[PATCH net-next 4/4] selftests: net: hsr: add PRP RedBox test

[Xin Xie <xiexinet@gmail.com>]

Add a kselftest that builds a PRP RedBox (interlink) with a SAN behind the
interlink and a peer DANP, and checks bidirectional unicast across the
interlink, preservation of the SAN source MAC on the PRP network, and that
the proxy-announce supervision frame carries the RedBox-MAC TLV (Type 30)
terminated by an EOT marker. It reuses the hsr_common.sh / lib.sh helpers
and skips cleanly on a kernel or iproute2 without PRP interlink support.

Signed-off-by: Xin Xie <xiexinet@gmail.com>
---
 tools/testing/selftests/net/hsr/Makefile      |  1 +
 .../selftests/net/hsr/hsr_prp_redbox.sh       | 96 +++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100755 tools/testing/selftests/net/hsr/hsr_prp_redbox.sh

diff --git a/tools/testing/selftests/net/hsr/Makefile b/tools/testing/selftests/net/hsr/Makefile
index 31fb9326c..2150e487a 100644
--- a/tools/testing/selftests/net/hsr/Makefile
+++ b/tools/testing/selftests/net/hsr/Makefile
@@ -4,6 +4,7 @@ top_srcdir = ../../../../..
 
 TEST_PROGS := \
 	hsr_ping.sh \
+	hsr_prp_redbox.sh \
 	hsr_redbox.sh \
 	link_faults.sh \
 	prp_ping.sh \
diff --git a/tools/testing/selftests/net/hsr/hsr_prp_redbox.sh b/tools/testing/selftests/net/hsr/hsr_prp_redbox.sh
new file mode 100755
index 000000000..8ae36737b
--- /dev/null
+++ b/tools/testing/selftests/net/hsr/hsr_prp_redbox.sh
@@ -0,0 +1,96 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Test a PRP RedBox (PRP-SAN): a SAN that sits behind the interlink port must
+# reach, and be reached by, a peer DANP on the PRP network with its own MAC
+# preserved on the wire, and the RedBox must announce the SAN with a RedBox-MAC
+# TLV (terminated by an EOT marker) in its PRP supervision frames.
+#
+#   RB    PRP RedBox: prp0 over rb_a/rb_b (LAN A/B) + interlink rb_il
+#   PEER  peer DANP : prp0 over pe_a/pe_b, 100.64.0.2
+#   SAN   SAN       : san_il, own MAC, 100.64.0.51 (behind the interlink)
+
+ipv6=false
+
+source ./hsr_common.sh
+
+check_prerequisites
+
+if ! command -v tcpdump >/dev/null 2>&1; then
+	echo "SKIP: This test requires tcpdump"
+	exit $ksft_skip
+fi
+
+if ! ip link help hsr 2>&1 | grep -q interlink; then
+	echo "SKIP: iproute2 too old (no hsr interlink support)"
+	exit $ksft_skip
+fi
+
+setup_ns RB PEER SAN
+trap 'cleanup_ns "$RB" "$PEER" "$SAN"' EXIT
+
+ip link add rb_a netns "$RB" type veth peer name pe_a netns "$PEER"
+ip link add rb_b netns "$RB" type veth peer name pe_b netns "$PEER"
+ip link add rb_il netns "$RB" type veth peer name san_il netns "$SAN"
+
+ip -n "$RB"   link set rb_a up
+ip -n "$RB"   link set rb_b up
+ip -n "$RB"   link set rb_il up
+ip -n "$PEER" link set pe_a up
+ip -n "$PEER" link set pe_b up
+ip -n "$SAN"  link set san_il up
+ip -n "$SAN"  addr add 100.64.0.51/24 dev san_il
+
+# Feature gate: PRP interlink (RedBox) creation. A kernel without PRP RedBox
+# support rejects this with -EINVAL, so SKIP rather than FAIL.
+if ! ip -n "$RB" link add name prp0 type hsr slave1 rb_a slave2 rb_b \
+     interlink rb_il proto 1 2>/dev/null; then
+	echo "SKIP: kernel without PRP RedBox (interlink) support"
+	exit $ksft_skip
+fi
+ip -n "$RB"   link set prp0 up
+ip -n "$PEER" link add name prp0 type hsr slave1 pe_a slave2 pe_b proto 1
+ip -n "$PEER" link set prp0 up
+ip -n "$PEER" addr add 100.64.0.2/24 dev prp0
+sleep 1
+
+san_mac=$(ip -n "$SAN" -br link show san_il | awk '{print $3}')
+rb_mac=$(ip -n "$RB" -br link show rb_il | awk '{print $3}')
+
+# Bidirectional unicast across the interlink.
+do_ping "$PEER" 100.64.0.51
+do_ping "$SAN"  100.64.0.2
+stop_if_error "PRP RedBox bidirectional unicast failed"
+
+# The SAN source MAC must be preserved on the PRP network, not laundered to the
+# RedBox MAC: the peer resolves the SAN IP to the SAN's own MAC.
+neigh=$(ip -n "$PEER" neigh show 100.64.0.51 | awk '{print $5}')
+if [ "$neigh" != "$san_mac" ]; then
+	echo "SAN MAC preservation [ FAIL ]: peer resolved 100.64.0.51 to" \
+	     "'$neigh', expected $san_mac" 1>&2
+	ret=1
+fi
+stop_if_error "SAN MAC not preserved on the PRP network"
+
+# The proxy-announce supervision frame must carry, in order, the life-check TLV
+# (type 0x14, len 6) + MacAddressA == SAN MAC + the RedBox-MAC TLV (type 0x1e,
+# len 6) + MacAddressRedBox == RedBox MAC + the EOT marker (0x0000).
+( ip netns exec "$SAN" ping -i 0.2 -q 100.64.0.2 >/dev/null 2>&1 & )
+cap=$(ip netns exec "$PEER" timeout 5 tcpdump -i pe_a -nn -x \
+	"ether proto 0x88fb and ether src $rb_mac" 2>/dev/null || true)
+ip netns exec "$SAN" pkill -f "ping -i 0.2" 2>/dev/null || true
+
+san_hex=$(echo "$san_mac" | tr -d ':')
+rb_hex=$(echo "$rb_mac" | tr -d ':')
+# Reassemble contiguous frame hex: drop the "0x0010:" offset labels and spaces.
+frame_hex=$(echo "$cap" | awk '/^[[:space:]]*0x[0-9a-f]+:/ {
+	sub(/^[[:space:]]*0x[0-9a-f]+:[[:space:]]*/, ""); gsub(/ /, ""); printf "%s", $0 }')
+if ! echo "$frame_hex" | grep -q "1406${san_hex}1e06${rb_hex}0000"; then
+	echo "supervision RedBox-MAC TLV [ FAIL ]: missing SAN MAC, Type-30" \
+	     "payload, or EOT" 1>&2
+	ret=1
+fi
+stop_if_error "PRP RedBox supervision RedBox-MAC TLV/EOT check failed"
+
+echo "INFO: PRP RedBox (PRP-SAN) conformance checks passed"
+exit $ret
-- 
2.53.0