fix RejectFilters application, support overwriting filters and add some filter plugin helpers.

handlers.go

@@ -168,12 +168,12 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 
 						filter := filters[i]
 
-						for _, reject := range rl.RejectFilter {
-							if rejecting, msg := reject(ctx, filter); rejecting {
-								ws.WriteJSON(nostr.NoticeEnvelope(msg))
-								continue
-							}
+						// overwrite the filter (for example, to eliminate some kinds or tags that we know we don't support)
+						for _, ovw := range rl.OverwriteCountFilter {
+							ovw(ctx, &filter)
 						}
+
+						// then check if we'll reject this filter
 						for _, reject := range rl.RejectCountFilter {
 							if rejecting, msg := reject(ctx, filter); rejecting {
 								ws.WriteJSON(nostr.NoticeEnvelope(msg))
@@ -181,6 +181,7 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 							}
 						}
 
+						// run the functions to count (generally it will be just one)
 						for _, count := range rl.CountEvents {
 							res, err := count(ctx, filter)
 							if err != nil {
@@ -215,14 +216,25 @@ func (rl *Relay) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 
 						filter := filters[i]
 
-						for _, reject := range rl.RejectCountFilter {
+						// overwrite the filter (for example, to eliminate some kinds or
+						// that we know we don't support)
+						for _, ovw := range rl.OverwriteFilter {
+							ovw(ctx, &filter)
+						}
+
+						// then check if we'll reject this filter (we apply this after overwriting
+						// because we may, for example, remove some things from the incoming filters
+						// that we know we don't support, and then if the end result is an empty
+						// filter we can just reject it)
+						for _, reject := range rl.RejectFilter {
 							if rejecting, msg := reject(ctx, filter); rejecting {
 								ws.WriteJSON(nostr.NoticeEnvelope(msg))
-								eose.Done()
 								continue
 							}
 						}
 
+						// run the functions to query events (generally just one,
+						// but we might be fetching stuff from multiple places)
 						eose.Add(len(rl.QueryEvents))
 						for _, query := range rl.QueryEvents {
 							ch, err := query(ctx, filter)

plugins/filters.go

@@ -2,26 +2,11 @@ package plugins
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/nbd-wtf/go-nostr"
+	"golang.org/x/exp/slices"
 )
 
-func NoPrefixFilters(ctx context.Context, filter nostr.Filter) (reject bool, msg string) {
-	for _, id := range filter.IDs {
-		if len(id) != 64 {
-			return true, fmt.Sprintf("filters can only contain full ids")
-		}
-	}
-	for _, pk := range filter.Authors {
-		if len(pk) != 64 {
-			return true, fmt.Sprintf("filters can only contain full pubkeys")
-		}
-	}
-
-	return false, ""
-}
-
 func NoComplexFilters(ctx context.Context, filter nostr.Filter) (reject bool, msg string) {
 	items := len(filter.Tags) + len(filter.Kinds)
 
@@ -31,3 +16,49 @@ func NoComplexFilters(ctx context.Context, filter nostr.Filter) (reject bool, ms
 
 	return false, ""
 }
+
+func NoEmptyFilters(ctx context.Context, filter nostr.Filter) (reject bool, msg string) {
+	c := len(filter.Kinds) + len(filter.IDs) + len(filter.Authors)
+	for _, tagItems := range filter.Tags {
+		c += len(tagItems)
+	}
+	if c == 0 {
+		return true, "can't handle empty filters"
+	}
+	return false, ""
+}
+
+func NoSearchQueries(ctx context.Context, filter nostr.Filter) (reject bool, msg string) {
+	if filter.Search != "" {
+		return true, "search is not supported"
+	}
+	return false, ""
+}
+
+func RemoveSearchQueries(ctx context.Context, filter *nostr.Filter) {
+	filter.Search = ""
+}
+
+func RemoveKinds(kinds ...int) func(context.Context, *nostr.Filter) {
+	return func(ctx context.Context, filter *nostr.Filter) {
+		if n := len(filter.Kinds); n > 0 {
+			newKinds := make([]int, 0, n)
+			for i := 0; i < n; i++ {
+				if k := filter.Kinds[i]; !slices.Contains(kinds, k) {
+					newKinds = append(newKinds, k)
+				}
+			}
+			filter.Kinds = newKinds
+		}
+	}
+}
+
+func RemoveTags(tagNames ...string) func(context.Context, *nostr.Filter) {
+	return func(ctx context.Context, filter *nostr.Filter) {
+		for tagName := range filter.Tags {
+			if slices.Contains(tagNames, tagName) {
+				delete(filter.Tags, tagName)
+			}
+		}
+	}
+}

relay.go

@@ -46,6 +46,8 @@ type Relay struct {
 	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)
+	OverwriteFilter          []func(ctx context.Context, filter *nostr.Filter)
+	OverwriteCountFilter     []func(ctx context.Context, filter *nostr.Filter)
 	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)