[Bro] new_packet, BuildHeader and IPv6

[Julien Desfossez]

Hello,

I am working on the function NetSessions::BuildHeader and I have two
questions :
- This function is called in NetSessions::DoNextPacket just after a "if
( new_packet )" but this condition seems to be always false.
Is there something to activate to make it work ?

- As NetSessions::BuildHeader takes in parameter "const struct ip* ip" I
have two solutions to make it work with IPv6 : copy this function and
adapt it for IPv6 or change the prototype to :
"NetSessions::BuildHeader(const IP_Hdr* hdr)".
I have currently chosen the second option, but I'd like to hear what you
think about that before I make too much changes.

Thank you,

Julien Desfossez