accessing IPV6 extension header for fragmented packet

[PrabhurRajashekaraiah]

Hi,

I am trying to implement a code where I am trying to access the extension headers of IPv6 if (IPV6_FRAG_HDR == ipv6.next_header().

I am accessing extension headers IPv6::headers_type extHeadr = ipv6.headers(); I need to access all the fields in the fragmentation header i.e., Next Header field, Fragment Offset field, More Fragments flag, and Identification field. I am not getting any example on the internet for the same. can someone help me with a sample program to access IPv6 extension header for fragmented packet.

Many Thanks,
Prabhu

[mfontanini]

There's currently no helper function to parse the IPv6 fragmentation header, I might add one though. Also, looking up headers in IPv6 was pretty broken and only recently I fixed it, the fix being on the develop branch.

You can parse the contents of the option yourself anyway, you can create a packed struct and extract them (see how e.g. the IPv6 header is defined in ipv6.h).

[PrabhurRajashekaraiah]

Hi,
Thanks for the reply.
The header file you are referring to doesnt have extension header contents. I would appreciate, If you could provide any further help on this.

[mfontanini]

I didn't say that linked file had the extension header contents, that's an example of how to write a bitfield struct to extract the fields you need. You can read the RFC where the fragment header is defined and parse accordingly.

[gerald-dotcom]

@mfontanini Since you added parsing support for extensions on #287 , is there are any examples how one can access the fields?

I tried my best but couldn't find a way.

[laudrup]

Isn't the search_header() function what you're looking for?

You can have a look at ipv6_test.cpp.