Re: [PATCH] test: Select first reported IPv6 address for guest/host comparison

[Stefano Brivio <sbrivio@redhat.com>]

On Mon, 11 Dec 2023 13:05:20 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Fri, Dec 08, 2023 at 06:49:32PM +0100, Stefano Brivio wrote:
> > If we run passt nested (a guest connected via passt to a guest
> > connected via passt to the host), the first guest (L1) typically has
> > two IPv6 addresses: one formed from the prefix assigned via SLAAC,
> > and another one assigned via DHCPv6 (to match the address on the
> > host).  
> 
> Hmm... it can't be just that there are multible IPv6 addresses here
> that's the problem.  I usually have multiple IPv6 unicast addresses on
> my laptop (one for the wifi, one for wired) and I already got that
> working.
> 
> Possibly it's that there are multiple addresses on the same interface?

Yes, the guest has a single interface and multiple addresses for it,
I'll change the commit message.

> But see below..
> 
> > When we select addresses for comparison, in this case, we have
> > multiple global unicast addresses. Selecting the first reported one
> > on both host and guest is not entirely correct (in theory, the order
> > might differ), but works reasonably well.  
> 
> That approach seems good, in principle
> 
> > Use the trick from 5beef085978e ("test: Only select a single
> > interface or gateway in tests") to ask jq(1) for the first address
> > returned by the query.  
> 
> But that patch was selecting gateways, not local addresses, so I don't
> think  the same syntax makes sense.
> 
> > 
> > Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
> > ---
> >  test/passt/dhcp       | 8 ++++----
> >  test/passt/ndp        | 4 ++--
> >  test/pasta/dhcp       | 8 ++++----
> >  test/pasta/ndp        | 4 ++--
> >  test/two_guests/basic | 6 +++---
> >  5 files changed, 15 insertions(+), 15 deletions(-)
> > 
> > diff --git a/test/passt/dhcp b/test/passt/dhcp
> > index 7272755..b428064 100644
> > --- a/test/passt/dhcp
> > +++ b/test/passt/dhcp
> > @@ -22,8 +22,8 @@ check	[ -n "__IFNAME__" ]
> >  
> >  test	DHCP: address
> >  guest	/sbin/dhclient -4 __IFNAME__
> > -gout	ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local'
> > -hout	HOST_ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME__").addr_info[0].local'
> > +gout	ADDR ip -j -4 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[0].local] | .[0]'
> > +hout	HOST_ADDR ip -j -4 addr show|jq -rM '[.[] | select(.ifname == "__HOST_IFNAME__").addr_info[0].local] | .[0]'  
> 
> I'm confused by this.  The 'addr_info[0]' should already be selecting
> the first address from each interface, so the outer '.[0]' would only
> be doing something if multiple interfaces are selected, and I'm not
> quite sure why that would happen.
> 
> In fact, I suspect this one was right all along... 

Right, this doesn't make sense, I just went too far with the copy and
paste. Same as for the pasta/dhcp change below. There are actually no
issues with IPv4. I'll drop those.

> >  check	[ "__ADDR__" = "__HOST_ADDR__" ]
> >  
> >  test	DHCP: route
> > @@ -49,8 +49,8 @@ check	[ "__SEARCH__" = "__HOST_SEARCH__" ]
> >  
> >  test	DHCPv6: address
> >  guest	/sbin/dhclient -6 __IFNAME__
> > -gout	ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local'
> > -hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
> > +gout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local] | .[0]'
> > +hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname ==
> >  "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local]
> >  | .[0]'  
> 
> ... but this one isn't, because it is .addr_info[].  Previously the
> second 'select' has picked out only one, but not in this situation.
> So here the change makes sense to me.

Here we want to use .addr_info[] because we want to filter further on
prefixlen or scope. But once we've done that, if we have two addresses,
we have to pick one.

> >  check	[ "__ADDR6__" = "__HOST_ADDR6__" ]
> >  
> >  test	DHCPv6: route
> > diff --git a/test/passt/ndp b/test/passt/ndp
> > index 6de4081..7b2dbfe 100644
> > --- a/test/passt/ndp
> > +++ b/test/passt/ndp
> > @@ -21,9 +21,9 @@ hout	HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").d
> >  check	[ -n "__IFNAME__" ]
> >  
> >  test	SLAAC: prefix
> > -gout	ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local'
> > +gout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local] | .[0]'
> >  gout	PREFIX6 sipcalc __ADDR6__/64 | grep prefix | cut -d' ' -f4
> > -hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
> > +hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local] | .[0]'
> >  hout	HOST_PREFIX6 sipcalc __HOST_ADDR6__/64 | grep prefix | cut -d' ' -f4
> >  check	[ "__PREFIX6__" = "__HOST_PREFIX6__" ]
> >  
> > diff --git a/test/pasta/dhcp b/test/pasta/dhcp
> > index 309001b..b4f6f60 100644
> > --- a/test/pasta/dhcp
> > +++ b/test/pasta/dhcp
> > @@ -20,8 +20,8 @@ check	[ -n "__IFNAME__" ]
> >  
> >  test	DHCP: address
> >  ns	/sbin/dhclient -4 --no-pid __IFNAME__
> > -nsout	ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local'
> > -hout	HOST_ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local'
> > +nsout	ADDR ip -j -4 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[0].local] | .[0]'
> > +hout	HOST_ADDR ip -j -4 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[0].local] | .[0]'
> >  check	[ __ADDR__ = __HOST_ADDR__ ]
> >  
> >  test	DHCP: route
> > @@ -36,8 +36,8 @@ check	[ __MTU__ = 65520 ]
> >  test	DHCPv6: address
> >  ns	/sbin/dhclient -6 --no-pid __IFNAME__
> >  hout	HOST_IFNAME6 ip -j -6 route show|jq -rM '[.[] | select(.dst == "default").dev] | .[0]'
> > -nsout	ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local'
> > -hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
> > +nsout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.prefixlen == 128).local] | .[0]'
> > +hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local] | .[0]'
> >  check	[ __ADDR6__ = __HOST_ADDR6__ ]
> >  
> >  test	DHCPv6: route
> > diff --git a/test/pasta/ndp b/test/pasta/ndp
> > index bb33110..2a8afe6 100644
> > --- a/test/pasta/ndp
> > +++ b/test/pasta/ndp
> > @@ -21,9 +21,9 @@ ns	ip link set dev __IFNAME__ up
> >  sleep	2
> >  
> >  test	SLAAC: prefix
> > -nsout	ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local'
> > +nsout	ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global" and .prefixlen == 64).local] | .[0]'
> >  nsout	PREFIX6 sipcalc __ADDR6__/64 | grep prefix | cut -d' ' -f4
> > -hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global").local'
> > +hout	HOST_ADDR6 ip -j -6 addr show|jq -rM ['.[] | select(.ifname == "__IFNAME__").addr_info[] | select(.scope == "global").local] | .[0]'
> >  hout	HOST_PREFIX6 sipcalc __HOST_ADDR6__/64 | grep prefix | cut -d' ' -f4
> >  check	[ "__PREFIX6__" = "__HOST_PREFIX6__" ]
> >  
> > diff --git a/test/two_guests/basic b/test/two_guests/basic
> > index 09fbd3e..fa0608b 100644
> > --- a/test/two_guests/basic
> > +++ b/test/two_guests/basic
> > @@ -39,9 +39,9 @@ test	DHCPv6: addresses
> >  sleep	2
> >  guest1	/sbin/dhclient -6 __IFNAME1__
> >  guest2	/sbin/dhclient -6 __IFNAME2__
> > -g1out	ADDR1_6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME1__").addr_info[] | select(.prefixlen == 128).local'
> > -g2out	ADDR2_6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__IFNAME2__").addr_info[] | select(.prefixlen == 128).local'
> > -hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local'
> > +g1out	ADDR1_6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME1__").addr_info[] | select(.prefixlen == 128).local] | .[0]'
> > +g2out	ADDR2_6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__IFNAME2__").addr_info[] | select(.prefixlen == 128).local] | .[0]'
> > +hout	HOST_ADDR6 ip -j -6 addr show|jq -rM '[.[] | select(.ifname == "__HOST_IFNAME6__").addr_info[] | select(.scope == "global").local] | .[0]'
> >  check	[ "__ADDR1_6__" = "__HOST_ADDR6__" ]
> >  check	[ "__ADDR2_6__" = "__HOST_ADDR6__" ]

-- 
Stefano