up3

server/session/handler_block_actor_data.go

@@ -0,0 +1,111 @@
+package session
+
+import (
+	"fmt"
+	"github.com/df-mc/dragonfly/server/block"
+	"github.com/df-mc/dragonfly/server/block/cube"
+	"github.com/df-mc/dragonfly/server/entity"
+	"github.com/df-mc/dragonfly/server/world"
+	"github.com/go-gl/mathgl/mgl64"
+	"github.com/sandertv/gophertunnel/minecraft/protocol/packet"
+	"strings"
+	"unicode/utf8"
+)
+
+// BlockActorDataHandler handles an incoming BlockActorData packet from the client, sent for some block entities like
+// signs when they are edited.
+type BlockActorDataHandler struct{}
+
+// Handle ...
+func (b BlockActorDataHandler) Handle(p packet.Packet, s *Session, tx *world.Tx, c Controllable) error {
+	pk := p.(*packet.BlockActorData)
+	if id, ok := pk.NBTData["id"]; ok {
+		pos := blockPosFromProtocol(pk.Position)
+		if !canReach(c, pos.Vec3Middle()) {
+			return fmt.Errorf("block at %v is not within reach", pos)
+		}
+		if id == "Sign" {
+			return b.handleSign(pk, pos, s, tx, c)
+		}
+		return fmt.Errorf("unhandled block actor data ID %v", id)
+	}
+	return fmt.Errorf("block actor data without 'id' tag: %v", pk.NBTData)
+}
+
+// handleSign handles the BlockActorData packet sent when editing a sign.
+func (b BlockActorDataHandler) handleSign(pk *packet.BlockActorData, pos cube.Pos, s *Session, tx *world.Tx, co Controllable) error {
+	if _, ok := tx.Block(pos).(block.Sign); !ok {
+		s.conf.Log.Debug("no sign at position of sign block actor data", "pos", pos.String())
+		return nil
+	}
+
+	frontText, err := b.textFromNBTData(pk.NBTData, true)
+	if err != nil {
+		return err
+	}
+	backText, err := b.textFromNBTData(pk.NBTData, false)
+	if err != nil {
+		return err
+	}
+	if err := co.EditSign(pos, frontText, backText); err != nil {
+		return err
+	}
+	return nil
+}
+
+// textFromNBTData attempts to retrieve the text from the NBT data of specific sign from the BlockActorData packet.
+func (b BlockActorDataHandler) textFromNBTData(data map[string]any, frontSide bool) (string, error) {
+	var sideData map[string]any
+	var side string
+	if frontSide {
+		frontSide, ok := data["FrontText"].(map[string]any)
+		if !ok {
+			return "", fmt.Errorf("sign block actor data 'FrontText' tag was not found or was not a map: %#v", data["FrontText"])
+		}
+		sideData = frontSide
+		side = "front"
+	} else {
+		backSide, ok := data["BackText"].(map[string]any)
+		if !ok {
+			return "", fmt.Errorf("sign block actor data 'BackText' tag was not found or was not a map: %#v", data["BackText"])
+		}
+		sideData = backSide
+		side = "back"
+	}
+	var text string
+	pkText, ok := sideData["Text"]
+	if !ok {
+		return "", fmt.Errorf("sign block actor data had no 'Text' tag for side %s", side)
+	}
+	if text, ok = pkText.(string); !ok {
+		return "", fmt.Errorf("sign block actor data 'Text' tag was not a string for side %s: %#v", side, pkText)
+	}
+
+	// Verify that the text was valid. It must be valid UTF8 and not more than 100 characters long.
+	text = strings.TrimRight(text, "\n")
+	if len(text) > 256 {
+		return "", fmt.Errorf("sign block actor data text was longer than 256 characters for side %s", side)
+	}
+	if !utf8.ValidString(text) {
+		return "", fmt.Errorf("sign block actor data text was not valid UTF8 for side %s", side)
+	}
+	return text, nil
+}
+
+// canReach checks if a player can reach a position with its current range. The range depends on if the player
+// is either survival or creative mode.
+func canReach(c Controllable, pos mgl64.Vec3) bool {
+	const (
+		creativeRange = 14.0
+		survivalRange = 8.0
+	)
+	if !c.GameMode().AllowsInteraction() {
+		return false
+	}
+
+	eyes := entity.EyePosition(c)
+	if c.GameMode().CreativeInventory() {
+		return eyes.Sub(pos).Len() <= creativeRange && !c.Dead()
+	}
+	return eyes.Sub(pos).Len() <= survivalRange && !c.Dead()
+}