dnsdist xdp on 2 interfaces

[top-secrett]

I have server with 2 physical interfaces: ens1f0 for ipv4 and ens1f1 for ipv6
I run

python /opt/pdns/contrib/xdp.py --xsk --interface ens1f0
python /opt/pdns/contrib/xdp.py --xsk --interface ens1f1

And how can I configure dnsdist to run xsk on two interfaces? Config bellow doesn't work

function addListeners(i)
  xsk = newXsk({ifName="ens1f0", NIC_queue_id=i-1, frameNums=524288, xskMapPath="/sys/fs/bpf/dnsdist/xskmap"})
  addLocal("IPV4:53", {xskSocket=xsk, reusePort=true,})
end

function addListenersv6(i)
  xsk6 = newXsk({ifName="ens1f1", NIC_queue_id=i-1, frameNums=524288, xskMapPath="/sys/fs/bpf/dnsdist/xskmap"})
  addLocal("IPV6:53", {xskSocket=xsk6, reusePort=true})
end

function addServers()
  newServer({address="IP:53", name="ns1-node2", pool="current_dc", checkClass=DNSClass.CHAOS, checkName="version.bind", checkType="TXT", checkTimeout=2000, maxCheckFailures=3, checkInterval=3, mustResolve=true, useClientSubnet=true, rise=2,})
end

setUDPSocketBufferSizes(16777216,16777216)
addCapabilitiesToRetain("CAP_SYS_ADMIN")
addCapabilitiesToRetain("CAP_NET_ADMIN")

for i = 1,60 do
    addListeners(i)
    addListenersv6(i)
    addServers()
end

[top-secrett]

Sorry, I can't even run two scripts

python /opt/pdns/contrib/xdp.py --xsk --interface ens1f0
python /opt/pdns/contrib/xdp.py --xsk --interface ens1f1

Error when I run second:

Traceback (most recent call last):
  File "/tmp/contrib/./xdp.py", line 201, in <module>
    xdp.trace_print()
  File "/usr/lib/python3/dist-packages/bcc/__init__.py", line 1568, in trace_print
    line = self.trace_readline(nonblocking=False)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/bcc/__init__.py", line 1544, in trace_readline
    trace = self.trace_open(nonblocking)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/bcc/__init__.py", line 1495, in trace_open
    self.tracefile = open("%s/trace_pipe" % TRACEFS, "rb")
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [Errno 16] Device or resource busy: '/sys/kernel/debug/tracing/trace_pipe'

[rgacogne]

Ah, right, as far as I know no-one actually tried to do that yet so the tooling is probably not ready for it. I'll have a look later today.

[rgacogne]

I just added support for multiple interfaces in #15132. If you have the chance to test it that would be brilliant!

[top-secrett]

@rgacogne python /opt/pdns/contrib/xdp.py --xsk -i ens1f0 -i ens1f1
script tries to enable xsk additionally on default eth0

Enabling XSK (AF_XDP) on ens1f1..
Enabling XSK (AF_XDP) on eth0..
In file included from /virtual/main.c:1:
/opt/pdns/contrib/xdp.h:17:9: warning: 'memcpy' macro redefined [-Wmacro-redefined]
   17 | #define memcpy __builtin_memcpy
      |         ^
include/linux/fortify-string.h:652:9: note: previous definition is here
  652 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
      |         ^
1 warning generated.
bpf: Resolving device name to index: No such device
Traceback (most recent call last):
  File "/opt/pdns/contrib/xdp.py", line 131, in <module>
    xdp.attach_xdp(interface, fn, 0)
  File "/usr/lib/python3/dist-packages/bcc/__init__.py", line 950, in attach_xdp
    raise Exception("Failed to attach BPF to device %s: %s"
Exception: Failed to attach BPF to device b'eth0': No such device```

[rgacogne]

Oh, right, I guess I need to remove the default, will do in a second.

[rgacogne]

I pushed a new commit fixing it, thanks!

[top-secrett]

@rgacogne
If I delete default=['eth0'] it looks like it's working

parser.add_argument('--interface', '-i', type=str, action='append',

python /opt/pdns/contrib/xdp.py --xsk -i ens1f1 -i ens1f0
Enabling XSK (AF_XDP) on ens1f0..
Enabling XSK (AF_XDP) on ens1f1..
In file included from /virtual/main.c:1:
/opt/pdns/contrib/xdp.h:17:9: warning: 'memcpy' macro redefined [-Wmacro-redefined]
   17 | #define memcpy __builtin_memcpy
      |         ^
include/linux/fortify-string.h:652:9: note: previous definition is here
  652 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
      |         ^
1 warning generated.
Blocking ('192.0.2.1', 2)
Blocking ('2001:db8::1', 2)
Blocking ('192.0.1.1/24', 2)
Blocking ('2001:db8::1/128', 2)
Blocking ('localhost', 'A', 1)
Blocking ('test.com', '*', 2)
Filter is ready on ens1f0
Filter is ready on ens1f1

[rgacogne]

Thanks a lot for the feedback, much appreciated!