How to add function for mqtt server authentication - c

Question

How can I add the functions for username and password to authen mqtt broker.
The original file has not section for authentication. How can I adding function for username and password in authentication mqtt server?
This file has mqtt.h that is sitting parameters (such as hotsname, port, etc.). and I have added parameter for username and password in mqtt.h following this
struct mqtt_handle_s {
// Public members
char *host;
int port;
char *username;
char *password;
char *client_id;
mqtt_on_connect_t on_connect;
mqtt_on_message_t on_message;
// Private members
struct mosquitto *client;
char *topic_list;
size_t topic_size;
};
and then how can I adding the function for running that parameter to using in mqtt server authentication?
the main code is following..
#mqtt.c full code.
#if defined(_WIN32)
#include <windows.h>
#endif
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include "app_log.h"
#include "mqtt.h"
// Check if libmosquitto version is at least 1.5.7
#if LIBMOSQUITTO_VERSION_NUMBER < 1005007
#warning Untested libmosquitto version!
#endif
#define QOS 1
#define KEEPALIVE_INTERVAL_SEC 30
#define LOOP_TIMEOUT_MS 1
#define LOG_MASK MOSQ_LOG_NONE
static void mqtt_on_connect(struct mosquitto *mosq, void *obj, int rc);
static void mqtt_on_disconnect(struct mosquitto *mosq, void *obj, int rc);
static void mqtt_on_message(struct mosquitto *mosq, void *obj, const struct mosquitto_message *message);
static void mqtt_on_log(struct mosquitto *mosq, void *obj, int level, const char *str);
static const char * mqtt_err2str(int rc);
mqtt_status_t mqtt_init(mqtt_handle_t *handle)
{
mqtt_status_t ret = MQTT_SUCCESS;
int rc = MOSQ_ERR_ERRNO; // return code if mosquitto_new() fails
struct mosquitto *mosq;
mosquitto_lib_init();
mosq = mosquitto_new(handle->client_id, true, handle);
if (mosq != NULL) {
mosquitto_connect_callback_set(mosq, mqtt_on_connect);
mosquitto_disconnect_callback_set(mosq, mqtt_on_disconnect);
mosquitto_message_callback_set(mosq, mqtt_on_message);
mosquitto_log_callback_set(mosq, mqtt_on_log);
rc = mosquitto_connect(mosq, handle->host, handle->port, KEEPALIVE_INTERVAL_SEC);
}
if (rc != MOSQ_ERR_SUCCESS) {
app_log("MQTT init failed: '%s'\n", mqtt_err2str(rc));
ret = MQTT_ERROR_CONNECT;
handle->client = NULL;
if (mosq != NULL) {
mosquitto_destroy(mosq);
}
} else {
handle->client = mosq;
}
handle->topic_list = NULL;
handle->topic_size = 0;
return ret;
}
mqtt_status_t mqtt_publish(mqtt_handle_t *handle, const char *topic, const char *payload)
{
mqtt_status_t ret = MQTT_SUCCESS;
int rc;
int mid;
if (handle->client != NULL) {
rc = mosquitto_publish(handle->client, &mid, topic, strlen(payload), payload, QOS, false);
if (rc != MOSQ_ERR_SUCCESS) {
app_log("MQTT publish attempt failed: '%s'\n", mqtt_err2str(rc));
ret = MQTT_ERROR_PUBLISH;
}
} else {
ret = MQTT_ERROR_PUBLISH;
}
return ret;
}
mqtt_status_t mqtt_step(mqtt_handle_t *handle)
{
mqtt_status_t ret = MQTT_SUCCESS;
int rc;
if (handle->client != NULL) {
rc = mosquitto_loop(handle->client, LOOP_TIMEOUT_MS, 1);
if (rc != MOSQ_ERR_SUCCESS) {
app_log("MQTT loop failed: '%s'\n", mqtt_err2str(rc));
ret = MQTT_ERROR_STEP;
}
} else {
ret = MQTT_ERROR_STEP;
}
return ret;
}
mqtt_status_t mqtt_subscribe(mqtt_handle_t *handle, const char *topic)
{
mqtt_status_t ret = MQTT_SUCCESS;
int rc;
size_t topic_size;
if (handle->client != NULL) {
// Try to subscribe to topic.
rc = mosquitto_subscribe(handle->client, NULL, topic, QOS);
if ((rc != MOSQ_ERR_SUCCESS) && (rc != MOSQ_ERR_NO_CONN)) {
app_log("MQTT subscribe attempt failed to topic '%s': '%s'\n", topic, mqtt_err2str(rc));
ret = MQTT_ERROR_SUBSCRIBE;
}
// Append topic to topic list.
topic_size = strlen(topic) + 1;
handle->topic_list = realloc(handle->topic_list, handle->topic_size + topic_size);
if (handle->topic_list == NULL) {
app_log("MQTT failed to append topic to topic list.\n");
ret = MQTT_ERROR_SUBSCRIBE;
} else {
strcpy(&handle->topic_list[handle->topic_size], topic);
handle->topic_size += topic_size;
}
} else {
ret = MQTT_ERROR_SUBSCRIBE;
}
return ret;
}
mqtt_status_t mqtt_deinit(mqtt_handle_t *handle)
{
int rc;
if (handle->client != NULL) {
rc = mosquitto_disconnect(handle->client);
if (rc != MOSQ_ERR_SUCCESS) {
app_log("MQTT failed to disconnect: '%s', continue deinit.\n", mqtt_err2str(rc));
}
mosquitto_destroy(handle->client);
mosquitto_lib_cleanup();
if (handle->topic_list != NULL) {
free(handle->topic_list);
}
}
return MQTT_SUCCESS;
}
static void mqtt_on_connect(struct mosquitto *mosq, void *obj, int rc)
{
mqtt_handle_t *handle = (mqtt_handle_t *)obj;
size_t topic_start = 0;
char *topic;
int ret = MOSQ_ERR_SUCCESS;
app_log("MQTT connect status '%s'\n", mosquitto_connack_string(rc));
if (rc == 0) {
if (handle->on_connect != NULL) {
handle->on_connect(handle);
}
while (topic_start < handle->topic_size) {
topic = &handle->topic_list[topic_start];
ret = mosquitto_subscribe(mosq, NULL, topic, QOS);
topic_start += strlen(topic) + 1;
if (ret != MOSQ_ERR_SUCCESS) {
app_log("MQTT subscribe attempt failed to topic '%s': '%s'\n", topic, mqtt_err2str(ret));
}
}
}
}
static void mqtt_on_disconnect(struct mosquitto *mosq, void *obj, int rc)
{
int ret;
app_log("MQTT disconnected with reason '%d'\n", rc);
if (rc != 0) {
ret = mosquitto_reconnect(mosq);
app_log("MQTT reconnection attempt with status '%s'\n", mqtt_err2str(ret));
}
}
static void mqtt_on_message(struct mosquitto *mosq, void *obj, const struct mosquitto_message *message)
{
mqtt_handle_t *handle = (mqtt_handle_t *)obj;
char *payload;
if (handle->on_message != NULL) {
payload = malloc(message->payloadlen + 1);
if (NULL == payload) {
app_log("MQTT failed to allocate payload buffer.\n");
} else {
memcpy(payload, message->payload, message->payloadlen);
// Make sure that payload is NULL terminated.
payload[message->payloadlen] = 0;
handle->on_message(handle, message->topic, payload);
free(payload);
}
}
}
static void mqtt_on_log(struct mosquitto *mosq, void *obj, int level, const char *str)
{
if (level & LOG_MASK) {
app_log("MQTT log (%d): %s\n", level, str);
}
}
#if defined(_WIN32)
static const char * mqtt_err2str(int rc)
{
char *ret = NULL;
static char err_str[256];
if (MOSQ_ERR_ERRNO == rc) {
// Make sure to have a default output if FormatMessage fails
// or if error code is not available in errno.
strncpy(err_str, "Unknown system error", sizeof(err_str));
if (errno != 0) {
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, // dwFlags
NULL, // lpSource
errno, // dwMessageId
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // dwLanguageId
err_str, // lpBuffer
sizeof(err_str), // nSize
NULL); // Arguments
}
// Make sure that err_str is NULL terminated.
err_str[sizeof(err_str) - 1] = 0;
ret = err_str;
} else {
ret = (char *)mosquitto_strerror(rc);
}
return ret;
}
#else
static const char * mqtt_err2str(int rc)
{
return (MOSQ_ERR_ERRNO == rc) ? strerror(errno) : mosquitto_strerror(rc);
}
#endif // _WIN32