sdk: test and fix encode/decode relay lists.

sdk/event_relays.go

@@ -21,6 +21,9 @@ func makeEventRelayKey(eventID []byte) []byte {
 func encodeRelayList(relays []string) []byte {
 	totalSize := 0
 	for _, relay := range relays {
+		if len(relay) > 256 {
+			continue
+		}
 		totalSize += 1 + len(relay) // 1 byte for length prefix
 	}
 
@@ -41,7 +44,7 @@ func encodeRelayList(relays []string) []byte {
 }
 
 func decodeRelayList(data []byte) []string {
-	relays := make([]string, 0)
+	relays := make([]string, 0, 6)
 	offset := 0
 
 	for offset < len(data) {

sdk/event_relays_test.go

@@ -0,0 +1,81 @@
+package sdk
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEncodeDecodeRelayList(t *testing.T) {
+	tests := []struct {
+		name   string
+		relays []string
+	}{
+		{
+			name:   "empty list",
+			relays: []string{},
+		},
+		{
+			name:   "single relay",
+			relays: []string{"wss://relay.example.com"},
+		},
+		{
+			name: "multiple relays",
+			relays: []string{
+				"wss://relay1.example.com",
+				"wss://relay23.example.com",
+				"wss://relay456.example.com",
+			},
+		},
+		{
+			name: "relays with varying lengths",
+			relays: []string{
+				"wss://a.com",
+				"wss://very-long-relay-url.example.com",
+				"wss://b.com",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// test encoding
+			encoded := encodeRelayList(tt.relays)
+			require.NotNil(t, encoded)
+
+			// test decoding
+			decoded := decodeRelayList(encoded)
+			require.Equal(t, tt.relays, decoded)
+		})
+	}
+
+	t.Run("malformed data", func(t *testing.T) {
+		// test with truncated data
+		decoded := decodeRelayList([]byte{5, 'h', 'e'}) // length prefix of 5 but only 2 bytes of data
+		require.Nil(t, decoded)
+
+		// test with invalid length prefix
+		decoded = decodeRelayList([]byte{255}) // length prefix but no data
+		require.Nil(t, decoded)
+	})
+
+	t.Run("skip too long relay URLs", func(t *testing.T) {
+		// create a long URL by repeating 'a' 257 times
+		longURL := "wss://" + strings.Repeat("a", 257) + ".com"
+		longRelays := []string{
+			"wss://normal.example.com",
+			longURL,
+			"wss://also-normal.example.com",
+		}
+
+		encoded := encodeRelayList(longRelays)
+		decoded := decodeRelayList(encoded)
+
+		// should only contain the normal URLs
+		require.Equal(t, []string{
+			"wss://normal.example.com",
+			"wss://also-normal.example.com",
+		}, decoded)
+	})
+}