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Winsock problem

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  • M masnu

    Please elaborate as to which part of the post wasn't in "international" English and I will be happy to clarify.

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    Iain Clarke Warrior Programmer
    wrote on last edited by
    #11

    masnu wrote:

    Please elaborate as to which part of the post wasn't in "international" English and I will be happy to clarify.

    "r" "u" Mind you, once translated from text messaging, it was a helpful question / answer. Iain,

    I am one of "those foreigners coming over here and stealing our jobs". Yay me!

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    • M masnu

      Hi, I'm trying to enable my ARM development board to communicate with a PC. I can establish a connection and send data from the PC to the micro without any issues. When I try to send data from the micro to the PC, however, my socket doesn't respond to the data. A network analyzer shows that the packet was sent and formated properly. I have tried both TCP and UDP with the same results. Has anyone come across this before? Thanks.

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      M Offline
      masnu
      wrote on last edited by
      #12

      For those of you who are interested I finally figured out what the problem was. When I implemented the TCP/IP stack on the micro I made a mistake in the routine that calculates the IP header checksum. With an invalid checksum Winsock just disregarded the message. Once the correct checksum was sent everything worked fine. Thanks to all of you for your help. I appreciate it. Paul

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      • M masnu

        For those of you who are interested I finally figured out what the problem was. When I implemented the TCP/IP stack on the micro I made a mistake in the routine that calculates the IP header checksum. With an invalid checksum Winsock just disregarded the message. Once the correct checksum was sent everything worked fine. Thanks to all of you for your help. I appreciate it. Paul

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        Moak
        wrote on last edited by
        #13

        So it was not a Winsock problem at all. ;)

        Chat in Europe :java: Now with 24% more Twitter

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        • M Moak

          So it was not a Winsock problem at all. ;)

          Chat in Europe :java: Now with 24% more Twitter

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          masnu
          wrote on last edited by
          #14

          Nope! It was a me problem!! :-) Thanks Moak!

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          • M masnu

            For those of you who are interested I finally figured out what the problem was. When I implemented the TCP/IP stack on the micro I made a mistake in the routine that calculates the IP header checksum. With an invalid checksum Winsock just disregarded the message. Once the correct checksum was sent everything worked fine. Thanks to all of you for your help. I appreciate it. Paul

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            jeron1
            wrote on last edited by
            #15

            If you don't mind me asking, which network analyser did you use that didn't display an incorrect checksum?

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            • J jeron1

              If you don't mind me asking, which network analyser did you use that didn't display an incorrect checksum?

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              masnu
              wrote on last edited by
              #16

              I was using Wireshark, but it DID display an incorrect checksum. I just got busy doing other things and completely overlooked it. It wasn't until I focused on the problem that I paid attention to what the analyzer was telling me.

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              • M masnu

                I was using Wireshark, but it DID display an incorrect checksum. I just got busy doing other things and completely overlooked it. It wasn't until I focused on the problem that I paid attention to what the analyzer was telling me.

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                jeron1
                wrote on last edited by
                #17

                Cool, the reason I asked is we have a similar project coming up, and a long time ago I ran into a goofy problem with a fairly early version of Ethereal where it didn't flag some field as having an invalid value, I lost a lot of hair over that one! :)

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                • J jeron1

                  Cool, the reason I asked is we have a similar project coming up, and a long time ago I ran into a goofy problem with a fairly early version of Ethereal where it didn't flag some field as having an invalid value, I lost a lot of hair over that one! :)

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                  masnu
                  wrote on last edited by
                  #18

                  I can see how that would happen. Thankfully this one didn't take me that much time. Try WireShark http://www.wireshark.org/[^] it's a useful tool.

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                  • M masnu

                    I can see how that would happen. Thankfully this one didn't take me that much time. Try WireShark http://www.wireshark.org/[^] it's a useful tool.

                    M Offline
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                    Moak
                    wrote on last edited by
                    #19

                    What wonders me now... that you actually have seen the corrupt IP packages in Wireshark. I was assuming you ran Wireshark on Windows PC and your hosts are connected via a switch, shouldn't the switch throw away the IP packages from the embedded board with wrong header checksum instead of forwarding them?

                    Chat in Europe :java: Now with 24% more Twitter

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                    • M Moak

                      What wonders me now... that you actually have seen the corrupt IP packages in Wireshark. I was assuming you ran Wireshark on Windows PC and your hosts are connected via a switch, shouldn't the switch throw away the IP packages from the embedded board with wrong header checksum instead of forwarding them?

                      Chat in Europe :java: Now with 24% more Twitter

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                      Moak
                      wrote on last edited by
                      #20

                      Oops I was thinking wrong. IP packages are OSI Layer 3 and network switches operate on Layer 2... so they couldn't care less about IP header checksums. Sorry for the confusion. Happy coding! :)

                      Chat in Europe :java: Now with 24% more Twitter

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                      • M Moak

                        What wonders me now... that you actually have seen the corrupt IP packages in Wireshark. I was assuming you ran Wireshark on Windows PC and your hosts are connected via a switch, shouldn't the switch throw away the IP packages from the embedded board with wrong header checksum instead of forwarding them?

                        Chat in Europe :java: Now with 24% more Twitter

                        M Offline
                        M Offline
                        masnu
                        wrote on last edited by
                        #21

                        No.. I had my embedded board connected to the PC with a cross-over cable.. no switch.

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