Ethereal log show checksum error

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Bill
2007-03-23
2013-05-30
  • Bill

    Bill - 2007-03-23

    When I look at the TCP traffic being generated by MediaTomb, I am noticing that all non 0 length messages are displayed as having an incorrect TCP Checksum.  The Header Checksum is correct.

    Can someone point me in the correct direction as to where the TCP checksum is calculated?

    I'm running FC4 on an x86_64 machine.

    I can post the packet contents if that would help diagnose the problem.

    Thanks,
      Bill

     
    • Jin

      Jin - 2007-03-23

      Uhm, the libupnp code uses default socket operations, nothing is being done on a level where messing up TCP checksums would be possible.

      Is this somehow causing any undesired behaviour or any noticable problems?

      We could of course look into that.

      Greetings,
      Jin

       
    • Bill

      Bill - 2007-03-23

      Jin,
      Thanks for the quick response and info.

      I am having problems getting my DSM-320 to play a Shoutcast stream.  I have seen the other thread involving the DSM-320 and shoutcast, so I know that it is possible, and that I have my system configured as you suggested.  (As well as having tried many other variations :-).   With my setup the DSM-320 gives a very quick "Unable to load file".  And from the ethereal logs it never even attempts to connect to the shoutcast server port.

      It will play normal mp3's from the filesystem.

      I have version 1.09 of firmware in the DSM-320.  MediaTomb-0.9.0-pre

      As far as libupnp, I used yum to install and have version 1.4.1-1.fc4 of both libupnp and libupnp-devel.

      I have been trying to compare ethereal captures among MediaTomb, Tversity and Twonky to see if I can see and understand what the difference might be (since it will play from the other 2).  I really like the simplicity and feel of MediaTomb the best of the three, so I would really like to figure this out.  I'm slowly starting to be able to read the upnp data format.  Do you have a suggestion on a primer to read for what all the fields are intended for. 

      Cheers,
        Bill

       
    • Bill

      Bill - 2007-03-23

      In looking more at the code etc, I think I miss understood something.  Is the libupnp that you are using under the tombupnp subdirectory?  If so, ignore what version I have installed elsewhere on my system.

      I started parsing out the xml that is sent by the servers and there doesn't seem to be anything that jumps out.
      TV
        <item parentID="0/1/6/5416" restricted="true" id="0/1/6/5416/106067">
          <upnp:class>object.item.audioItem.audioBroadcast</upnp:class>
          <dc:title>Bill Shoutcast</dc:title>
          <res protocolInfo="http-get:*:audio/mpeg:*">http://192.168.4.194:9002/</res>
        </item>
      DM
        <item id="2" parentID="0" restricted="0">
          <dc:title>Bill Shoutcast</dc:title>
          <upnp:class>object.item.audioItem.audioBroadcast</upnp:class>
          <res protocolInfo="http-get:*:audio/mpeg:*">http://192.168.4.194:9002/</res>
        </item>

      {I did formatting, and conversions from &quot; &lt; &gt; etc, so I may have missed a small detail}
      So the big differences I noticed (aside from the TCP CHECKSUM INCORRECT)
      1) TV sent the item as the only item in the packet, DM sent it as the 3rd after 2 containers.
      2) restricted="true" -vs- restricted="0"
      3) DM has <LF> followed by 1 or more spaces following most </> tags where TV has nothing

      Am I headed in the right direction?

      Cheers,
        Bill

       
    • Nik

      Nik - 2007-03-24

      Bugger, I've just spent all night getting my euro dsm upgraded to 1.9fw, after trying the most recent build along with the 1.9fw which should be the same setup as Jin now, and I'm still getting the file not found popping up instantly, I wish I saw this post earlier :D

       
    • Bill

      Bill - 2007-03-24

      Jin
      I just ran ethereal on another machine, and it looks like the checksum's are correct when they hit the wire.  Hope you haven't spent too much time on it.

      Nik
      Were you able to get the shoutcast to work at all, or is it just Jin who has the luck with making it work?

      Either way we should probably hop threads to the one you (Nik) started. Since I believe this topic (bad checksums) is actually a mistake on my part.

      Thanks,
        Bill

       
    • Jin

      Jin - 2007-03-24

      Hi,

      uhm... weird stuff, about shoutcast :) I am in contact with Nik, and he can not reproduce my success either.

      Regarding UPnP - yes, tombupnp is based on libupnp and is patched by us.
      You can find all specs regarding UPnP on http.//www.upnp.org/

      What you pasted were fragments of the DIDL-Lite XML, looks usual to me, nothing really special about it; you can set the upnp:class to object.item.audioItem.audioBroadcast for the external URL items in our web UI as well.

      And hell.. it worked for me!

      Is it possible, that the manufacturer tag is playing some role? I've been testing subtitles, and they can only be enabled if add a special option to the device description XML. This can be done by putting:
      <manufacturerURL>redsonic.com</manufacturerURL> in the config.xml file.

      Drop by in IRC for some realtime debugging, Nik is around there too, maybe we can figure this out together.

      Greetings,
      Jin

       

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