Finalmask: Add XDNS (relies mKCP, like DNSTT), header-*, mkcp-* (#5560)

And https://github.com/XTLS/Xray-core/pull/5560#issuecomment-3825430761

transport/internet/finalmask/salamander/conn.go

@@ -0,0 +1,147 @@
+package salamander
+
+import (
+	"io"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/xtls/xray-core/common/errors"
+)
+
+type obfsPacketConn struct {
+	first     bool
+	leaveSize int32
+
+	conn net.PacketConn
+	obfs *SalamanderObfuscator
+
+	readBuf    []byte
+	readMutex  sync.Mutex
+	writeBuf   []byte
+	writeMutex sync.Mutex
+}
+
+func NewConnClient(c *Config, raw net.PacketConn, first bool, leaveSize int32) (net.PacketConn, error) {
+	ob, err := NewSalamanderObfuscator([]byte(c.Password))
+	if err != nil {
+		return nil, errors.New("salamander err").Base(err)
+	}
+
+	conn := &obfsPacketConn{
+		first:     first,
+		leaveSize: leaveSize,
+
+		conn: raw,
+		obfs: ob,
+	}
+
+	if first {
+		conn.readBuf = make([]byte, 8192)
+		conn.writeBuf = make([]byte, 8192)
+	}
+
+	return conn, nil
+}
+
+func NewConnServer(c *Config, raw net.PacketConn, first bool, leaveSize int32) (net.PacketConn, error) {
+	return NewConnClient(c, raw, first, leaveSize)
+}
+
+func (c *obfsPacketConn) Size() int32 {
+	return smSaltLen
+}
+
+func (c *obfsPacketConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
+	if c.first {
+		c.readMutex.Lock()
+
+		n, addr, err = c.conn.ReadFrom(c.readBuf)
+		if err != nil {
+			c.readMutex.Unlock()
+			return n, addr, err
+		}
+
+		if n < int(c.Size()) {
+			c.readMutex.Unlock()
+			return 0, addr, errors.New("salamander").Base(io.ErrShortBuffer)
+		}
+
+		if len(p) < n-int(c.Size()) {
+			c.readMutex.Unlock()
+			return 0, addr, errors.New("salamander").Base(io.ErrShortBuffer)
+		}
+
+		c.obfs.Deobfuscate(c.readBuf[:n], p)
+
+		c.readMutex.Unlock()
+		return n - int(c.Size()), addr, err
+	}
+
+	n, addr, err = c.conn.ReadFrom(p)
+	if err != nil {
+		return n, addr, err
+	}
+
+	if n < int(c.Size()) {
+		return 0, addr, errors.New("salamander").Base(io.ErrShortBuffer)
+	}
+
+	c.obfs.Deobfuscate(p[:n], p)
+
+	return n - int(c.Size()), addr, err
+}
+
+func (c *obfsPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	if c.first {
+		if c.leaveSize+c.Size()+int32(len(p)) > 8192 {
+			return 0, errors.New("too many masks")
+		}
+
+		c.writeMutex.Lock()
+
+		n = copy(c.writeBuf[c.leaveSize+c.Size():], p)
+		n += int(c.leaveSize) + int(c.Size())
+
+		c.obfs.Obfuscate(c.writeBuf[c.leaveSize+c.Size():n], c.writeBuf[c.leaveSize:n])
+
+		nn, err := c.conn.WriteTo(c.writeBuf[:n], addr)
+
+		if err != nil {
+			c.writeMutex.Unlock()
+			return 0, err
+		}
+
+		if nn != n {
+			c.writeMutex.Unlock()
+			return 0, errors.New("nn != n")
+		}
+
+		c.writeMutex.Unlock()
+		return len(p), nil
+	}
+
+	c.obfs.Obfuscate(p[c.leaveSize+c.Size():], p[c.leaveSize:])
+
+	return c.conn.WriteTo(p, addr)
+}
+
+func (c *obfsPacketConn) Close() error {
+	return c.conn.Close()
+}
+
+func (c *obfsPacketConn) LocalAddr() net.Addr {
+	return c.conn.LocalAddr()
+}
+
+func (c *obfsPacketConn) SetDeadline(t time.Time) error {
+	return c.conn.SetDeadline(t)
+}
+
+func (c *obfsPacketConn) SetReadDeadline(t time.Time) error {
+	return c.conn.SetReadDeadline(t)
+}
+
+func (c *obfsPacketConn) SetWriteDeadline(t time.Time) error {
+	return c.conn.SetWriteDeadline(t)
+}