[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

1 files changed, 10 insertions, 0 deletions

diff --git a/internal/cache/invalidate.go b/internal/cache/invalidate.go
index 42d7b7399..555c73cd7 100644
--- a/internal/cache/invalidate.go
+++ b/internal/cache/invalidate.go
@@ -283,6 +283,11 @@ func (c *Caches) OnInvalidateStatusFave(fave *gtsmodel.StatusFave) {
 	c.DB.StatusFaveIDs.Invalidate(fave.StatusID)
 }
 
+func (c *Caches) OnInvalidateToken(token *gtsmodel.Token) {
+	// Invalidate token's push subscription.
+	c.DB.WebPushSubscription.Invalidate("ID", token.ID)
+}
+
 func (c *Caches) OnInvalidateUser(user *gtsmodel.User) {
 	// Invalidate local account ID cached visibility.
 	c.Visibility.Invalidate("ItemID", user.AccountID)
@@ -296,3 +301,8 @@ func (c *Caches) OnInvalidateUserMute(mute *gtsmodel.UserMute) {
 	// Invalidate source account's user mute lists.
 	c.DB.UserMuteIDs.Invalidate(mute.AccountID)
 }
+
+func (c *Caches) OnInvalidateWebPushSubscription(subscription *gtsmodel.WebPushSubscription) {
+	// Invalidate source account's Web Push subscription list.
+	c.DB.WebPushSubscriptionIDs.Invalidate(subscription.AccountID)
+}