diff options
Diffstat (limited to 'packages/backend/src/server/ServerService.ts')
| -rw-r--r-- | packages/backend/src/server/ServerService.ts | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/packages/backend/src/server/ServerService.ts b/packages/backend/src/server/ServerService.ts index 690fdcfe29..9ae8f2efe4 100644 --- a/packages/backend/src/server/ServerService.ts +++ b/packages/backend/src/server/ServerService.ts @@ -105,6 +105,43 @@ export class ServerService implements OnApplicationShutdown { serve: false, }); + // if the requester looks like to be performing an ActivityPub object lookup, reject all external redirects + // + // this will break lookup that involve copying a URL from a third-party server, like trying to lookup http://charlie.example.com/@alice@alice.com + // + // this is not required by standard but protect us from peers that did not validate final URL. + if (this.config.disallowExternalApRedirect) { + const maybeApLookupRegex = /application\/activity\+json|application\/ld\+json.+activitystreams/i; + fastify.addHook('onSend', (request, reply, _, done) => { + const location = reply.getHeader('location'); + if (reply.statusCode < 300 || reply.statusCode >= 400 || typeof location !== 'string') { + done(); + return; + } + + if (!maybeApLookupRegex.test(request.headers.accept ?? '')) { + done(); + return; + } + + const effectiveLocation = process.env.NODE_ENV === 'production' ? location : location.replace(/^http:\/\//, 'https://'); + if (effectiveLocation.startsWith(`https://${this.config.host}/`)) { + done(); + return; + } + + reply.status(406); + reply.removeHeader('location'); + reply.header('content-type', 'text/plain; charset=utf-8'); + reply.header('link', `<${encodeURI(location)}>; rel="canonical"`); + done(null, [ + "Refusing to relay remote ActivityPub object lookup.", + "", + `Please remove 'application/activity+json' and 'application/ld+json' from the Accept header or fetch using the authoritative URL at ${location}.`, + ].join('\n')); + }); + } + fastify.register(this.apiServerService.createServer, { prefix: '/api' }); fastify.register(this.openApiServerService.createServer); fastify.register(this.mastodonApiServerService.createServer, { prefix: '/api' }); |