Mirrors/chatmail-core
1
0
Fork 0
mirror of https://github.com/chatmail/core.git synced 2026-04-17 21:46:35 +03:00
Code Issues Packages Projects Releases Wiki Activity

fix(imap): always advance expected UIDNEXT to avoid skipping IDLE in a loop

Browse Source 
Ensure the client does not busy loop
skipping IDLE if UIDNEXT of the mailbox is higher than
the last seen UID plus 1, e.g. if the message
with UID=UIDNEXT-1 was deleted before we fetched it.

We do not fallback to UIDNEXT=1 anymore
if the STATUS command cannot determine UIDNEXT.
There are no known IMAP servers with broken STATUS so far.
This allows to guarantee that select_with_uidvalidity()
sets UIDNEXT for the mailbox and use it in fetch_new_messages()
to ensure that UIDNEXT always advances even
when there are no messages to fetch.
This commit is contained in:
link2xt
2023-11-06 01:50:32 +00:00
parent 5549733a0b
commit 7b83bddc2d
2 changed files with 66 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

119
src/imap.rs
View File

@@ -568,9 +568,14 @@ impl Imap {
Ok(())
}
/// Select a folder and take care of uidvalidity changes.
/// Also, when selecting a folder for the first time, sets the uid_next to the current
/// Selects a folder and takes care of UIDVALIDITY changes.
///
/// When selecting a folder for the first time, sets the uid_next to the current
/// mailbox.uid_next so that no old emails are fetched.
///
/// Makes sure that UIDNEXT is known for `selected_mailbox`
/// and errors out if UIDNEXT cannot be determined.
///
/// Returns Result<new_emails> (i.e. whether new emails arrived),
/// if in doubt, returns new_emails=true so emails are fetched.
pub(crate) async fn select_with_uidvalidity(
@@ -591,6 +596,37 @@ impl Imap {
let new_uid_validity = mailbox
.uid_validity
.with_context(|| format!("No UIDVALIDITY for folder {folder}"))?;
let new_uid_next = if let Some(uid_next) = mailbox.uid_next {
uid_next
} else {
warn!(
context,
"SELECT response for IMAP folder {folder:?} has no UIDNEXT, fall back to STATUS command."
);
// RFC 3501 says STATUS command SHOULD NOT be used
// on the currently selected mailbox because the same
// information can be obtained by other means,
// such as reading SELECT response.
//
// However, it also says that UIDNEXT is REQUIRED
// in the SELECT response and if we are here,
// it is actually not returned.
//
// In particular, Winmail Pro Mail Server 5.1.0616
// never returns UIDNEXT in SELECT response,
// but responds to "STATUS INBOX (UIDNEXT)" command.
let status = session
.inner
.status(folder, "(UIDNEXT)")
.await
.context("STATUS (UIDNEXT) error for {folder:?}")?;
status
.uid_next
.context("STATUS {folder} (UIDNEXT) did not return UIDNEXT")?
};
mailbox.uid_next = Some(new_uid_next);
let old_uid_validity = get_uidvalidity(context, folder)
.await
@@ -606,18 +642,16 @@ impl Imap {
// the caller tries to fetch new messages (we could of course run a SELECT command now, but trying to fetch
// new messages is only one command, just as a SELECT command)
true
} else if let Some(uid_next) = mailbox.uid_next {
if uid_next < old_uid_next {
} else {
if new_uid_next < old_uid_next {
warn!(
context,
"The server illegally decreased the uid_next of folder {folder:?} from {old_uid_next} to {uid_next} without changing validity ({new_uid_validity}), resyncing UIDs...",
"The server illegally decreased the uid_next of folder {folder:?} from {old_uid_next} to {new_uid_next} without changing validity ({new_uid_validity}), resyncing UIDs...",
);
set_uid_next(context, folder, uid_next).await?;
set_uid_next(context, folder, new_uid_next).await?;
context.schedule_resync().await?;
}
uid_next != old_uid_next // If uid_next changed, there are new emails
} else {
true // We have no uid_next and if in doubt, return true
new_uid_next != old_uid_next // If UIDNEXT changed, there are new emails
};
return Ok(new_emails);
}
@@ -627,43 +661,6 @@ impl Imap {
// ============== uid_validity has changed or is being set the first time. ==============
let new_uid_next = match mailbox.uid_next {
Some(uid_next) => uid_next,
None => {
warn!(
context,
"SELECT response for IMAP folder {folder:?} has no UIDNEXT, fall back to STATUS command."
);
// RFC 3501 says STATUS command SHOULD NOT be used
// on the currently selected mailbox because the same
// information can be obtained by other means,
// such as reading SELECT response.
//
// However, it also says that UIDNEXT is REQUIRED
// in the SELECT response and if we are here,
// it is actually not returned.
//
// In particular, Winmail Pro Mail Server 5.1.0616
// never returns UIDNEXT in SELECT response,
// but responds to "SELECT INBOX (UIDNEXT)" command.
let status = session
.inner
.status(folder, "(UIDNEXT)")
.await
.context("STATUS (UIDNEXT) error for {folder:?}")?;
if let Some(uid_next) = status.uid_next {
uid_next
} else {
warn!(context, "STATUS {folder} (UIDNEXT) did not return UIDNEXT");
// Set UIDNEXT to 1 as a last resort fallback.
1
}
}
};
set_uid_next(context, folder, new_uid_next).await?;
set_uidvalidity(context, folder, new_uid_validity).await?;
@@ -867,14 +864,28 @@ impl Imap {
uids_fetch_in_batch.push(uid);
}
// determine which uid_next to use to update to
// receive_imf() returns an `Err` value only on recoverable errors, otherwise it just logs an error.
// `largest_uid_processed` is the largest uid where receive_imf() did NOT return an error.
// So: Update the uid_next to the largest uid that did NOT recoverably fail. Not perfect because if there was
// another message afterwards that succeeded, we will not retry. The upside is that we will not retry an infinite amount of times.
let largest_uid_without_errors = max(largest_uid_fetched, largest_uid_skipped.unwrap_or(0));
let new_uid_next = largest_uid_without_errors + 1;
// Advance uid_next to the maximum of the largest known UID plus 1
// and mailbox UIDNEXT.
// Largest known UID is normally less than UIDNEXT,
// but a message may have arrived between determining UIDNEXT
// and executing the FETCH command.
let mailbox_uid_next = self
.session
.as_ref()
.context("No IMAP session")?
.selected_mailbox
.as_ref()
.with_context(|| format!("Expected {folder:?} to be selected"))?
.uid_next
.with_context(|| {
format!(
"Expected UIDNEXT to be determined for {folder:?} by select_with_uidvalidity"
)
})?;
let new_uid_next = max(
max(largest_uid_fetched, largest_uid_skipped.unwrap_or(0)) + 1,
mailbox_uid_next,
);
if new_uid_next > old_uid_next {
set_uid_next(context, folder, new_uid_next).await?;

2
src/imap/idle.rs
View File

@@ -53,7 +53,7 @@ impl Session {
if uid_next > expected_uid_next {
info!(
context,
"Skipping IDLE because UIDNEXT indicates there are new messages."
"Skipping IDLE on {folder:?} because UIDNEXT {uid_next}>{expected_uid_next} indicates there are new messages."
);
return Ok((self, info));
}