Imported Upstream version 1.10.4

11 files changed, 455 insertions, 132 deletions

diff --git a/urllib3/__init__.py b/urllib3/__init__.py
index 4f9d4a7..f48ac4a 100644
--- a/urllib3/__init__.py
+++ b/urllib3/__init__.py
@@ -4,7 +4,7 @@ urllib3 - Thread-safe connection pooling and re-using.
 
 __author__ = 'Andrey Petrov (andrey.petrov@shazow.net)'
 __license__ = 'MIT'
-__version__ = '1.10'
+__version__ = '1.10.4'
 
 
 from .connectionpool import (
@@ -55,9 +55,12 @@ def add_stderr_logger(level=logging.DEBUG):
 del NullHandler
 
 
-# Set security warning to always go off by default.
 import warnings
-warnings.simplefilter('always', exceptions.SecurityWarning)
+# SecurityWarning's always go off by default.
+warnings.simplefilter('always', exceptions.SecurityWarning, append=True)
+# InsecurePlatformWarning's don't vary between requests, so we keep it default.
+warnings.simplefilter('default', exceptions.InsecurePlatformWarning,
+                      append=True)
 
 def disable_warnings(category=exceptions.HTTPWarning):
     """
diff --git a/urllib3/_collections.py b/urllib3/_collections.py
index 784342a..279416c 100644
--- a/urllib3/_collections.py
+++ b/urllib3/_collections.py
@@ -1,7 +1,7 @@
 from collections import Mapping, MutableMapping
 try:
     from threading import RLock
-except ImportError: # Platform-specific: No threads available
+except ImportError:  # Platform-specific: No threads available
     class RLock:
         def __enter__(self):
             pass
@@ -10,11 +10,11 @@ except ImportError: # Platform-specific: No threads available
             pass
 
 
-try: # Python 2.7+
+try:  # Python 2.7+
     from collections import OrderedDict
 except ImportError:
     from .packages.ordered_dict import OrderedDict
-from .packages.six import iterkeys, itervalues
+from .packages.six import iterkeys, itervalues, PY3
 
 
 __all__ = ['RecentlyUsedContainer', 'HTTPHeaderDict']
@@ -97,7 +97,14 @@ class RecentlyUsedContainer(MutableMapping):
             return list(iterkeys(self._container))
 
 
-class HTTPHeaderDict(MutableMapping):
+_dict_setitem = dict.__setitem__
+_dict_getitem = dict.__getitem__
+_dict_delitem = dict.__delitem__
+_dict_contains = dict.__contains__
+_dict_setdefault = dict.setdefault
+
+
+class HTTPHeaderDict(dict):
     """
     :param headers:
         An iterable of field-value pairs. Must not contain multiple field names
@@ -129,25 +136,75 @@ class HTTPHeaderDict(MutableMapping):
     'foo=bar, baz=quxx'
     >>> headers['Content-Length']
     '7'
-
-    If you want to access the raw headers with their original casing
-    for debugging purposes you can access the private ``._data`` attribute
-    which is a normal python ``dict`` that maps the case-insensitive key to a
-    list of tuples stored as (case-sensitive-original-name, value). Using the
-    structure from above as our example:
-
-    >>> headers._data
-    {'set-cookie': [('Set-Cookie', 'foo=bar'), ('set-cookie', 'baz=quxx')],
-    'content-length': [('content-length', '7')]}
     """
 
     def __init__(self, headers=None, **kwargs):
-        self._data = {}
-        if headers is None:
-            headers = {}
-        self.update(headers, **kwargs)
+        dict.__init__(self)
+        if headers is not None:
+            if isinstance(headers, HTTPHeaderDict):
+                self._copy_from(headers)
+            else:
+                self.extend(headers)
+        if kwargs:
+            self.extend(kwargs)
+
+    def __setitem__(self, key, val):
+        return _dict_setitem(self, key.lower(), (key, val))
+
+    def __getitem__(self, key):
+        val = _dict_getitem(self, key.lower())
+        return ', '.join(val[1:])
+
+    def __delitem__(self, key):
+        return _dict_delitem(self, key.lower())
 
-    def add(self, key, value):
+    def __contains__(self, key):
+        return _dict_contains(self, key.lower())
+
+    def __eq__(self, other):
+        if not isinstance(other, Mapping) and not hasattr(other, 'keys'):
+            return False
+        if not isinstance(other, type(self)):
+            other = type(self)(other)
+        return dict((k1, self[k1]) for k1 in self) == dict((k2, other[k2]) for k2 in other)
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    values = MutableMapping.values
+    get = MutableMapping.get
+    update = MutableMapping.update
+    
+    if not PY3: # Python 2
+        iterkeys = MutableMapping.iterkeys
+        itervalues = MutableMapping.itervalues
+
+    __marker = object()
+
+    def pop(self, key, default=__marker):
+        '''D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
+          If key is not found, d is returned if given, otherwise KeyError is raised.
+        '''
+        # Using the MutableMapping function directly fails due to the private marker.
+        # Using ordinary dict.pop would expose the internal structures.
+        # So let's reinvent the wheel.
+        try:
+            value = self[key]
+        except KeyError:
+            if default is self.__marker:
+                raise
+            return default
+        else:
+            del self[key]
+            return value
+
+    def discard(self, key):
+        try:
+            del self[key]
+        except KeyError:
+            pass
+
+    def add(self, key, val):
         """Adds a (name, value) pair, doesn't overwrite the value if it already
         exists.
 
@@ -156,43 +213,111 @@ class HTTPHeaderDict(MutableMapping):
         >>> headers['foo']
         'bar, baz'
         """
-        self._data.setdefault(key.lower(), []).append((key, value))
+        key_lower = key.lower()
+        new_vals = key, val
+        # Keep the common case aka no item present as fast as possible
+        vals = _dict_setdefault(self, key_lower, new_vals)
+        if new_vals is not vals:
+            # new_vals was not inserted, as there was a previous one
+            if isinstance(vals, list):
+                # If already several items got inserted, we have a list
+                vals.append(val)
+            else:
+                # vals should be a tuple then, i.e. only one item so far
+                # Need to convert the tuple to list for further extension
+                _dict_setitem(self, key_lower, [vals[0], vals[1], val])
+
+    def extend(self, *args, **kwargs):
+        """Generic import function for any type of header-like object.
+        Adapted version of MutableMapping.update in order to insert items
+        with self.add instead of self.__setitem__
+        """
+        if len(args) > 1:
+            raise TypeError("extend() takes at most 1 positional "
+                            "arguments ({} given)".format(len(args)))
+        other = args[0] if len(args) >= 1 else ()
+        
+        if isinstance(other, HTTPHeaderDict):
+            for key, val in other.iteritems():
+                self.add(key, val)
+        elif isinstance(other, Mapping):
+            for key in other:
+                self.add(key, other[key])
+        elif hasattr(other, "keys"):
+            for key in other.keys():
+                self.add(key, other[key])
+        else:
+            for key, value in other:
+                self.add(key, value)
+
+        for key, value in kwargs.items():
+            self.add(key, value)
 
     def getlist(self, key):
         """Returns a list of all the values for the named field. Returns an
         empty list if the key doesn't exist."""
-        return self[key].split(', ') if key in self else []
-
-    def copy(self):
-        h = HTTPHeaderDict()
-        for key in self._data:
-            for rawkey, value in self._data[key]:
-                h.add(rawkey, value)
-        return h
-
-    def __eq__(self, other):
-        if not isinstance(other, Mapping):
-            return False
-        other = HTTPHeaderDict(other)
-        return dict((k1, self[k1]) for k1 in self._data) == \
-                dict((k2, other[k2]) for k2 in other._data)
-
-    def __getitem__(self, key):
-        values = self._data[key.lower()]
-        return ', '.join(value[1] for value in values)
-
-    def __setitem__(self, key, value):
-        self._data[key.lower()] = [(key, value)]
+        try:
+            vals = _dict_getitem(self, key.lower())
+        except KeyError:
+            return []
+        else:
+            if isinstance(vals, tuple):
+                return [vals[1]]
+            else:
+                return vals[1:]
+
+    # Backwards compatibility for httplib
+    getheaders = getlist
+    getallmatchingheaders = getlist
+    iget = getlist
 
-    def __delitem__(self, key):
-        del self._data[key.lower()]
+    def __repr__(self):
+        return "%s(%s)" % (type(self).__name__, dict(self.itermerged()))
 
-    def __len__(self):
-        return len(self._data)
+    def _copy_from(self, other):
+        for key in other:
+            val = _dict_getitem(other, key)
+            if isinstance(val, list):
+                # Don't need to convert tuples
+                val = list(val)
+            _dict_setitem(self, key, val)
 
-    def __iter__(self):
-        for headers in itervalues(self._data):
-            yield headers[0][0]
-
-    def __repr__(self):
-        return '%s(%r)' % (self.__class__.__name__, dict(self.items()))
+    def copy(self):
+        clone = type(self)()
+        clone._copy_from(self)
+        return clone
+
+    def iteritems(self):
+        """Iterate over all header lines, including duplicate ones."""
+        for key in self:
+            vals = _dict_getitem(self, key)
+            for val in vals[1:]:
+                yield vals[0], val
+
+    def itermerged(self):
+        """Iterate over all headers, merging duplicate ones together."""
+        for key in self:
+            val = _dict_getitem(self, key)
+            yield val[0], ', '.join(val[1:])
+
+    def items(self):
+        return list(self.iteritems())
+
+    @classmethod
+    def from_httplib(cls, message): # Python 2
+        """Read headers from a Python 2 httplib message object."""
+        # python2.7 does not expose a proper API for exporting multiheaders
+        # efficiently. This function re-reads raw lines from the message 
+        # object and extracts the multiheaders properly.
+        headers = []
+         
+        for line in message.headers:
+            if line.startswith((' ', '\t')):
+                key, value = headers[-1]
+                headers[-1] = (key, value + '\r\n' + line.rstrip())
+                continue
+    
+            key, value = line.split(':', 1)
+            headers.append((key, value.strip()))
+
+        return cls(headers)
diff --git a/urllib3/connection.py b/urllib3/connection.py
index e5de769..2a8c359 100644
--- a/urllib3/connection.py
+++ b/urllib3/connection.py
@@ -260,3 +260,5 @@ if ssl:
     # Make a copy for testing.
     UnverifiedHTTPSConnection = HTTPSConnection
     HTTPSConnection = VerifiedHTTPSConnection
+else:
+    HTTPSConnection = DummyConnection
diff --git a/urllib3/connectionpool.py b/urllib3/connectionpool.py
index 8bdf228..117269a 100644
--- a/urllib3/connectionpool.py
+++ b/urllib3/connectionpool.py
@@ -72,6 +72,21 @@ class ConnectionPool(object):
         return '%s(host=%r, port=%r)' % (type(self).__name__,
                                          self.host, self.port)
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.close()
+        # Return False to re-raise any potential exceptions
+        return False
+
+    def close():
+        """
+        Close all pooled connections and disable the pool.
+        """
+        pass
+
+
 # This is taken from http://hg.python.org/cpython/file/7aaba721ebc0/Lib/socket.py#l252
 _blocking_errnos = set([errno.EAGAIN, errno.EWOULDBLOCK])
 
@@ -353,7 +368,7 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
 
         # Receive the response from the server
         try:
-            try:  # Python 2.7+, use buffering of HTTP responses
+            try:  # Python 2.7, use buffering of HTTP responses
                 httplib_response = conn.getresponse(buffering=True)
             except TypeError:  # Python 2.6 and older
                 httplib_response = conn.getresponse()
@@ -558,6 +573,14 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
                 conn = None
             raise SSLError(e)
 
+        except SSLError:
+            # Treat SSLError separately from BaseSSLError to preserve
+            # traceback.
+            if conn:
+                conn.close()
+                conn = None
+            raise
+
         except (TimeoutError, HTTPException, SocketError, ConnectionError) as e:
             if conn:
                 # Discard the connection for these exceptions. It will be
@@ -565,14 +588,13 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
                 conn.close()
                 conn = None
 
-            stacktrace = sys.exc_info()[2]
             if isinstance(e, SocketError) and self.proxy:
                 e = ProxyError('Cannot connect to proxy.', e)
             elif isinstance(e, (SocketError, HTTPException)):
                 e = ProtocolError('Connection aborted.', e)
 
-            retries = retries.increment(method, url, error=e,
-                                        _pool=self, _stacktrace=stacktrace)
+            retries = retries.increment(method, url, error=e, _pool=self,
+                                        _stacktrace=sys.exc_info()[2])
             retries.sleep()
 
             # Keep track of the error for the retry warning.
@@ -713,7 +735,6 @@ class HTTPSConnectionPool(HTTPConnectionPool):
                  % (self.num_connections, self.host))
 
         if not self.ConnectionCls or self.ConnectionCls is DummyConnection:
-            # Platform-specific: Python without ssl
             raise SSLError("Can't connect to HTTPS URL because the SSL "
                            "module is not available.")
 
diff --git a/urllib3/contrib/pyopenssl.py b/urllib3/contrib/pyopenssl.py
index ee657fb..b2c34a8 100644
--- a/urllib3/contrib/pyopenssl.py
+++ b/urllib3/contrib/pyopenssl.py
@@ -38,8 +38,6 @@ Module Variables
 ----------------
 
 :var DEFAULT_SSL_CIPHER_LIST: The list of supported SSL/TLS cipher suites.
-    Default: ``ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:
-    ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS``
 
 .. _sni: https://en.wikipedia.org/wiki/Server_Name_Indication
 .. _crime attack: https://en.wikipedia.org/wiki/CRIME_(security_exploit)
@@ -85,22 +83,7 @@ _openssl_verify = {
                        + OpenSSL.SSL.VERIFY_FAIL_IF_NO_PEER_CERT,
 }
 
-# A secure default.
-# Sources for more information on TLS ciphers:
-#
-# - https://wiki.mozilla.org/Security/Server_Side_TLS
-# - https://www.ssllabs.com/projects/best-practices/index.html
-# - https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
-#
-# The general intent is:
-# - Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE),
-# - prefer ECDHE over DHE for better performance,
-# - prefer any AES-GCM over any AES-CBC for better performance and security,
-# - use 3DES as fallback which is secure but slow,
-# - disable NULL authentication, MD5 MACs and DSS for security reasons.
-DEFAULT_SSL_CIPHER_LIST = "ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:" + \
-    "ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:" + \
-    "!aNULL:!MD5:!DSS"
+DEFAULT_SSL_CIPHER_LIST = util.ssl_.DEFAULT_CIPHERS
 
 
 orig_util_HAS_SNI = util.HAS_SNI
@@ -299,7 +282,9 @@ def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
         try:
             cnx.do_handshake()
         except OpenSSL.SSL.WantReadError:
-            select.select([sock], [], [])
+            rd, _, _ = select.select([sock], [], [], sock.gettimeout())
+            if not rd:
+                raise timeout('select timed out')
             continue
         except OpenSSL.SSL.Error as e:
             raise ssl.SSLError('bad handshake', e)
diff --git a/urllib3/exceptions.py b/urllib3/exceptions.py
index 0c6fd3c..31bda1c 100644
--- a/urllib3/exceptions.py
+++ b/urllib3/exceptions.py
@@ -157,3 +157,13 @@ class InsecureRequestWarning(SecurityWarning):
 class SystemTimeWarning(SecurityWarning):
     "Warned when system time is suspected to be wrong"
     pass
+
+
+class InsecurePlatformWarning(SecurityWarning):
+    "Warned when certain SSL configuration is not available on a platform."
+    pass
+
+
+class ResponseNotChunked(ProtocolError, ValueError):
+    "Response needs to be chunked in order to read it as chunks."
+    pass
diff --git a/urllib3/poolmanager.py b/urllib3/poolmanager.py
index 515dc96..b8d1e74 100644
--- a/urllib3/poolmanager.py
+++ b/urllib3/poolmanager.py
@@ -8,7 +8,7 @@ except ImportError:
 from ._collections import RecentlyUsedContainer
 from .connectionpool import HTTPConnectionPool, HTTPSConnectionPool
 from .connectionpool import port_by_scheme
-from .exceptions import LocationValueError
+from .exceptions import LocationValueError, MaxRetryError
 from .request import RequestMethods
 from .util.url import parse_url
 from .util.retry import Retry
@@ -64,6 +64,14 @@ class PoolManager(RequestMethods):
         self.pools = RecentlyUsedContainer(num_pools,
                                            dispose_func=lambda p: p.close())
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.clear()
+        # Return False to re-raise any potential exceptions
+        return False
+
     def _new_pool(self, scheme, host, port):
         """
         Create a new :class:`ConnectionPool` based on host, port and scheme.
@@ -167,7 +175,14 @@ class PoolManager(RequestMethods):
         if not isinstance(retries, Retry):
             retries = Retry.from_int(retries, redirect=redirect)
 
-        kw['retries'] = retries.increment(method, redirect_location)
+        try:
+            retries = retries.increment(method, url, response=response, _pool=conn)
+        except MaxRetryError:
+            if retries.raise_on_redirect:
+                raise
+            return response
+
+        kw['retries'] = retries
         kw['redirect'] = redirect
 
         log.info("Redirecting %s -> %s" % (url, redirect_location))
diff --git a/urllib3/response.py b/urllib3/response.py
index e69de95..24140c4 100644
--- a/urllib3/response.py
+++ b/urllib3/response.py
@@ -1,15 +1,20 @@
+try:
+    import http.client as httplib
+except ImportError:
+    import httplib
 import zlib
 import io
 from socket import timeout as SocketTimeout
 
 from ._collections import HTTPHeaderDict
-from .exceptions import ProtocolError, DecodeError, ReadTimeoutError
-from .packages.six import string_types as basestring, binary_type
+from .exceptions import (
+    ProtocolError, DecodeError, ReadTimeoutError, ResponseNotChunked
+)
+from .packages.six import string_types as basestring, binary_type, PY3
 from .connection import HTTPException, BaseSSLError
 from .util.response import is_fp_closed
 
 
-
 class DeflateDecoder(object):
 
     def __init__(self):
@@ -21,6 +26,9 @@ class DeflateDecoder(object):
         return getattr(self._obj, name)
 
     def decompress(self, data):
+        if not data:
+            return data
+
         if not self._first_try:
             return self._obj.decompress(data)
 
@@ -36,9 +44,23 @@ class DeflateDecoder(object):
                 self._data = None
 
 
+class GzipDecoder(object):
+
+    def __init__(self):
+        self._obj = zlib.decompressobj(16 + zlib.MAX_WBITS)
+
+    def __getattr__(self, name):
+        return getattr(self._obj, name)
+
+    def decompress(self, data):
+        if not data:
+            return data
+        return self._obj.decompress(data)
+
+
 def _get_decoder(mode):
     if mode == 'gzip':
-        return zlib.decompressobj(16 + zlib.MAX_WBITS)
+        return GzipDecoder()
 
     return DeflateDecoder()
 
@@ -76,9 +98,10 @@ class HTTPResponse(io.IOBase):
                  strict=0, preload_content=True, decode_content=True,
                  original_response=None, pool=None, connection=None):
 
-        self.headers = HTTPHeaderDict()
-        if headers:
-            self.headers.update(headers)
+        if isinstance(headers, HTTPHeaderDict):
+            self.headers = headers
+        else:
+            self.headers = HTTPHeaderDict(headers)
         self.status = status
         self.version = version
         self.reason = reason
@@ -100,7 +123,17 @@ class HTTPResponse(io.IOBase):
         if hasattr(body, 'read'):
             self._fp = body
 
-        if preload_content and not self._body:
+        # Are we using the chunked-style of transfer encoding?
+        self.chunked = False
+        self.chunk_left = None
+        tr_enc = self.headers.get('transfer-encoding', '').lower()
+        # Don't incur the penalty of creating a list and then discarding it
+        encodings = (enc.strip() for enc in tr_enc.split(","))
+        if "chunked" in encodings:
+            self.chunked = True
+
+        # We certainly don't want to preload content when the response is chunked.
+        if not self.chunked and preload_content and not self._body:
             self._body = self.read(decode_content=decode_content)
 
     def get_redirect_location(self):
@@ -140,6 +173,35 @@ class HTTPResponse(io.IOBase):
         """
         return self._fp_bytes_read
 
+    def _init_decoder(self):
+        """
+        Set-up the _decoder attribute if necessar.
+        """
+        # Note: content-encoding value should be case-insensitive, per RFC 7230
+        # Section 3.2
+        content_encoding = self.headers.get('content-encoding', '').lower()
+        if self._decoder is None and content_encoding in self.CONTENT_DECODERS:
+            self._decoder = _get_decoder(content_encoding)
+
+    def _decode(self, data, decode_content, flush_decoder):
+        """
+        Decode the data passed in and potentially flush the decoder.
+        """
+        try:
+            if decode_content and self._decoder:
+                data = self._decoder.decompress(data)
+        except (IOError, zlib.error) as e:
+            content_encoding = self.headers.get('content-encoding', '').lower()
+            raise DecodeError(
+                "Received response with content-encoding: %s, but "
+                "failed to decode it." % content_encoding, e)
+
+        if flush_decoder and decode_content and self._decoder:
+            buf = self._decoder.decompress(binary_type())
+            data += buf + self._decoder.flush()
+
+        return data
+
     def read(self, amt=None, decode_content=None, cache_content=False):
         """
         Similar to :meth:`httplib.HTTPResponse.read`, but with two additional
@@ -161,12 +223,7 @@ class HTTPResponse(io.IOBase):
             after having ``.read()`` the file object. (Overridden if ``amt`` is
             set.)
         """
-        # Note: content-encoding value should be case-insensitive, per RFC 7230
-        # Section 3.2
-        content_encoding = self.headers.get('content-encoding', '').lower()
-        if self._decoder is None:
-            if content_encoding in self.CONTENT_DECODERS:
-                self._decoder = _get_decoder(content_encoding)
+        self._init_decoder()
         if decode_content is None:
             decode_content = self.decode_content
 
@@ -202,7 +259,7 @@ class HTTPResponse(io.IOBase):
 
             except BaseSSLError as e:
                 # FIXME: Is there a better way to differentiate between SSLErrors?
-                if not 'read operation timed out' in str(e):  # Defensive:
+                if 'read operation timed out' not in str(e):  # Defensive:
                     # This shouldn't happen but just in case we're missing an edge
                     # case, let's avoid swallowing SSL errors.
                     raise
@@ -215,17 +272,7 @@ class HTTPResponse(io.IOBase):
 
             self._fp_bytes_read += len(data)
 
-            try:
-                if decode_content and self._decoder:
-                    data = self._decoder.decompress(data)
-            except (IOError, zlib.error) as e:
-                raise DecodeError(
-                    "Received response with content-encoding: %s, but "
-                    "failed to decode it." % content_encoding, e)
-
-            if flush_decoder and decode_content and self._decoder:
-                buf = self._decoder.decompress(binary_type())
-                data += buf + self._decoder.flush()
+            data = self._decode(data, decode_content, flush_decoder)
 
             if cache_content:
                 self._body = data
@@ -252,11 +299,15 @@ class HTTPResponse(io.IOBase):
             If True, will attempt to decode the body based on the
             'content-encoding' header.
         """
-        while not is_fp_closed(self._fp):
-            data = self.read(amt=amt, decode_content=decode_content)
+        if self.chunked:
+            for line in self.read_chunked(amt, decode_content=decode_content):
+                yield line
+        else:
+            while not is_fp_closed(self._fp):
+                data = self.read(amt=amt, decode_content=decode_content)
 
-            if data:
-                yield data
+                if data:
+                    yield data
 
     @classmethod
     def from_httplib(ResponseCls, r, **response_kw):
@@ -267,14 +318,16 @@ class HTTPResponse(io.IOBase):
         Remaining parameters are passed to the HTTPResponse constructor, along
         with ``original_response=r``.
         """
-
-        headers = HTTPHeaderDict()
-        for k, v in r.getheaders():
-            headers.add(k, v)
+        headers = r.msg
+        if not isinstance(headers, HTTPHeaderDict):
+            if PY3: # Python 3
+                headers = HTTPHeaderDict(headers.items())
+            else: # Python 2
+                headers = HTTPHeaderDict.from_httplib(headers)
 
         # HTTPResponse objects in Python 3 don't have a .strict attribute
         strict = getattr(r, 'strict', 0)
-        return ResponseCls(body=r,
+        resp = ResponseCls(body=r,
                            headers=headers,
                            status=r.status,
                            version=r.version,
@@ -282,6 +335,7 @@ class HTTPResponse(io.IOBase):
                            strict=strict,
                            original_response=r,
                            **response_kw)
+        return resp
 
     # Backwards-compatibility methods for httplib.HTTPResponse
     def getheaders(self):
@@ -331,3 +385,82 @@ class HTTPResponse(io.IOBase):
         else:
             b[:len(temp)] = temp
             return len(temp)
+
+    def _update_chunk_length(self):
+        # First, we'll figure out length of a chunk and then
+        # we'll try to read it from socket.
+        if self.chunk_left is not None:
+            return
+        line = self._fp.fp.readline()
+        line = line.split(b';', 1)[0]
+        try:
+            self.chunk_left = int(line, 16)
+        except ValueError:
+            # Invalid chunked protocol response, abort.
+            self.close()
+            raise httplib.IncompleteRead(line)
+
+    def _handle_chunk(self, amt):
+        returned_chunk = None
+        if amt is None:
+            chunk = self._fp._safe_read(self.chunk_left)
+            returned_chunk = chunk
+            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
+            self.chunk_left = None
+        elif amt < self.chunk_left:
+            value = self._fp._safe_read(amt)
+            self.chunk_left = self.chunk_left - amt
+            returned_chunk = value
+        elif amt == self.chunk_left:
+            value = self._fp._safe_read(amt)
+            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
+            self.chunk_left = None
+            returned_chunk = value
+        else:  # amt > self.chunk_left
+            returned_chunk = self._fp._safe_read(self.chunk_left)
+            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.
+            self.chunk_left = None
+        return returned_chunk
+
+    def read_chunked(self, amt=None, decode_content=None):
+        """
+        Similar to :meth:`HTTPResponse.read`, but with an additional
+        parameter: ``decode_content``.
+
+        :param decode_content:
+            If True, will attempt to decode the body based on the
+            'content-encoding' header.
+        """
+        self._init_decoder()
+        # FIXME: Rewrite this method and make it a class with a better structured logic.
+        if not self.chunked:
+            raise ResponseNotChunked("Response is not chunked. "
+                "Header 'transfer-encoding: chunked' is missing.")
+
+        if self._original_response and self._original_response._method.upper() == 'HEAD':
+            # Don't bother reading the body of a HEAD request.
+            # FIXME: Can we do this somehow without accessing private httplib _method?
+            self._original_response.close()
+            return
+
+        while True:
+            self._update_chunk_length()
+            if self.chunk_left == 0:
+                break
+            chunk = self._handle_chunk(amt)
+            yield self._decode(chunk, decode_content=decode_content,
+                               flush_decoder=True)
+
+        # Chunk content ends with \r\n: discard it.
+        while True:
+            line = self._fp.fp.readline()
+            if not line:
+                # Some sites may not end with '\r\n'.
+                break
+            if line == b'\r\n':
+                break
+
+        # We read everything; close the "file".
+        if self._original_response:
+            self._original_response.close()
+        self.release_conn()
diff --git a/urllib3/util/connection.py b/urllib3/util/connection.py
index 2156993..859aec6 100644
--- a/urllib3/util/connection.py
+++ b/urllib3/util/connection.py
@@ -82,6 +82,7 @@ def create_connection(address, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
             err = _
             if sock is not None:
                 sock.close()
+                sock = None
 
     if err is not None:
         raise err
diff --git a/urllib3/util/ssl_.py b/urllib3/util/ssl_.py
index a788b1b..b846d42 100644
--- a/urllib3/util/ssl_.py
+++ b/urllib3/util/ssl_.py
@@ -1,7 +1,7 @@
 from binascii import hexlify, unhexlify
-from hashlib import md5, sha1
+from hashlib import md5, sha1, sha256
 
-from ..exceptions import SSLError
+from ..exceptions import SSLError, InsecurePlatformWarning
 
 
 SSLContext = None
@@ -9,9 +9,10 @@ HAS_SNI = False
 create_default_context = None
 
 import errno
-import ssl
+import warnings
 
 try:  # Test for SSL features
+    import ssl
     from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23
     from ssl import HAS_SNI  # Has SNI?
 except ImportError:
@@ -24,14 +25,24 @@ except ImportError:
     OP_NO_SSLv2, OP_NO_SSLv3 = 0x1000000, 0x2000000
     OP_NO_COMPRESSION = 0x20000
 
-try:
-    from ssl import _DEFAULT_CIPHERS
-except ImportError:
-    _DEFAULT_CIPHERS = (
-        'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:'
-        'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:ECDH+RC4:'
-        'DH+RC4:RSA+RC4:!aNULL:!eNULL:!MD5'
-    )
+# A secure default.
+# Sources for more information on TLS ciphers:
+#
+# - https://wiki.mozilla.org/Security/Server_Side_TLS
+# - https://www.ssllabs.com/projects/best-practices/index.html
+# - https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
+#
+# The general intent is:
+# - Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE),
+# - prefer ECDHE over DHE for better performance,
+# - prefer any AES-GCM over any AES-CBC for better performance and security,
+# - use 3DES as fallback which is secure but slow,
+# - disable NULL authentication, MD5 MACs and DSS for security reasons.
+DEFAULT_CIPHERS = (
+    'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:'
+    'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:!aNULL:'
+    '!eNULL:!MD5'
+)
 
 try:
     from ssl import SSLContext  # Modern SSL?
@@ -39,7 +50,8 @@ except ImportError:
     import sys
 
     class SSLContext(object):  # Platform-specific: Python 2 & 3.1
-        supports_set_ciphers = sys.version_info >= (2, 7)
+        supports_set_ciphers = ((2, 7) <= sys.version_info < (3,) or
+                                (3, 2) <= sys.version_info)
 
         def __init__(self, protocol_version):
             self.protocol = protocol_version
@@ -69,6 +81,14 @@ except ImportError:
             self.ciphers = cipher_suite
 
         def wrap_socket(self, socket, server_hostname=None):
+            warnings.warn(
+                'A true SSLContext object is not available. This prevents '
+                'urllib3 from configuring SSL appropriately and may cause '
+                'certain SSL connections to fail. For more information, see '
+                'https://urllib3.readthedocs.org/en/latest/security.html'
+                '#insecureplatformwarning.',
+                InsecurePlatformWarning
+            )
             kwargs = {
                 'keyfile': self.keyfile,
                 'certfile': self.certfile,
@@ -96,7 +116,8 @@ def assert_fingerprint(cert, fingerprint):
     # this digest.
     hashfunc_map = {
         16: md5,
-        20: sha1
+        20: sha1,
+        32: sha256,
     }
 
     fingerprint = fingerprint.replace(':', '').lower()
@@ -157,7 +178,7 @@ def resolve_ssl_version(candidate):
     return candidate
 
 
-def create_urllib3_context(ssl_version=None, cert_reqs=ssl.CERT_REQUIRED,
+def create_urllib3_context(ssl_version=None, cert_reqs=None,
                            options=None, ciphers=None):
     """All arguments have the same meaning as ``ssl_wrap_socket``.
 
@@ -194,6 +215,9 @@ def create_urllib3_context(ssl_version=None, cert_reqs=ssl.CERT_REQUIRED,
     """
     context = SSLContext(ssl_version or ssl.PROTOCOL_SSLv23)
 
+    # Setting the default here, as we may have no ssl module on import
+    cert_reqs = ssl.CERT_REQUIRED if cert_reqs is None else cert_reqs
+
     if options is None:
         options = 0
         # SSLv2 is easily broken and is considered harmful and dangerous
@@ -207,11 +231,13 @@ def create_urllib3_context(ssl_version=None, cert_reqs=ssl.CERT_REQUIRED,
     context.options |= options
 
     if getattr(context, 'supports_set_ciphers', True):  # Platform-specific: Python 2.6
-        context.set_ciphers(ciphers or _DEFAULT_CIPHERS)
+        context.set_ciphers(ciphers or DEFAULT_CIPHERS)
 
     context.verify_mode = cert_reqs
     if getattr(context, 'check_hostname', None) is not None:  # Platform-specific: Python 3.2
-        context.check_hostname = (context.verify_mode == ssl.CERT_REQUIRED)
+        # We do our own verification, including fingerprints and alternative
+        # hostnames. So disable it here
+        context.check_hostname = False
     return context
 
 
diff --git a/urllib3/util/url.py b/urllib3/util/url.py
index b2ec834..e58050c 100644
--- a/urllib3/util/url.py
+++ b/urllib3/util/url.py
@@ -15,6 +15,8 @@ class Url(namedtuple('Url', url_attrs)):
 
     def __new__(cls, scheme=None, auth=None, host=None, port=None, path=None,
                 query=None, fragment=None):
+        if path and not path.startswith('/'):
+            path = '/' + path
         return super(Url, cls).__new__(cls, scheme, auth, host, port, path,
                                        query, fragment)