Osamu Koizumi / Mbed OS HelloMQTT

HelloMQTT over TLS.

Dependencies:   MQTT

Fork of HelloMQTT by Osamu Koizumi

HelloMQTT over TLS

This program is a fork of HelloMQTT. Added TLS capability by using TLSSocket library. Tested on K64F.

This sample program connects to iot.eclipse.org:8883 by default. Verifies server identification. Subscribes a certain topic. Then publishes three messages with different QoSs, i.e. QoS0, QoS1, and QoS2.

Warning

Some brokers do not accept QoS2 and/or QoS1 message. For example, AWS IoT Message Broker doesn't accept QoS2. In such broker, this program doesn't work as is. Change QoS level.

Output from console

HelloMQTT: version is 0.70

Opening network interface...
Network interface opened successfully.

Connecting to host iot.eclipse.org:8883 ...
Connection established.

MQTT client is trying to connect the server ...
Client connected.

Client is trying to subscribe a topic "mbed-test".
Client has subscribed a topic "mbed-test".

Client publishes messages ...
Publishing message QoS 0.
QoS 0 message published.
! Message arrived: qos 0, retained 0, dup 0, packetid 6257
! Payload Hello World!  QoS 0 message from app version 0.700000

Publishing message QoS 1.
QoS 1 message published.
! Message arrived: qos 1, retained 0, dup 0, packetid 1
! Payload Hello World!  QoS 1 message from app version 0.700000

Publishing message QoS 2.
QoS 2 message published.
! Message arrived: qos 2, retained 0, dup 0, packetid 2
! Payload Hello World!  QoS 2 message from app version 0.700000

Version 0.70: finish 3 msgs

Known Issues

On K64F, when serial baud rate is changed from 9600 to 115200, program fails.

Diff: MQTTNetwork.h

Revision:
24:e7cf8b02e012
Parent:
21:a68bd76740f9
Child:
34:8f7a465c2192
--- a/MQTTNetwork.h	Tue Jan 16 13:41:29 2018 +0000
+++ b/MQTTNetwork.h	Mon Apr 16 18:55:41 2018 +0900
@@ -3,10 +3,23 @@
 
 #include "NetworkInterface.h"
 
+#undef USE_TLS
+#if defined(MBED_CONF_APP_USE_TLS) && (MBED_CONF_APP_USE_TLS == 1)
+  #define USE_TLS
+#endif
+
+#ifdef USE_TLS
+#include "TLSSocket.h"
+#endif /* USE_TLS */
+
 class MQTTNetwork {
 public:
     MQTTNetwork(NetworkInterface* aNetwork) : network(aNetwork) {
+#ifdef USE_TLS
+        socket = new TLSSocket();
+#else
         socket = new TCPSocket();
+#endif /* USE_TLS */
     }
 
     ~MQTTNetwork() {
@@ -21,8 +34,14 @@
         return socket->send(buffer, len);
     }
 
-    int connect(const char* hostname, int port) {
-        socket->open(network);
+    int connect(const char* hostname, int port, const char *ssl_ca_pem = NULL) {
+        nsapi_error_t ret = 0;
+        if((ret = socket->open(network)) != 0) {
+            return ret;
+        }
+#ifdef USE_TLS
+        socket->set_root_ca_pem(ssl_ca_pem);
+#endif /* USE_TLS */
         return socket->connect(hostname, port);
     }
 
@@ -32,7 +51,11 @@
 
 private:
     NetworkInterface* network;
+#ifdef USE_TLS
+    TLSSocket* socket;
+#else
     TCPSocket* socket;
+#endif /* USE_TLS */
 };
 
 #endif // _MQTTNETWORK_H_