#!/bin/bash

# Copyright (C) 2009 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


# This is an example ganeti hook that sets up an IPsec ESP link between all the
# nodes of a cluster for a given list of protocols.

# When run on cluster initialization it will create the shared key to be used
# for all the links. When run on node add/removal it will reconfigure IPsec
# on each node of the cluster.

set -e

LOCALSTATEDIR=@LOCALSTATEDIR@
SYSCONFDIR=@SYSCONFDIR@

GNTDATA=${LOCALSTATEDIR}/lib/ganeti

LOCKFILE=${LOCALSTATEDIR}/lock/ganeti_ipsec
CRYPTALGO=rijndael-cbc
KEYPATH=${GNTDATA}/ipsec.key
KEYSIZE=24
PROTOSTOSEC="icmp tcp"
TCPTOIGNORE="22 1811"
# On debian/ubuntu this file is automatically reloaded on boot
SETKEYCONF=${SYSCONFDIR}/ipsec-tools.conf
SETKEYCUSTOMCONF=${SYSCONFDIR}/ipsec-tools-custom.conf
AUTOMATIC_MARKER="# Automatically generated rules"
REGEN_KEY_WAIT=2

NODES=${GNTDATA}/ssconf_node_secondary_ips
MASTERNAME_FILE=${GNTDATA}/ssconf_master_node
MASTERIP_FILE=${GNTDATA}/ssconf_master_ip

SSHOPTS="-q -oUserKnownHostsFile=/dev/null -oStrictHostKeyChecking=no \
         -oGlobalKnownHostsFile=${GNTDATA}/known_hosts"
SCPOPTS="-p $SSHOPTS"

CLEANUP=( )

cleanup() {
  # Perform all registered cleanup operation
  local i
  for (( i=${#CLEANUP[@]}; i >= 0 ; --i )); do
    ${CLEANUP[$i]}
  done
}

acquire_lockfile() {
  # Acquire the lockfile associated with system ipsec configuration.
  lockfile-create "$LOCKFILE" || exit 1
  CLEANUP+=("lockfile-remove $LOCKFILE")
}

update_system_ipsec() {
  # Update system ipsec configuration.
  # $1 : temporary location of a working configuration
  local TMPCONF="$1"
  acquire_lockfile
  mv "$TMPCONF" "$SETKEYCONF"
  setkey -f "$SETKEYCONF"
}

update_keyfile() {
  # Obtain the IPsec keyfile from the master.
  local MASTERIP=$(< "$MASTERIP_FILE")
  scp $SCPOPTS "$MASTERIP":"$KEYPATH" "$KEYPATH"
}

gather_key() {
  # Output IPsec key, if no key is present on the node
  # obtain it from master.
  if [[ ! -f "$KEYPATH" ]]; then
    update_keyfile
  fi
  cut -d ' ' -f2 "$KEYPATH"
}

gather_key_seqno() {
  # Output IPsec key sequence number, if no key is present
  # on the node exit with error.
  if [[ ! -f "$KEYPATH" ]]; then
    echo 'Cannot obtain key timestamp, no key file.' >&2
    exit 1
  fi
  cut -d ' ' -f1 "$KEYPATH"
}

update_ipsec_conf() {
  # Generate a new IPsec configuration and update the system.
  local TMPCONF=$(mktemp)
  CLEANUP+=("rm -f $TMPCONF")
  ESCAPED_HOSTNAME=$(sed 's/\./\\./g' <<< "$HOSTNAME")
  local MYADDR=$(grep -E "^$ESCAPED_HOSTNAME\\>" "$NODES" | cut -d ' ' -f2)
  local KEY=$(gather_key)
  local SETKEYPATH=$(which setkey)

  {
  echo "#!$SETKEYPATH -f"
  echo
  echo "# Configuration for $MYADDR"
  echo
  echo '# This file has been automatically generated. Do not modify by hand,'
  echo "# add your own rules to $SETKEYCUSTOMCONF instead."
  echo
  echo '# Flush SAD and SPD'
  echo 'flush;'
  echo 'spdflush;'
  echo
  if [[ -f "$SETKEYCUSTOMCONF" ]]; then
    echo "# Begin custom rules from $SETKEYCUSTOMCONF"
    cat "$SETKEYCUSTOMCONF"
    echo "# End custom rules from $SETKEYCUSTOMCONF"
    echo
  fi
  echo "$AUTOMATIC_MARKER"
  for node in $(cut -d ' ' -f2 "$NODES") ; do
    if [[ "$node" != "$MYADDR" ]]; then
      # Traffic to ignore
      for port in $TCPTOIGNORE ; do
        echo "spdadd $MYADDR[$port] $node tcp -P out none;"
        echo "spdadd $node $MYADDR[$port] tcp -P in none;"
        echo "spdadd $MYADDR $node[$port] tcp -P out none;"
        echo "spdadd $node[$port] $MYADDR tcp -P in none;"
      done
      # IPsec ESP rules
      echo "add $MYADDR $node esp 0x201 -E $CRYPTALGO $KEY;"
      echo "add $node $MYADDR esp 0x201 -E $CRYPTALGO $KEY;"
      for proto in $PROTOSTOSEC ; do
        echo "spdadd $MYADDR $node $proto -P out ipsec esp/transport//require;"
        echo "spdadd $node $MYADDR $proto -P in ipsec esp/transport//require;"
      done
      echo
    fi
  done
  } > "$TMPCONF"

  chmod 400 "$TMPCONF"
  update_system_ipsec "$TMPCONF"
}

regen_ipsec_conf() {
  # Reconfigure IPsec on the system when a new key is generated
  # on the master (assuming the current configuration is working
  # and a new key is about to be generated on the master).
  if [[ ! -f "$KEYPATH" ]]; then
    echo 'Asking to regenerate with new key, but no old key.' >&2
    exit 1
  fi
  local CURSEQNO=$(gather_key_seqno)
  update_keyfile
  local NEWSEQNO=$(gather_key_seqno)
  while [[ $NEWSEQNO -le $CURSEQNO ]]; do
    # Master did not update yet, wait..
    sleep $REGEN_KEY_WAIT
    update_keyfile
    NEWSEQNO=$(gather_key_seqno)
  done
  update_ipsec_conf
}

clean_ipsec_conf() {
  # Unconfigure IPsec on the system, removing the key and
  # the rules previously generated.
  rm -f "$KEYPATH"

  local TMPCONF=$(mktemp)
  CLEANUP+=("rm -f $TMPCONF")
  # Remove all auto-generated rules
  sed "/$AUTOMATIC_MARKER/q" "$SETKEYCONF" > "$TMPCONF"
  chmod 400 "$TMPCONF"
  update_system_ipsec "$TMPCONF"
}

generate_secret() {
  # Generate a random HEX string (length specified by global variable KEYSIZE)
  python -c "from ganeti import utils; print utils.GenerateSecret($KEYSIZE)"
}

gen_key() {
  # Generate a new random key to be used for IPsec, the key is associated with
  # a sequence number.
  local KEY=$(generate_secret)
  if [[ ! -f "$KEYPATH" ]]; then
    # New environment/cluster, let's start from scratch
    local SEQNO="0"
  else
    local SEQNO=$(( $(gather_key_seqno) + 1 ))
  fi
  local TMPKEYPATH=$(mktemp)
  CLEANUP+=("rm -f $TMPKEYPATH")
  echo -n "$SEQNO 0x$KEY" > "$TMPKEYPATH"
  chmod 400 "$TMPKEYPATH"
  mv "$TMPKEYPATH" "$KEYPATH"
}

trap cleanup EXIT

hooks_path="$GANETI_HOOKS_PATH"
if [[ ! -n "$hooks_path" ]]; then
  echo '\$GANETI_HOOKS_PATH not specified.' >&2
  exit 1
fi
hooks_phase="$GANETI_HOOKS_PHASE"
if [[ ! -n "$hooks_phase" ]]; then
  echo '\$GANETI_HOOKS_PHASE not specified.' >&2
  exit 1
fi

if [[ "$hooks_phase" = post ]]; then
  case "$hooks_path" in
    cluster-init)
        gen_key
        ;;
    cluster-destroy)
        clean_ipsec_conf
        ;;
    cluster-regenkey)
        # This hook path is not yet implemented in Ganeti, here we suppose it
        # runs on all the nodes.
        MASTERNAME=$(< "$MASTERNAME_FILE")
        if [[ "$MASTERNAME" = "$HOSTNAME" ]]; then
          gen_key
          update_ipsec_conf
        else
          regen_ipsec_conf
        fi
        ;;
    node-add)
        update_ipsec_conf
        ;;
    node-remove)
        node_name="$GANETI_NODE_NAME"
        if [[ ! -n "$node_name" ]]; then
          echo '\$GANETI_NODE_NAME not specified.' >&2
          exit 1
        fi
        if [[ "$node_name" = "$HOSTNAME" ]]; then
          clean_ipsec_conf
        else
          update_ipsec_conf
        fi
        ;;
    *)
        echo "Hooks path $hooks_path is not for us." >&2
        ;;
  esac
else
  echo "Hooks phase $hooks_phase is not for us." >&2
fi