Add server infrastructure with login, status, and kick handlers

server/login_server.go

@@ -0,0 +1,179 @@
+package server
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log/slog"
+	"slices"
+
+	"github.com/admin-else/strom/api"
+	"github.com/admin-else/strom/event"
+	"github.com/admin-else/strom/proto"
+	"github.com/admin-else/strom/proto_base"
+	"github.com/admin-else/strom/proto_generated/v1_21_8"
+	"github.com/google/uuid"
+)
+
+var StatusServedError = errors.New("status served")
+
+var UnexpectedStatusRequest = UnexpectedNextStateError{proto_base.Status}
+
+type NameAndUUID struct {
+	Name string
+	UUID uuid.UUID
+}
+
+type UnexpectedNextStateError struct {
+	NextState proto_base.State
+}
+
+func (u UnexpectedNextStateError) Error() string {
+	return fmt.Sprintf("unexpected next state: %v", u.NextState)
+}
+
+type LoginServer struct {
+	*proto.Conn
+	//OnlineMode           bool FIXME: implement this
+	ServerHost           string
+	ServerPort           uint16
+	Requested            NameAndUUID
+	Given                *NameAndUUID
+	CompressionThreshold int32 //FIXME: implement this
+	Status               []byte
+	CompatibleVersions   []int32
+}
+
+func (l *LoginServer) OnHandshake(packet *v1_21_8.HandshakingToServerPacketSetProtocol) (err error) {
+	l.SetState(proto_base.State(packet.NextState))
+	l.ServerHost = packet.ServerHost
+	l.ServerPort = packet.ServerPort
+
+	if packet.NextState == int32(proto_base.Status) && l.Status != nil {
+		return
+	}
+
+	if packet.NextState != int32(proto_base.Login) {
+		err = UnexpectedNextStateError{proto_base.State(packet.NextState)}
+		return
+	}
+
+	if len(l.CompatibleVersions) != 0 && !slices.Contains(l.CompatibleVersions, packet.ProtocolVersion) {
+		err = fmt.Errorf("incompatible protocol version please use one of %v you can look up the real coresponding version at https://minecraft.wiki/w/Minecraft_Wiki:Projects/wiki.vg_merge/Protocol_version_numbers", l.CompatibleVersions)
+		return
+	}
+
+	return
+}
+
+func (l *LoginServer) OnStatusRequest(_ *v1_21_8.StatusToServerPacketPingStart) (err error) {
+	err = l.Send(&v1_21_8.StatusToClientPacketServerInfo{Response: string(l.Status)})
+	return
+}
+
+func (l *LoginServer) OnStatusPing(packet *v1_21_8.StatusToServerPacketPing) (err error) {
+	err = l.Send(&v1_21_8.StatusToClientPacketPing{Time: packet.Time})
+	if err != nil {
+		return
+	}
+	return event.HandlerDoneErr{Return: StatusServedError}
+}
+
+func (l *LoginServer) SetCompressionThreshold(threshold int32) (err error) {
+	err = l.Send(&v1_21_8.LoginToClientPacketCompress{Threshold: threshold})
+	if err != nil {
+		return
+	}
+	l.CompressionThreshold = threshold
+	return
+}
+
+func (l *LoginServer) OnLoginStart(packet *v1_21_8.LoginToServerPacketLoginStart) (err error) {
+	l.Requested = NameAndUUID{packet.Username, packet.PlayerUUID}
+	//err = l.SetCompressionThreshold(l.CompressionThreshold)
+	//if err != nil {
+	//	return
+	//}
+	if l.Given == nil {
+		l.Given = &l.Requested
+	}
+	err = l.Send(&v1_21_8.LoginToClientPacketSuccess{
+		Uuid:       l.Given.UUID,
+		Username:   l.Given.Name,
+		Properties: nil,
+	})
+	return
+}
+
+func (l *LoginServer) OnLoginAcknowledged(_ *v1_21_8.LoginToServerPacketLoginAcknowledged) (err error) {
+	l.SetState(proto_base.Configuration)
+	err = event.HandlerDoneErr{}
+	return
+}
+
+func (l *LoginServer) OnDefault(event event.Unhandled) (err error) {
+	err = fmt.Errorf("unexpected event during login: %#v", event)
+	return
+}
+
+func (l *LoginServer) OnStart(_ event.OnStart) (err error) {
+	return
+}
+
+func (l *LoginServer) OnCycle(_ event.Tick) (err error) {
+	return
+}
+
+type LoginServerSetting func(*LoginServer)
+
+func WithOtherAccount(a *api.Account) LoginServerSetting {
+	return func(s *LoginServer) {
+		if s.Given == nil {
+			return
+		}
+		s.Given = &NameAndUUID{
+			Name: a.Name,
+			UUID: a.Uuid,
+		}
+	}
+}
+
+func WithRawStatus(status []byte) LoginServerSetting {
+	return func(s *LoginServer) {
+		s.Status = status
+	}
+}
+
+func WithStatus(response StatusResponse) LoginServerSetting {
+	var status []byte
+	status, err := json.Marshal(response)
+	if err != nil {
+		panic(err)
+	}
+	slog.Debug("With status", "status", status)
+	return WithRawStatus(status)
+}
+
+func WithCompatibleVersionsRange(start, end int32) LoginServerSetting {
+	var versions []int32
+	for i := start; i <= end; i++ {
+		versions = append(versions, i)
+	}
+	return WithCompatibleVersions(versions...)
+}
+
+func WithCompatibleVersions(versions ...int32) LoginServerSetting {
+	return func(s *LoginServer) {
+		s.CompatibleVersions = append(versions)
+	}
+}
+
+func ServeLogin(c *proto.Conn, settings ...LoginServerSetting) (ret *LoginServer, err error) {
+	ret = &LoginServer{Conn: c}
+	for _, s := range settings {
+		s(ret)
+	}
+	ret.CompressionThreshold = 256
+	err = ret.Start(ret)
+	return
+}