bpo-27340: Use memoryview in SSLSocket.sendall() (#3384)

* bpo-27340: Use memoryview in SSLSocket.sendall()

SSLSocket.sendall() now uses memoryview to create slices of data. This fix
support for all bytes-like object. It is also more efficient and avoids
costly copies.
Signed-off-by: Christian Heimes <christian@python.org>

* Cast view to bytes, fix typo
Signed-off-by: Christian Heimes <christian@python.org>

Lib/ssl.py

@@ -959,10 +959,11 @@ class SSLSocket(socket):
                 raise ValueError(
                     "non-zero flags not allowed in calls to sendall() on %s" %
                     self.__class__)
-            amount = len(data)
             count = 0
-            while (count < amount):
-                v = self.send(data[count:])
+            with memoryview(data) as view, view.cast("B") as byte_view:
+                amount = len(byte_view)
+                while count < amount:
+                    v = self.send(byte_view[count:])
                     count += v
         else:
             return socket.sendall(self, data, flags)

Lib/test/test_ssl.py

@@ -18,6 +18,10 @@ import asyncore
 import weakref
 import platform
 import functools
+try:
+    import ctypes
+except ImportError:
+    ctypes = None
 
 ssl = support.import_module("ssl")
 
@@ -2891,6 +2895,13 @@ class ThreadedTests(unittest.TestCase):
             self.assertEqual(s.read(-1, buffer), len(data))
             self.assertEqual(buffer, data)
 
+            # sendall accepts bytes-like objects
+            if ctypes is not None:
+                ubyte = ctypes.c_ubyte * len(data)
+                byteslike = ubyte.from_buffer_copy(data)
+                s.sendall(byteslike)
+                self.assertEqual(s.read(), data)
+
             # Make sure sendmsg et al are disallowed to avoid
             # inadvertent disclosure of data and/or corruption
             # of the encrypted data stream
@@ -2898,7 +2909,6 @@ class ThreadedTests(unittest.TestCase):
             self.assertRaises(NotImplementedError, s.recvmsg, 100)
             self.assertRaises(NotImplementedError,
                               s.recvmsg_into, bytearray(100))
-
             s.write(b"over\n")
 
             self.assertRaises(ValueError, s.recv, -1)

Misc/NEWS.d/next/Library/2017-09-06-06-50-41.bpo-27340.GgekV5.rst

+SSLSocket.sendall() now uses memoryview to create slices of data. This fixes
+support for all bytes-like object. It is also more efficient and avoids
+costly copies.