Cant send the connect packet data to the broker.

[user25677]

Hi guys,

             Im writing a C program to connect the mosquitto broker via GPRS/GSM Modem. I almost written a code to connect the mosquitto broker. I think we have to format the correct packet to connect with broker. I formed the packet format, but can't send the data to the broker. I've installed wireshark protocol analyser in broker machine. After run this code wireshark shows something happend from my modem to broker, but packet length and "MQIsdp" data not showing in the wireshark protocol analyser. Whats wrong in the code?  Below find the code and also i've attached the serial.h header file

Thanks

#include <stdio.h>

#include <time.h>

#include "serial.h"

#include "connpack.h"

#include <stdlib.h>

#include <string.h>

#include <stdint.h>

#include <inttypes.h>

#define A "AT\r"

#define B "AT+CPIN?\r"

#define C "AT+CREG?\r"

#define D "AT+CGATT?\r"

#define E "AT+CIPSHUT\r"

#define X "AT+CIPSTATUS\r"

#define G "AT+CIPMUX=0\r"

#define H "AT+CSTT=\"xxxx\",\"xxxx\",\"xxxx\"\r"

#define I "AT+CIICR\r"

#define J "AT+CIFSR\r"

#define K "AT+CIPSTART=\"TCP\",\"xxx.xxx.xxx.xxx\",\"xxxx\"\r"

#define L "AT+CIPSEND\r"

char* ATC[]={A,B,C,D,E,X,G,H,I,J,K,L};

#define MQTTCONNECT 1<<4

#define MQTTPUBLISH 3<<4

#define KEEPALIVE 15000

int main()

{

char *id="CONMQTT";

int i,j;

port_open();

uint16_t buffer[255];

uint16_t buf[255];

for(i=0;i<=11;i++)

{

port_write(ATC[i]);

sleep(5);

printf("%s\n",port_read());

if(i==11)

{

char *id="MQTT";

   uint8_t var_header[] = {0x00,0x06, 0x4d, 0x51, 0x49, 0x73, 0x64, 0x70, 0x03, 0x02, 0x00, KEEPALIVE/500, 0x00, strlen(id)};

   uint8_t fixed_header[] = {MQTTCONNECT, 12+strlen(id)+2};

   char packet[sizeof(fixed_header)+sizeof(var_header)+strlen(id) + 2];

   char connectdatalen=2+12+2+strlen(id);

    uint8_t packetlen = 2 + connectdatalen;

   memset(packet, 0, sizeof(packet));

   memcpy(packet, fixed_header, sizeof(fixed_header));

   memcpy(packet+sizeof(fixed_header), var_header, sizeof(var_header));

   memcpy(packet+sizeof(fixed_header)+sizeof(var_header),id,strlen(id));

 

       for(i=0;i<=packetlen;i++)

       {

        //putchar(packet[i]);

        sprintf(buf, "%c\x1A", packet[i]);

        port_write(buf);

       

       }

}

}

return 0;

}

[Roger Light]

Hi Mahesh,

This mailing list is for the discussion of the protocol, not
programming problems.

The answer to your problem is that your port_write() function uses
strlen() to determine the length of data to write, but your binary
data contains a 0, so the write will be truncated at that point. You
need to pass a length parameter to port_write() so it knows how much
data to write. Don't use strlen.

This is what I was referring to in my comments on your stackoverflow question:

http://stackoverflow.com/questions/30979182/mosquitto-broker-is-receving-data-partially/

Cheers,

Roger

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[user25677]

Hi Roger Light, 

                          I've sucessfully send it in Arduino. Have to read the C little deeper. Hope i will get the solution for it. Thanks Light. Learn useful info from you.