[feature] Push notifications (#3587)

* Update push subscription API model to be Mastodon 4.0 compatible

* Add webpush-go dependency

# Conflicts:
#	go.sum

* Single-row table for storing instance's VAPID key pair

* Generate VAPID key pair during startup

* Add VAPID public key to instance info API

* Return VAPID public key when registering an app

* Store Web Push subscriptions in DB

* Add Web Push sender (similar to email sender)

* Add no-op push senders to most processor tests

* Test Web Push notifications from workers

* Delete Web Push subscriptions when account is deleted

* Implement push subscription API

* Linter fixes

* Update Swagger

* Fix enum to int migration

* Fix GetVAPIDKeyPair

* Create web push subscriptions table with indexes

* Log Web Push server error messages

* Send instance URL as Web Push JWT subject

* Accept any 2xx code as a success

* Fix malformed VAPID sub claim

* Use packed notification flags

* Remove unused date columns

* Add notification type for update notifications

Not used yet

* Make GetVAPIDKeyPair idempotent

and remove PutVAPIDKeyPair

* Post-rebase fixes

* go mod tidy

* Special-case 400 errors other than 408/429

Most client errors should remove the subscription.

* Improve titles, trim body to reasonable length

* Disallow cleartext HTTP for Web Push servers

* Fix lint

* Remove redundant index on unique column

Also removes redundant unique and notnull tags on ID column since these are implied by pk

* Make realsender.go more readable

* Use Tobi's style for wrapping errors

* Restore treating all 5xx codes as temporary problems

* Always load target account settings

* Stub `policy` and `standard`

* webpush.Sender: take type converter as ctor param

* Move webpush.MockSender and noopSender into testrig

4 files changed, 219 insertions, 44 deletions

diff --git a/internal/api/model/instancev2.go b/internal/api/model/instancev2.go
index 982ed0c63..b3d11dee2 100644
--- a/internal/api/model/instancev2.go
+++ b/internal/api/model/instancev2.go
@@ -174,6 +174,8 @@ type InstanceV2Configuration struct {
 	Emojis InstanceConfigurationEmojis `json:"emojis"`
 	// True if instance is running with OIDC as auth/identity backend, else omitted.
 	OIDCEnabled bool `json:"oidc_enabled,omitempty"`
+	// Instance VAPID configuration.
+	VAPID InstanceV2ConfigurationVAPID `json:"vapid"`
 }
 
 // Information about registering for this instance.
@@ -204,3 +206,11 @@ type InstanceV2Contact struct {
 	// Key/value not present if no contact account set.
 	Account *Account `json:"account,omitempty"`
 }
+
+// InstanceV2ConfigurationVAPID holds the instance's VAPID configuration.
+//
+// swagger:model instanceV2ConfigurationVAPID
+type InstanceV2ConfigurationVAPID struct {
+	// The instance's VAPID public key, Base64-encoded.
+	PublicKey string `json:"public_key"`
+}
diff --git a/internal/api/model/pushsubscription.go b/internal/api/model/pushsubscription.go
deleted file mode 100644
index 1e7708d94..000000000
--- a/internal/api/model/pushsubscription.go
+++ /dev/null
@@ -1,44 +0,0 @@
-// GoToSocial
-// Copyright (C) GoToSocial Authors admin@gotosocial.org
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Affero General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU Affero General Public License for more details.
-//
-// You should have received a copy of the GNU Affero General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-package model
-
-// PushSubscription represents a subscription to the push streaming server.
-type PushSubscription struct {
-	// The id of the push subscription in the database.
-	ID string `json:"id"`
-	// Where push alerts will be sent to.
-	Endpoint string `json:"endpoint"`
-	// The streaming server's VAPID key.
-	ServerKey string `json:"server_key"`
-	// Which alerts should be delivered to the endpoint.
-	Alerts *PushSubscriptionAlerts `json:"alerts"`
-}
-
-// PushSubscriptionAlerts represents the specific alerts that this push subscription will give.
-type PushSubscriptionAlerts struct {
-	// Receive a push notification when someone has followed you?
-	Follow bool `json:"follow"`
-	// Receive a push notification when a status you created has been favourited by someone else?
-	Favourite bool `json:"favourite"`
-	// Receive a push notification when someone else has mentioned you in a status?
-	Mention bool `json:"mention"`
-	// Receive a push notification when a status you created has been boosted by someone else?
-	Reblog bool `json:"reblog"`
-	// Receive a push notification when a poll you voted in or created has ended?
-	Poll bool `json:"poll"`
-}
diff --git a/internal/api/model/webpushnotification.go b/internal/api/model/webpushnotification.go
new file mode 100644
index 000000000..5d7a593fc
--- /dev/null
+++ b/internal/api/model/webpushnotification.go
@@ -0,0 +1,52 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package model
+
+// WebPushNotification represents a notification summary delivered to the client by the Web Push server.
+// It does not contain an entire Notification, just the NotificationID and some preview information.
+// It is not used in the client API directly, but is included in the API doc for decoding Web Push notifications.
+//
+// swagger:model webPushNotification
+type WebPushNotification struct {
+	// NotificationID is the Notification.ID of the referenced Notification.
+	NotificationID string `json:"notification_id"`
+
+	// NotificationType is the Notification.Type of the referenced Notification.
+	NotificationType string `json:"notification_type"`
+
+	// Title is a title for the notification,
+	// generally describing an action taken by a user.
+	Title string `json:"title"`
+
+	// Body is a preview of the notification body,
+	// such as the first line of a status's CW or text,
+	// or the first line of an account bio.
+	Body string `json:"body"`
+
+	// Icon is an image URL that can be displayed with the notification,
+	// normally the account's avatar.
+	Icon string `json:"icon"`
+
+	// PreferredLocale is a BCP 47 language tag for the receiving user's locale.
+	PreferredLocale string `json:"preferred_locale"`
+
+	// AccessToken is the access token associated with the Web Push subscription.
+	// I don't know why this is sent, given that the client should know that already,
+	// but Feditext does use it.
+	AccessToken string `json:"access_token"`
+}
diff --git a/internal/api/model/webpushsubscription.go b/internal/api/model/webpushsubscription.go
new file mode 100644
index 000000000..a28bb7294
--- /dev/null
+++ b/internal/api/model/webpushsubscription.go
@@ -0,0 +1,157 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package model
+
+// WebPushSubscription represents a subscription to a Web Push server.
+//
+// swagger:model webPushSubscription
+type WebPushSubscription struct {
+	// The id of the push subscription in the database.
+	ID string `json:"id"`
+
+	// Where push alerts will be sent to.
+	Endpoint string `json:"endpoint"`
+
+	// The streaming server's VAPID public key.
+	ServerKey string `json:"server_key"`
+
+	// Which alerts should be delivered to the endpoint.
+	Alerts WebPushSubscriptionAlerts `json:"alerts"`
+
+	// Which accounts should generate notifications.
+	Policy WebPushNotificationPolicy `json:"policy"`
+
+	// Whether the subscription uses RFC or pre-RFC Web Push standards.
+	// For GotoSocial, this is always true.
+	Standard bool `json:"standard"`
+}
+
+// WebPushSubscriptionAlerts represents the specific events that this Web Push subscription will receive.
+//
+// swagger:model webPushSubscriptionAlerts
+type WebPushSubscriptionAlerts struct {
+	// Receive a push notification when someone has followed you?
+	Follow bool `json:"follow"`
+
+	// Receive a push notification when someone has requested to follow you?
+	FollowRequest bool `json:"follow_request"`
+
+	// Receive a push notification when a status you created has been favourited by someone else?
+	Favourite bool `json:"favourite"`
+
+	// Receive a push notification when someone else has mentioned you in a status?
+	Mention bool `json:"mention"`
+
+	// Receive a push notification when a status you created has been boosted by someone else?
+	Reblog bool `json:"reblog"`
+
+	// Receive a push notification when a poll you voted in or created has ended?
+	Poll bool `json:"poll"`
+
+	// Receive a push notification when a subscribed account posts a status?
+	Status bool `json:"status"`
+
+	// Receive a push notification when a status you interacted with has been edited?
+	Update bool `json:"update"`
+
+	// Receive a push notification when a new user has signed up?
+	AdminSignup bool `json:"admin.sign_up"`
+
+	// Receive a push notification when a new report has been filed?
+	AdminReport bool `json:"admin.report"`
+
+	// Receive a push notification when a fave is pending?
+	PendingFavourite bool `json:"pending.favourite"`
+
+	// Receive a push notification when a reply is pending?
+	PendingReply bool `json:"pending.reply"`
+
+	// Receive a push notification when a boost is pending?
+	PendingReblog bool `json:"pending.reblog"`
+}
+
+// WebPushSubscriptionCreateRequest captures params for creating or replacing a Web Push subscription.
+//
+// swagger:ignore
+type WebPushSubscriptionCreateRequest struct {
+	Subscription *WebPushSubscriptionRequestSubscription `form:"-" json:"subscription"`
+
+	SubscriptionEndpoint   *string `form:"subscription[endpoint]" json:"-"`
+	SubscriptionKeysAuth   *string `form:"subscription[keys][auth]" json:"-"`
+	SubscriptionKeysP256dh *string `form:"subscription[keys][p256dh]" json:"-"`
+
+	WebPushSubscriptionUpdateRequest
+}
+
+// WebPushSubscriptionRequestSubscription is the part of a Web Push subscription that is fixed at creation.
+//
+// swagger:ignore
+type WebPushSubscriptionRequestSubscription struct {
+	// Endpoint is the URL to which Web Push notifications will be sent.
+	Endpoint string `json:"endpoint"`
+
+	Keys WebPushSubscriptionRequestSubscriptionKeys `json:"keys"`
+}
+
+// WebPushSubscriptionRequestSubscriptionKeys is the part of a Web Push subscription that contains auth secrets.
+//
+// swagger:ignore
+type WebPushSubscriptionRequestSubscriptionKeys struct {
+	// Auth is the auth secret, a Base64 encoded string of 16 bytes of random data.
+	Auth string `json:"auth"`
+
+	// P256dh is the user agent public key, a Base64 encoded string of a public key from an ECDH keypair using the prime256v1 curve.
+	P256dh string `json:"p256dh"`
+}
+
+// WebPushSubscriptionUpdateRequest captures params for updating a Web Push subscription.
+//
+// swagger:ignore
+type WebPushSubscriptionUpdateRequest struct {
+	Data *WebPushSubscriptionRequestData `form:"-" json:"data"`
+
+	DataAlertsFollow           *bool `form:"data[alerts][follow]" json:"-"`
+	DataAlertsFollowRequest    *bool `form:"data[alerts][follow_request]" json:"-"`
+	DataAlertsFavourite        *bool `form:"data[alerts][favourite]" json:"-"`
+	DataAlertsMention          *bool `form:"data[alerts][mention]" json:"-"`
+	DataAlertsReblog           *bool `form:"data[alerts][reblog]" json:"-"`
+	DataAlertsPoll             *bool `form:"data[alerts][poll]" json:"-"`
+	DataAlertsStatus           *bool `form:"data[alerts][status]" json:"-"`
+	DataAlertsUpdate           *bool `form:"data[alerts][update]" json:"-"`
+	DataAlertsAdminSignup      *bool `form:"data[alerts][admin.sign_up]" json:"-"`
+	DataAlertsAdminReport      *bool `form:"data[alerts][admin.report]" json:"-"`
+	DataAlertsPendingFavourite *bool `form:"data[alerts][pending.favourite]" json:"-"`
+	DataAlertsPendingReply     *bool `form:"data[alerts][pending.reply]" json:"-"`
+	DataAlertsPendingReblog    *bool `form:"data[alerts][pending.reblog]" json:"-"`
+}
+
+// WebPushSubscriptionRequestData is the part of a Web Push subscription that can be changed after creation.
+//
+// swagger:ignore
+type WebPushSubscriptionRequestData struct {
+	// Alerts selects the specific events that this Web Push subscription will receive.
+	Alerts *WebPushSubscriptionAlerts `form:"-" json:"alerts"`
+}
+
+// WebPushNotificationPolicy names sets of accounts that can generate notifications.
+type WebPushNotificationPolicy string
+
+const (
+	// WebPushNotificationPolicyAll allows all accounts to send notifications to the subscribing user.
+	WebPushNotificationPolicyAll WebPushNotificationPolicy = "all"
+)