session-desktop/ts/receiver/groups.ts

import { SignalService } from '../protobuf';

const _ = window.Lodash;

function isGroupBlocked(groupId: string) {
  return (
    window.textsecure.storage.get('blocked-groups', []).indexOf(groupId) >= 0
  );
}

function shouldIgnoreBlockedGroup(group: any, senderPubKey: string) {
  const groupId = group.id;
  const isBlocked = isGroupBlocked(groupId);
  const isLeavingGroup = Boolean(
    group.type === SignalService.GroupContext.Type.QUIT
  );

  const primaryDevicePubKey = window.storage.get('primaryDevicePubKey');
  const isMe =
    senderPubKey === window.textsecure.storage.user.getNumber() ||
    senderPubKey === primaryDevicePubKey;

  return isBlocked && !(isMe && isLeavingGroup);
}

/**
 * Returns true if the message is already completely handled and confirmed
 * and the processing of this message must stop.
 */
export async function preprocessGroupMessage(
  source: string,
  group: any,
  primarySource: string
) {
  const conversationId = group.id;
  const conversation = await window.ConversationController.getOrCreateAndWait(
    conversationId,
    'group'
  );

  if (conversation.isPublic()) {
    // window.console.log('No need to preprocess public group chat messages');
    return;
  }
  const GROUP_TYPES = SignalService.GroupContext.Type;

  if (shouldIgnoreBlockedGroup(group, source)) {
    window.log.warn('Message ignored; destined for blocked group');
    return true;
  }

  // NOTE: we use group admins to tell if this is
  // the creation of the group (initial update)
  const groupAdminsSet =
    conversation.get('groupAdmins') &&
    conversation.get('groupAdmins').length > 0;
  const newGroup = !groupAdminsSet;
  const knownMembers = conversation.get('members');

  if (!newGroup && knownMembers) {
    const fromMember = knownMembers.includes(primarySource);
    // if the group exists and we have its members,
    // we must drop a message from anyone else than the existing members.
    if (!fromMember) {
      window.log.warn(
        `Ignoring group message from non-member: ${primarySource}`
      );
      // returning true drops the message
      return true;
    }
  }
  if (group.type === GROUP_TYPES.REQUEST_INFO && !newGroup) {
    window.libloki.api.debug.logGroupRequestInfo(
      `Received GROUP_TYPES.REQUEST_INFO from source: ${source}, primarySource: ${primarySource}, sending back group info.`
    );
    conversation.sendGroupInfo([source]);
    return true;
  }

  if (group.members && group.type === GROUP_TYPES.UPDATE) {
    if (newGroup) {
      conversation.updateGroupAdmins(group.admins);
    } else {
      // be sure to drop a message from a non admin if it tries to change group members
      // or change the group name
      const fromAdmin = conversation.get('groupAdmins').includes(primarySource);

      if (!fromAdmin) {
        // Make sure the message is not removing members / renaming the group
        const nameChanged = conversation.get('name') !== group.name;

        if (nameChanged) {
          window.log.warn('Non-admin attempts to change the name of the group');
        }

        const membersMissing =
          _.difference(conversation.get('members'), group.members).length > 0;

        if (membersMissing) {
          window.log.warn('Non-admin attempts to remove group members');
        }

        const messageAllowed = !nameChanged && !membersMissing;

        // Returning true drops the message
        if (!messageAllowed) {
          return true;
        }
      }
    }
    // send a session request for all the members we do not have a session with
    window.libloki.api.sendSessionRequestsToMembers(group.members);
  } else if (newGroup) {
    // We have an unknown group, we should request info from the sender
    window.textsecure.messaging.requestGroupInfo(conversationId, [
      primarySource,
    ]);
  }
  return false;
}