added skip option

Author: 256dpi

README.md

@@ -151,11 +151,12 @@ void setOptions(int keepAlive, bool cleanSession, int timeout);
 Connect to broker using the supplied client id and an optional username and password:
 
 ```c++
-bool connect(const char clientId[]);
-bool connect(const char clientId[], const char username[]);
-bool connect(const char clientId[], const char username[], const char password[]);
+bool connect(const char clientId[], bool skip = false);
+bool connect(const char clientId[], const char username[], bool skip = false);
+bool connect(const char clientId[], const char username[], const char password[], bool skip = false);
 ```
 
+- If the `skip` option is set to true, the client skip the network level connection and continue with the MQTT level connection. This option should can be used in order to establish and verify TLS connections. 
 - This functions returns a boolean that indicates if the connection has been established successfully.
 
 Publishes a message to the broker with an optional payload:

src/MQTTClient.h

@@ -273,22 +273,25 @@ class MQTTClient {
     this->timeout = (uint32_t)timeout;
   }
 
-  bool connect(const char clientId[]) { return this->connect(clientId, nullptr, nullptr); }
+  bool connect(const char clientId[], bool skip = false) { return this->connect(clientId, nullptr, nullptr); }
 
-  bool connect(const char clientId[], const char username[]) { return this->connect(clientId, username, nullptr); }
+  bool connect(const char clientId[], const char username[], bool skip = false) { return this->connect(clientId, username, nullptr); }
 
-  bool connect(const char clientId[], const char username[], const char password[]) {
+  bool connect(const char clientId[], const char username[], const char password[], bool skip = false) {
     // close left open connection if still connected
-    if (this->connected()) {
+    if (!skip && this->connected()) {
       this->close();
     }
 
     // save client
     this->network.client = this->netClient;
 
-    // connect to host
-    if (this->netClient->connect(this->hostname, (uint16_t)this->port) <= 0) {
-      return false;
+    // connect to hostg
+    if(!skip) {
+      int ret = this->netClient->connect(this->hostname, (uint16_t)this->port);
+      if (ret <= 0) {
+        return false;
+      }
     }
 
     // prepare options