Re: [dtn-users] A problem with dtntunnel

["[e-mail]" <[e-mail]>]

David,

I added this code and a log_debug inside the if-clause. According to the
log, this condition doesn't get true.
A have attached my logs and tcpdumps. Please, see dtntunnel_T.log - it's a
receiving dtntunnel log.
There are 4 bundles after a eof bundle. This doesn't happen with the
original dtntunnel.

-- 
Best regards,
Sergey Sireskin


2012/12/17 Zoller, David A. (MSFC-EO60)[HOSC SERVICES CONTRACT] <
[e-mail]>

> Hi Sergey,****
>
> I don’t have your setup and this has not been tested but give this a try.
> In TCPTunnel::Connection::handle_bundle in the while(1) loop add the test
> to see if the next_seqno_ is a match:****
>
> ** **
>
>     while (1) {****
>
>         iter = reorder_table_.find(next_seqno_);****
>
>         if (iter == reorder_table_.end()) {****
>
>             break;****
>
>         }****
>
> ** **
>
>         // add this code:****
>
>         // if seqno does not match then still a bundle missing****
>
>         if (iter->first != next_seqno_) {****
>
>             break;****
>
>         }****
>
> ** **
>
>         bundle = iter->second;****
>
>         log_debug("delivering %zu byte bundle with seqno %d (from reorder
> table)",****
>
>                   bundle->payload_.len(), next_seqno_);****
>
>     ****
>
>         reorder_table_.erase(iter);****
>
>         next_seqno_++;****
>
>     ****
>
>         queue_.push_back(bundle);****
>
>     }   ****
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> David Zoller****
>
> COLSA Corporation****
>
> HOSC / C107  ****
>
> (Office: [phone]
> *EMail: [e-mail]****
>
> ** **
>
> *From:* [e-mail] [mailto:[e-mail]] *On
> Behalf Of *[e-mail]
> *Sent:* Monday, December 17, 2012 6:40 AM
> *To:* David Zoller
>
> *Cc:* [e-mail]
> *Subject:* Re: [dtn-users] A problem with dtntunnel****
>
> ** **
>
> Hi David,
>
>
> Thanks for your patch, it works! :) Connection is cleanly terminated now.
>
> However, there still seems to be a problem. I run dtntunnel over a link
> with high latency and about 30% packet loss. The receiving nc sometimes
> gets FIN packet before it receives all the data. If I understand it right,
> on a lossy link bundles may come out of order. In this case the EOF bundle
> may come too early. I think that the reordering procedure in dtntunnel
> should be reviewed. Just for information, pure TCP performs better that DTN
> over this link.****
>
> 2012/12/14 David Zoller <[e-mail]>****
>
> Hi Sergey,****
>
> I can't stay away from a problem that is nagging at me so I made some time
> this morning. Going back to the original TCPTunnel.cc code, when a bundle
> is received that has the EOF indication, an empty bundle with the same EOF
> flag set needs to be returned to close the loop (the second FIN). There may
> still be some loose ends or clean up needed but try the code below at the
> end of the while loop.****
>
> ** **
>
> I did not do a packet capture but I saw that if the receiving nc is not
> running when you start the sender nc then the receiving dtntunnel logs an
> error on the failed connect and returns an EOF bundle which closes the
> sender nc. The EOF bundle could possibly be enhanced to include an error
> message.****
>
> ** **
>
> I agree that some applications could benefit from a "pretend to be a
> receiver" option with the default working as a bidirectional end-to-end TCP
> connection.****
>
> ** **
>
> Thanks for dragging me along kicking and screaming on this lesson in DTN
> and TCP tunneling. I've only been using dtntunnel as a one way UDP
> transmitter. I see a good fit for the TCP tunnel in an upcoming project and
> I'll try to make the pitch to use it. This is a pretty cool little app.***
> *
>
> Best regards,****
>
> DZ****
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> 484             delete b_recv;****
>
> 485 ****
>
> 486             if (recv_hdr->eof_) {****
>
> 487                 log_info("bundle had eof bit set... closing
> connection");****
>
> 488 ****
>
> 489                 if ( !sock_eof ) {****
>
> 490                     sock_eof = true;****
>
> 491                     // send an empty bundle back since we did not
> initiate the close****
>
> 492                     dtn::APIBundle* b = new dtn::APIBundle();****
>
> 493                     hdr.eof_ = 1;****
>
> 494                     hdr.seqno_ = ntohl(send_seqno++);****
>
> 495                     memcpy(b->payload_.buf(sizeof(hdr)), &hdr,
> sizeof(hdr));****
>
> 496                     b->payload_.set_len(sizeof(hdr));****
>
> 497                     int err;****
>
> 498                     if ((err = tunnel->send_bundle(b, &dest_eid_)) !=
> DTN_SUCCESS) {****
>
> 499                         log_err("error sending final socket closed
> packet bundle: %s",****
>
> 500                                 dtn_strerror(err));****
>
> 501                         tcptun_->kill_connection(this);****
>
> 502                         exit(1);****
>
> 503                     }****
>
> 504                     delete b;****
>
> 505                 }****
>
> 506                 sock_.close();****
>
> 507                 goto done;****
>
> 508             }****
>
> 509         }****
>
> 510     }****
>
> 511 ****
>
> 512  done:****
>
> ** **
>
>
>
>
> --
> Best regards,
> Sergey Sireskin
>
> ****
>