nanomsg REP/REQ example with threads client code

#define AUTH_SOCKET_ADDRESS "ipc://oauth2"
#define AUTH_SUCCESS        0
#define AUTH_FAILED         1
#define AUTH_SOCK_FAILED    2
#define AUTH_BIND_DAILED    3
#define AUTH_SOME_OTHER     4

struct core_buf {
    u_int8_t        *data;
    u_int64_t       length;
    u_int64_t       offset;
};

struct http_request {
    u_int8_t            method;
    u_int8_t            flags;
    int             status;
    u_int64_t           start;
    u_int64_t           end;
    u_int64_t           total;
    char                *query_string;
};

/*  This is part of webserver code..see only nanomsg use case..for clarity I have provided
    the  (part of)struct http_request definition too. */

/*  A web client send a request to my webserver, req holds the web client request.
    This method is trying to send the request query string to REP end-point...and the response
    from the REP end-point will send to web client  as the response to the web client request. */
int send_authentication_request(struct http_request* req)
{
    int sock = nn_socket (AF_SP, NN_REQ);

    if(sock >= 0)
    {
        core_debug("send_authentication_request: sock created");
        if(nn_connect (sock, AUTH_SOCKET_ADDRESS) >= 0)
        {
            char *resp = NULL;
            int bytes = 0;
            int result;
            core_debug("'%s' connected with %s",AUTH_SOCKET_ADDRESS, req->query_string);

            result = nn_send (sock, req->query_string , strlen(req->query_string), 0);

            core_debug("nn_send result: %d",result);    /* *****    This is successful */

    //  Here its waiting for REP end-point reply, which its not getting...
            bytes = nn_recv (sock, &resp, NN_MSG, 0);   /* *****    Waiting for response */

            core_debug("bytes received: %d",bytes);

            if(bytes > 0)
            {
                //  send received data to the web client here...

                nn_freemsg (resp);
            }
        }
        else
            return AUTH_BIND_FAILED;
    }
    else
        return AUTH_SOCK_FAILED;

    return AUTH_SUCCESS;
}