feat(cert-manager): Zusammenführen mit Fullchain und Nur Kette

- Kettenbau mit Aussteller- und Signaturprüfung (checkIssued plus verify), Wurzel nur auf Wunsch
- build-Route für Fullchain und Nur Kette (PEM), eigene JSON-Grenze 512 KiB mit 413 und Code tooLarge
- Reiter Zusammenführen mit Kettenansicht, Hinweis bei fehlendem Zwischenzertifikat

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/api/src/cert-manager/cert-analyze.spec.ts

@@ -43,8 +43,20 @@ describe('analyzeWorkingSet', () => {
     expect(result.ignored).toEqual([{ file: 6, path: 'readme.txt', reason: 'unknown' }]);
   });
 
-  it('Ketten und gesperrte Eintraege sind in diesem Stand leer', () => {
-    expect(result.chains).toEqual([]);
+  it('liefert zwei Ketten: RSA unvollstaendig (Luecke nach der CA), EC vollstaendig mit Wurzel', () => {
+    const certs = result.items.filter((i): i is CertItem => i.kind === 'certificate');
+    expect(result.chains).toHaveLength(2);
+    const byHead = (cn: string) =>
+      result.chains.find((c) => certs.find((x) => x.id === c.headId)?.cn === cn);
+    const rsa = byHead('www.example.test');
+    expect(rsa?.complete).toBe(false);
+    expect(rsa?.gap).toMatchObject({ kind: 'afterCa', missingIssuerCn: 'Tessera Test Root RSA' });
+    const ec = byHead('ec.example.test');
+    expect(ec?.complete).toBe(true);
+    expect(certs.find((x) => x.id === ec?.rootId)?.cn).toBe('Tessera Test Root EC');
+  });
+
+  it('gesperrte Eintraege sind in diesem Stand leer', () => {
     expect(result.locked).toEqual([]);
   });
 

apps/api/src/cert-manager/cert-analyze.ts

@@ -1,3 +1,4 @@
+import { buildChains } from './cert-chain';
 import { detectBlob } from './cert-model';
 import type {
   AnalysisResult,
@@ -11,7 +12,7 @@ import type {
 /**
  * Fassade der Analyse (quick-261009-ikt, D-15): alle hochgeladenen Dateien erkennen,
  * gleiche Teile zusammenfassen und ordnen. Zustandslos; nichts wird gespeichert.
- * Ketten (Task 2), Schluessel/CSR-Zuordnung und gesperrte Container (Task 4) folgen.
+ * Ketten ab Task 2; Schluessel/CSR-Zuordnung und gesperrte Container (Task 4) folgen.
  */
 
 export interface AnalyzeFile {
@@ -71,5 +72,7 @@ export function analyzeWorkingSet(files: AnalyzeFile[], passwords: string[] = []
     locked.push(...result.locked);
   });
 
-  return { items: orderItems([...byId.values()]), chains: [], locked, ignored };
+  const items = orderItems([...byId.values()]);
+  const certs = items.filter((i): i is CertItem => i.kind === 'certificate');
+  return { items, chains: buildChains(certs).chains, locked, ignored };
 }

apps/api/src/cert-manager/cert-chain.spec.ts

@@ -0,0 +1,152 @@
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { describe, expect, it } from 'vitest';
+import { buildChains } from './cert-chain';
+import { detectBlob } from './cert-model';
+import type { CertItem } from './cert-types';
+
+const fx = (name: string) => readFileSync(join(__dirname, '__fixtures__', name));
+
+function load(...names: string[]): CertItem[] {
+  const items: CertItem[] = [];
+  names.forEach((name, file) => {
+    const result = detectBlob(fx(name), { file, path: name, passwords: [] });
+    for (const item of result.items) if (item.kind === 'certificate') items.push(item);
+  });
+  return items;
+}
+
+const cnOf = (certs: CertItem[], id: string) => certs.find((c) => c.id === id)?.cn;
+const pathCns = (certs: CertItem[], path: string[]) => path.map((id) => cnOf(certs, id));
+
+describe('buildChains', () => {
+  it('Server + Zwischenzertifikat ohne Wurzel: unvollstaendig, Luecke nach der CA', () => {
+    const certs = load('rsa-leaf.pem', 'rsa-inter.pem');
+    const { chains } = buildChains(certs);
+    expect(chains).toHaveLength(1);
+    expect(pathCns(certs, chains[0].path)).toEqual(['www.example.test', 'Tessera Test Inter RSA']);
+    expect(chains[0].complete).toBe(false);
+    expect(chains[0].rootId).toBeNull();
+    expect(chains[0].gap).toMatchObject({
+      kind: 'afterCa',
+      missingIssuerCn: 'Tessera Test Root RSA',
+    });
+  });
+
+  it('mit Wurzel: vollstaendig, rootId gesetzt, keine Luecke', () => {
+    const certs = load('rsa-leaf.pem', 'rsa-inter.pem', 'rsa-root.pem');
+    const { chains } = buildChains(certs);
+    expect(chains).toHaveLength(1);
+    expect(chains[0].complete).toBe(true);
+    expect(cnOf(certs, chains[0].rootId as string)).toBe('Tessera Test Root RSA');
+    expect(chains[0].gap).toBeNull();
+    expect(chains[0].path).toHaveLength(3);
+  });
+
+  it('nur das Serverzertifikat: Luecke nach dem Server mit Adresse des Ausstellers', () => {
+    const certs = load('rsa-leaf.pem');
+    const { chains } = buildChains(certs);
+    expect(chains[0].gap).toMatchObject({
+      kind: 'afterLeaf',
+      missingIssuerCn: 'Tessera Test Inter RSA',
+      aiaUrls: ['http://pki.example.test/rsa-inter.cer'],
+    });
+  });
+
+  it('gleichnamige CA mit anderem Schluessel (Attrappe) wird nie genommen', () => {
+    const certs = load(
+      'rsa-leaf-noaki.pem',
+      'rsa-inter-decoy.pem',
+      'rsa-inter.pem',
+      'rsa-root.pem',
+    );
+    const { chains } = buildChains(certs);
+    expect(chains).toHaveLength(1);
+    const names = chains[0].path.map((id) => certs.find((c) => c.id === id));
+    expect(names[1]?.sources[0].path).toBe('rsa-inter.pem');
+    expect(chains[0].complete).toBe(true);
+  });
+
+  it('nur die Attrappe vorhanden: die Signaturpruefung lehnt sie ab, Luecke nach dem Server', () => {
+    const certs = load('rsa-leaf-noaki.pem', 'rsa-inter-decoy.pem', 'rsa-root.pem');
+    const { chains } = buildChains(certs);
+    expect(chains).toHaveLength(1);
+    expect(chains[0].path).toHaveLength(1);
+    expect(chains[0].gap?.kind).toBe('afterLeaf');
+  });
+
+  it('kreuzsigniertes Zwischenzertifikat fuehrt zur zweiten Wurzel', () => {
+    const certs = load('rsa-leaf.pem', 'rsa-inter-cross.pem', 'rsa-root2.pem');
+    const { chains } = buildChains(certs);
+    expect(chains[0].complete).toBe(true);
+    expect(cnOf(certs, chains[0].rootId as string)).toBe('Tessera Test Root RSA 2');
+  });
+
+  it('beide Varianten vorhanden: Hauptkette ueber rsa-inter und rsa-root, mindestens eine Alternative', () => {
+    const certs = load('rsa-leaf.pem', 'rsa-inter.pem', 'rsa-inter-cross.pem', 'rsa-root.pem');
+    const { chains } = buildChains(certs);
+    expect(chains).toHaveLength(1);
+    expect(chains[0].complete).toBe(true);
+    expect(cnOf(certs, chains[0].rootId as string)).toBe('Tessera Test Root RSA');
+    expect(chains[0].alternatives).toBeGreaterThanOrEqual(1);
+  });
+
+  it('abgelaufenes Zwischenzertifikat wird nicht als Hauptkette genommen', () => {
+    const certs = load('rsa-leaf.pem', 'rsa-inter-expired.pem', 'rsa-inter.pem', 'rsa-root.pem');
+    const { chains } = buildChains(certs);
+    const middle = certs.find((c) => c.id === chains[0].path[1]);
+    expect(middle?.isExpired).toBe(false);
+    expect(middle?.sources[0].path).toBe('rsa-inter.pem');
+    expect(chains[0].alternatives).toBeGreaterThanOrEqual(1);
+  });
+
+  it('die Reihenfolge der Eingabe aendert die Hauptkette nicht', () => {
+    const names = ['rsa-leaf.pem', 'rsa-inter-expired.pem', 'rsa-inter.pem', 'rsa-root.pem'];
+    const forward = load(...names);
+    const reversed = load(...[...names].reverse());
+    const a = buildChains(forward).chains[0];
+    const b = buildChains(reversed).chains[0];
+    expect(a.path).toEqual(b.path);
+    expect(a.alternatives).toBe(b.alternatives);
+  });
+
+  it('Zwischenzertifikat + Wurzel ohne Serverzertifikat: eine Kette mit dem Zwischenzertifikat als Kopf', () => {
+    const certs = load('rsa-inter.pem', 'rsa-root.pem');
+    const { chains } = buildChains(certs);
+    expect(chains).toHaveLength(1);
+    expect(cnOf(certs, chains[0].headId)).toBe('Tessera Test Inter RSA');
+    expect(chains[0].complete).toBe(true);
+  });
+
+  it('selbstsigniertes Serverzertifikat: Kette aus ihm selbst, vollstaendig, ohne Wurzel', () => {
+    const certs = load('selfsigned-leaf.pem');
+    const { chains } = buildChains(certs);
+    expect(chains[0].path).toEqual([certs[0].id]);
+    expect(chains[0].complete).toBe(true);
+    expect(chains[0].rootId).toBeNull();
+    expect(chains[0].gap).toBeNull();
+  });
+
+  it('EC-Kette wird genauso gebaut', () => {
+    const certs = load('ec-leaf.pem', 'ec-inter.pem', 'ec-root.pem');
+    const { chains } = buildChains(certs);
+    expect(pathCns(certs, chains[0].path)).toEqual([
+      'ec.example.test',
+      'Tessera Test Inter EC',
+      'Tessera Test Root EC',
+    ]);
+    expect(chains[0].complete).toBe(true);
+  });
+
+  it('mit vorgegebenem Kopf wird genau diese Kette gebaut', () => {
+    const certs = load('rsa-leaf.pem', 'rsa-inter.pem', 'rsa-root.pem');
+    const inter = certs.find((c) => c.role === 'intermediate') as CertItem;
+    const { chains } = buildChains(certs, [inter.id]);
+    expect(chains).toHaveLength(1);
+    expect(chains[0].headId).toBe(inter.id);
+  });
+
+  it('leere Menge ergibt keine Ketten', () => {
+    expect(buildChains([])).toEqual({ chains: [] });
+  });
+});

apps/api/src/cert-manager/cert-chain.ts

@@ -0,0 +1,148 @@
+import { X509Certificate } from 'node:crypto';
+import type { CertItem, ChainGap, ChainInfo } from './cert-types';
+
+/**
+ * Kettenbau des Zertifikat-Managers (quick-261009-ikt, D-18). Reine Funktionen, kein Netz.
+ *
+ * Aussteller eines Zertifikats C ist jedes andere Zertifikat I der Menge mit
+ * `C.checkIssued(I) && C.verify(I.publicKey)`: checkIssued vergleicht Namen, Schluesselkennungen
+ * und Schluesselverwendung, die echte Signaturpruefung entscheidet. Nur beides zusammen
+ * schuetzt vor einer gleichnamigen CA mit anderem Schluessel. Ein Abgleich nur ueber Namen
+ * waere falsch (kreuzsignierte und neu ausgestellte Zwischenzertifikate tragen denselben Namen).
+ */
+
+const MAX_DEPTH = 10;
+const MAX_PATHS = 200;
+const MAX_ALTERNATIVES = 10;
+
+interface Node {
+  item: CertItem;
+  x: X509Certificate;
+  /** Menge der Aussteller, die beide Pruefungen bestehen (Indizes in `nodes`) */
+  issuers: number[];
+}
+
+function toNodes(certs: CertItem[]): Node[] {
+  const nodes: Node[] = [];
+  const seen = new Set<string>();
+  for (const item of certs) {
+    if (seen.has(item.id)) continue;
+    seen.add(item.id);
+    try {
+      nodes.push({ item, x: new X509Certificate(item.pem), issuers: [] });
+    } catch {
+      // kein lesbares Zertifikat: gehoert nicht in eine Kette
+    }
+  }
+  nodes.forEach((child, ci) => {
+    nodes.forEach((candidate, ii) => {
+      if (ci === ii) return;
+      try {
+        if (child.x.checkIssued(candidate.x) && child.x.verify(candidate.x.publicKey)) {
+          child.issuers.push(ii);
+        }
+      } catch {
+        // nicht pruefbar (z. B. unbekannter Schluesseltyp): kein Aussteller
+      }
+    });
+  });
+  return nodes;
+}
+
+interface FoundPath {
+  indices: number[];
+  /** endet an einem selbstsignierten Zertifikat */
+  complete: boolean;
+}
+
+function findPaths(nodes: Node[], start: number): FoundPath[] {
+  const found: FoundPath[] = [];
+  const walk = (indices: number[]) => {
+    if (found.length >= MAX_PATHS) return;
+    const last = nodes[indices[indices.length - 1]];
+    if (last.item.selfSigned) {
+      found.push({ indices: [...indices], complete: true });
+      return;
+    }
+    const next = last.issuers.filter((i) => !indices.includes(i));
+    if (next.length === 0 || indices.length >= MAX_DEPTH) {
+      found.push({ indices: [...indices], complete: false });
+      return;
+    }
+    for (const i of next) walk([...indices, i]);
+  };
+  walk([start]);
+  return found;
+}
+
+function notCurrentlyValid(item: CertItem, now: number): boolean {
+  return Date.parse(item.notBefore) > now || Date.parse(item.notAfter) < now;
+}
+
+function rank(nodes: Node[], paths: FoundPath[], now: number): FoundPath[] {
+  const score = (p: FoundPath) => ({
+    complete: p.complete ? 0 : 1,
+    invalid: p.indices.filter((i) => notCurrentlyValid(nodes[i].item, now)).length,
+    length: p.indices.length,
+    firstIssuerEnd: p.indices.length > 1 ? Date.parse(nodes[p.indices[1]].item.notAfter) : 0,
+    key: p.indices.map((i) => nodes[i].item.sha256).join('|'),
+  });
+  const scored = paths.map((p) => ({ p, s: score(p) }));
+  scored.sort(
+    (a, b) =>
+      a.s.complete - b.s.complete ||
+      a.s.invalid - b.s.invalid ||
+      a.s.length - b.s.length ||
+      b.s.firstIssuerEnd - a.s.firstIssuerEnd ||
+      (a.s.key < b.s.key ? -1 : a.s.key > b.s.key ? 1 : 0),
+  );
+  return scored.map((e) => e.p);
+}
+
+function defaultHeads(nodes: Node[]): number[] {
+  const endEntities = nodes.flatMap((n, i) => (n.item.role === 'end-entity' ? [i] : []));
+  if (endEntities.length > 0) return endEntities;
+  const issuing = new Set<number>();
+  for (const n of nodes) for (const i of n.issuers) issuing.add(i);
+  return nodes.flatMap((_, i) => (issuing.has(i) ? [] : [i]));
+}
+
+function chainOf(nodes: Node[], head: number, now: number): ChainInfo {
+  const ranked = rank(nodes, findPaths(nodes, head), now);
+  const primary = ranked[0];
+  const last = nodes[primary.indices[primary.indices.length - 1]].item;
+  let gap: ChainGap | null = null;
+  if (!primary.complete) {
+    gap = {
+      certId: last.id,
+      kind: primary.indices.length === 1 && last.role === 'end-entity' ? 'afterLeaf' : 'afterCa',
+      missingIssuerCn: last.issuerCn,
+      aiaUrls: [...last.aiaIssuerUrls],
+    };
+  }
+  return {
+    headId: nodes[head].item.id,
+    path: primary.indices.map((i) => nodes[i].item.id),
+    rootId: primary.complete && last.role === 'root' ? last.id : null,
+    complete: primary.complete,
+    gap,
+    alternatives: Math.min(ranked.length - 1, MAX_ALTERNATIVES),
+  };
+}
+
+/**
+ * Baut je Kopf eine Kette (Kopf zuerst, dann jeder Aussteller). Standardkoepfe: jedes Serverzertifikat,
+ * sonst jedes Zertifikat, das kein anderes ausgestellt hat. `headIds` waehlt eigene Koepfe.
+ * Das Ergebnis haengt nicht von der Reihenfolge der Eingabe ab.
+ */
+export function buildChains(certs: CertItem[], headIds?: string[]): { chains: ChainInfo[] } {
+  const nodes = toNodes(certs);
+  const heads = headIds
+    ? headIds.flatMap((id) => {
+        const index = nodes.findIndex((n) => n.item.id === id);
+        return index < 0 ? [] : [index];
+      })
+    : defaultHeads(nodes);
+  const now = Date.now();
+  return { chains: heads.map((h) => chainOf(nodes, h, now)) };
+}

apps/api/src/cert-manager/cert-json-body.spec.ts

@@ -0,0 +1,116 @@
+import { PassThrough } from 'node:stream';
+import { describe, expect, it, vi } from 'vitest';
+import {
+  CERT_BUILD_JSON_LIMIT,
+  CERT_BUILD_ROUTE,
+  certBuildBodyErrors,
+  certBuildJsonBody,
+} from './cert-json-body';
+import {
+  CERT_BASENAME_MAX,
+  CERT_PASSWORD_MAX,
+  CERT_PEM_MAX,
+  CERT_POOL_MAX,
+} from './dto/cert-build.dto';
+
+/** PEM-aehnlicher Text: eine Zeile je 64 Zeichen, genau `chars` Zeichen lang. */
+function pemLike(chars: number): string {
+  let out = '';
+  while (out.length < chars) out += `${'A'.repeat(64)}\n`;
+  return out.slice(0, chars);
+}
+
+interface FakeReq extends PassThrough {
+  headers: Record<string, string>;
+  method: string;
+  body?: unknown;
+}
+
+function fakeRequest(raw: string): FakeReq {
+  const req = new PassThrough() as FakeReq;
+  req.headers = {
+    'content-type': 'application/json',
+    'content-length': String(Buffer.byteLength(raw)),
+  };
+  req.method = 'POST';
+  req.end(raw);
+  return req;
+}
+
+function runParser(raw: string): Promise<{ req: FakeReq; error: unknown }> {
+  const req = fakeRequest(raw);
+  return new Promise((resolve) => {
+    certBuildJsonBody(req as never, {} as never, (error?: unknown) => resolve({ req, error }));
+  });
+}
+
+function fakeResponse() {
+  const res = {
+    statusCode: 0,
+    payload: undefined as unknown,
+    status(code: number) {
+      res.statusCode = code;
+      return res;
+    },
+    json(body: unknown) {
+      res.payload = body;
+      return res;
+    },
+  };
+  return res;
+}
+
+describe('cert-json-body (D-26)', () => {
+  it('traegt den Namen certBuildJsonBody, nie jsonParser oder urlencodedParser', () => {
+    expect(certBuildJsonBody.name).toBe('certBuildJsonBody');
+    expect(CERT_BUILD_ROUTE).toBe('/modules/cert-manager/build');
+    expect(CERT_BUILD_JSON_LIMIT).toBe(512 * 1024);
+  });
+
+  it('die groesste Anfrage innerhalb der DTO-Grenzen bleibt unter dem Grenzwert und wird gelesen', async () => {
+    const body = {
+      content: 'fullchain',
+      certPem: pemLike(CERT_PEM_MAX),
+      poolPems: Array.from({ length: CERT_POOL_MAX }, () => pemLike(CERT_PEM_MAX)),
+      keyPem: pemLike(CERT_PEM_MAX),
+      csrPem: pemLike(CERT_PEM_MAX),
+      password: 'p'.repeat(CERT_PASSWORD_MAX),
+      baseName: 'b'.repeat(CERT_BASENAME_MAX),
+    };
+    const raw = JSON.stringify(body);
+    expect(Buffer.byteLength(raw)).toBeLessThan(CERT_BUILD_JSON_LIMIT);
+    const { req, error } = await runParser(raw);
+    expect(error).toBeUndefined();
+    expect((req.body as typeof body).poolPems).toHaveLength(CERT_POOL_MAX);
+  });
+
+  it('eine Anfrage ueber 512 KiB wird mit 413 und Code tooLarge beantwortet', async () => {
+    const { error } = await runParser(JSON.stringify({ content: 'x'.repeat(600 * 1024) }));
+    const res = fakeResponse();
+    const next = vi.fn();
+    certBuildBodyErrors(error, {} as never, res as never, next);
+    expect(res.statusCode).toBe(413);
+    expect(res.payload).toMatchObject({ code: 'tooLarge' });
+    expect(typeof (res.payload as { message: string }).message).toBe('string');
+    expect(next).not.toHaveBeenCalled();
+  });
+
+  it('fehlerhaftes JSON ergibt 400 mit Code invalidInput', async () => {
+    const { error } = await runParser('{"content": ');
+    const res = fakeResponse();
+    const next = vi.fn();
+    certBuildBodyErrors(error, {} as never, res as never, next);
+    expect(res.statusCode).toBe(400);
+    expect(res.payload).toMatchObject({ code: 'invalidInput' });
+    expect(next).not.toHaveBeenCalled();
+  });
+
+  it('jeden anderen Fehler reicht die Funktion unveraendert weiter', () => {
+    const other = new Error('boom');
+    const res = fakeResponse();
+    const next = vi.fn();
+    certBuildBodyErrors(other, {} as never, res as never, next);
+    expect(next).toHaveBeenCalledWith(other);
+    expect(res.statusCode).toBe(0);
+  });
+});

apps/api/src/cert-manager/cert-json-body.ts

@@ -0,0 +1,59 @@
+import { createRequire } from 'node:module';
+import type { NextFunction, Request, Response } from 'express';
+
+/**
+ * Eigener JSON-Leser fuer POST build (quick-261009-ikt, D-26).
+ *
+ * Nests Standardgrenze fuer JSON ist 100 kB. Eine Anfrage innerhalb der DTO-Grenzen
+ * (cert-build.dto.ts) kann aber bis etwa 384 kB gross werden: viele Zertifikate im Pool, dazu
+ * Schluessel und Anfrage. Darum bekommt genau diese Route 512 KiB; jede andere Route behaelt
+ * die 100 kB. Eine groessere Anfrage wird mit 413 und dem Code tooLarge beantwortet (statt mit
+ * einer Antwort ohne Code), fehlerhaftes JSON mit 400 und dem Code invalidInput.
+ *
+ * Registriert wird der Leser in main.ts mit app.use(CERT_BUILD_ROUTE, ...) vor app.listen.
+ * Wichtig:
+ * - Die Funktion darf NICHT jsonParser heissen. Nests Express-Adapter ueberspringt seinen
+ *   globalen JSON-Leser fuer ALLE Routen, sobald eine Schicht mit diesem Namen existiert; dann
+ *   wuerde auch die Anmeldung kein JSON mehr lesen. Darum der Name certBuildJsonBody.
+ * - `express` ist vom API-Paket aus nicht direkt aufloesbar. Es wird ueber @nestjs/platform-express
+ *   geladen, also aus derselben Kopie, die Nest selbst benutzt. Ein neues Paket kommt nicht hinzu.
+ * - body-parser lehnt eine Anfrage ab, deren Koerper schon gelesen ist; Nests globaler Leser liest
+ *   den Koerper daher kein zweites Mal.
+ */
+
+export const CERT_BUILD_ROUTE = '/modules/cert-manager/build';
+export const CERT_BUILD_JSON_LIMIT = 512 * 1024;
+
+const expressFromNest = createRequire(
+  createRequire(__filename).resolve('@nestjs/platform-express'),
+)('express') as typeof import('express');
+
+const parseJson = expressFromNest.json({ limit: CERT_BUILD_JSON_LIMIT });
+
+export function certBuildJsonBody(req: Request, res: Response, next: NextFunction): void {
+  parseJson(req, res, next);
+}
+
+interface BodyParserError {
+  type?: string;
+  status?: number;
+}
+
+/** Fehler des Lesers: zu gross -> 413 tooLarge, kein gueltiges JSON -> 400 invalidInput, sonst weiter. */
+export function certBuildBodyErrors(
+  error: unknown,
+  _req: Request,
+  res: Response,
+  next: NextFunction,
+): void {
+  const e = (error ?? {}) as BodyParserError;
+  if (e.type === 'entity.too.large') {
+    res.status(413).json({ code: 'tooLarge', message: 'Request body exceeds 512 KiB' });
+    return;
+  }
+  if (e.type === 'entity.parse.failed') {
+    res.status(400).json({ code: 'invalidInput', message: 'Request body is not valid JSON' });
+    return;
+  }
+  next(error);
+}

apps/api/src/cert-manager/cert-manager.controller.spec.ts

@@ -32,15 +32,32 @@ describe('CertManagerController', () => {
     expect(Reflect.getMetadata(MODULE_SLUG_KEY, CertManagerController)).toBe('cert-manager');
   });
 
-  it('bietet in diesem Stand genau den Handler analyze (POST analyze, Code 200)', () => {
+  it('bietet in diesem Stand genau die Handler analyze und build (POST, Code 200)', () => {
     const handlers = Object.getOwnPropertyNames(CertManagerController.prototype).filter(
       (n) => n !== 'constructor',
     );
-    expect(handlers).toEqual(['analyze']);
-    const handler = CertManagerController.prototype.analyze;
-    expect(Reflect.getMetadata('path', handler)).toBe('analyze');
-    expect(Reflect.getMetadata('method', handler)).toBe(RequestMethod.POST);
-    expect(Reflect.getMetadata('__httpCode__', handler)).toBe(200);
+    expect(handlers).toEqual(['analyze', 'build']);
+    for (const [name, path] of [
+      ['analyze', 'analyze'],
+      ['build', 'build'],
+    ] as const) {
+      const handler = CertManagerController.prototype[name];
+      expect(Reflect.getMetadata('path', handler)).toBe(path);
+      expect(Reflect.getMetadata('method', handler)).toBe(RequestMethod.POST);
+      expect(Reflect.getMetadata('__httpCode__', handler)).toBe(200);
+    }
+  });
+
+  it('build baut die Fullchain aus den gesendeten Zertifikaten', () => {
+    const text = (n: string) => fx(n).toString('utf8');
+    const result = controller.build({
+      content: 'fullchain',
+      format: 'pem',
+      certPem: text('ec-leaf.pem'),
+      poolPems: [text('ec-inter.pem'), text('ec-root.pem')],
+    });
+    expect(result.files[0].filename).toBe('ec.example.test-fullchain.pem');
+    expect(result.chainComplete).toBe(true);
   });
 
   it('ohne Dateien: 400 invalidInput', () => {

apps/api/src/cert-manager/cert-manager.controller.ts

@@ -1,9 +1,11 @@
-import { Controller, HttpCode, Post, UploadedFiles, UseInterceptors } from '@nestjs/common';
+import { Body, Controller, HttpCode, Post, UploadedFiles, UseInterceptors } from '@nestjs/common';
 import { FilesInterceptor } from '@nestjs/platform-express';
 import type { UploadedFileLike } from '../auth/types/auth-user';
 import { UseModule } from '../module-registry/module.guard';
 import { analyzeWorkingSet } from './cert-analyze';
-import { type AnalysisResult, certError } from './cert-types';
+import { buildOutput } from './cert-output';
+import { type AnalysisResult, type BuildResult, certError } from './cert-types';
+import { BuildOutputDto } from './dto/cert-build.dto';
 
 /** Obergrenzen (D-17): je Datei 5 MiB, alle Dateien zusammen 20 MiB, hoechstens 30 Dateien. */
 export const CERT_MAX_FILES = 30;
@@ -28,7 +30,7 @@ export function repairFileName(name: string): string {
  *
  * Routen (alle POST, 200):
  * - analyze       Task 1  mehrere Dateien (multipart) erkennen und zusammenfassen
- * - build         Task 2  Ausgabe bauen (JSON), ab Task 5/6 erweitert
+ * - build         Task 2  Ausgabe bauen (JSON, eigene Grenze 512 KiB, siehe cert-json-body.ts), ab Task 5/6 erweitert
  * - fetch-issuer  Task 7  fehlendes Zwischenzertifikat nur auf Knopfdruck holen
  */
 @Controller('modules/cert-manager')
@@ -51,4 +53,10 @@ export class CertManagerController {
       files.map((f) => ({ originalname: repairFileName(f.originalname), buffer: f.buffer })),
     );
   }
+
+  @Post('build')
+  @HttpCode(200)
+  build(@Body() dto: BuildOutputDto): BuildResult {
+    return buildOutput(dto);
+  }
 }

apps/api/src/cert-manager/cert-model.ts

@@ -1,5 +1,5 @@
 import { createHash, type KeyObject, X509Certificate } from 'node:crypto';
-import { safeBaseName } from './cert-output';
+import { safeBaseName } from './cert-names';
 import type {
   AnyItem,
   CertItem,

apps/api/src/cert-manager/cert-names.ts

@@ -0,0 +1,14 @@
+/**
+ * Dateinamen-Helfer des Zertifikat-Managers. Eigene Datei, damit cert-model.ts und cert-output.ts
+ * einander nicht gegenseitig einbinden muessen.
+ */
+
+/** Dateiname ohne Pfad und ohne gefaehrliche Zeichen, z. B. „*.example.de“ -> „wildcard.example.de“. */
+export function safeBaseName(raw: string, fallback: string): string {
+  const cleaned = raw
+    .replace(/^\*\./, 'wildcard.')
+    .replace(/[^A-Za-z0-9._-]+/g, '_')
+    .replace(/^[._]+/, '')
+    .slice(0, 80);
+  return cleaned || fallback;
+}

apps/api/src/cert-manager/cert-output.spec.ts

@@ -1,5 +1,30 @@
+import { X509Certificate } from 'node:crypto';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
 import { describe, expect, it } from 'vitest';
-import { safeBaseName } from './cert-output';
+import { buildOutput, safeBaseName } from './cert-output';
+
+const fxText = (name: string) => readFileSync(join(__dirname, '__fixtures__', name), 'utf8');
+
+function decode(file: { content: string }): string {
+  return Buffer.from(file.content, 'base64').toString('utf8');
+}
+
+function subjects(pem: string): string[] {
+  return (pem.match(/-----BEGIN CERTIFICATE-----[\s\S]*?-----END CERTIFICATE-----/g) ?? []).map(
+    (block) => String(new X509Certificate(block).toLegacyObject().subject.CN),
+  );
+}
+
+function codeOf(fn: () => unknown): { status: number; code: string } {
+  try {
+    fn();
+  } catch (error) {
+    const e = error as { getStatus(): number; getResponse(): { code: string } };
+    return { status: e.getStatus(), code: e.getResponse().code };
+  }
+  throw new Error('expected a throw');
+}
 
 describe('safeBaseName', () => {
   it('Platzhalter, Leerzeichen und Pfadteile werden entschaerft', () => {
@@ -16,3 +41,102 @@ describe('safeBaseName', () => {
     expect(safeBaseName('...', 'ersatz')).toBe('ersatz');
   });
 });
+
+describe('buildOutput fullchain und chain', () => {
+  const ecLeaf = fxText('ec-leaf.pem');
+  // absichtlich falsche Reihenfolge plus ein fremdes Zwischenzertifikat
+  const pool = [fxText('ec-root.pem'), fxText('ec-inter.pem'), fxText('rsa-inter.pem')];
+
+  it('Fullchain: Server zuerst, dann Zwischenzertifikat, ohne Wurzel und ohne Fremdes', () => {
+    const r = buildOutput({ content: 'fullchain', format: 'pem', certPem: ecLeaf, poolPems: pool });
+    expect(r.files).toHaveLength(1);
+    expect(r.files[0].filename).toBe('ec.example.test-fullchain.pem');
+    expect(r.files[0].mimeType).toBe('application/x-pem-file');
+    expect(subjects(decode(r.files[0]))).toEqual(['ec.example.test', 'Tessera Test Inter EC']);
+    expect(decode(r.files[0]).endsWith('\n')).toBe(true);
+    expect(r.chainComplete).toBe(true);
+    expect(r.missingIssuerCn).toBeNull();
+  });
+
+  it('Fullchain mit Wurzel: drei Bloecke, Wurzel zuletzt', () => {
+    const r = buildOutput({
+      content: 'fullchain',
+      format: 'pem',
+      certPem: ecLeaf,
+      poolPems: pool,
+      includeRoot: true,
+    });
+    expect(subjects(decode(r.files[0]))).toEqual([
+      'ec.example.test',
+      'Tessera Test Inter EC',
+      'Tessera Test Root EC',
+    ]);
+  });
+
+  it('Nur Kette: nur das Zwischenzertifikat, mit Wurzel beide', () => {
+    const only = buildOutput({ content: 'chain', format: 'pem', certPem: ecLeaf, poolPems: pool });
+    expect(only.files[0].filename).toBe('ec.example.test-chain.pem');
+    expect(subjects(decode(only.files[0]))).toEqual(['Tessera Test Inter EC']);
+    const withRoot = buildOutput({
+      content: 'chain',
+      format: 'pem',
+      certPem: ecLeaf,
+      poolPems: pool,
+      includeRoot: true,
+    });
+    expect(subjects(decode(withRoot.files[0]))).toEqual([
+      'Tessera Test Inter EC',
+      'Tessera Test Root EC',
+    ]);
+  });
+
+  it('Nur Kette ohne Zwischenzertifikat: 400 noChain', () => {
+    expect(
+      codeOf(() =>
+        buildOutput({ content: 'chain', format: 'pem', certPem: fxText('rsa-leaf.pem') }),
+      ),
+    ).toEqual({ status: 400, code: 'noChain' });
+  });
+
+  it('kein Zertifikat in certPem oder im Pool: 400 notACertificate', () => {
+    expect(
+      codeOf(() =>
+        buildOutput({ content: 'fullchain', format: 'pem', certPem: 'kein Zertifikat' }),
+      ),
+    ).toEqual({ status: 400, code: 'notACertificate' });
+    expect(
+      codeOf(() =>
+        buildOutput({ content: 'fullchain', format: 'pem', certPem: ecLeaf, poolPems: ['x'] }),
+      ),
+    ).toEqual({ status: 400, code: 'notACertificate' });
+  });
+
+  it('ohne certPem: 400 invalidInput', () => {
+    expect(codeOf(() => buildOutput({ content: 'fullchain', format: 'pem' }))).toEqual({
+      status: 400,
+      code: 'invalidInput',
+    });
+  });
+
+  it('Luecke wird gemeldet: Server + Zwischenzertifikat ohne Wurzel', () => {
+    const r = buildOutput({
+      content: 'fullchain',
+      format: 'pem',
+      certPem: fxText('rsa-leaf.pem'),
+      poolPems: [fxText('rsa-inter.pem')],
+    });
+    expect(r.chainComplete).toBe(false);
+    expect(r.missingIssuerCn).toBe('Tessera Test Root RSA');
+    expect(subjects(decode(r.files[0]))).toEqual(['www.example.test', 'Tessera Test Inter RSA']);
+  });
+
+  it('Dateiname aus baseName, bereinigt', () => {
+    const r = buildOutput({
+      content: 'fullchain',
+      format: 'pem',
+      certPem: ecLeaf,
+      baseName: '../mein Server',
+    });
+    expect(r.files[0].filename).toBe('mein_Server-fullchain.pem');
+  });
+});

apps/api/src/cert-manager/cert-output.ts

@@ -1,14 +1,82 @@
+import { X509Certificate } from 'node:crypto';
+import { buildChains } from './cert-chain';
+import { certItemFromDer } from './cert-model';
+import { safeBaseName } from './cert-names';
+import {
+  type BuildFile,
+  type BuildInput,
+  type BuildResult,
+  type CertItem,
+  certError,
+} from './cert-types';
+
 /**
- * Ausgabe-Bausteine des Zertifikat-Managers (quick-261009-ikt).
- * Task 1: nur der Dateiname-Helfer; die Ausgabeformate (build) kommen in den folgenden Tasks.
+ * Ausgabe-Bausteine des Zertifikat-Managers (quick-261009-ikt, D-19).
+ * Task 2: Fullchain und Nur Kette als PEM. Die weiteren Inhalte und Formate (Task 5) kommen in
+ * dieselbe Funktion. Die Reihenfolge baut die API immer selbst aus den gesendeten Zertifikaten
+ * (buildChains); eine vom Browser mitgeschickte Reihenfolge wird nie uebernommen.
  */
 
-/** Dateiname ohne Pfad und ohne gefaehrliche Zeichen, z. B. „*.example.de“ -> „wildcard.example.de“. */
-export function safeBaseName(raw: string, fallback: string): string {
-  const cleaned = raw
-    .replace(/^\*\./, 'wildcard.')
-    .replace(/[^A-Za-z0-9._-]+/g, '_')
-    .replace(/^[._]+/, '')
-    .slice(0, 80);
-  return cleaned || fallback;
+export { safeBaseName };
+
+const PEM_MIME = 'application/x-pem-file';
+
+function parseCertificate(pem: unknown): CertItem {
+  if (typeof pem !== 'string' || pem.trim() === '') {
+    certError('notACertificate', 400, 'Value is not a certificate');
+  }
+  try {
+    return certItemFromDer(new X509Certificate(pem).raw, { file: 0, path: '' });
+  } catch {
+    return certError('notACertificate', 400, 'Value is not a certificate');
+  }
+}
+
+/** PEM-Bloecke in Kettenreihenfolge, jeder genau einmal mit abschliessendem Zeilenumbruch. */
+function joinPem(certs: CertItem[]): string {
+  return certs.map((c) => `${c.pem.trim()}\n`).join('');
+}
+
+function pemFile(filename: string, certs: CertItem[]): BuildFile {
+  return {
+    filename,
+    content: Buffer.from(joinPem(certs), 'utf8').toString('base64'),
+    mimeType: PEM_MIME,
+  };
+}
+
+/** Baut die gewuenschte Ausgabe. Wirft Nest-Ausnahmen mit Code (D-24); nie mit Passwort oder Schluessel im Text. */
+export function buildOutput(input: BuildInput): BuildResult {
+  if (!input.certPem) certError('invalidInput', 400, 'certPem is required');
+  const head = parseCertificate(input.certPem);
+  const pool = (input.poolPems ?? []).map(parseCertificate);
+
+  const unique = new Map<string, CertItem>();
+  for (const c of [head, ...pool]) if (!unique.has(c.id)) unique.set(c.id, c);
+  const all = [...unique.values()];
+
+  const chain = buildChains(all, [head.id]).chains[0];
+  const byId = new Map(all.map((c) => [c.id, c]));
+  const path = chain.path.map((id) => byId.get(id) as CertItem);
+  const includeRoot = input.includeRoot === true;
+  const withoutRoot = path.filter((c) => !(c.role === 'root' && c.id !== head.id));
+  const base = safeBaseName(input.baseName ?? '', head.baseName);
+
+  let files: BuildFile[];
+  if (input.content === 'fullchain') {
+    files = [pemFile(`${base}-fullchain.pem`, includeRoot ? path : withoutRoot)];
+  } else if (input.content === 'chain') {
+    const issuers = (includeRoot ? path : withoutRoot).filter((c) => c.id !== head.id);
+    if (issuers.length === 0)
+      certError('noChain', 400, 'No intermediate or root certificate available');
+    files = [pemFile(`${base}-chain.pem`, issuers)];
+  } else {
+    return certError('formatNotPossible', 400, 'Output not available');
+  }
+
+  return {
+    files,
+    chainComplete: chain.complete,
+    missingIssuerCn: chain.gap?.missingIssuerCn ?? null,
+  };
 }

apps/api/src/cert-manager/dto/cert-build.dto.ts

@@ -0,0 +1,58 @@
+import {
+  ArrayMaxSize,
+  IsArray,
+  IsBoolean,
+  IsIn,
+  IsOptional,
+  IsString,
+  MaxLength,
+} from 'class-validator';
+
+/**
+ * Anfrage fuer POST build (quick-261009-ikt, D-19). Die Obergrenzen stehen hier als Konstanten,
+ * weil cert-json-body.ts daraus die groesste gueltige Anfrage berechnet (D-26):
+ *
+ *   certPem 16 384 + 20 x poolPems 16 384 + keyPem 16 384 + csrPem 16 384 Zeichen
+ *   + password 256 + baseName 120 + JSON-Maskierung der Zeilenumbrueche (etwa +1,6 %)
+ *   = rund 384 kB, also deutlich unter dem Grenzwert von 512 KiB.
+ *
+ * Task 2 kennt nur Fullchain und Nur Kette als PEM; weitere Inhalte, Formate und Felder
+ * (Schluessel, Passwort, Vorlage) folgen in Task 5 und 6.
+ */
+export const CERT_PEM_MAX = 16_384;
+export const CERT_POOL_MAX = 20;
+export const CERT_PASSWORD_MAX = 256;
+export const CERT_BASENAME_MAX = 120;
+
+export const BUILD_CONTENTS = ['fullchain', 'chain'] as const;
+export const BUILD_FORMATS = ['pem'] as const;
+
+export class BuildOutputDto {
+  @IsIn(BUILD_CONTENTS)
+  content!: (typeof BUILD_CONTENTS)[number];
+
+  @IsOptional()
+  @IsIn(BUILD_FORMATS)
+  format?: (typeof BUILD_FORMATS)[number];
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(CERT_PEM_MAX)
+  certPem?: string;
+
+  @IsOptional()
+  @IsArray()
+  @ArrayMaxSize(CERT_POOL_MAX)
+  @IsString({ each: true })
+  @MaxLength(CERT_PEM_MAX, { each: true })
+  poolPems?: string[];
+
+  @IsOptional()
+  @IsBoolean()
+  includeRoot?: boolean;
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(CERT_BASENAME_MAX)
+  baseName?: string;
+}