fix: drop duplicate count query; cache upstream version failures

- global_stats() executed the 'last N seconds' COUNT twice per page
  load (prepare()->execute() result was discarded, then re-run)
- fetch_upstream_version() cached nothing on failure, so an
  unreachable git server added a cURL wait (up to 5 s) to every
  dashboard load via the 30 s auto-refresh; failures are now cached
  for 15 minutes and get a 2 s connect timeout

includes/functions.php

@@ -274,18 +274,24 @@ function purge_old_connections(): int {
 define('UPSTREAM_VERSION_URL', 'https://git.ny.daprogs.com/api/v1/repos/DAProgs/portspoof_concentrator/raw/version.php?ref=main');
 define('UPSTREAM_VERSION_CACHE', __DIR__ . '/../upstream_version.cache');
 define('UPSTREAM_VERSION_TTL', 3600); // seconds
+define('UPSTREAM_VERSION_FAIL_TTL', 900); // seconds — how long to cache a failed check
 
 /**
  * Fetch the upstream version string from the git repo, with a 1-hour file cache.
  * Returns null silently on any failure so the page always loads.
+ *
+ * Failures are cached briefly too, so an unreachable git server does not
+ * add a cURL wait to every dashboard load (the page auto-refreshes every 30 s).
  */
 function fetch_upstream_version(): ?string {
-    // Return cached value if still fresh
+    // Return cached value (success or failure) if still fresh
     if (file_exists(UPSTREAM_VERSION_CACHE)) {
         $cached = json_decode(file_get_contents(UPSTREAM_VERSION_CACHE), true);
-        if (isset($cached['version'], $cached['checked_at'])
-            && (time() - $cached['checked_at']) < UPSTREAM_VERSION_TTL) {
-            return $cached['version'];
+        if (isset($cached['checked_at'])) {
+            $ttl = isset($cached['version']) ? UPSTREAM_VERSION_TTL : UPSTREAM_VERSION_FAIL_TTL;
+            if ((time() - $cached['checked_at']) < $ttl) {
+                return $cached['version'] ?? null;
+            }
         }
     }
 
@@ -293,27 +299,30 @@ function fetch_upstream_version(): ?string {
     curl_setopt_array($ch, [
         CURLOPT_RETURNTRANSFER => true,
         CURLOPT_TIMEOUT        => 5,
+        CURLOPT_CONNECTTIMEOUT => 2,
         CURLOPT_FOLLOWLOCATION => true,
     ]);
     $body = curl_exec($ch);
     $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
     curl_close($ch);
 
-    if ($body === false || $code !== 200) {
-        return null;
+    if ($body !== false && $code === 200
+        && preg_match("/define\s*\(\s*'APP_VERSION'\s*,\s*'([^']+)'\s*\)/", $body, $m)) {
+        file_put_contents(
+            UPSTREAM_VERSION_CACHE,
+            json_encode(['version' => $m[1], 'checked_at' => time()]),
+            LOCK_EX
+        );
+        return $m[1];
     }
 
-    if (!preg_match("/define\s*\(\s*'APP_VERSION'\s*,\s*'([^']+)'\s*\)/", $body, $m)) {
-        return null;
-    }
-
-    $version = $m[1];
+    // Cache the failure so we don't retry on every page load
     file_put_contents(
         UPSTREAM_VERSION_CACHE,
-        json_encode(['version' => $version, 'checked_at' => time()]),
+        json_encode(['version' => null, 'checked_at' => time()]),
         LOCK_EX
     );
-    return $version;
+    return null;
 }
 
 /**
@@ -366,8 +375,6 @@ function global_stats(): array {
     $total = (int)$pdo->query('SELECT COUNT(*) FROM connections')->fetchColumn();
 
     $since = date('Y-m-d H:i:s', time() - RATE_WINDOW_SECONDS);
-    $recent = (int)$pdo->prepare('SELECT COUNT(*) FROM connections WHERE occurred_at >= ?')
-                        ->execute([$since]) ? : 0;
     $s = $pdo->prepare('SELECT COUNT(*) FROM connections WHERE occurred_at >= ?');
     $s->execute([$since]);
     $recent = (int)$s->fetchColumn();