[feature] Add `instance-stats-randomize` config option (#3718)

* [feature] Add `instance-stats-randomize` config option

* don't use cache (overkill)

13 files changed, 183 insertions, 10 deletions

diff --git a/docs/configuration/instance.md b/docs/configuration/instance.md
index cc793b7fe..fdaf324cf 100644
--- a/docs/configuration/instance.md
+++ b/docs/configuration/instance.md
@@ -138,4 +138,15 @@ instance-subscriptions-process-from: "23:00"
 # Examples: ["24h", "72h", "12h"]
 # Default: "24h" (once per day).
 instance-subscriptions-process-every: "24h"
+
+# Bool. Set this to true to randomize stats served at
+# the /api/v1|v2/instance and /nodeinfo/2.0 endpoints.
+#
+# This can be useful when you don't want bots to obtain
+# reliable information about the amount of users and
+# statuses on your instance.
+#
+# Options: [true, false]
+# Default: false
+instance-stats-randomize: false
 ```
diff --git a/example/config.yaml b/example/config.yaml
index 164eea7b2..10d7799c6 100644
--- a/example/config.yaml
+++ b/example/config.yaml
@@ -425,6 +425,17 @@ instance-subscriptions-process-from: "23:00"
 # Default: "24h" (once per day).
 instance-subscriptions-process-every: "24h"
 
+# Bool. Set this to true to randomize stats served at
+# the /api/v1|v2/instance and /nodeinfo/2.0 endpoints.
+#
+# This can be useful when you don't want bots to obtain
+# reliable information about the amount of users and
+# statuses on your instance.
+#
+# Options: [true, false]
+# Default: false
+instance-stats-randomize: false
+
 ###########################
 ##### ACCOUNTS CONFIG #####
 ###########################
diff --git a/internal/api/client/instance/instanceget.go b/internal/api/client/instance/instanceget.go
index 6690e7e98..d7a688b43 100644
--- a/internal/api/client/instance/instanceget.go
+++ b/internal/api/client/instance/instanceget.go
@@ -21,7 +21,9 @@ import (
 	"net/http"
 
 	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
 
 	"github.com/gin-gonic/gin"
 )
@@ -58,6 +60,12 @@ func (m *Module) InstanceInformationGETHandlerV1(c *gin.Context) {
 		return
 	}
 
+	if config.GetInstanceStatsRandomize() {
+		// Replace actual stats with cached randomized ones.
+		instance.Stats["user_count"] = util.Ptr(int(instance.RandomStats.TotalUsers))
+		instance.Stats["status_count"] = util.Ptr(int(instance.RandomStats.Statuses))
+	}
+
 	apiutil.JSON(c, http.StatusOK, instance)
 }
 
@@ -93,5 +101,10 @@ func (m *Module) InstanceInformationGETHandlerV2(c *gin.Context) {
 		return
 	}
 
+	if config.GetInstanceStatsRandomize() {
+		// Replace actual stats with cached randomized ones.
+		instance.Usage.Users.ActiveMonth = int(instance.RandomStats.MonthlyActiveUsers)
+	}
+
 	apiutil.JSON(c, http.StatusOK, instance)
 }
diff --git a/internal/api/model/instance.go b/internal/api/model/instance.go
index d59424fa5..aaa01d837 100644
--- a/internal/api/model/instance.go
+++ b/internal/api/model/instance.go
@@ -17,7 +17,10 @@
 
 package model
 
-import "mime/multipart"
+import (
+	"mime/multipart"
+	"time"
+)
 
 // InstanceSettingsUpdateRequest models an instance update request.
 //
@@ -148,3 +151,11 @@ type InstanceConfigurationEmojis struct {
 	// example: 51200
 	EmojiSizeLimit int `json:"emoji_size_limit"`
 }
+
+// swagger:ignore
+type RandomStats struct {
+	Statuses           int64
+	TotalUsers         int64
+	MonthlyActiveUsers int64
+	Generated          time.Time
+}
diff --git a/internal/api/model/instancev1.go b/internal/api/model/instancev1.go
index 6dedd04cc..57e32c80a 100644
--- a/internal/api/model/instancev1.go
+++ b/internal/api/model/instancev1.go
@@ -110,6 +110,13 @@ type InstanceV1 struct {
 	Terms string `json:"terms,omitempty"`
 	// Raw (unparsed) version of terms.
 	TermsRaw string `json:"terms_text,omitempty"`
+
+	// Random stats generated for the instance.
+	// Only used if `instance-stats-randomize` is true.
+	// Not serialized to the frontend.
+	//
+	// swagger:ignore
+	RandomStats `json:"-"`
 }
 
 // InstanceV1URLs models instance-relevant URLs for client application consumption.
diff --git a/internal/api/model/instancev2.go b/internal/api/model/instancev2.go
index b3d11dee2..96399ea06 100644
--- a/internal/api/model/instancev2.go
+++ b/internal/api/model/instancev2.go
@@ -74,6 +74,13 @@ type InstanceV2 struct {
 	Terms string `json:"terms,omitempty"`
 	// Raw (unparsed) version of terms.
 	TermsText string `json:"terms_text,omitempty"`
+
+	// Random stats generated for the instance.
+	// Only used if `instance-stats-randomize` is true.
+	// Not serialized to the frontend.
+	//
+	// swagger:ignore
+	RandomStats `json:"-"`
 }
 
 // Usage data for this instance.
diff --git a/internal/config/config.go b/internal/config/config.go
index 33b4553a8..807d686d5 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -90,6 +90,7 @@ type Configuration struct {
 	InstanceLanguages                 language.Languages `name:"instance-languages" usage:"BCP47 language tags for the instance. Used to indicate the preferred languages of instance residents (in order from most-preferred to least-preferred)."`
 	InstanceSubscriptionsProcessFrom  string             `name:"instance-subscriptions-process-from" usage:"Time of day from which to start running instance subscriptions processing jobs. Should be in the format 'hh:mm:ss', eg., '15:04:05'."`
 	InstanceSubscriptionsProcessEvery time.Duration      `name:"instance-subscriptions-process-every" usage:"Period to elapse between instance subscriptions processing jobs, starting from instance-subscriptions-process-from."`
+	InstanceStatsRandomize            bool               `name:"instance-stats-randomize" usage:"Set to true to randomize the stats served at api/v1/instance and api/v2/instance endpoints. Home page stats remain unchanged."`
 
 	AccountsRegistrationOpen bool `name:"accounts-registration-open" usage:"Allow anyone to submit an account signup request. If false, server will be invite-only."`
 	AccountsReasonRequired   bool `name:"accounts-reason-required" usage:"Do new account signups require a reason to be submitted on registration?"`
diff --git a/internal/config/flags.go b/internal/config/flags.go
index 6f0957c36..b0b530d0b 100644
--- a/internal/config/flags.go
+++ b/internal/config/flags.go
@@ -92,6 +92,7 @@ func (s *ConfigState) AddServerFlags(cmd *cobra.Command) {
 		cmd.Flags().StringSlice(InstanceLanguagesFlag(), cfg.InstanceLanguages.TagStrs(), fieldtag("InstanceLanguages", "usage"))
 		cmd.Flags().String(InstanceSubscriptionsProcessFromFlag(), cfg.InstanceSubscriptionsProcessFrom, fieldtag("InstanceSubscriptionsProcessFrom", "usage"))
 		cmd.Flags().Duration(InstanceSubscriptionsProcessEveryFlag(), cfg.InstanceSubscriptionsProcessEvery, fieldtag("InstanceSubscriptionsProcessEvery", "usage"))
+		cmd.Flags().Bool(InstanceStatsRandomizeFlag(), cfg.InstanceStatsRandomize, fieldtag("InstanceStatsRandomize", "usage"))
 
 		// Accounts
 		cmd.Flags().Bool(AccountsRegistrationOpenFlag(), cfg.AccountsRegistrationOpen, fieldtag("AccountsRegistrationOpen", "usage"))
diff --git a/internal/config/helpers.gen.go b/internal/config/helpers.gen.go
index 0f8ec02ce..469c46a7a 100644
--- a/internal/config/helpers.gen.go
+++ b/internal/config/helpers.gen.go
@@ -1057,6 +1057,31 @@ func SetInstanceSubscriptionsProcessEvery(v time.Duration) {
 	global.SetInstanceSubscriptionsProcessEvery(v)
 }
 
+// GetInstanceStatsRandomize safely fetches the Configuration value for state's 'InstanceStatsRandomize' field
+func (st *ConfigState) GetInstanceStatsRandomize() (v bool) {
+	st.mutex.RLock()
+	v = st.config.InstanceStatsRandomize
+	st.mutex.RUnlock()
+	return
+}
+
+// SetInstanceStatsRandomize safely sets the Configuration value for state's 'InstanceStatsRandomize' field
+func (st *ConfigState) SetInstanceStatsRandomize(v bool) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.InstanceStatsRandomize = v
+	st.reloadToViper()
+}
+
+// InstanceStatsRandomizeFlag returns the flag name for the 'InstanceStatsRandomize' field
+func InstanceStatsRandomizeFlag() string { return "instance-stats-randomize" }
+
+// GetInstanceStatsRandomize safely fetches the value for global configuration 'InstanceStatsRandomize' field
+func GetInstanceStatsRandomize() bool { return global.GetInstanceStatsRandomize() }
+
+// SetInstanceStatsRandomize safely sets the value for global configuration 'InstanceStatsRandomize' field
+func SetInstanceStatsRandomize(v bool) { global.SetInstanceStatsRandomize(v) }
+
 // GetAccountsRegistrationOpen safely fetches the Configuration value for state's 'AccountsRegistrationOpen' field
 func (st *ConfigState) GetAccountsRegistrationOpen() (v bool) {
 	st.mutex.RLock()
@@ -2699,7 +2724,7 @@ func (st *ConfigState) SetAdvancedRateLimitExceptionsParsed(v []netip.Prefix) {
 }
 
 // AdvancedRateLimitExceptionsParsedFlag returns the flag name for the 'AdvancedRateLimitExceptionsParsed' field
-func AdvancedRateLimitExceptionsParsedFlag() string { return "" }
+func AdvancedRateLimitExceptionsParsedFlag() string { return "advanced-rate-limit-exceptions-parsed" }
 
 // GetAdvancedRateLimitExceptionsParsed safely fetches the value for global configuration 'AdvancedRateLimitExceptionsParsed' field
 func GetAdvancedRateLimitExceptionsParsed() []netip.Prefix {
diff --git a/internal/processing/fedi/wellknown.go b/internal/processing/fedi/wellknown.go
index 4784b4bf7..ac92370c8 100644
--- a/internal/processing/fedi/wellknown.go
+++ b/internal/processing/fedi/wellknown.go
@@ -65,16 +65,30 @@ func (p *Processor) NodeInfoRelGet(ctx context.Context) (*apimodel.WellKnownResp
 
 // NodeInfoGet returns a node info struct in response to a node info request.
 func (p *Processor) NodeInfoGet(ctx context.Context) (*apimodel.Nodeinfo, gtserror.WithCode) {
-	host := config.GetHost()
+	var (
+		userCount int
+		postCount int
+		err       error
+	)
 
-	userCount, err := p.state.DB.CountInstanceUsers(ctx, host)
-	if err != nil {
-		return nil, gtserror.NewErrorInternalError(err)
-	}
+	if config.GetInstanceStatsRandomize() {
+		// Use randomized stats.
+		stats := p.converter.RandomStats()
+		userCount = int(stats.TotalUsers)
+		postCount = int(stats.Statuses)
+	} else {
+		// Count actual stats.
+		host := config.GetHost()
 
-	postCount, err := p.state.DB.CountInstanceStatuses(ctx, host)
-	if err != nil {
-		return nil, gtserror.NewErrorInternalError(err)
+		userCount, err = p.state.DB.CountInstanceUsers(ctx, host)
+		if err != nil {
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+
+		postCount, err = p.state.DB.CountInstanceStatuses(ctx, host)
+		if err != nil {
+			return nil, gtserror.NewErrorInternalError(err)
+		}
 	}
 
 	return &apimodel.Nodeinfo{
diff --git a/internal/typeutils/converter.go b/internal/typeutils/converter.go
index 311839dc0..4fbe1dfd3 100644
--- a/internal/typeutils/converter.go
+++ b/internal/typeutils/converter.go
@@ -18,10 +18,17 @@
 package typeutils
 
 import (
+	crand "crypto/rand"
+	"math/big"
+	"math/rand"
 	"sync"
+	"sync/atomic"
+	"time"
 
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/filter/interaction"
 	"github.com/superseriousbusiness/gotosocial/internal/filter/visibility"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
 )
 
@@ -31,6 +38,7 @@ type Converter struct {
 	randAvatars    sync.Map
 	visFilter      *visibility.Filter
 	intFilter      *interaction.Filter
+	randStats      atomic.Pointer[apimodel.RandomStats]
 }
 
 func NewConverter(state *state.State) *Converter {
@@ -41,3 +49,53 @@ func NewConverter(state *state.State) *Converter {
 		intFilter:      interaction.NewFilter(state),
 	}
 }
+
+// RandomStats returns or generates
+// and returns random instance stats.
+func (c *Converter) RandomStats() apimodel.RandomStats {
+	now := time.Now()
+	stats := c.randStats.Load()
+	if stats != nil && time.Since(stats.Generated) < time.Hour {
+		// Random stats are still
+		// fresh (less than 1hr old),
+		// so return them as-is.
+		return *stats
+	}
+
+	// Generate new random stats.
+	newStats := genRandStats()
+	newStats.Generated = now
+	c.randStats.Store(&newStats)
+	return newStats
+}
+
+func genRandStats() apimodel.RandomStats {
+	const (
+		statusesMax = 10000000
+		usersMax    = 1000000
+	)
+
+	statusesB, err := crand.Int(crand.Reader, big.NewInt(statusesMax))
+	if err != nil {
+		// Only errs if something is buggered with the OS.
+		log.Panicf(nil, "error randomly generating statuses count: %v", err)
+	}
+
+	totalUsersB, err := crand.Int(crand.Reader, big.NewInt(usersMax))
+	if err != nil {
+		// Only errs if something is buggered with the OS.
+		log.Panicf(nil, "error randomly generating users count: %v", err)
+	}
+
+	// Monthly users should only ever
+	// be <= 100% of total users.
+	totalUsers := totalUsersB.Int64()
+	activeRatio := rand.Float64() //nolint
+	mau := int64(float64(totalUsers) * activeRatio)
+
+	return apimodel.RandomStats{
+		Statuses:           statusesB.Int64(),
+		TotalUsers:         totalUsers,
+		MonthlyActiveUsers: mau,
+	}
+}
diff --git a/internal/typeutils/internaltofrontend.go b/internal/typeutils/internaltofrontend.go
index 71ff71f8b..487e8434e 100644
--- a/internal/typeutils/internaltofrontend.go
+++ b/internal/typeutils/internaltofrontend.go
@@ -1745,6 +1745,12 @@ func (c *Converter) InstanceToAPIV1Instance(ctx context.Context, i *gtsmodel.Ins
 	stats["domain_count"] = util.Ptr(domainCount)
 	instance.Stats = stats
 
+	if config.GetInstanceStatsRandomize() {
+		// Whack some random stats on the instance
+		// to be injected by API handlers.
+		instance.RandomStats = c.RandomStats()
+	}
+
 	// thumbnail
 	iAccount, err := c.state.DB.GetInstanceAccount(ctx, "")
 	if err != nil {
@@ -1821,6 +1827,12 @@ func (c *Converter) InstanceToAPIV2Instance(ctx context.Context, i *gtsmodel.Ins
 		instance.Debug = util.Ptr(true)
 	}
 
+	if config.GetInstanceStatsRandomize() {
+		// Whack some random stats on the instance
+		// to be injected by API handlers.
+		instance.RandomStats = c.RandomStats()
+	}
+
 	// thumbnail
 	thumbnail := apimodel.InstanceV2Thumbnail{}
 
diff --git a/test/envparsing.sh b/test/envparsing.sh
index f9f3f25bc..565ecb1af 100755
--- a/test/envparsing.sh
+++ b/test/envparsing.sh
@@ -118,6 +118,7 @@ EXPECT=$(cat << "EOF"
         "nl",
         "en-GB"
     ],
+    "instance-stats-randomize": true,
     "instance-subscriptions-process-every": 86400000000000,
     "instance-subscriptions-process-from": "23:00",
     "landing-page-user": "admin",
@@ -248,6 +249,7 @@ GTS_INSTANCE_FEDERATION_SPAM_FILTER=true \
 GTS_INSTANCE_DELIVER_TO_SHARED_INBOXES=false \
 GTS_INSTANCE_INJECT_MASTODON_VERSION=true \
 GTS_INSTANCE_LANGUAGES="nl,en-gb" \
+GTS_INSTANCE_STATS_RANDOMIZE=true \
 GTS_ACCOUNTS_ALLOW_CUSTOM_CSS=true \
 GTS_ACCOUNTS_CUSTOM_CSS_LENGTH=5000 \
 GTS_ACCOUNTS_REGISTRATION_OPEN=true \