Simple usage example of MQTTS library

Dependencies:   EthernetInterface MQTTS NTPClient SDFileSystem mbed-rtos mbed wolfSSL

Fork of HelloMQTT by MQTT

MQTT is light weight protocol for M2M, IoT. MQTTS adds TLS(SSL) security layer into the MQTT. This program shows simple usage example of MQTTS library.

Connect information has to be stored in SD file "connectInfo.txt", with following lines in it.

  • Host Name
  • User Name
  • Password
  • Client ID
  • Topic

The program asks following information on the terminal

  • Port Number to be connected. If the port is >8000 it assumes MQTTS.
  • Message to be published
  • Certificate file name, if MQTTS. Input file name on SD card. Simply Return key force it to no server verification. The program set up the realtime clock by NTP for certificate verification.

This program was tested with FRDM-K64F, against Sango MQTT server by Shiguredo. https://sango.shiguredo.jp/

References:

Linux-example/LinuxIPStack.h

Committer:
wolfSSL
Date:
2015-08-01
Revision:
20:0404c7f31c69
Parent:
8:a3e3113054a1

File content as of revision 20:0404c7f31c69:

#if !defined(LINUX_IPSTACK_H)
#define LINUX_IPSTACK_H

class IPStack 
{
public:    
    IPStack()
    {

    }
    
    int Socket_error(const char* aString)
    {

        if (errno != EINTR && errno != EAGAIN && errno != EINPROGRESS && errno != EWOULDBLOCK)
        {
            if (strcmp(aString, "shutdown") != 0 || (errno != ENOTCONN && errno != ECONNRESET))
                printf("Socket error %s in %s for socket %d\n", strerror(errno), aString, mysock);
        }
        return errno;
    }

    int connect(const char* hostname, int port)
    {
        int type = SOCK_STREAM;
        struct sockaddr_in address;
        int rc = -1;
        sa_family_t family = AF_INET;
        struct addrinfo *result = NULL;
        struct addrinfo hints = {0, AF_UNSPEC, SOCK_STREAM, IPPROTO_TCP, 0, NULL, NULL, NULL};

        if ((rc = getaddrinfo(hostname, NULL, &hints, &result)) == 0)
        {
            struct addrinfo* res = result;

            /* prefer ip4 addresses */
            while (res)
            {
                if (res->ai_family == AF_INET)
                {
                    result = res;
                    break;
                }
                res = res->ai_next;
            }

            if (result->ai_family == AF_INET)
            {
                address.sin_port = htons(port);
                address.sin_family = family = AF_INET;
                address.sin_addr = ((struct sockaddr_in*)(result->ai_addr))->sin_addr;
            }
            else
                rc = -1;

            freeaddrinfo(result);
        }

        if (rc == 0)
        {
            mysock = socket(family, type, 0);
            if (mysock != -1)
            {
                int opt = 1;

                //if (setsockopt(mysock, SOL_SOCKET, SO_NOSIGPIPE, (void*)&opt, sizeof(opt)) != 0)
                //  printf("Could not set SO_NOSIGPIPE for socket %d", mysock);
                
                rc = ::connect(mysock, (struct sockaddr*)&address, sizeof(address));
            }
        }

        return rc;
    }

    int read(char* buffer, int len, int timeout_ms)
    {
        struct timeval interval = {timeout_ms / 1000, (timeout_ms % 1000) * 1000};
        if (interval.tv_sec < 0 || (interval.tv_sec == 0 && interval.tv_usec <= 0))
        {
            interval.tv_sec = 0;
            interval.tv_usec = 100;
        }

        setsockopt(mysock, SOL_SOCKET, SO_RCVTIMEO, (char *)&interval, sizeof(struct timeval));

        //printf("reading %d bytes\n", len);
        int rc = ::recv(mysock, buffer, (size_t)len, 0);
        if (rc == -1)
            Socket_error("read");
        //printf("read %d bytes\n", rc);
        return rc;
    }
    
    int write(char* buffer, int len, int timeout)
    {
        struct timeval tv;

        tv.tv_sec = 0;  /* 30 Secs Timeout */
        tv.tv_usec = timeout * 1000;  // Not init'ing this can cause strange errors

        setsockopt(mysock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,sizeof(struct timeval));
        int rc = ::write(mysock, buffer, len);
        //printf("write rc %d\n", rc);
        return rc;
    }

    int disconnect()
    {
        return ::close(mysock);
    }
    
private:

    int mysock; 
    
};

#endif