update-plex-ipv6-access-url.sh

#!/bin/bash
# Retrieve host IPv6 address and update Plex custom access url accordingly
# based on workaround posted by Pikey18 on the Plex subreddit: https://www.reddit.com/r/PleX/comments/b82opu/plex_remote_access_over_ipv6/

# IPv6 address expansion (https://stackoverflow.com/a/50208987)
# helper to convert hex to dec (portable version)
hex2dec(){
    [ "$1" != "" ] && printf "%d" "$(( 0x$1 ))"
}

# expand an ipv6 address
expand_ipv6() {
    ip=$1

    # prepend 0 if we start with :
    echo $ip | grep -qs "^:" && ip="0${ip}"

    # expand ::
    if echo $ip | grep -qs "::"; then
        colons=$(echo $ip | sed 's/[^:]//g')
        missing=$(echo ":::::::::" | sed "s/$colons//")
        expanded=$(echo $missing | sed 's/:/:0/g')
        ip=$(echo $ip | sed "s/::/$expanded/")
    fi

    blocks=$(echo $ip | grep -o "[0-9a-f]\+")
    set $blocks

    printf "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n" \
        $(hex2dec $1) \
        $(hex2dec $2) \
        $(hex2dec $3) \
        $(hex2dec $4) \
        $(hex2dec $5) \
        $(hex2dec $6) \
        $(hex2dec $7) \
        $(hex2dec $8)
}

# Get IPv6 address of given interface (command adapted from: https://superuser.com/a/1057290)
IPv6=`/sbin/ip -6 -o addr show dev "$1" scope global | grep inet6 | grep -v deprecated | grep -v temporary | awk -F '[ \t]+|/' '{print $4}'`
if [ -n "$IPv6" ]; then
	echo "Got IPv6 address: $IPv6"
	# Format IPv6 for Plex (replace : with -)
	PlexFormatIPv6=`expand_ipv6 "$IPv6" | sed -e "s/:/-/g"`
	if ! grep -q "customConnections\=\"https\:\/\/$PlexFormatIPv6" "$2" ; then
		echo "Current IPv6 does not match config, updating config"
		# Replace old IPv6 with new one
		sed -i -e "s/customConnections\=\"https\:\/\/[a-fA-F0-9\-]*/customConnections\=\"https:\/\/$PlexFormatIPv6/" "$2"
		# Restart Plex service, uncomment line for your server's os or add your own
		# systemctl restart plexmediaserver # systemd Linux distributions (Ubuntu, Debian, ...)
		# synoservice --restart pkgctl-Plex\ Media\ Server # Synology DiskStations (details: https://tech.setepontos.com/2018/03/25/control-synology-dsm-services-via-terminal-ssh/)
		# synopkg start PlexMediaServer # Synology NAS DSM 7 with the official package
	else
		echo "Current IPv6 matches config, exiting"
	fi
	exit 0
else
	echo "No IPv6 address found, exiting"
	exit 1
fi