workflows: add ip prefix duplicate check

.github/checks/check-ip-prefix-duplicates.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# Change to the locations directory
+cd locations || exit 1
+
+# Extract IPv4 prefixes, sort them, and check for duplicates
+ipv4_duplicates=$(cat ./*.yml | sed -n 's/^\s*prefix:\s*["\']?([^"\'\s#]+)["\']?/\1/p' | sort | uniq -cd)
+
+# Extract IPv6 prefixes, sort them, and check for duplicates
+ipv6_duplicates=$(cat ./*.yml | sed -n 's/^\s*ipv6_prefix:\s*["\']\?\([0-9a-fA-F:]\+::\/[0-9]\+\)["\']\?.*/\1/p' | sort | uniq -cd)
+
+if [ -n "$ipv4_duplicates" ] || [ -n "$ipv6_duplicates" ]; then
+  if [ -n "$ipv4_duplicates" ]; then
+    echo "Duplicate IPv4 prefixes found:"
+    echo "$ipv4_duplicates"
+  fi
+  if [ -n "$ipv6_duplicates" ]; then
+    echo "Duplicate IPv6 prefixes found:"
+    echo "$ipv6_duplicates"
+  fi
+  exit 1
+else
+  echo "No duplicate prefixes found."
+fi

.github/workflows/check-ip-prefix-duplicates.yml

@@ -0,0 +1,17 @@
+---
+name: Check for duplicate IP prefixes
+
+on: [push, pull_request]  # yamllint disable-line rule:truthy
+
+jobs:
+  ipv6-check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Run IP prefix duplicate check
+        run: |
+          ./.github/checks/check-ip-prefix-duplicates.sh