selftests: seg6: add selftest for PSP flavor in SRv6 End behavior

This selftest is designed for testing the PSP flavor in SRv6 End behavior.
It instantiates a virtual network composed of several nodes: hosts and
SRv6 routers. Each node is realized using a network namespace that is
properly interconnected to others through veth pairs.
The test makes use of the SRv6 End behavior and of the PSP flavor needed
for removing the SRH from the IPv6 header at the penultimate node.

The correct execution of the behavior is verified through reachability
tests carried out between hosts.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Paolo Lungaroni <paolo.lungaroni@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 870 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 3364c548a23b..6cd8993454d7 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -38,6 +38,7 @@ TEST_PROGS += srv6_end_dt6_l3vpn_test.sh
 TEST_PROGS += srv6_hencap_red_l3vpn_test.sh
 TEST_PROGS += srv6_hl2encap_red_l2vpn_test.sh
 TEST_PROGS += srv6_end_next_csid_l3vpn_test.sh
+TEST_PROGS += srv6_end_flavors_test.sh
 TEST_PROGS += vrf_strict_mode_test.sh
 TEST_PROGS += arp_ndisc_evict_nocarrier.sh
 TEST_PROGS += ndisc_unsolicited_na_test.sh
diff --git a/tools/testing/selftests/net/srv6_end_flavors_test.sh b/tools/testing/selftests/net/srv6_end_flavors_test.sh
new file mode 100755
index 000000000000..50563443a4ad
--- /dev/null
+++ b/tools/testing/selftests/net/srv6_end_flavors_test.sh
@@ -0,0 +1,869 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# author: Andrea Mayer <andrea.mayer@uniroma2.it>
+# author: Paolo Lungaroni <paolo.lungaroni@uniroma2.it>
+#
+# This script is designed to test the support for "flavors" in the SRv6 End
+# behavior.
+#
+# Flavors defined in RFC8986 [1] represent additional operations that can modify
+# or extend the existing SRv6 End, End.X and End.T behaviors. For the sake of
+# convenience, we report the list of flavors described in [1] hereafter:
+#   - Penultimate Segment Pop (PSP);
+#   - Ultimate Segment Pop (USP);
+#   - Ultimate Segment Decapsulation (USD).
+#
+# The End, End.X, and End.T behaviors can support these flavors either
+# individually or in combinations.
+# Currently in this selftest we consider only the PSP flavor for the SRv6 End
+# behavior. However, it is possible to extend the script as soon as other
+# flavors will be supported in the kernel.
+#
+# The purpose of the PSP flavor consists in instructing the penultimate node
+# listed in the SRv6 policy to remove (i.e. pop) the outermost SRH from the IPv6
+# header.
+# A PSP enabled SRv6 End behavior instance processes the SRH by:
+#  - decrementing the Segment Left (SL) value from 1 to 0;
+#  - copying the last SID from the SID List into the IPv6 Destination Address
+#    (DA);
+#  - removing the SRH from the extension headers following the IPv6 header.
+#
+# Once the SRH is removed, the IPv6 packet is forwarded to the destination using
+# the IPv6 DA updated during the PSP operation (i.e. the IPv6 DA corresponding
+# to the last SID carried by the removed SRH).
+#
+# Although the PSP flavor can be set for any SRv6 End behavior instance on any
+# SR node, it will be active only on such behaviors bound to a penultimate SID
+# for a given SRv6 policy.
+#                                                SL=2 SL=1 SL=0
+#                                                  |    |    |
+# For example, given the SRv6 policy (SID List := <X,   Y,   Z>):
+#  - a PSP enabled SRv6 End behavior bound to SID Y will apply the PSP operation
+#    as Segment Left (SL) is 1, corresponding to the Penultimate Segment of the
+#    SID List;
+#  - a PSP enabled SRv6 End behavior bound to SID X will *NOT* apply the PSP
+#    operation as the Segment Left is 2. This behavior instance will apply the
+#    "standard" End packet processing, ignoring the configured PSP flavor at
+#    all.
+#
+# [1] RFC8986: https://datatracker.ietf.org/doc/html/rfc8986
+#
+# Network topology
+# ================
+#
+# The network topology used in this selftest is depicted hereafter, composed by
+# two hosts (hs-1, hs-2) and four routers (rt-1, rt-2, rt-3, rt-4).
+# Hosts hs-1 and hs-2 are connected to routers rt-1 and rt-2, respectively,
+# allowing them to communicate with each other.
+# Traffic exchanged between hs-1 and hs-2 can follow different network paths.
+# The network operator, through specific SRv6 Policies can steer traffic to one
+# path rather than another. In this selftest this is implemented as follows:
+#
+#   i) The SRv6 H.Insert behavior applies SRv6 Policies on traffic received by
+#      connected hosts. It pushes the Segment Routing Header (SRH) after the
+#      IPv6 header. The SRH contains the SID List (i.e. SRv6 Policy) needed for
+#      steering traffic across the segments/waypoints specified in that list;
+#
+#  ii) The SRv6 End behavior advances the active SID in the SID List carried by
+#      the SRH;
+#
+# iii) The PSP enabled SRv6 End behavior is used to remove the SRH when such
+#      behavior is configured on a node bound to the Penultimate Segment carried
+#      by the SID List.
+#
+#                cafe::1                      cafe::2
+#              +--------+                   +--------+
+#              |        |                   |        |
+#              |  hs-1  |                   |  hs-2  |
+#              |        |                   |        |
+#              +---+----+                   +--- +---+
+#     cafe::/64    |                             |      cafe::/64
+#                  |                             |
+#              +---+----+                   +----+---+
+#              |        |  fcf0:0:1:2::/64  |        |
+#              |  rt-1  +-------------------+  rt-2  |
+#              |        |                   |        |
+#              +---+----+                   +----+---+
+#                  |      .               .      |
+#                  |  fcf0:0:1:3::/64   .        |
+#                  |          .       .          |
+#                  |            .   .            |
+#  fcf0:0:1:4::/64 |              .              | fcf0:0:2:3::/64
+#                  |            .   .            |
+#                  |          .       .          |
+#                  |  fcf0:0:2:4::/64   .        |
+#                  |      .               .      |
+#              +---+----+                   +----+---+
+#              |        |                   |        |
+#              |  rt-4  +-------------------+  rt-3  |
+#              |        |  fcf0:0:3:4::/64  |        |
+#              +---+----+                   +----+---+
+#
+# Every fcf0:0:x:y::/64 network interconnects the SRv6 routers rt-x with rt-y in
+# the IPv6 operator network.
+#
+#
+# Local SID table
+# ===============
+#
+# Each SRv6 router is configured with a Local SID table in which SIDs are
+# stored. Considering the given SRv6 router rt-x, at least two SIDs are
+# configured in the Local SID table:
+#
+#   Local SID table for SRv6 router rt-x
+#   +---------------------------------------------------------------------+
+#   |fcff:x::e is associated with the SRv6 End behavior                   |
+#   |fcff:x::ef1 is associated with the SRv6 End behavior with PSP flavor |
+#   +---------------------------------------------------------------------+
+#
+# The fcff::/16 prefix is reserved by the operator for the SIDs. Reachability of
+# SIDs is ensured by proper configuration of the IPv6 operator's network and
+# SRv6 routers.
+#
+#
+# SRv6 Policies
+# =============
+#
+# An SRv6 ingress router applies different SRv6 Policies to the traffic received
+# from connected hosts on the basis of the destination addresses.
+# In case of SRv6 H.Insert behavior, the SRv6 Policy enforcement consists of
+# pushing the SRH (carrying a given SID List) after the existing IPv6 header.
+# Note that in the inserting mode, there is no encapsulation at all.
+#
+#   Before applying an SRv6 Policy using the SRv6 H.Insert behavior
+#   +------+---------+
+#   | IPv6 | Payload |
+#   +------+---------+
+#
+#   After applying an SRv6 Policy using the SRv6 H.Insert behavior
+#   +------+-----+---------+
+#   | IPv6 | SRH | Payload |
+#   +------+-----+---------+
+#
+# Traffic from hs-1 to hs-2
+# -------------------------
+#
+# Packets generated from hs-1 and directed towards hs-2 are
+# handled by rt-1 which applies the following SRv6 Policy:
+#
+#   i.a) IPv6 traffic, SID List=fcff:3::e,fcff:4::ef1,fcff:2::ef1,cafe::2
+#
+# Router rt-1 is configured to enforce the Policy (i.a) through the SRv6
+# H.Insert behavior which pushes the SRH after the existing IPv6 header. This
+# Policy steers the traffic from hs-1 across rt-3, rt-4, rt-2 and finally to the
+# destination hs-2.
+#
+# As the packet reaches the router rt-3, the SRv6 End behavior bound to SID
+# fcff:3::e is triggered. The behavior updates the Segment Left (from SL=3 to
+# SL=2) in the SRH, the IPv6 DA with fcff:4::ef1 and forwards the packet to the
+# next router on the path, i.e. rt-4.
+#
+# When router rt-4 receives the packet, the PSP enabled SRv6 End behavior bound
+# to SID fcff:4::ef1 is executed. Since the SL=2, the PSP operation is *NOT*
+# kicked in and the behavior applies the default End processing: the Segment
+# Left is decreased (from SL=2 to SL=1), the IPv6 DA is updated with the SID
+# fcff:2::ef1 and the packet is forwarded to router rt-2.
+#
+# The PSP enabled SRv6 End behavior on rt-2 is associated with SID fcff:2::ef1
+# and is executed as the packet is received. Because SL=1, the behavior applies
+# the PSP processing on the packet as follows: i) SL is decreased, i.e. from
+# SL=1 to SL=0; ii) last SID (cafe::2) is copied into the IPv6 DA; iii) the
+# outermost SRH is removed from the extension headers following the IPv6 header.
+# Once the PSP processing is completed, the packet is forwarded to the host hs-2
+# (destination).
+#
+# Traffic from hs-2 to hs-1
+# -------------------------
+#
+# Packets generated from hs-2 and directed to hs-1 are handled by rt-2 which
+# applies the following SRv6 Policy:
+#
+#   i.b) IPv6 traffic, SID List=fcff:1::ef1,cafe::1
+#
+# Router rt-2 is configured to enforce the Policy (i.b) through the SRv6
+# H.Insert behavior which pushes the SRH after the existing IPv6 header. This
+# Policy steers the traffic from hs-2 across rt-1 and finally to the
+# destination hs-1
+#
+#
+# When the router rt-1 receives the packet, the PSP enabled SRv6 End behavior
+# associated with the SID fcff:1::ef1 is triggered. Since the SL=1,
+# the PSP operation takes place: i) the SL is decremented; ii) the IPv6 DA is
+# set with the last SID; iii) the SRH is removed from the extension headers
+# after the IPv6 header. At this point, the packet with IPv6 DA=cafe::1 is sent
+# to the destination, i.e. hs-1.
+
+# Kselftest framework requirement - SKIP code is 4.
+readonly ksft_skip=4
+
+readonly RDMSUFF="$(mktemp -u XXXXXXXX)"
+readonly DUMMY_DEVNAME="dum0"
+readonly RT2HS_DEVNAME="veth1"
+readonly LOCALSID_TABLE_ID=90
+readonly IPv6_RT_NETWORK=fcf0:0
+readonly IPv6_HS_NETWORK=cafe
+readonly IPv6_TESTS_ADDR=2001:db8::1
+readonly LOCATOR_SERVICE=fcff
+readonly END_FUNC=000e
+readonly END_PSP_FUNC=0ef1
+
+PING_TIMEOUT_SEC=4
+PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no}
+
+# IDs of routers and hosts are initialized during the setup of the testing
+# network
+ROUTERS=''
+HOSTS=''
+
+SETUP_ERR=1
+
+ret=${ksft_skip}
+nsuccess=0
+nfail=0
+
+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
+			[ "$a" = "q" ] && exit 1
+		fi
+	fi
+}
+
+print_log_test_results()
+{
+	printf "\nTests passed: %3d\n" "${nsuccess}"
+	printf "Tests failed: %3d\n"   "${nfail}"
+
+	# when a test fails, the value of 'ret' is set to 1 (error code).
+	# Conversely, when all tests are passed successfully, the 'ret' value
+	# is set to 0 (success code).
+	if [ "${ret}" -ne 1 ]; then
+		ret=0
+	fi
+}
+
+log_section()
+{
+	echo
+	echo "################################################################################"
+	echo "TEST SECTION: $*"
+	echo "################################################################################"
+}
+
+test_command_or_ksft_skip()
+{
+	local cmd="$1"
+
+	if [ ! -x "$(command -v "${cmd}")" ]; then
+		echo "SKIP: Could not run test without \"${cmd}\" tool";
+		exit "${ksft_skip}"
+	fi
+}
+
+get_nodename()
+{
+	local name="$1"
+
+	echo "${name}-${RDMSUFF}"
+}
+
+get_rtname()
+{
+	local rtid="$1"
+
+	get_nodename "rt-${rtid}"
+}
+
+get_hsname()
+{
+	local hsid="$1"
+
+	get_nodename "hs-${hsid}"
+}
+
+__create_namespace()
+{
+	local name="$1"
+
+	ip netns add "${name}"
+}
+
+create_router()
+{
+	local rtid="$1"
+	local nsname
+
+	nsname="$(get_rtname "${rtid}")"
+
+	__create_namespace "${nsname}"
+}
+
+create_host()
+{
+	local hsid="$1"
+	local nsname
+
+	nsname="$(get_hsname "${hsid}")"
+
+	__create_namespace "${nsname}"
+}
+
+cleanup()
+{
+	local nsname
+	local i
+
+	# destroy routers
+	for i in ${ROUTERS}; do
+		nsname="$(get_rtname "${i}")"
+
+		ip netns del "${nsname}" &>/dev/null || true
+	done
+
+	# destroy hosts
+	for i in ${HOSTS}; do
+		nsname="$(get_hsname "${i}")"
+
+		ip netns del "${nsname}" &>/dev/null || true
+	done
+
+	# check whether the setup phase was completed successfully or not. In
+	# case of an error during the setup phase of the testing environment,
+	# the selftest is considered as "skipped".
+	if [ "${SETUP_ERR}" -ne 0 ]; then
+		echo "SKIP: Setting up the testing environment failed"
+		exit "${ksft_skip}"
+	fi
+
+	exit "${ret}"
+}
+
+add_link_rt_pairs()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local neigh
+	local nsname
+	local neigh_nsname
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		neigh_nsname="$(get_rtname "${neigh}")"
+
+		ip link add "veth-rt-${rt}-${neigh}" netns "${nsname}" \
+			type veth peer name "veth-rt-${neigh}-${rt}" \
+			netns "${neigh_nsname}"
+	done
+}
+
+get_network_prefix()
+{
+	local rt="$1"
+	local neigh="$2"
+	local p="${rt}"
+	local q="${neigh}"
+
+	if [ "${p}" -gt "${q}" ]; then
+		p="${q}"; q="${rt}"
+	fi
+
+	echo "${IPv6_RT_NETWORK}:${p}:${q}"
+}
+
+# Given the description of a router <id:op> as an input, the function returns
+# the <id> token which represents the ID of the router.
+# i.e. input: "12:psp"
+#      output: "12"
+__get_srv6_rtcfg_id()
+{
+	local element="$1"
+
+	echo "${element}" | cut -d':' -f1
+}
+
+# Given the description of a router <id:op> as an input, the function returns
+# the <op> token which represents the operation (e.g. End behavior with or
+# withouth flavors) configured for the node.
+
+# Note that when the operation represents an End behavior with a list of
+# flavors, the output is the ordered version of that list.
+# i.e. input: "5:usp,psp,usd"
+#      output: "psp,usd,usp"
+__get_srv6_rtcfg_op()
+{
+	local element="$1"
+
+	# return the lexicographically ordered flavors
+	echo "${element}" | cut -d':' -f2 | sed 's/,/\n/g' | sort | \
+		xargs | sed 's/ /,/g'
+}
+
+# Setup the basic networking for the routers
+setup_rt_networking()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local nsname
+	local net_prefix
+	local devname
+	local neigh
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		devname="veth-rt-${rt}-${neigh}"
+
+		net_prefix="$(get_network_prefix "${rt}" "${neigh}")"
+
+		ip -netns "${nsname}" addr \
+			add "${net_prefix}::${rt}/64" dev "${devname}" nodad
+
+		ip -netns "${nsname}" link set "${devname}" up
+	done
+
+	ip -netns "${nsname}" link set lo up
+
+	ip -netns "${nsname}" link add ${DUMMY_DEVNAME} type dummy
+	ip -netns "${nsname}" link set ${DUMMY_DEVNAME} up
+
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.default.accept_dad=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.all.forwarding=1
+}
+
+# Setup local SIDs for an SRv6 router
+setup_rt_local_sids()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local net_prefix
+	local devname
+	local nsname
+	local neigh
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		devname="veth-rt-${rt}-${neigh}"
+
+		net_prefix="$(get_network_prefix "${rt}" "${neigh}")"
+
+		# set underlay network routes for SIDs reachability
+		ip -netns "${nsname}" -6 route \
+			add "${LOCATOR_SERVICE}:${neigh}::/32" \
+			table "${LOCALSID_TABLE_ID}" \
+			via "${net_prefix}::${neigh}" dev "${devname}"
+	done
+
+	# Local End behavior (note that "dev" is a dummy interface chosen for
+	# the sake of simplicity).
+	ip -netns "${nsname}" -6 route \
+		add "${LOCATOR_SERVICE}:${rt}::${END_FUNC}" \
+		table "${LOCALSID_TABLE_ID}" \
+		encap seg6local action End dev "${DUMMY_DEVNAME}"
+
+
+	# all SIDs start with a common locator. Routes and SRv6 Endpoint
+	# behavior instaces are grouped together in the 'localsid' table.
+	ip -netns "${nsname}" -6 rule \
+		add to "${LOCATOR_SERVICE}::/16" \
+		lookup "${LOCALSID_TABLE_ID}" prio 999
+
+	# set default routes to unreachable
+	ip -netns "${nsname}" -6 route \
+		add unreachable default metric 4278198272 \
+		dev "${DUMMY_DEVNAME}"
+}
+
+# This helper function builds and installs the SID List (i.e. SRv6 Policy)
+# to be applied on incoming packets at the ingress node. Moreover, it
+# configures the SRv6 nodes specified in the SID List to process the traffic
+# according to the operations required by the Policy itself.
+# args:
+#  $1 - destination host (i.e. cafe::x host)
+#  $2 - SRv6 router configured for enforcing the SRv6 Policy
+#  $3 - compact way to represent a list of SRv6 routers with their operations
+#       (i.e. behaviors) that each of them needs to perform. Every <nodeid:op>
+#       element constructs a SID that is associated with the behavior <op> on
+#       the <nodeid> node. The list of such elements forms an SRv6 Policy.
+__setup_rt_policy()
+{
+	local dst="$1"
+	local encap_rt="$2"
+	local policy_rts="$3"
+	local behavior_cfg
+	local in_nsname
+	local rt_nsname
+	local policy=''
+	local function
+	local fullsid
+	local op_type
+	local node
+	local n
+
+	in_nsname="$(get_rtname "${encap_rt}")"
+
+	for n in ${policy_rts}; do
+		node="$(__get_srv6_rtcfg_id "${n}")"
+		op_type="$(__get_srv6_rtcfg_op "${n}")"
+		rt_nsname="$(get_rtname "${node}")"
+
+		case "${op_type}" in
+		"noflv")
+			policy="${policy}${LOCATOR_SERVICE}:${node}::${END_FUNC},"
+			function="${END_FUNC}"
+			behavior_cfg="End"
+			;;
+
+		"psp")
+			policy="${policy}${LOCATOR_SERVICE}:${node}::${END_PSP_FUNC},"
+			function="${END_PSP_FUNC}"
+			behavior_cfg="End flavors psp"
+			;;
+
+		*)
+			break
+			;;
+		esac
+
+		fullsid="${LOCATOR_SERVICE}:${node}::${function}"
+
+		# add SRv6 Endpoint behavior to the selected router
+		if ! ip -netns "${rt_nsname}" -6 route get "${fullsid}" \
+			&>/dev/null; then
+			ip -netns "${rt_nsname}" -6 route \
+				add "${fullsid}" \
+				table "${LOCALSID_TABLE_ID}" \
+				encap seg6local action ${behavior_cfg} \
+				dev "${DUMMY_DEVNAME}"
+		fi
+	done
+
+	# we need to remove the trailing comma to avoid inserting an empty
+	# address (::0) in the SID List.
+	policy="${policy%,}"
+
+	# add SRv6 policy to incoming traffic sent by connected hosts
+	ip -netns "${in_nsname}" -6 route \
+		add "${IPv6_HS_NETWORK}::${dst}" \
+		encap seg6 mode inline segs "${policy}" \
+		dev "${DUMMY_DEVNAME}"
+
+	ip -netns "${in_nsname}" -6 neigh \
+		add proxy "${IPv6_HS_NETWORK}::${dst}" \
+		dev "${RT2HS_DEVNAME}"
+}
+
+# see __setup_rt_policy
+setup_rt_policy_ipv6()
+{
+	__setup_rt_policy "$1" "$2" "$3"
+}
+
+setup_hs()
+{
+	local hs="$1"
+	local rt="$2"
+	local hsname
+	local rtname
+
+	hsname="$(get_hsname "${hs}")"
+	rtname="$(get_rtname "${rt}")"
+
+	ip netns exec "${hsname}" sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec "${hsname}" sysctl -wq net.ipv6.conf.default.accept_dad=0
+
+	ip -netns "${hsname}" link add veth0 type veth \
+		peer name "${RT2HS_DEVNAME}" netns "${rtname}"
+
+	ip -netns "${hsname}" addr \
+		add "${IPv6_HS_NETWORK}::${hs}/64" dev veth0 nodad
+
+	ip -netns "${hsname}" link set veth0 up
+	ip -netns "${hsname}" link set lo up
+
+	ip -netns "${rtname}" addr \
+		add "${IPv6_HS_NETWORK}::254/64" dev "${RT2HS_DEVNAME}" nodad
+
+	ip -netns "${rtname}" link set "${RT2HS_DEVNAME}" up
+
+	ip netns exec "${rtname}" \
+		sysctl -wq net.ipv6.conf."${RT2HS_DEVNAME}".proxy_ndp=1
+}
+
+setup()
+{
+	local i
+
+	# create routers
+	ROUTERS="1 2 3 4"; readonly ROUTERS
+	for i in ${ROUTERS}; do
+		create_router "${i}"
+	done
+
+	# create hosts
+	HOSTS="1 2"; readonly HOSTS
+	for i in ${HOSTS}; do
+		create_host "${i}"
+	done
+
+	# set up the links for connecting routers
+	add_link_rt_pairs 1 "2 3 4"
+	add_link_rt_pairs 2 "3 4"
+	add_link_rt_pairs 3 "4"
+
+	# set up the basic connectivity of routers and routes required for
+	# reachability of SIDs.
+	setup_rt_networking 1 "2 3 4"
+	setup_rt_networking 2 "1 3 4"
+	setup_rt_networking 3 "1 2 4"
+	setup_rt_networking 4 "1 2 3"
+
+	# set up the hosts connected to routers
+	setup_hs 1 1
+	setup_hs 2 2
+
+	# set up default SRv6 Endpoints (i.e. SRv6 End behavior)
+	setup_rt_local_sids 1 "2 3 4"
+	setup_rt_local_sids 2 "1 3 4"
+	setup_rt_local_sids 3 "1 2 4"
+	setup_rt_local_sids 4 "1 2 3"
+
+	# set up SRv6 policies
+	# create a connection between hosts hs-1 and hs-2.
+	# The path between hs-1 and hs-2 traverses SRv6 aware routers.
+	# For each direction two path are chosen:
+	#
+	# Direction hs-1 -> hs-2 (PSP flavor)
+	#  - rt-1 (SRv6 H.Insert policy)
+	#  - rt-3 (SRv6 End behavior)
+	#  - rt-4 (SRv6 End flavor PSP with SL>1, acting as End behavior)
+	#  - rt-2 (SRv6 End flavor PSP with SL=1)
+	#
+	# Direction hs-2 -> hs-1 (PSP flavor)
+	#  - rt-2 (SRv6 H.Insert policy)
+	#  - rt-1 (SRv6 End flavor PSP with SL=1)
+	setup_rt_policy_ipv6 2 1 "3:noflv 4:psp 2:psp"
+	setup_rt_policy_ipv6 1 2 "1:psp"
+
+	# testing environment was set up successfully
+	SETUP_ERR=0
+}
+
+check_rt_connectivity()
+{
+	local rtsrc="$1"
+	local rtdst="$2"
+	local prefix
+	local rtsrc_nsname
+
+	rtsrc_nsname="$(get_rtname "${rtsrc}")"
+
+	prefix="$(get_network_prefix "${rtsrc}" "${rtdst}")"
+
+	ip netns exec "${rtsrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${prefix}::${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_ipv6_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+	local hssrc_nsname
+
+	hssrc_nsname="$(get_hsname "${hssrc}")"
+
+	ip netns exec "${hssrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${IPv6_HS_NETWORK}::${hsdst}" >/dev/null 2>&1
+}
+
+check_and_log_hs2gw_connectivity()
+{
+	local hssrc="$1"
+
+	check_hs_ipv6_connectivity "${hssrc}" 254
+	log_test $? 0 "IPv6 Hosts connectivity: hs-${hssrc} -> gw"
+}
+
+check_and_log_hs_ipv6_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 0 "IPv6 Hosts connectivity: hs-${hssrc} -> hs-${hsdst}"
+}
+
+check_and_log_hs_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_and_log_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+}
+
+router_tests()
+{
+	local i
+	local j
+
+	log_section "IPv6 routers connectivity test"
+
+	for i in ${ROUTERS}; do
+		for j in ${ROUTERS}; do
+			if [ "${i}" -eq "${j}" ]; then
+				continue
+			fi
+
+			check_and_log_rt_connectivity "${i}" "${j}"
+		done
+	done
+}
+
+host2gateway_tests()
+{
+	local hs
+
+	log_section "IPv6 connectivity test among hosts and gateways"
+
+	for hs in ${HOSTS}; do
+		check_and_log_hs2gw_connectivity "${hs}"
+	done
+}
+
+host_srv6_end_flv_psp_tests()
+{
+	log_section "SRv6 connectivity test hosts (h1 <-> h2, PSP flavor)"
+
+	check_and_log_hs_connectivity 1 2
+	check_and_log_hs_connectivity 2 1
+}
+
+test_iproute2_supp_or_ksft_skip()
+{
+	local flavor="$1"
+
+	if ! ip route help 2>&1 | grep -qo "${flavor}"; then
+		echo "SKIP: Missing SRv6 ${flavor} flavor support in iproute2"
+		exit "${ksft_skip}"
+	fi
+}
+
+test_kernel_supp_or_ksft_skip()
+{
+	local flavor="$1"
+	local test_netns
+
+	test_netns="kflv-$(mktemp -u XXXXXXXX)"
+
+	if ! ip netns add "${test_netns}"; then
+		echo "SKIP: Cannot set up netns to test kernel support for flavors"
+		exit "${ksft_skip}"
+	fi
+
+	if ! ip -netns "${test_netns}" link \
+		add "${DUMMY_DEVNAME}" type dummy; then
+		echo "SKIP: Cannot set up dummy dev to test kernel support for flavors"
+
+		ip netns del "${test_netns}"
+		exit "${ksft_skip}"
+	fi
+
+	if ! ip -netns "${test_netns}" link \
+		set "${DUMMY_DEVNAME}" up; then
+		echo "SKIP: Cannot activate dummy dev to test kernel support for flavors"
+
+		ip netns del "${test_netns}"
+		exit "${ksft_skip}"
+	fi
+
+	if ! ip -netns "${test_netns}" -6 route \
+		add "${IPv6_TESTS_ADDR}" encap seg6local \
+		action End flavors "${flavor}" dev "${DUMMY_DEVNAME}"; then
+		echo "SKIP: ${flavor} flavor not supported in kernel"
+
+		ip netns del "${test_netns}"
+		exit "${ksft_skip}"
+	fi
+
+	ip netns del "${test_netns}"
+}
+
+test_dummy_dev_or_ksft_skip()
+{
+	local test_netns
+
+	test_netns="dummy-$(mktemp -u XXXXXXXX)"
+
+	if ! ip netns add "${test_netns}"; then
+		echo "SKIP: Cannot set up netns for testing dummy dev support"
+		exit "${ksft_skip}"
+	fi
+
+	modprobe dummy &>/dev/null || true
+	if ! ip -netns "${test_netns}" link \
+		add "${DUMMY_DEVNAME}" type dummy; then
+		echo "SKIP: dummy dev not supported"
+
+		ip netns del "${test_netns}"
+		exit "${ksft_skip}"
+	fi
+
+	ip netns del "${test_netns}"
+}
+
+if [ "$(id -u)" -ne 0 ]; then
+	echo "SKIP: Need root privileges"
+	exit "${ksft_skip}"
+fi
+
+# required programs to carry out this selftest
+test_command_or_ksft_skip ip
+test_command_or_ksft_skip ping
+test_command_or_ksft_skip sysctl
+test_command_or_ksft_skip grep
+test_command_or_ksft_skip cut
+test_command_or_ksft_skip sed
+test_command_or_ksft_skip sort
+test_command_or_ksft_skip xargs
+
+test_dummy_dev_or_ksft_skip
+test_iproute2_supp_or_ksft_skip psp
+test_kernel_supp_or_ksft_skip psp
+
+set -e
+trap cleanup EXIT
+
+setup
+set +e
+
+router_tests
+host2gateway_tests
+host_srv6_end_flv_psp_tests
+
+print_log_test_results