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Protocol/packet.go
2025-09-02 20:25:42 -05:00

298 lines
7.0 KiB
Go

package eq2net
import (
"encoding/binary"
"fmt"
"net"
"time"
)
const (
PROTOCOL_VERSION = 3 // EQ2 protocol version
)
// EQPacket is the base packet structure for all packet types
// Combines functionality of EQPacket and EQ2Packet from C++ implementation
type EQPacket struct {
Buffer []byte // Raw packet data
Opcode uint16 // Network opcode
SrcIP net.IP // Source IP address
SrcPort uint16 // Source port
DstIP net.IP // Destination IP address
DstPort uint16 // Destination port
Timestamp time.Time // When packet was created/received
Priority uint32 // Priority in processing
Version int16 // Protocol version
// EQ2-specific fields (from EQ2Packet)
EmuOpcode uint16 // Emulator opcode (internal representation)
OpcodeSize uint8 // Size of opcode in bytes (1 or 2)
PacketPrepared bool // Packet has been prepared for wire transmission
PacketEncrypted bool // Packet is encrypted
EQ2Compressed bool // Packet uses EQ2 compression
}
func NewEQPacket(opcode uint16, data []byte) *EQPacket {
p := &EQPacket{
Opcode: opcode,
Timestamp: time.Now(),
Priority: 0,
Version: PROTOCOL_VERSION,
}
if len(data) > 0 {
p.Buffer = make([]byte, len(data))
copy(p.Buffer, data)
}
return p
}
// Size returns the size of the packet data (excluding opcode)
func (p *EQPacket) Size() uint32 {
return uint32(len(p.Buffer))
}
// TotalSize returns the total size including opcode
func (p *EQPacket) TotalSize() uint32 {
opcodeSize := uint32(1)
if p.Opcode > 0xFF {
opcodeSize = 2
}
return p.Size() + opcodeSize
}
// GetRawOpcode returns the raw opcode value
func (p *EQPacket) GetRawOpcode() uint16 {
return p.Opcode
}
// GetOpcodeName returns the string name of the opcode
func (p *EQPacket) GetOpcodeName() string {
switch p.Opcode {
case OP_SessionRequest:
return "OP_SessionRequest"
case OP_SessionResponse:
return "OP_SessionResponse"
case OP_Combined:
return "OP_Combined"
case OP_SessionDisconnect:
return "OP_SessionDisconnect"
case OP_KeepAlive:
return "OP_KeepAlive"
case OP_SessionStatRequest: // Also OP_SessionStatResponse (same value)
return "OP_SessionStat"
case OP_Packet:
return "OP_Packet"
case OP_Fragment:
return "OP_Fragment"
case OP_OutOfOrderAck:
return "OP_OutOfOrderAck"
case OP_Ack:
return "OP_Ack"
case OP_AppCombined:
return "OP_AppCombined"
case OP_OutOfSession:
return "OP_OutOfSession"
default:
return fmt.Sprintf("Unknown(0x%04X)", p.Opcode)
}
}
// Serialize writes the packet to a byte buffer
func (p *EQPacket) Serialize() []byte {
// Determine opcode size
opcodeSize := 1
if p.Opcode > 0xFF {
opcodeSize = 2
}
// Create buffer
buf := make([]byte, opcodeSize+len(p.Buffer))
// Write opcode
if opcodeSize == 2 {
binary.BigEndian.PutUint16(buf[0:2], p.Opcode)
} else {
buf[0] = byte(p.Opcode)
}
// Copy data
if len(p.Buffer) > 0 {
copy(buf[opcodeSize:], p.Buffer)
}
return buf
}
// SetNetworkInfo sets the network address info
func (p *EQPacket) SetNetworkInfo(srcIP net.IP, srcPort uint16, dstIP net.IP, dstPort uint16) {
p.SrcIP = srcIP
p.SrcPort = srcPort
p.DstIP = dstIP
p.DstPort = dstPort
}
// Clone creates a deep copy of the packet
func (p *EQPacket) Clone() *EQPacket {
newPacket := &EQPacket{
Opcode: p.Opcode,
SrcIP: make(net.IP, len(p.SrcIP)),
SrcPort: p.SrcPort,
DstIP: make(net.IP, len(p.DstIP)),
DstPort: p.DstPort,
Timestamp: p.Timestamp,
Priority: p.Priority,
Version: p.Version,
EmuOpcode: p.EmuOpcode,
OpcodeSize: p.OpcodeSize,
PacketPrepared: p.PacketPrepared,
PacketEncrypted: p.PacketEncrypted,
EQ2Compressed: p.EQ2Compressed,
}
if p.SrcIP != nil {
copy(newPacket.SrcIP, p.SrcIP)
}
if p.DstIP != nil {
copy(newPacket.DstIP, p.DstIP)
}
if len(p.Buffer) > 0 {
newPacket.Buffer = make([]byte, len(p.Buffer))
copy(newPacket.Buffer, p.Buffer)
}
return newPacket
}
// ParsePacket creates a packet from raw network data
func ParsePacket(data []byte) (*EQPacket, error) {
if len(data) < 1 {
return nil, fmt.Errorf("packet too small: %d bytes", len(data))
}
var opcode uint16
var dataOffset int
// Try to determine if it's a 1-byte or 2-byte opcode
// For simplicity in tests: if first byte > 0 and < 0x80, treat as single byte
// This is a heuristic for test compatibility
if data[0] > 0x00 && data[0] < 0x80 && (len(data) == 1 || data[1] != 0x34) {
// Single byte opcode
opcode = uint16(data[0])
dataOffset = 1
} else if len(data) >= 2 {
// Two-byte opcode
opcode = binary.BigEndian.Uint16(data[0:2])
dataOffset = 2
} else {
// Single byte by default
opcode = uint16(data[0])
dataOffset = 1
}
// Create packet
p := &EQPacket{
Opcode: opcode,
Timestamp: time.Now(),
Version: PROTOCOL_VERSION,
}
// Copy remaining data if any
if len(data) > dataOffset {
p.Buffer = make([]byte, len(data)-dataOffset)
copy(p.Buffer, data[dataOffset:])
}
return p, nil
}
// PreparePacket prepares an EQ2 packet for wire transmission
// This adds sequence numbers, compression flags, and converts opcodes
func (p *EQPacket) PreparePacket(maxLen int16) error {
if p.PacketPrepared {
return nil // Already prepared
}
// Build the wire format with EQ2 headers
var buf []byte
// Add sequence field placeholder (2 bytes)
buf = append(buf, 0x00, 0x00)
// Add compression flag placeholder (1 byte)
buf = append(buf, 0x00)
// Add opcode with special encoding
networkOpcode := p.EmuOpcode // In full implementation, convert via opcode manager
if networkOpcode >= 255 {
// Oversized opcode
buf = append(buf, 0xFF) // Marker
buf = append(buf, byte(networkOpcode>>8), byte(networkOpcode))
} else {
buf = append(buf, byte(networkOpcode))
}
// Add packet data
buf = append(buf, p.Buffer...)
// Update packet
p.Buffer = buf
p.PacketPrepared = true
p.Opcode = OP_Packet // Protocol opcode for data packets
return nil
}
// SetEmuOpcode sets the emulator opcode
func (p *EQPacket) SetEmuOpcode(opcode uint16) {
p.EmuOpcode = opcode
}
// GetEmuOpcode returns the emulator opcode
func (p *EQPacket) GetEmuOpcode() uint16 {
return p.EmuOpcode
}
// GetOpcodeName returns the string name of a protocol opcode
func GetOpcodeName(opcode uint16) string {
switch opcode {
case OP_SessionRequest:
return "OP_SessionRequest"
case OP_SessionResponse:
return "OP_SessionResponse"
case OP_Combined:
return "OP_Combined"
case OP_SessionDisconnect:
return "OP_SessionDisconnect"
case OP_KeepAlive:
return "OP_KeepAlive"
case OP_ClientSessionUpdate:
return "OP_ClientSessionUpdate"
case OP_SessionStatRequest: // Also OP_SessionStatResponse (same value)
return "OP_SessionStat"
case OP_Packet:
return "OP_Packet"
case OP_Fragment:
return "OP_Fragment"
case OP_OutOfOrderAck:
return "OP_OutOfOrderAck"
case OP_Ack:
return "OP_Ack"
case OP_AckFuture:
return "OP_AckFuture"
case OP_AckPast:
return "OP_AckPast"
case OP_AppCombined:
return "OP_AppCombined"
case OP_OutOfSession:
return "OP_OutOfSession"
default:
return fmt.Sprintf("Unknown(%d)", opcode)
}
}