pdns_pipe.sh

#!/usr/bin/env bash
#
# Originally written by Sam Stephenson for xip.io
set -e
shopt -s nocasematch

# Configuration
#
# Increment this timestamp when the contents of the file change.
XIP_TIMESTAMP="2018092000"

# The top-level domain for which the name server is authoritative.
# CHANGEME: change "sslip.io" to your domain
XIP_DOMAIN="sslip.io"

# How long responses should be cached, in seconds.
XIP_TTL=300

# SOA record
XIP_SOA="briancunnie.gmail.com ns-he.nono.io $XIP_TIMESTAMP $XIP_TTL $XIP_TTL $XIP_TTL $XIP_TTL"

# The public IP addresses (e.g. for the web site) of the top-level domain.
# `A` queries for the top-level domain will return this list of addresses.
# CHANGEME: change this to your domain's webserver's address
XIP_ROOT_ADDRESSES=( "78.46.204.247" )
XIP_ROOT_ADDRESSES_AAAA=( "2a01:4f8:c17:b8f::2" )

# The public IP addresses on which this xip-pdns server will run.
# `NS` queries for the top-level domain will return this list of servers.
# Note: [change from xip.io] The NS servers are in a different domain
# (i.e. nono.io) so the addresses don't need to be included.
XIP_NS=(           "ns-aws.nono.io" "ns-azure.nono.io" "ns-gce.nono.io" "ns-vultr.nono.io" )

# These are the MX records for your domain.  IF YOU'RE NOT SURE,
# don't set it at at all (comment it out)--it defaults to no
# MX records.
# XIP_MX_RECORDS=(
#   "10"  "mx.zoho.com"
#   "20"  "mx2.zoho.com"
# )
XIP_MX_RECORDS=(
  "10"	"mail.protonmail.ch"
)

# These are the TXT records for your domain.  IF YOU'RE NOT SURE,
# don't set it at at all (comment it out)--it defaults to no
XIP_TXT_RECORDS=(
  "protonmail-verification=ce0ca3f5010aa7a2cf8bcc693778338ffde73e26"
)

# These are the domains which we should not reply with any records
# at all. Normally this can be emtpy. The only purpose this variable
# serves is in the case of multiple PowerDNS backends, in this case
# the BIND backend. It shouldn't return any records for these domains,
# otherwise it can break CNAME/wildcard records for which the BIND
# backend is authoritative.
XIP_EXCLUDED_DOMAINS=(
  "nono.io"
  "nono.com"
)

if [ -a "$1" ]; then
  source "$1"
fi

#
# Protocol helpers
#
read_cmd() {
  local IFS=$'\t'
  local i=0
  local arg

  read -ra CMD
  for arg; do
    eval "$arg=\"\${CMD[$i]}\""
    let i=i+1
  done
}

send_cmd() {
  local IFS=$'\t'
  printf "%s\n" "$*"
}

fail() {
  send_cmd "FAIL"
  log "Exiting"
  exit 1
}

read_helo() {
  read_cmd HELO VERSION
  [ "$HELO" = "HELO" ] && [ "$VERSION" = "1" ]
}

read_query() {
  read_cmd TYPE QNAME QCLASS QTYPE ID IP
}

send_answer() {
  local type="$1"
  shift
  send_cmd "DATA" "$QNAME" "$QCLASS" "$type" "$XIP_TTL" "$ID" "$@"
}

log() {
  printf "[xip-pdns:$$] %s\n" "$@" >&2
}


#
# xip.io domain helpers
#
IP_PATTERN="(^|\.)(x{0}(x{0}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))($|\.)"
DASHED_IP_PATTERN="(^|-|\.)(x{0}(x{0}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)-){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))($|-|\.)"
# https://stackoverflow.com/questions/53497/regular-expression-that-matches-valid-ipv6-addresses
# We don't use "dotted" IPv6 because DNS doesn't allow two dots next to each other
#   e.g. "::1" -> "1..sslip.io" isn't allowed (dig error: `is not a legal name (empty label)`)
DASHED_IPV6_PATTERN="(^|\.)(x{0}([0-9a-fA-F]{1,4}-){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}-){1,7}-|([0-9a-fA-F]{1,4}-){1,6}-[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}-){1,5}(-[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}-){1,4}(-[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}-){1,3}(-[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}-){1,2}(-[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}-(x{0}(-[0-9a-fA-F]{1,4}){1,6})|-(x{0}(-[0-9a-fA-F]{1,4}){1,7}|-))(\.|$)"

qtype_is() {
  [ "$QTYPE" = "$1" ] || [ "$QTYPE" = "ANY" ]
}

qname_is_root_domain() {
  [ "$QNAME" = "$XIP_DOMAIN" ]
}

subdomain_is_ip() {
  [[ "$QNAME" =~ $IP_PATTERN ]]
}

subdomain_is_dashed_ip() {
  [[ "$QNAME" =~ $DASHED_IP_PATTERN ]]
}

subdomain_is_dashed_ipv6() {
  [[ "$QNAME" =~ $DASHED_IPV6_PATTERN ]]
}

resolve_ip_subdomain() {
  [[ "$QNAME" =~ $IP_PATTERN ]] || true
  echo "${BASH_REMATCH[2]}"
}

resolve_dashed_ip_subdomain() {
  [[ "$QNAME" =~ $DASHED_IP_PATTERN ]] || true
  echo "${BASH_REMATCH[2]//-/.}"
}

resolve_dashed_ipv6_subdomain() {
  [[ "$QNAME" =~ $DASHED_IPV6_PATTERN ]] || true
  echo "${BASH_REMATCH[2]//-/:}"
}

answer_soa_query() {
  send_answer "SOA" "$XIP_SOA"
}

answer_ns_query() {
  local i=1
  local ns_address
  for ns in "${XIP_NS[@]}"; do
    send_answer "NS" "$ns"
  done
}

answer_root_a_query() {
  local address
  for address in "${XIP_ROOT_ADDRESSES[@]}"; do
    send_answer "A" "$address"
  done
}

answer_root_aaaa_query() {
  local address
  for address in "${XIP_ROOT_ADDRESSES_AAAA[@]}"; do
    send_answer "AAAA" "$address"
  done
}

answer_localhost_a_query() {
  send_answer "A" "127.0.0.1"
}

answer_localhost_aaaa_query() {
  send_answer "AAAA" "::1"
}

answer_mx_query() {
  set -- "${XIP_MX_RECORDS[@]}"
  while [ $# -gt 1 ]; do
    send_answer "MX" "$1	$2"
  shift 2
  done
}

answer_txt_query() {
  local address
  for text in "${XIP_TXT_RECORDS[@]}"; do
    send_answer "TXT" "$text"
  done
}

answer_subdomain_a_query_for() {
  local type="$1"
  local address="$(resolve_${type}_subdomain)"
  if [ -n "$address" ]; then
    send_answer "A" "$address"
  fi
}

answer_subdomain_aaaa_query_for() {
  local type="$1"
  local address="$(resolve_${type}_subdomain)"
  if [ -n "$address" ]; then
    send_answer "AAAA" "$address"
  fi
}


#
# PowerDNS pipe backend implementation
#
trap fail err
read_helo
send_cmd "OK" "xip.io PowerDNS pipe backend (protocol version 1)"

while read_query; do
  log "Query: type=$TYPE qname=$QNAME qclass=$QCLASS qtype=$QTYPE id=$ID ip=$IP"

  for excluded_domain in "${XIP_EXCLUDED_DOMAINS[@]}"; do
    if [[ $QNAME =~ $excluded_domain$ ]]; then
      log "'$QNAME' matched '$excluded_domain'"
      send_cmd "END"
      continue 2
    fi
  done

  if qtype_is "SOA"; then
    answer_soa_query
  fi
  if qtype_is "NS"; then
    answer_ns_query
  fi
  if qtype_is "TXT"; then
    answer_txt_query
  fi
  if qtype_is "MX"; then
    answer_mx_query
  fi
  if qtype_is "A"; then
    LC_QNAME=$(echo $QNAME | tr 'A-Z' 'a-z')
    if [ $LC_QNAME == $XIP_DOMAIN ]; then
      answer_root_a_query
    else
      if [ $LC_QNAME == "localhost.$XIP_DOMAIN" ]; then
        answer_localhost_a_query
      elif subdomain_is_dashed_ip; then
        answer_subdomain_a_query_for dashed_ip
      elif subdomain_is_ip; then
        answer_subdomain_a_query_for ip
      fi
    fi
  fi

  if qtype_is "AAAA"; then
    LC_QNAME=$(echo $QNAME | tr 'A-Z' 'a-z')
    if [ $LC_QNAME == $XIP_DOMAIN ]; then
      answer_root_aaaa_query
    elif [ $LC_QNAME == "localhost.$XIP_DOMAIN" ]; then
        answer_localhost_aaaa_query
    elif subdomain_is_dashed_ipv6; then
        answer_subdomain_aaaa_query_for dashed_ipv6
    fi
  fi

  send_cmd "END"
done