On Thu, Sep 6, 2018 at 8:40 PM, Roopa Prabhu <ro...@cumulusnetworks.com> wrote: > On Thu, Sep 6, 2018 at 2:10 AM, Patrick Ruddy > <pru...@vyatta.att-mail.com> wrote: >> Some userspace applications need to know about IGMP joins from the >> kernel for 2 reasons: >> 1. To allow the programming of multicast MAC filters in hardware >> 2. To form a multicast FORUS list for non link-local multicast >> groups to be sent to the kernel and from there to the interested >> party. >> (1) can be fulfilled but simply sending the hardware multicast MAC >> address to be programmed but (2) requires the L3 address to be sent >> since this cannot be constructed from the MAC address whereas the >> reverse translation is a standard library function. >> >> This commit provides addition and deletion of multicast addresses >> using the RTM_NEWMDB and RTM_DELMDB messages with AF_INET. It also >> provides the RTM_GETMDB extension to allow multicast join state to >> be read from the kernel. >> >> Signed-off-by: Patrick Ruddy <pru...@vyatta.att-mail.com> >> --- >> v3 rework to use RTM_***MDB messages as per review comments. > > Patrick, this version seems to be using RTM_***MDB msgs with the > RTM_*ADDR format. > We cant do that...because existing RTM_MDB users will be confused. > > My request was to evaluate RTM_***MDB msg format. see > nlmsg_populate_mdb_fill for details. > > If you can wait a day or two I can share some experimental code that > moves high level RTM_*MDB msg handling into net/core/rtnetlink.c > similar to RTM_*FDB >
I was trying to get a default per interface (non bridge) RTM_*MDB working, but realized that the dev->mc entries are already getting dumped as part of RTM_*FDB msgs instead of RTM_*MDB. (see net/core/rtnetlink.c:ndo_dflt_fdb_dump). This adds another wrench. so, that puts us back to your use of RTM_NEWADDR. Instead of using IFA_ADDRESS, you could introduce a new one IFA_IGMP_MULTICAST (since IFA_MULTICAST is already taken). To keep existing users of RTM_NEWADDR unaffected. I think you can use the IPMR family with RTM_NEWADDR. We can introduce new notification group. (We can choose to add a new family too, but that seems unnecessary) since you only need dumps: rtnl_register(RTNL_FAMILY_IPMR, RTM_GETADDR, NULL, igmp_rtm_dumpaddrs, 0); For notifications, since we already have many variants for routes, I don't see a problem adding similar addr variants RTNLGRP_IPV4_MCADDR (Others on the list may have more feedback).
