box: Fixed refresh of tokens with OAuth2.0 and JWT

If you use the authentication method OAuth2.0 with JWT on the Box backend
rclone fails to refresh the token before Box expires it. If this happens
mid-transfer the transfer is aborted. This fix expires the tokens from
Box earlier (2 minutes) than expected.

Fixes #7214

backend/box/box.go

@@ -202,7 +202,9 @@ func refreshJWTToken(ctx context.Context, jsonFile string, boxSubType string, na
 	signingHeaders := getSigningHeaders(boxConfig)
 	queryParams := getQueryParams(boxConfig)
 	client := fshttp.NewClient(ctx)
-	err = jwtutil.Config("box", name, tokenURL, *claims, signingHeaders, queryParams, privateKey, m, client)
+	// When using OAuth2.0 with JWT Box appears to expire their tokens earlier than expected.
+	// To counter this, we manually set the token to expire 2 minutes earlier than expected
+	err = jwtutil.Config("box", name, tokenURL, *claims, signingHeaders, queryParams, privateKey, m, client, 2*time.Minute)
 	return err
 }
 

lib/jwtutil/jwtutil.go

@@ -32,7 +32,7 @@ func RandomHex(n int) (string, error) {
 }
 
 // Config configures rclone using JWT
-func Config(id, name, url string, claims jwt.Claims, headerParams map[string]interface{}, queryParams map[string]string, privateKey *rsa.PrivateKey, m configmap.Mapper, client *http.Client) (err error) {
+func Config(id, name, url string, claims jwt.Claims, headerParams map[string]interface{}, queryParams map[string]string, privateKey *rsa.PrivateKey, m configmap.Mapper, client *http.Client, earlyExpire time.Duration) (err error) {
 	jwtToken := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
 	for key, value := range headerParams {
 		jwtToken.Header[key] = value
@@ -93,7 +93,7 @@ func Config(id, name, url string, claims jwt.Claims, headerParams map[string]int
 	}
 	e := result.ExpiresIn
 	if e != 0 {
-		token.Expiry = time.Now().Add(time.Duration(e) * time.Second)
+		token.Expiry = time.Now().Add(time.Duration(e)*time.Second - earlyExpire)
 	}
 	return oauthutil.PutToken(name, m, token, true)
 }

lib/oauthutil/oauthutil.go

@@ -18,7 +18,6 @@ import (
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/config"
 	"github.com/rclone/rclone/fs/config/configmap"
-	"github.com/rclone/rclone/fs/fserrors"
 	"github.com/rclone/rclone/fs/fshttp"
 	"github.com/rclone/rclone/lib/random"
 	"github.com/skratchdot/open-golang/open"
@@ -266,11 +265,13 @@ func (ts *TokenSource) Token() (*oauth2.Token, error) {
 		if !ts.token.Valid() {
 			if ts.reReadToken() {
 				changed = true
-			} else if ts.token.RefreshToken == "" {
-				return nil, fserrors.FatalError(
-					fmt.Errorf("token expired and there's no refresh token - manually refresh with \"rclone config reconnect %s:\"", ts.name),
-				)
-			}
+			} //else if ts.token.RefreshToken == "" {
+			// FIXME need to detect JWT here
+			// Box authentication OAuth2.0 with JWT does not provide refresh tokens
+			// return nil, fserrors.FatalError(
+			//	fmt.Errorf("token expired and there's no refresh token - manually refresh with \"rclone config reconnect %s:\"", ts.name),
+			//)
+			//}
 		}
 
 		// Make a new token source if required