add implementation of random_int for pre-PHP7

booking.earlyaccess_admin.inc

@@ -103,25 +103,6 @@ function booking_earlyaccess_generate_codes() {
   return t("Created $num_codes_to_add early access codes.");
 }
 
-/**
- * Function to calculate unique code
- * @see https://stackoverflow.com/questions/1846202/php-how-to-generate-a-random-unique-alphanumeric-string
- * Requires PHP7
- */
-function booking_getToken($length) {
-  $token = "";
-  $codeAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
-  //$codeAlphabet.= "abcdefghijklmnopqrstuvwxyz";
-  $codeAlphabet.= "0123456789";
-  $max = strlen($codeAlphabet); // edited
-
-  for ($i=0; $i < $length; $i++) {
-    $token .= $codeAlphabet[random_int(0, $max-1)];
-  }
-
-  return $token;
-}
-
 /**
  * Function to generate csv of early access codes for the current event
  */
@@ -182,3 +163,70 @@ function booking_earlyaccess_csv_report() {
 	print $csv;
   exit(0);
 }
+
+/**
+ * Function to calculate unique code
+ * @see https://stackoverflow.com/questions/1846202/php-how-to-generate-a-random-unique-alphanumeric-string
+ * Requires PHP7
+ */
+ function booking_getToken($length) {
+  $token = "";
+  $codeAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+  //$codeAlphabet.= "abcdefghijklmnopqrstuvwxyz";
+  $codeAlphabet.= "0123456789";
+  $max = strlen($codeAlphabet); // edited
+
+  if (!function_exists('random_int')) {
+    function random_int($min, $max) {
+        if (!function_exists('mcrypt_create_iv')) {
+            trigger_error(
+                'mcrypt must be loaded for random_int to work', 
+                E_USER_WARNING
+            );
+            return null;
+        }
+        
+        if (!is_int($min) || !is_int($max)) {
+            trigger_error('$min and $max must be integer values', E_USER_NOTICE);
+            $min = (int)$min;
+            $max = (int)$max;
+        }
+        
+        if ($min > $max) {
+            trigger_error('$max can\'t be lesser than $min', E_USER_WARNING);
+            return null;
+        }
+        
+        $range = $counter = $max - $min;
+        $bits = 1;
+        
+        while ($counter >>= 1) {
+            ++$bits;
+        }
+        
+        $bytes = (int)max(ceil($bits/8), 1);
+        $bitmask = pow(2, $bits) - 1;
+  
+        if ($bitmask >= PHP_INT_MAX) {
+            $bitmask = PHP_INT_MAX;
+        }
+  
+        do {
+            $result = hexdec(
+                bin2hex(
+                    mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM)
+                )
+            ) & $bitmask;
+        } while ($result > $range);
+  
+        return $result + $min;
+    }
+  }  
+
+  for ($i=0; $i < $length; $i++) {
+    $token .= $codeAlphabet[random_int(0, $max-1)];
+  }
+
+  return $token;
+}
+