Re: Adding offset to 'Address

[Kim Rostgaard Christensen <krc@greenpc.dk>]

Bj�rn wrote:
> On 12 Sep, 10:35, Kim Rostgaard Christensen <k...@greenpc.dk> wrote:
>> Hi
>>
>> How does one go about setting a 'Address + (size of other record) to a
>> record at runtime ?
>>
>> In brief, I am switching over "Frametype" in a Ethernet frame record, to
>> dynamically assign the next record by type (IPv4,IPv6,ARP, etc.)
>> My "datablob" is a *u_char from a imported C function.
>>
>> So I have:
>>
>>   Raw_Bytes : access Unsigned_Char
>>   for Ethernet_Header'Address use Raw_Bytes.all'Address;
>>
>> and additionally need something like:
>>   for IP_Packet'Address use Raw_Bytes.all'Address + Ethernet_Header'Size;
>>
>> Also, I am not confident that this _the_ solution, so other approaches
>> are very welcome. For those curious about what it is all about, I ran a
>> gnathtml on the source and made it available athttp://krc.greenpc.dk/hovedopgave/html/index.htm
>>
>> Regards
>> Kim Rostgaard Christensen
> 
> I was also playing around with PCAP earlier this year. I have not yet
> finished what I intended to do but I got basic IP reassembly and TCP
> session reconstruction to work. I uploaded the files to
> http://www.mediafire.com/?1neezbx5bb1 if you want to have a peek.
> However, note that this is work in progress. The application is not
> finished and the quality of the code will need improvement. There are
> also a lot more special cases in TCP handling that will need to be
> handled.
> 
> Regards
> Bj�rn

Wow, this is a very good source of inspiration, thanks

- krc