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hetzner_ddns.sh
executable file
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hetzner_ddns.sh
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#!/bin/sh
self='hetzner_ddns'
version='0.2.5'
daemon=0
for arg in $(seq "$#"); do
param="$(eval "echo \$$arg")"
case "$param" in
'--daemon'|'-d')
daemon=1;;
'--version'|'-v')
printf '%s %s\n' "$self" "$version"
exit 0;;
'--help'|'-h')
man hetzner_ddns;
exit 0;;
*)
self="${self}.$param";;
esac
done
# Check dependencies
if ! command -v curl > /dev/null || \
! command -v awk > /dev/null || \
! command -v jq > /dev/null
then
>&2 echo 'Error: missing dependency'
exit 1
fi
# Check logging support
if ! touch "/var/log/$self.log";
then
>&2 echo "Error: unable to open log file /var/log/$self.log"
exit 2
fi
read_configuration() {
# Read variabels from configuration file
if test -r "/usr/local/etc/$self.conf"; then
printf '[%s] Reading configuration from %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "/usr/local/etc/$self.conf" \
| tee -a "/var/log/$self.log"
# shellcheck disable=SC1090
. "/usr/local/etc/$self.conf"
records_escaped="$(echo "$records" | sed 's:\*:\\\*:g')"
else
printf '[%s] Error: unable to read configuration file %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "/usr/local/etc/$self.conf" | tee -a "/var/log/$self.log"
>&2 echo "Error: unable to read configuration file /usr/local/etc/$self.conf"
exit 78
fi
# Check configuration
if [ -z "$interval" ]; then
printf '[%s] Warning: interval is not set, defaulting to 60 seconds\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
interval=60
fi
if [ -z "$key" ]; then
printf '[%s] Error: API key is not set, unable to proceed\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
exit 78
fi
if [ -z "$domain" ]; then
printf '[%s] Error: Domain is not set, unable to proceed\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
exit 78
fi
if [ -z "$records" ]; then
printf '[%s] Warning: Records are not set, exiting cleanly\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
exit 0
fi
}
test_api_key() {
# Test API key validity
if curl "https://dns.hetzner.com/api/v1/zones" \
-H "Auth-API-Token: $key" 2>/dev/null | \
grep -q 'Invalid authentication credentials'; then
printf '[%s] Error: Invalid API key\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
exit 22
fi
}
get_zone() {
# Get zone ID
zone="$(
curl "https://dns.hetzner.com/api/v1/zones" \
-H "Auth-API-Token: $key" 2>/dev/null | \
jq -r '.zones[] | .name + " " + .id' | \
awk -v d="$domain" '$1==d {print $2}'
)"
if [ -z "$zone" ]; then
printf '[%s] Error: Unable to fetch zone ID for domain %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "$domain" | tee -a "/var/log/$self.log"
return 1
else
printf '[%s] Zone for %s: %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" \
"$domain" "$zone" | tee -a "/var/log/$self.log"
return 0
fi
}
get_record() {
# Get record IDs
if [ -n "$zone" ]; then
record_ipv4="$(
echo "$records_json" | \
jq -r '.records[] | .name + " " + .type + " " + .id' | \
awk -v r="$1" -v d="$domain" \
'($1==r || $1==sprintf("%s.%s",r,d)) && $2=="A" {print $3 }'
)"
record_ipv6="$(
echo "$records_json" | \
jq -r '.records[] | .name + " " + .type + " " + .id' | \
awk -v r="$1" -v d="$domain" \
'($1==r || $1==sprintf("%s.%s",r,d)) && $2=="AAAA" {print $3 }'
)"
fi
if [ -z "$record_ipv4" ] && [ -z "$record_ipv6" ]; then
return 1
else
printf '[%s] IPv4 record for %s: %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$1.$domain" \
"${record_ipv4:-(missing)}" | tee -a "/var/log/$self.log"
printf '[%s] IPv6 record for %s: %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$1.$domain" \
"${record_ipv6:-(missing)}" | tee -a "/var/log/$self.log"
return 0
fi
}
get_records() {
# Get all record IDs
records_json="$(
curl "https://dns.hetzner.com/api/v1/records?zone_id=$zone" \
-H "Auth-API-Token: $key" 2>/dev/null
)"
for current_record in $records_escaped; do
current_record="$(echo "$current_record" | sed 's:\\::')"
if get_record "$current_record"; then
records_ipv4="$records_ipv4$current_record=$record_ipv4 "
records_ipv6="$records_ipv6$current_record=$record_ipv6 "
else
printf '[%s] Warning: Missing both A and AAAA records for %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "$current_record.$domain" | tee -a "/var/log/$self.log"
fi
done
if [ -z "$records_ipv4" ] && [ -z "$records_ipv6" ]; then
printf '[%s] Error: No applicable records found %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "$domain" | tee -a "/var/log/$self.log"
return 1
fi
}
get_record_ip_addr() {
# Get record's IP address
if [ -n "$record_ipv4" ]; then
ipv4_rec="$(
curl "https://dns.hetzner.com/api/v1/records/$record_ipv4" \
-H "Auth-API-Token: $key" 2>/dev/null | \
jq -r '.record.value'
)"
fi
if [ -n "$record_ipv6" ]; then
ipv6_rec="$(
curl "https://dns.hetzner.com/api/v1/records/$record_ipv6" \
-H "Auth-API-Token: $key" 2>/dev/null | \
jq -r '.record.value'
)"
fi
if [ -n "$record_ipv4" ]; then
if [ -z "$ipv4_rec" ] || [ "$ipv4_rec" = 'null' ]; then
printf '[%s] Warning: Unable to fetch previous IPv4 address for %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "$current_record.$domain" | tee -a "/var/log/$self.log"
ipv4_rec=''
fi;
fi
if [ -n "$record_ipv6" ]; then
if [ -z "$ipv6_rec" ] || [ "$ipv6_rec" = 'null' ]; then
printf '[%s] Warning: Unable to fetch previous IPv6 address for %s\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" "$current_record.$domain" | tee -a "/var/log/$self.log"
ipv6_rec=''
fi;
fi
if [ -z "$ipv4_rec" ] && [ -z "$ipv6_rec" ]; then
return 1
fi
}
get_my_ip_addr() {
# Get current public IP address
ipv4_cur="$(
curl -4 'https://ip.hetzner.com/' 2>/dev/null
)"
ipv6_cur="$(
curl -6 'https://ip.hetzner.com/' 2>/dev/null | sed 's/:$/:1/g'
)"
if [ -z "$ipv4_cur" ] && [ -z "$ipv6_cur" ]; then
printf '[%s] Error: Unable to fetch current self IP address\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
return 1
fi
}
set_record() {
# Update record if IP address has changed
if [ -n "$record_ipv4" ] && [ -n "$ipv4_cur" ] && [ "$ipv4_cur" != "$ipv4_rec" ]; then
curl -X "PUT" "https://dns.hetzner.com/api/v1/records/$record_ipv4" \
-H 'Content-Type: application/json' \
-H "Auth-API-Token: $key" \
-d "{
\"value\": \"$ipv4_cur\",
\"ttl\": $interval,
\"type\": \"A\",
\"name\": \"$current_record\",
\"zone_id\": \"$zone\"
}" 1>/dev/null 2>/dev/null &&
printf "[%s] Update IPv4 for %s: %s => %s\n" "$(date '+%Y-%m-%d %H:%M:%S')" \
"$current_record.$domain" "$ipv4_rec" "$ipv4_cur" | tee -a "/var/log/$self.log"
fi
if [ -n "$record_ipv6" ] && [ -n "$ipv6_cur" ] && [ "$ipv6_cur" != "$ipv6_rec" ]; then
curl -X "PUT" "https://dns.hetzner.com/api/v1/records/$record_ipv6" \
-H 'Content-Type: application/json' \
-H "Auth-API-Token: $key" \
-d "{
\"value\": \"$ipv6_cur\",
\"ttl\": $interval,
\"type\": \"AAAA\",
\"name\": \"$current_record\",
\"zone_id\": \"$zone\"
}" 1>/dev/null 2>/dev/null &&
printf "[%s] Update IPv6 for %s: %s => %s\n" "$(date '+%Y-%m-%d %H:%M:%S')" \
"$current_record.$domain" "$ipv6_rec" "$ipv6_cur" | tee -a "/var/log/$self.log"
fi
}
pick_record() {
# Get record ID from array
echo "$2" | \
awk "{
for(i=1;i<=NF;i++){
n=\$i;gsub(/=.*/,\"\",n);
r=\$i;gsub(/.*=/,\"\",r);
if(n==\"$1\"){
print r;break
}
}}"
}
set_records() {
# Get my public IP address
if get_my_ip_addr; then
# Update all records if possible
for current_record in $records_escaped; do
current_record="$(echo "$current_record" | sed 's:\\::')"
record_ipv4="$(pick_record "$current_record" "$records_ipv4")"
record_ipv6="$(pick_record "$current_record" "$records_ipv6")"
if [ -n "$record_ipv4" ] || [ -n "$record_ipv6" ]; then
get_record_ip_addr && set_record
fi
done
fi
}
run_ddns() {
printf '[%s] Started Hetzner DDNS daemon\n' "$(date '+%Y-%m-%d %H:%M:%S')" \
| tee -a "/var/log/$self.log"
read_configuration
test_api_key
while ! get_zone || ! get_records; do
sleep $((interval/2+1))
printf '[%s] Retrying to fetch zone and record data\n' "$(date '+%Y-%m-%d %H:%M:%S')" \
| tee -a "/var/log/$self.log"
done
printf '[%s] Configuration successful\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
printf '[%s] Watching for IP address and record changes\n' \
"$(date '+%Y-%m-%d %H:%M:%S')" | tee -a "/var/log/$self.log"
while true; do
set_records
sleep "$interval"
done
}
if [ "$daemon" = '1' ]; then
# Deamonize and write PID to file
if touch "/var/run/$self.pid";
then
run_ddns &
echo $! > "/var/run/$self.pid"
else
>&2 echo 'unable to daemonize'
exit 2
fi
else
# Run in foreground
run_ddns
fi