when LimitZero don't do any database queries.

README.md

@@ -69,6 +69,11 @@ func main() {
 
 	// there are many other configurable things you can set
 	relay.RejectEvent = append(relay.RejectEvent,
+		// built-in policies
+		policies.ValidateKind,
+
+		// define your own policies
+		policies.PreventLargeTags(80),
 		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"
@@ -79,6 +84,10 @@ func main() {
 
 	// you can request auth by rejecting an event or a request with the prefix "auth-required: "
 	relay.RejectFilter = append(relay.RejectFilter,
+		// built-in policies
+		policies.NoComplexFilters,
+
+		// define your own policies
 		func(ctx context.Context, filter nostr.Filter) (reject bool, msg string) {
 			if pubkey := khatru.GetAuthed(ctx); pubkey != "" {
 				log.Printf("request from %s\n", pubkey)

examples/readme-demo/main.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 
 	"github.com/fiatjaf/khatru"
+	"github.com/fiatjaf/khatru/policies"
 	"github.com/nbd-wtf/go-nostr"
 )
 
@@ -53,6 +54,11 @@ func main() {
 
 	// there are many other configurable things you can set
 	relay.RejectEvent = append(relay.RejectEvent,
+		// built-in policies
+		policies.ValidateKind,
+
+		// define your own policies
+		policies.PreventLargeTags(80),
 		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"
@@ -63,6 +69,10 @@ func main() {
 
 	// you can request auth by rejecting an event or a request with the prefix "auth-required: "
 	relay.RejectFilter = append(relay.RejectFilter,
+		// built-in policies
+		policies.NoComplexFilters,
+
+		// define your own policies
 		func(ctx context.Context, filter nostr.Filter) (reject bool, msg string) {
 			if pubkey := khatru.GetAuthed(ctx); pubkey != "" {
 				log.Printf("request from %s\n", pubkey)

go.mod

@@ -5,7 +5,7 @@ go 1.21.4
 require (
 	github.com/fasthttp/websocket v1.5.7
 	github.com/fiatjaf/eventstore v0.3.8
-	github.com/nbd-wtf/go-nostr v0.28.1
+	github.com/nbd-wtf/go-nostr v0.30.0
 	github.com/puzpuzpuz/xsync/v3 v3.0.2
 	github.com/rs/cors v1.7.0
 	github.com/sebest/xff v0.0.0-20210106013422-671bd2870b3a

go.sum

@@ -115,6 +115,8 @@ github.com/mattn/go-sqlite3 v1.14.18 h1:JL0eqdCOq6DJVNPSvArO/bIV9/P7fbGrV00LZHc+
 github.com/mattn/go-sqlite3 v1.14.18/go.mod h1:2eHXhiwb8IkHr+BDWZGa96P6+rkvnG63S2DGjv9HUNg=
 github.com/nbd-wtf/go-nostr v0.28.1 h1:XQi/lBsigBXHRm7IDBJE7SR9citCh9srgf8sA5iVW3A=
 github.com/nbd-wtf/go-nostr v0.28.1/go.mod h1:OQ8sNLFJnsj17BdqZiLSmjJBIFTfDqckEYC3utS4qoY=
+github.com/nbd-wtf/go-nostr v0.30.0 h1:rN085pe4IxmSBVht8LChZbWLggonjA8hPIk8l4/+Hjk=
+github.com/nbd-wtf/go-nostr v0.30.0/go.mod h1:tiKJY6fWYSujbTQb201Y+IQ3l4szqYVt+fsTnsm7FCk=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=

policies/filters.go

@@ -2,7 +2,6 @@ package policies
 
 import (
 	"context"
-
 	"slices"
 
 	"github.com/nbd-wtf/go-nostr"
@@ -48,7 +47,7 @@ func NoSearchQueries(ctx context.Context, filter nostr.Filter) (reject bool, msg
 func RemoveSearchQueries(ctx context.Context, filter *nostr.Filter) {
 	if filter.Search != "" {
 		filter.Search = ""
-		filter.Limit = -1 // signals that this query should be just skipped
+		filter.LimitZero = true // signals that this query should be just skipped
 	}
 }
 
@@ -63,7 +62,7 @@ func RemoveAllButKinds(kinds ...uint16) func(context.Context, *nostr.Filter) {
 			}
 			filter.Kinds = newKinds
 			if len(filter.Kinds) == 0 {
-				filter.Limit = -1 // signals that this query should be just skipped
+				filter.LimitZero = true // signals that this query should be just skipped
 			}
 		}
 	}
@@ -78,7 +77,7 @@ func RemoveAllButTags(tagNames ...string) func(context.Context, *nostr.Filter) {
 				}
 			}
 			if len(filter.Tags) == 0 {
-				filter.Limit = -1 // signals that this query should be just skipped
+				filter.LimitZero = true // signals that this query should be just skipped
 			}
 		}
 	}

policies/kind_validation.go

@@ -0,0 +1,29 @@
+package policies
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func ValidateKind(ctx context.Context, evt *nostr.Event) (bool, string) {
+	switch evt.Kind {
+	case 0:
+		var m struct {
+			Name string `json:"name"`
+		}
+		json.Unmarshal([]byte(evt.Content), &m)
+		if m.Name == "" {
+			return true, "missing json name in kind 0"
+		}
+	case 1:
+		return false, ""
+	case 2:
+		return true, "this kind has been deprecated"
+	}
+
+	// TODO: all other kinds
+
+	return false, ""
+}

responding.go

@@ -17,9 +17,8 @@ func (rl *Relay) handleRequest(ctx context.Context, id string, eose *sync.WaitGr
 		ovw(ctx, &filter)
 	}
 
-	if filter.Limit < 0 {
-		// this is a special situation through which the implementor signals to us that it doesn't want
-		// to event perform any queries whatsoever
+	if filter.LimitZero {
+		// don't do any queries, just subscribe to future events
 		return nil
 	}
 
@@ -29,7 +28,6 @@ func (rl *Relay) handleRequest(ctx context.Context, id string, eose *sync.WaitGr
 	// filter we can just reject it)
 	for _, reject := range rl.RejectFilter {
 		if reject, msg := reject(ctx, filter); reject {
-			ws.WriteJSON(nostr.NoticeEnvelope(msg))
 			return errors.New(nostr.NormalizeOKMessage(msg, "blocked"))
 		}
 	}