int receive_init(int *seq, msg *last_msg) {
    // return -1 if error

    msg *r = receive_message_timeout(3*TIME*1000);
    if (r == NULL)
        return -1;

    kermit k = msg_to_kermit(r);
    (*seq) = ((*seq) + 1) % 64; // seq++

    if (!verify(r, k.CHECK) || k.SEQ != (*seq) - 1) {
        // mesaj gresit

        // printf(" len din r: %d\n", r->len - 3);
        // printf(" len din k: %d\n", k.LEN + 2 - 3);
        // printf(" crc din r: %d\n", crc16_ccitt(r->payload, r->len - 3));
        // printf(" crc din k: %d\n", crc16_ccitt(r->payload, k.LEN - 1));

        // printf(" check in recv: %d\n", k.CHECK);
        // printf("in recv %d %d\n", r->payload[15], r->payload[16]);

        send_nak(seq, last_msg);

        // printf("NACK sent...\n");

        (*seq) = ((*seq) + 1) % 64; // seq++
        return receive_init(seq, last_msg);
    }

    // compute msg

    // DATA field
    char *data = (char *) calloc(SEND_INIT_DATA_SIZE, 1);

    data[0] = MAXL;
    data[1] = TIME;
    data[2] = NPAD;
    data[3] = PADC;
    data[4] = EOL;

    (*last_msg) = make_kermit(SEND_INIT_DATA_SIZE, seq, 'Y', data);
    (*seq) = ((*seq) + 1) % 64;
    send(last_msg);

    // printf("Send-Init received! (receiver)\n");
    // printf("aci??\n");
    return 0;
}