Merge pull request #2 from Simponic/erlang_ssh_server

Erlang ssh server #2

.gitignore

@@ -24,3 +24,5 @@ server-*.tar
 
 # Temporary files, for example, from tests.
 /tmp/
+
+.env

config/test.exs

@@ -1,11 +1,11 @@
 import Config
 
 config :chessh, RateLimits,
-  jail_timeout_ms: 5000,
+  jail_timeout_ms: 10_000,
   jail_attempt_threshold: 3
 
 config :chessh, Chessh.Repo,
-  database: "chessh-test",
+  database: "chesshtest",
   username: "postgres",
   password: "postgres",
   hostname: "localhost",

lib/chessh/auth/keys.ex

@@ -1,7 +1,16 @@
 defmodule Chessh.Auth.KeyAuthenticator do
-  alias Chessh.{Key, Repo}
+  alias Chessh.{Key, Repo, Player}
   import Ecto.Query
 
+  def authenticate(player = %Player{}, public_key) do
+    !!Repo.one(
+      from(k in Key,
+        where: k.key == ^Key.encode_key(public_key),
+        where: k.player_id == ^player.id
+      )
+    )
+  end
+
   def authenticate(username, public_key) do
     !!Repo.one(
       from(k in Key,

lib/chessh/auth/password.ex

@@ -1,9 +1,13 @@
 defmodule Chessh.Auth.PasswordAuthenticator do
   alias Chessh.{Player, Repo}
 
+  def authenticate(player = %Player{}, password) do
+    Player.valid_password?(player, password)
+  end
+
   def authenticate(username, password) do
     case Repo.get_by(Player, username: username) do
-      x -> Player.valid_password?(x, password)
+      player -> authenticate(player, password)
     end
   end
 end

lib/chessh/schema/node.ex

@@ -5,7 +5,7 @@ defmodule Chessh.Node do
 
   @primary_key {:id, :string, []}
   schema "nodes" do
-    field(:last_start, :utc_datetime)
+    field(:last_start, :utc_datetime_usec)
   end
 
   def changeset(node, attrs) do
@@ -18,7 +18,7 @@ defmodule Chessh.Node do
       nil -> %Chessh.Node{id: node_id}
       node -> node
     end
-    |> Chessh.Node.changeset(%{last_start: DateTime.utc_now()})
+    |> changeset(%{last_start: DateTime.utc_now()})
     |> Repo.insert_or_update()
   end
 end

lib/chessh/schema/player.ex

@@ -9,11 +9,18 @@ defmodule Chessh.Player do
     field(:password, :string, virtual: true)
     field(:hashed_password, :string)
 
+    field(:authentications, :integer, default: 0)
+
     has_many(:keys, Chessh.Key)
 
     timestamps()
   end
 
+  def authentications_changeset(player, attrs) do
+    player
+    |> cast(attrs, [:authentications])
+  end
+
   def registration_changeset(player, attrs, opts \\ []) do
     player
     |> cast(attrs, [:username, :password])

lib/chessh/schema/player_session.ex

@@ -1,10 +1,12 @@
 defmodule Chessh.PlayerSession do
-  alias Chessh.Repo
+  alias Chessh.{Repo, Player, PlayerSession, Utils}
   use Ecto.Schema
   import Ecto.{Query, Changeset}
+  require Logger
 
   schema "player_sessions" do
-    field(:login, :utc_datetime)
+    field(:process, :string)
+    field(:login, :utc_datetime_usec)
 
     belongs_to(:node, Chessh.Node, type: :string)
     belongs_to(:player, Chessh.Player)
@@ -17,7 +19,7 @@ defmodule Chessh.PlayerSession do
 
   def concurrent_sessions(player) do
     Repo.aggregate(
-      from(p in Chessh.PlayerSession,
+      from(p in PlayerSession,
         where: p.player_id == ^player.id
       ),
       :count
@@ -31,4 +33,48 @@ defmodule Chessh.PlayerSession do
       )
     )
   end
+
+  def player_within_concurrent_sessions_and_satisfies(username, auth_fn) do
+    max_sessions =
+      Application.get_env(:chessh, RateLimits)
+      |> Keyword.get(:max_concurrent_user_sessions)
+
+    Repo.transaction(fn ->
+      case Repo.one(
+             from(p in Player,
+               where: p.username == ^String.Chars.to_string(username),
+               lock: "FOR UPDATE"
+             )
+           ) do
+        nil ->
+          Logger.error("Player with username #{username} does not exist")
+          send(self(), {:authed, false})
+
+        player ->
+          authed =
+            auth_fn.(player) &&
+              PlayerSession.concurrent_sessions(player) < max_sessions
+
+          Repo.insert(%PlayerSession{
+            login: DateTime.utc_now(),
+            node_id: System.fetch_env!("NODE_ID"),
+            player: player,
+            # TODO: This PID may be wrong - need to determine if this PID is shared with disconnectfun
+            process: Utils.pid_to_str(self())
+          })
+
+          player
+          |> Player.authentications_changeset(%{authentications: player.authentications + 1})
+          |> Repo.update()
+
+          send(self(), {:authed, authed})
+      end
+    end)
+
+    receive do
+      {:authed, authed} -> authed
+    after
+      3_000 -> false
+    end
+  end
 end

lib/chessh/ssh/cli.ex

@@ -0,0 +1,26 @@
+defmodule Chessh.SSH.Cli do
+  @behaviour :ssh_server_channel
+
+  def init(_args) do
+    {:ok, %{}}
+  end
+
+  def handle_msg(_message, state) do
+    {:ok, state}
+  end
+
+  def handle_ssh_msg(
+        {:ssh_cm, _connection_handler, {:exit_signal, channel_id, _signal, _err, _lang}},
+        state
+      ) do
+    {:stop, channel_id, state}
+  end
+
+  def handle_ssh_msg(_message, state) do
+    {:ok, state}
+  end
+
+  def terminate(_reason, _state) do
+    :ok
+  end
+end

lib/chessh/ssh/daemon.ex

@@ -1,6 +1,10 @@
 defmodule Chessh.SSH.Daemon do
+  alias Chessh.{Repo, PlayerSession, Utils}
   alias Chessh.Auth.PasswordAuthenticator
   use GenServer
+  import Ecto.Query
+
+  require Logger
 
   def start_link(_) do
     GenServer.start_link(__MODULE__, %{
@@ -13,26 +17,19 @@ defmodule Chessh.SSH.Daemon do
     {:ok, state}
   end
 
-  def pwd_authenticate(username, password) do
+  def pwd_authenticate(username, password, {ip, _port}) do
-    # TODO - check concurrent sessions
-    PasswordAuthenticator.authenticate(
-      String.Chars.to_string(username),
-      String.Chars.to_string(password)
-    )
-  end
-
-  def pwd_authenticate(username, password, inet) do
     [jail_timeout_ms, jail_attempt_threshold] =
       Application.get_env(:chessh, RateLimits)
       |> Keyword.take([:jail_timeout_ms, :jail_attempt_threshold])
       |> Keyword.values()
 
-    {ip, _port} = inet
     rateId = "failed_password_attempts:#{Enum.join(Tuple.to_list(ip), ".")}"
 
-    if pwd_authenticate(username, password) do
+    case PasswordAuthenticator.authenticate(
-      true
+           String.Chars.to_string(username),
-    else
+           String.Chars.to_string(password)
+         ) do
+      false ->
         case Hammer.check_rate_inc(rateId, jail_timeout_ms, jail_attempt_threshold, 1) do
           {:allow, _count} ->
             false
@@ -40,6 +37,13 @@ defmodule Chessh.SSH.Daemon do
           {:deny, _limit} ->
             :disconnect
         end
+
+      x ->
+        if PlayerSession.player_within_concurrent_sessions_and_satisfies(username, fn _player ->
+             x
+           end),
+           do: true,
+           else: :disconnect
     end
   end
 
@@ -53,10 +57,13 @@ defmodule Chessh.SSH.Daemon do
 
     case :ssh.daemon(
            port,
+           # shell: fn _username, _peer -> Process.sleep(5000) end,
            system_dir: key_dir,
            pwdfun: &pwd_authenticate/4,
            key_cb: Chessh.SSH.ServerKey,
-           #          disconnectfun: 
+           ssh_cli: {Chessh.SSH.Cli, []},
+           #           connectfun: &on_connect/3,
+           disconnectfun: &on_disconnect/1,
            id_string: :random,
            subsystems: [],
            parallel_login: true,
@@ -74,4 +81,32 @@ defmodule Chessh.SSH.Daemon do
   end
 
   def handle_info(_, state), do: {:noreply, state}
+
+  #  defp on_connect(username, _inet, _method) do
+  #    Logger.debug("#{inspect(self())} connected and is authenticated as #{username}")
+  #
+  #    case Repo.get_by(Player, username: String.Chars.to_string(username)) do
+  #      nil ->
+  #        nil
+  #
+  #      player ->
+  #        Repo.insert(%PlayerSession{
+  #          login: DateTime.utc_now(),
+  #          node_id: System.fetch_env!("NODE_ID"),
+  #          player: player,
+  #          process: pid_to_str(self())
+  #        })
+  #    end
+  #  end
+
+  defp on_disconnect(_reason) do
+    Logger.debug("#{inspect(self())} disconnected")
+
+    Repo.delete_all(
+      from(p in PlayerSession,
+        where: p.node_id == ^System.fetch_env!("NODE_ID"),
+        where: p.process == ^Utils.pid_to_str(self())
+      )
+    )
+  end
 end

lib/chessh/ssh/server_key.ex

@@ -1,9 +1,14 @@
 defmodule Chessh.SSH.ServerKey do
+  alias Chessh.PlayerSession
   alias Chessh.Auth.KeyAuthenticator
+
   @behaviour :ssh_server_key_api
 
   def is_auth_key(key, username, _daemon_options) do
-    KeyAuthenticator.authenticate(username, key)
+    PlayerSession.player_within_concurrent_sessions_and_satisfies(
+      username,
+      &KeyAuthenticator.authenticate(&1, key)
+    )
   end
 
   def host_key(algorithm, daemon_options) do

lib/chessh/utils.ex

@@ -0,0 +1,9 @@
+defmodule Chessh.Utils do
+  def pid_to_str(pid) do
+    pid
+    |> :erlang.pid_to_list()
+    |> List.delete_at(0)
+    |> List.delete_at(-1)
+    |> to_string()
+  end
+end

priv/repo/migrations/20221229225556_add_node.exs

@@ -4,7 +4,7 @@ defmodule Chessh.Repo.Migrations.AddNode do
   def change do
     create table(:nodes, primary_key: false) do
       add(:id, :string, primary_key: true)
-      add(:last_start, :utc_datetime)
+      add(:last_start, :utc_datetime_usec)
     end
   end
 end

priv/repo/migrations/20221229225559_add_user_session.exs

@@ -3,9 +3,13 @@ defmodule Chessh.Repo.Migrations.AddUserSession do
 
   def change do
     create table(:player_sessions) do
-      add(:login, :utc_datetime)
+      add(:process, :string)
+      add(:login, :utc_datetime_usec)
+
       add(:player_id, references(:players))
       add(:node_id, references(:nodes, type: :string))
     end
+
+    create(unique_index(:player_sessions, [:process, :node_id]))
   end
 end

priv/repo/migrations/20221230102253_add_authenticating_column_to_player.exs

@@ -0,0 +1,9 @@
+defmodule Chessh.Repo.Migrations.AddAuthenticatingColumnToPlayer do
+  use Ecto.Migration
+
+  def change do
+    alter table(:players) do
+      add(:authentications, :integer, default: 0)
+    end
+  end
+end

test/auth/password_test.exs

@@ -8,7 +8,7 @@ defmodule Chessh.Auth.PasswordAuthenticatorTest do
     Ecto.Adapters.SQL.Sandbox.checkout(Repo)
     Ecto.Adapters.SQL.Sandbox.mode(Repo, {:shared, self()})
 
-    {:ok, _user} = Repo.insert(Player.registration_changeset(%Player{}, @valid_user))
+    {:ok, _player} = Repo.insert(Player.registration_changeset(%Player{}, @valid_user))
 
     :ok
   end
@@ -24,4 +24,13 @@ defmodule Chessh.Auth.PasswordAuthenticatorTest do
              "a_bad_password"
            )
   end
+
+  test "Password can authenticate a user instance" do
+    player = Repo.get_by(Player, username: "logan")
+
+    assert Chessh.Auth.PasswordAuthenticator.authenticate(
+             player,
+             @valid_user.password
+           )
+  end
 end

test/ssh/ssh_auth_test.exs

@@ -1,6 +1,6 @@
 defmodule Chessh.SSH.AuthTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: false
-  alias Chessh.{Player, Repo, Key}
+  alias(Chessh.{Player, Repo, Key, PlayerSession})
 
   @localhost '127.0.0.1'
   @localhost_inet {{127, 0, 0, 1}, 1}
@@ -26,6 +26,14 @@ defmodule Chessh.SSH.AuthTest do
     :ok
   end
 
+  def cleanup() do
+    Process.sleep(1_000)
+    PlayerSession.delete_all_on_node(System.fetch_env!("NODE_ID"))
+
+    # Wait for (what I believe to be the) DB Connection queue to clear?
+    Process.sleep(1_000)
+  end
+
   test "Password attempts are rate limited" do
     jail_attempt_threshold =
       Application.get_env(:chessh, RateLimits)
@@ -49,7 +57,7 @@ defmodule Chessh.SSH.AuthTest do
     test_pid = self()
 
     Task.Supervisor.start_child(sup, fn ->
-      {:ok, _pid} =
+      {:ok, conn} =
         :ssh.connect(@localhost, Application.fetch_env!(:chessh, :port),
           user: String.to_charlist(@valid_user.username),
           password: String.to_charlist(@valid_user.password),
@@ -57,11 +65,12 @@ defmodule Chessh.SSH.AuthTest do
           silently_accept_hosts: true
         )
 
+      :ssh.close(conn)
       send(test_pid, :connected_via_password)
     end)
 
     Task.Supervisor.start_child(sup, fn ->
-      {:ok, _pid} =
+      {:ok, conn} =
         :ssh.connect(@localhost, Application.fetch_env!(:chessh, :port),
           user: String.to_charlist(@valid_user.username),
           auth_methods: 'publickey',
@@ -69,15 +78,61 @@ defmodule Chessh.SSH.AuthTest do
           user_dir: String.to_charlist(@client_test_keys_dir)
         )
 
+      :ssh.close(conn)
       send(test_pid, :connected_via_public_key)
     end)
 
-    assert_receive(:connected_via_password, 500)
+    assert_receive(:connected_via_password, 2_000)
-    assert_receive(:connected_via_public_key, 500)
+    assert_receive(:connected_via_public_key, 2_000)
+
+    cleanup()
   end
 
-  # TODO
+  test "INTEGRATION - Player cannot have more than specified concurrent sessions" do
-  #  test "INTEGRATION - User cannot have more than specified concurrent sessions" do
+    max_concurrent_user_sessions =
-  #    :ok
+      Application.get_env(:chessh, RateLimits)
-  #  end
+      |> Keyword.get(:max_concurrent_user_sessions)
+
+    player = Repo.get_by(Player, username: @valid_user.username)
+
+    {:ok, sup} = Task.Supervisor.start_link()
+    test_pid = self()
+
+    Enum.reduce(0..(max_concurrent_user_sessions + 1), fn i, _ ->
+      Task.Supervisor.start_child(sup, fn ->
+        case :ssh.connect(@localhost, Application.fetch_env!(:chessh, :port),
+               user: String.to_charlist(@valid_user.username),
+               password: String.to_charlist(@valid_user.password),
+               auth_methods: if(rem(i, 2) == 0, do: 'publickey', else: 'password'),
+               silently_accept_hosts: true,
+               user_dir: String.to_charlist(@client_test_keys_dir)
+             ) do
+          {:ok, conn} ->
+            send(
+              test_pid,
+              {:attempted, {:ok, conn}}
+            )
+
+          x ->
+            send(test_pid, {:attempted, x})
+        end
+      end)
+    end)
+
+    Enum.reduce(0..max_concurrent_user_sessions, fn _, _ ->
+      assert_receive({:attempted, {:ok, _conn}}, 2000)
+    end)
+
+    assert_receive(
+      {:attempted, {:error, 'Unable to connect using the available authentication methods'}},
+      2000
+    )
+
+    # Give it time to send back the disconnection payload after session was opened
+    # but over threshold
+    :timer.sleep(100)
+    assert PlayerSession.concurrent_sessions(player) == max_concurrent_user_sessions
+
+    cleanup()
+  end
 end

test/test_helper.exs

@@ -1,3 +1,2 @@
 ExUnit.start()
-
 Ecto.Adapters.SQL.Sandbox.mode(Chessh.Repo, :manual)