pf tests: dummynet + nat fragmentation test

Ensure that we do the right thing when we reassemble fragmented packet
and send it through a dummynet pipe.

Sponsored by:	Rubicon Communications, LLC ("Netgate")

tests/sys/netpfil/pf/fragmentation_pass.sh

@@ -506,6 +506,53 @@ dummynet_cleanup()
 	pft_cleanup
 }
 
+atf_test_case "dummynet_nat" "cleanup"
+dummynet_nat_head()
+{
+	atf_set descr 'Test dummynet on NATed fragmented traffic'
+	atf_set require.user root
+}
+
+dummynet_nat_body()
+{
+	pft_init
+	dummynet_init
+
+	epair_one=$(vnet_mkepair)
+	ifconfig ${epair_one}a 192.0.2.1/24 up
+
+	epair_two=$(vnet_mkepair)
+
+	vnet_mkjail alcatraz ${epair_one}b ${epair_two}a
+	jexec alcatraz ifconfig ${epair_one}b 192.0.2.2/24 up
+	jexec alcatraz ifconfig ${epair_two}a 198.51.100.1/24 up
+	jexec alcatraz sysctl net.inet.ip.forwarding=1
+
+	vnet_mkjail singsing ${epair_two}b
+	jexec singsing ifconfig ${epair_two}b 198.51.100.2/24 up
+	jexec singsing route add default 198.51.100.1
+
+	route add 198.51.100.0/24 192.0.2.2
+
+	jexec alcatraz dnctl pipe 1 config bw 1600Byte/s
+	jexec alcatraz dnctl pipe 2 config bw 1700Byte/s
+
+	jexec alcatraz pfctl -e
+	pft_set_rules alcatraz \
+		"set reassemble yes" \
+		"nat on ${epair_two}a from 192.0.2.0/24 -> (${epair_two}a)" \
+		"block in" \
+		"pass in inet proto icmp all icmp-type echoreq dnpipe (1, 2)"
+
+	atf_check -s exit:0 -o ignore ping -c 1 198.51.100.2
+	atf_check -s exit:0 -o ignore ping -c 1 -s 2000 198.51.100.2
+}
+
+dummynet_nat_cleanup()
+{
+	pft_cleanup
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case "too_many_fragments"
@@ -518,4 +565,5 @@ atf_init_test_cases()
 	atf_add_test_case "no_df"
 	atf_add_test_case "reassemble_slowpath"
 	atf_add_test_case "dummynet"
+	atf_add_test_case "dummynet_nat"
 }