From 4d7e99461d5e18ae835dfbf8413f050db43933bb Mon Sep 17 00:00:00 2001
From: Will Murphy <william@datatitian.com>
Date: Sat, 21 Sep 2019 15:02:50 -0500
Subject: [PATCH] prototype automatic follow acceptance with signed request

---
 routes/inbox.js | 64 ++++++++++++++++++++++++++++++++++++++++++++++++-
 utils/index.js  | 14 ++++++-----
 2 files changed, 71 insertions(+), 7 deletions(-)

diff --git a/routes/inbox.js b/routes/inbox.js
index b8c8d6c..d7a0d59 100644
--- a/routes/inbox.js
+++ b/routes/inbox.js
@@ -1,10 +1,72 @@
 const express = require('express')
 const router = express.Router()
 const utils = require('../utils')
+const request = require('request-promise-native')
+const httpSignature = require('http-signature')
+const {ObjectId} = require('mongodb')
 
 router.post('/', utils.validators.activity, function (req, res) {
   const db = req.app.get('db');
-  req.body._target = req.user
+  let outgoingResponse
+  req.body._meta = {_target: utils.usernameToIRI(req.user)}
+  // side effects
+  switch(req.body.type) {
+    case 'Accept':
+      // workaround for node-http-signature#87
+      const tempUrl = req.url
+      req.url = req.originalUrl
+      sigHead = httpSignature.parse(req, {clockSkew: 3000})
+      req.url = tempUrl
+      // TODO - real key lookup with remote fetch
+      utils.getOrCreateActor(sigHead.keyId.replace(/.*\//, ''), db)
+      .then(user => {
+        const valid = httpSignature.verifySignature(sigHead, user.publicKey.publicKeyPem)
+        console.log('key validation', valid)
+        return res.status(valid ? 200 : 401).send()
+      })
+      break
+    case 'Follow':
+      req.body._meta._target = req.body.object.id
+      // send acceptance reply
+      Promise.all([
+        utils.getOrCreateActor(req.user, db, true),
+        request({
+          url: utils.actorFromActivity(req.body),
+          headers: {Accept: 'application/activity+json'},
+          json: true,
+        })
+      ])
+        .then(([user, actor]) => {
+          if (!actor || !actor.inbox) {
+            throw new Error('unable to send follow request acceptance: actor inbox not retrievable')
+          }
+          const newID = new ObjectId()
+          const responseOpts = {
+            method: 'POST',
+            url: actor.inbox,
+            headers: {
+              'Content-Type': 'application/activity+json',
+            },
+            httpSignature: {
+              key: user._meta.privateKey,
+              keyId: user.id,
+              headers: ['(request-target)', 'host', 'date'],
+            },
+            json: true,
+            body: utils.toJSONLD({
+              _id: newID,
+              type: 'Accept',
+              id: `https://${req.app.get('domain')}/o/${newID.toHexString()}`,
+              actor: user.id,
+              object: req.body,
+            }),
+          }
+          return request(responseOpts)
+        })
+        .then(result => console.log('success', result))
+        .catch(e => console.log(e))
+      break
+  }
   Promise.all([
     db.collection('objects').insertOne(req.body.object),
     db.collection('streams').insertOne(req.body)
diff --git a/utils/index.js b/utils/index.js
index 3d85cd4..be11f8d 100644
--- a/utils/index.js
+++ b/utils/index.js
@@ -51,8 +51,6 @@ function createLocalActor (name, type) {
         privateKeyEncoding: {
             type: 'pkcs8',
             format: 'pem',
-            cipher: 'aes-256-cbc',
-            passphrase: config.KEYPASS
         }
     }).then(pair => {
         const actorBase = usernameToIRI(name);
@@ -80,13 +78,15 @@ function createLocalActor (name, type) {
     })
 }
 module.exports.createLocalActor = createLocalActor
-
-async function getOrCreateActor(preferredUsername, db) {
+const actorProj = {_id: 0, _meta: 0}
+const metaActorProj = {_id: 0}
+async function getOrCreateActor(preferredUsername, db, includeMeta) {
     const id = usernameToIRI(preferredUsername)
     let user = await db.collection('objects')
     .find({id: id})
     .limit(1)
-    .project({_id: 0, _meta: 0})
+    // strict comparison as we don't want to return private keys on accident
+    .project(includeMeta === true ? metaActorProj : actorProj)
     .next()
     if (user) {
         return user
@@ -95,8 +95,10 @@ async function getOrCreateActor(preferredUsername, db) {
     user = await createLocalActor(preferredUsername, 'Group')
     await db.collection('objects').insertOne(user)
     // only executed on success
-    delete user._meta
     delete user._id
+    if (includeMeta !== true) {
+        delete user._meta
+    }
     return user
 }
 module.exports.getOrCreateActor = getOrCreateActor