fix replaceable handlers to not delete things all the time.

README.md

@@ -1 +1,116 @@
-khatru
+# khatru, a relay framework [![docs badge](https://img.shields.io/badge/docs-reference-blue)](https://pkg.go.dev/github.com/fiatjaf/khatru#Relay)
+
+Khatru makes it easy to write very very custom relays:
+
+  - custom event or filter acceptance policies
+  - custom `AUTH` handlers
+  - custom storage and pluggable databases
+  - custom webpages and other HTTP handlers
+
+Here's a sample:
+
+```go
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/fiatjaf/khatru"
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func main() {
+	// create the relay instance
+	relay := khatru.NewRelay()
+
+	// set up some basic properties (will be returned on the NIP-11 endpoint)
+	relay.Name = "my relay"
+	relay.PubKey = "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798"
+	relay.Description = "this is my custom relay"
+	relay.IconURL = "https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fliquipedia.net%2Fcommons%2Fimages%2F3%2F35%2FSCProbe.jpg&f=1&nofb=1&ipt=0cbbfef25bce41da63d910e86c3c343e6c3b9d63194ca9755351bb7c2efa3359&ipo=images"
+
+	// you must bring your own storage scheme -- if you want to have any
+	store := make(map[string]*nostr.Event, 120)
+
+	// set up the basic relay functions
+	relay.StoreEvent = append(relay.StoreEvent,
+		func(ctx context.Context, event *nostr.Event) error {
+			store[event.ID] = event
+			return nil
+		},
+	)
+	relay.QueryEvents = append(relay.QueryEvents,
+		func(ctx context.Context, filter nostr.Filter) (chan *nostr.Event, error) {
+			ch := make(chan *nostr.Event)
+			go func() {
+				for _, evt := range store {
+					if filter.Matches(evt) {
+						ch <- evt
+					}
+				}
+				close(ch)
+			}()
+			return ch, nil
+		},
+	)
+	relay.DeleteEvent = append(relay.DeleteEvent,
+		func(ctx context.Context, event *nostr.Event) error {
+			delete(store, event.ID)
+			return nil
+		},
+	)
+
+	// there are many other configurable things you can set
+	relay.RejectEvent = append(relay.RejectEvent,
+		func(ctx context.Context, event *nostr.Event) (reject bool, msg string) {
+			if event.PubKey == "fa984bd7dbb282f07e16e7ae87b26a2a7b9b90b7246a44771f0cf5ae58018f52" {
+				return true, "we don't allow this person to write here"
+			}
+			return false, "" // anyone else can
+		},
+	)
+	relay.OnConnect = append(relay.OnConnect,
+		func(ctx context.Context) {
+			// request NIP-42 AUTH from everybody
+			relay.RequestAuth(ctx)
+		},
+	)
+	relay.OnAuth = append(relay.OnAuth,
+		func(ctx context.Context, pubkey string) {
+			// and when they auth we just log that for nothing
+			log.Println(pubkey + " is authed!")
+		},
+	)
+	// check the docs for more goodies!
+
+	mux := relay.Router()
+	// set up other http handlers
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("content-type", "text/html")
+		fmt.Fprintf(w, `<b>welcome</b> to my relay!`)
+	})
+
+	// start the server
+	fmt.Println("running on :3334")
+	http.ListenAndServe(":3334", relay)
+}
+```
+
+### But I don't want to write my own database!
+
+Fear no more. Using the https://github.com/fiatjaf/eventstore module you get a bunch of compatible databases out of the box and you can just plug them into your relay. For example, [sqlite](https://pkg.go.dev/github.com/fiatjaf/eventstore/sqlite3):
+
+```go
+	db := sqlite3.SQLite3Backend{DatabaseURL: "/tmp/khatru-sqlite-tmp"}
+	if err := db.Init(); err != nil {
+		panic(err)
+	}
+
+	relay.StoreEvent = append(relay.StoreEvent, db.SaveEvent)
+	relay.QueryEvents = append(relay.QueryEvents, db.QueryEvents)
+	relay.CountEvents = append(relay.CountEvents, db.CountEvents)
+	relay.DeleteEvent = append(relay.DeleteEvent, db.DeleteEvent)
+```

add-event.go

@@ -38,8 +38,7 @@ func (rl *Relay) AddEvent(ctx context.Context, evt *nostr.Event) error {
 				if err != nil {
 					continue
 				}
-				previous := <-ch
-				if previous != nil {
+				if previous := <-ch; previous != nil && isOlder(previous, evt) {
 					for _, del := range rl.DeleteEvent {
 						del(ctx, previous)
 					}
@@ -54,8 +53,7 @@ func (rl *Relay) AddEvent(ctx context.Context, evt *nostr.Event) error {
 					if err != nil {
 						continue
 					}
-					previous := <-ch
-					if previous != nil {
+					if previous := <-ch; previous != nil && isOlder(previous, evt) {
 						for _, del := range rl.DeleteEvent {
 							del(ctx, previous)
 						}
@@ -86,7 +84,11 @@ func (rl *Relay) AddEvent(ctx context.Context, evt *nostr.Event) error {
 		}
 	}
 
+	for _, ovw := range rl.OverwriteResponseEvent {
+		ovw(ctx, evt)
+	}
 	notifyListeners(evt)
+
 	return nil
 }
 

examples/readme-demo/main.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/fiatjaf/khatru"
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func main() {
+	// create the relay instance
+	relay := khatru.NewRelay()
+
+	// set up some basic properties (will be returned on the NIP-11 endpoint)
+	relay.Name = "my relay"
+	relay.PubKey = "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798"
+	relay.Description = "this is my custom relay"
+	relay.IconURL = "https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fliquipedia.net%2Fcommons%2Fimages%2F3%2F35%2FSCProbe.jpg&f=1&nofb=1&ipt=0cbbfef25bce41da63d910e86c3c343e6c3b9d63194ca9755351bb7c2efa3359&ipo=images"
+
+	// you must bring your own storage scheme -- if you want to have any
+	store := make(map[string]*nostr.Event, 120)
+
+	// set up the basic relay functions
+	relay.StoreEvent = append(relay.StoreEvent,
+		func(ctx context.Context, event *nostr.Event) error {
+			store[event.ID] = event
+			return nil
+		},
+	)
+	relay.QueryEvents = append(relay.QueryEvents,
+		func(ctx context.Context, filter nostr.Filter) (chan *nostr.Event, error) {
+			ch := make(chan *nostr.Event)
+			go func() {
+				for _, evt := range store {
+					if filter.Matches(evt) {
+						ch <- evt
+					}
+				}
+				close(ch)
+			}()
+			return ch, nil
+		},
+	)
+	relay.DeleteEvent = append(relay.DeleteEvent,
+		func(ctx context.Context, event *nostr.Event) error {
+			delete(store, event.ID)
+			return nil
+		},
+	)
+
+	// there are many other configurable things you can set
+	relay.RejectEvent = append(relay.RejectEvent,
+		func(ctx context.Context, event *nostr.Event) (reject bool, msg string) {
+			if event.PubKey == "fa984bd7dbb282f07e16e7ae87b26a2a7b9b90b7246a44771f0cf5ae58018f52" {
+				return true, "we don't allow this person to write here"
+			}
+			return false, "" // anyone else can
+		},
+	)
+	relay.OnConnect = append(relay.OnConnect,
+		func(ctx context.Context) {
+			// request NIP-42 AUTH from everybody
+			relay.RequestAuth(ctx)
+		},
+	)
+	relay.OnAuth = append(relay.OnAuth,
+		func(ctx context.Context, pubkey string) {
+			// and when they auth we just log that for nothing
+			log.Println(pubkey + " is authed!")
+		},
+	)
+	// check the docs for more goodies!
+
+	mux := relay.Router()
+	// set up other http handlers
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("content-type", "text/html")
+		fmt.Fprintf(w, `<b>welcome</b> to my relay!`)
+	})
+
+	// start the server
+	fmt.Println("running on :3334")
+	http.ListenAndServe(":3334", relay)
+}

handlers.go

@@ -124,12 +124,10 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 
 					// check signature (requires the ID to be set)
 					if ok, err := evt.CheckSignature(); err != nil {
-						reason := "error: failed to verify signature"
-						ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: false, Reason: &reason})
+						ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: false, Reason: "error: failed to verify signature"})
 						return
 					} else if !ok {
-						reason := "invalid: signature is invalid"
-						ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: false, Reason: &reason})
+						ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: false, Reason: "invalid: signature is invalid"})
 						return
 					}
 
@@ -139,12 +137,12 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 					} else {
 						err = rl.AddEvent(ctx, &evt)
 					}
-					var reason *string
+
+					var reason string
 					if err == nil {
 						ok = true
 					} else {
-						msg := err.Error()
-						reason = &msg
+						reason = err.Error()
 					}
 					ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: ok, Reason: reason})
 				case "COUNT":
@@ -236,6 +234,9 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 
 							go func(ch chan *nostr.Event) {
 								for event := range ch {
+									for _, ovw := range rl.OverwriteResponseEvent {
+										ovw(ctx, event)
+									}
 									ws.WriteJSON(nostr.EventEnvelope{SubscriptionID: &id, Event: *event})
 								}
 								eose.Done()
@@ -273,8 +274,7 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 							ctx = context.WithValue(ctx, AUTH_CONTEXT_KEY, pubkey)
 							ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: true})
 						} else {
-							reason := "error: failed to authenticate"
-							ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: false, Reason: &reason})
+							ws.WriteJSON(nostr.OKEnvelope{EventID: evt.ID, OK: false, Reason: "error: failed to authenticate"})
 						}
 					}
 				}

plugins/events.go

@@ -56,3 +56,21 @@ func RestrictToSpecifiedKinds(kinds ...uint16) func(context.Context, *nostr.Even
 		return true, "event kind not allowed"
 	}
 }
+
+func PreventTimestampsInThePast(thresholdSeconds nostr.Timestamp) func(context.Context, *nostr.Event) (bool, string) {
+	return func(ctx context.Context, event *nostr.Event) (reject bool, msg string) {
+		if nostr.Now()-event.CreatedAt > thresholdSeconds {
+			return true, "event too old"
+		}
+		return false, ""
+	}
+}
+
+func PreventTimestampsInTheFuture(thresholdSeconds nostr.Timestamp) func(context.Context, *nostr.Event) (bool, string) {
+	return func(ctx context.Context, event *nostr.Event) (reject bool, msg string) {
+		if event.CreatedAt-nostr.Now() > thresholdSeconds {
+			return true, "event too much in the future"
+		}
+		return false, ""
+	}
+}

relay.go

@@ -45,6 +45,7 @@ type Relay struct {
 	RejectFilter             []func(ctx context.Context, filter nostr.Filter) (reject bool, msg string)
 	RejectCountFilter        []func(ctx context.Context, filter nostr.Filter) (reject bool, msg string)
 	OverwriteDeletionOutcome []func(ctx context.Context, target *nostr.Event, deletion *nostr.Event) (acceptDeletion bool, msg string)
+	OverwriteResponseEvent   []func(ctx context.Context, event *nostr.Event)
 	StoreEvent               []func(ctx context.Context, event *nostr.Event) error
 	DeleteEvent              []func(ctx context.Context, event *nostr.Event) error
 	QueryEvents              []func(ctx context.Context, filter nostr.Filter) (chan *nostr.Event, error)

utils.go

@@ -5,6 +5,8 @@ import (
 	"hash/maphash"
 	"regexp"
 	"unsafe"
+
+	"github.com/nbd-wtf/go-nostr"
 )
 
 const (
@@ -26,4 +28,11 @@ func GetAuthed(ctx context.Context) string {
 	return authedPubkey.(string)
 }
 
-func pointerHasher[V any](_ maphash.Seed, k *V) uint64 { return uint64(uintptr(unsafe.Pointer(k))) }
+func pointerHasher[V any](_ maphash.Seed, k *V) uint64 {
+	return uint64(uintptr(unsafe.Pointer(k)))
+}
+
+func isOlder(previous, next *nostr.Event) bool {
+	return previous.CreatedAt < next.CreatedAt ||
+		(previous.CreatedAt == next.CreatedAt && previous.ID > next.ID)
+}