Address feedback and generate access_token on the client side

docs/raw/push-notification-server.md

@@ -31,8 +31,8 @@ title: 16/PUSH-NOTIFICATION-SERVER
   - [Protobuf description](#protobuf-description)
     - [PushNotificationRegister](#pushnotificationregister)
     - [PushNotificationPreferences](#pushnotificationpreferences)
-    - [PushNotificationDeviceToken](#pushnotificationdevicetoken)
     - [PushNotificationOptions](#pushnotificationoptions)
+    - [PushNotificationFilterSettings](#pushnotificationfiltersettings)
     - [PushNotificationRegistrationResponse](#pushnotificationregistrationresponse)
     - [ContactCodeAdvertisement](#contactcodeadvertisement)
     - [PushNotificationAdvertisementInfo](#pushnotificationadvertisementinfo)
@@ -110,14 +110,14 @@ The content of the message MUST contain the following [protobuf record](https://
 
 ```protobuf
 
-message PushNotificationOptions {
+message PushNotificationFilterSettings {
   boolean enabled = 1;
   repeated string allowed_user_list = 2;
   repeated string blocked_user_list = 3;
   repeated string blocked_chat_list = 4;
 }
 
-message PushNotificationDeviceToken {
+message PushNotificationOptions {
   enum TokenType {
     UNKNOWN_TOKEN_TYPE = 0;
     APN_TOKEN = 1;
@@ -126,13 +126,14 @@ message PushNotificationDeviceToken {
   TokenType token_type = 1;
   string token = 2;
   string installation_id = 3;
-  PushNotificationPreferences preferences = 4;
+  PushNotificationFilterSettings filter_settings = 4;
 }
 
 message PushNotificationPreferences {
-  repeated DeviceToken device_tokens = 1;
+  repeated PushNotificationOptions options = 1;
   uint version = 2;
   boolean unregister = 3;
+  string access_token = 4;
 }
 
 message PushNotificationRegister {
@@ -148,27 +149,26 @@ A push notification server will handle the message according to the following ru
 - it MUST verify that `token` is non empty
 - it MUST verify that `installation_id` is non empty
 - it MUST verify that `version` is non-zero and greater than the currently stored version for the public key of the sender, if any
-- it MUST verify that `device_tokens` is non empty
+- it MUST verify that `options` is non empty
+- it MUST verify that `access_token` is a 36 characters string
 
 If `signature` does not match the public key of the sender, the message MUST be discarded.
 
 If `token_type` is not supported, a response MUST be sent with `error` set to 
 `UNSUPPORTED_TOKEN_TYPE`.
 
-If `token`,`installation_id`,`device_tokens`,`version` are empty, a response MUST
+If `token`,`installation_id`,`options`,`version` are empty, a response MUST
 be sent with `error` set to `MALFORMED_MESSAGE`.
 
 If the `version` is equal or less than the currently stored version, a response MUST
 be sent with `error` set to `VERSION_MISMATCH`.
 
 If any other error occurs the `error` should be set to `INTERNAL_ERROR`.
 
-If the request is successful, an access token MUST be generated and sent back to the client
 with `success` set to `true`.
 
 Otherwise a response MUST be sent with `success` set to `false`.
 
-It is RECOMMENDED to use a randomly generated string for `access_token` of at least 36 characters.
 
 `request_id` should be set to the `SHA3-256` of the signature sent by the client.
 
@@ -182,7 +182,6 @@ message PushNotificationRegistrationResponse {
   ErrorType error = 2;
   bytes request_id = 3;
   PushNotificationPreferences preferences = 4;
-  string access_token = 5;
 
   enum ErrorType {
     UNKNOWN_ERROR_TYPE = 0;
@@ -453,31 +452,32 @@ A `PushNotificationRegister` is used to register with a Push Notification server
 
 A push notification preferences message describes the push notification options and tokens for all the devices associated with `PublicKeyClient`.
 
-`device_tokens`: a list of `PushNotificationPreferences`, one for each device owned by the user.
+`options`: a list of `PushNotificationOptions`, one for each device owned by the user.
 `version`: an monotonically increasing number identifying the current `PushNotificationPreferences`. Any time anything is changed in the record it MUST be increased by the client, otherwise the request will not be accepted.
 `unregister`: whether the account should be unregistered
+`access_token`: the access token that will be given to clients to send push notifications
 
 #### Data disclosed
 
 - Number of devices with push notifications enabled for a given public key
 - The times a push notification record has been modified by the user
 
-### PushNotificationDeviceToken
+### PushNotificationOptions
 
-`PushNotificationDeviceToken` represent the token and preferences for a given device.
+`PushNotificationOptions` represent the token and preferences for a given device.
 
 `token_type`: the type of token. Currently supported is `APN_TOKEN` for Apple Push 
 Notification service and `FIREBASE_TOKEN` for `Firebase`.
 `token`: the actual push notification token sent by `Firebase` or `APN`
 `installation_id`: the [`installation_id`](./2-account.md) of the device
-`preferences`: the push notification preferences for this device.
+`filter_setttings`: the push notification filters for this device.
 
 #### Data disclosed
 
 - Type of device owned by a given user
 - The `FIREBASE` or `APN` push notification token 
 
-### PushNotificationOptions
+### PushNotificationFilterSettings
 
 [//]: (Any of these can be sha3 in order not to store it on the server)
 
@@ -499,8 +499,6 @@ in this list MUST not be issued a token.
 `error`: the error type, if any
 `request_id`: the `SHA3-256` hash of the `signature` of the request
 `preferences`: the server stored preferences in case of an error
-`access_token`: the token that needs to be used by client to send a push notification,
-in case the request is successful. This is generated by the push notification server.
 
 ### ContactCodeAdvertisement