tftp get and last ack hanlding

[Yegor Yefremov]

I'm using dnsmaq as tftp server. When I execute tftp file on barebox
2016.07.0 I get the required file, but dnsmasq complains about missing
ACK (my interpretation of dnsmaq source code). If I'm performing the
same operation in Linux using busybox ftfp - everything is OK, i.e.
instead of "failed sending" I get "sent". Is this a desired barebox
tftp behavior?

dnsmasq log:

Jan 23 08:30:25 buildroot daemon.err dnsmasq-tftp[225]: error 0
received from 192.168.0.79
Jan 23 08:30:25 buildroot daemon.info dnsmasq-tftp[225]: failed
sending /data/tftp/vmlinuz.bin to 192.168.0.79

Relevant dnsmaq code in [1], see how endcon is set:

      if (difftime(now, transfer->timeout) >= 0.0)
        {
          int endcon = 0;

          /* timeout, retransmit */
          transfer->timeout += 1 + (1<<transfer->backoff);

          /* we overwrote the buffer... */
          daemon->srv_save = NULL;

          if ((len = get_block(daemon->packet, transfer)) == -1)
            {
              len = tftp_err_oops(daemon->packet, transfer->file->filename);
              endcon = 1;
            }
          /* don't complain about timeout when we're awaiting the last
             ACK, some clients never send it */
          else if (++transfer->backoff > 7 && len != 0)
            {
              endcon = 1;
              len = 0;
            }

          if (len != 0)
            while(sendto(transfer->sockfd, daemon->packet, len, 0,
                         (struct sockaddr *)&transfer->peer,
sa_len(&transfer->peer)) == -1 && errno == EINTR);

          if (endcon || len == 0)
            {
              strcpy(daemon->namebuff, transfer->file->filename);
              sanitise(daemon->namebuff);
              my_syslog(MS_TFTP | LOG_INFO, endcon ? _("failed sending
%s to %s") : _("sent %s to %s"), daemon->namebuff, daemon->addrbuff);
              /* unlink */
              *up = tmp;
              if (endcon)
                free_transfer(transfer);
              else
                {
                  /* put on queue to be sent to script and deleted */
                  transfer->next = daemon->tftp_done_trans;
                  daemon->tftp_done_trans = transfer;
                }
              continue;
            }
        }

[1] http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=blob;f=src/tftp.c;h=618c4062e07234336e09a6689a265763a4d7981c;hb=HEAD#l570

Yegor