feat(C): Add paho TLS example

Signed-off-by: Moi Ran <[email protected]>

Author: RanMaoyi

mqtt-client-C-paho/main_tls.c

@@ -0,0 +1,88 @@
+#include "stdlib.h"
+#include "string.h"
+#include "unistd.h"
+#include "MQTTClient.h"
+
+#define ADDRESS     "ssl://127.0.0.1:8883"
+#define USERNAME    "emqx"
+#define PASSWORD    "public"
+#define CLIENTID    "c-client"
+#define QOS         0
+#define TOPIC       "emqx/c-test"
+#define TIMEOUT     10000L
+#define CLIENTCERT  "/etc/emqx/certs/client-cert.pem"
+#define CACERT      "/etc/emqx/certs/cacert.pem"
+#define PRIVATEKEY  "/etc/emqx/certs/client-key.pem"
+
+void publish(MQTTClient client, char *topic, char *payload) {
+    MQTTClient_message message = MQTTClient_message_initializer;
+    message.payload = payload;
+    message.payloadlen = strlen(payload);
+    message.qos = QOS;
+    message.retained = 0;
+    MQTTClient_deliveryToken token;
+    MQTTClient_publishMessage(client, topic, &message, &token);
+    MQTTClient_waitForCompletion(client, token, TIMEOUT);
+    printf("Send `%s` to topic `%s` \n", payload, TOPIC);
+}
+
+int on_message(void *context, char *topicName, int topicLen, MQTTClient_message *message) { char *payload = message->payload;
+    printf("Received `%s` from `%s` topic \n", payload, topicName);
+    MQTTClient_freeMessage(&message);
+    MQTTClient_free(topicName);
+    return 1;
+}
+
+int main(int argc, char *argv[]) {
+    int rc;
+    MQTTClient client;
+
+	MQTTClient_createOptions createOpts = MQTTClient_createOptions_initializer;
+    MQTTClient_create(&client, ADDRESS, CLIENTID, 0, NULL);
+    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
+    conn_opts.username = USERNAME;
+    conn_opts.password = PASSWORD;
+
+	MQTTClient_SSLOptions ssl_opts = MQTTClient_SSLOptions_initializer;
+	/*
+	 * Set the value of 'verify' to 0, which means
+	 * that the domain should not be checked.
+	 * Otherwise, if the domain does not match,
+	 * an error will occur.
+	 */
+	ssl_opts.verify = 0;
+	ssl_opts.trustStore = CACERT;
+	/*
+	 * Two-Way SSL Authentiacation needed.
+	 * If you want to use One-Way SSL Authentication,
+	 * please comment out keyStore and privateKey.
+	 */
+	ssl_opts.privateKey = PRIVATEKEY;
+	ssl_opts.keyStore = CLIENTCERT;
+	/*
+	 * Notice: In higher versions of openssl
+	 * the SSL/TLS version is depended on openssl itself.
+	 * (Paho will use TLS_Client_method(), more details please see openssl docs)
+	 */
+	conn_opts.ssl = &ssl_opts;
+
+    MQTTClient_setCallbacks(client, NULL, NULL, on_message, NULL);
+    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) {
+        printf("Failed to connect, return code %d\n", rc);
+        exit(-1);
+    } else {
+        printf("Connected to MQTT Broker!\n");
+    }
+    // subscribe topic
+    MQTTClient_subscribe(client, TOPIC, QOS);
+    char payload[16];
+    for (int i = 0; i < 100; i += 1) {
+        // publish message to broker
+        snprintf(payload, 16, "message-%d", i);
+        publish(client, TOPIC, payload);
+        sleep(1);
+    }
+    MQTTClient_disconnect(client, TIMEOUT);
+    MQTTClient_destroy(&client);
+    return rc;
+}