vulkoingim · May 24, 2018 10:11 · May 24, 2018
diff --git a/gcp_ips.sh b/gcp_ips.sh
@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+# This script lists all ip ranges currently used by
+# the google cloud platform, according to ns-lookup / dig
+# TXT _cloud-netblocks.googleusercontent.com
+#
+# https://cloud.google.com/compute/docs/faq#ipranges
+
+errcho() {
+    >&2 echo "$@"
+}
+
+_fmt() {
+    echo "$1" | cut -f "$2" -d':'
+}
+
+_txt_recursive() {
+    for txt_entry in $(dig txt "$1" +short | tr " " "\n"); do
+        if [[ "${txt_entry}" == include:* ]]; then
+            _txt_recursive "$(_fmt ${txt_entry} 2)"
+        elif [[ "${txt_entry}" == ip4:* && "${ipv4}" == true ]]; then
+            _fmt "${txt_entry}" 2
+        elif [[ "${txt_entry}" == ip6:* && "${ipv6}" == true ]]; then
+            _fmt "${txt_entry}" 2-9
+        fi
+    done
+}
+
+domain="_cloud-netblocks.googleusercontent.com"
+
+ipv4=true
+ipv6=true
+
+while (( $# > 0 )); do
+    case "$1" in
+        --ipv4)
+            ipv6=false
+            shift 1
+            ;;
+        --ipv6)
+            ipv4=false
+            shift 1
+            ;;
+        --domain)
+            domain="$2"
+            shift 2
+            ;;
+        *)
+            errcho "Unknown option $1"
+            exit 1
+            ;;
+    esac
+done
+
+if [[ "${ipv4}" == false && "${ipv6}" == false ]]; then
+    errcho "WARN: --ipv4 and --ipv6 options are mutually exclusive and will likely prevent output"
+fi
+
+_txt_recursive "${domain}"