selftests: forwarding: Test IPv4 weighted nexthops

Use different weights for the multipath route configured on the first
router and check that the different flows generated by the first host
are distributed according to the provided weights.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/lib.sh

@@ -113,6 +113,13 @@ log_test()
 	return 0
 }
 
+log_info()
+{
+	local msg=$1
+
+	echo "INFO: $msg"
+}
+
 setup_wait()
 {
 	for i in $(eval echo {1..$NUM_NETIFS}); do
@@ -256,6 +263,13 @@ master_name_get()
 	ip -j link show dev $if_name | jq -r '.[]["master"]'
 }
 
+link_stats_tx_packets_get()
+{
+       local if_name=$1
+
+       ip -j -s link show dev $if_name | jq '.[]["stats64"]["tx"]["packets"]'
+}
+
 bridge_ageing_time_get()
 {
 	local bridge=$1

tools/testing/selftests/net/forwarding/router_multipath.sh

@@ -158,6 +158,82 @@ router2_destroy()
 	vrf_destroy "vrf-r2"
 }
 
+multipath_eval()
+{
+       local weight_rp12=$1
+       local weight_rp13=$2
+       local packets_rp12=$3
+       local packets_rp13=$4
+       local weights_ratio packets_ratio diff
+
+       RET=0
+
+       if [[ "$weight_rp12" -gt "$weight_rp13" ]]; then
+               weights_ratio=$(echo "scale=2; $weight_rp12 / $weight_rp13" \
+		       | bc -l)
+               packets_ratio=$(echo "scale=2; $packets_rp12 / $packets_rp13" \
+		       | bc -l)
+       else
+               weights_ratio=$(echo "scale=2; $weight_rp13 / $weight_rp12" | \
+		       bc -l)
+               packets_ratio=$(echo "scale=2; $packets_rp13 / $packets_rp12" | \
+		       bc -l)
+       fi
+
+       diff=$(echo $weights_ratio - $packets_ratio | bc -l)
+       diff=${diff#-}
+
+       test "$(echo "$diff / $weights_ratio > 0.1" | bc -l)" -eq 0
+       check_err $? "Too large discrepancy between expected and measured ratios"
+       log_test "Multipath"
+       log_info "Expected ratio $weights_ratio Measured ratio $packets_ratio"
+}
+
+multipath4_test()
+{
+       local weight_rp12=$1
+       local weight_rp13=$2
+       local t0_rp12 t0_rp13 t1_rp12 t1_rp13
+       local packets_rp12 packets_rp13
+       local hash_policy
+
+       # Transmit multiple flows from h1 to h2 and make sure they are
+       # distributed between both multipath links (rp12 and rp13)
+       # according to the configured weights.
+       hash_policy=$(sysctl -n net.ipv4.fib_multipath_hash_policy)
+       sysctl -q -w net.ipv4.fib_multipath_hash_policy=1
+       ip route replace 198.51.100.0/24 vrf vrf-r1 \
+               nexthop via 169.254.2.22 dev $rp12 weight $weight_rp12 \
+               nexthop via 169.254.3.23 dev $rp13 weight $weight_rp13
+
+       t0_rp12=$(link_stats_tx_packets_get $rp12)
+       t0_rp13=$(link_stats_tx_packets_get $rp13)
+
+       ip vrf exec vrf-h1 $MZ -q -p 64 -A 192.0.2.2 -B 198.51.100.2 \
+	       -d 1msec -t udp "sp=1024,dp=0-32768"
+
+       t1_rp12=$(link_stats_tx_packets_get $rp12)
+       t1_rp13=$(link_stats_tx_packets_get $rp13)
+
+       let "packets_rp12 = $t1_rp12 - $t0_rp12"
+       let "packets_rp13 = $t1_rp13 - $t0_rp13"
+       multipath_eval $weight_rp12 $weight_rp13 $packets_rp12 $packets_rp13
+
+       # Restore settings.
+       ip route replace 198.51.100.0/24 vrf vrf-r1 \
+               nexthop via 169.254.2.22 dev $rp12 \
+               nexthop via 169.254.3.23 dev $rp13
+       sysctl -q -w net.ipv4.fib_multipath_hash_policy=$hash_policy
+}
+
+multipath_test()
+{
+	log_info "Running IPv4 multipath tests"
+	multipath4_test 1 1
+	multipath4_test 2 1
+	multipath4_test 11 45
+}
+
 setup_prepare()
 {
 	h1=${NETIFS[p1]}
@@ -205,5 +281,6 @@ setup_wait
 
 ping_test $h1 198.51.100.2
 ping6_test $h1 2001:db8:2::2
+multipath_test
 
 exit $EXIT_STATUS