> -----Original Message-----
> From: Markus Armbruster <arm...@redhat.com>
> Sent: Wednesday, June 16, 2021 9:26 PM
> To: Zhang, Chen <chen.zh...@intel.com>
> Cc: Lukas Straub <lukasstra...@web.de>; Daniel P.Berrangé
> <berra...@redhat.com>; Li Zhijian <lizhij...@cn.fujitsu.com>; Jason Wang
> <jasow...@redhat.com>; qemu-dev <qemu-devel@nongnu.org>; Dr. David
> Alan Gilbert <dgilb...@redhat.com>; Gerd Hoffmann <kra...@redhat.com>;
> Zhang Chen <zhangc...@gmail.com>; Eric Blake <ebl...@redhat.com>
> Subject: Re: [PATCH V8 1/6] qapi/net: Add IPFlowSpec and QMP command
> for COLO passthrough
>
> "Zhang, Chen" <chen.zh...@intel.com> writes:
>
> >> -----Original Message-----
> >> From: Markus Armbruster <arm...@redhat.com>
> >> Sent: Wednesday, June 16, 2021 2:04 PM
> >> To: Zhang, Chen <chen.zh...@intel.com>
> >> Cc: Lukas Straub <lukasstra...@web.de>; Daniel P.Berrangé
> >> <berra...@redhat.com>; Li Zhijian <lizhij...@cn.fujitsu.com>; Jason
> >> Wang <jasow...@redhat.com>; qemu-dev <qemu-devel@nongnu.org>;
> Dr.
> >> David Alan Gilbert <dgilb...@redhat.com>; Gerd Hoffmann
> >> <kra...@redhat.com>; Zhang Chen <zhangc...@gmail.com>; Eric Blake
> >> <ebl...@redhat.com>
> >> Subject: Re: [PATCH V8 1/6] qapi/net: Add IPFlowSpec and QMP
> command
> >> for COLO passthrough
> >>
> >> "Zhang, Chen" <chen.zh...@intel.com> writes:
> >>
> >> >> -----Original Message-----
> >> >> From: Markus Armbruster <arm...@redhat.com>
> >> >> Sent: Tuesday, June 15, 2021 10:43 PM
> >> >> To: Zhang, Chen <chen.zh...@intel.com>
> >> >> Cc: Jason Wang <jasow...@redhat.com>; qemu-dev <qemu-
> >> >> de...@nongnu.org>; Eric Blake <ebl...@redhat.com>; Dr. David Alan
> >> >> Gilbert <dgilb...@redhat.com>; Daniel P.Berrangé
> >> >> <berra...@redhat.com>; Gerd Hoffmann <kra...@redhat.com>; Li
> >> Zhijian
> >> >> <lizhij...@cn.fujitsu.com>; Lukas Straub <lukasstra...@web.de>;
> >> >> Zhang Chen <zhangc...@gmail.com>
> >> >> Subject: Re: [PATCH V8 1/6] qapi/net: Add IPFlowSpec and QMP
> >> command
> >> >> for COLO passthrough
> >> >>
> >> >> Zhang Chen <chen.zh...@intel.com> writes:
> >> >>
> >> >> > Since the real user scenario does not need COLO to monitor all
> >> >> > traffic.
> >> >> > Add colo-passthrough-add and colo-passthrough-del to maintain a
> >> >> > COLO network passthrough list. Add IPFlowSpec struct for all QMP
> commands.
> >> >> > All the fields of IPFlowSpec are optional.
> >> >> >
> >> >> > Signed-off-by: Zhang Chen <chen.zh...@intel.com>
> >> >> > ---
> >> >>
> >> >> The QAPI schema looks good to me, but the interface documentation
> >> >> is still not quite clear enough. To make progress, I'm going to
> >> >> make concrete suggestions wherever I can despite being quite
> >> >> clueless about the subject matter. Risks me writing something
> >> >> that's clearer, but wrong. Keep that in mind, please.
> >> >>
> >> >> > net/net.c | 10 +++++++
> >> >> > qapi/net.json | 74
> >> >> > +++++++++++++++++++++++++++++++++++++++++++++++++++
> >> >> > 2 files changed, 84 insertions(+)
> >> >> >
> >> >> > diff --git a/net/net.c b/net/net.c index 76bbb7c31b..f913e97983
> >> >> > 100644
> >> >> > --- a/net/net.c
> >> >> > +++ b/net/net.c
> >> >> > @@ -1195,6 +1195,16 @@ void qmp_netdev_del(const char *id,
> Error **errp)
> >> >> > }
> >> >> > }
> >> >> >
> >> >> > +void qmp_colo_passthrough_add(IPFlowSpec *spec, Error **errp)
> {
> >> >> > + /* TODO implement setup passthrough rule */ }
> >> >> > +
> >> >> > +void qmp_colo_passthrough_del(IPFlowSpec *spec, Error **errp) {
> >> >> > + /* TODO implement delete passthrough rule */ }
> >> >> > +
> >> >> > static void netfilter_print_info(Monitor *mon, NetFilterState *nf) {
> >> >> > char *str;
> >> >> > diff --git a/qapi/net.json b/qapi/net.json index
> >> >> > 7fab2e7cd8..91f2e1495a 100644
> >> >> > --- a/qapi/net.json
> >> >> > +++ b/qapi/net.json
> >> >> > @@ -7,6 +7,7 @@
> >> >> > ##
> >> >> >
> >> >> > { 'include': 'common.json' }
> >> >> > +{ 'include': 'sockets.json' }
> >> >> >
> >> >> > ##
> >> >> > # @set_link:
> >> >> > @@ -696,3 +697,76 @@
> >> >> > ##
> >> >> > { 'event': 'FAILOVER_NEGOTIATED',
> >> >> > 'data': {'device-id': 'str'} }
> >> >> > +
> >> >> > +##
> >> >> > +# @IPFlowSpec:
> >> >> > +#
> >> >> > +# IP flow specification.
> >> >> > +#
> >> >> > +# @protocol: Transport layer protocol like TCP/UDP, etc. The
> protocol is the
> >> >> > +# string instead of enum, because it can be passed to
> getprotobyname(3)
> >> >> > +# and avoid duplication with /etc/protocols.
> >> >>
> >> >> The rationale is good, but it doesn't really belong into the
> >> >> interface documentation. Suggest:
> >> >>
> >> >> # @protocol: Transport layer protocol like TCP/UDP, etc. This will
> >> >> be
> >> >> # passed to getprotobyname(3).
> >> >>
> >> >
> >> > OK.
> >> >
> >> >>
> >> >> > +#
> >> >> > +# @object-name: The @object-name means packet handler in
> Qemu. Because not
> >> >> > +# all the network packet must pass the colo-compare
> module,
> >> >> > +# the net-filters are same situation. There modules
> >> >> > attach to
> >> >> > +# netdev or chardev to work, VM can run multiple
> >> >> > modules
> >> >> > +# at the same time. So it needs the object-name to set
> >> >> > +# the effective module.
> >> >>
> >> >> I still don't understand this, and I'm too ignorant of COLO and
> >> >> networking to suggest improvements.
> >> >
> >> > Let me use qemu boot parameter to clear it.
> >> > For colo-compare, it needs chardev as the source to handle network
> packet.
> >> > -object colo-compare,id=comp0,primary_in=chardev-
> input0,secondary_in=chardev-input1,outdev=chardev-
> output0,iothread=iothread0.
> >> >
> >> > For net filters, it needs attached on netdev.
> >> > -object
> >> > filter-redirector,id=red0,netdev=hn0,queue=rx,outdev=chardev-
> output
> >> > 1 -object
> >> > filter-mirror,id=mirror0,netdev=hn0,queue=rx,outdev=chardev-
> output2
> >> >
> >> > And we can use -chardev socket combine the filter and the colo-
> compare.
> >> >
> >> > Back to the @object-name, One guest maybe have multi colo-compare
> as the same time, with different object name from different source.
> >> > So we need assign the IPFlowSpec to one object as the handler. Same
> as the net-filters.
> >> > Each object instance has its own passthrough list.
> >>
> >> So the @object-name here references one of the "packet handler
> objects"
> >> (colo-compare, filter-redirector, filter-mirror) by @id. Correct?
> >
> > Yes.
> >
> >>
> >> In other words, @object-name is the ID of a QOM object, and the QOM
> >> object must be of a certain kind (i.e. provide certain functionality).
> >> Correct?
> >
> > Yes.
>
> Got it.
>
> >> What exactly makes a QOM object a "packet handler object?"
> >>
> >
> > Firstly, the original object need have basic network packet input/output
> capability.
> > It's a good question, maybe we need add a flag in general object structure
> to show the capability.
>
> A QOM interface might fit the bill: a QOM type is a packet handler if and only
> if it implements the packet handler interface.
>
> >> Right now, the packet handler object types are colo-compare, filter-
> >> redirector, filter-mirror, and that's all. Correct?
> >
> > No, this series just make colo-compare become a packet handler, This is a
> beginning, I plan to make other filters support it.
>
> Okay.
>
> Are these other filters similarly related to COLO? I'm asking because the
> commands are called colo-passthrough-FOO. If this goes beyond COLO, we
> may want to name them differently.
No, net-filter is an independent module, although colo must use net-filter to
build colo-proxy.
I think we can change the name when enable net-filter support passthrough list.
>
> >> Another question the doc comment needs to answer: what happens
> when
> >> @object-name is absent?
> >
> > Please see the explanation below.
>
> You seem to consider making it mandatory there. My question would be
> moot then.
>
> >> >> Jason or David, perhaps?
> >> >>
> >> >> > +#
> >> >> > +# @source: Source address and port.
> >> >> > +#
> >> >> > +# @destination: Destination address and port.
> >> >> > +#
> >> >> > +# Since: 6.1
> >> >> > +##
> >> >> > +{ 'struct': 'IPFlowSpec',
> >> >> > + 'data': { '*protocol': 'str', '*object-name': 'str',
> >> >> > + '*source': 'InetSocketAddressBase',
> >> >> > + '*destination': 'InetSocketAddressBase' } }
> >> >> > +
> >> >> > +##
> >> >> > +# @colo-passthrough-add:
> >> >> > +#
> >> >> > +# Add passthrough entry IPFlowSpec to the COLO-compare
> instance.
> >> >> > +# The protocol and source/destination IP/ports are optional. if
> >> >> > +the user # only inputs part of the information, this will match all
> traffic.
> >> >>
> >> >> Actually, all arguments are optional.
> >> >>
> >> >> Suggest:
> >> >>
> >> >> # Add an entry to the COLO network passthrough list.
> >> >> # Absent protocol, host addresses and ports match anything.
> >> >>
> >> >> If there is more than one such list, then "to a COLO network
> passthrough list"
> >> >> instead.
> >> >
> >> > Yes, more than one list.
> >> >
> >> >>
> >> >> Still missing then: meaning of absent @object-name. Does it
> >> >> select the COLO network passthrough list, perhaps?
> >> >
> >> > Yes, Please see the explanation above. Each object instance has its own
> passthrough list.
> >>
> >> Got it now.
> >>
> >> >> > +#
> >> >> > +# Returns: Nothing on success
> >> >> > +#
> >> >> > +# Since: 6.1
> >> >> > +#
> >> >> > +# Example:
> >> >> > +#
> >> >> > +# -> { "execute": "colo-passthrough-add",
> >> >> > +# "arguments": { "protocol": "tcp", "object-name": "object0",
> >> >> > +# "source": {"host": "192.168.1.1", "port": "1234"},
> >> >> > +# "destination": {"host": "192.168.1.2", "port": "4321"} } }
> >> >> > +# <- { "return": {} }
> >> >> > +#
> >> >> > +##
> >> >> > +{ 'command': 'colo-passthrough-add', 'boxed': true,
> >> >> > + 'data': 'IPFlowSpec' }
> >> >> > +
> >> >> > +##
> >> >> > +# @colo-passthrough-del:
> >> >> > +#
> >> >> > +# Delete passthrough entry IPFlowSpec to the COLO-compare
> instance.
> >> >> > +# The protocol and source/destination IP/ports are optional. if
> >> >> > +the user # only inputs part of the information, this will match all
> traffic.
> >> >>
> >> >> I suspect this command doesn't actually match traffic, it matches
> >> >> entries added with colo-passthrough-add.
> >> >
> >> > Yes.
> >> >
> >> >>
> >> >> Can it delete more than one such entry?
> >> >>
> >> >
> >> > Currently no, but it easy to match one more entry to delete.
> >>
> >> If the passthrough list entries had some unique ID, we could refer to
> >> one entry by its ID. It's how things commonly work.
> >>
> >> Without an ID, we need to match by value, like you do. I can see
> >> three possible behaviors:
> >>
> >> 1. Select first entry that matches.
> >>
> >> 2. Select all entries that match.
> >>
> >> 3. If exactly one entry matches, select it.
> >>
> >> The second design choice is behavior when nothing gets selected:
> >>
> >> a. Silently do nothing
> >>
> >> b. Error
> >>
> >> Which one did you implement? My guess based on your answers is 1a.
> >
> > Re-think about it, If we want to match by value, we need know which
> object have the capability and search in each object passthrough list.
> > Obviously, we haven't such flag in object structure. So It more reasonable
> to make @object-name as a must at the beginning.
> > Because the passthrough list always in the network handler object. Maybe
> we need a global passthrough list for each guest to handle it in the future.
> > It will have two-level passthrough list to control network.
>
> I'm not sure I understand.
>
> If you make @object-name mandatory both for colo-passthrough-add and
> colo-passthrough-del, then we can simply use @object-name to find the
> object, check it implements the packet handler interface, use the packet
> handler interface to get its passthrough list, then add to / delete from that
> list.
Yes, I think so.
>
> If we find a use for making @object-name optional later, we can do so
> without breaking compatibility.
Yes, It still need current code as the base. Just need add a global passthrough
list.
Thanks
Chen
