feat(kibana-security-health-check): collect response headers and reso…

…urces information

kibana-security-health-check/src/index.ts

@@ -1,3 +1,69 @@
-export function run() {
-  return 'Hello, world!';
+interface State {
+  headers: Record<string, string>;
+  resources: {
+    external: WebPageResource[];
+    internalCount: number;
+    internalTotalSize: string;
+  };
+}
+
+interface WebPageResource {
+  url: string;
+  data: string;
+  type: 'script' | 'stylesheet';
+}
+
+const TRACKED_RESPONSE_HEADERS = [
+  'content-security-policy',
+  'cross-origin-opener-policy',
+  'permissions-policy',
+  'referrer-policy',
+  'strict-transport-security',
+  'x-content-type-options',
+  'x-found-handling-cluster',
+  'x-frame-options',
+];
+
+export function run(
+  previousContent: State | undefined,
+  remoteResources: WebPageResource[],
+  responseHeaders: Record<string, string>,
+): State {
+  const { externalResources, internalResources } = remoteResources.reduce(
+    (acc, resource) => {
+      if (resource.url.startsWith(location.origin)) {
+        acc.internalResources.push(resource);
+      } else {
+        acc.externalResources.push(resource);
+      }
+      return acc;
+    },
+    { externalResources: [] as WebPageResource[], internalResources: [] as WebPageResource[] },
+  );
+
+  return {
+    headers: Object.fromEntries(
+      Object.entries(responseHeaders).filter(([key]) => TRACKED_RESPONSE_HEADERS.includes(key.toLowerCase())),
+    ),
+    resources: {
+      external: externalResources,
+      internalCount: internalResources.length,
+      internalTotalSize: formatBytes(
+        internalResources.reduce((sum, res) => sum + res.data.length, 0),
+        3,
+      ),
+    },
+  };
+}
+
+function formatBytes(bytes: number, decimals: number) {
+  if (bytes == 0) {
+    return '0 Bytes';
+  }
+
+  const k = 1024,
+    dm = decimals || 2,
+    sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
+    i = Math.floor(Math.log(bytes) / Math.log(k));
+  return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
 }