#!/bin/bash # SPDX-License-Identifier: GPL-2.0 # Test for checking ICMP response with dummy address instead of 0.0.0.0. # Sets up two namespaces like: # +----------------------+ +--------------------+ # | ns1 | v4-via-v6 routes: | ns2 | # | | ' | | # | +--------+ -> 172.16.1.0/24 -> +--------+ | # | | veth0 +--------------------------+ veth0 | | # | +--------+ <- 172.16.0.0/24 <- +--------+ | # | 172.16.0.1 | | 2001:db8:1::2/64 | # | 2001:db8:1::2/64 | | | # +----------------------+ +--------------------+ # # And then tries to ping 172.16.1.1 from ns1. This results in a "net # unreachable" message being sent from ns2, but there is no IPv4 address set in # that address space, so the kernel should substitute the dummy address # 192.0.0.8 defined in RFC7600. source lib.sh H1_IP=172.16.0.1/32 H1_IP6=2001:db8:1::1 RT1=172.16.1.0/24 PINGADDR=172.16.1.1 RT2=172.16.0.0/24 H2_IP6=2001:db8:1::2 TMPFILE=$(mktemp) cleanup() { rm -f "$TMPFILE" cleanup_ns $NS1 $NS2 } trap cleanup EXIT # Namespaces setup_ns NS1 NS2 # Connectivity ip -netns $NS1 link add veth0 type veth peer name veth0 netns $NS2 ip -netns $NS1 link set dev veth0 up ip -netns $NS2 link set dev veth0 up ip -netns $NS1 addr add $H1_IP dev veth0 ip -netns $NS1 addr add $H1_IP6/64 dev veth0 nodad ip -netns $NS2 addr add $H2_IP6/64 dev veth0 nodad ip -netns $NS1 route add $RT1 via inet6 $H2_IP6 ip -netns $NS2 route add $RT2 via inet6 $H1_IP6 # Make sure ns2 will respond with ICMP unreachable ip netns exec $NS2 sysctl -qw net.ipv4.icmp_ratelimit=0 net.ipv4.ip_forward=1 # Run the test - a ping runs in the background, and we capture ICMP responses # with tcpdump; -c 1 means it should exit on the first ping, but add a timeout # in case something goes wrong ip netns exec $NS1 ping -w 3 -i 0.5 $PINGADDR >/dev/null & ip netns exec $NS1 timeout 10 tcpdump -tpni veth0 -c 1 'icmp and icmp[icmptype] != icmp-echo' > $TMPFILE 2>/dev/null # Parse response and check for dummy address # tcpdump output looks like: # IP 192.0.0.8 > 172.16.0.1: ICMP net 172.16.1.1 unreachable, length 92 RESP_IP=$(awk '{print $2}' < $TMPFILE) if [[ "$RESP_IP" != "192.0.0.8" ]]; then echo "FAIL - got ICMP response from $RESP_IP, should be 192.0.0.8" exit 1 else echo "OK" exit 0 fi