Improve date handling in getDate method

[TDannhauer]

Handle unparseable IMAP envelope dates in getDate()

Summary

• Use Horde_Imap_Client_DateTime::getTimestamp() for valid envelope dates instead of casting the object to string.
• When the envelope date is unparseable (error()), fall back to the message Date header, then to the current time.
• Treat numeric string "0" as invalid (IMAP client error sentinel), not as a Unix timestamp.

Problem

During ActiveSync Sync, Horde_ActiveSync_Imap_EasMessageBuilder::_setHeaderProperties() sets datereceived from Horde_ActiveSync_Imap_Message::getDate(). If new Horde_Date() throws, the Sync response aborts with HTTP 500 and clients retry indefinitely.

Observed log (German locale):

ERR: Returning HTTP 500 while handling Sync command. Error is: Zeitformat (0) nicht erkannt
...
Horde_ActiveSync_Imap_Message->getDate()
Horde_Date->__construct()

The German message is Horde_Date’s “Failed to parse time string (%s)” — here with %s = 0, not “format id 0”.

Root cause

$this->envelope->date is a Horde_Imap_Client_DateTime. When the IMAP layer cannot parse the envelope date, it stores an internal error value and __toString() returns "0":

// Horde_Imap_Client_DateTime
public function __toString()
{
    return $this->error() ? '0' : strval($this->getTimestamp());
}

Previous getDate() logic (after #15’s fix for numeric timestamp strings):

if (is_string($date) && ctype_digit($date)) {
    return new Horde_Date((int) $date);
}
return new Horde_Date((string) $date);

For an error-state envelope date:

1. $date is an object → the ctype_digit branch is skipped.
2. (string) $date → "0".
3. Horde_Date("0") does not accept single-digit timestamp strings → DateTime("0") fails → exception → Sync 500.

This is separate from horde/ActiveSync#15, which fixed valid Unix timestamps passed as 9–11 digit strings (e.g. "1773944669").

Solution

public function getDate()
{
    $date = $this->envelope->date;

    if ($date instanceof Horde_Imap_Client_DateTime) {
        if (!$date->error()) {
            return new Horde_Date($date->getTimestamp());
        }

        $date = $this->getHeaders()->getValue('date') ?: null;
    }

    if (is_string($date) && ctype_digit($date)) {
        $ts = (int) $date;
        if ($ts) {
            return new Horde_Date($ts);
        }
        $date = null;
    }

    if ($date) {
        try {
            return new Horde_Date($date);
        } catch (Horde_Date_Exception $e) {
        }
    }

    return new Horde_Date();
}

Case	Behavior
Valid Horde_Imap_Client_DateTime	new Horde_Date($timestamp)
Unparseable envelope (error())	Parse Date: header; if that fails, use now
Numeric timestamp string (non-zero)	new Horde_Date((int) $string) (#15)
Sentinel "0"	Treated as invalid → fallbacks above

Sync can complete even when individual messages have malformed envelope dates; datereceived may be approximate only when both envelope and header dates fail.

Related work

• horde/ActiveSync#15 — Unix timestamp strings in envelope dates.
• horde/imap_client — Horde_Imap_Client_DateTime error handling and __toString() sentinel (Ticket #14381).
• Intentionally does not change Horde_Date constructor semantics (per upstream discussion on Improve date handling in getDate method #15).

Test plan

• Sync a mailbox that previously triggered Zeitformat (0) nicht erkannt via Outlook or another EAS client; confirm Sync completes without HTTP 500.
• Confirm messages with normal envelope dates still get correct datereceived.
• Test a message with a known-bad envelope date but valid Date: header; confirm the header date is used.
• Test a message with only a numeric timestamp string envelope (regression for Improve date handling in getDate method #15); confirm sync still works.
• Check Horde logs: no Horde_Date_Exception from getDate() during Sync for the above cases.

[TDannhauer]

@ralflang please verify whether this is a valid approach, you are deeper in the date corner.