1#!/bin/bash
2# Copyright 2021 Google LLC
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#      http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15
16[ ! -e /usr/share/gbmc-br-lib.sh ] && exit
17
18# shellcheck source=meta-google/recipes-google/networking/network-sh/lib.sh
19source /usr/share/network/lib.sh || exit
20# shellcheck source=meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-lib.sh
21source /usr/share/gbmc-br-lib.sh || exit
22
23NCSI_IF='@NCSI_IF@'
24
25old_pfx=
26old_fqdn=
27old_rtr=
28
29set_host() {
30  [[ -n "$host" && -n "$domain" && -n "$hextet" ]] || return
31
32  local fqdn="$host-n$hextet.$domain"
33  [ "$fqdn" != "$old_fqdn" ] || return
34  old_fqdn="$fqdn"
35
36  echo "Found hostname $fqdn" >&2
37  hostnamectl set-hostname "$fqdn" || true
38}
39
40set_net() {
41  [[ -n "$pfx" && -n "$rtr" ]] || return
42  [[ "$pfx" != "$old_pfx" || "$rtr" != "$old_rtr" ]] || return
43  old_pfx="$pfx"
44  old_rtr="$rtr"
45
46  echo "Found prefix $pfx from $rtr" >&2
47
48  # We no longer need NCSId if we are in this configuration
49  systemctl stop --no-block ncsid@"$NCSI_IF" || true
50
51  # Save the IP address for the interface
52  gbmc_br_set_ip "$pfx" || true
53
54  # DHCP Relay workaround until alternate source port is supported
55  # TODO: Remove this once internal relaying cleanups land
56  gbmc-ncsi-smartnic-wa.sh || true
57}
58
59w=60
60while true; do
61  start=$SECONDS
62  while read -r line; do
63    if [ -z "$line" ]; then
64      hextet=
65      pfx=
66      host=
67      domain=
68    elif [[ "$line" =~ ^Prefix' '*:' '*(.*)/([0-9]+)$ ]]; then
69      t_pfx="${BASH_REMATCH[1]}"
70      t_pfx_len="${BASH_REMATCH[2]}"
71      ip_to_bytes t_pfx_b "$t_pfx" || continue
72      (( t_pfx_len == 76 && t_pfx_b[8] & 0xfd == 0xfd )) || continue
73      (( t_pfx_b[9] |= 1 ))
74      hextet="fd$(printf '%02x' "${t_pfx_b[9]}")"
75      pfx="$(ip_bytes_to_str t_pfx_b)"
76    elif [[ "$line" =~ ^'DNS search list'' '*:' '*([^.]+)(.*[.]google[.]com)$ ]]; then
77      # Ideally, we use PCRE and with lookahead and can do this in a single regex
78      #   ^([a-zA-Z0-9-]+(?=-n[a-fA-F0-9]{1,4})|[a-zA-Z0-9-]+(?!-n[a-fA-F0-9]{1,4}))[^.]*[.]((?:[a-zA-Z0-9]*[.])*google[.]com)$
79      # Instead we do multiple steps to extract the needed info
80      host="${BASH_REMATCH[1]}"
81      domain="${BASH_REMATCH[2]#.}"
82      if [[ "$host" =~ (-n[a-fA-F0-9]{1,4})$ ]]; then
83        host="${host%"${BASH_REMATCH[1]}"}"
84      fi
85    elif [[ "$line" =~ ^from' '(.*)$ ]]; then
86      rtr="${BASH_REMATCH[1]}"
87      set_net || true
88      set_host || true
89    fi
90  done < <(rdisc6 -d -m "$NCSI_IF" -w $(( w * 1000 )) 2>/dev/null)
91  # If rdisc6 exits early we still want to wait the full `w` time before
92  # starting again.
93  (( timeout = start + w - SECONDS ))
94  sleep $(( timeout < 0 ? 0 : timeout ))
95done
96