#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
#
# author: Jianguo Wu <wujianguo@chinatelecom.cn>
#
# Mostly copied from tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh.
#
# This script is designed for testing the support of netfilter hooks for
# SRv6 End.DX4 behavior.
#
# Hereafter a network diagram is shown, where one tenants (named 100) offer
# IPv4 L3 VPN services allowing hosts to communicate with each other across
# an IPv6 network.
#
# 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.DX4 behavior.
#
# 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-1 pings
# the host hs-2.
#
# First of all, L2 reachability of the host hs-2 is taken into account by
# the router rt-1 which acts as an arp proxy.
#
# When the host hs-1 sends an IPv4 packet destined to hs-2, the router rt-1
# receives the packet on the internal veth-t100 interface, rt-1 contains the
# SRv6 Encap route for encapsulating the 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.DX4 behavior removes the outer IPv6+SRH headers and
# routs the packet to the specified nexthop. Afterwards, the packet is sent to
# the host hs-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.
#
# And when net.netfilter.nf_hooks_lwtunnel is set to 1 in rt-1 or rt-2, and a
# rpfilter iptables rule is added, SRv6 packets will go through netfilter PREROUTING
# hooks.
#
#
# +-------------------+                                   +-------------------+
# |                   |                                   |                   |
# |    hs-1 netns     |                                   |     hs-2 netns    |
# |                   |                                   |                   |
# |  +-------------+  |                                   |  +-------------+  |
# |  |    veth0    |  |                                   |  |    veth0    |  |
# |  | 10.0.0.1/24 |  |                                   |  | 10.0.0.2/24 |  |
# |  +-------------+  |                                   |  +-------------+  |
# |        .          |                                   |         .         |
# +-------------------+                                   +-------------------+
#          .                                                        .
#          .                                                        .
#          .                                                        .
# +-----------------------------------+   +-----------------------------------+
# |        .                          |   |                         .         |
# | +---------------+                 |   |                 +---------------- |
# | |   veth-t100   |                 |   |                 |   veth-t100   | |
# | | 10.0.0.11/24  |    +----------+ |   | +----------+    | 10.0.0.22/24  | |
# | +-------+-------+   |   route   | |   | |   route  |    +-------+-------- |
# |                     |   table   | |   | |   table  |                      |
# |                      +----------+ |   | +----------+                      |
# |                  +--------------+ |   | +--------------+                  |
# |                 |      veth0    | |   | |   veth0       |                 |
# |                 | 2001:11::1/64 |.|...|.| 2001:11::2/64 |                 |
# |                  +--------------+ |   | +--------------+                  |
# |                                   |   |                                   |
# |                        rt-1 netns |   | rt-2 netns                        |
# |                                   |   |                                   |
# +-----------------------------------+   +-----------------------------------+
#
# ~~~~~~~~~~~~~~~~~~~~~~~~~
# | Network configuration |
# ~~~~~~~~~~~~~~~~~~~~~~~~~
#
# rt-1: localsid table
# +----------------------------------------------------------------+
# |SID              |Action                                        |
# +----------------------------------------------------------------+
# |fc00:21:100::6004|apply SRv6 End.DX4 nh4 10.0.0.1 dev veth-t100 |
# +----------------------------------------------------------------+
#
# rt-1: route table
# +---------------------------------------------------+
# |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-2: localsid table
# +---------------------------------------------------------------+
# |SID              |Action                                       |
# +---------------------------------------------------------------+
# |fc00:12:100::6004|apply SRv6 End.DX4 nh4 10.0.0.2 dev veth-t100|
# +---------------------------------------------------------------+
#
# rt-2: route table
# +---------------------------------------------------+
# |host       |Action                                 |
# +---------------------------------------------------+
# |10.0.0.1   |apply seg6 encap segs fc00:21:100::6004|
# +---------------------------------------------------+
# |10.0.0.0/24|forward to dev veth_t100               |
# +---------------------------------------------------+
#

# Kselftest framework requirement - SKIP code is 4.
ksft_skip=4

readonly IPv6_RT_NETWORK=2001:11
readonly IPv4_HS_NETWORK=10.0.0
readonly SID_LOCATOR=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 netns exec ${nsname} sysctl -wq net.ipv6.conf.all.accept_dad=0
	ip netns exec ${nsname} sysctl -wq net.ipv6.conf.default.accept_dad=0

	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 nodad
	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_rt_netfilter()
{
	local rt=$1
	local nsname=rt-${rt}

	ip netns exec ${nsname} sysctl -wq net.netfilter.nf_hooks_lwtunnel=1
	ip netns exec ${nsname} iptables -t raw -A PREROUTING -m rpfilter --invert -j DROP
}

setup_hs()
{
	local hs=$1
	local rt=$2
	local tid=$3
	local hsname=hs-${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

	ip -netns ${rtname} addr add ${IPv4_HS_NETWORK}.${rt}${hs}/24 dev ${rtveth}
	ip -netns ${rtname} link set ${rtveth} up

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

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=${SID_LOCATOR}:${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 \
		encap seg6 mode encap segs ${vpn_sid} dev veth0
	ip -netns ${rtsrc_name} -6 route add ${vpn_sid}/128 \
		via 2001:11::${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 \
		encap seg6local action End.DX4 nh4 ${IPv4_HS_NETWORK}.${hsdst} dev veth-t${tid}
}

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
	setup_hs 2 2 100

	# setup the IPv4 L3 VPN which connects the host hs-1 and host hs-2.
	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
}

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

	ip netns exec hs-${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 $? 0 "Hosts connectivity: hs-${hssrc} -> hs-${hsdst} (tenant ${tid})"
}

host_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
}

router_netfilter_tests()
{
	log_section "SRv6 VPN connectivity test with netfilter enabled in routers"
	setup_rt_netfilter 1
	setup_rt_netfilter 2

	check_and_log_hs_connectivity 1 2 100
	check_and_log_hs_connectivity 2 1 100
}

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

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

cleanup &>/dev/null

setup

host_tests
router_netfilter_tests

print_log_test_results

cleanup &>/dev/null

exit ${ret}