Friends must now send to themselves at least one encrypted ping packet
every 5 seconds.
If no encrypted ping packets are recieved from a friend within 10
seconds the connection is killed.
Crypto requests packets are packets that can be routed by nodes in the
DHT. In this pull request I have merged both Natping requests and friend
requests into one common packet (Crypto request packets). Both these
packets should now only be distinguishable by the size of the data in
them to an outside observer for an example on how to send and recieve
data with these packets see: friend_requests.c
Note that these packets are prefixed with id 32 (friend request packets)
which means this change is compatible with the currently running DHT
bootstrap servers.
Also changed small thing in DHT_test.c
The friend address is what the byte string that you give away for people
to add you will be called.
1. Every friend address now contains a number set by the friend. This is
to prevent someone from randomly spamming people in the DHT with friend
requests and makes it so you need the person to actually give you the
address in some way to send the friend request. This number is expected
to be encrypted with the friend request. All requests that do not
contain this number will be rejected. This means the spammer can no
longer use the DHT to collect lists of valid addresses to spam. It also
enables users to quickly change the number in case a spammer gets hold
of the address and starts spamming it.
2. A 2 byte checksum will be added (not implemented yet) to prevent
people from accidentally adding random strings as friends. (NOTE that
this has nothing to do with the spam problem I just decided to add a
placeholder for it now.)
