8 files changed, 474 insertions, 0 deletions
diff --git a/lib/app/chat.ex b/lib/app/chat.ex
new file mode 100644
index 0000000..4a56085
--- /dev/null
+++ b/lib/app/chat.ex
@@ -0,0 +1,21 @@
+defmodule SApp.Chat do
+  def send(msg) do
+    msgitem = {(System.os_time :seconds),
+               Shard.Identity.get_nickname(),
+               msg}
+    GenServer.cast(SApp.Chat.Log, {:insert, msgitem})
+
+    SNet.ConnSupervisor
+    |> DynamicSupervisor.which_children
+    |> Enum.each(fn {_, pid, _, _} -> GenServer.cast(pid, :init_push) end)
+  end
+
+  def msg_callback({ts, nick, msg}) do
+    IO.puts "#{ts |> DateTime.from_unix! |> DateTime.to_iso8601} <#{nick}> #{msg}"
+  end
+
+  def msg_cmp({ts1, nick1, msg1}, {ts2, nick2, msg2}) do
+    SData.MerkleList.cmp_ts_str({ts1, nick1<>"|"<>msg1}, 
+                                   {ts2, nick2<>"|"<>msg2})
+  end 
+end
diff --git a/lib/application.ex b/lib/application.ex
new file mode 100644
index 0000000..a199e6c
--- /dev/null
+++ b/lib/application.ex
@@ -0,0 +1,33 @@
+defmodule Shard.Application do
+  @moduledoc """
+  Documentation for Shard.
+  """
+
+  use Application
+
+  def start(_type, _args) do
+    import Supervisor.Spec, warn: false
+
+    {listen_port, _} = Integer.parse ((System.get_env "PORT") || "4044")
+
+    # Define workers and child supervisors to be supervised
+    children = [
+      Shard.Identity,
+      
+      # Networking
+      { DynamicSupervisor, strategy: :one_for_one, name: SNet.ConnSupervisor },
+      { SNet.TCPServer, listen_port },
+
+      # Applications & data store
+      { SData.MerkleList, [&SApp.Chat.msg_cmp/2, name: SApp.Chat.Log] },
+
+      # Web UI
+      Plug.Adapters.Cowboy.child_spec(:http, SWeb.HTTPRouter, [], port: listen_port + 1000)
+    ]
+
+    # See http://elixir-lang.org/docs/stable/elixir/Supervisor.html
+    # for other strategies and supported options
+    opts = [strategy: :one_for_one, name: Shard.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end
diff --git a/lib/cli/cli.ex b/lib/cli/cli.ex
new file mode 100644
index 0000000..4643351
--- /dev/null
+++ b/lib/cli/cli.ex
@@ -0,0 +1,30 @@
+defmodule SCLI do
+  def run() do
+    str = "say: " |> IO.gets |> String.trim
+    cond do
+      str == "/quit" ->
+        nil
+      String.slice(str, 0..0) == "/" ->
+        command = str |> String.slice(1..-1) |> String.split(" ")
+        handle_command(command)
+        run()
+      true -> 
+        SApp.Chat.send(str)
+        run()
+    end
+  end
+
+  def handle_command(["connect", ipstr, portstr]) do
+    {:ok, ip} = :inet.parse_address (to_charlist ipstr)
+    {port, _} = Integer.parse portstr
+    SNet.TCPServer.add_peer(ip, port)
+  end
+
+  def handle_command(["nick", nick]) do
+    Shard.Identity.set_nickname nick
+  end
+
+  def handle_command(_cmd) do
+    IO.puts "Invalid command"
+  end
+end
diff --git a/lib/data/merklelist.ex b/lib/data/merklelist.ex
new file mode 100644
index 0000000..c9e27f6
--- /dev/null
+++ b/lib/data/merklelist.ex
@@ -0,0 +1,136 @@
+defmodule SData.MerkleList do
+  use GenServer
+
+  def start_link([cmp, name: name]) do
+    GenServer.start_link(__MODULE__, cmp, [name: name])
+  end
+
+  defp term_hash(term) do
+    :crypto.hash(:sha256, (:erlang.term_to_binary term))
+  end
+
+  @doc """
+    Initialize a Merkle List storage.
+    `cmp` is a function that compares stored items and provides a total order.
+
+    It must return:
+      - `:after` if the first argument is more recent
+      - `:duplicate` if the two items are the same
+      - `:before` if the first argument is older
+  """
+  def init(cmp) do
+    root_item = :root
+    root_hash = term_hash root_item
+    state = %{
+              root:  root_hash,
+              top:   root_hash,
+              cmp:   cmp,
+              store: %{ root_hash => root_item }
+            }
+    {:ok, state}
+  end
+
+  defp state_push(item, state) do
+    new_item = {item, state.top}
+    new_item_hash = term_hash new_item
+    new_store = Map.put(state.store, new_item_hash, new_item)
+    %{ state | :top => new_item_hash, :store => new_store }
+  end
+
+  defp state_pop(state) do
+    if state.top == state.root do
+      :error
+    else
+      {item, next} = Map.get(state.store, state.top)
+      new_store = Map.delete(state.store, state.top)
+      new_state = %{ state | :top => next, :store => new_store }
+      {:ok, item, new_state}
+    end
+  end
+
+  defp insert_many(state, [], _callback) do
+    state
+  end
+
+  defp insert_many(state, [item | rest], callback) do
+    case state_pop(state) do
+      :error ->
+        new_state = state_push(item, insert_many(state, rest, callback))
+        callback.(item)
+        new_state
+      {:ok, front, state_rest} ->
+        case state.cmp.(item, front) do
+          :after ->
+            new_state = state_push(item, insert_many(state, rest, callback))
+            callback.(item)
+            new_state
+          :duplicate -> insert_many(state, rest, callback)
+          :before -> state_push(front, insert_many(state_rest, [item | rest], callback))
+        end
+    end
+  end
+
+  def handle_cast({:insert, item}, state) do
+    handle_cast({:insert_many, [item]}, state)
+  end
+
+  def handle_cast({:insert_many, items}, state) do
+    handle_cast({:insert_many, items, fn _ -> nil end}, state)
+  end
+
+  def handle_cast({:insert_many, items, callback}, state) do
+    items_sorted = Enum.sort(items, fn (x, y) -> state.cmp.(x, y) == :after end)
+    new_state = insert_many(state, items_sorted, callback)
+    {:noreply, new_state}
+  end
+
+  def handle_call({:read, qbegin, qlimit}, _from, state) do
+    begin = qbegin || state.top
+    limit = qlimit || 20
+    items = get_items_list(state, begin, limit)
+    {:reply, items, state}
+  end
+
+  def handle_call(:top, _from, state) do
+    {:reply, state.top, state}
+  end
+
+  def handle_call(:root, _from, state) do
+    {:reply, state.root, state}
+  end
+
+  def handle_call({:has, hash}, _from, state) do
+    {:reply, Map.has_key?(state.store, hash), state}
+  end
+
+  defp get_items_list(state, begin, limit) do
+    case limit do
+      0 -> {:ok, [], begin}
+      _ ->
+        case Map.fetch(state.store, begin) do
+          {:ok, :root} ->
+            {:ok, [], nil }
+          {:ok, {item, next}} ->
+            case get_items_list(state, next, limit - 1) do
+              {:ok, rest, past} ->
+                {:ok, [ item | rest ], past }
+              {:error, reason} -> {:error, reason}
+            end
+          :error -> {:error, begin}
+        end
+    end
+  end
+
+  @doc """
+    Compare function for timestamped strings
+  """
+  def cmp_ts_str({ts1, str1}, {ts2, str2}) do
+    cond do
+      ts1 > ts2 -> :after
+      ts1 < ts2 -> :before
+      str1 == str2 -> :duplicate
+      str1 > str2 -> :after
+      str1 < str2 -> :before
+    end
+  end
+end
diff --git a/lib/identity.ex b/lib/identity.ex
new file mode 100644
index 0000000..229d6c7
--- /dev/null
+++ b/lib/identity.ex
@@ -0,0 +1,32 @@
+defmodule Shard.Identity do
+  use Agent
+  require Salty.Sign.Ed25519, as: Sign
+
+  def start_link(_) do
+    Agent.start_link(__MODULE__, :init, [], name: __MODULE__)
+  end
+
+  def init() do
+    {:ok, pk, sk} = Sign.keypair
+    nick_suffix = pk
+                  |> binary_part(0, 3)
+                  |> Base.encode16
+                  |> String.downcase
+    %{
+      keypair:  {pk, sk},
+      nickname: "Anon" <> nick_suffix,
+    }
+  end
+
+  def get_keypair() do
+    Agent.get(__MODULE__, &(&1.keypair))
+  end
+
+  def get_nickname() do
+    Agent.get(__MODULE__, &(&1.nickname))
+  end
+
+  def set_nickname(newnick) do
+    Agent.update(__MODULE__, &(%{&1 | nickname: newnick}))
+  end
+end
diff --git a/lib/net/tcpconn.ex b/lib/net/tcpconn.ex
new file mode 100644
index 0000000..5d6c912
--- /dev/null
+++ b/lib/net/tcpconn.ex
@@ -0,0 +1,134 @@
+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
+    :gen_tcp.send(socket, srv_pkey <> sess_pkey <> challenge)  
+    {:ok, pkt} = :gen_tcp.recv(socket, 0)
+    cli_pkey = binary_part(pkt, 0, Sign.publickeybytes)
+    cli_sess_pkey = binary_part(pkt, Sign.publickeybytes, Box.publickeybytes)
+    cli_challenge = binary_part(pkt, Sign.publickeybytes + Box.publickeybytes, 32)
+
+    # 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
+      }
+    Logger.info "New peer: #{print_id state} at #{inspect addr}:#{port}"
+
+    GenServer.cast(self(), :init_push)
+
+    {:noreply, state}
+  end
+
+  def handle_cast({:send_msg, msg}, state) do
+    send_msg(state, msg)
+    {:noreply, state}
+  end
+
+  def handle_cast(:init_push, state) do
+    push_messages(state, nil, 10)
+    {: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}"
+    exit(:normal)
+  end
+
+  defp push_messages(state, start, num) do
+    case GenServer.call(SApp.Chat.Log, {:read, start, num}) do
+      {:ok, list, rest} ->
+        send_msg(state, {:info, start, list, rest})
+      _ -> nil
+    end
+  end
+
+  defp handle_packet(msg, state) do
+    # Logger.info "Message: #{inspect msg}"
+    case msg do
+      :get_top -> push_messages(state, nil, 10)
+      {:get, start} -> push_messages(state, start, 20)
+      {:info, _start, list, rest} ->
+        if rest != nil and not GenServer.call(SApp.Chat.Log, {:has, rest}) do
+          send_msg(state, {:get, rest})
+        end
+        spawn_link(fn ->
+          Process.sleep 1000
+          GenServer.cast(SApp.Chat.Log, {:insert_many, list, &SApp.Chat.msg_callback/1})
+        end)
+    end
+  end
+
+  defp print_id(state) do
+    state.his_pkey
+    |> binary_part(0, 8)
+    |> Base.encode16
+    |> String.downcase
+  end
+end
diff --git a/lib/net/tcpserver.ex b/lib/net/tcpserver.ex
new file mode 100644
index 0000000..e5ee996
--- /dev/null
+++ b/lib/net/tcpserver.ex
@@ -0,0 +1,35 @@
+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)
+  end
+
+  defp loop_acceptor(socket) do
+    {:ok, client} = :gen_tcp.accept(socket)
+    {:ok, pid} = DynamicSupervisor.start_child(SNet.ConnSupervisor, {SNet.TCPConn, %{socket: client}})
+    :ok = :gen_tcp.controlling_process(client, pid)
+    loop_acceptor(socket)
+  end
+
+  def add_peer(ip, port) do
+    {:ok, client} = :gen_tcp.connect(ip, port, [:binary, packet: 2, active: false])
+    {:ok, pid} = DynamicSupervisor.start_child(SNet.ConnSupervisor, {SNet.TCPConn, %{socket: client}})
+    :ok = :gen_tcp.controlling_process(client, pid)
+    pid
+  end
+
+end
+
diff --git a/lib/web/httprouter.ex b/lib/web/httprouter.ex
new file mode 100644
index 0000000..5027df4
--- /dev/null
+++ b/lib/web/httprouter.ex
@@ -0,0 +1,53 @@
+defmodule SWeb.HTTPRouter do
+  use Plug.Router
+  use Plug.ErrorHandler
+
+  plug Plug.Parsers, parsers: [:urlencoded, :multipart]
+
+  plug :match
+  plug :dispatch
+
+  get "/" do
+    main_page(conn)
+  end
+
+  post "/" do
+    if Map.has_key?(conn.params, "msg") do
+      SApp.Chat.send(conn.params["msg"])
+    end
+    if Map.has_key?(conn.params, "nick") do
+      Shard.Identity.set_nickname(conn.params["nick"])
+    end
+    if Map.has_key?(conn.params, "peer") do
+      [ipstr, portstr] = String.split(conn.params["peer"], ":")
+      {:ok, ip} = :inet.parse_address (to_charlist ipstr)
+      {port, _} = Integer.parse portstr
+      SNet.TCPServer.add_peer(ip, port)
+    end
+
+    main_page(conn)
+  end
+
+  match _ do
+    send_resp(conn, 404, "Oops!")
+  end
+
+  def main_page(conn) do
+    {:ok, messages, _} = GenServer.call(SApp.Chat.Log, {:read, nil, 42})
+
+    msgtxt = messages
+    |> Enum.map(fn {ts, nick, msg} -> "#{ts |> DateTime.from_unix! |> DateTime.to_iso8601} &lt;#{nick}&gt; #{msg}\n" end)
+
+    peerlist = SNet.ConnSupervisor
+    |> DynamicSupervisor.which_children
+    |> Enum.map(fn {_, pid, _, _} -> "#{GenServer.call(pid, :get_host_str)}\n" end)
+
+    conn
+    |> put_resp_content_type("text/html")
+    |> send_resp(200, "<pre>#{msgtxt}</pre>" <>
+                      "<form method=POST><input type=text name=msg /><input type=submit value=send /></form>" <>
+                      "<form method=POST><input type=text name=nick value=\"#{Shard.Identity.get_nickname}\" /><input type=submit value=\"change nick\" /></form>" <>
+                      "<hr/><pre>#{peerlist}</pre>" <>
+                      "<form method=POST><input type=text name=peer /><input type=submit value=\"add peer\" /></form>")
+  end
+end