allow synchronizing user status from OAuth2 login providers (#31572)

This leverages the existing `sync_external_users` cron job to
synchronize the `IsActive` flag on users who use an OAuth2 provider set
to synchronize. This synchronization is done by checking for expired
access tokens, and using the stored refresh token to request a new
access token. If the response back from the OAuth2 provider is the
`invalid_grant` error code, the user is marked as inactive. However, the
user is able to reactivate their account by logging in the web browser
through their OAuth2 flow.

Also changed to support this is that a linked `ExternalLoginUser` is
always created upon a login or signup via OAuth2.

Ideally, we would also refresh permissions from the configured OAuth
provider (e.g., admin, restricted and group mappings) to match the
implementation of LDAP. However, the OAuth library used for this `goth`,
doesn't seem to support issuing a session via refresh tokens. The
interface provides a [`RefreshToken`
method](https://github.com/markbates/goth/blob/master/provider.go#L20),
but the returned `oauth.Token` doesn't implement the `goth.Session` we
would need to call `FetchUser`. Due to specific implementations, we
would need to build a compatibility function for every provider, since
they cast to concrete types (e.g.
[Azure](https://github.com/markbates/goth/blob/master/providers/azureadv2/azureadv2.go#L132))

---------

Co-authored-by: Kyle D <kdumontnu@gmail.com>
(cherry picked from commit 416c36f3034e228a27258b5a8a15eec4e5e426ba)

Conflicts:
	- tests/integration/auth_ldap_test.go
	  Trivial conflict resolved by manually applying the change.
	- routers/web/auth/oauth.go
	  Technically not a conflict, but the original PR removed the
	  modules/util import, which in our version, is still in use. Added it
	  back.

models/auth/source.go

@@ -216,7 +216,7 @@ func CreateSource(ctx context.Context, source *Source) error {
 		return ErrSourceAlreadyExist{source.Name}
 	}
 	// Synchronization is only available with LDAP for now
-	if !source.IsLDAP() {
+	if !source.IsLDAP() && !source.IsOAuth2() {
 		source.IsSyncEnabled = false
 	}
 

models/user/external_login_user.go

@@ -160,12 +160,34 @@ func UpdateExternalUserByExternalID(ctx context.Context, external *ExternalLogin
 	return err
 }
 
+// EnsureLinkExternalToUser link the external user to the user
+func EnsureLinkExternalToUser(ctx context.Context, external *ExternalLoginUser) error {
+	has, err := db.Exist[ExternalLoginUser](ctx, builder.Eq{
+		"external_id":     external.ExternalID,
+		"login_source_id": external.LoginSourceID,
+	})
+	if err != nil {
+		return err
+	}
+
+	if has {
+		_, err = db.GetEngine(ctx).Where("external_id=? AND login_source_id=?", external.ExternalID, external.LoginSourceID).AllCols().Update(external)
+		return err
+	}
+
+	_, err = db.GetEngine(ctx).Insert(external)
+	return err
+}
+
 // FindExternalUserOptions represents an options to find external users
 type FindExternalUserOptions struct {
 	db.ListOptions
-	Provider string
-	UserID   int64
-	OrderBy  string
+	Provider        string
+	UserID          int64
+	LoginSourceID   int64
+	HasRefreshToken bool
+	Expired         bool
+	OrderBy         string
 }
 
 func (opts FindExternalUserOptions) ToConds() builder.Cond {
@@ -176,9 +198,22 @@ func (opts FindExternalUserOptions) ToConds() builder.Cond {
 	if opts.UserID > 0 {
 		cond = cond.And(builder.Eq{"user_id": opts.UserID})
 	}
+	if opts.Expired {
+		cond = cond.And(builder.Lt{"expires_at": time.Now()})
+	}
+	if opts.HasRefreshToken {
+		cond = cond.And(builder.Neq{"refresh_token": ""})
+	}
+	if opts.LoginSourceID != 0 {
+		cond = cond.And(builder.Eq{"login_source_id": opts.LoginSourceID})
+	}
 	return cond
 }
 
 func (opts FindExternalUserOptions) ToOrders() string {
 	return opts.OrderBy
 }
+
+func IterateExternalLogin(ctx context.Context, opts FindExternalUserOptions, f func(ctx context.Context, u *ExternalLoginUser) error) error {
+	return db.Iterate(ctx, opts.ToConds(), f)
+}