From 08b2ba0ca7cc8a5cac9d0cb50eb9cb0edce4f245 Mon Sep 17 00:00:00 2001
From: Tim Otten <totten@civicrm.org>
Date: Fri, 18 Dec 2020 18:03:21 -0800
Subject: [PATCH] CRM_Utils_String - Add URL-style base64 codec

---
 CRM/Utils/String.php                   | 25 +++++++++++++++++++++++++
 tests/phpunit/CRM/Utils/StringTest.php | 13 +++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/CRM/Utils/String.php b/CRM/Utils/String.php
index 7c08974365..8e761a5be8 100644
--- a/CRM/Utils/String.php
+++ b/CRM/Utils/String.php
@@ -221,6 +221,31 @@ class CRM_Utils_String {
     }
   }
 
+  /**
+   * Encode string using URL-safe Base64.
+   *
+   * @param string $v
+   *
+   * @return string
+   * @see https://tools.ietf.org/html/rfc4648#section-5
+   */
+  public static function base64UrlEncode($v) {
+    return rtrim(str_replace(['+', '/'], ['-', '_'], base64_encode($v)), '=');
+  }
+
+  /**
+   * Decode string using URL-safe Base64.
+   *
+   * @param string $v
+   *
+   * @return false|string
+   * @see https://tools.ietf.org/html/rfc4648#section-5
+   */
+  public static function base64UrlDecode($v) {
+    // PHP base64_decode() is already forgiving about padding ("=").
+    return base64_decode(str_replace(['-', '_'], ['+', '/'], $v));
+  }
+
   /**
    * Determine the string replacements for redaction.
    * on the basis of the regular expressions
diff --git a/tests/phpunit/CRM/Utils/StringTest.php b/tests/phpunit/CRM/Utils/StringTest.php
index be31cfa8d0..dcc461568c 100644
--- a/tests/phpunit/CRM/Utils/StringTest.php
+++ b/tests/phpunit/CRM/Utils/StringTest.php
@@ -10,6 +10,19 @@ class CRM_Utils_StringTest extends CiviUnitTestCase {
     parent::setUp();
   }
 
+  public function testBase64Url() {
+    $examples = [
+      'a' => 'YQ',
+      'ab' => 'YWI',
+      'abc' => 'YWJj',
+      '3f>' => 'M2Y-',
+    ];
+    foreach ($examples as $raw => $b64) {
+      $this->assertEquals($b64, CRM_Utils_String::base64UrlEncode($raw));
+      $this->assertEquals($raw, CRM_Utils_String::base64UrlDecode($b64));
+    }
+  }
+
   public function testStripPathChars() {
     $testSet = [
       '' => '',
-- 
2.25.1