Added fix for php 7.1+

Author: byrnedo

src/Nats/Connection.php

@@ -1,6 +1,7 @@
 <?php
 namespace Nats;
 
+use PhpSpec\CodeGenerator\Generator\GeneratorInterface;
 use RandomLib\Factory;
 use RandomLib\Generator;
 
@@ -115,7 +116,7 @@ public function getSubscriptions()
     private $streamSocket;
 
     /**
-     * @var Generator
+     * @var Generator|Php71RandomGenerator
      */
     private $randomGenerator;
 
@@ -130,8 +131,12 @@ public function __construct(ConnectionOptions $options = null)
         $this->pubs = 0;
         $this->subscriptions = [];
         $this->options = $options;
-        $randomFactory = new Factory();
-        $this->randomGenerator = $randomFactory->getLowStrengthGenerator();
+        if(version_compare(phpversion(), '7.0', '>')){
+            $this->randomGenerator = new Php71RandomGenerator();
+        } else {
+            $randomFactory = new Factory();
+            $this->randomGenerator = $randomFactory->getLowStrengthGenerator();
+        }
 
         if (is_null($options)) {
             $this->options = new ConnectionOptions();

src/Nats/Php71RandomGenerator.php

@@ -0,0 +1,19 @@
+<?php
+
+
+namespace Nats;
+
+
+
+class Php71RandomGenerator
+{
+    /**
+     * A simple wrapper on random_bytes
+     *
+     * @param $len
+     * @return string
+     */
+    public function generateString($len) {
+        return bin2hex(random_bytes($len));
+    }
+}