PeerTube/server/core/lib/activitypub/process/process-follow.ts

import { Transaction } from 'sequelize'
import { ActivityFollow } from '@peertube/peertube-models'
import { isBlockedByServerOrAccount } from '@server/lib/blocklist.js'
import { AccountModel } from '@server/models/account/account.js'
import { getServerActor } from '@server/models/application/application.js'
import { retryTransactionWrapper } from '../../../helpers/database-utils.js'
import { logger } from '../../../helpers/logger.js'
import { CONFIG } from '../../../initializers/config.js'
import { sequelizeTypescript } from '../../../initializers/database.js'
import { getAPId } from '../../../lib/activitypub/activity.js'
import { ActorFollowModel } from '../../../models/actor/actor-follow.js'
import { ActorModel } from '../../../models/actor/actor.js'
import { APProcessorOptions } from '../../../types/activitypub-processor.model.js'
import { MActorFollow, MActorFull, MActorId, MActorSignature } from '../../../types/models/index.js'
import { Notifier } from '../../notifier/index.js'
import { autoFollowBackIfNeeded } from '../follow.js'
import { sendAccept, sendReject } from '../send/index.js'

async function processFollowActivity (options: APProcessorOptions<ActivityFollow>) {
  const { activity, byActor } = options

  const activityId = activity.id
  const objectId = getAPId(activity.object)

  return retryTransactionWrapper(processFollow, byActor, activityId, objectId)
}

// ---------------------------------------------------------------------------

export {
  processFollowActivity
}

// ---------------------------------------------------------------------------

async function processFollow (byActor: MActorSignature, activityId: string, targetActorURL: string) {
  const { actorFollow, created, targetActor } = await sequelizeTypescript.transaction(async t => {
    const targetActor = await ActorModel.loadByUrlAndPopulateAccountAndChannel(targetActorURL, t)

    if (!targetActor) throw new Error('Unknown actor')
    if (targetActor.isOwned() === false) throw new Error('This is not a local actor.')

    if (await rejectIfInstanceFollowDisabled(byActor, activityId, targetActor)) return { actorFollow: undefined }
    if (await rejectIfMuted(byActor, activityId, targetActor)) return { actorFollow: undefined }

    const [ actorFollow, created ] = await ActorFollowModel.findOrCreateCustom({
      byActor,
      targetActor,
      activityId,
      state: await isFollowingInstance(targetActor) && CONFIG.FOLLOWERS.INSTANCE.MANUAL_APPROVAL
        ? 'pending'
        : 'accepted',
      transaction: t
    })

    if (rejectIfAlreadyRejected(actorFollow, byActor, activityId, targetActor)) return { actorFollow: undefined }

    await acceptIfNeeded(actorFollow, targetActor, t)

    await fixFollowURLIfNeeded(actorFollow, activityId, t)

    actorFollow.ActorFollower = byActor
    actorFollow.ActorFollowing = targetActor

    // Target sends to actor he accepted the follow request
    if (actorFollow.state === 'accepted') {
      sendAccept(actorFollow)

      await autoFollowBackIfNeeded(actorFollow, t)
    }

    return { actorFollow, created, targetActor }
  })

  // Rejected
  if (!actorFollow) return

  if (created) {
    const follower = await ActorModel.loadFull(byActor.id)
    const actorFollowFull = Object.assign(actorFollow, { ActorFollowing: targetActor, ActorFollower: follower })

    if (await isFollowingInstance(targetActor)) {
      Notifier.Instance.notifyOfNewInstanceFollow(actorFollowFull)
    } else {
      Notifier.Instance.notifyOfNewUserFollow(actorFollowFull)
    }
  }

  logger.info('Actor %s is followed by actor %s.', targetActorURL, byActor.url)
}

async function rejectIfInstanceFollowDisabled (byActor: MActorSignature, activityId: string, targetActor: MActorFull) {
  if (await isFollowingInstance(targetActor) && CONFIG.FOLLOWERS.INSTANCE.ENABLED === false) {
    logger.info('Rejecting %s because instance followers are disabled.', targetActor.url)

    sendReject(activityId, byActor, targetActor)

    return true
  }

  return false
}

async function rejectIfMuted (byActor: MActorSignature, activityId: string, targetActor: MActorFull) {
  const followerAccount = await AccountModel.load(byActor.Account.id)
  const followingAccountId = targetActor.Account

  if (followerAccount && await isBlockedByServerOrAccount(followerAccount, followingAccountId)) {
    logger.info('Rejecting %s because follower is muted.', byActor.url)

    sendReject(activityId, byActor, targetActor)

    return true
  }

  return false
}

function rejectIfAlreadyRejected (actorFollow: MActorFollow, byActor: MActorSignature, activityId: string, targetActor: MActorFull) {
  // Already rejected
  if (actorFollow.state === 'rejected') {
    logger.info('Rejecting %s because follow is already rejected.', byActor.url)

    sendReject(activityId, byActor, targetActor)

    return true
  }

  return false
}

async function acceptIfNeeded (actorFollow: MActorFollow, targetActor: MActorFull, transaction: Transaction) {
  // Set the follow as accepted if the remote actor follows a channel or account
  // Or if the instance automatically accepts followers
  if (actorFollow.state === 'accepted') return
  if (!await isFollowingInstance(targetActor)) return
  if (CONFIG.FOLLOWERS.INSTANCE.MANUAL_APPROVAL === true && await isFollowingInstance(targetActor)) return

  actorFollow.state = 'accepted'

  await actorFollow.save({ transaction })
}

async function fixFollowURLIfNeeded (actorFollow: MActorFollow, activityId: string, transaction: Transaction) {
  // Before PeerTube V3 we did not save the follow ID. Try to fix these old follows
  if (!actorFollow.url) {
    actorFollow.url = activityId
    await actorFollow.save({ transaction })
  }
}

async function isFollowingInstance (targetActor: MActorId) {
  const serverActor = await getServerActor()

  return targetActor.id === serverActor.id
}