rt3x.de NoPaste

#!/usr/bin/env zsh
# 
# dns-update.sh
#     Dynamic DNS update script made for ServerCow DNS.
# 
# Requirements:
#  - zsh
#  - curl
#  - iproute2
#  - dig
# 

SCRIPT_NAME="dns-update.sh"
SCRIPT_VERSION="0.20250106.1"
CONFIGFILE="$HOME/.config/dns-update-sh"



################################################################
# From _base.inc.sh
# 

#source ~malte70/bin/_base.inc.sh

# Write to stdout and support escape-codes
_print() {
	echo -en "$@"
}
# Like _print, but add a newline
_println() {
	echo -e "$@"
}
# Write only to a real terminal
_print_term() {
	[[ $TERM != "dump" ]] && _print "$@"
}
# _print_term with a leading newline
_println_term() {
	[[ $TERM != "dump" ]] && _println "$@"
}
# A regular message
message() {
	_print_term $_ANSI_COLOR_GREEN
	_print "[${SCRIPT_NAME}] "
	_print_term $_ANSI_RESET
	_println "$@"
}
# An error message (on stderr)
message_error() {
	(
		_print_term $_ANSI_COLOR_RED
		_print "[${SCRIPT_NAME}] [ERROR] "
		_print_term $_ANSI_RESET
		_println "$@"
	) >&2
}
# A message with additional information (INFO level, on stderr)
message_info() {
	(
		_print_term $_ANSI_COLOR_YELLOW
		_print "[${SCRIPT_NAME}] [INFO]  "
		_print_term $_ANSI_RESET
		_println "$@"
	) >&2
}
version() {
	echo "$SCRIPT_NAME $SCRIPT_VERSION"
}



################################################################
# Be quiet when executed as cronjob
# 

if [[ "$RUN_CONTEXT" == "crontab" ]]; then
	_print_term(){}
	message_info(){}
fi



################################################################
# Command line options
# 

usage() {
	echo "Usage:"
	echo "   $SCRIPT_NAME [OPTIONS]"
	echo 
	echo "Options:"
	echo "  --version -V  Show the version and exit"
	echo "  --help    -h  Show this help and exit"
	echo "  --dry-run -d  Check for changes, but di not modify DNS records"
	echo 
}

DO_DRY_RUN="false"
while [[ $# -gt 0 ]]; do
	if [[ "$1" == "--help" || "$1" == "-h" ]]; then
		version
		echo
		usage
		exit 0

	elif [[ "$1" == "--version" || "$1" == "-V" ]]; then
		version
		exit 0

	elif [[ "$1" == "--dry-run" || "$1" == "-d" ]]; then
		DO_DRY_RUN="true"

	elif [[ "${1:0:1}" == "-" ]]; then
		message_error "Unknown option: \"$1\""
		exit 2
		
	else
		usage >&2
		exit 2
		
	fi
	
	shift
done



################################################################
# Configuration
# 

if [[ ! -f "${CONFIGFILE}" ]]; then
	message_error "Config file ${CONFIGFILE} does not exist\!" >&2
	message_info "Creating a new file using empty default values."
	echo '# 
# ~/.config/dns-update-sh
# 
#     Config file for /usr/local/sbin/dns-update.sh
# 

# ServerCow DNS API user name
DNS_API_USERNAME=""

# ServerCow DNS API password
DNS_API_PASSWORD=""

# healthchecks.io Ping URL
# Dkipped if this is set to an empty string.
#HEALTHCHECKS_PING_URL="https://healthchecks.example.com/ping/XXXXXXXXXXXXXXXXXXXXXX/dns-update"
HEALTHCHECKS_PING_URL=""

# List of domains to update
DNS_DOMAINS=(
	"example.com"
)
' > "${CONFIGFILE}"
	exit 1

else
	source "${CONFIGFILE}"
fi

if [[ -z $DNS_API_URL_TEMPLATE ]]; then
	# Default DNS API URL for ServerCow
	DNS_API_URL_TEMPLATE="https://www.servercow.de/dnsupdate/update.php?username=${DNS_API_USERNAME}&pass=${DNS_API_PASSWORD}&hostname=%DOMAIN%&ipaddr=%IP%"
fi



################################################################
# Helper funtions
# 

get_ipv4() {
	# Get external IPv4 address
	curl -s "http://ipinfo.io/ip"
}

get_ipv6() {
	# Get IPv6 address
	
	if [[ "$1" == "--with-privacy" ]]; then
		# Returns IPv6 with privacy extensions
		ipv6=$(curl -s -6 "https://ifconfig.co")
	else
		# Returns IPv6 WITHOUT privacy extensions
		ipv6=$(ip addr show eth0 | grep inet6\ 2001 | grep -v :: | cut -d" " -f6 | cut -d/ -f1)
	fi
	echo "$ipv6"
}



################################################################
# Configuration
# 

update_ipv4() {
	# Get current external IP
	MY_IP=$(get_ipv4)
	
	if [[ -z $MY_IP ]]; then
		message_error 'Could not get external IP!'
		exit 1
	fi
	if [[ $MY_IP == $(dig +short ${DNS_DOMAINS[1]}) ]]; then
		message_info "IPv4 not changed"
		return 0
	fi
	
	if [[ $MY_IP != $(dig +short ${DNS_DOMAINS[1]}) ]]; then
		DNS_API_URL=${DNS_API_URL_TEMPLATE:gs/%IP%/$MY_IP}
		
		
		num_failed_ipv4=0
		
		for domain in "${DNS_DOMAINS[@]}"; do
			myurl=${DNS_API_URL:gs/%DOMAIN%/$domain/}
			
			message_info "Updating DNS record for $domain"
			if [[ "$DO_DRY_RUN" == "true" ]]; then
				message_info "API call using curl: curl -s \"$myurl\""
			else
				curl -s "$myurl" --output /dev/null
				
				if [[ $? -ne 0 ]]; then
					message_error "curl returned an error for \"$myurl\""
					num_failed_ipv4=$((num_failed_ipv4 + 1))
				fi
			fi
		done
		
		
		if [[ $num_failed_ipv4 -gt 0 ]]; then
			message_info "Note: From a total number of ${#DNS_DOMAIN[@]} API calls $num_failed_ipv4 failed for IPv4."
		fi
		
	fi
}


update_ipv6() {
	# Returns IPv6 with privacy extensions
	#MY_IP6=$(get_ipv6 --with-privacy)
	# Returns IPv6 WITHOUT privacy extensions
	MY_IP6=$(get_ipv6)
	
	if ! [[ -z $MY_IP ]]; then
		if [[ $MY_IP == $(dig +short ${DNS_DOMAINS[1]} AAAA) ]]; then
			message_info "IPv6 not changed"
			return 0
		fi
		
		#DNS_API_URL_TEMPLATE=${DNS_API_URL_TEMPLATE:gs/$MY_IP/$MY_IP6}
		DNS_API_URL=${DNS_API_URL_TEMPLATE:gs/%IP%/$MY_IP6}
		
		
		num_failed_ipv6=0
		
		for domain in "${DNS_DOMAINS[@]}"; do
			myurl=${DNS_API_URL:gs/%DOMAIN%/$domain/}
			
			message_info "Updating DNS record for $domain"
			if [[ "$DO_DRY_RUN" == "true" ]]; then
				message_info "API call using curl: curl -s \"$myurl\""
			else
				curl -s "$myurl" --output /dev/null
				
				if [[ $? -ne 0 ]]; then
					message_error "curl returned an error for \"$myurl\""
					num_failed_ipv6=$((num_failed_ipv6 + 1))
				fi
			fi
		done
		
	fi
}


update_ipv4
update_ipv6

# Calculate failure statistics
num_failed=$((num_failed_ipv4 + num_failed_ipv6))



# Notify healthchecks.io
# See also: https://healthchecks.rt3x.de/docs/signaling_failures/
if [[ -n $HEALTHCHECKS_PING_URL ]]; then
	curl \
		-s \
		"${HEALTHCHECKS_PING_URL}/${num_failed}" \
		--output /dev/null
fi