smoketest: T9316: do not race the DHCP client when checking VRF membership

test_dhcp_vrf and test_dhcpv6_vrf resolved the DHCP client's PID, then read
the VRF's process list and asserted the PID appeared in it. The client
re-executes itself at moments of its own choosing, so between those two
steps it can come back with a new PID - the process is in the VRF, it simply
is not the process we asked about:

  AssertionError: '13502' not found in '14322  dhclient\n
                                        14324  dhclient-script\n
                                        14485  dhclient...'

Observed failing and passing on the same image, so it costs a rerun rather
than telling anyone anything.

get_process_cmdline() already fights the same race for the /proc read.
Resolve the PID and read the VRF's list as one step and retry, so a restart
costs a retry instead of a failure.

The probe itself was also loose: substring-matching the raw output of
"ip vrf pids <name>" lets a PID check be satisfied by the process name
column or by a longer PID containing ours. Add
vyos.utils.network.get_vrf_pids(), which parses the command's
"<pid>  <name>" lines into (pid, process_name) tuples and returns an empty
list for an unknown VRF, and compare the PID field as an int.

0 files changed, 0 insertions, 0 deletions