libmosquitto example

lobmosq.c

/*
  needs libmosquitto-dev
  $ gcc -o libmosq libmosq.c -lmosquitto
*/
#include <stdio.h>
#include <mosquitto.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void mosq_log_callback(struct mosquitto *mosq, void *userdata, int level, const char *str)
{
	/* Pring all log messages regardless of level. */
  
  switch(level){
    //case MOSQ_LOG_DEBUG:
    //case MOSQ_LOG_INFO:
    //case MOSQ_LOG_NOTICE:
    case MOSQ_LOG_WARNING:
    case MOSQ_LOG_ERR: {
      printf("%i:%s\n", level, str);
    }
  }
  
	
}

struct mosquitto *mosq = NULL;
char *topic = NULL;
void mqtt_setup(){

	char *host = "localhost";
	int port = 1883;
	int keepalive = 60;
	bool clean_session = true;
  topic = "/testtopic";
  
  mosquitto_lib_init();
  mosq = mosquitto_new(NULL, clean_session, NULL);
  if(!mosq){
		fprintf(stderr, "Error: Out of memory.\n");
		exit(1);
	}
  
  mosquitto_log_callback_set(mosq, mosq_log_callback);
  
  if(mosquitto_connect(mosq, host, port, keepalive)){
		fprintf(stderr, "Unable to connect.\n");
		exit(1);
	}
  int loop = mosquitto_loop_start(mosq);
  if(loop != MOSQ_ERR_SUCCESS){
    fprintf(stderr, "Unable to start loop: %i\n", loop);
    exit(1);
  }
}

int mqtt_send(char *msg){
  return mosquitto_publish(mosq, NULL, topic, strlen(msg), msg, 0, 0);
}

int main(int argc, char *argv[])
{
  mqtt_setup();
  int i = -1000;
  char *buf = malloc(64);
  while(1){
    sprintf(buf,"i=%i",i++);
    int snd = mqtt_send(buf);
    if(snd != 0) printf("mqtt_send error=%i\n", snd);
    usleep(100000);
  }
}

how to subscribe?

looks like

message_callback

hm...

do you know good example?

official docs seems suxx

looks better example: https://gist.github.com/evgeny-boger/8cefa502779f98efaf24