flow_refresh.go

/*
 * Copyright © 2015-2018 Aeneas Rekkas <aeneas+oss@aeneas.io>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @author		Aeneas Rekkas <aeneas+oss@aeneas.io>
 * @copyright 	2015-2018 Aeneas Rekkas <aeneas+oss@aeneas.io>
 * @license 	Apache-2.0
 *
 */

package oauth2

import (
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/ory/x/errorsx"
	"github.com/pkg/errors"

	"github.com/ory/fosite"
	"github.com/ory/fosite/storage"
)

var _ fosite.TokenEndpointHandler = (*RefreshTokenGrantHandler)(nil)

type RefreshTokenGrantHandler struct {
	AccessTokenStrategy    AccessTokenStrategy
	RefreshTokenStrategy   RefreshTokenStrategy
	TokenRevocationStorage TokenRevocationStorage
	Config                 interface {
		fosite.AccessTokenLifespanProvider
		fosite.RefreshTokenLifespanProvider
		fosite.ScopeStrategyProvider
		fosite.AudienceStrategyProvider
		fosite.RefreshTokenScopesProvider
	}
}

// HandleTokenEndpointRequest implements https://tools.ietf.org/html/rfc6749#section-6
func (c *RefreshTokenGrantHandler) HandleTokenEndpointRequest(ctx context.Context, request fosite.AccessRequester) error {
	if !c.CanHandleTokenEndpointRequest(ctx, request) {
		return errorsx.WithStack(fosite.ErrUnknownRequest)
	}

	if !request.GetClient().GetGrantTypes().Has("refresh_token") {
		return errorsx.WithStack(fosite.ErrUnauthorizedClient.WithHint("The OAuth 2.0 Client is not allowed to use authorization grant 'refresh_token'."))
	}

	refresh := request.GetRequestForm().Get("refresh_token")
	signature := c.RefreshTokenStrategy.RefreshTokenSignature(ctx, refresh)
	originalRequest, err := c.TokenRevocationStorage.GetRefreshTokenSession(ctx, signature, request.GetSession())
	if errors.Is(err, fosite.ErrInactiveToken) {
		// Detected refresh token reuse
		if rErr := c.handleRefreshTokenReuse(ctx, signature, originalRequest); rErr != nil {
			return errorsx.WithStack(fosite.ErrServerError.WithWrap(rErr).WithDebug(rErr.Error()))
		}

		return errorsx.WithStack(fosite.ErrInactiveToken.WithWrap(err).WithDebug(err.Error()))
	} else if errors.Is(err, fosite.ErrNotFound) {
		return errorsx.WithStack(fosite.ErrInvalidGrant.WithWrap(err).WithDebugf("The refresh token has not been found: %s", err.Error()))
	} else if err != nil {
		return errorsx.WithStack(fosite.ErrServerError.WithWrap(err).WithDebug(err.Error()))
	} else if err := c.RefreshTokenStrategy.ValidateRefreshToken(ctx, originalRequest, refresh); err != nil {
		// The authorization server MUST ... validate the refresh token.
		// This needs to happen after store retrieval for the session to be hydrated properly
		if errors.Is(err, fosite.ErrTokenExpired) {
			return errorsx.WithStack(fosite.ErrInvalidGrant.WithWrap(err).WithDebug(err.Error()))
		}
		return errorsx.WithStack(fosite.ErrInvalidRequest.WithWrap(err).WithDebug(err.Error()))
	}

	if !(len(c.Config.GetRefreshTokenScopes(ctx)) == 0 || originalRequest.GetGrantedScopes().HasOneOf(c.Config.GetRefreshTokenScopes(ctx)...)) {
		scopeNames := strings.Join(c.Config.GetRefreshTokenScopes(ctx), " or ")
		hint := fmt.Sprintf("The OAuth 2.0 Client was not granted scope %s and may thus not perform the 'refresh_token' authorization grant.", scopeNames)
		return errorsx.WithStack(fosite.ErrScopeNotGranted.WithHint(hint))

	}

	// The authorization server MUST ... and ensure that the refresh token was issued to the authenticated client
	if originalRequest.GetClient().GetID() != request.GetClient().GetID() {
		return errorsx.WithStack(fosite.ErrInvalidGrant.WithHint("The OAuth 2.0 Client ID from this request does not match the ID during the initial token issuance."))
	}

	request.SetSession(originalRequest.GetSession().Clone())

	/*
			There are two key points in the following spec section this addresses:
				1. If omitted the scope param should be treated as the same as the scope originally granted by the resource owner.
				2. The REQUESTED scope MUST NOT include any scope not originally granted.

			scope
					OPTIONAL.  The scope of the access request as described by Section 3.3.  The requested scope MUST NOT
		  			include any scope not originally granted by the resource owner, and if omitted is treated as equal to
		   			the scope originally granted by the resource owner.

			See https://www.rfc-editor.org/rfc/rfc6749#section-6
	*/
	switch scope := request.GetRequestForm().Get("scope"); scope {
	case "":
		// Addresses point 1 of the text in RFC6749 Section 6.
		request.SetRequestedScopes(originalRequest.GetGrantedScopes())
	default:
		request.SetRequestedScopes(fosite.RemoveEmpty(strings.Split(scope, " ")))
	}

	request.SetRequestedAudience(originalRequest.GetRequestedAudience())

	for _, scope := range request.GetRequestedScopes() {
		// Addresses point 2 of the text in RFC6749 Section 6.
		if !originalRequest.GetGrantedScopes().Has(scope) {
			return errorsx.WithStack(fosite.ErrInvalidScope.WithHintf("The requested scope '%s' was not originally granted by the resource owner.", scope))
		}

		if !c.Config.GetScopeStrategy(ctx)(request.GetClient().GetScopes(), scope) {
			return errorsx.WithStack(fosite.ErrInvalidScope.WithHintf("The OAuth 2.0 Client is not allowed to request scope '%s'.", scope))
		}

		request.GrantScope(scope)
	}

	if err := c.Config.GetAudienceStrategy(ctx)(request.GetClient().GetAudience(), originalRequest.GetGrantedAudience()); err != nil {
		return err
	}

	for _, audience := range originalRequest.GetGrantedAudience() {
		request.GrantAudience(audience)
	}

	atLifespan := fosite.GetEffectiveLifespan(request.GetClient(), fosite.GrantTypeRefreshToken, fosite.AccessToken, c.Config.GetAccessTokenLifespan(ctx))
	request.GetSession().SetExpiresAt(fosite.AccessToken, time.Now().UTC().Add(atLifespan).Round(time.Second))

	rtLifespan := fosite.GetEffectiveLifespan(request.GetClient(), fosite.GrantTypeRefreshToken, fosite.RefreshToken, c.Config.GetRefreshTokenLifespan(ctx))
	if rtLifespan > -1 {
		request.GetSession().SetExpiresAt(fosite.RefreshToken, time.Now().UTC().Add(rtLifespan).Round(time.Second))
	}

	return nil
}

// PopulateTokenEndpointResponse implements https://tools.ietf.org/html/rfc6749#section-6
func (c *RefreshTokenGrantHandler) PopulateTokenEndpointResponse(ctx context.Context, requester fosite.AccessRequester, responder fosite.AccessResponder) (err error) {
	if !c.CanHandleTokenEndpointRequest(ctx, requester) {
		return errorsx.WithStack(fosite.ErrUnknownRequest)
	}

	accessToken, accessSignature, err := c.AccessTokenStrategy.GenerateAccessToken(ctx, requester)
	if err != nil {
		return errorsx.WithStack(fosite.ErrServerError.WithWrap(err).WithDebug(err.Error()))
	}

	refreshToken, refreshSignature, err := c.RefreshTokenStrategy.GenerateRefreshToken(ctx, requester)
	if err != nil {
		return errorsx.WithStack(fosite.ErrServerError.WithWrap(err).WithDebug(err.Error()))
	}

	signature := c.RefreshTokenStrategy.RefreshTokenSignature(ctx, requester.GetRequestForm().Get("refresh_token"))

	ctx, err = storage.MaybeBeginTx(ctx, c.TokenRevocationStorage)
	if err != nil {
		return errorsx.WithStack(fosite.ErrServerError.WithWrap(err).WithDebug(err.Error()))
	}
	defer func() {
		err = c.handleRefreshTokenEndpointStorageError(ctx, err)
	}()

	ts, err := c.TokenRevocationStorage.GetRefreshTokenSession(ctx, signature, nil)
	if err != nil {
		return err
	} else if err := c.TokenRevocationStorage.RevokeAccessToken(ctx, ts.GetID()); err != nil {
		return err
	}

	if err := c.TokenRevocationStorage.RevokeRefreshTokenMaybeGracePeriod(ctx, ts.GetID(), signature); err != nil {
		return err
	}

	storeReq := requester.Sanitize([]string{})
	storeReq.SetID(ts.GetID())

	if err = c.TokenRevocationStorage.CreateAccessTokenSession(ctx, accessSignature, storeReq); err != nil {
		return err
	}

	if err = c.TokenRevocationStorage.CreateRefreshTokenSession(ctx, refreshSignature, storeReq); err != nil {
		return err
	}

	responder.SetAccessToken(accessToken)
	responder.SetTokenType("bearer")
	atLifespan := fosite.GetEffectiveLifespan(requester.GetClient(), fosite.GrantTypeRefreshToken, fosite.AccessToken, c.Config.GetAccessTokenLifespan(ctx))
	responder.SetExpiresIn(getExpiresIn(requester, fosite.AccessToken, atLifespan, time.Now().UTC()))
	responder.SetScopes(requester.GetGrantedScopes())
	responder.SetExtra("refresh_token", refreshToken)

	if err = storage.MaybeCommitTx(ctx, c.TokenRevocationStorage); err != nil {
		return err
	}

	return nil
}

// Reference: https://tools.ietf.org/html/rfc6819#section-5.2.2.3
//
//	The basic idea is to change the refresh token
//	value with every refresh request in order to detect attempts to
//	obtain access tokens using old refresh tokens.  Since the
//	authorization server cannot determine whether the attacker or the
//	legitimate client is trying to access, in case of such an access
//	attempt the valid refresh token and the access authorization
//	associated with it are both revoked.
func (c *RefreshTokenGrantHandler) handleRefreshTokenReuse(ctx context.Context, signature string, req fosite.Requester) (err error) {
	ctx, err = storage.MaybeBeginTx(ctx, c.TokenRevocationStorage)
	if err != nil {
		return errorsx.WithStack(fosite.ErrServerError.WithWrap(err).WithDebug(err.Error()))
	}
	defer func() {
		err = c.handleRefreshTokenEndpointStorageError(ctx, err)
	}()

	if err = c.TokenRevocationStorage.DeleteRefreshTokenSession(ctx, signature); err != nil {
		return err
	} else if err = c.TokenRevocationStorage.RevokeRefreshToken(
		ctx, req.GetID(),
	); err != nil && !errors.Is(err, fosite.ErrNotFound) {
		return err
	} else if err = c.TokenRevocationStorage.RevokeAccessToken(
		ctx, req.GetID(),
	); err != nil && !errors.Is(err, fosite.ErrNotFound) {
		return err
	}

	if err = storage.MaybeCommitTx(ctx, c.TokenRevocationStorage); err != nil {
		return err
	}

	return nil
}

func (c *RefreshTokenGrantHandler) handleRefreshTokenEndpointStorageError(ctx context.Context, storageErr error) (err error) {
	if storageErr == nil {
		return nil
	}

	defer func() {
		if rollBackTxnErr := storage.MaybeRollbackTx(ctx, c.TokenRevocationStorage); rollBackTxnErr != nil {
			err = errorsx.WithStack(fosite.ErrServerError.WithWrap(err).WithDebugf("error: %s; rollback error: %s", err, rollBackTxnErr))
		}
	}()

	if errors.Is(storageErr, fosite.ErrSerializationFailure) {
		return errorsx.WithStack(fosite.ErrInvalidRequest.
			WithDebugf(storageErr.Error()).
			WithHint("Failed to refresh token because of multiple concurrent requests using the same token which is not allowed."))
	}

	if errors.Is(storageErr, fosite.ErrNotFound) || errors.Is(storageErr, fosite.ErrInactiveToken) {
		return errorsx.WithStack(fosite.ErrInvalidRequest.
			WithDebugf(storageErr.Error()).
			WithHint("Failed to refresh token because of multiple concurrent requests using the same token which is not allowed."))
	}

	return errorsx.WithStack(fosite.ErrServerError.WithWrap(storageErr).WithDebug(storageErr.Error()))
}

func (c *RefreshTokenGrantHandler) CanSkipClientAuth(ctx context.Context, requester fosite.AccessRequester) bool {
	return false
}

func (c *RefreshTokenGrantHandler) CanHandleTokenEndpointRequest(ctx context.Context, requester fosite.AccessRequester) bool {
	// grant_type REQUIRED.
	// Value MUST be set to "refresh_token".
	return requester.GetGrantTypes().ExactOne("refresh_token")
}