Implement OpenID module (#599) (#1812)

* Implement OpenID module (#599)

- Unrelated: change Riot references to Element in client API routing

Signed-off-by: Bruce MacDonald <contact@bruce-macdonald.com>

* OpenID module tweaks (#599)

- specify expiry is ms rather than vague ts
- add OpenID token lifetime to configuration
- use Go naming conventions for the path params
- store plaintext token rather than hash
- remove openid table sqllite mutex

* Add default OpenID token lifetime (#599)

* Update dendrite-config.yaml

Co-authored-by: Kegsay <kegsay@gmail.com>
Co-authored-by: Kegsay <kegan@matrix.org>

userapi/internal/api.go

@@ -414,3 +414,31 @@ func (a *UserInternalAPI) PerformAccountDeactivation(ctx context.Context, req *a
 	res.AccountDeactivated = err == nil
 	return err
 }
+
+// PerformOpenIDTokenCreation creates a new token that a relying party uses to authenticate a user
+func (a *UserInternalAPI) PerformOpenIDTokenCreation(ctx context.Context, req *api.PerformOpenIDTokenCreationRequest, res *api.PerformOpenIDTokenCreationResponse) error {
+	token := util.RandomString(24)
+
+	exp, err := a.AccountDB.CreateOpenIDToken(ctx, token, req.UserID)
+
+	res.Token = api.OpenIDToken{
+		Token:       token,
+		UserID:      req.UserID,
+		ExpiresAtMS: exp,
+	}
+
+	return err
+}
+
+// QueryOpenIDToken validates that the OpenID token was issued for the user, the replying party uses this for validation
+func (a *UserInternalAPI) QueryOpenIDToken(ctx context.Context, req *api.QueryOpenIDTokenRequest, res *api.QueryOpenIDTokenResponse) error {
+	openIDTokenAttrs, err := a.AccountDB.GetOpenIDTokenAttributes(ctx, req.Token)
+	if err != nil {
+		return err
+	}
+
+	res.Sub = openIDTokenAttrs.UserID
+	res.ExpiresAtMS = openIDTokenAttrs.ExpiresAtMS
+
+	return nil
+}