Update domain expiry plugin to use RDAP too, not just whois.

domains/local/lib/python3/cmk_addons/plugins/domains/libexec/agent_domains_expiry

@@ -1,7 +1,7 @@
 #!/bin/bash
 # Copyright (C) 2025 Spearhead Systems SRL
 
-set -eu
+set -euo pipefail
 
 if [[ $# < 3 ]]; then
     echo "Usage:   ${@: 0:1} <domains> <crit date> <warn date>" 1>&2
@@ -14,15 +14,58 @@ domains="${@: 1:$#-2}"
 warn="${@: -1:1}"
 crit="${@: -2:1}"
 
+
+# Attempt lookup of domain name expiration using whois.
+#
+# Unfortunately, there's no actual format for whois entries, so this is a
+# best-effort based on things seen in the wild. Note that ccTLDs usually do not
+# publish expiry dates at all.
+whois_domain() {
+    whois "$1" | grep 'Expir.*' | head -1 | grep -Eo '[0-9]{4}-[0-9]{2}-[0-9]{2}'
+}
+
+# Attempt lookup of domain name expiration using RDAP.
+#
+# Unfortunately, RDAP tools are still relatively new and not available in many
+# repos, so we do the lookup manually using curl. There's a two-step process:
+#
+# * look up (and cache) dns info from IANA.
+# * using the info from IANA, query the TLD for the domain
+#
+# Also, as of 2025, RDAP is useful with gTLDs and about 1/3rd of ccTLDs.
+rdap_domain() {
+    dns_file="$HOME/tmp/agent_domains_expiry.json"
+    domain="$1"
+    tld="${domain##*.}"   # get TLD off end of $domain
+
+    # Only attempt to fetch the file if it's older than 24h (or doesn't exist)
+    if [[ ! -f "$dns_file" ]] || [[ -n $(find "$dns_file" -mtime +0 2>/dev/null) ]]; then
+      # We do an conditional GET, using the file's timestamp
+      curl --silent \
+           --time-cond "$dns_file" \
+           --output "$dns_file"    \
+           "https://data.iana.org/rdap/dns.json"
+    fi
+
+    registrar=$(jq -r '.services[] | select(.[0][] == "'"$tld"'") | .[1][0]' "$dns_file" 2> /dev/null)
+
+    if [[ "$registrar" != "" ]]; then
+        curl -s "${registrar}domain/${domain}" |
+            jq -r '.events[] | select(.eventAction == "expiration") | .eventDate' 2> /dev/null |
+            grep -Eo '[0-9]{4}-[0-9]{2}-[0-9]{2}'
+    fi
+}
+
+
 echo "<<<domains_expiry:sep(0)>>>"
 
 for domain in $domains; do
-    echo -n "{\"domain\": \"$domain\", \"state\": \""
+    expires=$(rdap_domain "$domain" || true)
+    if [[ "$expires" == "" ]]; then
+        expires=$(whois_domain "$domain" || true)
+    fi
 
-    # Unfortunately, there's no actual format for whois entries, so this is a
-    # best-effort based on things seen in the wild. Note that ccTLDs usually
-    # do not publish expiry dates at all.
-    expires=$(whois "$domain" | grep 'Expir.*' | head -1 | grep -Eo '[0-9]{4}-[0-9]{2}-[0-9]{2}' || true)
+    echo -n "{\"domain\": \"$domain\", \"state\": \""
 
     if [[ "$expires" == "" ]]; then
         echo -n "UNKNOWN"
@@ -34,9 +77,8 @@ for domain in $domains; do
         echo -n "OK"
     fi
 
-    if [[ "$expires" == "" ]]; then
-        echo "\"}"
-    else
-        echo "\", \"expires\": \"$expires\"}"
+    if [[ "$expires" != "" ]]; then
+        echo -n "\", \"expires\": \"$expires"
     fi
+    echo "\"}"
 done