Re: [mosquitto-dev] Possible Bug in in ping handling

[mosquitto-dev.gpbenton@xxxxxxxx]

Hi Roger,

The line

system("mosquitto_pub -t /test -m Off");

is simulating what is happening to my client.  A completely separate
client is sending a publish, which my client accepts, but then causes my
client to re-connect some time later.

I cannot control when this other client publishes , so my client
re-connects randomly throughout the day.  My client does not normally
publish messages.

The example code publishes (from a completely separate client, as you
say) about 3 seconds before the receiving client is due to generate a
ping, which seems to reproduce the symptoms every time.

I hope that makes the situation clearer.

Regards

Graham



On 22/02/2016 14:48, Roger Light - roger@xxxxxxxxxx wrote:
> Hi Graham,
>
> I'm not quite sure how your code can produce the behaviour you are
> seeing. The line:
>
> system("mosquitto_pub -t /test -m Off");
>
> produces a completely new client that is unrelated to the one you are
> running in your code - and hence wouldn't modify the keepalive timer
> for your client. If you call mosquitto_publish() at that point instead
> you should hopefully not have any further problems.
>
> Cheers,
>
> Roger
>
>
>
> On Sun, Feb 21, 2016 at 3:31 PM,  <mosquitto-dev.gpbenton@xxxxxxxx> wrote:
>> Hi,
>>
>> I believe the program below demonstrates a bug in the ping handling of a
>> client.  It appears that receiving a message just
>> before a ping is expected results in the client sending another
>> connection request.  The result is
>>
>> graham@graham-VirtualBox-k14:~/engMQTTClientTest$ ./clientText
>> Client clientText sending CONNECT
>> Client clientText received CONNACK
>> Client clientText sending SUBSCRIBE (Mid: 1, Topic: /test, QoS: 2)
>> Client clientText received SUBACK
>>
>>
>> Client clientText received PUBLISH (d0, q0, r0, m0, '/test', ... (3 bytes))
>> /test:Off
>> Client clientText sending CONNECT
>> Client clientText received CONNACK
>> Client clientText sending SUBSCRIBE (Mid: 2, Topic: /test, QoS: 2)
>> Client clientText received SUBACK
>> Client clientText received PUBLISH (d0, q0, r0, m0, '/test', ... (3 bytes))
>> /test:Off
>> ^C
>>
>>
>> Of course, I may have misinterpreted something.
>>
>> Regards
>>
>> Graham Benton
>>
>>
>> #include <stdio.h>
>> #include <string.h>
>> #include <time.h>
>> #include <mosquitto.h>
>>
>> enum fail_codes {
>>     ERROR_LOG4C_INIT=1,
>>     ERROR_MOSQ_NEW,
>>     ERROR_MOSQ_CONNECT,
>>     ERROR_MOSQ_LOOP_START,
>>     ERROR_ENER_INIT_FAIL
>> };
>>
>> int countdown = 0;
>>
>> void my_message_callback(struct mosquitto *mosq, void *userdata,
>>                          const struct mosquitto_message *message)
>> {
>>     char tempString[message->payloadlen+1];
>>     strncpy(tempString, message->payload, message->payloadlen);
>>     tempString[message->payloadlen] = '\0';
>>
>>     printf("%s:%s\n", message->topic, tempString);
>> }
>>
>>
>> void my_connect_callback(struct mosquitto *mosq, void *userdata, int result)
>> {
>>
>>     if(!result){
>>         /* Subscribe to broker information topics on successful connect. */
>>         mosquitto_subscribe(mosq, NULL,  "/test", 2);
>>
>>     }else{
>>     printf("Not Connected");
>>     }
>> }
>>
>> void my_log_callback(struct mosquitto *mosq, void *userdata, int level,
>>                      const char *str)
>> {
>>     printf("%s\n", str);
>>
>>     countdown = 17;
>>
>> }
>>
>> int main(int argc, char **argv){
>>     struct mosquitto *mosq = NULL;
>>     int err = 0;
>>
>>
>>
>>     mosquitto_lib_init();
>>     mosq = mosquitto_new("clientText", true, NULL);
>>     if(!mosq){
>>         return ERROR_MOSQ_NEW;
>>     }
>>
>>     mosquitto_log_callback_set(mosq, my_log_callback);
>>     mosquitto_connect_callback_set(mosq, my_connect_callback);
>>     mosquitto_message_callback_set(mosq, my_message_callback);
>>
>>     if((err = mosquitto_connect_async(mosq, "localhost", 1883, 20))
>>        != MOSQ_ERR_SUCCESS){
>>         return ERROR_MOSQ_CONNECT;
>>     }
>>
>>     if ((err = mosquitto_loop_start(mosq)) != MOSQ_ERR_SUCCESS) {
>>         mosquitto_disconnect(mosq);
>>         mosquitto_destroy(mosq);
>>         mosquitto_lib_cleanup();
>>         return ERROR_MOSQ_LOOP_START;
>>     }
>>
>>     while (1) {
>>     sleep(1);
>>     /* Send a message just before the ping is due */
>>     if (--countdown == 0) {
>>         system("mosquitto_pub -t /test -m Off");
>>     }
>>     }
>>
>> }
>>
>>
>>
>> _______________________________________________
>> mosquitto-dev mailing list
>> mosquitto-dev@xxxxxxxxxxx
>> To change your delivery options, retrieve your password, or unsubscribe from this list, visit
>> https://dev.eclipse.org/mailman/listinfo/mosquitto-dev
> _______________________________________________
> mosquitto-dev mailing list
> mosquitto-dev@xxxxxxxxxxx
> To change your delivery options, retrieve your password, or unsubscribe from this list, visit
> https://dev.eclipse.org/mailman/listinfo/mosquitto-dev
>