new: add Tool for random string generation

app/Lib/Tools/RandomTool.php

@@ -0,0 +1,73 @@
+<?php
+
+class RandomTool {
+	public function __construct() {
+		// import compatibility library for PHP < 7.0
+		require_once(APP . 'Lib' . DS . 'random_compat' . DS . 'lib' . DS . 'random.php');
+	}
+
+	/**
+	 * Generate a random string
+	 *
+	 * Generate a random string, using a cryptographically secure
+	 * pseudorandom number generator (random_int)
+	 *
+	 * For PHP 7, random_int is a PHP core function
+	 * For PHP 5.x, depends on https://github.com/paragonie/random_compat
+	 *
+	 * @link https://paragonie.com/b/JvICXzh_jhLyt4y3
+	 *
+	 * @param bool $crypto_secure - If a cryptographically secure or a fast random number generator should be used
+	 * @param int $length - How long should our random string be?
+	 * @param string $charset - A string of all possible characters to choose from
+	 * @return string
+	 */
+	public function random_str($crypto_secure = TRUE, $length = 32, $charset = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')
+	{
+		// Type checks:
+		if (!is_bool($crypto_secure)) {
+			throw new InvalidArgumentException(
+				'random_str - Argument 1 - expected a boolean'
+			);
+		}
+		if (!is_numeric($length)) {
+			throw new InvalidArgumentException(
+				'random_str - Argument 2 - expected an integer'
+			);
+		}
+		if (!is_string($charset)) {
+			throw new InvalidArgumentException(
+				'random_str - Argument 3 - expected a string'
+			);
+		}
+
+		if ($length < 1) {
+			// Just return an empty string. Any value < 1 is meaningless.
+			return '';
+		}
+
+		// Remove duplicate characters from $charset
+		$split = str_split($charset);
+		$charset = implode('', array_unique($split));
+
+		// This is the maximum index for all of the characters in the string $charset
+		$charset_max = strlen($charset) - 1;
+		if ($charset_max < 1) {
+			// Avoid letting users do: random_str($int, 'a'); -> 'aaaaa...'
+			throw new LogicException(
+				'random_str - Argument 3 - expected a string that contains at least 2 distinct characters'
+			);
+		}
+		// Now that we have good data, this is the meat of our function:
+		$random_str = '';
+		for ($i = 0; $i < $length; ++$i) {
+			if ($crypto_secure) {
+				$r = random_int(0, $charset_max);
+			} else {
+				$r = mt_rand(0, $charset_max);
+			}
+			$random_str .= $charset[$r];
+		}
+		return $random_str;
+	}
+}