Re: [mosquitto-dev] Question about publishing to an MQTT brokerusing TLS

["Mark Pilant" <lpilant@xxxxxxxxxx>]

Hi Roger.

I did call mosquitto_lib_init(). Since the test program isn't very long I've included it below.

I included the sleep() call because I thought the callbacks would be called asynchronously, and wanted to see if I was actually getting the connect completion before doing the publish. I notice pub_client.c actually does the mosquitto_publish from within the connect callback. I expect I'll so something similar to avoid races, but I didn't make that change because I noticed the connect wasn't completing.

- Mark

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#include <stdio.h>
#include <string.h>

#include <mosquitto.h>

#define cafile "./rootCA.pem"
#define certfile "./cert.pem"
#define keyfile "./private-key.pem"
#define host "the-mqtt-broker.com"
#define port 8883
#define qos 0
#define topic "topic/test"
#define message "{\"msg\" : \"Hello ... World\"}"

void connect_callback(struct mosquitto *mosq, void *obj, int result) {
printf("Connect callback: \n");
}

void disconnect_callback(struct mosquitto *mosq, void *obj, int rc) {
printf("Disconnect callback: \n");
}

void log_callback(struct mosquitto *mosq, void *obj, int level, const char *str) {
printf("%s\n", str);
}

void publish_callback(struct mosquitto *mosq, void *obj, int mid) {
printf("Publish callback: \n");
}

int main (int argc, char *argv[]) {
char idstr[64];
struct mosquitto *mosq = NULL;
// int mqtt_version = 3; /* MQTT_PROTOCOL_V31 */
int mqtt_version = 4; /* MQTT_PROTOCOL_V311 */
int status;

/* Initialize needed storage. */
snprintf(idstr, sizeof(idstr), "mosquitto_%d", getpid());

/* Initialize mosquitto. */
mosquitto_lib_init();

/* Create a new mosquitto instance. */
mosq = mosquitto_new(idstr, true, NULL);
if (!mosq) {
printf("Error creating mosquitto instance\n");
return 1;
}
printf("New mosquitto instance created\n");

/* Connect up all the callback functions. */
mosquitto_log_callback_set(mosq, log_callback);
mosquitto_connect_callback_set(mosq, connect_callback);
mosquitto_disconnect_callback_set(mosq, disconnect_callback);
mosquitto_publish_callback_set(mosq, publish_callback);
printf("Callback setup complete\n");

/* Use TLS for communications. */
status = mosquitto_tls_set(mosq, cafile, NULL,
certfile, keyfile, NULL);
if (status) {
printf("Error (%d) configuring TLS.\n", status);
return 2;
}
printf("TLS setup complete\n");

/* Maximum inflight messages. */
status = mosquitto_max_inflight_messages_set(mosq, 20);
if (status) {
printf("Error (%d) setting max inflight message count.\n", status);
return 6;
}
printf("Max inflight count set\n");

/* Set mosquitto options. */
status = mosquitto_opts_set(mosq, MOSQ_OPT_PROTOCOL_VERSION,
&mqtt_version);
if (status) {
printf("Error (%d) setting mosquitto options.\n", status);
return 7;
}
printf("Mosquitto options set\n");

/* Connect to the broker. */
status = mosquitto_connect_bind(mosq, host, port, 60, NULL);
if (status) {
printf("Error (%d) connecting to broker.\n", status);
return 3;
}

sleep(1000);

/* Publish the message */
status = mosquitto_publish(mosq, NULL, topic,
strlen(message), message,
qos, false);
if (status) {
printf("Error (%d) publishing message.\n", status);
return 4;
}

return 0;
}