totp one time recovery code added

totp_saveCode.php

@@ -0,0 +1,85 @@
+<?php
+// totp_saveCode.php
+
+require_once 'config.php';
+
+header('Content-Type: application/json');
+
+// 1) Only allow POST
+if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
+    http_response_code(405);
+    error_log("totp_saveCode: invalid method {$_SERVER['REQUEST_METHOD']}");
+    exit(json_encode(['status'=>'error','message'=>'Method not allowed']));
+}
+
+// 2) CSRF check
+if (empty($_SERVER['HTTP_X_CSRF_TOKEN']) 
+ || $_SERVER['HTTP_X_CSRF_TOKEN'] !== ($_SESSION['csrf_token'] ?? '')) {
+    http_response_code(403);
+    error_log("totp_saveCode: invalid CSRF token from IP {$_SERVER['REMOTE_ADDR']}");
+    exit(json_encode(['status'=>'error','message'=>'Invalid CSRF token']));
+}
+
+// 3) Must be logged in
+if (empty($_SESSION['username'])) {
+    http_response_code(401);
+    error_log("totp_saveCode: unauthorized attempt from IP {$_SERVER['REMOTE_ADDR']}");
+    exit(json_encode(['status'=>'error','message'=>'Unauthorized']));
+}
+
+// 4) Validate username format
+$userId = $_SESSION['username'];
+if (!preg_match('/^[A-Za-z0-9_\-]+$/', $userId)) {
+    http_response_code(400);
+    error_log("totp_saveCode: invalid username format: {$userId}");
+    exit(json_encode(['status'=>'error','message'=>'Invalid user identifier']));
+}
+
+// 5) Ensure user file exists (create if missing)
+$userFile = rtrim(USERS_DIR, '/\\') . DIRECTORY_SEPARATOR . $userId . '.json';
+if (!file_exists($userFile)) {
+    $defaultData = [];
+    if (file_put_contents($userFile, json_encode($defaultData)) === false) {
+        http_response_code(500);
+        error_log("totp_saveCode: failed to create user file: {$userFile}");
+        exit(json_encode(['status'=>'error','message'=>'Server error']));
+    }
+}
+
+// 6) Generate secure recovery code
+function generateRecoveryCode($length = 12) {
+    $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+    $max   = strlen($chars) - 1;
+    $code  = '';
+    for ($i = 0; $i < $length; $i++) {
+        $code .= $chars[random_int(0, $max)];
+    }
+    return $code;
+}
+$recoveryCode = generateRecoveryCode();
+$recoveryHash = password_hash($recoveryCode, PASSWORD_DEFAULT);
+
+// 7) Read, lock, update user file
+$fp = fopen($userFile, 'c+');
+if (!$fp || !flock($fp, LOCK_EX)) {
+    http_response_code(500);
+    error_log("totp_saveCode: failed to lock user file: {$userFile}");
+    exit(json_encode(['status'=>'error','message'=>'Server error']));
+}
+
+$data = json_decode(stream_get_contents($fp), true) ?: [];
+$data['totp_recovery_code'] = $recoveryHash;
+
+rewind($fp);
+ftruncate($fp, 0);
+fwrite($fp, json_encode($data)); // no pretty-print in prod
+fflush($fp);
+flock($fp, LOCK_UN);
+fclose($fp);
+
+// 8) Return one-time recovery code
+echo json_encode([
+    'status'       => 'ok',
+    'recoveryCode' => $recoveryCode
+]);
+exit;