defmodule Lokal.Accounts.UserToken do @moduledoc """ Schema for a user's session token """ use Ecto.Schema import Ecto.Query alias Ecto.{Association, UUID} alias Lokal.Accounts.User @hash_algorithm :sha256 @rand_size 32 # It is very important to keep the reset password token expiry short, # since someone with access to the email may take over the account. @reset_password_validity_in_days 1 @confirm_validity_in_days 7 @change_email_validity_in_days 7 @session_validity_in_days 60 @primary_key {:id, :binary_id, autogenerate: true} @foreign_key_type :binary_id schema "users_tokens" do field :token, :binary field :context, :string field :sent_to, :string belongs_to :user, User timestamps(updated_at: false) end @type t :: %__MODULE__{ id: id(), token: token(), context: String.t(), sent_to: String.t(), user: User.t() | Association.NotLoaded.t(), user_id: User.id() | nil, inserted_at: NaiveDateTime.t() } @type new_user_token :: %__MODULE__{} @type id :: UUID.t() @type token :: binary() @doc """ Generates a token that will be stored in a signed place, such as session or cookie. As they are signed, those tokens do not need to be hashed. """ def build_session_token(user) do token = :crypto.strong_rand_bytes(@rand_size) {token, %__MODULE__{token: token, context: "session", user_id: user.id}} end @doc """ Checks if the token is valid and returns its underlying lookup query. The query returns the user found by the token. """ def verify_session_token_query(token) do query = from token in token_and_context_query(token, "session"), join: user in assoc(token, :user), where: token.inserted_at > ago(@session_validity_in_days, "day"), select: user {:ok, query} end @doc """ Builds a token with a hashed counter part. The non-hashed token is sent to the user email while the hashed part is stored in the database, to avoid reconstruction. The token is valid for a week as long as users don't change their email. """ def build_email_token(user, context) do build_hashed_token(user, context, user.email) end defp build_hashed_token(user, context, sent_to) do token = :crypto.strong_rand_bytes(@rand_size) hashed_token = :crypto.hash(@hash_algorithm, token) {Base.url_encode64(token, padding: false), %__MODULE__{ token: hashed_token, context: context, sent_to: sent_to, user_id: user.id }} end @doc """ Checks if the token is valid and returns its underlying lookup query. The query returns the user found by the token. """ def verify_email_token_query(token, context) do case Base.url_decode64(token, padding: false) do {:ok, decoded_token} -> hashed_token = :crypto.hash(@hash_algorithm, decoded_token) days = days_for_context(context) query = from token in token_and_context_query(hashed_token, context), join: user in assoc(token, :user), where: token.inserted_at > ago(^days, "day") and token.sent_to == user.email, select: user {:ok, query} :error -> :error end end defp days_for_context("confirm"), do: @confirm_validity_in_days defp days_for_context("reset_password"), do: @reset_password_validity_in_days @doc """ Checks if the token is valid and returns its underlying lookup query. The query returns the user token record. """ def verify_change_email_token_query(token, context) do case Base.url_decode64(token, padding: false) do {:ok, decoded_token} -> hashed_token = :crypto.hash(@hash_algorithm, decoded_token) query = from token in token_and_context_query(hashed_token, context), where: token.inserted_at > ago(@change_email_validity_in_days, "day") {:ok, query} :error -> :error end end @doc """ Returns the given token with the given context. """ def token_and_context_query(token, context) do from __MODULE__, where: [token: ^token, context: ^context] end @doc """ Gets all tokens for the given user for the given contexts. """ def user_and_contexts_query(user, :all) do from t in __MODULE__, where: t.user_id == ^user.id end def user_and_contexts_query(user, [_ | _] = contexts) do from t in __MODULE__, where: t.user_id == ^user.id and t.context in ^contexts end end