potential buffer overflow for the message size

[joegasewicz]

From skeeto on Reddit:

Instead, get the string length, allocate enough for the whole thing, then memcpy it into place. And before any of that, check for null. Technically it's undefined to pass null for %s in the printf (FMQ_LOGGER), too.

$ eval cc -g3 -fsanitize=address,undefined *.c $(pkg-config --cflags --libs libulfius jansson)
$ ./a.out

Then in another terminal:

$ curl -d @examples/sample.json http://0:8005/provider
The server crashes:

Starting server on http://localhost:8005
Received: (null)
tcp.c:71:5: runtime error: null pointer passed as argument 2, which is declared to never be null
Context:

    data->message = malloc(sizeof(char) * 1024);
    strcpy(data->message, message);