Update dependencies and copyright year (#2436)

- aiohttp 3.5
- websockets 7
- Rapptz/discord.py@700dbb5
- A few others

Signed-off-by: Toby Harradine <tobyharradine@gmail.com>

discord/voice_client.py

@@ -3,7 +3,7 @@
 """
 The MIT License (MIT)
 
-Copyright (c) 2015-2017 Rapptz
+Copyright (c) 2015-2019 Rapptz
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),
@@ -105,6 +105,7 @@ class VoiceClient:
         self._connected = threading.Event()
         self._handshake_complete = asyncio.Event(loop=self.loop)
 
+        self.mode = None
         self._connections = 0
         self.sequence = 0
         self.timestamp = 0
@@ -113,6 +114,7 @@ class VoiceClient:
         self.encoder = opus.Encoder()
 
     warn_nacl = not has_nacl
+    supported_modes = ("xsalsa20_poly1305_suffix", "xsalsa20_poly1305")
 
     @property
     def guild(self):
@@ -305,22 +307,30 @@ class VoiceClient:
 
     def _get_voice_packet(self, data):
         header = bytearray(12)
-        nonce = bytearray(24)
-        box = nacl.secret.SecretBox(bytes(self.secret_key))
 
-        # Formulate header
+        # Formulate rtp header
         header[0] = 0x80
         header[1] = 0x78
         struct.pack_into(">H", header, 2, self.sequence)
         struct.pack_into(">I", header, 4, self.timestamp)
         struct.pack_into(">I", header, 8, self.ssrc)
 
-        # Copy header to nonce's first 12 bytes
+        encrypt_packet = getattr(self, "_encrypt_" + self.mode)
+        return encrypt_packet(header, data)
+
+    def _encrypt_xsalsa20_poly1305(self, header, data):
+        box = nacl.secret.SecretBox(bytes(self.secret_key))
+        nonce = bytearray(24)
         nonce[:12] = header
 
-        # Encrypt and return the data
         return header + box.encrypt(bytes(data), bytes(nonce)).ciphertext
 
+    def _encrypt_xsalsa20_poly1305_suffix(self, header, data):
+        box = nacl.secret.SecretBox(bytes(self.secret_key))
+        nonce = nacl.utils.random(nacl.secret.SecretBox.NONCE_SIZE)
+
+        return header + box.encrypt(bytes(data), nonce).ciphertext + nonce
+
     def play(self, source, *, after=None):
         """Plays an :class:`AudioSource`.