Finalmask: Add XMC (TCP, Minecraft)

infra/conf/transport_finalmask.go

@@ -1,9 +1,11 @@
 package conf
 
 import (
+	"crypto/x509"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"net/netip"
 	"net/url"
 	"regexp"
@@ -22,6 +24,7 @@ import (
 	"github.com/xtls/xray-core/transport/internet/finalmask/sudoku"
 	"github.com/xtls/xray-core/transport/internet/finalmask/xdns"
 	"github.com/xtls/xray-core/transport/internet/finalmask/xicmp"
+	"github.com/xtls/xray-core/transport/internet/finalmask/xmc"
 	"github.com/xtls/xray-core/transport/internet/tls"
 	"google.golang.org/protobuf/proto"
 )
@@ -67,6 +70,7 @@ var (
 		"header-custom": func() interface{} { return new(HeaderCustomTCP) },
 		"fragment":      func() interface{} { return new(FragmentMask) },
 		"sudoku":        func() interface{} { return new(Sudoku) },
+		"xmc":           func() interface{} { return new(XMC) },
 	}, "type", "settings")
 
 	udpmaskLoader = NewJSONConfigLoader(ConfigCreatorCache{
@@ -715,6 +719,40 @@ func (c *Xdns) Build() (proto.Message, error) {
 	}, nil
 }
 
+type XMC struct {
+	Hostname  string   `json:"hostname"`
+	Usernames []string `json:"usernames"`
+	Password  string   `json:"password"`
+}
+
+func (c *XMC) Build() (proto.Message, error) {
+	if len(c.Usernames) == 0 {
+		c.Usernames = []string{"Dream"}
+	}
+
+	if c.Password == "" {
+		return nil, fmt.Errorf("empty password")
+	}
+
+	rsaPrivateKey, err := xmc.DeriveRSAKey(c.Password)
+	if err != nil {
+		return nil, fmt.Errorf("derive minecraft rsa key: %w", err)
+	}
+
+	rsaPublicKey, err := x509.MarshalPKIXPublicKey(&rsaPrivateKey.PublicKey)
+	if err != nil {
+		return nil, fmt.Errorf("marshal minecraft rsa public key: %w", err)
+	}
+
+	return &xmc.Config{
+		Password:      c.Password,
+		Usernames:     c.Usernames,
+		Hostname:      c.Hostname,
+		RsaPrivateKey: x509.MarshalPKCS1PrivateKey(rsaPrivateKey),
+		RsaPublicKey:  rsaPublicKey,
+	}, nil
+}
+
 type Xicmp struct {
 	DGRAM bool     `json:"dgram"`
 	IPs   []string `json:"ips"`

transport/internet/finalmask/xmc/cfb8.go

@@ -0,0 +1,138 @@
+package xmc
+
+// Copied from https://github.com/Tnze/go-mc/blob/539b4a3a7f030332eb58b8a946116ae7907630d2/net/CFB8/cfb8.go
+
+import (
+	"crypto/cipher"
+	"crypto/subtle"
+	"unsafe"
+)
+
+type cfb8 struct {
+	c         cipher.Block
+	blockSize int
+	ivPos     int
+	iv        []byte
+	de        bool
+}
+
+func newCFB8Decrypt(c cipher.Block, iv []byte) *cfb8 {
+	return newCFB8(c, iv, true)
+}
+
+func newCFB8Encrypt(c cipher.Block, iv []byte) *cfb8 {
+	return newCFB8(c, iv, false)
+}
+
+func newCFB8(c cipher.Block, iv []byte, de bool) *cfb8 {
+	cp := make([]byte, len(iv)*3)
+	copy(cp, iv)
+	return &cfb8{
+		c:         c,
+		blockSize: c.BlockSize(),
+		iv:        cp,
+		de:        de,
+	}
+}
+
+func (cf *cfb8) XORKeyStream(dst, src []byte) {
+	if len(src) == 0 {
+		return
+	}
+	if len(dst) < len(src) {
+		panic("cfb8: output smaller than input")
+	}
+
+	// If dst and src does not overlap in first block size,
+	// and the length of src is greater than 2*blockSize,
+	// we can use an optimized implementation.
+	if len(src) > cf.blockSize<<1 &&
+		(uintptr(unsafe.Pointer(&dst[0]))+uintptr(cf.blockSize) <= uintptr(unsafe.Pointer(&src[0])) ||
+			uintptr(unsafe.Pointer(&src[0]))+uintptr(len(src)) <= uintptr(unsafe.Pointer(&dst[0]))) {
+		// encrypt/decrypt first blockSize bytes
+		// After this, the IV will come to the same as
+		// the last blockSize of ciphertext, so
+		// we can reuse them without copy.
+		cf.xorKeyStream(dst, src[:cf.blockSize])
+		var ciphertext []byte
+		if cf.de {
+			ciphertext = src
+		} else {
+			ciphertext = dst
+		}
+		dst = dst[cf.blockSize:]
+		src = src[cf.blockSize:]
+		iv := cf.iv
+		_ = iv[0] // bounds check hint to compiler; see golang.org/issue/14808
+		var (
+			i   int
+			val byte
+		)
+		dst = dst[:len(src)]
+		if cf.de && // and requires to be non-overlapping at all
+			uintptr(unsafe.Pointer(&dst[0])) <= uintptr(unsafe.Pointer(&src[len(src)-1])) &&
+			uintptr(unsafe.Pointer(&src[0])) <= uintptr(unsafe.Pointer(&dst[len(dst)-1])) {
+			for i = 0; i < len(src)-cf.blockSize; i += 1 {
+				cf.c.Encrypt(dst[i:], ciphertext[i:])
+			}
+			subtle.XORBytes(dst, src[:i], dst)
+			for ; i < len(src); i += 1 {
+				cf.c.Encrypt(iv, ciphertext[i:])
+				dst[i] = src[i] ^ iv[0]
+			}
+		} else {
+			_ = ciphertext[len(src)]
+			for i, val = range src {
+				cf.c.Encrypt(iv, ciphertext[i:])
+				dst[i] = val ^ iv[0]
+			}
+			// for-range does not increase i in the last loop,
+			// compared to the classic for clause
+			i += 1
+		}
+		// copy the current IV for next operation
+		copy(iv, ciphertext[i:i+cf.blockSize])
+		cf.ivPos = 0
+		return
+	}
+
+	cf.xorKeyStream(dst, src)
+}
+
+func (cf *cfb8) xorKeyStream(dst, src []byte) {
+	dst = dst[:len(src)] // remove bounds check in loop
+	for i, val := range src {
+		posPlusBlockSize := cf.ivPos + cf.blockSize
+		// fast mod; 2*blockSize must be a non-negative integer power of 2
+		tempPos := posPlusBlockSize & (cf.blockSize<<1 - 1)
+		// reuse space to store encrypted block
+		cf.c.Encrypt(cf.iv[tempPos:], cf.iv[cf.ivPos:])
+		// Only the first byte of the encrypted block is used
+		// for encryption/decryption, other bytes are ignored.
+		val ^= cf.iv[tempPos]
+
+		if cf.ivPos == cf.blockSize<<1 {
+			// bound reached; move to next round for next operation
+			// copy next block to the start of the ring buffer
+			copy(cf.iv, cf.iv[cf.ivPos+1:])
+			// insert the encrypted byte to the end of IV
+			if cf.de {
+				cf.iv[cf.blockSize-1] = src[i]
+			} else {
+				cf.iv[cf.blockSize-1] = val
+			}
+			cf.ivPos = 0
+		} else {
+			// insert the encrypted byte to the end of IV
+			if cf.de {
+				cf.iv[posPlusBlockSize] = src[i]
+			} else {
+				cf.iv[posPlusBlockSize] = val
+			}
+			// move to next block
+			cf.ivPos += 1
+		}
+
+		dst[i] = val
+	}
+}