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GODT-797 APPEND waits for EXPUNGE to prevent data loss when Outlook moves from Spam or Trash

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This commit is contained in:
Michal Horejsek
2021-02-12 10:08:00 +01:00
parent bad8cad97d
commit e6ae344f1f
3 changed files with 30 additions and 26 deletions
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21
internal/imap/mailbox.go
View File

@ -177,16 +177,11 @@ func (im *imapMailbox) Check() error {
// Expunge permanently removes all messages that have the \Deleted flag set
// from the currently selected mailbox.
func (im *imapMailbox) Expunge() error {
// Wait for any APPENDS to finish in order to avoid data loss when
// Outlook sends commands too quickly STORE \Deleted, APPEND, EXPUNGE,
// APPEND FINISHED:
//
// Based on Outlook APPEND request we will not create new message but
// move the original to desired mailbox. If the message is currently
// in Trash or Spam and EXPUNGE happens before APPEND processing is
// finished the message is deleted from Proton instead of moved to
// the desired mailbox.
im.user.waitForAppend()
// See comment of appendExpungeLock.
if im.storeMailbox.LabelID() == pmapi.TrashLabel || im.storeMailbox.LabelID() == pmapi.SpamLabel {
im.user.appendExpungeLock.Lock()
defer im.user.appendExpungeLock.Unlock()
}
im.user.backend.updates.block(im.user.currentAddressLowercase, im.name, operationDeleteMessage)
defer im.user.backend.updates.unblock(im.user.currentAddressLowercase, im.name, operationDeleteMessage)
@ -197,6 +192,12 @@ func (im *imapMailbox) Expunge() error {
// UIDExpunge permanently removes messages that have the \Deleted flag set
// and UID passed from SeqSet from the currently selected mailbox.
func (im *imapMailbox) UIDExpunge(seqSet *imap.SeqSet) error {
// See comment of appendExpungeLock.
if im.storeMailbox.LabelID() == pmapi.TrashLabel || im.storeMailbox.LabelID() == pmapi.SpamLabel {
im.user.appendExpungeLock.Lock()
defer im.user.appendExpungeLock.Unlock()
}
im.user.backend.updates.block(im.user.currentAddressLowercase, im.name, operationDeleteMessage)
defer im.user.backend.updates.unblock(im.user.currentAddressLowercase, im.name, operationDeleteMessage)

6
internal/imap/mailbox_message.go
View File

@ -70,9 +70,6 @@ func (im *imapMailbox) CreateMessage(flags []string, date time.Time, body imap.L
// Called from go-imap in goroutines - we need to handle panics for each function.
defer im.panicHandler.HandlePanic()
im.user.appendStarted()
defer im.user.appendFinished()
m, _, _, readers, err := message.Parse(body)
if err != nil {
return err
@ -154,6 +151,9 @@ func (im *imapMailbox) CreateMessage(flags []string, date time.Time, body imap.L
}
}
im.user.appendExpungeLock.Lock()
defer im.user.appendExpungeLock.Unlock()
// Avoid appending a message which is already on the server. Apply the
// new label instead. This always happens with Outlook (it uses APPEND
// instead of COPY).

29
internal/imap/user.go
View File

@ -41,7 +41,22 @@ type imapUser struct {
currentAddressLowercase string
appendInProcess sync.WaitGroup
// Some clients, for example Outlook, do MOVE by STORE \Deleted, APPEND,
// EXPUNGE where APPEN and EXPUNGE can go in parallel. Usual IMAP servers
// do not deduplicate messages and this it's not an issue, but for APPEND
// for PM means just assigning label. That would cause to assign label and
// then delete the message, or in other words cause data loss.
// go-imap does not call CreateMessage till it gets the whole message from
// IMAP client, therefore with big message, simple wait for APPEND before
// performing EXPUNGE is not enough. There has to be two-way lock. Only
// that way even if EXPUNGE is called few ms before APPEND and message
// is deleted, APPEND will not just assing label but creates the message
// again.
// The issue is only when moving message from folder which is causing
// real removal, so Trash and Spam. Those only need to use the lock to
// not cause huge slow down as EXPUNGE is implicitly called also after
// UNSELECT, CLOSE, or LOGOUT.
appendExpungeLock sync.Mutex
}
// newIMAPUser returns struct implementing go-imap/user interface.
@ -251,15 +266,3 @@ func (iu *imapUser) CreateMessageLimit() *uint32 {
upload := uint32(maxUpload)
return &upload
}
func (iu *imapUser) appendStarted() {
iu.appendInProcess.Add(1)
}
func (iu *imapUser) appendFinished() {
iu.appendInProcess.Done()
}
func (iu *imapUser) waitForAppend() {
iu.appendInProcess.Wait()
}