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List:       nmap-dev
Subject:    Re: [PATCH] TCP Idle Scan in IPv6
From:       David Fifield <david () bamsoftware ! com>
Date:       2013-06-30 2:21:02
Message-ID: 20130630022102.GC15395 () ignominy ! bamsoftware ! com
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On Sat, Jun 29, 2013 at 02:47:00PM -0700, David Fifield wrote:
> > +  //for me, htonl is not necessary, instead diving by 2
> >    if (seqclass == IPID_SEQ_BROKEN_INCR) {
> >      /* Convert to network byte order */
> > -    startid = htons(startid);
> > -    endid = htons(endid);
> > -    return endid - startid;
> > +    //startid = htonl(startid);
> > +    //endid = htonl(endid);
> > +    return (endid - startid)/2;
> >    }
> 
> You seem to be treating IPID_SEQ_BROKEN_INCR as meaning "counts by 2,"
> but it really means "counts by 1 but byteswapped." That is, instead of
> counting
> 	0000,0001,0002,...,00ff,0100,0101,0102,...,feff,ff00,ff01,...
> it counts
> 	0000,0100,0200,...,ff00,0001,0101,0201,...,fffe,00ff,01ff,...
> You probably need to add a new IPID_SEQ define for "counts by 2."
> 
> That said, calling htons to swap bytes will not work on big-endian
> platforms, which is a bug in the current code.

I committed a fix for this in r31162.

David Fifield
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