#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
#
# author: Andrea Mayer <andrea.mayer@uniroma2.it>

# This test is designed for evaluating the new SRv6 End.DT4 behavior used for
# implementing IPv4 L3 VPN use cases.
#
# Hereafter a network diagram is shown, where two different tenants (named 100
# and 200) offer IPv4 L3 VPN services allowing hosts to communicate with each
# other across an IPv6 network.
#
# Only hosts belonging to the same tenant (and to the same VPN) can communicate
# with each other. Instead, the communication among hosts of different tenants
# is forbidden.
# In other words, hosts hs-t100-1 and hs-t100-2 are connected through the IPv4
# L3 VPN of tenant 100 while hs-t200-3 and hs-t200-4 are connected using the
# IPv4 L3 VPN of tenant 200. Cross connection between tenant 100 and tenant 200
# is forbidden and thus, for example, hs-t100-1 cannot reach hs-t200-3 and vice
# versa.
#
# Routers rt-1 and rt-2 implement IPv4 L3 VPN services leveraging the SRv6
# architecture. The key components for such VPNs are: a) SRv6 Encap behavior,
# b) SRv6 End.DT4 behavior and c) VRF.
#
# To explain how an IPv4 L3 VPN based on SRv6 works, let us briefly consider an
# example where, within the same domain of tenant 100, the host hs-t100-1 pings
# the host hs-t100-2.
#
# First of all, L2 reachability of the host hs-t100-2 is taken into account by
# the router rt-1 which acts as an arp proxy.
#
# When the host hs-t100-1 sends an IPv4 packet destined to hs-t100-2, the
# router rt-1 receives the packet on the internal veth-t100 interface. Such
# interface is enslaved to the VRF vrf-100 whose associated table contains the
# SRv6 Encap route for encapsulating any IPv4 packet in a IPv6 plus the Segment
# Routing Header (SRH) packet. This packet is sent through the (IPv6) core
# network up to the router rt-2 that receives it on veth0 interface.
#
# The rt-2 router uses the 'localsid' routing table to process incoming
# IPv6+SRH packets which belong to the VPN of the tenant 100. For each of these
# packets, the SRv6 End.DT4 behavior removes the outer IPv6+SRH headers and
# performs the lookup on the vrf-100 table using the destination address of
# the decapsulated IPv4 packet. Afterwards, the packet is sent to the host
# hs-t100-2 through the veth-t100 interface.
#
# The ping response follows the same processing but this time the role of rt-1
# and rt-2 are swapped.
#
# Of course, the IPv4 L3 VPN for tenant 200 works exactly as the IPv4 L3 VPN
# for tenant 100. In this case, only hosts hs-t200-3 and hs-t200-4 are able to
# connect with each other.
#
#
# +-------------------+                                   +-------------------+
# |                   |                                   |                   |
# |  hs-t100-1 netns  |                                   |  hs-t100-2 netns  |
# |                   |                                   |                   |
# |  +-------------+  |                                   |  +-------------+  |
# |  |    veth0    |  |                                   |  |    veth0    |  |
# |  | 10.0.0.1/24 |  |                                   |  | 10.0.0.2/24 |  |
# |  +-------------+  |                                   |  +-------------+  |
# |        .          |                                   |         .         |
# +-------------------+                                   +-------------------+
#          .                                                        .
#          .                                                        .
#          .                                                        .
# +-----------------------------------+   +-----------------------------------+
# |        .                          |   |                         .         |
# | +---------------+                 |   |                 +---------------- |
# | |   veth-t100   |                 |   |                 |   veth-t100   | |
# | | 10.0.0.254/24 |    +----------+ |   | +----------+    | 10.0.0.254/24 | |
# | +-------+-------+    | localsid | |   | | localsid |    +-------+-------- |
# |         |            |   table  | |   | |   table  |            |         |
# |    +----+----+       +----------+ |   | +----------+       +----+----+    |
# |    | vrf-100 |                    |   |                    | vrf-100 |    |
# |    +---------+     +------------+ |   | +------------+     +---------+    |
# |                    |   veth0    | |   | |   veth0    |                    |
# |                    | fd00::1/64 |.|...|.| fd00::2/64 |                    |
# |    +---------+     +------------+ |   | +------------+     +---------+    |
# |    | vrf-200 |                    |   |                    | vrf-200 |    |
# |    +----+----+                    |   |                    +----+----+    |
# |         |                         |   |                         |         |
# | +-------+-------+                 |   |                 +-------+-------- |
# | |   veth-t200   |                 |   |                 |   veth-t200   | |
# | | 10.0.0.254/24 |                 |   |                 | 10.0.0.254/24 | |
# | +---------------+      rt-1 netns |   | rt-2 netns      +---------------- |
# |        .                          |   |                          .        |
# +-----------------------------------+   +-----------------------------------+
#          .                                                         .
#          .                                                         .
#          .                                                         .
#          .                                                         .
# +-------------------+                                   +-------------------+
# |        .          |                                   |          .        |
# |  +-------------+  |                                   |  +-------------+  |
# |  |    veth0    |  |                                   |  |    veth0    |  |
# |  | 10.0.0.3/24 |  |                                   |  | 10.0.0.4/24 |  |
# |  +-------------+  |                                   |  +-------------+  |
# |                   |                                   |                   |
# |  hs-t200-3 netns  |                                   |  hs-t200-4 netns  |
# |                   |                                   |                   |
# +-------------------+                                   +-------------------+
#
#
# ~~~~~~~~~~~~~~~~~~~~~~~~~
# | Network configuration |
# ~~~~~~~~~~~~~~~~~~~~~~~~~
#
# rt-1: localsid table (table 90)
# +-------------------------------------------------+
# |SID              |Action                         |
# +-------------------------------------------------+
# |fc00:21:100::6004|apply SRv6 End.DT4 vrftable 100|
# +-------------------------------------------------+
# |fc00:21:200::6004|apply SRv6 End.DT4 vrftable 200|
# +-------------------------------------------------+
#
# rt-1: VRF tenant 100 (table 100)
# +---------------------------------------------------+
# |host       |Action                                 |
# +---------------------------------------------------+
# |10.0.0.2   |apply seg6 encap segs fc00:12:100::6004|
# +---------------------------------------------------+
# |10.0.0.0/24|forward to dev veth_t100               |
# +---------------------------------------------------+
#
# rt-1: VRF tenant 200 (table 200)
# +---------------------------------------------------+
# |host       |Action                                 |
# +---------------------------------------------------+
# |10.0.0.4   |apply seg6 encap segs fc00:12:200::6004|
# +---------------------------------------------------+
# |10.0.0.0/24|forward to dev veth_t200               |
# +---------------------------------------------------+
#
#
# rt-2: localsid table (table 90)
# +-------------------------------------------------+
# |SID              |Action                         |
# +-------------------------------------------------+
# |fc00:12:100::6004|apply SRv6 End.DT4 vrftable 100|
# +-------------------------------------------------+
# |fc00:12:200::6004|apply SRv6 End.DT4 vrftable 200|
# +-------------------------------------------------+
#
# rt-2: VRF tenant 100 (table 100)
# +---------------------------------------------------+
# |host       |Action                                 |
# +---------------------------------------------------+
# |10.0.0.1   |apply seg6 encap segs fc00:21:100::6004|
# +---------------------------------------------------+
# |10.0.0.0/24|forward to dev veth_t100               |
# +---------------------------------------------------+
#
# rt-2: VRF tenant 200 (table 200)
# +---------------------------------------------------+
# |host       |Action                                 |
# +---------------------------------------------------+
# |10.0.0.3   |apply seg6 encap segs fc00:21:200::6004|
# +---------------------------------------------------+
# |10.0.0.0/24|forward to dev veth_t200               |
# +---------------------------------------------------+
#

readonly LOCALSID_TABLE_ID=90
readonly IPv6_RT_NETWORK=fd00
readonly IPv4_HS_NETWORK=10.0.0
readonly VPN_LOCATOR_SERVICE=fc00
PING_TIMEOUT_SEC=4

ret=0

PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no}

log_test()
{
	local rc=$1
	local expected=$2
	local msg="$3"

	if [ ${rc} -eq ${expected} ]; then
		nsuccess=$((nsuccess+1))
		printf "\n    TEST: %-60s  [ OK ]\n" "${msg}"
	else
		ret=1
		nfail=$((nfail+1))
		printf "\n    TEST: %-60s  [FAIL]\n" "${msg}"
		if [ "${PAUSE_ON_FAIL}" = "yes" ]; then
			echo
			echo "hit enter to continue, 'q' to quit"
			read a
			[ "$a" = "q" ] && exit 1
		fi
	fi
}

print_log_test_results()
{
	if [ "$TESTS" != "none" ]; then
		printf "\nTests passed: %3d\n" ${nsuccess}
		printf "Tests failed: %3d\n"   ${nfail}
	fi
}

log_section()
{
	echo
	echo "################################################################################"
	echo "TEST SECTION: $*"
	echo "################################################################################"
}

cleanup()
{
	ip link del veth-rt-1 2>/dev/null || true
	ip link del veth-rt-2 2>/dev/null || true

	# destroy routers rt-* and hosts hs-*
	for ns in $(ip netns show | grep -E 'rt-*|hs-*'); do
		ip netns del ${ns} || true
	done
}

# Setup the basic networking for the routers
setup_rt_networking()
{
	local rt=$1
	local nsname=rt-${rt}

	ip netns add ${nsname}
	ip link set veth-rt-${rt} netns ${nsname}
	ip -netns ${nsname} link set veth-rt-${rt} name veth0

	ip -netns ${nsname} addr add ${IPv6_RT_NETWORK}::${rt}/64 dev veth0
	ip -netns ${nsname} link set veth0 up
	ip -netns ${nsname} link set lo up

	ip netns exec ${nsname} sysctl -wq net.ipv4.ip_forward=1
	ip netns exec ${nsname} sysctl -wq net.ipv6.conf.all.forwarding=1
}

setup_hs()
{
	local hs=$1
	local rt=$2
	local tid=$3
	local hsname=hs-t${tid}-${hs}
	local rtname=rt-${rt}
	local rtveth=veth-t${tid}

	# set the networking for the host
	ip netns add ${hsname}
	ip -netns ${hsname} link add veth0 type veth peer name ${rtveth}
	ip -netns ${hsname} link set ${rtveth} netns ${rtname}
	ip -netns ${hsname} addr add ${IPv4_HS_NETWORK}.${hs}/24 dev veth0
	ip -netns ${hsname} link set veth0 up
	ip -netns ${hsname} link set lo up

	# configure the VRF for the tenant X on the router which is directly
	# connected to the source host.
	ip -netns ${rtname} link add vrf-${tid} type vrf table ${tid}
	ip -netns ${rtname} link set vrf-${tid} up

	# enslave the veth-tX interface to the vrf-X in the access router
	ip -netns ${rtname} link set ${rtveth} master vrf-${tid}
	ip -netns ${rtname} addr add ${IPv4_HS_NETWORK}.254/24 dev ${rtveth}
	ip -netns ${rtname} link set ${rtveth} up

	ip netns exec ${rtname} sysctl -wq net.ipv4.conf.${rtveth}.proxy_arp=1

	# disable the rp_filter otherwise the kernel gets confused about how
	# to route decap ipv4 packets.
	ip netns exec ${rtname} sysctl -wq net.ipv4.conf.all.rp_filter=0
	ip netns exec ${rtname} sysctl -wq net.ipv4.conf.${rtveth}.rp_filter=0

	ip netns exec ${rtname} sh -c "echo 1 > /proc/sys/net/vrf/strict_mode"
}

setup_vpn_config()
{
	local hssrc=$1
	local rtsrc=$2
	local hsdst=$3
	local rtdst=$4
	local tid=$5

	local hssrc_name=hs-t${tid}-${hssrc}
	local hsdst_name=hs-t${tid}-${hsdst}
	local rtsrc_name=rt-${rtsrc}
	local rtdst_name=rt-${rtdst}
	local vpn_sid=${VPN_LOCATOR_SERVICE}:${hssrc}${hsdst}:${tid}::6004

	# set the encap route for encapsulating packets which arrive from the
	# host hssrc and destined to the access router rtsrc.
	ip -netns ${rtsrc_name} -4 route add ${IPv4_HS_NETWORK}.${hsdst}/32 vrf vrf-${tid} \
		encap seg6 mode encap segs ${vpn_sid} dev veth0
	ip -netns ${rtsrc_name} -6 route add ${vpn_sid}/128 vrf vrf-${tid} \
		via fd00::${rtdst} dev veth0

	# set the decap route for decapsulating packets which arrive from
	# the rtdst router and destined to the hsdst host.
	ip -netns ${rtdst_name} -6 route add ${vpn_sid}/128 table ${LOCALSID_TABLE_ID} \
		encap seg6local action End.DT4 vrftable ${tid} dev vrf-${tid}

	# all sids for VPNs start with a common locator which is fc00::/16.
	# Routes for handling the SRv6 End.DT4 behavior instances are grouped
	# together in the 'localsid' table.
	#
	# NOTE: added only once
	if [ -z "$(ip -netns ${rtdst_name} -6 rule show | \
	    grep "to ${VPN_LOCATOR_SERVICE}::/16 lookup ${LOCALSID_TABLE_ID}")" ]; then
		ip -netns ${rtdst_name} -6 rule add \
			to ${VPN_LOCATOR_SERVICE}::/16 \
			lookup ${LOCALSID_TABLE_ID} prio 999
	fi
}

setup()
{
	ip link add veth-rt-1 type veth peer name veth-rt-2
	# setup the networking for router rt-1 and router rt-2
	setup_rt_networking 1
	setup_rt_networking 2

	# setup two hosts for the tenant 100.
	#  - host hs-1 is directly connected to the router rt-1;
	#  - host hs-2 is directly connected to the router rt-2.
	setup_hs 1 1 100  #args: host router tenant
	setup_hs 2 2 100

	# setup two hosts for the tenant 200
	#  - host hs-3 is directly connected to the router rt-1;
	#  - host hs-4 is directly connected to the router rt-2.
	setup_hs 3 1 200
	setup_hs 4 2 200

	# setup the IPv4 L3 VPN which connects the host hs-t100-1 and host
	# hs-t100-2 within the same tenant 100.
	setup_vpn_config 1 1 2 2 100  #args: src_host src_router dst_host dst_router tenant
	setup_vpn_config 2 2 1 1 100

	# setup the IPv4 L3 VPN which connects the host hs-t200-3 and host
	# hs-t200-4 within the same tenant 200.
	setup_vpn_config 3 1 4 2 200
	setup_vpn_config 4 2 3 1 200
}

check_rt_connectivity()
{
	local rtsrc=$1
	local rtdst=$2

	ip netns exec rt-${rtsrc} ping -c 1 -W 1 ${IPv6_RT_NETWORK}::${rtdst} \
		>/dev/null 2>&1
}

check_and_log_rt_connectivity()
{
	local rtsrc=$1
	local rtdst=$2

	check_rt_connectivity ${rtsrc} ${rtdst}
	log_test $? 0 "Routers connectivity: rt-${rtsrc} -> rt-${rtdst}"
}

check_hs_connectivity()
{
	local hssrc=$1
	local hsdst=$2
	local tid=$3

	ip netns exec hs-t${tid}-${hssrc} ping -c 1 -W ${PING_TIMEOUT_SEC} \
		${IPv4_HS_NETWORK}.${hsdst} >/dev/null 2>&1
}

check_and_log_hs_connectivity()
{
	local hssrc=$1
	local hsdst=$2
	local tid=$3

	check_hs_connectivity ${hssrc} ${hsdst} ${tid}
	log_test $? 0 "Hosts connectivity: hs-t${tid}-${hssrc} -> hs-t${tid}-${hsdst} (tenant ${tid})"
}

check_and_log_hs_isolation()
{
	local hssrc=$1
	local tidsrc=$2
	local hsdst=$3
	local tiddst=$4

	check_hs_connectivity ${hssrc} ${hsdst} ${tidsrc}
	# NOTE: ping should fail
	log_test $? 1 "Hosts isolation: hs-t${tidsrc}-${hssrc} -X-> hs-t${tiddst}-${hsdst}"
}


check_and_log_hs2gw_connectivity()
{
	local hssrc=$1
	local tid=$2

	check_hs_connectivity ${hssrc} 254 ${tid}
	log_test $? 0 "Hosts connectivity: hs-t${tid}-${hssrc} -> gw (tenant ${tid})"
}

router_tests()
{
	log_section "IPv6 routers connectivity test"

	check_and_log_rt_connectivity 1 2
	check_and_log_rt_connectivity 2 1
}

host2gateway_tests()
{
	log_section "IPv4 connectivity test among hosts and gateway"

	check_and_log_hs2gw_connectivity 1 100
	check_and_log_hs2gw_connectivity 2 100

	check_and_log_hs2gw_connectivity 3 200
	check_and_log_hs2gw_connectivity 4 200
}

host_vpn_tests()
{
	log_section "SRv6 VPN connectivity test among hosts in the same tenant"

	check_and_log_hs_connectivity 1 2 100
	check_and_log_hs_connectivity 2 1 100

	check_and_log_hs_connectivity 3 4 200
	check_and_log_hs_connectivity 4 3 200
}

host_vpn_isolation_tests()
{
	local i
	local j
	local k
	local tmp
	local l1="1 2"
	local l2="3 4"
	local t1=100
	local t2=200

	log_section "SRv6 VPN isolation test among hosts in different tentants"

	for k in 0 1; do
		for i in ${l1}; do
			for j in ${l2}; do
				check_and_log_hs_isolation ${i} ${t1} ${j} ${t2}
			done
		done

		# let us test the reverse path
		tmp="${l1}"; l1="${l2}"; l2="${tmp}"
		tmp=${t1}; t1=${t2}; t2=${tmp}
	done
}

if [ "$(id -u)" -ne 0 ];then
	echo "SKIP: Need root privileges"
	exit 0
fi

if [ ! -x "$(command -v ip)" ]; then
	echo "SKIP: Could not run test without ip tool"
	exit 0
fi

modprobe vrf &>/dev/null
if [ ! -e /proc/sys/net/vrf/strict_mode ]; then
        echo "SKIP: vrf sysctl does not exist"
        exit 0
fi

cleanup &>/dev/null

setup

router_tests
host2gateway_tests
host_vpn_tests
host_vpn_isolation_tests

print_log_test_results

cleanup &>/dev/null

exit ${ret}