Squashed 'external/toxcore/c-toxcore/' content from commit 67badf69

git-subtree-dir: external/toxcore/c-toxcore
git-subtree-split: 67badf69416a74e74f6d7eb51dd96f37282b8455

docs/updates/Spam-Prevention.md

@@ -0,0 +1,12 @@
+ 
+Situation 1:
+Someone randomly goes around the DHT sending friend requests to everyone.
+
+Prevented by:
+Every friend address: 
+[client_id (32 bytes)][nospam number (4 bytes)][checksum (2 bytes)] 
+contains a number (nospam).
+
+The nospam in every friend request to that friend must be that number.
+
+If not it is rejected.