selftests: netfilter: conntrack_sctp_collision.sh: move to lib.sh infra

While at it, address warnings generated by shellcheck and fix following
minor issues:

 - some distros place netem in 'extra' modules package, so add a skip check for netem-attach
   failure.
 - tc prints a warning for the 100mbit class:
   "Warning: sch_htb: quantum of class 10001 is big. Consider r2q change."
   Silence this by increasing the divisor.
Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20240411233624.8129-7-fw@strlen.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/netfilter/conntrack_sctp_collision.sh

@@ -12,69 +12,67 @@
 #
 # TOPO: SERVER_NS (link0)<--->(link1) ROUTER_NS (link2)<--->(link3) CLIENT_NS
 
-CLIENT_NS=$(mktemp -u client-XXXXXXXX)
+source lib.sh
+
 CLIENT_IP="198.51.200.1"
 CLIENT_PORT=1234
 
-SERVER_NS=$(mktemp -u server-XXXXXXXX)
 SERVER_IP="198.51.100.1"
 SERVER_PORT=1234
 
-ROUTER_NS=$(mktemp -u router-XXXXXXXX)
 CLIENT_GW="198.51.200.2"
 SERVER_GW="198.51.100.2"
 
 # setup the topo
 setup() {
-	ip net add $CLIENT_NS
-	ip net add $SERVER_NS
-	ip net add $ROUTER_NS
-	ip -n $SERVER_NS link add link0 type veth peer name link1 netns $ROUTER_NS
-	ip -n $CLIENT_NS link add link3 type veth peer name link2 netns $ROUTER_NS
+	setup_ns CLIENT_NS SERVER_NS ROUTER_NS
+	ip -n "$SERVER_NS" link add link0 type veth peer name link1 netns "$ROUTER_NS"
+	ip -n "$CLIENT_NS" link add link3 type veth peer name link2 netns "$ROUTER_NS"
 
-	ip -n $SERVER_NS link set link0 up
-	ip -n $SERVER_NS addr add $SERVER_IP/24 dev link0
-	ip -n $SERVER_NS route add $CLIENT_IP dev link0 via $SERVER_GW
+	ip -n "$SERVER_NS" link set link0 up
+	ip -n "$SERVER_NS" addr add $SERVER_IP/24 dev link0
+	ip -n "$SERVER_NS" route add $CLIENT_IP dev link0 via $SERVER_GW
 
-	ip -n $ROUTER_NS link set link1 up
-	ip -n $ROUTER_NS link set link2 up
-	ip -n $ROUTER_NS addr add $SERVER_GW/24 dev link1
-	ip -n $ROUTER_NS addr add $CLIENT_GW/24 dev link2
-	ip net exec $ROUTER_NS sysctl -wq net.ipv4.ip_forward=1
+	ip -n "$ROUTER_NS" link set link1 up
+	ip -n "$ROUTER_NS" link set link2 up
+	ip -n "$ROUTER_NS" addr add $SERVER_GW/24 dev link1
+	ip -n "$ROUTER_NS" addr add $CLIENT_GW/24 dev link2
+	ip net exec "$ROUTER_NS" sysctl -wq net.ipv4.ip_forward=1
 
-	ip -n $CLIENT_NS link set link3 up
-	ip -n $CLIENT_NS addr add $CLIENT_IP/24 dev link3
-	ip -n $CLIENT_NS route add $SERVER_IP dev link3 via $CLIENT_GW
+	ip -n "$CLIENT_NS" link set link3 up
+	ip -n "$CLIENT_NS" addr add $CLIENT_IP/24 dev link3
+	ip -n "$CLIENT_NS" route add $SERVER_IP dev link3 via $CLIENT_GW
 
 	# simulate the delay on OVS upcall by setting up a delay for INIT_ACK with
 	# tc on $SERVER_NS side
-	tc -n $SERVER_NS qdisc add dev link0 root handle 1: htb
-	tc -n $SERVER_NS class add dev link0 parent 1: classid 1:1 htb rate 100mbit
-	tc -n $SERVER_NS filter add dev link0 parent 1: protocol ip u32 match ip protocol 132 \
+	tc -n "$SERVER_NS" qdisc add dev link0 root handle 1: htb r2q 64
+	tc -n "$SERVER_NS" class add dev link0 parent 1: classid 1:1 htb rate 100mbit
+	tc -n "$SERVER_NS" filter add dev link0 parent 1: protocol ip u32 match ip protocol 132 \
 		0xff match u8 2 0xff at 32 flowid 1:1
-	tc -n $SERVER_NS qdisc add dev link0 parent 1:1 handle 10: netem delay 1200ms
+	if ! tc -n "$SERVER_NS" qdisc add dev link0 parent 1:1 handle 10: netem delay 1200ms; then
+		echo "SKIP: Cannot add netem qdisc"
+		exit $ksft_skip
+	fi
 
 	# simulate the ctstate check on OVS nf_conntrack
-	ip net exec $ROUTER_NS iptables -A FORWARD -m state --state INVALID,UNTRACKED -j DROP
-	ip net exec $ROUTER_NS iptables -A INPUT -p sctp -j DROP
+	ip net exec "$ROUTER_NS" iptables -A FORWARD -m state --state INVALID,UNTRACKED -j DROP
+	ip net exec "$ROUTER_NS" iptables -A INPUT -p sctp -j DROP
 
 	# use a smaller number for assoc's max_retrans to reproduce the issue
-	modprobe sctp
-	ip net exec $CLIENT_NS sysctl -wq net.sctp.association_max_retrans=3
+	modprobe -q sctp
+	ip net exec "$CLIENT_NS" sysctl -wq net.sctp.association_max_retrans=3
 }
 
 cleanup() {
-	ip net exec $CLIENT_NS pkill sctp_collision 2>&1 >/dev/null
-	ip net exec $SERVER_NS pkill sctp_collision 2>&1 >/dev/null
-	ip net del "$CLIENT_NS"
-	ip net del "$SERVER_NS"
-	ip net del "$ROUTER_NS"
+	ip net exec "$CLIENT_NS" pkill sctp_collision >/dev/null 2>&1
+	ip net exec "$SERVER_NS" pkill sctp_collision >/dev/null 2>&1
+	cleanup_all_ns
 }
 
 do_test() {
-	ip net exec $SERVER_NS ./sctp_collision server \
+	ip net exec "$SERVER_NS" ./sctp_collision server \
 		$SERVER_IP $SERVER_PORT $CLIENT_IP $CLIENT_PORT &
-	ip net exec $CLIENT_NS ./sctp_collision client \
+	ip net exec "$CLIENT_NS" ./sctp_collision client \
 		$CLIENT_IP $CLIENT_PORT $SERVER_IP $SERVER_PORT
 }