[feature] Read + Write tombstones for deleted Actors

go.mod

@@ -6,6 +6,7 @@ require (
 	codeberg.org/gruf/go-bytesize v1.0.0
 	codeberg.org/gruf/go-byteutil v1.0.2
 	codeberg.org/gruf/go-cache/v2 v2.1.4
+	codeberg.org/gruf/go-cache/v3 v3.1.6
 	codeberg.org/gruf/go-debug v1.2.0
 	codeberg.org/gruf/go-errors/v2 v2.0.2
 	codeberg.org/gruf/go-kv v1.5.2
@@ -65,9 +66,12 @@ require (
 	codeberg.org/gruf/go-fastcopy v1.1.1 // indirect
 	codeberg.org/gruf/go-fastpath v1.0.3 // indirect
 	codeberg.org/gruf/go-hashenc v1.0.2 // indirect
+	codeberg.org/gruf/go-mangler v1.1.1 // indirect
+	codeberg.org/gruf/go-maps v1.0.3 // indirect
 	codeberg.org/gruf/go-pools v1.1.0 // indirect
 	codeberg.org/gruf/go-sched v1.1.1 // indirect
 	github.com/aymerick/douceur v0.2.0 // indirect
+	github.com/cespare/xxhash v1.1.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dsoprea/go-exif/v3 v3.0.0-20210625224831-a6301f85c82b // indirect
 	github.com/dsoprea/go-iptc v0.0.0-20200610044640-bc9ca208b413 // indirect

go.sum

@@ -71,6 +71,8 @@ codeberg.org/gruf/go-byteutil v1.0.2 h1:OesVyK5VKWeWdeDR00zRJ+Oy8hjXx1pBhn7WVvcZ
 codeberg.org/gruf/go-byteutil v1.0.2/go.mod h1:cWM3tgMCroSzqoBXUXMhvxTxYJp+TbCr6ioISRY5vSU=
 codeberg.org/gruf/go-cache/v2 v2.1.4 h1:r+6wJiTHZn0qqf+p1VtAjGOgXXJl7s8txhPIwoSMZtI=
 codeberg.org/gruf/go-cache/v2 v2.1.4/go.mod h1:j7teiz814lG0PfSfnUs+6HA+2/jcjTAR71Ou3Wbt2Xk=
+codeberg.org/gruf/go-cache/v3 v3.1.6 h1:LMpQoLRoGTH64WyLCew6wMVqC3Vzve09MCYbt5c0WR4=
+codeberg.org/gruf/go-cache/v3 v3.1.6/go.mod h1:h6im2UVGdrGtNt4IVKARVeoW4kAdok5ts7CbH15UWXs=
 codeberg.org/gruf/go-debug v1.2.0 h1:WBbTMnK1ArFKUmgv04aO2JiC/daTOB8zQGi521qb7OU=
 codeberg.org/gruf/go-debug v1.2.0/go.mod h1:N+vSy9uJBQgpQcJUqjctvqFz7tBHJf+S/PIjLILzpLg=
 codeberg.org/gruf/go-errors/v2 v2.0.0/go.mod h1:ZRhbdhvgoUA3Yw6e56kd9Ox984RrvbEFC2pOXyHDJP4=
@@ -87,6 +89,10 @@ codeberg.org/gruf/go-kv v1.5.2 h1:B0RkAXLUXYn3Za1NzTXOcUvAc+JUC2ZadTMkCUDa0mc=
 codeberg.org/gruf/go-kv v1.5.2/go.mod h1:al6ASW/2CbGqz2YcM8B00tvWnVi1bU1CH3HYs5tZxo4=
 codeberg.org/gruf/go-logger/v2 v2.2.1 h1:RP2u059EQKTBFV3cN8X6xDxNk2RkzqdgXGKflKqB7Oc=
 codeberg.org/gruf/go-logger/v2 v2.2.1/go.mod h1:m/vBfG5jNUmYXI8Hg9aVSk7Pn8YgEBITQB/B/CzdRss=
+codeberg.org/gruf/go-mangler v1.1.1 h1:Ci56Le8PKrfESTNYjIZu3AoqAf/O2mX8BTWC6EuN7HA=
+codeberg.org/gruf/go-mangler v1.1.1/go.mod h1:z6nL/uyp1AnEFPMD7YO3J/kQTY6fBPlIjwhqBMyPExo=
+codeberg.org/gruf/go-maps v1.0.3 h1:VDwhnnaVNUIy5O93CvkcE2IZXnMB1+IJjzfop9V12es=
+codeberg.org/gruf/go-maps v1.0.3/go.mod h1:D5LNDxlC9rsDuVQVM6JObaVGAdHB6g2dTdOdkh1aXWA=
 codeberg.org/gruf/go-mutexes v1.1.4 h1:HWaIZavPL92SBJxNOlIXAmAT5CB2hAs72/lBN31jnzM=
 codeberg.org/gruf/go-mutexes v1.1.4/go.mod h1:1j/6/MBeBQUedAtAtysLLnBKogfOZAxdym0E3wlaBD8=
 codeberg.org/gruf/go-pools v1.1.0 h1:LbYP24eQLl/YI1fSU2pafiwhGol1Z1zPjRrMsXpF88s=
@@ -102,6 +108,7 @@ github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/Masterminds/semver/v3 v3.1.1 h1:hLg3sBzpNErnxhQtUy/mmLR2I9foDujNK030IGemrRc=
 github.com/Masterminds/semver/v3 v3.1.1/go.mod h1:VPu/7SZ7ePZ3QOrcuXROw5FAcLl4a0cBrbBpGY/8hQs=
+github.com/OneOfOne/xxhash v1.2.2 h1:KMrpdQIwFcEqXDklaen+P1axHaj9BSKzvpUUfnHldSE=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/ajg/form v1.5.1 h1:t9c7v8JUKu/XxOGBU0yjNpaMloxGEJhUkqFRq0ibGeU=
 github.com/ajg/form v1.5.1/go.mod h1:uL1WgH+h2mgNtvBq0339dVnzXdBETtL2LeUXaIv25UY=
@@ -113,6 +120,7 @@ github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd3
 github.com/buckket/go-blurhash v1.1.0 h1:X5M6r0LIvwdvKiUtiNcRL2YlmOfMzYobI3VCKCZc9Do=
 github.com/buckket/go-blurhash v1.1.0/go.mod h1:aT2iqo5W9vu9GpyoLErKfTHwgODsZp3bQfXjXJUxNb8=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cheekybits/is v0.0.0-20150225183255-68e9c0620927/go.mod h1:h/aW8ynjgkuj+NQRlZcDbAbM1ORAbXjXX77sX7T289U=
@@ -129,6 +137,7 @@ github.com/cncf/xds/go v0.0.0-20210805033703-aa0b78936158/go.mod h1:eXthEFrGJvWH
 github.com/cncf/xds/go v0.0.0-20210922020428-25de7278fc84/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211001041855-01bcc9b48dfe/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
+github.com/cnf/structhash v0.0.0-20201127153200-e1b16c1ebc08 h1:ox2F0PSMlrAAiAdknSRMDrAr8mfxPCfSZolH+/qQnyQ=
 github.com/cockroachdb/apd v1.1.0 h1:3LFP3629v+1aKXU5Q37mxmRxX/pIu1nijXydLShEq5I=
 github.com/cockroachdb/apd v1.1.0/go.mod h1:8Sl8LxpKi29FqWXR16WEFZRNSz3SoPzUzeMeY4+DwBQ=
 github.com/coreos/go-oidc/v3 v3.4.0 h1:xz7elHb/LDwm/ERpwHd+5nb7wFHL32rsr6bBOgaeu6g=
@@ -185,6 +194,7 @@ github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4
 github.com/fsnotify/fsnotify v1.5.4/go.mod h1:OVB6XrOHzAwXMpEM7uPOzcehqUV2UqJxmVXmkdnm1bU=
 github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
 github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
+github.com/fxamacker/cbor v1.5.1 h1:XjQWBgdmQyqimslUh5r4tUGmoqzHmBFQOImkWGi2awg=
 github.com/gavv/httpexpect v2.0.0+incompatible h1:1X9kcRshkSKEjNJJxX9Y9mQ5BRfbxU5kORdjhlA1yX8=
 github.com/gavv/httpexpect v2.0.0+incompatible/go.mod h1:x+9tiU1YnrOvnB725RkpoLv1M62hOWzwo5OXotisrKc=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
@@ -462,6 +472,7 @@ github.com/minio/minio-go/v7 v7.0.43 h1:14Q4lwblqTdlAmba05oq5xL0VBLHi06zS4yLnIkz
 github.com/minio/minio-go/v7 v7.0.43/go.mod h1:nCrRzjoSUQh8hgKKtu3Y708OLvRLtuASMg2/nvmbarw=
 github.com/minio/sha256-simd v1.0.0 h1:v1ta+49hkWZyvaKwrQB8elexRqm6Y0aMLjCNsrYxo6g=
 github.com/minio/sha256-simd v1.0.0/go.mod h1:OuYzVNI5vcoYIAmbIvHPl3N3jUzVedXbKy5RFepssQM=
+github.com/mitchellh/hashstructure/v2 v2.0.2 h1:vGKWl0YJqUNxE8d+h8f6NJLcCJrgbhC4NcD46KavDd4=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -526,6 +537,7 @@ github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykE
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
 github.com/smartystreets/goconvey v1.6.4 h1:fv0U8FUIMPNf1L9lnHLvLhgicrIVChEkdzIKYqbNC9s=
 github.com/smartystreets/goconvey v1.6.4/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
+github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72 h1:qLC7fQah7D6K1B0ujays3HV9gkFtllcxhzImRR7ArPQ=
 github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
 github.com/spf13/afero v1.9.2 h1:j49Hj62F0n+DaZ1dDCvhABaPNSGNkt32oRFxI33IEMw=
 github.com/spf13/afero v1.9.2/go.mod h1:iUV7ddyEEZPO5gA3zD4fJt6iStLlL+Lg4m2cihcDf8Y=
@@ -612,6 +624,7 @@ github.com/vmihailenco/tagparser/v2 v2.0.0 h1:y09buUbR+b5aycVFQs/g70pqKVZNBmxwAh
 github.com/vmihailenco/tagparser/v2 v2.0.0/go.mod h1:Wri+At7QHww0WTrCBeu4J6bNtoV6mEfg5OIWRZA9qds=
 github.com/wagslane/go-password-validator v0.3.0 h1:vfxOPzGHkz5S146HDpavl0cw1DSVP061Ry2PX0/ON6I=
 github.com/wagslane/go-password-validator v0.3.0/go.mod h1:TI1XJ6T5fRdRnHqHt14pvy1tNVnrwe7m3/f1f2fDphQ=
+github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f h1:J9EGpcZtP0E/raorCMxlFGSTBrsSlaDGf3jU/qvAE2c=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2zxlSyiKSe5eX1tZViRH5QA0qijqEDrYZiPEAiq3wU=
 github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 h1:EzJWgHovont7NscjpAxXsDA8S8BMYve8Y5+7cuRE7R0=

internal/db/bundb/bundb.go

@@ -88,6 +88,7 @@ type DBService struct {
 	db.Status
 	db.Timeline
 	db.User
+	db.Tombstone
 	conn *DBConn
 }
 
@@ -181,12 +182,16 @@ func NewBunDBService(ctx context.Context) (db.DB, error) {
 	status := &statusDB{conn: conn, cache: cache.NewStatusCache()}
 	emoji := &emojiDB{conn: conn, cache: cache.NewEmojiCache()}
 	timeline := &timelineDB{conn: conn}
+	tombstone := &tombstoneDB{conn: conn}
 
 	// Setup DB cross-referencing
 	accounts.status = status
 	status.accounts = accounts
 	timeline.status = status
 
+	// Initialize db structs
+	tombstone.init()
+
 	ps := &DBService{
 		Account: accounts,
 		Admin: &adminDB{
@@ -228,7 +233,8 @@ func NewBunDBService(ctx context.Context) (db.DB, error) {
 			conn:  conn,
 			cache: userCache,
 		},
-		conn: conn,
+		Tombstone: tombstone,
+		conn:      conn,
 	}
 
 	// we can confidently return this useable service now

internal/db/bundb/migrations/20221108142419_create_account_tombstones.go

@@ -0,0 +1,57 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   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 migrations
+
+import (
+	"context"
+
+	gtsmodel "github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/uptrace/bun"
+)
+
+func init() {
+	up := func(ctx context.Context, db *bun.DB) error {
+		return db.RunInTx(ctx, nil, func(ctx context.Context, tx bun.Tx) error {
+			if _, err := tx.NewCreateTable().Model(&gtsmodel.Tombstone{}).IfNotExists().Exec(ctx); err != nil {
+				return err
+			}
+
+			if _, err := tx.
+				NewCreateIndex().
+				Model(&gtsmodel.Tombstone{}).
+				Index("tombstone_uri_idx").
+				Column("uri").
+				Exec(ctx); err != nil {
+				return err
+			}
+
+			return nil
+		})
+	}
+
+	down := func(ctx context.Context, db *bun.DB) error {
+		return db.RunInTx(ctx, nil, func(ctx context.Context, tx bun.Tx) error {
+			return nil
+		})
+	}
+
+	if err := Migrations.Register(up, down); err != nil {
+		panic(err)
+	}
+}

internal/db/bundb/tombstone.go

@@ -0,0 +1,101 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   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 bundb
+
+import (
+	"context"
+	"time"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/uptrace/bun"
+
+	"codeberg.org/gruf/go-cache/v3/result"
+)
+
+type tombstoneDB struct {
+	conn  *DBConn
+	cache *result.Cache[*gtsmodel.Tombstone]
+}
+
+func (t *tombstoneDB) init() {
+	// Initialize tombstone result cache
+	t.cache = result.NewSized([]string{
+		"ID",
+		"URI",
+	}, func(t1 *gtsmodel.Tombstone) *gtsmodel.Tombstone {
+		t2 := new(gtsmodel.Tombstone)
+		*t2 = *t1
+		return t2
+	}, 1000)
+
+	// Set cache TTL and start sweep routine
+	t.cache.SetTTL(time.Minute*5, false)
+	t.cache.Start(time.Second * 10)
+}
+
+func (t *tombstoneDB) GetTombstoneByURI(ctx context.Context, uri string) (*gtsmodel.Tombstone, db.Error) {
+	return t.cache.Load("URI", func() (*gtsmodel.Tombstone, error) {
+		var tomb gtsmodel.Tombstone
+
+		q := t.conn.
+			NewSelect().
+			Model(&tomb).
+			Where("? = ?", bun.Ident("tombstone.uri"), uri)
+
+		if err := q.Scan(ctx); err != nil {
+			return nil, t.conn.ProcessError(err)
+		}
+
+		return &tomb, nil
+	}, uri)
+}
+
+func (t *tombstoneDB) TombstoneExistsWithURI(ctx context.Context, uri string) (bool, db.Error) {
+	tomb, err := t.GetTombstoneByURI(ctx, uri)
+	if err == db.ErrNoEntries {
+		err = nil
+	}
+	return (tomb != nil), err
+}
+
+func (t *tombstoneDB) PutTombstone(ctx context.Context, tombstone *gtsmodel.Tombstone) db.Error {
+	return t.cache.Store(tombstone, func() error {
+		_, err := t.conn.
+			NewInsert().
+			Model(tombstone).
+			Exec(ctx)
+		return t.conn.ProcessError(err)
+	})
+}
+
+func (t *tombstoneDB) DeleteTombstone(ctx context.Context, id string) db.Error {
+	if _, err := t.conn.
+		NewDelete().
+		TableExpr("? AS ?", bun.Ident("tombstones"), bun.Ident("tombstone")).
+		Where("? = ?", bun.Ident("tombstone.id"), id).
+		Exec(ctx); err != nil {
+		return t.conn.ProcessError(err)
+	}
+
+	// Invalidate from cache by ID
+	t.cache.Invalidate("ID", id)
+
+	return nil
+}

internal/db/db.go

@@ -45,6 +45,7 @@ type DB interface {
 	Status
 	Timeline
 	User
+	Tombstone
 
 	/*
 		USEFUL CONVERSION FUNCTIONS

internal/db/tombstone.go

@@ -0,0 +1,40 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   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 db
+
+import (
+	"context"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// Tombstone contains functionality for storing + retrieving tombstones for remote AP Activities + Objects.
+type Tombstone interface {
+	// GetTombstoneByURI attempts to fetch a tombstone by the given URI.
+	GetTombstoneByURI(ctx context.Context, uri string) (*gtsmodel.Tombstone, Error)
+
+	// TombstoneExistsWithURI returns true if a tombstone with the given URI exists.
+	TombstoneExistsWithURI(ctx context.Context, uri string) (bool, Error)
+
+	// PutTombstone creates a new tombstone in the database.
+	PutTombstone(ctx context.Context, tombstone *gtsmodel.Tombstone) Error
+
+	// DeleteTombstone deletes a tombstone with the given ID.
+	DeleteTombstone(ctx context.Context, id string) Error
+}

internal/federation/authenticate.go

@@ -37,6 +37,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/transport"
 )
 
 /*
@@ -201,17 +202,43 @@ func (f *federator) AuthenticateFederatedRequest(ctx context.Context, requestedU
 		// REMOTE ACCOUNT REQUEST WITHOUT KEY CACHED LOCALLY
 		// the request is remote and we don't have the public key yet,
 		// so we need to authenticate the request properly by dereferencing the remote key
+		gone, err := f.CheckGone(ctx, requestingPublicKeyID)
+		if err != nil {
+			errWithCode := gtserror.NewErrorInternalError(fmt.Errorf("error checking for tombstone for %s: %s", requestingPublicKeyID, err))
+			log.Debug(errWithCode)
+			return nil, errWithCode
+		}
+
+		if gone {
+			errWithCode := gtserror.NewErrorGone(fmt.Errorf("account with public key %s is gone", requestingPublicKeyID))
+			log.Debug(errWithCode)
+			return nil, errWithCode
+		}
+
 		log.Tracef("proceeding with dereference for uncached public key %s", requestingPublicKeyID)
-		transport, err := f.transportController.NewTransportForUsername(ctx, requestedUsername)
+		trans, err := f.transportController.NewTransportForUsername(ctx, requestedUsername)
 		if err != nil {
 			errWithCode := gtserror.NewErrorInternalError(fmt.Errorf("error creating transport for %s: %s", requestedUsername, err))
 			log.Debug(errWithCode)
 			return nil, errWithCode
 		}
 
 		// The actual http call to the remote server is made right here in the Dereference function.
-		b, err := transport.Dereference(ctx, requestingPublicKeyID)
+		b, err := trans.Dereference(ctx, requestingPublicKeyID)
 		if err != nil {
+			if errors.Is(err, transport.ErrGone) {
+				// if we get a 410 error it means the account that owns this public key has been deleted;
+				// we should add a tombstone to our database so that we can avoid trying to deref it in future
+				if err := f.HandleGone(ctx, requestingPublicKeyID); err != nil {
+					errWithCode := gtserror.NewErrorInternalError(fmt.Errorf("error marking account with public key %s as gone: %s", requestingPublicKeyID, err))
+					log.Debug(errWithCode)
+					return nil, errWithCode
+				}
+				errWithCode := gtserror.NewErrorGone(fmt.Errorf("account with public key %s is gone", requestingPublicKeyID))
+				log.Debug(errWithCode)
+				return nil, errWithCode
+			}
+
 			errWithCode := gtserror.NewErrorUnauthorized(fmt.Errorf("error dereferencing public key %s: %s", requestingPublicKeyID, err))
 			log.Debug(errWithCode)
 			return nil, errWithCode