username/password to authenticate
-with the proxy::
+with the proxy:
+
+.. code-block:: python
 
     proxy_url="socks5h://<username>:<password>@proxy-host"
 
@@ -40,19 +44,21 @@ try:
     import socks
 except ImportError:
     import warnings
+
     from ..exceptions import DependencyWarning
 
     warnings.warn(
         (
             "SOCKS support in urllib3 requires the installation of optional "
             "dependencies: specifically, PySocks.  For more information, see "
-            "https://urllib3.readthedocs.io/en/latest/contrib.html#socks-proxies"
+            "https://urllib3.readthedocs.io/en/1.26.x/contrib.html#socks-proxies"
         ),
         DependencyWarning,
     )
     raise
 
-from socket import error as SocketError, timeout as SocketTimeout
+from socket import error as SocketError
+from socket import timeout as SocketTimeout
 
 from ..connection import HTTPConnection, HTTPSConnection
 from ..connectionpool import HTTPConnectionPool, HTTPSConnectionPool