using functional pointers( C style ) with pybind

Question

How to use functional pointers(C style) with pybind to implement callback functionality.The c++ code has to call the python function . I am encountering errors related to type conversion when trying to use C-style function pointers with Pybind11 for callback functionality.

//cplusplus.cc
typedef char* callback_type)(const char* name, const Server* server)
class Server{
callback_type server_callback;
}

char *cplusplus_readfile(const char* name,Server* server) {
    char *buffer = server->server_callback(name,server);
    return buffer; // Added return statement
}

//server_test.py
import server_wrapper as s
BUFFER_LENGTH = 1024 
class Test:
    def server_read(self,name,server):
        print("Python function called with name:", name)
        buffer = b''
    // do something
        return buffer
  def test_func():
      server= s.Server()
      server.register_server_callback(self.cplusplus_readfile)

// server_wrapper .cc
#include <pybind11/pybind11.h>
#include <pybind11/embed.h>
#include <pybind11/stl.h>
#include <pybind11/functional.h>
#include <cstring> // Added for strcpy
#include "Server.h" 
namespace py = pybind11;

PYBIND11_MODULE(server_wrapper, m) {

    py::class_<Server>(m, "server")
        .def(py::init<>())
        .def_readwrite("server_callback", &Server::server_callback);
    .def("register_server_callback", [](py::object &obj,py::function py_callback){
            callback_type cb=[py_callback](const char * name , const Server* server) -> char*{
            py::object result = py_callback(name,server);
            std::string str_result = py::str(result);
            char * buffer = new char[str_result.length()+1];
            std::strcpy(buffer,str_result.c_str());
            return buffer;

        };
        Server &s = obj.cast<Server>();
        s.server_callback=cb;
    }, "function to set callback");

}

I am getting the following errors :

..../include/pybind11/detail/../detail/type_caster_base.h:1021:50: error: invalid conversion from 'char* (*)(const char*, const char*)' to 'const void*' [-fpermissive]
 1021 |         return type_caster_generic::src_and_type(src, cast_type, instance_type);
      |                                                  ^~~
      |                                                  |
      |                                                  char* (*)(const char*, const char*)
../include/pybind11/detail/../detail/type_caster_base.h:851:30: note:   initializing argument 1 of 'static std::pair<const void*, const pybind11::detail::type_info*> pybind11::detail::type_caster_generic::src_and_type(const void*, const std::type_info&, const std::type_info*)'
  851 |     src_and_type(const void *src,
    

using functional pointers( C style ) with pybind