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Fix login start packet decoding for 1.18.2 up to 1.20.2 (#421)

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Signed-off-by: Fred Heinecke <fred.heinecke@yahoo.com>
This commit is contained in:
solidDoWant
2025-06-29 07:37:26 -05:00
committed by GitHub
parent 749b090c73
commit 805cebd856
10 changed files with 217 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Dockerfile
+1 -1
View File
@@ -1,4 +1,4 @@
FROM golang:1.23 AS builder
FROM golang:1.24 AS builder
WORKDIR /build
mcproto/decode.go
+65 -4
View File
@@ -21,10 +21,11 @@ func DecodeHandshake(data interface{}) (*Handshake, error) {
buffer := bytes.NewBuffer(dataBytes)
var err error
handshake.ProtocolVersion, err = ReadVarInt(buffer)
protocolVersion, err := ReadVarInt(buffer)
if err != nil {
return nil, err
}
handshake.ProtocolVersion = ProtocolVersion(protocolVersion)
handshake.ServerAddress, err = ReadString(buffer)
if err != nil {
@@ -48,13 +49,13 @@ func DecodeHandshake(data interface{}) (*Handshake, error) {
}
// DecodeLoginStart takes the Packet.Data bytes and decodes a LoginStart message from it
func DecodeLoginStart(data interface{}) (*LoginStart, error) {
func DecodeLoginStart(protocolVersion ProtocolVersion, data interface{}) (*LoginStart, error) {
dataBytes, ok := data.([]byte)
if !ok {
return nil, errors.New(invalidPacketDataBytesMsg)
}
loginStart := &LoginStart{}
loginStart := NewLoginStart()
buffer := bytes.NewBuffer(dataBytes)
var err error
@@ -63,10 +64,70 @@ func DecodeLoginStart(data interface{}) (*LoginStart, error) {
return loginStart, errors.Wrap(err, "failed to read username")
}
loginStart.PlayerUuid, err = ReadUuid(buffer)
// These versions can send player keypair data. Ignore it.
// References:
// * https://github.com/MCCTeam/Minecraft-Console-Client/blob/f785f509f228bf787c237ac139e6f666a960819a/MinecraftClient/Protocol/Handlers/Protocol18.cs#L2808-L2828
// * https://minecraft.wiki/w/Minecraft_Wiki:Projects/wiki.vg_merge/Protocol?oldid=2772902#Login_Start
if protocolVersion >= ProtocolVersion1_19 && protocolVersion <= ProtocolVersion1_19_2 {
hasSignatureData, err := ReadBoolean(buffer)
if err != nil {
return loginStart, errors.Wrap(err, "failed to read has signature data flag")
}
if hasSignatureData {
// Read and discard the data
_, err = ReadLong(buffer) // Expiration time
if err != nil {
return loginStart, errors.Wrap(err, "failed to read expiration time")
}
pubKeyLength, err := ReadVarInt(buffer) // Length of the public key
if err != nil {
return loginStart, errors.Wrap(err, "failed to read public key length")
}
_, err = ReadByteArray(buffer, pubKeyLength) // Public key data
if err != nil {
return loginStart, errors.Wrap(err, "failed to read public key")
}
signatureLength, err := ReadVarInt(buffer) // Length of the signature
if err != nil {
return loginStart, errors.Wrap(err, "failed to read signature length")
}
_, err = ReadByteArray(buffer, signatureLength) // Signature data
if err != nil {
return loginStart, errors.Wrap(err, "failed to read signature")
}
}
}
// References:
// * https://github.com/MCCTeam/Minecraft-Console-Client/blob/f785f509f228bf787c237ac139e6f666a960819a/MinecraftClient/Protocol/Handlers/Protocol18.cs#L2831-L2853
// * https://minecraft.wiki/w/Minecraft_Wiki:Projects/wiki.vg_merge/Protocol?oldid=2772944#Login_Start
switch {
case protocolVersion >= ProtocolVersion1_19_2 && protocolVersion < ProtocolVersion1_20_2:
// Check to see if a UUID was provided at all
hasUUID, err := ReadBoolean(buffer)
if err != nil {
return loginStart, errors.Wrap(err, "failed to read has uuid flag")
}
if !hasUUID {
break
}
fallthrough
case protocolVersion >= ProtocolVersion1_20_2:
// For 1.20.2 and later, the UUID is always present
playerUuid, err := ReadUuid(buffer)
if err != nil {
return loginStart, errors.Wrap(err, "failed to read player uuid")
}
loginStart.PlayerUuid = playerUuid
default:
// For versions before 1.19.2, the UUID is not present
}
return loginStart, nil
}
mcproto/handshake-login-start-1.18.2.hex
+2
View File
@@ -0,0 +1,2 @@
1000f605096c6f63616c686f737463dd02
06000469747a67
mcproto/handshake-login-start-1.19.2-all-info.hex
+2
View File
@@ -0,0 +1,2 @@
1000f805096c6f63616c686f737463dd02
27000469747a670100fefdfc0102030402fbfa03f9f8f7015cddfd26fc864981b52ec42bb10bfdef
mcproto/handshake-login-start-1.19.2-min-info.hex
+2
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@@ -0,0 +1,2 @@
1000f805096c6f63616c686f737463dd02
08000469747a670000
mcproto/handshake-login-start.hex → mcproto/handshake-login-start-1.21.5.hex
View File
mcproto/read.go
+45 -1
View File
@@ -6,12 +6,13 @@ import (
"bufio"
"bytes"
"encoding/binary"
"github.com/google/uuid"
"io"
"net"
"strings"
"time"
"github.com/google/uuid"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/text/encoding/unicode"
@@ -104,11 +105,17 @@ func ReadLegacyServerListPing(reader *bufio.Reader, addr net.Addr) (*Packet, err
}
messageName, err := ReadUTF16BEString(reader, messageNameShortLen)
if err != nil {
return nil, err
}
if messageName != "MC|PingHost" {
return nil, errors.Errorf("expected messageName=MC|PingHost, got %s", messageName)
}
remainingLen, err := ReadUnsignedShort(reader)
if err != nil {
return nil, err
}
remainingReader := io.LimitReader(reader, int64(remainingLen))
protocolVersion, err := ReadByte(remainingReader)
@@ -238,6 +245,21 @@ func ReadVarInt(reader io.Reader) (int, error) {
return 0, errors.New("VarInt is too big")
}
func ReadBoolean(reader io.Reader) (bool, error) {
byteVal, err := ReadByte(reader)
if err != nil {
return false, err
}
switch byteVal {
case 0x00:
return false, nil
case 0x01:
return true, nil
default:
return false, errors.Errorf("expected 0x00 or 0x01 for boolean, got 0x%02X", byteVal)
}
}
func ReadString(reader io.Reader) (string, error) {
length, err := ReadVarInt(reader)
if err != nil {
@@ -270,6 +292,19 @@ func ReadByte(reader io.Reader) (byte, error) {
}
}
func ReadByteArray(reader io.Reader, length int) ([]byte, error) {
if length < 0 {
return nil, errors.New("length cannot be negative")
}
data := make([]byte, length)
_, err := io.ReadFull(reader, data)
if err != nil {
return nil, err
}
return data, nil
}
func ReadUnsignedShort(reader io.Reader) (uint16, error) {
var value uint16
err := binary.Read(reader, binary.BigEndian, &value)
@@ -288,6 +323,15 @@ func ReadUnsignedInt(reader io.Reader) (uint32, error) {
return value, nil
}
func ReadLong(reader io.Reader) (int64, error) {
var value int64
err := binary.Read(reader, binary.BigEndian, &value)
if err != nil {
return 0, err
}
return value, nil
}
func ReadUuid(reader io.Reader) (uuid.UUID, error) {
uuidBytes := make([]byte, 16)
_, err := io.ReadFull(reader, uuidBytes)
mcproto/read_test.go
+49 -7
View File
@@ -5,12 +5,13 @@ import (
"bytes"
"encoding/hex"
"fmt"
"github.com/google/uuid"
"os"
"strings"
"testing"
"unicode"
"github.com/google/uuid"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
@@ -57,12 +58,51 @@ func TestHandshakeThenStatus(t *testing.T) {
assert.Equal(t, "localhost", handshake.ServerAddress)
assert.Equal(t, uint16(25565), handshake.ServerPort)
assert.Equal(t, 770 /*for 1.21.5*/, handshake.ProtocolVersion)
assert.Equal(t, ProtocolVersion1_21_5, handshake.ProtocolVersion)
assert.Equal(t, StateStatus, handshake.NextState)
}
func TestHandshakeThenLoginStart(t *testing.T) {
content, err := ReadHexDumpFile("handshake-login-start.hex")
func TestHandshakeThenLoginStartVersion(t *testing.T) {
playerUuid := uuid.MustParse("5cddfd26-fc86-4981-b52e-c42bb10bfdef")
tests := []struct {
Name string
Filename string
ExpectedProtocolVersion ProtocolVersion
ExpectedPlayerUuid uuid.UUID
}{
{
Name: "1.20.2",
Filename: "handshake-login-start-1.21.5.hex",
ExpectedProtocolVersion: ProtocolVersion1_21_5,
ExpectedPlayerUuid: playerUuid,
},
// This version only conditionally provides a UUID, and may provide other information
// as well
{
Name: "1.19.2-all-info",
Filename: "handshake-login-start-1.19.2-all-info.hex",
ExpectedProtocolVersion: ProtocolVersion1_19_2,
ExpectedPlayerUuid: playerUuid,
},
{
Name: "1.19.2-min-info",
Filename: "handshake-login-start-1.19.2-min-info.hex",
ExpectedProtocolVersion: ProtocolVersion1_19_2,
ExpectedPlayerUuid: uuid.Nil, // No UUID provided in this case
},
// This is the last version that does not provide a UUID
{
Name: "1.18.2",
Filename: "handshake-login-start-1.18.2.hex",
ExpectedProtocolVersion: ProtocolVersion1_18_2,
ExpectedPlayerUuid: uuid.Nil, // No UUID provided by this version
},
}
for _, tt := range tests {
t.Run(tt.Name, func(t *testing.T) {
content, err := ReadHexDumpFile(tt.Filename)
require.NoError(t, err)
reader := bufio.NewReader(bytes.NewReader(content))
@@ -75,17 +115,19 @@ func TestHandshakeThenLoginStart(t *testing.T) {
assert.Equal(t, "localhost", handshake.ServerAddress)
assert.Equal(t, uint16(25565), handshake.ServerPort)
assert.Equal(t, 770 /*for 1.21.5*/, handshake.ProtocolVersion)
assert.Equal(t, tt.ExpectedProtocolVersion, handshake.ProtocolVersion)
assert.Equal(t, StateLogin, handshake.NextState)
loginStartPacket, err := ReadPacket(reader, nil, StateLogin)
require.NoError(t, err)
loginStart, err := DecodeLoginStart(loginStartPacket.Data)
loginStart, err := DecodeLoginStart(handshake.ProtocolVersion, loginStartPacket.Data)
require.NoError(t, err)
assert.Equal(t, "itzg", loginStart.Name)
assert.Equal(t, uuid.MustParse("5cddfd26-fc86-4981-b52e-c42bb10bfdef"), loginStart.PlayerUuid)
assert.Equal(t, tt.ExpectedPlayerUuid, loginStart.PlayerUuid)
})
}
}
func ReadHexDumpFile(filename string) ([]byte, error) {
mcproto/types.go
+30 -1
View File
@@ -2,6 +2,7 @@ package mcproto
import (
"fmt"
"github.com/google/uuid"
)
@@ -53,6 +54,27 @@ func (p *Packet) String() string {
}
}
type ProtocolVersion int
// Source: https://minecraft.wiki/w/Minecraft_Wiki:Projects/wiki.vg_merge/Protocol_History
const (
// ProtocolVersion1_18_2 is the protocol version for Minecraft 1.18.2
// Docs: https://minecraft.wiki/w/Java_Edition_protocol/Packets?oldid=2772791
ProtocolVersion1_18_2 ProtocolVersion = 758
// ProtocolVersion1_19 is the protocol version for Minecraft 1.19
// Docs: https://minecraft.wiki/w/Java_Edition_protocol/Packets?oldid=2772904
ProtocolVersion1_19 ProtocolVersion = 759
// ProtocolVersion1_19_2 is the protocol version for Minecraft 1.19.2
// Docs: https://minecraft.wiki/w/Java_Edition_protocol/Packets?oldid=2772944
ProtocolVersion1_19_2 ProtocolVersion = 760
// ProtocolVersion1_19_2 is the protocol version for Minecraft 1.19.3
ProtocolVersion1_19_3 ProtocolVersion = 761
// ProtocolVersion1_20_2 is the protocol version for Minecraft 1.20.2
ProtocolVersion1_20_2 ProtocolVersion = 764
// ProtocolVersion1_21_5 is the protocol version for Minecraft 1.21.5
ProtocolVersion1_21_5 ProtocolVersion = 770
)
const (
PacketIdHandshake = 0x00
PacketIdLogin = 0x00 // during StateLogin
@@ -60,7 +82,7 @@ const (
)
type Handshake struct {
ProtocolVersion int
ProtocolVersion ProtocolVersion
ServerAddress string
ServerPort uint16
NextState State
@@ -71,6 +93,13 @@ type LoginStart struct {
PlayerUuid uuid.UUID
}
func NewLoginStart() *LoginStart {
return &LoginStart{
// Note: This is indistinguishable between no UUID provided, and a provided UUID of all 0s
PlayerUuid: uuid.Nil,
}
}
type LegacyServerListPing struct {
ProtocolVersion int
ServerAddress string
server/connector.go
+6 -4
View File
@@ -6,13 +6,14 @@ import (
"context"
"errors"
"fmt"
"github.com/google/uuid"
"io"
"net"
"sync"
"sync/atomic"
"time"
"github.com/google/uuid"
"golang.ngrok.com/ngrok"
"golang.ngrok.com/ngrok/config"
@@ -65,6 +66,7 @@ func (p *PlayerInfo) String() string {
if p == nil {
return ""
}
return fmt.Sprintf("%s/%s", p.Name, p.Uuid)
}
@@ -318,7 +320,7 @@ func (c *Connector) HandleConnection(ctx context.Context, frontendConn net.Conn)
var playerInfo *PlayerInfo = nil
if handshake.NextState == mcproto.StateLogin {
playerInfo, err = c.readPlayerInfo(bufferedReader, clientAddr, handshake.NextState)
playerInfo, err = c.readPlayerInfo(handshake.ProtocolVersion, bufferedReader, clientAddr, handshake.NextState)
if err != nil {
if errors.Is(err, io.EOF) {
logrus.
@@ -372,14 +374,14 @@ func (c *Connector) HandleConnection(ctx context.Context, frontendConn net.Conn)
}
}
func (c *Connector) readPlayerInfo(bufferedReader *bufio.Reader, clientAddr net.Addr, state mcproto.State) (*PlayerInfo, error) {
func (c *Connector) readPlayerInfo(protocolVersion mcproto.ProtocolVersion, bufferedReader *bufio.Reader, clientAddr net.Addr, state mcproto.State) (*PlayerInfo, error) {
loginPacket, err := mcproto.ReadPacket(bufferedReader, clientAddr, state)
if err != nil {
return nil, fmt.Errorf("failed to read login packet: %w", err)
}
if loginPacket.PacketID == mcproto.PacketIdLogin {
loginStart, err := mcproto.DecodeLoginStart(loginPacket.Data)
loginStart, err := mcproto.DecodeLoginStart(protocolVersion, loginPacket.Data)
if err != nil {
return nil, fmt.Errorf("failed to decode login start: %w", err)
}