[bugfix] check remote status permissibility (#2703)

* add more stringent checks for remote status permissibility

* add check for inreplyto of a remote status being a boost

* do not permit inReplyTo boost wrapper statuses

* change comment wording

* fix calls to NewFederator()

* add code comments for NotPermitted() and SetNotPermitted()

* improve comment

* check that existing != nil before attempting delete

* ensure replying account isn't suspended

* use a debug log instead of info. check for boost using ID

* shorten log string length. make info level

* add note that replying to boost wrapper status shouldn't be able to happen anyways

* update to use onFail() function

1 files changed, 19 insertions, 4 deletions

diff --git a/internal/gtserror/error.go b/internal/gtserror/error.go
index dc4c5a504..a39b5475c 100644
--- a/internal/gtserror/error.go
+++ b/internal/gtserror/error.go
@@ -39,13 +39,13 @@ const (
 	malformedKey
 	notRelevantKey
 	spamKey
+	notPermittedKey
 )
 
 // IsUnretrievable indicates that a call to retrieve a resource
-// (account, status, attachment, etc) could not be fulfilled,
-// either because it was not found locally, or because some
-// prerequisite remote resource call failed, making it impossible
-// to return the item.
+// (account, status, attachment, etc) could not be fulfilled, either
+// because it was not found locally, or because some prerequisite
+// remote resource call failed, making it impossible to return it.
 func IsUnretrievable(err error) bool {
 	_, ok := errors.Value(err, unrtrvableKey).(struct{})
 	return ok
@@ -57,6 +57,21 @@ func SetUnretrievable(err error) error {
 	return errors.WithValue(err, unrtrvableKey, struct{}{})
 }
 
+// NotPermitted indicates that some call failed due to failed permission
+// or acceptibility checks. For example an attempt to dereference remote
+// status in which the status author does not have permission to reply
+// to the status it is intended to be replying to.
+func NotPermitted(err error) bool {
+	_, ok := errors.Value(err, notPermittedKey).(struct{})
+	return ok
+}
+
+// SetNotPermitted will wrap the given error to store a "not permitted"
+// flag, returning wrapped error. See NotPermitted() for example use-cases.
+func SetNotPermitted(err error) error {
+	return errors.WithValue(err, notPermittedKey, struct{}{})
+}
+
 // IsWrongType checks error for a stored "wrong type" flag.
 // Wrong type indicates that an ActivityPub URI returned a
 // type we weren't expecting. For example: