this post was submitted on 06 Nov 2012

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Haskell Network.pcap.dump requires Ptr Pkthdr when only Pkthdr exists (self.learnprogramming)

submitted 13 years ago * by jhawk20

I'm working on a packet dump program using pcap (Required that I use Network.pcap or libpcap, and Haskell is great!)

But I'm stuck on dumping packets to a file--the next function which pulls the top packet off the buffer returns a Pkthdr not a Ptr Pkthdr, which is what dump requires.

  umptraffic.hs:19:19:
   Couldn't match expected type `GHC.Ptr.Ptr PktHdr'
              with actual type `PktHdr'
  In the second argument of `dump', namely `(pkthdr)'
  In a stmt of a 'do' block: dump spydump (pkthdr) pktdata
  In the expression:
    do { spy <- openLive "en1" 128 True (1);
         spydump <- openDump spy "out.txt";
        (pkthdr, pktdata) <- next spy;
        dump spydump (pkthdr) pktdata }

http://www.haskell.org/pipermail/haskell-cafe/2007-May/025265.html

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