always uses @ for subdomain when on root

.gitignore

@@ -1,2 +1,3 @@
 DIGITALOCEAN_TOKEN
 DIGITALOCEAN_DOMAIN
+REPEAT_CHECK_*

README.md

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+# digitalocean_dyndns
+
+Forked from [dc25/digitalocean_dyndns](https://github.com/dc25/digitalocean_dyndns).
+
+This script automatically keeps your DNS records for a HTTPS website working
+when you're hosting from a network with a dynamically allocated IP address, such
+as a typical home network.
+
+To use this script, first mark the shell files as runnable:
+
+```sh
+chmod +x ./dyndns.sh
+chmod +x ./get_ip_addr.sh
+```
+
+Then to set things up, first write your domain name, e.g. `example.com`, to
+`DIGITALOCEAN_DOMAIN`. Secondly, go to your DigitalOcean account and generate a
+Personal Access Token with scopes for creating, reading, and deleting domains.
+Write this to `DIGITALOCEAN_TOKEN`.
+
+The script should now run. Try it out:
+
+```sh
+./dyndns.sh 4 # for IPv$
+./dyndns.sh 6 # for IPv$
+```
+
+Go to the control panel in DigitalOcean for your domain, and check the A and
+AAAA records are what you expect. If they are, the next step is to get this
+script to run regularly.
+
+You could do this in a number of ways. Probably the easiest is with crontab.
+Run `crontab -e` to open your crontab for editing, and add these two lines:
+
+```cron
+* *  * * *   /home/.../dyndns.sh 4 > /tmp/dyndns.sh.4.log 2>&1
+* *  * * *   /home/.../dyndns.sh 6 > /tmp/dyndns.sh.6.log 2>&1
+```
+
+Wait one minute, and check the logs. If you want to see that it works, delete
+the REPEAT_CHECK_A and REPEAT_CHECK_AAAA files and wait for the script to run
+again. You may also want to have an MTA set up, as cron will try to send any
+unhandled output to your inbox.
+
+If you want to use this script for more than one domain, you can supply a domain
+name as a second argument. For example:
+
+```sh
+./dyndns.sh 4 example.com
+```

dyndns.bash

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-#! /bin/bash  
-
-# Work with DigitalOcean api to update "A" record for a domain.
-# Store DigitalOcean API token in file : DIGITALOCEAN_TOKEN 
-# Store domain to be updated in file : DIGITALOCEAN_DOMAIN 
-
-SCRIPT="${BASH_SOURCE[0]}"
-SCRIPT_DIR=$(builtin cd "${SCRIPT%/*}" && pwd )
-SCRIPT_NAME=${SCRIPT##*/}
-
-REPEAT_CHECK_DIR=$HOME/repeat_check
-REPEAT_CHECK=$REPEAT_CHECK_DIR/$SCRIPT_NAME # file to save argument in if successful
-
-DIGITALOCEAN_DOMAIN=`cat $SCRIPT_DIR/DIGITALOCEAN_DOMAIN`
-DIGITALOCEAN_TOKEN=`cat $SCRIPT_DIR/DIGITALOCEAN_TOKEN`
-
-# Get IP from command line if available.  Otherwise use curl to get public IP.
-IP=""
-if [ "$#" == "1" ]; then
-    IP=$1
-else
-    IP=`curl -4 icanhazip.com 2> /dev/null` 
-fi
-
-# If $IP does not look like a valid address then complain and exit.
-# For regular expression, thank you to : https://tecadmin.net/shell-script-validate-ipv4-addresses/
-if ! [[ $IP =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
-    echo Invalid IP address format: $IP
-    exit
-fi
-
-get_a_record_ids() {
-    curl -X GET \
-      -H "Content-Type: application/json" \
-      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
-      "https://api.digitalocean.com/v2/domains/$DIGITALOCEAN_DOMAIN/records" 2> /dev/null | jq '.domain_records |  map(select(.type == "A" and .name == "@")) | map(.id) | .[]'
-}
-
-add_a_record() {
-    curl -X POST \
-      -H "Content-Type: application/json" \
-      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
-      -d "{\"type\":\"A\"         \
-          ,\"name\":\"@\"         \
-          ,\"data\":\"$IP\"       \
-          ,\"priority\":null      \
-          ,\"port\":null          \
-          ,\"ttl\":1800           \
-          ,\"weight\":null        \
-          ,\"flags\":null         \
-          ,\"tag\":null           \
-          }"                      \
-      "https://api.digitalocean.com/v2/domains/$DIGITALOCEAN_DOMAIN/records" 2> /dev/null | jq '.domain_record.id'
-}
-
-delete_record_by_id() {
-    echo deleting existing A record for $DIGITALOCEAN_DOMAIN
-    curl -X DELETE \
-      -H "Content-Type: application/json" \
-      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
-      "https://api.digitalocean.com/v2/domains/$DIGITALOCEAN_DOMAIN/records/$1" > /dev/null 2>&1
-}
-
-replace_a_record() {
-    for id in `get_a_record_ids`; do
-        delete_record_by_id $id
-    done
-
-    new_record_id=`add_a_record`
-    if [ "$new_record_id" == "null" ] ; then
-        echo unable to add new A record for $DIGITALOCEAN_DOMAIN with value : $1
-        return 1
-    fi
-    echo added new A record for $DIGITALOCEAN_DOMAIN with value : $1
-}
-
-
-# exit if previous successful call was with same argument
-if [[ -e $REPEAT_CHECK ]]; then
-    PREVIOUS_IP=`cat $REPEAT_CHECK`
-    if [[ "$IP" ==  "$PREVIOUS_IP" ]]; then
-        echo previous update was also with argument: \"$IP\"  so exiting now to avoid duplicate work.
-        exit
-    fi
-fi
-
-# attempt to replace A record and, if successful, save arguments to check against next time
-if replace_a_record $IP; then
-    # if successful then save arguments.
-    echo update worked so saving arguments \"$IP\" in $REPEAT_CHECK
-    mkdir -p $REPEAT_CHECK_DIR
-    echo "$IP" > $REPEAT_CHECK
-fi

dyndns.sh

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+#!/bin/sh
+
+# Work with DigitalOcean api to update "A" and "AAAA" records for a domain.
+# Store DigitalOcean API token in file : DIGITALOCEAN_TOKEN 
+# Store domain to be updated in file : DIGITALOCEAN_DOMAIN 
+
+ip_version="$1"
+if [ -z "${ip_version:-}" ] || ([ "$ip_version" != 4 ] && [ "$ip_version" != 6 ]); then
+    echo "Error: no valid IP version provided" >&2
+    echo "Usage: dyndns.bash <4|6> [domain]" >&2
+    exit 1
+fi
+
+SCRIPT="$0"
+SCRIPT_DIR=$(cd "${SCRIPT%/*}" && pwd )
+SCRIPT_NAME=${SCRIPT##*/}
+CACHE_DIR=${CACHE_DIR:-~/.cache/dyndns}
+CONFIG_DIR=${CONFIG_DIR:-~/.config/dyndns}
+mkdir -p ${CACHE_DIR}
+mkdir -p ${CONFIG_DIR}
+
+IP="$($SCRIPT_DIR/get_ip_addr.sh $ip_version)"
+if [ -z "$IP" ]; then
+    echo "Error: could not find IP address" >&2
+    exit 1
+fi
+
+DIGITALOCEAN_TOKEN=`cat ${CONFIG_DIR}/DIGITALOCEAN_TOKEN`
+DOMAIN=${2:-`cat ${CONFIG_DIR}/DIGITALOCEAN_DOMAIN`}
+SUBDOMAIN=`echo $DOMAIN | sed "s/[^.]\+\.[^.]\+$//g"`
+if [ -z "$SUBDOMAIN" ]; then
+    SUBDOMAIN="@"
+    ROOT_DOMAIN=$DOMAIN
+elif [ "$SUBDOMAIN" = "@." ]; then
+    SUBDOMAIN="@"
+    ROOT_DOMAIN=`echo $DOMAIN | sed "s/^@.//"`
+else
+    SUBDOMAIN=`echo $SUBDOMAIN | sed "s/\.$//g"`
+    ROOT_DOMAIN=`echo $DOMAIN | sed "s/^${SUBDOMAIN}\.//g"`
+fi
+
+REPEAT_CHECK_DIR=${CACHE_DIR}
+REPEAT_CHECK_A=$REPEAT_CHECK_DIR/REPEAT_CHECK_${SUBDOMAIN}.${ROOT_DOMAIN}_A
+REPEAT_CHECK_AAAA=$REPEAT_CHECK_DIR/REPEAT_CHECK_${SUBDOMAIN}.${ROOT_DOMAIN}_AAAA
+REPEAT_CHECK="$([ $ip_version = 4 ] && echo $REPEAT_CHECK_A || echo $REPEAT_CHECK_AAAA)"
+
+get_a_record_ids() {
+    curl -X GET \
+      -H "Content-Type: application/json" \
+      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
+      "https://api.digitalocean.com/v2/domains/$ROOT_DOMAIN/records" 2> /dev/null | jq '.domain_records |  map(select(.type == "A" and .name == "$SUBDOMAIN")) | map(.id) | .[]'
+}
+
+get_aaaa_record_ids() {
+    curl -X GET \
+      -H "Content-Type: application/json" \
+      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
+      "https://api.digitalocean.com/v2/domains/$ROOT_DOMAIN/records" 2> /dev/null | jq '.domain_records |  map(select(.type == "AAAA" and .name == "$SUBDOMAIN")) | map(.id) | .[]'
+}
+
+add_a_record() {
+    curl -X POST \
+      -H "Content-Type: application/json" \
+      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
+      -d "{\"type\":\"A\"         \
+          ,\"name\":\"$SUBDOMAIN\"         \
+          ,\"data\":\"$IP\"       \
+          ,\"priority\":null      \
+          ,\"port\":null          \
+          ,\"ttl\":1800           \
+          ,\"weight\":null        \
+          ,\"flags\":null         \
+          ,\"tag\":null           \
+          }"                      \
+      "https://api.digitalocean.com/v2/domains/$ROOT_DOMAIN/records" 2> /dev/null | jq '.domain_record.id'
+}
+
+add_aaaa_record() {
+    curl -X POST \
+      -H "Content-Type: application/json" \
+      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
+      -d "{\"type\":\"AAAA\"         \
+          ,\"name\":\"$SUBDOMAIN\"         \
+          ,\"data\":\"$IP\"       \
+          ,\"priority\":null      \
+          ,\"port\":null          \
+          ,\"ttl\":1800           \
+          ,\"weight\":null        \
+          ,\"flags\":null         \
+          ,\"tag\":null           \
+          }"                      \
+      "https://api.digitalocean.com/v2/domains/$ROOT_DOMAIN/records" 2> /dev/null | jq '.domain_record.id'
+}
+
+delete_record_by_id() {
+    echo deleting existing A/AAAA record for ${SUBDOMAIN}.${ROOT_DOMAIN}
+    curl -X DELETE \
+      -H "Content-Type: application/json" \
+      -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
+      "https://api.digitalocean.com/v2/domains/$ROOT_DOMAIN/records/$1" > /dev/null 2>&1
+}
+
+replace_a_records() {
+    for id in `get_a_record_ids`; do
+        delete_record_by_id $id
+    done
+
+    new_record_id=`add_a_record`
+    if [ "$new_record_id" = "null" ] ; then
+        echo unable to add new A record for ${SUBDOMAIN}.${ROOT_DOMAIN} with value: $IP
+        return 1
+    fi
+    echo added new A record for ${SUBDOMAIN}.${ROOT_DOMAIN} with value: $IP
+}
+
+
+replace_aaaa_records() {
+    for id in `get_aaaa_record_ids`; do
+        delete_record_by_id $id
+    done
+
+    new_record_id=`add_aaaa_record`
+    if [ "$new_record_id" = "null" ] ; then
+        echo unable to add new AAAA record for ${SUBDOMAIN}.${ROOT_DOMAIN} with value: $IP
+        return 1
+    fi
+    echo added new AAAA record for ${SUBDOMAIN}.${ROOT_DOMAIN} with value: $IP
+}
+
+replace_records() {
+    [ $ip_version = 4 ] && replace_a_records || replace_aaaa_records
+}
+
+# exit if previous successful call was with same argument
+if [ -e $REPEAT_CHECK ]; then
+    PREVIOUS_IP=`cat $REPEAT_CHECK`
+    if [ "$IP" =  "$PREVIOUS_IP" ]; then
+        echo previous update was also with argument: \"$IP\"  so exiting now to avoid duplicate work.
+        exit
+    fi
+fi
+
+# attempt to replace records and, if successful, save arguments to check against next time
+if replace_records $IP; then
+    # if successful then save arguments.
+    echo update worked so saving arguments \"$IP\" in $REPEAT_CHECK
+    mkdir -p $REPEAT_CHECK_DIR
+    echo "$IP" > $REPEAT_CHECK
+fi

get_ip_addr.sh

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+#!/bin/sh
+
+ip_version="$1"
+if [ -z "${ip_version:-}" ] || ([ "$ip_version" != 4 ] && [ "$ip_version" != 6 ]); then
+    echo "Usage: get_ip_addr <4|6>" >&2
+    exit 1
+fi
+
+if [ $ip_version = 4 ]; then
+    dig +short myip.opendns.com @resolver1.opendns.com \
+        && exit 0 \
+        || exit 1
+fi
+
+set -eu
+CONN_NAME=${CONN_NAME:-nevis}
+CONN_DEVICE_NAME="${CONN_DEVICE_NAME:-$(nmcli --fields NAME,DEVICE con show | grep ^$CONN_NAME | sed 's/\s\+/ /g' | cut -d' ' -f 2)}"
+if [ -z "${CONN_DEVICE_NAME:-}" ]; then
+    echo "Could not find the connection device name for connection: \"$CONN_NAME\"" >&2
+    exit 1
+fi
+
+device_line_no="$(ip addr | grep -En ^[0-9]+:\ $CONN_DEVICE_NAME | cut -d':' -f 1)"
+if [ -z "${device_line_no:-}" ]; then
+    echo "Could not find device: \"$CONN_DEVICE_NAME\" in output of ip addr" >&2
+    exit 1
+fi
+
+ip_addr_output_for_device="$(ip addr | tail -n +$(($device_line_no + 1)))"
+
+device_no="$(ip addr | tail -n +$device_line_no | head -n 1 | cut -d':' -f 1)"
+next_device_no=$(($device_no + 1))
+next_device_line_no="$(ip addr | grep -En ^${next_device_no}:\ | cut -d':' -f 1)"
+if [ -n "${next_device_line_no:-}" ]; then
+    len=$(($next_device_line_no - ($device_line_no + 1)))
+    ip_addr_output_for_device="$(echo $ip_addr_output_for_device | head -n $len)"
+fi
+
+ipv4_regex="([a-z0-9]{1,3}\.){3}[a-z0-9]{1,3}"
+ipv6_regex="([a-z0-9]{1,4}:){7}[a-z0-9]{1,4}"
+if [ "$ip_version" = "4" ]; then
+    ip_regex="$ipv4_regex"
+else
+    ip_regex="$ipv6_regex"
+fi
+ip="$(echo "$ip_addr_output_for_device" | grep "scope global" | grep -oE $ip_regex | head -n 1)"
+if [ -z "${ip:-}" ]; then
+    echo "Could not find global IP in output of ip addr under device: $CONN_DEVICE_NAME ($CONN_NAME)"
+    exit 1
+fi
+
+echo "$ip"