From cf4c92b7bff94e4aad842099a6c2387a8510c036 Mon Sep 17 00:00:00 2001
From: Dominique Fournier <dominique@fournier38.fr>
Date: Mon, 11 May 2020 20:29:13 +0000
Subject: [PATCH] ipaddresses : Add cidr2netmask method for IPv4 masks

git-svn-id: https://svn.fournier38.fr/svn/ProgSVN/trunk@5989 bf3deb0d-5f1a-0410-827f-c0cc1f45334c
---
 Tests/ipaddressesTest.php | 34 ++++++++++++++++++++++++++++++++++
 ipaddresses.php           | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/Tests/ipaddressesTest.php b/Tests/ipaddressesTest.php
index d72fded..40b370b 100644
--- a/Tests/ipaddressesTest.php
+++ b/Tests/ipaddressesTest.php
@@ -396,6 +396,40 @@ class ipaddressesTest extends PHPUnit_Framework_TestCase
     $this->assertSame (0, $res);
   }
 
+  public function test_cidr2netmask_1 ()
+  {
+    $i = new ipaddresses ();
+    $res = $i->cidr2netmask (0, true);
+    $this->assertSame ("0.0.0.0", $res);
+  }
+
+  public function test_cidr2netmask_2 ()
+  {
+    $i = new ipaddresses ();
+    $res = $i->cidr2netmask (24, true);
+    $this->assertSame ("255.255.255.0", $res);
+  }
+
+  public function test_cidr2netmask_3 ()
+  {
+    $i = new ipaddresses ();
+    $res = $i->cidr2netmask (25, true);
+    $this->assertSame ("255.255.255.128", $res);
+  }
+
+  public function test_cidr2netmask_4 ()
+  {
+    $i = new ipaddresses ();
+    $res = $i->cidr2netmask (32, true);
+    $this->assertSame ("255.255.255.255", $res);
+  }
+  public function test_cidr2netmask_5 ()
+  {
+    $i = new ipaddresses ();
+    $res = $i->cidr2netmask (1, true);
+    $this->assertSame ("128.0.0.0", $res);
+  }
+
   public function test_ipInNetwork1 ()
   {
     $i = new ipaddresses ();
diff --git a/ipaddresses.php b/ipaddresses.php
index c6ca209..9482f24 100644
--- a/ipaddresses.php
+++ b/ipaddresses.php
@@ -521,6 +521,41 @@ class ipaddresses
   }
   // }}}
 
+  /** This function return the netmask associated to a CIDR.
+    * Work only on IPv4 addresses (CIDR between 0 and 32)
+    * @param string $cidr The CIDR to convert in netmask
+    * @param boolean|null $maskdirect If true return a direct mask, if false
+    * return a wildcard mask
+    * @return the mask
+    * @return false if the CIDR is not between 0 and 32
+    */
+  public function cidr2netmask ($cidr, $maskdirect = true)
+  // {{{
+  {
+    if ($cidr < 0 || $cidr > 32)
+      return false;
+    $maskdirect = "". ($maskdirect + 0);
+    $maskrevert = ($maskdirect === "0") ? "1" : "0";
+    $bin = "";
+    for ($i = 0 ; $i < 32 ; $i++)
+    {
+      if ($i < $cidr)
+        $bin .= $maskdirect;
+      else
+        $bin .= $maskrevert;
+    }
+    $res = "";
+    for ($i = 0 ; $i < 32 ; $i = $i + 8)
+    {
+      $block = substr ($bin, $i, 8);
+      if ($i > 0)
+        $res .= ".";
+      $res .= bindec ($block);
+    }
+    return $res;
+  }
+  // }}}
+
   /** This function return true if the provided address is in the provided
     * network with the associated cidr
     * @param string $ip The IPv4 or IPv6 to test