FastCGI with C ++ and NGINX

I'm trying to make a small server to study using fastCGI with C ++ without using any library. My problem is that via socket NGINX even connects but does not give me any information about the request, and if I write some callback it generates error 502.

NOTE: I am using a class Socket I created. link

Here's my C ++ code.

#include "Socket.h"
#include "thread"


using namespace Tigre;


int main(int argc, char *argv[], char** envp)  {
    try {
        Socket *s = new Socket("localhost", 9000, TCP);
        s->Bind(5);
        std::cout << "Esperando Cliente\n";
        Socket *cliente = s->Accept();
        //cliente->Write("\r\n");
        //cliente->Write("Bem vindo ao servidor!");
        std::cout << "Esperando Mensagem do Cliente\n";

        int i = 0;
        while(i < 100) {
            std::cout << "'"<< cliente->Read() << "'" << "\n";
            i++;
        }
    }catch (SocketException &e){
        std:cerr << e.what();
    }
}

NGINX Configuration:

worker_processes  1;

events {
    worker_connections  1024;
}

http {
include       mime.types;
default_type  application/octet-stream;

sendfile        on;

keepalive_timeout  65;


server {
    listen       80;
    server_name  localhost;

    location / {
            root           share/nginx/html;

            fastcgi_param REQUEST_METHOD $request_method;
            fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
           fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
            fastcgi_param  SERVER_SOFTWARE    nginx;
            fastcgi_param  QUERY_STRING       $query_string;
            fastcgi_param  REQUEST_METHOD     $request_method;
            fastcgi_param  CONTENT_TYPE       $content_type;
            fastcgi_param  CONTENT_LENGTH     $content_length;
            fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
            fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
            fastcgi_param  REQUEST_URI        $request_uri;
            fastcgi_param  DOCUMENT_URI       $document_uri;
            fastcgi_param  DOCUMENT_ROOT      $document_root;
            fastcgi_param  SERVER_PROTOCOL    $server_protocol;
            fastcgi_param  REMOTE_ADDR        $remote_addr;
            fastcgi_param  REMOTE_PORT        $remote_port;
            fastcgi_param  SERVER_ADDR        $server_addr;
            fastcgi_param  SERVER_PORT        $server_port;
            fastcgi_param  SERVER_NAME        $server_name;
            fastcgi_pass  127.0.0.1:9000;
    }
}

}

EDIT1: I made a change in the std::cout << "'"<< cliente->Read() << "'" << "\n"; line to check if there was any blank value, and it actually arrives as you can see below. OBS2 The error only occurs when Nginx generates error 502 and returns to the browser.

Console:

Esperando Cliente
Esperando Mensagem do Cliente
''
'Sem conexão com o Socket.
Process finished with exit code 0