ipaddresses : Add cidr2netmask method for IPv4 masks

git-svn-id: https://svn.fournier38.fr/svn/ProgSVN/trunk@5989 bf3deb0d-5f1a-0410-827f-c0cc1f45334c

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