meta-google: gbmc-bridge: Implement DHCP

This makes it possible for a BMC to acquire a public address via DHCP
provisioning.

None of the update processes are included yet.

Change-Id: I51ca2aa4859bcd2b9e909dd5a0d9e66cfbd648af
Signed-off-by: William A. Kennington III <wak@google.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-dhcp.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-dhcp.sh
new file mode 100644
index 000000000..beccc8658
--- /dev/null
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-dhcp.sh
@@ -0,0 +1,96 @@
+#!/bin/bash
+# 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.
+
+# A list of functions which get executed for each bound DHCP lease.
+# These are configured by the files included below.
+GBMC_BR_DHCP_HOOKS=()
+
+# Load configurations from a known location in the filesystem to populate
+# hooks that are executed after each event.
+shopt -s nullglob
+for conf in /usr/share/gbmc-br-dhcp/*.sh; do
+  # SC doesn't like dynamic source loading
+  # shellcheck disable=SC1090
+  source "$conf"
+done
+
+gbmc_br_dhcp_run_hooks() {
+  local hook
+  for hook in "${GBMC_BR_DHCP_HOOKS[@]}"; do
+    "$hook" || continue
+  done
+}
+
+# SC can't find this path during repotest
+# shellcheck disable=SC1091
+source /usr/share/network/lib.sh || exit
+
+if [ "$1" = bound ]; then
+  # Variable is from the environment via udhcpc6
+  # shellcheck disable=SC2154
+  echo "DHCPv6(gbmcbr): $ipv6/128" >&2
+
+  pfx_bytes=()
+  ip_to_bytes pfx_bytes "$ipv6"
+  # Ensure we are a BMC and have a suffix nibble, the 0th index is reserved
+  if (( pfx_bytes[8] != 0xfd || pfx_bytes[9] & 0xf == 0 )); then
+    echo "Invalid address" >&2
+    exit
+  fi
+  # Ensure we don't have more than a /80 address
+  for (( i = 10; i < 16; ++i )); do
+    if (( pfx_bytes[i] != 0 )); then
+      echo "Invalid address" >&2
+      exit
+    fi
+  done
+
+  pfx="$(ip_bytes_to_str pfx_bytes)"
+  (( pfx_bytes[9] &= 0xf0 ))
+  stateless_pfx="$(ip_bytes_to_str pfx_bytes)"
+  read -r -d '' contents <<EOF
+[Network]
+Address=$pfx/128
+IPv6PrefixDelegation=yes
+[IPv6PrefixDelegation]
+RouterLifetimeSec=60
+[IPv6Prefix]
+Prefix=$stateless_pfx/80
+PreferredLifetimeSec=60
+ValidLifetimeSec=60
+[IPv6RoutePrefix]
+Route=$pfx/80
+LifetimeSec=60
+[Route]
+Destination=$stateless_pfx/76
+Type=unreachable
+Metric=1024
+EOF
+
+  for file in /etc/systemd/network/{00,}-bmc-gbmcbr.network.d/50-public.conf; do
+    mkdir -p "$(dirname "$file")"
+    printf '%s' "$contents" >"$file"
+  done
+
+  # Ensure that systemd-networkd performs a reconfiguration as it doesn't
+  # currently check the mtime of drop-in files.
+  touch -c /lib/systemd/network/*-bmc-gbmcbr.network
+
+  if [ "$(systemctl is-active systemd-networkd)" != 'inactive' ]; then
+    networkctl reload && networkctl reconfigure gbmcbr
+  fi
+
+  gbmc_br_dhcp_run_hooks
+fi