From b52f0b0eb3810fa6718d15b4e7b1a3a73e6759a9 Mon Sep 17 00:00:00 2001
From: Skylar Ittner <skylar@netsyms.com>
Date: Fri, 26 Jun 2020 21:09:21 -0600
Subject: [PATCH] Calculate check digit for machine/component ID, warn public
 users of typos

---
 lib/CheckDigit.lib.php | 48 ++++++++++++++++++++++++++++++++++++++++++
 lib/Component.lib.php  |  9 ++++++--
 lib/Machine.lib.php    |  9 ++++++--
 public/index.php       | 31 ++++++++++++++++++++++++++-
 4 files changed, 92 insertions(+), 5 deletions(-)
 create mode 100644 lib/CheckDigit.lib.php

diff --git a/lib/CheckDigit.lib.php b/lib/CheckDigit.lib.php
new file mode 100644
index 0000000..b30d515
--- /dev/null
+++ b/lib/CheckDigit.lib.php
@@ -0,0 +1,48 @@
+<?php
+
+/*
+ * Copyright 2020 Netsyms Technologies.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+class CheckDigit {
+
+    /**
+     * https://en.wikipedia.org/wiki/S10_(UPU_standard)#Check-digit_calculation
+     * @param $number 8-digit number (int or string). Digits to the right of the eighth are ignored
+     * when calculating the checksum.
+     * @return int
+     */
+    public static function S10($number): int {
+        $weights = [8, 6, 4, 2, 3, 5, 9, 7];
+        $sum = 0;
+        $digits = str_split(str_pad("$number", 8, "0", STR_PAD_LEFT));
+        for ($i = 0; $i < 8; $i++) {
+            $sum += $digits[$i] * $weights[$i];
+        }
+        $sum = 11 - ($sum % 11);
+        if ($sum == 10) {
+            $sum = 0;
+        } else if ($sum == 11) {
+            $sum = 5;
+        }
+        return $sum;
+    }
+
+    /**
+     * Check if the given number has a valid S10 check digit at index 8 (ninth counting from 1).
+     * @param type $number
+     * @return bool
+     */
+    public static function validateS10($number): bool {
+        $numberpad = str_pad("$number", 9, "0", STR_PAD_LEFT);
+        $digits = str_split($numberpad);
+
+        $realcheckdigit = CheckDigit::S10($number);
+
+        return ($digits[8] == $realcheckdigit);
+    }
+
+}
diff --git a/lib/Component.lib.php b/lib/Component.lib.php
index b595d50..af45364 100644
--- a/lib/Component.lib.php
+++ b/lib/Component.lib.php
@@ -231,17 +231,22 @@ class Component implements JsonSerializable {
 
     /**
      * Generate a random ID number that is not in use.
-     * Default: 681######
+     * Default: 681#####[check digit]
      * @global $database
      * @param int $min Optional minimum number.
      * @param int $max Optional maximum number.
      * @return int
      */
-    public static function generateId(int $min = 681000000, int $max = 681999999): int {
+    public static function generateId(int $min = 68100000, int $max = 68199999): int {
         global $database;
 
         do {
             $id = random_int($min, $max);
+
+            // If default gen add check digit
+            if ($id >= 68100000 && $id <= 68199999) {
+                $id = ("$id" . CheckDigit::S10($id)) * 1;
+            }
         } while ($database->has('components', ['compid' => $id]) || $database->has('machines', ['machineid' => $id]));
 
         return $id;
diff --git a/lib/Machine.lib.php b/lib/Machine.lib.php
index 35e6e9b..9cc1296 100644
--- a/lib/Machine.lib.php
+++ b/lib/Machine.lib.php
@@ -281,17 +281,22 @@ class Machine implements JsonSerializable {
 
     /**
      * Generate a random ID number that is not in use.
-     * Default: 680[1-3]######
+     * Default: 680#####[check digit]
      * @global $database
      * @param int $min Optional minimum number.
      * @param int $max Optional maximum number.
      * @return int
      */
-    public static function generateId(int $min = 680100000, int $max = 680399999): int {
+    public static function generateId(int $min = 68010000, int $max = 68099999): int {
         global $database;
 
         do {
             $id = random_int($min, $max);
+
+            // If default gen add check digit
+            if ($id >= 68010000 && $id <= 68039999) {
+                $id = ("$id" . CheckDigit::S10($id)) * 1;
+            }
         } while ($database->has('machines', ['machineid' => $id]) || $database->has('components', ['compid' => $id]));
 
         return $id;
diff --git a/public/index.php b/public/index.php
index 47e7538..dca2225 100644
--- a/public/index.php
+++ b/public/index.php
@@ -36,7 +36,36 @@ if (isset($_GET["backgroundcolor"]) && !empty($_GET["backgroundcolor"]) && preg_
     <div class="row justify-content-center">
         <div class="<?php if (!isset($_GET["embed"])) { ?>col-12 col-md-8<?php } else { ?>col-12<?php } ?>">
             <?php
-            if (empty($_GET["id"]) || (!Machine::exists($_GET["id"]) && !Machine::serialExists($_GET["id"]))) {
+            if (!empty($_GET["id"]) && strpos($_GET["id"], "68") === 0 && !CheckDigit::validateS10($_GET["id"])) {
+                // Made a typo in the machine ID
+                ?>
+                <div class="card">
+                    <h3 class="card-header d-flex">
+                        <div>
+                            <i class="fas fa-desktop"></i> <?php $Strings->get("Device Info"); ?>
+                        </div>
+                    </h3>
+                    <div class="card-body">
+                        <?php
+                        if (!empty($_GET["id"])) {
+                            ?>
+                            <p class="text-danger"><code><?php echo htmlspecialchars($_GET['id']); ?></code> is not valid. Please try re-typing it.</p>
+                            <?php
+                        }
+                        ?>
+                        <?php if (!isset($_GET["embed"])) { ?>
+                            <p>
+                                Enter a <?php echo $SETTINGS["branding"]["machineidnumber"]; ?>, serial number, or tracking code.
+                            </p>
+                            <form method="GET">
+                                <input type="text" name="id" class="form-control" placeholder="Number" required />
+                                <button type="submit" class="btn btn-primary btn-block mt-2">Get Info</button>
+                            </form>
+                        <?php } ?>
+                    </div>
+                </div>
+                <?php
+            } else if (empty($_GET["id"]) || (!Machine::exists($_GET["id"]) && !Machine::serialExists($_GET["id"]))) {
                 // try package tracking query
                 $trackingok = false;
                 if (!empty($_GET["id"]) && preg_match("/^[a-z0-9]{10,}$/", $_GET["id"])) {