We cannot pass the context of the program to mqtt publish_callback

[Lecrapouille]

Why not passing the context of the program in mqtt_init ? Because in void publish_callback(void** /*unused*/, struct mqtt_response_publish *published) you have to store data in a global variable since there is no way to access it.

Idea:

struct mqtt_client client;
struct context { int foo; int bar; } my_context;

client->context = &my_context;
...

static void publish_callback(void** /*unused*/, struct mqtt_response_publish *published)
{
   struct context* my_context = (struct  context*) published->context;
   my_context->foo = process(published->application_message, published->application_message_size);
}

[arielmol]

just found the same

[Lecrapouille]

@arielmol I have made a quick implementation in C++ if you wish https://github.com/Lecrapouille/MQTT