1 #!/bin/bash
2 # SPDX-License-Identifier: GPL-2.0
3
4 # Test for checking ICMP response with dummy address instead of 0.0.0.0.
5 # Sets up two namespaces like:
6 # +----------------------+ +--------------------+
7 # | ns1 | v4-via-v6 routes: | ns2 |
8 # | | ' | |
9 # | +--------+ -> 172.16.1.0/24 -> +--------+ |
10 # | | veth0 +--------------------------+ veth0 | |
11 # | +--------+ <- 172.16.0.0/24 <- +--------+ |
12 # | 172.16.0.1 | | 2001:db8:1::2/64 |
13 # | 2001:db8:1::2/64 | | |
14 # +----------------------+ +--------------------+
15 #
16 # And then tries to ping 172.16.1.1 from ns1. This results in a "net
17 # unreachable" message being sent from ns2, but there is no IPv4 address set in
18 # that address space, so the kernel should substitute the dummy address
19 # 192.0.0.8 defined in RFC7600.
20
21 source lib.sh
22
23 H1_IP=172.16.0.1/32
24 H1_IP6=2001:db8:1::1
25 RT1=172.16.1.0/24
26 PINGADDR=172.16.1.1
27 RT2=172.16.0.0/24
28 H2_IP6=2001:db8:1::2
29
30 TMPFILE=$(mktemp)
31
32 cleanup()
33 {
34 rm -f "$TMPFILE"
35 cleanup_ns $NS1 $NS2
36 }
37
38 trap cleanup EXIT
39
40 # Namespaces
41 setup_ns NS1 NS2
42
43 # Connectivity
44 ip -netns $NS1 link add veth0 type veth peer name veth0 netns $NS2
45 ip -netns $NS1 link set dev veth0 up
46 ip -netns $NS2 link set dev veth0 up
47 ip -netns $NS1 addr add $H1_IP dev veth0
48 ip -netns $NS1 addr add $H1_IP6/64 dev veth0 nodad
49 ip -netns $NS2 addr add $H2_IP6/64 dev veth0 nodad
50 ip -netns $NS1 route add $RT1 via inet6 $H2_IP6
51 ip -netns $NS2 route add $RT2 via inet6 $H1_IP6
52
53 # Make sure ns2 will respond with ICMP unreachable
54 ip netns exec $NS2 sysctl -qw net.ipv4.icmp_ratelimit=0 net.ipv4.ip_forward=1
55
56 # Run the test - a ping runs in the background, and we capture ICMP responses
57 # with tcpdump; -c 1 means it should exit on the first ping, but add a timeout
58 # in case something goes wrong
59 ip netns exec $NS1 ping -w 3 -i 0.5 $PINGADDR >/dev/null &
60 ip netns exec $NS1 timeout 10 tcpdump -tpni veth0 -c 1 'icmp and icmp[icmptype] != icmp-echo' > $TMPFILE 2>/dev/null
61
62 # Parse response and check for dummy address
63 # tcpdump output looks like:
64 # IP 192.0.0.8 > 172.16.0.1: ICMP net 172.16.1.1 unreachable, length 92
65 RESP_IP=$(awk '{print $2}' < $TMPFILE)
66 if [[ "$RESP_IP" != "192.0.0.8" ]]; then
67 echo "FAIL - got ICMP response from $RESP_IP, should be 192.0.0.8"
68 exit 1
69 else
70 echo "OK"
71 exit 0
72 fi
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