Hi Adrian,

On Sat, Apr 1, 2023 at 12:39 AM Adrian Moreno <[email protected]> wrote:
>
> Hi Wan,
>
> Thanks for submitting this patch.
>
> On 11/18/22 09:13, Wan Junjie wrote:
> > According to the ovs-fields manpage, 'TLVs must be ordered so that
> > a field’s prerequisites are satisfied before if is parsed'.
>
>
> I believe this sentence is talking about the binary Openflow (>1.2) format 
> where
> match fields are encoded in TLV.
>
> The way we represent flow matches in human-readable strings (for ovs-ofctl) is
> more flexible, allowing the user to express the matches in any arbitrary 
> order.
> For example, we could add a flow such as:
> "tcp_src=255,ip_src=1.1.1.1,ip,eth_src=ca:fe:ca:fe:ca:fe,tcp,actions=drop"
>
> which is clearly in a very weird order, but if we looked at the wire we'd see
> the TLV sections of the OFP packet are in the right order.
>
> > However, a match pattern like 'tcp,ipv6' can be parsed as 'tcp6',
> > meanwhile 'ipv6,tcp' is parsed as 'tcp'. So a limitation here make
> > sure that the order should be respected.
> >
>
> I understand this might be a bit confusing.
> Firstly, according to the ovs-fields(7) these are the meanings of the 
> shorthands:
>
> ip:   eth_type=0x0800,
> ipv6: eth_type=0x86dd
> tcp:  eth_type=0x0800,ip_proto=6
> tcp6: eth_type=0x86dd,ip_proto=6
>
> If we expand the shorthands:
>
> "tcp,ipv6" == "eth_type=0x0800,ip_proto=6,eth_type=0x86dd"
> "ipv6,tcp" == "eth_type=0x86dd,eth_type=0x0800,ip_proto=6"
>
> So the last "eth_type" match prevails.

Thanks for your clarification.
I saw the shorthands. IMHO flexibility input should not have any side
effect over correctness.
At least we should print a reminder to the user. Or add some documents instead?


Regards,
Wan Junjie

>
> > Signed-off-by: Wan Junjie <[email protected]>
> > ---
> >   lib/ofp-flow.c        |  3 +++
> >   tests/ofproto-dpif.at |  8 ++++----
> >   tests/ovs-ofctl.at    | 15 +++++++++++++++
> >   3 files changed, 22 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/ofp-flow.c b/lib/ofp-flow.c
> > index 3bc744f78..db9b75c7b 100644
> > --- a/lib/ofp-flow.c
> > +++ b/lib/ofp-flow.c
> > @@ -1580,6 +1580,9 @@ parse_ofp_str__(struct ofputil_flow_mod *fm, int 
> > command, char *string,
> >           char *error = NULL;
> >
> >           if (ofp_parse_protocol(name, &p)) {
> > +            if (match.flow.nw_proto) {
> > +                return xstrdup("TLVs must be ordered");
> > +            }
> >               match_set_dl_type(&match, htons(p->dl_type));
> >               if (p->nw_proto) {
> >                   match_set_nw_proto(&match, p->nw_proto);
> > diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
> > index 728243183..a4a7ab5fb 100644
> > --- a/tests/ofproto-dpif.at
> > +++ b/tests/ofproto-dpif.at
> > @@ -11629,14 +11629,14 @@ table=1,priority=1,action=drop
> >   dnl
> >   dnl Table 2
> >   dnl
> > -table=2,priority=10,in_port=1,tcp,ct_zone=1,ct_state=+trk+new,tcp,action=ct(commit,zone=1),ct(table=3,zone=2)
> > -table=2,priority=10,in_port=1,tcp,ct_zone=1,ct_state=+trk+est,tcp,action=ct(table=3,zone=2)
> > +table=2,priority=10,in_port=1,tcp,ct_zone=1,ct_state=+trk+new,action=ct(commit,zone=1),ct(table=3,zone=2)
> > +table=2,priority=10,in_port=1,tcp,ct_zone=1,ct_state=+trk+est,action=ct(table=3,zone=2)
> >   table=2,priority=1,action=drop
> >   dnl
> >   dnl Table 3
> >   dnl
> > -table=3,priority=10,in_port=1,tcp,ct_zone=2,ct_state=+trk+new,tcp,action=ct(commit,zone=2),4
> > -table=3,priority=10,in_port=1,tcp,ct_zone=2,ct_state=+trk+est,tcp,action=3
> > +table=3,priority=10,in_port=1,tcp,ct_zone=2,ct_state=+trk+new,action=ct(commit,zone=2),4
> > +table=3,priority=10,in_port=1,tcp,ct_zone=2,ct_state=+trk+est,action=3
> >   table=2,priority=1,action=drop
> >   ])
> >
> > diff --git a/tests/ovs-ofctl.at b/tests/ovs-ofctl.at
> > index a8934051e..b933924b8 100644
> > --- a/tests/ovs-ofctl.at
> > +++ b/tests/ovs-ofctl.at
> > @@ -381,6 +381,21 @@ do
> >   done
> >   AT_CLEANUP
> >
> > +AT_SETUP([ovs-ofctl parse-flow with protocol order])
> > +for test_case in \
> > +    'tcp,ip' \
> > +    'tcp,ipv6' \
> > +    'udp,ip' \
> > +    'udp,ip6'
> > +do
> > +    set $test_case
> > +    field=$1
> > +    AT_CHECK_UNQUOTED([ovs-ofctl parse-flow "$field,actions=drop"], [1], 
> > [],
> > +[ovs-ofctl: TLVs must be ordered
> > +])
> > +done
> > +AT_CLEANUP
> > +
> >   AT_SETUP([ovs-ofctl action inconsistency (OpenFlow 1.1)])
> >   OVS_VSWITCHD_START
> >   add_of_ports br0 1 2 3
>
> --
> Adrián Moreno
>
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