Issue #19422: Explicitly disallow non-SOCK_STREAM sockets in the ssl module, rather than silently let them emit clear text data.
diff --git a/Lib/ssl.py b/Lib/ssl.py
index 329b9d1..666cea3 100644
--- a/Lib/ssl.py
+++ b/Lib/ssl.py
@@ -89,6 +89,7 @@
 
 from socket import socket, _fileobject, _delegate_methods, error as socket_error
 from socket import getnameinfo as _getnameinfo
+from socket import SOL_SOCKET, SO_TYPE, SOCK_STREAM
 import base64        # for DER-to-PEM translation
 import errno
 
@@ -108,6 +109,10 @@
                  ssl_version=PROTOCOL_SSLv23, ca_certs=None,
                  do_handshake_on_connect=True,
                  suppress_ragged_eofs=True, ciphers=None):
+        # Can't use sock.type as other flags (such as SOCK_NONBLOCK) get
+        # mixed in.
+        if sock.getsockopt(SOL_SOCKET, SO_TYPE) != SOCK_STREAM:
+            raise NotImplementedError("only stream sockets are supported")
         socket.__init__(self, _sock=sock._sock)
         # The initializer for socket overrides the methods send(), recv(), etc.
         # in the instancce, which we don't need -- but we want to provide the
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 6723865..c1c3384 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -232,6 +232,13 @@
         self.assertRaises(socket.error, ss.send, b'x')
         self.assertRaises(socket.error, ss.sendto, b'x', ('0.0.0.0', 0))
 
+    def test_unsupported_dtls(self):
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        self.addCleanup(s.close)
+        with self.assertRaises(NotImplementedError) as cx:
+            ssl.wrap_socket(s, cert_reqs=ssl.CERT_NONE)
+        self.assertEqual(str(cx.exception), "only stream sockets are supported")
+
 
 class NetworkedTests(unittest.TestCase):