Refactor PIM Join/Prune send logic to allow more than ~75 multicast r…

[idismmxiv]

…eceivers.

Gather Joins/Prunes to buffer only up to the point where the PIM message is at the most 576 bytes on the wire, previous buffer size was 8192 which was way too large to fit anywhere else than massive jumbo-frame MTU links. The problem only occurred after there were ~75+ or more receivers behind one link with MTU of 1500.

• Change all J/P buffers to be dependent on MAX_JP_MESSAGE_SIZE rather than having separate limits for different buffers.
• Added logic that verifies that no larger than MAX_JP_MESSAGE_SIZE messages are crafted to be sent into the network.
• Prevent (,,RP) J/P from creating empty group entries when received. This was caused by logic that assumed that if curr_group != group then we must pack the group even though the group might not have any joins/prunes. (Not verified that this actually works as intended.)
• Prevent (,,RP) J/P from clearing the normal J/P group and mask info. (Not verified that this actually works as intended.)
• Removed "dead" logic that caused reaching of 254 groups in single J/P to trigger a premature send of J/P message that would little later lead to use-after-free. Moved the logic one function earlier and set the pointer. Steps: 2437:pack_jp_message(pim_nbr); 2677:send_jp_message(pim_nbr); 2733:return_jp_working_buff(pim_nbr); 2656:free(bjpm); 2460:bjmp->curr_group = group

[troglobit]

Interesting pull request, and very big!

I'm planning a v2.3.1 bugfix release soon (this weekend hopefully). I hope it's OK if we postpone this PR for the v2.4.0 release cycle?

[idismmxiv]

Hi, Yeah it's OK to postpone it.

[troglobit]

Thanks for the quick reply! :smiley:

[idismmxiv]

No problem. Oh btw, I put accidentally wrong line numbers to the commit message use-after-free steps so here are the correct ones:

• 2375:pack_jp_message(pim_nbr);
  • 2617:send_jp_message(pim_nbr);
  • 2667:return_jp_working_buff(pim_nbr);
    • 2556:free(bjpm);
• 2398:bjmp->curr_group = group

[troglobit]

You can just update the commit with git commit --amend and git push --force to your branch, then the PR will be updated.

While you're at it, see if you can shorten the first line <=70 chars and add a Signed-off-by: person personson <person.personson@email.tld> line for everyone that's contributed/audited the commit.