b2: Support Application Keys - fixes #2428

This supports B2 application keys limited to a bucket by making sure
we only list the buckets of the bucket ID that the key is limited to.

backend/b2/api/types.go

@@ -31,11 +31,6 @@ func (e *Error) Fatal() bool {
 
 var _ fserrors.Fataler = (*Error)(nil)
 
-// Account describes a B2 account
-type Account struct {
-	ID string `json:"accountId"` // The identifier for the account.
-}
-
 // Bucket describes a B2 bucket
 type Bucket struct {
 	ID        string `json:"bucketId"`
@@ -137,10 +132,26 @@ type File struct {
 
 // AuthorizeAccountResponse is as returned from the b2_authorize_account call
 type AuthorizeAccountResponse struct {
+	AbsoluteMinimumPartSize int      `json:"absoluteMinimumPartSize"` // The smallest possible size of a part of a large file.
 	AccountID               string   `json:"accountId"`               // The identifier for the account.
-	AuthorizationToken string `json:"authorizationToken"` // An authorization token to use with all calls, other than b2_authorize_account, that need an Authorization header.
+	Allowed                 struct { // An object (see below) containing the capabilities of this auth token, and any restrictions on using it.
+		BucketID     string      `json:"bucketId"`     // When present, access is restricted to one bucket.
+		Capabilities []string    `json:"capabilities"` // A list of strings, each one naming a capability the key has.
+		NamePrefix   interface{} `json:"namePrefix"`   // When present, access is restricted to files whose names start with the prefix
+	} `json:"allowed"`
 	APIURL              string `json:"apiUrl"`              // The base URL to use for all API calls except for uploading and downloading files.
+	AuthorizationToken  string `json:"authorizationToken"`  // An authorization token to use with all calls, other than b2_authorize_account, that need an Authorization header.
 	DownloadURL         string `json:"downloadUrl"`         // The base URL to use for downloading files.
+	MinimumPartSize     int    `json:"minimumPartSize"`     // DEPRECATED: This field will always have the same value as recommendedPartSize. Use recommendedPartSize instead.
+	RecommendedPartSize int    `json:"recommendedPartSize"` // The recommended size for each part of a large file. We recommend using this part size for optimal upload performance.
+}
+
+// ListBucketsRequest is parameters for b2_list_buckets call
+type ListBucketsRequest struct {
+	AccountID   string   `json:"accountId"`             // The identifier for the account.
+	BucketID    string   `json:"bucketId,omitempty"`    // When specified, the result will be a list containing just this bucket.
+	BucketName  string   `json:"bucketName,omitempty"`  // When specified, the result will be a list containing just this bucket.
+	BucketTypes []string `json:"bucketTypes,omitempty"` // If present, B2 will use it as a filter for bucket types returned in the list buckets response.
 }
 
 // ListBucketsResponse is as returned from the b2_list_buckets call

backend/b2/b2.go

@@ -66,7 +66,7 @@ func init() {
 		NewFs:       NewFs,
 		Options: []fs.Option{{
 			Name:     "account",
-			Help:     "Account ID",
+			Help:     "Account ID or Application Key ID",
 			Required: true,
 		}, {
 			Name:     "key",
@@ -691,7 +691,11 @@ type listBucketFn func(*api.Bucket) error
 
 // listBucketsToFn lists the buckets to the function supplied
 func (f *Fs) listBucketsToFn(fn listBucketFn) error {
-	var account = api.Account{ID: f.info.AccountID}
+	var account = api.ListBucketsRequest{
+		AccountID: f.info.AccountID,
+		BucketID:  f.info.Allowed.BucketID,
+	}
+
 	var response api.ListBucketsResponse
 	opts := rest.Opts{
 		Method: "POST",

docs/content/b2.md

@@ -55,7 +55,7 @@ Choose a number from below, or type in your own value
 13 / Yandex Disk
    \ "yandex"
 Storage> 3
-Account ID
+Account ID or Application Key ID
 account> 123456789abc
 Application Key
 key> 0123456789abcdef0123456789abcdef0123456789
@@ -93,6 +93,21 @@ excess files in the bucket.
 
     rclone sync /home/local/directory remote:bucket
 
+### Application Keys ###
+
+B2 supports multiple [Application Keys for different access permission
+to B2 Buckets](https://www.backblaze.com/b2/docs/application_keys.html).
+
+You can use these with rclone too.
+
+Follow Backblaze's docs to create an Application Key with the required
+permission and add the `Application Key ID` as the `account` and the
+`Application Key` itself as the `key`.
+
+Note that you must put the Application Key ID as the `account` - you
+can't use the master Account ID.  If you try then B2 will return 401
+errors.
+
 ### --fast-list ###
 
 This remote supports `--fast-list` which allows you to use fewer