int send_request(int socket, request_s *request) {
    char *buffer;

    if ((buffer = (char *) malloc(MSG_SIZE)) == NULL) {
        ERR("malloc");
        return -1;
    }

    request_to_string(request, buffer);

    if (TEMP_FAILURE_RETRY(send(socket, buffer, MSG_SIZE, 0)) < 0) {
        free(buffer);
        ERR("send");
    }

    free(buffer);
    return 0;
}

/***
 * Communicates with server. First sends the request, then gets the response.
 * Returns:
 *             0    success
 *             -1    provided request is NULL
 *             -2    sending request failed
 *             -3    receiving response failed
 */
int communicate(int socket, request_s *request, response_s *response) {
    fd_set rfds;
    sigset_t mask, old_mask;
    char buffer[MSG_SIZE];

    if (request == NULL)
        return -1;
    else {
        if (send_request(socket, request) < 0) {
            printf("Sending request failed.\n");
            return -2;
        }
    }

    FD_ZERO(&rfds);
    FD_SET(socket, &rfds);
    sigemptyset(&mask);
    sigaddset(&mask, SIGINT);
    sigprocmask(SIG_BLOCK, &mask, &old_mask);

    if (pselect(socket + 1, &rfds, NULL, NULL, NULL, &old_mask) > 0) {
        if (FD_ISSET(socket, &rfds)) {
            if (TEMP_FAILURE_RETRY(recv(socket, (void *) buffer, MSG_SIZE, 0))
                    < 0)
                return -3;
            string_to_response(buffer, response);
            return 0;
        }
    }
    if (errno == EINTR) {
        request->type = MSG_EXIT_REQ;
        send_request(socket, request);
        TEMP_FAILURE_RETRY(close(socket));
        exit(EXIT_FAILURE);
    }
    return -4;
}