selftests: add route_localnet test script

#!/bin/bash

# SPDX-License-Identifier: GPL-2.0

#

# Run a couple of tests when route_localnet = 1.

readonly PEER_NS="ns-peer-$(mktemp -u XXXXXX)"

setup() {

    ip netns add "${PEER_NS}"

    ip -netns "${PEER_NS}" link set dev lo up

    ip link add name veth0 type veth peer name veth1

    ip link set dev veth0 up

    ip link set dev veth1 netns "${PEER_NS}"

    # Enable route_localnet and delete useless route 127.0.0.0/8.

    sysctl -w net.ipv4.conf.veth0.route_localnet=1

    ip netns exec "${PEER_NS}" sysctl -w net.ipv4.conf.veth1.route_localnet=1

    ip route del 127.0.0.0/8 dev lo table local

    ip netns exec "${PEER_NS}" ip route del 127.0.0.0/8 dev lo table local

    ifconfig veth0 127.25.3.4/24 up

    ip netns exec "${PEER_NS}" ifconfig veth1 127.25.3.14/24 up

    ip route flush cache

    ip netns exec "${PEER_NS}" ip route flush cache

}

cleanup() {

    ip link del veth0

    ip route add local 127.0.0.0/8 dev lo proto kernel scope host src 127.0.0.1

    local -r ns="$(ip netns list|grep $PEER_NS)"

    [ -n "$ns" ] && ip netns del $ns 2>/dev/null

}

# Run test when arp_announce = 2.

run_arp_announce_test() {

    echo "run arp_announce test"

    setup

    sysctl -w net.ipv4.conf.veth0.arp_announce=2

    ip netns exec "${PEER_NS}" sysctl -w net.ipv4.conf.veth1.arp_announce=2

    ping -c5 -I veth0 127.25.3.14

    if [ $? -ne 0 ];then

        echo "failed"

    else

        echo "ok"

    fi

    cleanup

}

# Run test when arp_ignore = 3.

run_arp_ignore_test() {

    echo "run arp_ignore test"

    setup

    sysctl -w net.ipv4.conf.veth0.arp_ignore=3

    ip netns exec "${PEER_NS}" sysctl -w net.ipv4.conf.veth1.arp_ignore=3

    ping -c5 -I veth0 127.25.3.14

    if [ $? -ne 0 ];then

        echo "failed"

    else

        echo "ok"

    fi

    cleanup

}

run_all_tests() {

    run_arp_announce_test

    run_arp_ignore_test

}

run_all_tests