seth.computer
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Security hardening: CSRF protection, input validation, secure file permissions
Security fixes based on adversarial audit:
1. CSRF Protection (CRITICAL)
- Added CSRF middleware with double-submit cookie pattern
- All POST forms now include hidden _csrf field
- Tokens validated on all state-changing requests
2. Private Key Permissions (HIGH)
- Private key now written with mode 0600 (owner read/write only)
- Prevents other system users from reading the key
3. Input Validation (MEDIUM)
- Added TID format validation for rkey parameters
- Prevents potential path traversal or injection via malformed IDs
4. Added validation library for future use
- TID validation
- HTTPS URL validation
- String sanitization helper
Co-authored-by: Shelley <shelley@exe.dev>
+172
-3
+81
src/lib/csrf.ts
+81
src/lib/csrf.ts
···
1
+
import type { Context, Next } from 'hono';
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import { getCookie, setCookie } from 'hono/cookie';
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const CSRF_COOKIE_NAME = 'csrf_token';
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const CSRF_HEADER_NAME = 'x-csrf-token';
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const CSRF_FORM_FIELD = '_csrf';
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/**
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* Generate a cryptographically secure random token
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*/
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function generateToken(): string {
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const buffer = new Uint8Array(32);
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crypto.getRandomValues(buffer);
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return Array.from(buffer, b => b.toString(16).padStart(2, '0')).join('');
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}
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/**
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* Get or create a CSRF token for the current session
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*/
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export function getCSRFToken(c: Context): string {
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let token = getCookie(c, CSRF_COOKIE_NAME);
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if (!token) {
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token = generateToken();
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setCookie(c, CSRF_COOKIE_NAME, token, {
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httpOnly: true,
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secure: process.env.PUBLIC_URL?.startsWith('https') || false,
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sameSite: 'Strict',
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path: '/',
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maxAge: 60 * 60 * 24, // 24 hours
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});
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}
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return token;
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}
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/**
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* Middleware to validate CSRF token on POST/PUT/DELETE requests
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*/
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export async function csrfProtection(c: Context, next: Next) {
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const method = c.req.method.toUpperCase();
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// Only check CSRF for state-changing methods
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if (['POST', 'PUT', 'DELETE', 'PATCH'].includes(method)) {
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const cookieToken = getCookie(c, CSRF_COOKIE_NAME);
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if (!cookieToken) {
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return c.text('CSRF token missing', 403);
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}
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// Check header first (for AJAX requests)
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let requestToken = c.req.header(CSRF_HEADER_NAME);
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// Fall back to form field
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if (!requestToken) {
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const contentType = c.req.header('content-type') || '';
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if (contentType.includes('application/x-www-form-urlencoded') ||
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contentType.includes('multipart/form-data')) {
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try {
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const body = await c.req.parseBody();
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requestToken = body[CSRF_FORM_FIELD] as string;
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} catch {
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// Body might have already been parsed
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}
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}
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}
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if (!requestToken || requestToken !== cookieToken) {
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return c.text('CSRF token invalid', 403);
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}
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}
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await next();
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}
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/**
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* HTML helper to generate a hidden CSRF input field
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*/
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export function csrfField(token: string): string {
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return `<input type="hidden" name="${CSRF_FORM_FIELD}" value="${token}" />`;
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}
+2
-2
src/lib/oauth.ts
+2
-2
src/lib/oauth.ts
···
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const key = await JoseKey.generate(['ES256'], crypto.randomUUID());
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const jwk = key.privateJwk;
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// Save to disk
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fs.writeFileSync(KEYS_PATH, JSON.stringify(jwk, null, 2));
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// Save to disk with restrictive permissions (owner read/write only)
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fs.writeFileSync(KEYS_PATH, JSON.stringify(jwk, null, 2), { mode: 0o600 });
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return key;
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}
+30
src/lib/validation.ts
+30
src/lib/validation.ts
···
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/**
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* Validate that a string is a valid TID (Timestamp ID)
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* TIDs are base36 encoded and should be 13 characters
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*/
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export function isValidTID(tid: string): boolean {
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if (!tid || typeof tid !== 'string') return false;
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// TID should be 13 characters of base36 (0-9, a-z)
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return /^[0-9a-z]{13}$/.test(tid);
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}
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/**
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* Validate that a URL is a valid HTTPS URL
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*/
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export function isValidHttpsUrl(url: string): boolean {
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try {
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const parsed = new URL(url);
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return parsed.protocol === 'https:';
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} catch {
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return false;
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}
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}
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/**
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* Sanitize a string for safe display (basic XSS prevention)
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* Note: Hono's html template already escapes, but this is defense in depth
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*/
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export function sanitizeString(str: string, maxLength: number = 1000): string {
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if (!str || typeof str !== 'string') return '';
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return str.slice(0, maxLength);
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}
+3
src/routes/auth.ts
+3
src/routes/auth.ts
···
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import { html } from 'hono/html';
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import { getOAuthClient, getClientMetadata, getJwks, deleteSession } from '../lib/oauth';
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import { layout } from '../views/layouts/main';
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import { csrfField } from '../lib/csrf';
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export const authRoutes = new Hono();
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···
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// Login page
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authRoutes.get('/login', async (c) => {
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const error = c.req.query('error');
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const csrfToken = c.get('csrfToken') as string;
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const content = html`
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<div class="auth-form">
···
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` : ''}
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<form action="/auth/login" method="POST">
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${csrfField(csrfToken)}
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<div class="form-group">
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<label for="handle">Handle or DID</label>
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<input
+37
src/routes/documents.ts
+37
src/routes/documents.ts
···
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import { html, raw } from 'hono/html';
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import { layout } from '../views/layouts/main';
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import { requireAuth, type Session } from '../lib/session';
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import { csrfField } from '../lib/csrf';
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import { isValidTID } from '../lib/validation';
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export const documentRoutes = new Hono();
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···
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// No publication yet, will need URL
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}
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const csrfToken = c.get('csrfToken') as string;
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const content = html`
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<div class="form-page">
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<h1>New Document</h1>
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<form action="/documents/new" method="POST" class="document-form">
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${csrfField(csrfToken)}
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<input type="hidden" name="publicationUri" value="${publicationUri}" />
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<div class="form-group">
···
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}
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const rkey = c.req.param('rkey');
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// Validate rkey format
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if (!isValidTID(rkey)) {
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return c.redirect('/documents');
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}
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try {
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const response = await session.agent!.com.atproto.repo.getRecord({
···
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const doc = response.data.value as any;
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const isDraft = (doc.tags || []).includes('draft');
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const csrfToken = c.get('csrfToken') as string;
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const content = html`
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<div class="document-view">
···
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<a href="/documents/${rkey}/edit" class="btn btn-primary">Edit</a>
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${isDraft ? html`
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<form action="/documents/${rkey}/publish" method="POST" style="display:inline">
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${csrfField(csrfToken)}
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<button type="submit" class="btn btn-success">Publish</button>
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</form>
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` : html`
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<form action="/documents/${rkey}/unpublish" method="POST" style="display:inline">
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${csrfField(csrfToken)}
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<button type="submit" class="btn btn-secondary">Unpublish</button>
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</form>
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`}
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<form action="/documents/${rkey}/delete" method="POST" style="display:inline" onsubmit="return confirm('Are you sure you want to delete this document?')">
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${csrfField(csrfToken)}
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<button type="submit" class="btn btn-danger">Delete</button>
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</form>
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<a href="/documents" class="btn btn-secondary">Back to List</a>
···
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}
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const rkey = c.req.param('rkey');
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if (!isValidTID(rkey)) {
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return c.redirect('/documents');
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}
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try {
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const response = await session.agent!.com.atproto.repo.getRecord({
···
329
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});
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const doc = response.data.value as any;
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const csrfToken = c.get('csrfToken') as string;
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const content = html`
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<div class="form-page">
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<h1>Edit Document</h1>
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<form action="/documents/${rkey}/edit" method="POST" class="document-form">
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${csrfField(csrfToken)}
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<div class="form-group">
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<label for="title">Title *</label>
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<input type="text" id="title" name="title" value="${doc.title}" required maxlength="128" />
···
385
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}
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const rkey = c.req.param('rkey');
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if (!isValidTID(rkey)) {
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return c.redirect('/documents');
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}
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const body = await c.req.parseBody();
389
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try {
···
441
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}
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const rkey = c.req.param('rkey');
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if (!isValidTID(rkey)) {
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return c.redirect('/documents');
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}
444
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try {
446
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const existing = await session.agent!.com.atproto.repo.getRecord({
···
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}
484
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const rkey = c.req.param('rkey');
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516
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if (!isValidTID(rkey)) {
517
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return c.redirect('/documents');
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}
486
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487
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try {
488
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const existing = await session.agent!.com.atproto.repo.getRecord({
···
524
557
}
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const rkey = c.req.param('rkey');
560
+
561
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if (!isValidTID(rkey)) {
562
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return c.redirect('/documents');
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+
}
527
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528
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try {
529
566
await session.agent!.com.atproto.repo.deleteRecord({
+7
src/routes/publication.ts
+7
src/routes/publication.ts
···
2
2
import { html } from 'hono/html';
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import { layout } from '../views/layouts/main';
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import { requireAuth, type Session } from '../lib/session';
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+
import { csrfField } from '../lib/csrf';
5
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6
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export const publicationRoutes = new Hono();
7
8
···
63
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return c.redirect('/auth/login');
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}
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const csrfToken = c.get('csrfToken') as string;
68
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const content = html`
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<div class="form-page">
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<h1>Create Publication</h1>
69
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<form action="/publication/new" method="POST">
74
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${csrfField(csrfToken)}
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<div class="form-group">
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<label for="name">Name *</label>
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<input type="text" id="name" name="name" required maxlength="128" />
···
153
157
const pub = publication.value as any;
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const rkey = publication.uri.split('/').pop();
155
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+
const csrfToken = c.get('csrfToken') as string;
161
+
156
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const content = html`
157
163
<div class="form-page">
158
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<h1>Edit Publication</h1>
159
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160
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<form action="/publication/edit" method="POST">
167
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${csrfField(csrfToken)}
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<input type="hidden" name="rkey" value="${rkey}" />
162
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163
170
<div class="form-group">
+11
-1
src/server.ts
+11
-1
src/server.ts
···
8
8
import { homePage } from './views/home';
9
9
import { getSession } from './lib/session';
10
10
import { getClientMetadata, getJwks } from './lib/oauth';
11
+
import { csrfProtection, getCSRFToken } from './lib/csrf';
11
12
12
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export const app = new Hono();
13
14
···
42
43
}
43
44
});
44
45
45
-
// Session middleware - adds session to context
46
+
// Session middleware - adds session and CSRF token to context
46
47
app.use('*', async (c, next) => {
47
48
const session = await getSession(c);
48
49
c.set('session', session);
50
+
// Generate CSRF token for all requests (sets cookie if not present)
51
+
const csrfToken = getCSRFToken(c);
52
+
c.set('csrfToken', csrfToken);
49
53
await next();
50
54
});
55
+
56
+
// CSRF protection for state-changing requests
57
+
// Applied after session middleware but before routes
58
+
app.use('/auth/*', csrfProtection);
59
+
app.use('/publication/*', csrfProtection);
60
+
app.use('/documents/*', csrfProtection);
51
61
52
62
// Home page
53
63
app.get('/', async (c) => {