Finalmask: Add header-custom (TCP & UDP), fragment (TCP), noise (UDP); Support dialer-proxy, XHTTP/3; Fix XDNS, XICMP potential panic (#5657)

https://github.com/XTLS/Xray-core/pull/5657#issuecomment-4016609446

transport/internet/finalmask/fragment/conn.go

@@ -0,0 +1,128 @@
+package fragment
+
+import (
+	"net"
+	"time"
+
+	"github.com/xtls/xray-core/common/crypto"
+)
+
+type fragmentConn struct {
+	net.Conn
+	config *Config
+	count  uint64
+
+	server bool
+}
+
+func NewConnClient(c *Config, raw net.Conn, server bool) (net.Conn, error) {
+	conn := &fragmentConn{
+		Conn:   raw,
+		config: c,
+
+		server: server,
+	}
+
+	return conn, nil
+}
+
+func NewConnServer(c *Config, raw net.Conn, server bool) (net.Conn, error) {
+	return NewConnClient(c, raw, server)
+}
+
+func (c *fragmentConn) TcpMaskConn() {}
+
+func (c *fragmentConn) RawConn() net.Conn {
+	if c.server {
+		return c
+	}
+	return c.Conn
+}
+
+func (c *fragmentConn) Splice() bool {
+	if c.server {
+		return false
+	}
+	return true
+}
+
+func (c *fragmentConn) Write(p []byte) (n int, err error) {
+	c.count++
+
+	if c.config.PacketsFrom == 0 && c.config.PacketsTo == 1 {
+		if c.count != 1 || len(p) <= 5 || p[0] != 22 {
+			return c.Conn.Write(p)
+		}
+		recordLen := 5 + ((int(p[3]) << 8) | int(p[4]))
+		if len(p) < recordLen {
+			return c.Conn.Write(p)
+		}
+		data := p[5:recordLen]
+		buff := make([]byte, 2048)
+		var hello []byte
+		maxSplit := crypto.RandBetween(c.config.MaxSplitMin, c.config.MaxSplitMax)
+		var splitNum int64
+		for from := 0; ; {
+			to := from + int(crypto.RandBetween(c.config.LengthMin, c.config.LengthMax))
+			splitNum++
+			if to > len(data) || (maxSplit > 0 && splitNum >= maxSplit) {
+				to = len(data)
+			}
+			l := to - from
+			if 5+l > len(buff) {
+				buff = make([]byte, 5+l)
+			}
+			copy(buff[:3], p)
+			copy(buff[5:], data[from:to])
+			from = to
+			buff[3] = byte(l >> 8)
+			buff[4] = byte(l)
+			if c.config.DelayMax == 0 {
+				hello = append(hello, buff[:5+l]...)
+			} else {
+				_, err := c.Conn.Write(buff[:5+l])
+				time.Sleep(time.Duration(crypto.RandBetween(c.config.DelayMin, c.config.DelayMax)) * time.Millisecond)
+				if err != nil {
+					return 0, err
+				}
+			}
+			if from == len(data) {
+				if len(hello) > 0 {
+					_, err := c.Conn.Write(hello)
+					if err != nil {
+						return 0, err
+					}
+				}
+				if len(p) > recordLen {
+					n, err := c.Conn.Write(p[recordLen:])
+					if err != nil {
+						return recordLen + n, err
+					}
+				}
+				return len(p), nil
+			}
+		}
+	}
+
+	if c.config.PacketsFrom != 0 && (c.count < uint64(c.config.PacketsFrom) || c.count > uint64(c.config.PacketsTo)) {
+		return c.Conn.Write(p)
+	}
+	maxSplit := crypto.RandBetween(c.config.MaxSplitMin, c.config.MaxSplitMax)
+	var splitNum int64
+	for from := 0; ; {
+		to := from + int(crypto.RandBetween(c.config.LengthMin, c.config.LengthMax))
+		splitNum++
+		if to > len(p) || (maxSplit > 0 && splitNum >= maxSplit) {
+			to = len(p)
+		}
+		n, err := c.Conn.Write(p[from:to])
+		from += n
+		if err != nil {
+			return from, err
+		}
+		time.Sleep(time.Duration(crypto.RandBetween(c.config.DelayMin, c.config.DelayMax)) * time.Millisecond)
+		if from >= len(p) {
+			return from, nil
+		}
+	}
+}