1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
defmodule SNet.TCPConn do
use GenServer, restart: :temporary
require Salty.Box.Curve25519xchacha20poly1305, as: Box
require Salty.Sign.Ed25519, as: Sign
require Logger
def start_link(state) do
GenServer.start_link(__MODULE__, state)
end
def init(state) do
GenServer.cast(self(), :handshake)
{:ok, state}
end
def handle_call(:get_host_str, _from, state) do
{:reply, "#{state.his_pkey|>Base.encode16|>String.downcase}@#{to_string(:inet_parse.ntoa(state.addr))}:#{state.port}", state}
end
def handle_cast(:handshake, state) do
socket = state.socket
{srv_pkey, srv_skey} = Shard.Identity.get_keypair
{:ok, sess_pkey, sess_skey} = Box.keypair
{:ok, challenge} = Salty.Random.buf 32
# Exchange public keys and challenge
hello = {srv_pkey, sess_pkey, challenge, state.my_port}
:gen_tcp.send(socket, :erlang.term_to_binary hello)
{:ok, pkt} = :gen_tcp.recv(socket, 0)
{cli_pkey, cli_sess_pkey, cli_challenge, his_port} = :erlang.binary_to_term(pkt, [:safe])
# Do challenge and check their challenge
{:ok, cli_challenge_sign} = Sign.sign_detached(cli_challenge, srv_skey)
pkt = encode_pkt(cli_challenge_sign, cli_sess_pkey, sess_skey)
:gen_tcp.send(socket, pkt)
{:ok, pkt} = :gen_tcp.recv(socket, 0)
challenge_sign = decode_pkt(pkt, cli_sess_pkey, sess_skey)
:ok = Sign.verify_detached(challenge_sign, challenge, cli_pkey)
# Connected
:inet.setopts(socket, [active: true])
{:ok, {addr, port}} = :inet.peername socket
state =%{ socket: socket,
my_pkey: srv_pkey,
my_skey: srv_skey,
his_pkey: cli_pkey,
conn_my_pkey: sess_pkey,
conn_my_skey: sess_skey,
conn_his_pkey: cli_sess_pkey,
addr: addr,
port: port
}
GenServer.cast(SNet.Manager, {:peer_up, cli_pkey, self(), addr, his_port})
Logger.info "New peer: #{print_id state} at #{inspect addr}:#{port}"
GenServer.cast(self(), :init_pull)
{:noreply, state}
end
def handle_cast({:send_msg, msg}, state) do
send_msg(state, msg)
{:noreply, state}
end
def handle_cast(:init_pull, state) do
id_list = (for {id, _} <- GenServer.call(Shard.Manager, :list), do: id)
send_msg(state, {:interested, id_list})
{:noreply, state}
end
defp encode_pkt(pkt, pk, sk) do
{:ok, n} = Salty.Random.buf Box.noncebytes
{:ok, msg} = Box.easy(pkt, n, pk, sk)
n <> msg
end
defp decode_pkt(pkt, pk, sk) do
n = binary_part(pkt, 0, Box.noncebytes)
enc = binary_part(pkt, Box.noncebytes, (byte_size pkt) - Box.noncebytes)
{:ok, msg} = Box.open_easy(enc, n, pk, sk)
msg
end
defp send_msg(state, msg) do
msgbin = :erlang.term_to_binary msg
enc = encode_pkt(msgbin, state.conn_his_pkey, state.conn_my_skey)
:gen_tcp.send(state.socket, enc)
end
def handle_info({:tcp, _socket, raw_data}, state) do
msg = decode_pkt(raw_data, state.conn_his_pkey, state.conn_my_skey)
handle_packet(:erlang.binary_to_term(msg, [:safe]), state)
{:noreply, state}
end
def handle_info({:tcp_closed, _socket}, state) do
Logger.info "Disconnected: #{print_id state} at #{inspect state.addr}:#{state.port}"
GenServer.cast(SNet.Manager, {:peer_down, state.his_pkey, state.addr, state.port})
exit(:normal)
end
defp handle_packet({:interested, shards}, state) do
GenServer.cast(Shard.Manager, {:interested, state.his_pkey, self(), shards})
end
defp handle_packet({shard, msg}, state) do
GenServer.cast(Shard.Manager, {:dispatch, state.his_pkey, self(), shard, msg})
end
defp print_id(state) do
state.his_pkey
|> binary_part(0, 8)
|> Base.encode16
|> String.downcase
end
end
|
