Linux port

With this change all unit tests pass on the Linux platform (tested on
Ubuntu 12.04.1 LTS). demux/__init__.py has been adjusted temporarily so as
to load the routing demux on Linux until the osnet demux is ready.

Testing on Linux exposed an issue where comparison of the ssl object value from
cookie callbacks failed to compare equal to the value stored in the
SSLConnection callback object. This was because the callback function signature
of c_void_p for this parameter produced a 64-bit value if the 32nd bit was set
(as opposed to producing a negative integer 32-bit value). Changing the
signature from c_void_p to c_int for this parameter fixes the issue.

dtls/demux/__init__.py

@@ -21,6 +21,7 @@ import sys
 if sys.platform.startswith('win') or sys.platform.startswith('cygwin'):
     from router import UDPDemux
 else:
-    from osnet import UDPDemux
+    #from osnet import UDPDemux
+    from router import UDPDemux
 
 __all__ = ["UDPDemux"]

dtls/openssl.py

@@ -616,9 +616,9 @@ def SSL_CTX_set_read_ahead(ctx, m):
     # Returns the previous value of m
     _SSL_CTX_ctrl(ctx, SSL_CTRL_SET_READ_AHEAD, m, None)
 
-_rint_voidp_ubytep_uintp = CFUNCTYPE(c_int, c_void_p, POINTER(c_ubyte),
+_rint_voidp_ubytep_uintp = CFUNCTYPE(c_int, c_int, POINTER(c_ubyte),
                                      POINTER(c_uint))
-_rint_voidp_ubytep_uint = CFUNCTYPE(c_int, c_void_p, POINTER(c_ubyte), c_uint)
+_rint_voidp_ubytep_uint = CFUNCTYPE(c_int, c_int, POINTER(c_ubyte), c_uint)
 
 def SSL_CTX_set_cookie_cb(ctx, generate, verify):
     def py_generate_cookie_cb(ssl, cookie, cookie_len):

dtls/test/unit.py

@@ -154,10 +154,14 @@ class BasicSocketTests(unittest.TestCase):
         # something unexpected like TypeError.
         s = socket.socket(AF_INET4_6, socket.SOCK_DGRAM)
         ss = ssl.wrap_socket(s)
+        if os.name != "posix":
+            # On Linux, unconnected, unbound datagram sockets can receive and
+            # the following calls will therefore block
             self.assertRaises(socket.error, ss.recv, 1)
             self.assertRaises(socket.error, ss.recv_into, bytearray(b'x'))
             self.assertRaises(socket.error, ss.recvfrom, 1)
-        self.assertRaises(socket.error, ss.recvfrom_into, bytearray(b'x'), 1)
+            self.assertRaises(socket.error, ss.recvfrom_into, bytearray(b'x'),
+                              1)
         self.assertRaises(socket.error, ss.send, b'x')
         self.assertRaises(socket.error, ss.sendto, b'x',
                           ('0.0.0.0', 0) if AF_INET4_6 == socket.AF_INET else