forked-synapse/docs/consent_tracking.md

Support in Synapse for tracking agreement to server terms and conditions

Synapse 0.30 introduces support for tracking whether users have agreed to the terms and conditions set by the administrator of a server - and blocking access to the server until they have.

There are several parts to this functionality; each requires some specific configuration in homeserver.yaml to be enabled.

Note that various parts of the configuation and this document refer to the "privacy policy": agreement with a privacy policy is one particular use of this feature, but of course adminstrators can specify other terms and conditions unrelated to "privacy" per se.

Collecting policy agreement from a user

Synapse can be configured to serve the user a simple policy form with an "accept" button. Clicking "Accept" records the user's acceptance in the database and shows a success page.

To enable this, first create templates for the policy and success pages. These should be stored on the local filesystem.

These templates use the Jinja2 templating language, and the privacy_policy_templates subdirectory of this docs directory gives examples of the sort of thing that can be done.

Note that the templates must be stored under a name giving the language of the template - currently this must always be en (for "English"); internationalisation support is intended for the future.

The template for the policy itself should be versioned - for example 1.0.html. The version of the policy which the user has agreed to is stored in the database.

Once the templates are in place, make the following changes to homeserver.yaml:

1. Add a user_consent section, which should look like:

   user_consent:
     template_dir: privacy_policy_templates
     version: 1.0
   

   template_dir points to the directory containing the policy templates. version defines the version of the policy which will be served to the user. In the example above, Synapse will serve privacy_policy_templates/en/1.0.html.

2. Add a form_secret setting at the top level:

   form_secret: "<unique secret>"
   

   This should be set to an arbitrary secret string (try pwgen -y 30 to generate suitable secrets).

   More on what this is used for below.

3. Add consent wherever the client resource is currently enabled in the listeners configuration. For example:

   listeners:
     - port: 8008
       resources:
         - names:
           - client
           - consent
   

Finally, ensure that jinja2 is installed. If you are using a virtualenv, this should be a matter of pip install Jinja2. On debian, try apt-get install python-jinja2.

Once this is complete, and the server has been restarted, try visiting https://<server>/_matrix/consent. If configuration has been done correctly, this should give an error "Missing string query parameter 'u'". It is now possible to manually construct URIs where users can give their consent.

Constructing the consent URI

It may be useful to manually construct the "consent URI" for a given user - for
instance, in order to send them an email asking them to consent. To do this,
take the base `https://<server>/_matrix/consent` URL and add the following
query parameters:

 * `u`: the user id of the user. This can either be a full MXID
   (`@user:server.com`) or just the localpart (`user`).

 * `h`: hex-encoded HMAC-SHA256 of `u` using the `form_secret` as a key. It is
   possible to calculate this on the commandline with something like:

   ```bash
   echo -n '<user>' | openssl sha256 -hmac '<form_secret>'
   ```

   This should result in a URI which looks something like:
   `https://<server>/_matrix/consent?u=<user>&h=68a152465a4d...`.


Sending users a server notice asking them to agree to the policy
----------------------------------------------------------------

It is possible to configure Synapse to send a [server
notice](server_notices.md) to anybody who has not yet agreed to the current
version of the policy. To do so:

 * ensure that the consent resource is configured, as in the previous section

 * ensure that server notices are configured, as in [server_notices.md].

 * Add `server_notice_content` under `user_consent` in `homeserver.yaml`. For
   example:

   ```yaml
   user_consent:
     server_notice_content:
       msgtype: m.text
       body: >-
         Please give your consent to the privacy policy at %(consent_uri)s.
   ```

   Synapse automatically replaces the placeholder `%(consent_uri)s` with the
   consent uri for that user.

Blocking users from using the server until they agree to the policy
-------------------------------------------------------------------

Synapse can be configured to block any attempts to join rooms or send messages
until the user has given their agreement to the policy. (Joining the server
notices room is exempted from this).

To enable this, add `block_events_error` under `user_consent`. For example:

```
user_consent:
  block_events_error: >-
    You can't send any messages until you consent to the privacy policy at
    %(consent_uri)s.
```

Synapse automatically replaces the placeholder `%(consent_uri)s` with the
consent uri for that user.