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session.go
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session.go
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package session
import (
"context"
"errors"
"fmt"
"github.com/df-mc/atomic"
"github.com/df-mc/dragonfly/server/block"
"github.com/df-mc/dragonfly/server/block/cube"
"github.com/df-mc/dragonfly/server/internal/sliceutil"
"github.com/df-mc/dragonfly/server/item"
"github.com/df-mc/dragonfly/server/item/inventory"
"github.com/df-mc/dragonfly/server/item/recipe"
"github.com/df-mc/dragonfly/server/player/chat"
"github.com/df-mc/dragonfly/server/player/form"
"github.com/df-mc/dragonfly/server/world"
"github.com/go-gl/mathgl/mgl64"
"github.com/sandertv/gophertunnel/minecraft"
"github.com/sandertv/gophertunnel/minecraft/nbt"
"github.com/sandertv/gophertunnel/minecraft/protocol"
"github.com/sandertv/gophertunnel/minecraft/protocol/login"
"github.com/sandertv/gophertunnel/minecraft/protocol/packet"
"github.com/sandertv/gophertunnel/minecraft/text"
"io"
"net"
"sync"
"time"
)
// Session handles incoming packets from connections and sends outgoing packets by providing a thin layer
// of abstraction over direct packets. A Session basically 'controls' an entity.
type Session struct {
log Logger
once, connOnce sync.Once
c Controllable
conn Conn
handlers map[uint32]packetHandler
// onStop is called when the session is stopped. The controllable passed is the controllable that the
// session controls.
onStop func(controllable Controllable)
currentScoreboard atomic.Value[string]
currentLines atomic.Value[[]string]
chunkLoader *world.Loader
chunkRadius, maxChunkRadius int32
teleportPos atomic.Value[*mgl64.Vec3]
entityMutex sync.RWMutex
// currentEntityRuntimeID holds the runtime ID assigned to the last entity. It is incremented for every
// entity spawned to the session.
currentEntityRuntimeID uint64
// entityRuntimeIDs holds a list of all runtime IDs of entities spawned to the session.
entityRuntimeIDs map[world.Entity]uint64
entities map[uint64]world.Entity
hiddenEntities map[world.Entity]struct{}
// heldSlot is the slot in the inventory that the controllable is holding.
heldSlot *atomic.Uint32
inv, offHand, enderChest, ui *inventory.Inventory
armour *inventory.Armour
breakingPos cube.Pos
inTransaction, containerOpened atomic.Bool
openedWindowID atomic.Uint32
openedContainerID atomic.Uint32
openedWindow atomic.Value[*inventory.Inventory]
openedPos atomic.Value[cube.Pos]
swingingArm atomic.Bool
recipes map[uint32]recipe.Recipe
blobMu sync.Mutex
blobs map[uint64][]byte
openChunkTransactions []map[uint64]struct{}
invOpened bool
joinMessage, quitMessage string
closeBackground chan struct{}
}
// Conn represents a connection that packets are read from and written to by a Session. In addition, it holds some
// information on the identity of the Session.
type Conn interface {
io.Closer
// IdentityData returns the login.IdentityData of a Conn. It contains the UUID, XUID and username of the connection.
IdentityData() login.IdentityData
// ClientData returns the login.ClientData of a Conn. This includes less sensitive data of the player like its skin,
// language code and other non-essential information.
ClientData() login.ClientData
// ClientCacheEnabled specifies if the Conn has the client cache, used for caching chunks client-side, enabled or
// not. Some platforms, like the Nintendo Switch, have this disabled at all times.
ClientCacheEnabled() bool
// ChunkRadius returns the chunk radius as requested by the client at the other end of the Conn.
ChunkRadius() int
// Latency returns the current latency measured over the Conn.
Latency() time.Duration
// Flush flushes the packets buffered by the Conn, sending all of them out immediately.
Flush() error
// RemoteAddr returns the remote network address.
RemoteAddr() net.Addr
// ReadPacket reads a packet.Packet from the Conn. An error is returned if a deadline was set that was
// exceeded or if the Conn was closed while awaiting a packet.
ReadPacket() (pk packet.Packet, err error)
// WritePacket writes a packet.Packet to the Conn. An error is returned if the Conn was closed before sending the
// packet.
WritePacket(pk packet.Packet) error
// StartGameContext starts the game for the Conn with a context to cancel it.
StartGameContext(ctx context.Context, data minecraft.GameData) error
}
// Logger is used to write debug messages to. These messages are sent whenever handling of a packet of a client fails.
type Logger interface {
Errorf(format string, a ...any)
Debugf(format string, a ...any)
}
// Nop represents a no-operation session. It does not do anything when sending a packet to it.
var Nop = &Session{}
// session is a slice of all open sessions. It is protected by the sessionMu, which must be locked whenever
// accessing the value.
var sessions []*Session
var sessionMu sync.Mutex
// selfEntityRuntimeID is the entity runtime (or unique) ID of the controllable that the session holds.
const selfEntityRuntimeID = 1
// errSelfRuntimeID is an error returned during packet handling for fields that refer to the player itself and
// must therefore always be 1.
var errSelfRuntimeID = errors.New("invalid entity runtime ID: runtime ID for self must always be 1")
// New returns a new session using a controllable entity. The session will control this entity using the
// packets that it receives.
// New takes the connection from which to accept packets. It will start handling these packets after a call to
// Session.Spawn().
func New(conn Conn, maxChunkRadius int, log Logger, joinMessage, quitMessage string) *Session {
r := conn.ChunkRadius()
if r > maxChunkRadius {
r = maxChunkRadius
_ = conn.WritePacket(&packet.ChunkRadiusUpdated{ChunkRadius: int32(r)})
}
s := &Session{}
*s = Session{
openChunkTransactions: make([]map[uint64]struct{}, 0, 8),
closeBackground: make(chan struct{}),
ui: inventory.New(53, s.handleInterfaceUpdate),
handlers: map[uint32]packetHandler{},
entityRuntimeIDs: map[world.Entity]uint64{},
entities: map[uint64]world.Entity{},
hiddenEntities: map[world.Entity]struct{}{},
blobs: map[uint64][]byte{},
chunkRadius: int32(r),
maxChunkRadius: int32(maxChunkRadius),
conn: conn,
log: log,
currentEntityRuntimeID: 1,
heldSlot: atomic.NewUint32(0),
joinMessage: joinMessage,
quitMessage: quitMessage,
openedWindow: *atomic.NewValue(inventory.New(1, nil)),
}
s.registerHandlers()
return s
}
// Spawn makes the Controllable passed spawn in the world.World.
// The function passed will be called when the session stops running.
func (s *Session) Spawn(c Controllable, pos mgl64.Vec3, w *world.World, gm world.GameMode, onStop func(controllable Controllable)) {
s.onStop = onStop
s.c = c
s.recipes = make(map[uint32]recipe.Recipe)
s.entityRuntimeIDs[c] = selfEntityRuntimeID
s.entities[selfEntityRuntimeID] = c
s.chunkLoader = world.NewLoader(int(s.chunkRadius), w, s)
s.chunkLoader.Move(pos)
s.writePacket(&packet.NetworkChunkPublisherUpdate{
Position: protocol.BlockPos{int32(pos[0]), int32(pos[1]), int32(pos[2])},
Radius: uint32(s.chunkRadius) << 4,
})
s.sendAvailableEntities()
s.initPlayerList()
world_add(c, w)
s.c.SetGameMode(gm)
s.SendSpeed(0.1)
for _, e := range s.c.Effects() {
s.SendEffect(e)
}
chat.Global.Subscribe(c)
if s.joinMessage != "" {
_, _ = fmt.Fprintln(chat.Global, text.Colourf("<yellow>%v</yellow>", fmt.Sprintf(s.joinMessage, s.conn.IdentityData().DisplayName)))
}
s.sendInv(s.inv, protocol.WindowIDInventory)
s.sendInv(s.ui, protocol.WindowIDUI)
s.sendInv(s.offHand, protocol.WindowIDOffHand)
s.sendInv(s.armour.Inventory(), protocol.WindowIDArmour)
s.writePacket(&packet.CreativeContent{Items: creativeItems()})
s.sendRecipes()
}
// Start makes the session start handling incoming packets from the client.
func (s *Session) Start() {
s.c.World().AddEntity(s.c)
go s.handlePackets()
}
// Controllable returns the Controllable entity that the Session controls.
func (s *Session) Controllable() Controllable {
return s.c
}
// Close closes the session, which in turn closes the controllable and the connection that the session
// manages. Close ensures the method only runs code on the first call.
func (s *Session) Close() error {
s.once.Do(s.close)
return nil
}
// close closes the session, which in turn closes the controllable and the connection that the session
// manages.
func (s *Session) close() {
_ = s.c.Close()
// Move UI inventory items to the main inventory.
for _, it := range s.ui.Items() {
if _, err := s.inv.AddItem(it); err != nil {
// We couldn't add the item to the main inventory (probably because it was full), so we drop it instead.
s.c.Drop(it)
}
}
s.onStop(s.c)
// Clear the inventories so that they no longer hold references to the connection.
_ = s.inv.Close()
_ = s.offHand.Close()
_ = s.armour.Close()
s.closeCurrentContainer()
_ = s.chunkLoader.Close()
s.c.World().RemoveEntity(s.c)
// This should always be called last due to the timing of the removal of entity runtime IDs.
s.closePlayerList()
s.entityMutex.Lock()
s.entityRuntimeIDs, s.entities = map[world.Entity]uint64{}, map[uint64]world.Entity{}
s.entityMutex.Unlock()
if s.quitMessage != "" {
_, _ = fmt.Fprintln(chat.Global, text.Colourf("<yellow>%v</yellow>", fmt.Sprintf(s.quitMessage, s.conn.IdentityData().DisplayName)))
}
chat.Global.Unsubscribe(s.c)
}
// CloseConnection closes the underlying connection of the session so that the session ends up being closed
// eventually.
func (s *Session) CloseConnection() {
s.connOnce.Do(func() {
_ = s.conn.Close()
s.closeBackground <- struct{}{}
})
}
// Addr returns the net.Addr of the client.
func (s *Session) Addr() net.Addr {
return s.conn.RemoteAddr()
}
// Latency returns the latency of the connection.
func (s *Session) Latency() time.Duration {
return s.conn.Latency()
}
// ClientData returns the login.ClientData of the underlying *minecraft.Conn.
func (s *Session) ClientData() login.ClientData {
return s.conn.ClientData()
}
// handlePackets continuously handles incoming packets from the connection. It processes them accordingly.
// Once the connection is closed, handlePackets will return.
func (s *Session) handlePackets() {
go s.background()
defer func() {
// If this function ends up panicking, we don't want to call s.Close() as it may cause the entire
// server to freeze without printing the actual panic message.
// Instead, we check if there is a panic to recover, and just propagate the panic if this does happen
// to be the case.
if err := recover(); err != nil {
panic(err)
}
_ = s.Close()
}()
for {
pk, err := s.conn.ReadPacket()
if err != nil {
return
}
if err := s.handlePacket(pk); err != nil {
// An error occurred during the handling of a packet. Print the error and stop handling any more
// packets.
s.log.Debugf("failed processing packet from %v (%v): %v\n", s.conn.RemoteAddr(), s.c.Name(), err)
return
}
}
}
// background performs background tasks of the Session. This includes chunk sending and automatic command updating.
// background returns when the Session's connection is closed using CloseConnection.
func (s *Session) background() {
var (
t = time.NewTicker(time.Second / 20)
r = s.sendAvailableCommands()
enums, enumValues = s.enums()
ok bool
i int
)
defer t.Stop()
for {
select {
case <-t.C:
s.sendChunks()
if i++; i%20 == 0 {
// Enum resending happens relatively often and frequent updates are more important than with full
// command changes. Those are generally only related to permission changes, which doesn't happen often.
s.resendEnums(enums, enumValues)
}
if i%100 == 0 {
// Try to resend commands only every 5 seconds.
if r, ok = s.resendCommands(r); ok {
enums, enumValues = s.enums()
}
}
case <-s.closeBackground:
return
}
}
}
// sendChunks sends the next up to 4 chunks to the connection. What chunks are loaded depends on the connection of
// the chunk loader and the chunks that were previously loaded.
func (s *Session) sendChunks() {
const maxChunkTransactions = 8
if w := s.c.World(); s.chunkLoader.World() != w && w != nil {
s.handleWorldSwitch(w)
}
s.blobMu.Lock()
toLoad := maxChunkTransactions - len(s.openChunkTransactions)
s.blobMu.Unlock()
if toLoad > 4 {
toLoad = 4
}
s.chunkLoader.Load(toLoad)
}
// handleWorldSwitch handles the player of the Session switching worlds.
func (s *Session) handleWorldSwitch(w *world.World) {
if s.conn.ClientCacheEnabled() {
s.blobMu.Lock()
// Force out all blobs before changing worlds. This ensures no outdated chunk loading in the new world.
resp := &packet.ClientCacheMissResponse{Blobs: make([]protocol.CacheBlob, 0, len(s.blobs))}
for h, blob := range s.blobs {
resp.Blobs = append(resp.Blobs, protocol.CacheBlob{Hash: h, Payload: blob})
}
s.writePacket(resp)
s.blobs = map[uint64][]byte{}
s.openChunkTransactions = nil
s.blobMu.Unlock()
}
same, dim := w.Dimension() == s.chunkLoader.World().Dimension(), int32(w.Dimension().EncodeDimension())
if !same {
s.changeDimension(dim, false)
}
s.ViewEntityTeleport(s.c, s.c.Position())
s.chunkLoader.ChangeWorld(w)
}
// changeDimension changes the dimension of the client. If silent is set to true, the portal noise will be stopped
// immediately.
func (s *Session) changeDimension(dim int32, silent bool) {
s.writePacket(&packet.ChangeDimension{Dimension: dim, Position: vec64To32(s.c.Position().Add(entityOffset(s.c)))})
s.writePacket(&packet.StopSound{StopAll: silent})
s.writePacket(&packet.PlayStatus{Status: packet.PlayStatusPlayerSpawn})
}
// handlePacket handles an incoming packet, processing it accordingly. If the packet had invalid data or was
// otherwise not valid in its context, an error is returned.
func (s *Session) handlePacket(pk packet.Packet) error {
handler, ok := s.handlers[pk.ID()]
if !ok {
s.log.Debugf("unhandled packet %T%v from %v\n", pk, fmt.Sprintf("%+v", pk)[1:], s.conn.RemoteAddr())
return nil
}
if handler == nil {
// A nil handler means it was explicitly unhandled.
return nil
}
if err := handler.Handle(pk, s); err != nil {
return fmt.Errorf("%T: %w", pk, err)
}
return nil
}
// registerHandlers registers all packet handlers found in the packetHandler package.
func (s *Session) registerHandlers() {
s.handlers = map[uint32]packetHandler{
packet.IDActorEvent: nil,
packet.IDAdventureSettings: nil, // Deprecated, the client still sends this though.
packet.IDAnimate: nil,
packet.IDAnvilDamage: nil,
packet.IDBlockActorData: &BlockActorDataHandler{},
packet.IDBlockPickRequest: &BlockPickRequestHandler{},
packet.IDBookEdit: &BookEditHandler{},
packet.IDBossEvent: nil,
packet.IDClientCacheBlobStatus: &ClientCacheBlobStatusHandler{},
packet.IDCommandRequest: &CommandRequestHandler{},
packet.IDContainerClose: &ContainerCloseHandler{},
packet.IDCraftingEvent: nil,
packet.IDEmote: &EmoteHandler{},
packet.IDEmoteList: nil,
packet.IDFilterText: nil,
packet.IDInteract: &InteractHandler{},
packet.IDInventoryTransaction: &InventoryTransactionHandler{},
packet.IDItemFrameDropItem: nil,
packet.IDItemStackRequest: &ItemStackRequestHandler{changes: map[byte]map[byte]changeInfo{}, responseChanges: map[int32]map[*inventory.Inventory]map[byte]responseChange{}},
packet.IDLevelSoundEvent: &LevelSoundEventHandler{},
packet.IDMobEquipment: &MobEquipmentHandler{},
packet.IDModalFormResponse: &ModalFormResponseHandler{forms: make(map[uint32]form.Form)},
packet.IDMovePlayer: nil,
packet.IDPlayerAction: &PlayerActionHandler{},
packet.IDPlayerAuthInput: &PlayerAuthInputHandler{},
packet.IDPlayerSkin: &PlayerSkinHandler{},
packet.IDRequestAbility: &RequestAbilityHandler{},
packet.IDRequestChunkRadius: &RequestChunkRadiusHandler{},
packet.IDRespawn: &RespawnHandler{},
packet.IDSubChunkRequest: &SubChunkRequestHandler{},
packet.IDText: &TextHandler{},
packet.IDTickSync: nil,
}
}
// handleInterfaceUpdate handles an update to the UI inventory, used for updating enchantment options and possibly more
// in the future.
func (s *Session) handleInterfaceUpdate(slot int, _, item item.Stack) {
if slot == enchantingInputSlot && s.containerOpened.Load() {
pos := s.openedPos.Load()
b := s.c.World().Block(pos)
if _, enchanting := b.(block.EnchantingTable); enchanting {
s.sendEnchantmentOptions(s.c.World(), pos, item)
}
}
}
// writePacket writes a packet to the session's connection if it is not Nop.
func (s *Session) writePacket(pk packet.Packet) {
if s == Nop {
return
}
_ = s.conn.WritePacket(pk)
}
// initPlayerList initialises the player list of the session and sends the session itself to all other
// sessions currently open.
func (s *Session) initPlayerList() {
sessionMu.Lock()
sessions = append(sessions, s)
for _, session := range sessions {
// AddStack the player of the session to all sessions currently open, and add the players of all sessions
// currently open to the player list of the new session.
session.addToPlayerList(s)
if s != session {
s.addToPlayerList(session)
}
}
sessionMu.Unlock()
}
// closePlayerList closes the player list of the session and removes the session from the player list of all
// other sessions.
func (s *Session) closePlayerList() {
sessionMu.Lock()
for _, session := range sessions {
// Remove the player of the session from the player list of all other sessions.
session.removeFromPlayerList(s)
}
sessions = sliceutil.DeleteVal(sessions, s)
sessionMu.Unlock()
}
// actorIdentifier represents the structure of an actor identifier sent over the network.
type actorIdentifier struct {
// ID is a unique namespaced identifier for the entity.
ID string `nbt:"id"`
}
// sendAvailableEntities sends all registered entities to the player.
func (s *Session) sendAvailableEntities() {
var identifiers []actorIdentifier
for _, entity := range world.Entities() {
identifiers = append(identifiers, actorIdentifier{ID: entity.Type().EncodeEntity()})
}
serializedEntityData, err := nbt.Marshal(map[string]any{"idlist": identifiers})
if err != nil {
panic("should never happen")
}
s.writePacket(&packet.AvailableActorIdentifiers{SerialisedEntityIdentifiers: serializedEntityData})
}