[dtrace-discuss] Re: [networking-discuss] DTrace Network Providers, take 2

[Darren.Reed at Sun.COM]

Brendan,

I had a quick look through the URL you provided and one thing
struck me as very odd - none of the protocol headers (IP, TCP,
UDP) expose the checksum value.  Can you explain your rationale
for this?  Whlie this is perhaps uninteresting on the inbound side,
it is quite interesting on the outbound side.

Also, can you explain where the probes for each protocol fit in
relation to the greater processing for the protocol?

For example, with TCP you mention that it is possible to see if
invalid flag combinations have been supplied - does this mean
the TCP header has also not been checksum'd?

Will tracemem() be told how to walk the packet, so I can the below?
tracemem(args[1]->ip_hdr, args[1]->ip_plength)

...well, that'd also require ip_hdr being added to ipinfo_t.

Adding ipv4_hl (or whatever you want to call it) would also be
beneficial for people who want to use dtrace to look for packets
with IP options in them.

For IPv6, how do you see this design evolving to include looking
at extension header data?

Darren