selftests: mptcp: add wrapper for showing addrs

This patch implemented a new function named pm_nl_show_endpoints(), wrapped
the PM netlink commands 'ip mptcp endpoint show' and 'pm_nl_ctl dump' in
it, used a new argument 'ip_mptcp' to choose which one to use to show all
the PM endpoints.

Used this wrapper in do_transfer() instead of using the pm_nl_ctl commands
directly.

The original 'pos+=5' in the remoing tests only works for the output of
'pm_nl_ctl show':

  id 1 flags subflow 10.0.1.1

It doesn't work for the output of 'ip mptcp endpoint show':

  10.0.1.1 id 1 subflow

So implemented a more flexible approach to get the address ID from the PM
dump output to fit for both commands.
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -365,6 +365,17 @@ pm_nl_flush_endpoint()
 	fi
 }
 
+pm_nl_show_endpoints()
+{
+	local ns=$1
+
+	if [ $ip_mptcp -eq 1 ]; then
+		ip -n $ns mptcp endpoint show
+	else
+		ip netns exec $ns ./pm_nl_ctl dump
+	fi
+}
+
 do_transfer()
 {
 	listener_ns="$1"
@@ -472,20 +483,25 @@ do_transfer()
 	elif [ $addr_nr_ns1 -lt 0 ]; then
 		let rm_nr_ns1=-addr_nr_ns1
 		if [ $rm_nr_ns1 -lt 8 ]; then
-			counter=1
-			pos=1
-			dump=(`ip netns exec ${listener_ns} ./pm_nl_ctl dump`)
-			if [ ${#dump[@]} -gt 0 ]; then
-				while [ $counter -le $rm_nr_ns1 ]
-				do
-					id=${dump[$pos]}
+			counter=0
+			pm_nl_show_endpoints ${listener_ns} | while read line; do
+				local arr=($line)
+				local nr=0
+
+				for i in ${arr[@]}; do
+					if [ $i = "id" ]; then
+						if [ $counter -eq $rm_nr_ns1 ]; then
+							break
+						fi
+						id=${arr[$nr+1]}
 						rm_addr=$(rm_addr_count ${connector_ns})
 						pm_nl_del_endpoint ${listener_ns} $id
 						wait_rm_addr ${connector_ns} ${rm_addr}
 						let counter+=1
-					let pos+=5
-				done
 					fi
+					let nr+=1
+				done
+			done
 		elif [ $rm_nr_ns1 -eq 8 ]; then
 			pm_nl_flush_endpoint ${listener_ns}
 		elif [ $rm_nr_ns1 -eq 9 ]; then
@@ -520,21 +536,27 @@ do_transfer()
 	elif [ $addr_nr_ns2 -lt 0 ]; then
 		let rm_nr_ns2=-addr_nr_ns2
 		if [ $rm_nr_ns2 -lt 8 ]; then
-			counter=1
-			pos=1
-			dump=(`ip netns exec ${connector_ns} ./pm_nl_ctl dump`)
-			if [ ${#dump[@]} -gt 0 ]; then
-				while [ $counter -le $rm_nr_ns2 ]
-				do
-					# rm_addr are serialized, allow the previous one to complete
-					id=${dump[$pos]}
+			counter=0
+			pm_nl_show_endpoints ${connector_ns} | while read line; do
+				local arr=($line)
+				local nr=0
+
+				for i in ${arr[@]}; do
+					if [ $i = "id" ]; then
+						if [ $counter -eq $rm_nr_ns2 ]; then
+							break
+						fi
+						# rm_addr are serialized, allow the previous one to
+						# complete
+						id=${arr[$nr+1]}
 						rm_addr=$(rm_addr_count ${listener_ns})
 						pm_nl_del_endpoint ${connector_ns} $id
 						wait_rm_addr ${listener_ns} ${rm_addr}
 						let counter+=1
-					let pos+=5
-				done
 					fi
+					let nr+=1
+				done
+			done
 		elif [ $rm_nr_ns2 -eq 8 ]; then
 			pm_nl_flush_endpoint ${connector_ns}
 		elif [ $rm_nr_ns2 -eq 9 ]; then
@@ -551,7 +573,7 @@ do_transfer()
 	if [ ! -z $sflags ]; then
 		sleep 1
 		for netns in "$ns1" "$ns2"; do
-			ip netns exec $netns ./pm_nl_ctl dump | while read line; do
+			pm_nl_show_endpoints $netns | while read line; do
 				local arr=($line)
 				local addr
 				local port=0