fix: persist custom date filter across syslog page navigation (#251)

* fix: persist custom date filter across syslog page navigation

When a user sets a custom date range and then navigates to the next
page, the shift_span detection runs before validate_store_request_vars
restores session values. shift_span was false (no date params in the
page link), causing set_shift_span() to fall into the 'span' branch,
which recalculated dates from predefined_timespan and killed the
session date vars -- wiping the custom filter.

Two-part fix:
- In the 'custom' case, save date1/date2 to session (same pattern
  the existing 'shift' case already uses) so page navigation can
  find them.
- Distinguish page navigation with saved custom dates (shift_span
  false + session dates present) from an explicit predefined-timespan
  selection. Only recalculate from predefined_timespan when no custom
  dates are in session.

Fixes #250
Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

* fix: guard session date keys with isset before access in set_shift_span

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

* fix: guard both _date1 and _date2 session keys in set_shift_span

If _date1 exists but _date2 is absent (partial session state), the old
check passed the guard and entered the pagination-restore path. The
inner isset() at line 800 already fell back safely, but the outer guard
now explicitly requires both keys to avoid confusing partial-session
scenarios.

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

* chore: add CHANGELOG entry for develop

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

---------

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

Author: somethingwithproof

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 --- develop ---
 
+* issue#250: Fix date filter persistence by validating before shift_span detection
 * issue: Making changes to support Cacti 1.3
 * issue: Don't use MyISAM for non-analytical tables
 * issue: The install advisor for Syslog was broken in current Cacti releases

syslog.php

@@ -779,7 +779,7 @@ function syslog_request_validation($current_tab, $force = false) {
 function set_shift_span($shift_span, $session_prefix) {
 	global $graph_timeshifts;
 
-	if ($shift_span == 'span' || $shift_span === false) {
+	if ($shift_span == 'span' || ($shift_span === false && (!isset($_SESSION[$session_prefix . '_date1']) || !isset($_SESSION[$session_prefix . '_date2'])))) {
 		$span = array();
 
 		// Calculate the timespan
@@ -795,6 +795,21 @@ function set_shift_span($shift_span, $session_prefix) {
 		kill_session_var($session_prefix . '_date2');
 
 		set_request_var('custom', false);
+	} elseif ($shift_span === false) {
+		// Page navigation: custom dates were set earlier; restore from session.
+		if (isset($_SESSION[$session_prefix . '_date1']) && isset($_SESSION[$session_prefix . '_date2'])) {
+			set_request_var('date1', $_SESSION[$session_prefix . '_date1']);
+			set_request_var('date2', $_SESSION[$session_prefix . '_date2']);
+			set_request_var('custom', true);
+		} else {
+			// Session keys missing; fall back to a fresh span calculation.
+			$first_weekdayid = read_user_setting('first_weekdayid');
+			$span = array();
+			get_timespan($span, time(), get_request_var('predefined_timespan'), $first_weekdayid);
+			set_request_var('date1', date('Y-m-d H:i:s', $span['begin_now']));
+			set_request_var('date2', date('Y-m-d H:i:s', $span['end_now']));
+			set_request_var('custom', false);
+		}
 	} elseif ($shift_span == 'shift') {
 		$span = array();
 
@@ -826,6 +841,9 @@ function set_shift_span($shift_span, $session_prefix) {
 
 		set_request_var('custom', true);
 	} elseif ($shift_span == 'custom') {
+		// Persist custom dates so page navigation preserves the filter.
+		$_SESSION[$session_prefix . '_date1'] = get_request_var('date1');
+		$_SESSION[$session_prefix . '_date2'] = get_request_var('date2');
 		set_request_var('custom', true);
 	}
 }