Refactored the setup of nft rulesets, now it is possible to set up an
SNAT or DNAT-only ruleset for future tests.
Presented the testcase function to test passive or active modes.

Signed-off-by: Andrii Melnychenko <a.melnychenko@vyos.io>
---
 tests/shell/testcases/packetpath/nat_ftp | 86 +++++++++++++++---------
 1 file changed, 53 insertions(+), 33 deletions(-)

diff --git a/tests/shell/testcases/packetpath/nat_ftp b/tests/shell/testcases/packetpath/nat_ftp
index d0faf2ef..bc116f6e 100755
--- a/tests/shell/testcases/packetpath/nat_ftp
+++ b/tests/shell/testcases/packetpath/nat_ftp
@@ -77,7 +77,7 @@ ip -net $S route add ${ip_rc}/64 via ${ip_rs} dev s_r
 ip netns exec $C ping -q -6 ${ip_sr} -c1 > /dev/null
 assert_pass "topo initialization"
 
-reload_ruleset()
+reload_ruleset_base()
 {
 	ip netns exec $R conntrack -F 2> /dev/null
 	ip netns exec $R $NFT -f - <<-EOF
@@ -87,12 +87,6 @@ reload_ruleset()
 			type "ftp" protocol tcp;
 		}
 
-		chain PRE-dnat {
-			type nat hook prerouting priority dstnat; policy accept;
-			# Dnat the control connection, data connection will be automaticly NATed.
-			ip6 daddr ${ip_rc} counter ip6 nexthdr tcp tcp dport 2121 counter dnat ip6 to [${ip_sr}]:21
-		}
-
 		chain PRE-aftnat {
 			type filter hook prerouting priority 350; policy drop;
 			iifname r_c tcp dport 21 ct state new ct helper set "ftp-standard" counter accept
@@ -111,14 +105,43 @@ reload_ruleset()
 			ip6 nexthdr tcp ct state established counter accept
 			ip6 nexthdr tcp ct state related     counter log accept
 		}
+	}
+	EOF
+	assert_pass "apply ftp helper base ruleset"
+}
+
+load_dnat()
+{
+	ip netns exec $R $NFT -f - <<-EOF
+	table ip6 ftp_helper_nat_test {
+		chain PRE-dnat {
+			type nat hook prerouting priority dstnat; policy accept;
+			# Dnat the control connection, data connection will be automaticly NATed.
+			ip6 daddr ${ip_rc} counter ip6 nexthdr tcp tcp dport 2121 counter dnat ip6 to [${ip_sr}]:21
+		}
+	}
+	EOF
+	assert_pass "apply ftp helper DNAT ruleset"
+}
 
+load_snat()
+{
+	ip netns exec $R $NFT -f - <<-EOF
+	table ip6 ftp_helper_nat_test {
 		chain POST-srcnat {
 			type nat hook postrouting priority srcnat; policy accept;
 			ip6 daddr ${ip_sr} ip6 nexthdr tcp tcp dport 21 counter snat ip6 to [${ip_rs}]:16500
 		}
 	}
 	EOF
-	assert_pass "apply ftp helper ruleset"
+	assert_pass "apply ftp helper SNAT ruleset"
+}
+
+reload_ruleset()
+{
+	reload_ruleset_base
+	load_dnat
+	load_snat
 }
 
 dd if=/dev/urandom of="$INFILE" bs=4096 count=1 2>/dev/null
@@ -141,38 +164,35 @@ wait_local_port_listen $S 21 tcp
 ip netns exec $S ss -6ltnp | grep -q '*:21'
 assert_pass "start vsftpd server"
 
+test_case()
+{
+	tag=$1
+	ftp_ip_and_port=$2
+	client_ip_to_check=$3
+	additional_curl_options=$4
+
+	ip netns exec $S tcpdump -q --immediate-mode -Ui s_r -w ${PCAP} 2> /dev/null &
+	pid=$!
+	sleep 0.5
+	ip netns exec $C curl ${additional_curl_options} --no-progress-meter --connect-timeout 5 ftp://${ftp_ip_and_port}/$(basename $INFILE) -o $OUTFILE
+	assert_pass "curl ftp "${tag}
+
+	cmp "$INFILE" "$OUTFILE"
+	assert_pass "FTP "${tag}": The input and output files remain the same when traffic passes through NAT."
+
+	kill $pid; sync
+	tcpdump -nnr ${PCAP} src ${client_ip_to_check} and dst ${ip_sr} 2>&1 |grep -q FTP
+	assert_pass "assert FTP traffic NATed"
+}
 
 # test passive mode
 reload_ruleset
-ip netns exec $S tcpdump -q --immediate-mode -Ui s_r -w ${PCAP} 2> /dev/null &
-pid=$!
-sleep 0.5
-ip netns exec $C curl --no-progress-meter --connect-timeout 5 ftp://[${ip_rc}]:2121/$(basename $INFILE) -o $OUTFILE
-assert_pass "curl ftp passive mode "
-
-cmp "$INFILE" "$OUTFILE"
-assert_pass "FTP Passive mode: The input and output files remain the same when traffic passes through NAT."
-
-kill $pid; sync
-tcpdump -nnr ${PCAP} src ${ip_rs} and dst ${ip_sr} 2>&1 |grep -q FTP
-assert_pass "assert FTP traffic NATed"
+test_case "Passive mode" [${ip_rc}]:2121 ${ip_rs}
 
 
 # test active mode
 reload_ruleset
-
-ip netns exec $S tcpdump -q --immediate-mode -Ui s_r -w ${PCAP} 2> /dev/null &
-pid=$!
-sleep 0.5
-ip netns exec $C curl --no-progress-meter -P - --connect-timeout 5 ftp://[${ip_rc}]:2121/$(basename $INFILE) -o $OUTFILE
-assert_pass "curl ftp active mode "
-
-cmp "$INFILE" "$OUTFILE"
-assert_pass "FTP Active mode: in and output files remain the same when FTP traffic passes through NAT."
-
-kill $pid; sync
-tcpdump -nnr ${PCAP} src ${ip_rs} and dst ${ip_sr} 2>&1 |grep -q FTP
-assert_pass "assert FTP traffic NATed"
+test_case "Active mode" [${ip_rc}]:2121 ${ip_rs} "-P -"
 
 # trap calls cleanup
 exit 0
-- 
2.43.0