252 lines
9.7 KiB
Go
252 lines
9.7 KiB
Go
package udp
|
|
|
|
import (
|
|
"crypto/rc4"
|
|
"errors"
|
|
"fmt"
|
|
)
|
|
|
|
// CRC32 lookup table for polynomial 0xEDB88320 (IEEE 802.3 standard)
|
|
var crcTable = [256]uint32{
|
|
0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
|
|
0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
|
|
0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
|
|
0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
|
|
0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
|
|
0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
|
|
0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
|
|
0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
|
|
0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
|
|
0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
|
|
0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
|
|
0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
|
|
0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
|
|
0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
|
|
0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
|
|
0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
|
|
0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
|
|
0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
|
|
0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
|
|
0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
|
|
0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
|
|
0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
|
|
0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
|
|
0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
|
|
0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
|
|
0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
|
|
0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
|
|
0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
|
|
0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
|
|
0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
|
|
0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
|
|
0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D,
|
|
}
|
|
|
|
// CRC16 computes CRC32 checksum with custom key initialization for EQ2 protocol
|
|
// This function implements the reverse-engineered CRC calculation used in EQ2
|
|
// despite being named CRC16, it actually performs 32-bit CRC calculation
|
|
func CRC16(buf []byte, key uint32) uint32 {
|
|
crc := key // Initialize with provided key
|
|
|
|
// Pre-process the key through multiple CRC table lookups
|
|
// This mirrors the original assembly implementation's key initialization
|
|
crc = ^crc // Invert initial key
|
|
crc &= 0xFF // Mask to lowest byte
|
|
crc = crcTable[crc] // First table lookup
|
|
crc ^= 0x00FFFFFF // XOR with mask
|
|
|
|
// Process second byte of original key
|
|
temp := key >> 8 // Shift key right 8 bits
|
|
temp ^= crc // XOR with current CRC
|
|
crc >>= 8 // Shift CRC right 8 bits
|
|
temp &= 0xFF // Mask to byte
|
|
crc &= 0x00FFFFFF // Mask CRC to 24 bits
|
|
crc ^= crcTable[temp] // Second table lookup
|
|
|
|
// Process third byte of original key
|
|
temp = key >> 16 // Shift key right 16 bits
|
|
temp ^= crc // XOR with current CRC
|
|
crc >>= 8 // Shift CRC right 8 bits
|
|
temp &= 0xFF // Mask to byte
|
|
temp2 := crcTable[temp] // Third table lookup
|
|
crc &= 0x00FFFFFF // Mask CRC to 24 bits
|
|
crc ^= temp2 // XOR with lookup result
|
|
|
|
// Process fourth byte of original key
|
|
fourthByte := key >> 24 // Extract highest byte
|
|
fourthByte ^= crc // XOR with current CRC
|
|
fourthByte &= 0xFF // Mask to byte
|
|
temp2 = crcTable[fourthByte] // Fourth table lookup
|
|
crc >>= 8 // Shift CRC right 8 bits
|
|
crc &= 0x00FFFFFF // Mask CRC to 24 bits
|
|
crc ^= temp2 // XOR with lookup result
|
|
|
|
// Process each byte in the input buffer
|
|
for _, b := range buf {
|
|
byteVal := uint32(b) & 0xFF // Extract current byte
|
|
byteVal ^= crc // XOR byte with current CRC
|
|
crc >>= 8 // Shift CRC right 8 bits
|
|
byteVal &= 0xFF // Ensure byte is masked
|
|
lookup := crcTable[byteVal] // Table lookup for this byte
|
|
crc &= 0x00FFFFFF // Mask CRC to 24 bits
|
|
crc ^= lookup // XOR with lookup result
|
|
}
|
|
|
|
return ^crc // Return inverted final CRC
|
|
}
|
|
|
|
// ValidateCRCWithKey checks if packet has valid CRC using the provided key
|
|
// Expects CRC to be the last 2 bytes of data
|
|
func ValidateCRCWithKey(data []byte, key uint32) bool {
|
|
if len(data) < 4 { // Need at least [header][opcode][data][CRC][CRC]
|
|
return false
|
|
}
|
|
|
|
// The CRC should be calculated on the serialized packet (opcode + data), excluding header and CRC
|
|
// EQ2 packet format: [header][opcode][data...][CRC16]
|
|
// CRC covers: [opcode][data...] (starting from byte 1, excluding header and CRC)
|
|
payload := data[1 : len(data)-2] // Skip header, include opcode, exclude CRC
|
|
expectedCRC := uint16(data[len(data)-1])<<8 | uint16(data[len(data)-2]) // Big-endian CRC
|
|
|
|
// Calculate and compare
|
|
actualCRC := uint16(CRC16(payload, key))
|
|
|
|
// Debug output
|
|
fmt.Printf("CRC Debug - Key: 0x%08X, Expected: 0x%04X, Actual: 0x%04X, Match: %v\n",
|
|
key, expectedCRC, actualCRC, expectedCRC == actualCRC)
|
|
fmt.Printf("CRC payload (%d bytes): ", len(payload))
|
|
for i, b := range payload {
|
|
fmt.Printf("%02X ", b)
|
|
if i > 0 && (i+1)%16 == 0 {
|
|
fmt.Printf("\n ")
|
|
}
|
|
}
|
|
fmt.Printf("\n")
|
|
|
|
return expectedCRC == actualCRC
|
|
}
|
|
|
|
// ValidateCRC checks if packet has valid CRC using default key (0)
|
|
// Expects CRC to be the last 2 bytes of data
|
|
func ValidateCRC(data []byte) bool {
|
|
return ValidateCRCWithKey(data, 0)
|
|
}
|
|
|
|
// AppendCRCWithKey adds 16-bit CRC to the end of data using the provided key
|
|
func AppendCRCWithKey(data []byte, key uint32) []byte {
|
|
crc := uint16(CRC16(data, key))
|
|
result := make([]byte, len(data)+2)
|
|
copy(result, data)
|
|
|
|
// Append CRC in big-endian format (as per C++ htons)
|
|
result[len(data)] = byte(crc)
|
|
result[len(data)+1] = byte(crc >> 8)
|
|
|
|
return result
|
|
}
|
|
|
|
// AppendCRC adds 16-bit CRC to the end of data using default key (0)
|
|
func AppendCRC(data []byte) []byte {
|
|
return AppendCRCWithKey(data, 0)
|
|
}
|
|
|
|
// ValidateAndStrip validates CRC and returns data without CRC suffix
|
|
func ValidateAndStrip(data []byte) ([]byte, bool) {
|
|
if !ValidateCRC(data) {
|
|
return nil, false
|
|
}
|
|
return data[:len(data)-2], true
|
|
}
|
|
|
|
// Crypto handles RC4 encryption/decryption for EQ2EMu protocol
|
|
type Crypto struct {
|
|
clientCipher *rc4.Cipher // Cipher for decrypting client data
|
|
serverCipher *rc4.Cipher // Cipher for encrypting server data
|
|
key []byte // Encryption key
|
|
encrypted bool // Whether encryption is active
|
|
}
|
|
|
|
// NewCrypto creates a new crypto instance with encryption disabled
|
|
func NewCrypto() *Crypto {
|
|
return &Crypto{}
|
|
}
|
|
|
|
// SetKey initializes RC4 encryption with the given key
|
|
// Creates separate ciphers for client and server with 20-byte priming
|
|
func (c *Crypto) SetKey(key []byte) error {
|
|
if len(key) == 0 {
|
|
return errors.New("encryption key cannot be empty")
|
|
}
|
|
|
|
// Create separate RC4 ciphers for bidirectional communication
|
|
clientCipher, err := rc4.NewCipher(key)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
serverCipher, err := rc4.NewCipher(key)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Prime both ciphers with 20 dummy bytes per EQ2EMu protocol
|
|
dummy := make([]byte, 20)
|
|
clientCipher.XORKeyStream(dummy, dummy)
|
|
serverCipher.XORKeyStream(dummy, dummy)
|
|
|
|
c.clientCipher = clientCipher
|
|
c.serverCipher = serverCipher
|
|
c.key = make([]byte, len(key))
|
|
copy(c.key, key)
|
|
c.encrypted = true
|
|
|
|
return nil
|
|
}
|
|
|
|
// IsEncrypted returns whether encryption is currently active
|
|
func (c *Crypto) IsEncrypted() bool {
|
|
return c.encrypted
|
|
}
|
|
|
|
// Encrypt encrypts data for transmission to client
|
|
func (c *Crypto) Encrypt(data []byte) []byte {
|
|
if !c.encrypted || c.serverCipher == nil {
|
|
return data
|
|
}
|
|
|
|
encrypted := make([]byte, len(data))
|
|
copy(encrypted, data)
|
|
c.serverCipher.XORKeyStream(encrypted, encrypted)
|
|
return encrypted
|
|
}
|
|
|
|
// Decrypt decrypts data received from client
|
|
func (c *Crypto) Decrypt(data []byte) []byte {
|
|
if !c.encrypted || c.clientCipher == nil {
|
|
return data
|
|
}
|
|
|
|
decrypted := make([]byte, len(data))
|
|
copy(decrypted, data)
|
|
c.clientCipher.XORKeyStream(decrypted, decrypted)
|
|
return decrypted
|
|
}
|
|
|
|
// GetKey returns a copy of the encryption key
|
|
func (c *Crypto) GetKey() []byte {
|
|
if c.key == nil {
|
|
return nil
|
|
}
|
|
keyCopy := make([]byte, len(c.key))
|
|
copy(keyCopy, c.key)
|
|
return keyCopy
|
|
}
|
|
|
|
// Reset disables encryption and clears keys
|
|
func (c *Crypto) Reset() {
|
|
c.clientCipher = nil
|
|
c.serverCipher = nil
|
|
c.key = nil
|
|
c.encrypted = false
|
|
}
|