How read information from node in C?

[lykamspam]

Platform

ESP32

Description

I need information about nodes.
Similar python "meshtastic --nodes"

How I can to do this? Here is my code. What is wrong? I'm not get any data. I use Heltec 3

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <errno.h>

#define SERIAL_PORT "/dev/ttyUSB0" 
#define BAUDRATE B115200  

// Funkcja do wysyłania i odbierania danych
void send_and_receive(int serial_port, const char *command) {
    printf("Wysyłana komenda: %s\n", command); // Debugowanie
    write(serial_port, command, strlen(command));

    // Czekaj na odpowiedź
    usleep(2000000);  
    char response[256];
    int num_bytes = read(serial_port, response, sizeof(response) - 1);
    if (num_bytes > 0) {
        response[num_bytes] = '\0'; // Zakończenie łańcucha
        printf("Otrzymano odpowiedź: %s\n", response); // Przekazanie odpowiedzi
    } else if (num_bytes < 0) {
        perror("Błąd podczas odbierania danych");
    } else {
        printf("Brak odpowiedzi.\n");
    }
}

int main() {
    int serial_port;
    struct termios options;

    // Otwieranie portu szeregowego
    serial_port = open(SERIAL_PORT, O_RDWR | O_NOCTTY | O_NDELAY);
    if (serial_port < 0) {
        perror("Nie można otworzyć portu szeregowego");
        return -1;
    }

    // Ustawienia portu szeregowego
    tcgetattr(serial_port, &options);
    cfsetispeed(&options, BAUDRATE);
    cfsetospeed(&options, BAUDRATE);
    options.c_cflag |= (CLOCAL | CREAD); // Ustawienia lokalne i odczyt
    options.c_cflag &= ~PARENB; // Brak parzystości
    options.c_cflag &= ~CSTOPB; // 1 bit zatrzymania
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8; // 8 bitów danych
    options.c_iflag &= ~(IXON | IXOFF | IXANY); // Wyłączenie kontroli przepływu
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); // Wyłączenie trybu kanonicznego i echo
    options.c_cc[VMIN] = 0;  // Minimalna liczba znaków do odbioru
    options.c_cc[VTIME] = 10; // Czas oczekiwania w dziesiątych częściach sekundy
    tcsetattr(serial_port, TCSANOW, &options);

    // Wysyłanie polecenia do uzyskania węzłów
    const char *command = "{\"cmd\": \"get\", \"args\": {\"type\": \"nodes\"}}\n";
    send_and_receive(serial_port, command);

    // Zamknięcie portu szeregowego
    close(serial_port);
return 0;
}

[esev]

Hi @lykamspam

This guide has more information about how to use the serial interface: https://meshtastic.org/docs/development/device/client-api/

[GUVWAF]

The Arduino client might also be of help: https://github.com/meshtastic/Meshtastic-arduino

[i0vt]

Both links do not contain any code example. I too would like to write a Linux terminal client. Maybe just correct the example at the top. Throwing links that don't give anything is pointless.

[GUVWAF]

The Arduino client is an example of how to implement an interface in C++: https://github.com/meshtastic/Meshtastic-arduino/blob/master/src/mt_protocol.cpp

Yes, it’s not C, but I don’t know of any C implementation.
The device doesn't understand --nodes commands. From this, the Python CLI creates protobuf messages, and you'll have to do the same in C.

[lykamspam]

I don't really understand. I don't think there is any client in C. This is sad news.

Such a program would be convenient for writing a library for Ruby, Haskell or some GUI program.

Would the program I showed be suitable for that in terms of sending and reading? Do you know of a way to debug what the python program is sending? Could you ask someone from the developers to write a sample program or improve my program?

[GUVWAF]

Would the program I showed be suitable for that in terms of sending and reading?

No, you need to interact with the device via the protobuf messages, so you'll e.g. need the nanopb library. E.g. for NodeInfo you have to send a ToRadio message with a want_config_id set.

Unfortunately there's no small sample program I know of in C, and the closest thing I know of is the Arduino client I linked above.