refactor: use UeberauthOidcc as a library

lib/ueberauth/strategy/google.ex

@@ -6,21 +6,31 @@ defmodule Ueberauth.Strategy.Google do
   use Ueberauth.Strategy,
     uid_field: :sub,
     default_scope: "email",
-    hd: nil,
-    userinfo_endpoint: "https://www.googleapis.com/oauth2/v3/userinfo"
+    hd: nil
 
-  alias Ueberauth.Auth.Info
-  alias Ueberauth.Auth.Credentials
   alias Ueberauth.Auth.Extra
 
+  @session_key "ueberauth_strategy_google"
+
   @doc """
   Handles initial request for Google authentication.
   """
   def handle_request!(conn) do
-    scopes = conn.params["scope"] || option(conn, :default_scope)
-
-    params =
-      [scope: scopes]
+    scopes =
+      String.split(
+        conn.params["scope"] || option(conn, :default_scope),
+        " "
+      )
+
+    scopes =
+      if "openid" in scopes do
+        scopes
+      else
+        ["openid"] ++ scopes
+      end
+
+    authorization_params =
+      []
       |> with_optional(:hd, conn)
       |> with_optional(:prompt, conn)
       |> with_optional(:access_type, conn)
@@ -30,33 +40,39 @@ defmodule Ueberauth.Strategy.Google do
       |> with_param(:prompt, conn)
       |> with_param(:login_hint, conn)
       |> with_param(:hl, conn)
-      |> with_state_param(conn)
 
-    opts = oauth_client_options_from_conn(conn)
-    redirect!(conn, Ueberauth.Strategy.Google.OAuth.authorize_url!(params, opts))
+    opts =
+      conn
+      |> options_from_conn()
+      |> Map.put(:scopes, scopes)
+      |> Map.put(:authorization_params, Map.new(authorization_params))
+
+    case UeberauthOidcc.Request.handle_request(opts, conn) do
+      {:ok, conn} ->
+        conn
+
+      {:error, conn, reason} ->
+        UeberauthOidcc.Error.set_described_error(conn, reason, "error")
+    end
   end
 
   @doc """
   Handles the callback from Google.
   """
-  def handle_callback!(%Plug.Conn{params: %{"code" => code}} = conn) do
-    params = [code: code]
-    opts = oauth_client_options_from_conn(conn)
+  def handle_callback!(%Plug.Conn{} = conn) do
+    opts = options_from_conn(conn)
 
-    case Ueberauth.Strategy.Google.OAuth.get_access_token(params, opts) do
-      {:ok, token} ->
-        fetch_user(conn, token)
+    case UeberauthOidcc.Callback.handle_callback(opts, conn) do
+      {:ok, conn, token, userinfo} ->
+        conn
+        |> put_private(:google_token, token)
+        |> put_private(:google_user, userinfo)
 
-      {:error, {error_code, error_description}} ->
-        set_errors!(conn, [error(error_code, error_description)])
+      {:error, conn, reason} ->
+        UeberauthOidcc.Error.set_described_error(conn, reason, "error")
     end
   end
 
-  @doc false
-  def handle_callback!(conn) do
-    set_errors!(conn, [error("missing_code", "No code received")])
-  end
-
   @doc false
   def handle_cleanup!(conn) do
     conn
@@ -81,87 +97,49 @@ defmodule Ueberauth.Strategy.Google do
   """
   def credentials(conn) do
     token = conn.private.google_token
-    scope_string = token.other_params["scope"] || ""
-    scopes = String.split(scope_string, " ")
-
-    %Credentials{
-      expires: !!token.expires_at,
-      expires_at: token.expires_at,
-      scopes: scopes,
-      token_type: Map.get(token, :token_type),
-      refresh_token: token.refresh_token,
-      token: token.access_token
-    }
+    credentials = UeberauthOidcc.Auth.credentials(token)
+    %{credentials | other: %{}}
   end
 
   @doc """
   Fetches the fields to populate the info section of the `Ueberauth.Auth` struct.
   """
   def info(conn) do
+    token = conn.private.google_token
     user = conn.private.google_user
 
-    %Info{
-      email: user["email"],
-      first_name: user["given_name"],
-      image: user["picture"],
-      last_name: user["family_name"],
-      name: user["name"],
-      birthday: user["birthday"],
-      urls: %{
-        profile: user["profile"],
-        website: user["hd"]
-      }
+    info = UeberauthOidcc.Auth.info(token, user)
+
+    %{
+      info
+      | birthday: info.birthday || user["birthday"],
+        urls: Map.put_new(info.urls, :website, user["hd"])
     }
   end
 
   @doc """
   Stores the raw information (including the token) obtained from the google callback.
   """
   def extra(conn) do
+    creds = credentials(conn)
+
+    # create a struct with the same format as the old token, even if we don't depend on OAuth2
+    google_token = %{
+      __struct__: OAuth2.AccessToken,
+      access_token: creds.token,
+      refresh_token: creds.refresh_token,
+      expires_at: creds.expires_at,
+      token_type: "Bearer"
+    }
+
     %Extra{
       raw_info: %{
-        token: conn.private.google_token,
+        token: google_token,
         user: conn.private.google_user
       }
     }
   end
 
-  defp fetch_user(conn, token) do
-    conn = put_private(conn, :google_token, token)
-
-    # userinfo_endpoint from https://accounts.google.com/.well-known/openid-configuration
-    # the userinfo_endpoint may be overridden in options when necessary.
-    resp = Ueberauth.Strategy.Google.OAuth.get(token, get_userinfo_endpoint(conn))
-
-    case resp do
-      {:ok, %OAuth2.Response{status_code: 401, body: _body}} ->
-        set_errors!(conn, [error("token", "unauthorized")])
-
-      {:ok, %OAuth2.Response{status_code: status_code, body: user}}
-      when status_code in 200..399 ->
-        put_private(conn, :google_user, user)
-
-      {:error, %OAuth2.Response{status_code: status_code}} ->
-        set_errors!(conn, [error("OAuth2", status_code)])
-
-      {:error, %OAuth2.Error{reason: reason}} ->
-        set_errors!(conn, [error("OAuth2", reason)])
-    end
-  end
-
-  defp get_userinfo_endpoint(conn) do
-    case option(conn, :userinfo_endpoint) do
-      {:system, varname, default} ->
-        System.get_env(varname) || default
-
-      {:system, varname} ->
-        System.get_env(varname) || Keyword.get(default_options(), :userinfo_endpoint)
-
-      other ->
-        other
-    end
-  end
-
   defp with_param(opts, key, conn) do
     if value = conn.params[to_string(key)], do: Keyword.put(opts, key, value), else: opts
   end
@@ -170,18 +148,45 @@ defmodule Ueberauth.Strategy.Google do
     if option(conn, key), do: Keyword.put(opts, key, option(conn, key)), else: opts
   end
 
-  defp oauth_client_options_from_conn(conn) do
-    base_options = [redirect_uri: callback_url(conn)]
-    request_options = conn.private[:ueberauth_request_options].options
+  defp options_from_conn(conn) do
+    base_options = [
+      issuer: UeberauthGoogle.ProviderConfiguration,
+      userinfo: true,
+      session_key: @session_key
+    ]
 
-    case {request_options[:client_id], request_options[:client_secret]} do
-      {nil, _} -> base_options
-      {_, nil} -> base_options
-      {id, secret} -> [client_id: id, client_secret: secret] ++ base_options
-    end
+    request_options = conn.private[:ueberauth_request_options].options
+    oauth_options = Application.get_env(:ueberauth, Ueberauth.Strategy.Google.OAuth) || []
+
+    [
+      base_options,
+      request_options,
+      oauth_options
+    ]
+    |> UeberauthOidcc.Config.merge_and_expand_configuration()
+    |> generate_client_secret()
+    |> fix_token_url()
   end
 
   defp option(conn, key) do
     Keyword.get(options(conn), key, Keyword.get(default_options(), key))
   end
+
+  defp generate_client_secret(%{client_secret: {mod, fun}} = opts) do
+    Map.put(opts, :client_secret, apply(mod, fun, [Keyword.new(opts)]))
+  end
+
+  defp generate_client_secret(opts) do
+    opts
+  end
+
+  defp fix_token_url(%{token_url: token_endpoint} = opts) do
+    opts
+    |> Map.put(:token_endpoint, token_endpoint)
+    |> Map.delete(:token_url)
+  end
+
+  defp fix_token_url(opts) do
+    opts
+  end
 end

lib/ueberauth_google/application.ex

@@ -0,0 +1,19 @@
+defmodule UeberauthGoogle.Application do
+  @moduledoc false
+
+  use Application
+
+  @impl true
+  def start(_type, _args) do
+    children = [
+      {Oidcc.ProviderConfiguration.Worker,
+       %{
+         name: UeberauthGoogle.ProviderConfiguration,
+         issuer: "https://accounts.google.com"
+       }}
+    ]
+
+    opts = [strategy: :one_for_one, name: UeberauthGoogle.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end