talklittle / guardian_db

Guardian DB integration for tracking tokens and ensuring logout cannot be replayed.

GuardianDb

GuardianDB is an extension to vanilla Guardian that tracks tokens in your application to prevent playback.

All tokens are stored in the database when initially generated. After that, each time they are verified, the token is looked up. If present, the verification continues but if it is not found, the verification is abandoned with an error response.

    case Guardian.encode_and_sign(resource, type, claims) do
      { :ok, jwt, full_claims } -> # cool
      { :error, :token_storage_failure } -> # this comes from GuardianDb
      { :error, reason } -> # handle failure
    end

    case Guardian.decode_and_verify(jwt) do
      { :ok, claims } -> # stuff with the claims
      { :error, :token_not_found } -> # This comes from GuardianDb
      { :error, reason } -> # something else stopped us from verifying
    end

When you want to revoke a token, call Guardian.revoke!. This is called automatically by Guardian when using the sign_out function. But for times when you're using an API.

    case Guardian.revoke! jwt, claims do
      :ok -> # Great
      { :error, :could_not_revoke_token } -> # Oh no GuardianDb
      { :error, reason } -> # Oh no
    end

To use GuardianDb you'll need to add a migration

    defmodule MyApp.Repo.Migrations.GuardianDb do
      use Ecto.Migration

      def up do
        create table(:guardian_tokens, primary_key: false) do
          add :jti, :string, primary_key: true
          add :typ, :string
          add :aud, :string
          add :iss, :string
          add :sub, :string
          add :exp, :bigint
          add :jwt, :text
          add :claims, :map
          timestamps
        end
        create unique_index(:guardian_tokens, [:jti, :aud])
      end

      def down do
        drop table(:guardian_tokens)
      end
    end

Add this to your configuration:

    config :guardian, Guardian,
           hooks: GuardianDb,
           #…

    config :guardian_db, GuardianDb,
           repo: MyApp.Repo,
           schema_name: "tokens" # Optional, default is "guardian_tokens"

It's a good idea to purge out any stale tokens that have already expired.

    GuardianDb.Token.purge_expired_tokens!

You can setup automatic purging by adding the GuardianDb.ExpiredSweeper as a worker to your supervision tree.

  worker(GuardianDb.ExpiredSweeper, [])

To configure your sweeper add a sweep_interval in minutes to your guardian_db config.

    config :guardian_db, GuardianDb,
           repo: MyApp.Repo,
           sweep_interval: 120 # 120 minutes

By default GuardianDb will not purge your expired tokens.