# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

[ -z "${gbmc_ncsi_br_deprecated_ips_lib-}" ] || return

source /usr/share/network/lib.sh || exit

gbmc_ncsi_br_deprecated_ips_init=
gbmc_ncsi_br_deprecated_ips_confip=
gbmc_ncsi_br_deprecated_ips_lastip=

gbmc_ncsi_br_deprecated_ips_addr_contents() {
  local addr="$1"

  # If our address is assigned explicitly, don't mark it deprecated
  local line
  for line in $(grep '^Address=' /etc/systemd/network/*-bmc-@NCSI_IF@.network); do
    # Remove `Address=` on the input line
    local apfx="$(echo "$line" | sed 's,^[^=]*=,,')"
    # ip_pfx_concat is used to normalize the address string for comparison
    [[ "$addr/128" == "$(ip_pfx_concat "$apfx" ::)" ]] && return
  done

  cat <<EOF
[Address]
Address=$addr/128
PreferredLifetime=0
EOF
}

gbmc_ncsi_br_deprecated_ips_host_contents() {
  local addr="$1"

  cat <<EOF
[Network]
IPv6ProxyNDP=yes
IPv6ProxyNDPAddress=$addr
EOF
}

gbmc_ncsi_br_deprecated_ips_update() {
  [ -n "$gbmc_ncsi_br_deprecated_ips_init" ] || return
  [ "$gbmc_ncsi_br_deprecated_ips_confip" != "$gbmc_ncsi_br_deprecated_ips_lastip" ] || return
  gbmc_ncsi_br_deprecated_ips_confip="$gbmc_ncsi_br_deprecated_ips_lastip"

  printf 'gBMC Bridge NCSI Deprecated Addrs: %s\n' \
    "${gbmc_ncsi_br_deprecated_ips_lastip:-(deleted)}" >&2

  local contents=
  local nfcontents=
  if [ -n "$gbmc_ncsi_br_deprecated_ips_lastip" ]; then
    local pfx_bytes=()
    ip_to_bytes pfx_bytes "$gbmc_ncsi_br_deprecated_ips_lastip"

    local pfx="$(ip_bytes_to_str pfx_bytes)"
    (( pfx_bytes[9] &= 0xf0 ))
    local stateless_pfx="$(ip_bytes_to_str pfx_bytes)"
    local gbmcbr_mac="$(ip link show gbmcbr | tail -n 1 | awk '{print $2}')"
    local gbmcbr_eui48="$(mac_to_eui48 "$gbmcbr_mac")"
    local stateless_ip="$(ip_pfx_concat "$stateless_pfx/80" "$gbmcbr_eui48")"
    stateless_ip="${stateless_ip%/*}"
    pfx_bytes[8]=0
    pfx_bytes[9]=0
    local host_pfx="$(ip_bytes_to_str pfx_bytes)"
    contents+="$(gbmc_ncsi_br_deprecated_ips_addr_contents "$pfx")"$'\n'
    contents+="$(gbmc_ncsi_br_deprecated_ips_addr_contents "$stateless_pfx")"$'\n'
    contents+="$(gbmc_ncsi_br_deprecated_ips_addr_contents "$stateless_ip")"$'\n'
    contents+="$(gbmc_ncsi_br_deprecated_ips_host_contents "$host_pfx")"$'\n'
    read -r -d '' nfcontents <<EOF
table inet filter {
  chain ncsi_input {
    ip6 saddr != $pfx/76 ip6 daddr $pfx/76 goto ncsi_gbmc_br_pub_input
  }
  chain ncsi_forward {
    ip6 saddr != $pfx/76 ip6 daddr $pfx/76 accept
  }
}
EOF
  fi

  local file
  for file in /run/systemd/network/{00,}-bmc-@NCSI_IF@.network.d/50-deprecated.conf; do
    mkdir -p -m 755 "$(dirname "$file")"
    if [ -z "$contents" ]; then
      rm -f "$file"
    else
      printf '%s' "$contents" >"$file"
    fi
  done

  # Ensure that systemd-networkd performs a reconfiguration as it doesn't
  # currently check the mtime of drop-in files.
  touch -c /etc/systemd/network/*-bmc-@NCSI_IF@.network

  if [ "$(systemctl is-active systemd-networkd)" != 'inactive' ]; then
    networkctl reload && networkctl reconfigure @NCSI_IF@
  fi

  local rfile=/run/nftables/40-gbmc-ncsi-br.rules
  mkdir -p -m 755 "$(dirname "$rfile")"
  if [ -z "$nfcontents" ]; then
    rm -f "$rfile"
  else
    printf '%s' "$nfcontents" >"$rfile"
  fi
  systemctl reset-failed nftables && systemctl --no-block reload-or-restart nftables || true
}

gbmc_ncsi_br_deprecated_ips_hook() {
  if [ "$change" = 'init' ]; then
    gbmc_ncsi_br_deprecated_ips_init=1
    gbmc_ip_monitor_defer
  elif [ "$change" = 'defer' ]; then
    gbmc_ncsi_br_deprecated_ips_update
  elif [ "$change" = 'addr' -a "$intf" = 'gbmcbr' ] &&
     [ "$scope" = 'global' -a "$fam" = 'inet6' ]; then
    local pfx_bytes=()
    ip_to_bytes pfx_bytes "$ip" || return
    # No ULA Addresses
    if (( pfx_bytes[0] & 0xfe == 0xfc )); then
      return
    fi
    # We only want to allow a <pfx>::fd0x address, where x>0
    if (( pfx_bytes[8] != 0xfd || pfx_bytes[9] & 0xf == 0 )); then
      return
    fi
    for (( i = 10; i < 16; ++i )); do
      if (( pfx_bytes[i] != 0 )); then
        return
      fi
    done
    if [ "$action" = 'add' -a "$ip" != "$gbmc_ncsi_br_deprecated_ips_lastip" ]; then
      gbmc_ncsi_br_deprecated_ips_lastip="$ip"
      gbmc_ip_monitor_defer
    fi
    if [ "$action" = 'del' -a "$ip" = "$gbmc_ncsi_br_deprecated_ips_lastip" ]; then
      gbmc_ncsi_br_deprecated_ips_lastip=
      gbmc_ip_monitor_defer
    fi
  fi
}

GBMC_IP_MONITOR_HOOKS+=(gbmc_ncsi_br_deprecated_ips_hook)

gbmc_ncsi_br_deprecated_ips_lib=1