2 files changed, 132 insertions, 0 deletions
diff --git a/shard/lib/net/tcpconn.ex b/shard/lib/net/tcpconn.ex
new file mode 100644
index 0000000..44669bb
--- /dev/null
+++ b/shard/lib/net/tcpconn.ex
@@ -0,0 +1,106 @@
+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)
+
+    expected_suffix = Application.get_env(:shard, :peer_id_suffix)
+    len = byte_size(expected_suffix)
+    ^len = :binary.longest_common_suffix([cli_pkey, expected_suffix])
+
+    # 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,
+        his_port: his_port
+      }
+    GenServer.cast(Shard.Manager, {:peer_up, cli_pkey, self(), addr, his_port})
+    Logger.info "New peer: #{print_id state} at #{inspect addr}:#{port}"
+
+    {:noreply, state}
+  end
+
+  def handle_cast({:send_msg, msg}, state) 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)
+    {: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
+
+  def handle_info({:tcp, _socket, raw_data}, state) do
+    msg = decode_pkt(raw_data, state.conn_his_pkey, state.conn_my_skey)
+    msg_data = :erlang.binary_to_term(msg, [:safe])
+    Shard.Manager.dispatch(state.his_pkey, msg_data)
+    {: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(Shard.Manager, {:peer_down, state.his_pkey, state.addr, state.his_port})
+    exit(:normal)
+  end
+
+  defp print_id(state) do
+    state.his_pkey
+    |> binary_part(0, 8)
+    |> Base.encode16
+    |> String.downcase
+  end
+end
diff --git a/shard/lib/net/tcpserver.ex b/shard/lib/net/tcpserver.ex
new file mode 100644
index 0000000..46552a4
--- /dev/null
+++ b/shard/lib/net/tcpserver.ex
@@ -0,0 +1,26 @@
+defmodule SNet.TCPServer do
+  require Logger
+  use Task, restart: :permanent
+
+  def start_link(port) do
+    Task.start_link(__MODULE__, :accept, [port])
+  end
+
+  @doc """
+  Starts accepting connections on the given `port`.
+  """
+  def accept(port) do
+    {:ok, socket} = :gen_tcp.listen(port,
+                      [:binary, packet: 2, active: false, reuseaddr: true])
+    Logger.info "Accepting connections on port #{port}"
+    loop_acceptor(socket, port)
+  end
+
+  defp loop_acceptor(socket, my_port) do
+    {:ok, client} = :gen_tcp.accept(socket)
+    {:ok, pid} = DynamicSupervisor.start_child(Shard.DynamicSupervisor, {SNet.TCPConn, %{socket: client, my_port: my_port}})
+    :ok = :gen_tcp.controlling_process(client, pid)
+    loop_acceptor(socket, my_port)
+  end
+end
+