#!/bin/bash
#============================================================================
# /etc/xen/vif-route-qubes
#
# Script for configuring a vif in routed mode.
# The hotplugging system will call this script if it is specified either in
# the device configuration given to Xend, or the default Xend configuration
# in /etc/xen/xend-config.sxp.  If the script is specified in neither of those
# places, then vif-bridge is the default.
#
# Usage:
# vif-route (add|remove|online|offline)
#
# Environment vars:
# vif         vif interface name (required).
# XENBUS_PATH path to this device's details in the XenStore (required).
#
# Read from the store:
# ip      list of IP networks for the vif, space-separated (default given in
#         this script).
#============================================================================

dir=$(dirname "$0")
# shellcheck disable=SC1091,SC1090
. "$dir/vif-common.sh"

set -o pipefail
#main_ip=$(dom0_ip)

# Network Hooks for triggering supplementary actions on AppVM connect
network_hooks() {
    local command="$1"
    local vif="$2"
    local addr="$3"

    local vif_type
    vif_type="$(xenstore-read "${XENBUS_PATH}/type")"

    if [ -d /rw/config/network-hooks.d ]; then
        for hook in /rw/config/network-hooks.d/*
        do
            if [ -x "$hook" ]; then
                log debug "Executing network-hook $(basename "$hook")..."
                do_without_error "${hook}" "${command}" "${vif}" "${vif_type}" "${addr}"
            fi
        done
    fi
}

conntrack_purge () {
    local n output deleted msg
    n='(0|[1-9][0-9]*)' msg='flow entries have been deleted\.$'
    deleted="^conntrack v$n\\.$n\\.$n \\(conntrack-tools\\): $n $msg"
    output=$(LC_ALL=C exec conntrack -D "$@" 2>&1 >/dev/null) || :
    [[ "$output" =~ $deleted ]]
}

ipt_arg=
if "iptables-restore" --help 2>&1 | grep -q wait=; then
    # 'wait' must be last on command line if secs not specified
    ipt_arg=--wait
fi

# shellcheck disable=SC2154
if [ "${ip}" ]; then
    # get first IPv4 and first IPv6
    for addr in ${ip}; do
        if [ -z "$ip4" ] && [[ "$addr" = *.* ]]; then
            ip4="$addr"
        elif [ -z "$ip6" ] && [[ "$addr" = *:* ]]; then
            ip6="$addr"
        fi
    done
    # IPs as seen by this VM
    netvm_ip="$ip4"
    netvm_gw_ip=$(qubesdb-read /qubes-netvm-gateway)
    netvm_gw_ip6=$(qubesdb-read /qubes-netvm-gateway6 || :)
    netvm_dns1_ip=$(qubesdb-read /qubes-netvm-primary-dns)
    netvm_dns2_ip=$(qubesdb-read /qubes-netvm-secondary-dns)

    back_ip="$netvm_gw_ip"
    back_ip6="$netvm_gw_ip6"

    # IPs as seen by the VM - if other than $netvm_ip
    appvm_gw_ip="$(qubesdb-read "/mapped-ip/$ip4/visible-gateway" 2>/dev/null || :)"
    appvm_ip="$(qubesdb-read "/mapped-ip/$ip4/visible-ip" 2>/dev/null || :)"
fi

readonly max_domid=32752

# This comment used to say, “if domid is 0 something is seriously wrong, so
# don’t check for that case”.  Indeed, dom0 should never have an Ethernet
# connection in a production QubesOS system.
#
# However, giving dom0 an Ethernet connection can be extremely useful in
# insecure test environments, where there is simply no data worth compromising.
# In fact, some test setups, including OpenQA, actually do this.  Therefore, we
# now handle this case correctly, even though it is by definition a security
# risk.
if ! [[ $vif =~ ^vif(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)$ ]]; then
    printf 'Bad interface name %q\n' "$vif">&2
    exit 1
fi

domid=${BASH_REMATCH[1]} sub=${BASH_REMATCH[2]}

# metric must be positive, but prefer later interface
#  32752 is max XID aka domid
#  the length check ensures there is no overflow
if (( "${#domid}" > "${#max_domid}" || domid > max_domid )); then
    printf %s\\n "domid $domid too large"
    exit 1
fi
metric=$(( max_domid - domid ))

# shellcheck disable=SC2154
case "$command" in
    online)
        echo 1 >"/proc/sys/net/ipv4/conf/${vif}/proxy_arp"
        ipcmd='add'
        iptables_cmd='-I PREROUTING 1'
        cmdprefix=''
        ipv6_disabled=$(cat /proc/sys/net/ipv6/conf/"${vif}"/disable_ipv6 || echo 1)
        # without a MAC address we will fail later with a confusing error
        mac=$(xenstore-read "backend/vif/$domid/$sub/mac") || exit 1
        ;;
    offline)
        do_without_error ifdown "${vif}"
        ipcmd='del'
        iptables_cmd='-D PREROUTING'
        cmdprefix='do_without_error'
        # cleanup IPv6 config even if _now_ it is disabled
        ipv6_disabled=0
        ;;
esac

# Apply NAT if IP visible from the VM is different than the "real" one
# See vif-qubes-nat.sh for details
# XXX: supported only for the first IPv4 address, IPv6 is dropped if this
# feature is enabled
if [ -n "$appvm_ip" ] && [ -n "$appvm_gw_ip" ] && [ "$appvm_ip" != "$netvm_ip" ]; then
    # shellcheck source=network/vif-qubes-nat.sh
    . "$dir/vif-qubes-nat.sh"
fi

case $- in
(*e*) :;;
(*) echo '-e not set'>&2; exit 1;;
esac

# add anti-spoofing rules before enabling the interface
if [ "${ip}" ]; then
    # If we’ve been given a list of IP addresses, then add routes from us to
    # the VMs we serve using those addresses.
    for addr in ${ip};
    do
        if [[ "$addr" = *:* ]]; then
            ipt=ip6tables-restore
        else
            ipt=iptables-restore
        fi
        printf '%s\n' "*raw" \
            "$iptables_cmd -i ${vif} ! -s ${addr} -j DROP" \
            "$iptables_cmd ! -i vif+ -s ${addr} -j DROP" \
            "COMMIT" |
            ${cmdprefix} "$ipt" --noflush $ipt_arg
        if [[ "$command" = 'online' ]]; then
            ip -- neighbour "${ipcmd}" to "${addr}" \
                dev "${vif}" lladdr "$mac" nud permanent
        fi
        if ! conntrack_purge -s "$addr" || ! conntrack_purge -d "$addr"; then
            printf 'Cannot purge stale conntrack entries for %q\n' "$addr">&2
            exit 1
        fi
    done
    # if no IPv6 is assigned, block all IPv6 traffic on that interface
    if ! [[ "$ip" = *:* ]]; then
        echo -e "*raw\\n$iptables_cmd -i ${vif} -j DROP\\nCOMMIT" |
            ${cmdprefix} ip6tables-restore --noflush $ipt_arg
    fi
fi

if [ "$command" = "online" ]; then
    ifconfig "${vif}" up
fi

if [ "${ip}" ]; then
    # If we've been given a list of IP addresses, then add routes from dom0 to
    # the guest using those addresses.
    for addr in ${ip};
    do
        if [[ "$addr" = *:* ]] && [[ "$ipv6_disabled" = 1 ]]; then
            log error "Cannot set IPv6 route to ${addr}, IPv6 disabled in the kernel"
            continue
        fi
        ${cmdprefix} ip route "${ipcmd}" "${addr}" dev "${vif}" metric "$metric"

        network_hooks "${command}" "${vif}" "${addr}"
    done
    ${cmdprefix} ip addr "${ipcmd}" "${back_ip}/32" dev "${vif}"
    if [ "${back_ip6}" ] && [[ "${back_ip6}" != "fe80:"* ]] && [[ "$ipv6_disabled" != 1 ]]; then
        ${cmdprefix} ip addr "${ipcmd}" "${back_ip6}/128" dev "${vif}"
    fi
else
    network_hooks "${command}" "${vif}"
fi

log debug "Successful vif-route-qubes $command for $vif."
if [ "$command" = "online" ]; then
  success
fi