nip98: add a dedicated nip98 module, refactor auth98.ts

src/middleware/auth98.ts

@@ -1,50 +1,20 @@
 import { type AppMiddleware } from '@/app.ts';
-import { Conf } from '@/config.ts';
-import { type Event, HTTPException } from '@/deps.ts';
-import { decode64Schema, jsonSchema } from '@/schema.ts';
-import { signedEventSchema } from '@/schemas/nostr.ts';
-import { eventAge, findTag, sha256, Time } from '@/utils.ts';
-
-const decodeEventSchema = decode64Schema.pipe(jsonSchema).pipe(signedEventSchema);
-
-interface Auth98Opts {
-  timeout?: number;
-}
+import { HTTPException } from '@/deps.ts';
+import { parseAuthRequest, type ParseAuthRequestOpts } from '@/utils/nip98.ts';
+import { localRequest } from '@/utils/web.ts';
 
 /**
  * NIP-98 auth.
  * https://github.com/nostr-protocol/nips/blob/master/98.md
  */
-function auth98(opts: Auth98Opts = {}): AppMiddleware {
+function auth98(opts: ParseAuthRequestOpts = {}): AppMiddleware {
   return async (c, next) => {
-    const authHeader = c.req.headers.get('authorization');
-    const base64 = authHeader?.match(/^Nostr (.+)$/)?.[1];
-    const { timeout = Time.minutes(1) } = opts;
-
-    const schema = decodeEventSchema
-      .refine((event) => event.kind === 27235)
-      .refine((event) => eventAge(event) < timeout)
-      .refine((event) => findTag(event.tags, 'method')?.[1] === c.req.method)
-      .refine((event) => {
-        const url = findTag(event.tags, 'u')?.[1];
-        try {
-          return url === Conf.local(c.req.url);
-        } catch (_e) {
-          return false;
-        }
-      })
-      .refine(async (event) => {
-        const body = await c.req.raw.clone().text();
-        if (!body) return true;
-        const hash = findTag(event.tags, 'payload')?.[1];
-        return hash === await sha256(body);
-      });
-
-    const result = await schema.safeParseAsync(base64);
+    const req = localRequest(c);
+    const result = await parseAuthRequest(req, opts);
 
     if (result.success) {
       c.set('pubkey', result.data.pubkey);
-      c.set('proof', result.data as Event<27235>);
+      c.set('proof', result.data);
     }
 
     await next();

src/utils.ts

@@ -67,7 +67,7 @@ async function lookupAccount(value: string): Promise<Event<0> | undefined> {
 
 /** Return the event's age in milliseconds. */
 function eventAge(event: Event): number {
-  return new Date().getTime() - nostrDate(event.created_at).getTime();
+  return Date.now() - nostrDate(event.created_at).getTime();
 }
 
 function findTag(tags: string[][], name: string): string[] | undefined {

src/utils/nip98.ts

@@ -0,0 +1,46 @@
+import { type Event } from '@/deps.ts';
+import { decode64Schema, jsonSchema } from '@/schema.ts';
+import { signedEventSchema } from '@/schemas/nostr.ts';
+import { eventAge, findTag, sha256 } from '@/utils.ts';
+import { Time } from '@/utils/time.ts';
+
+/** Decode a Nostr event from a base64 encoded string. */
+const decode64EventSchema = decode64Schema.pipe(jsonSchema).pipe(signedEventSchema);
+
+interface ParseAuthRequestOpts {
+  /** Max event age (in ms). */
+  maxAge?: number;
+  /** Whether to validate the request body of the request with the payload of the auth event. (default: `true`) */
+  validatePayload?: boolean;
+}
+
+/** Parse the auth event from a Request, returning a zod SafeParse type. */
+function parseAuthRequest(req: Request, opts: ParseAuthRequestOpts = {}) {
+  const { maxAge = Time.minutes(1), validatePayload = true } = opts;
+
+  const header = req.headers.get('authorization');
+  const base64 = header?.match(/^Nostr (.+)$/)?.[1];
+
+  const schema = decode64EventSchema
+    .refine((event): event is Event<27235> => event.kind === 27235, 'Event must be kind 27235')
+    .refine((event) => eventAge(event) < maxAge, 'Event expired')
+    .refine((event) => tagValue(event, 'method') === req.method, 'Event method does not match HTTP request method')
+    .refine((event) => tagValue(event, 'u') === req.url, 'Event URL does not match request URL')
+    .refine(validateBody, 'Event payload does not match request body');
+
+  function validateBody(event: Event<27235>) {
+    if (!validatePayload) return true;
+    return req.clone().text()
+      .then(sha256)
+      .then((hash) => hash === tagValue(event, 'payload'));
+  }
+
+  return schema.safeParseAsync(base64);
+}
+
+/** Get the value for the first matching tag name in the event. */
+function tagValue(event: Event, tagName: string): string | undefined {
+  return findTag(event.tags, tagName)?.[1];
+}
+
+export { parseAuthRequest, type ParseAuthRequestOpts };

src/utils/web.ts

@@ -123,4 +123,20 @@ function activityJson<T, P extends string>(c: Context<any, P>, object: T) {
   return response;
 }
 
-export { activityJson, createAdminEvent, createEvent, paginated, type PaginationParams, paginationSchema, parseBody };
+/** Rewrite the URL of the request object to use the local domain. */
+function localRequest(c: Context): Request {
+  return Object.create(c.req.raw, {
+    url: { value: Conf.local(c.req.url) },
+  });
+}
+
+export {
+  activityJson,
+  createAdminEvent,
+  createEvent,
+  localRequest,
+  paginated,
+  type PaginationParams,
+  paginationSchema,
+  parseBody,
+};