#!/bin/bash

# Configuration Fallbacks. All can(must for some of them) be overwritten by /etc/default/snf-network
TTL=300
# the bind server IP/FQDN
SERVER=""
# this is the .vm.synnefo.live.
# Leave empty if only reverse dns management is needed.
# TODO: make this zone to be instance specific!!!
FZONE=""
# the file with dns authorization keys
KEYFILE=""
MAC2EUI64="/usr/bin/mac2eui64"

source /etc/default/snf-network
source /usr/lib/snf-network/common.sh

if [ -z "$SERVER" -o -z "$FZONE" -o ! -e "$KEYFILE" ]; then
  exit 0
fi

update () {
	local ZONE=$1
	local action="$2"
	nsupdate -k $KEYFILE > /dev/null << EOF
	server $SERVER
	zone $ZONE
	$action
	send
EOF
}


# ommit zone statement
# nsupdate  will attempt determine the correct zone to update based on the rest of the input
send_command () {

  local command="$1"
  hooks-log dnshook "$command"
  nsupdate -k $KEYFILE > /dev/null << EOF
  server $SERVER
  $command
  send
EOF

}


update_arecord () {

  local action=$1
  local command=
  if [ -n "$IP" ]; then
    command="update $action $GANETI_INSTANCE_NAME.$FZONE $TTL A $IP"
    send_command "$command"
  fi

}


update_aaaarecord () {

  local action=$1
  local command=
  if [ -n "$EUI64" ]; then
    command="update $action $GANETI_INSTANCE_NAME.$FZONE $TTL AAAA $EUI64"
    send_command "$command"
  fi

}


update_ptrrecord () {

  local action=$1
  local command=
  if [ -n "$IP" ]; then
    command="update $action $RLPART.$RZONE. $TTL PTR $GANETI_INSTANCE_NAME.$FZONE"
    send_command "$command"
  fi

}

update_ptr6record () {

  local action=$1
  local command=
  if [ -n "$EUI64" ]; then
    command="update $action $R6LPART$R6ZONE. $TTL PTR $GANETI_INSTANCE_NAME.$FZONE"
    send_command "$command"
  fi

}

update_all () {

  local action=$1
  update_arecord $action
  update_aaaarecord $action
  update_ptrrecord $action
  update_ptr6record $action

}


# first argument is an eui64 (IPv6)
# sets GLOBAL args R6REC, R6ZONE, R6LPART
# lets assume eui64=2001:648:2ffc:1::1
# the following commands produce:
# R6REC=1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.0.c.f.f.2.8.4.6.0.1.0.0.2.ip6.arpa
# R6ZONE=1.0.0.0.c.f.f.2.8.4.6.0.1.0.0.2.ip6.arpa
# R6LPART=1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
get_rev6_info () {

  local eui64=$1
  if [ -z "$eui64" ]; then
    R6REC= ; R6ZONE= ; R6LPART= ;
  else
    R6REC=$(host $eui64 | egrep -o '([[:alnum:]]\.){32}ip6.arpa' )
    R6ZONE=$(echo $R6REC | awk -F. 'BEGIN{rpart="";} { for (i=32;i>16;i=i-1) rpart=$i "." rpart; } END{print rpart "ip6.arpa";}')
    R6LPART=$(echo $R6REC | awk -F. 'BEGIN{lpart="";} { for (i=16;i>0;i=i-1) lpart=$i "." lpart; } END{print lpart;}')
  fi

}


# first argument is an ipv4
# sets args RZONE, RLPART
# lets assume IP=203.0.113.1
# RZONE="113.0.203.in-add.arpa"
# RLPART="1"
get_rev4_info () {

  local ip=$1
  if [ -z "$ip" ]; then
    RZONE= ; RLPART= ;
  else
    OLDIFS=$IFS
    IFS=". "
    set -- $ip
    a=$1 ; b=$2; c=$3; d=$4;
    IFS=$OLDIFS
    RZONE="$c.$b.$a.in-addr.arpa"
    RLPART="$d"
  fi

}


update_dns () {

  if [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_CREATE" ]; then
    update_all add
  elif [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_REMOVE" ]; then
    update_all delete
  elif [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_RENAME" ]; then
    update_all delete
    # Let's override a variable and add ourselves
    GANETI_INSTANCE_NAME=$GANETI_INSTANCE_NEW_NAME
    update_all add
  elif [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_STARTUP" ]; then
    update_all add
  elif [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_SHUTDOWN" ]; then
    update_all delete
  elif [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_REBOOT" ]; then
    update_all add
  elif [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_SET_PARAMS" ]; then
    update_all add
  fi

}


# Query nameserver for entries related to the specific instance
# An example output is the following:
# www.google.com has address 173.194.113.114
# www.google.com has address 173.194.113.115
# www.google.com has address 173.194.113.116
# www.google.com has address 173.194.113.112
# www.google.com has address 173.194.113.113
# www.google.com has IPv6 address 2a00:1450:4001:80b::1012
query_dns () {

  HOSTQ="host -s -R 3 -W 3"
  HOST_IP_ALL=$($HOSTQ $GANETI_INSTANCE_NAME.$FZONE $SERVER | sed -n 's/.*has address //p')
  HOST_IP6_ALL=$($HOSTQ $GANETI_INSTANCE_NAME.$FZONE $SERVER | sed -n 's/.*has IPv6 address //p')

}


# Reset all entries related to the specific instance
# This should be invoced only during instance modification
# because we do not know which nics have been modify
reset_dns () {

  if [ "x$GANETI_OP_CODE" = "xOP_INSTANCE_SET_PARAMS" ]; then
    query_dns
    # This should remove the A, AAAA, CNAME entries
    send_command "update delete $GANETI_INSTANCE_NAME.$FZONE"
    for ip in $HOST_IP_ALL; do
      get_rev4_info $ip
      # This should remove the IPv4 reverse entry
      send_command "update delete $RLPART.$RZONE"
    done
    for ip6 in $HOST_IP6_ALL; do
      get_rev6_info $ip6
      # This should remove the IPv6 reverse entry
      send_command "update delete $R6LPART$R6ZONE."
    done
  fi

}


# Main starts here


# Exit if we do not have instance name.
# It should be exported to hooks for instance related opcodes.
if [ -z "$GANETI_INSTANCE_NAME" ]; then
  exit 0
fi

# This runs only for instance modification
reset_dns

# If GANETI_INSTANCE_NIC_COUNT is not set then nothing happens
FIRST=0
LAST=$((GANETI_INSTANCE_NIC_COUNT - 1))
for idx in $(seq $FIRST $LAST); do
  ip=GANETI_INSTANCE_NIC${idx}_IP
  mac=GANETI_INSTANCE_NIC${idx}_MAC
  mode=GANETI_INSTANCE_NIC${idx}_MODE
  link=GANETI_INSTANCE_NIC${idx}_LINK
  subnet=GANETI_INSTANCE_NIC${idx}_NETWORK_SUBNET
  subnet6=GANETI_INSTANCE_NIC${idx}_NETWORK_SUBNET6
  tags=GANETI_INSTANCE_NIC${idx}_NETWORK_TAGS
  eval IP=\$$ip
  eval MAC=\$$mac
  eval MODE=\$$mode
  eval LINK=\$$link
  eval SUBNET=\$$subnet
  eval SUBNET6=\$$subnet6
  eval TAGS=\$$tags

  for tag in $TAGS; do
    case $tag in
    $DNS_TAG)

      get_rev4_info "$IP"
      get_eui64 "$MAC" "$SUBNET6"
      get_rev6_info "$EUI64"
      hooks-log dnshook "update dns for $GANETI_INSTANCE_NAME $IP $EUI64"
      update_dns

      ;;
    esac

  done

done