Add TLS fragment support

common/tlsfragment/conn.go

@@ -0,0 +1,107 @@
+package tf
+
+import (
+	"context"
+	"math/rand"
+	"net"
+	"strings"
+	"time"
+
+	N "github.com/sagernet/sing/common/network"
+
+	"golang.org/x/net/publicsuffix"
+)
+
+type Conn struct {
+	net.Conn
+	tcpConn            *net.TCPConn
+	ctx                context.Context
+	firstPacketWritten bool
+	fallbackDelay      time.Duration
+}
+
+func NewConn(conn net.Conn, ctx context.Context, fallbackDelay time.Duration) (*Conn, error) {
+	tcpConn, _ := N.UnwrapReader(conn).(*net.TCPConn)
+	return &Conn{
+		Conn:          conn,
+		tcpConn:       tcpConn,
+		ctx:           ctx,
+		fallbackDelay: fallbackDelay,
+	}, nil
+}
+
+func (c *Conn) Write(b []byte) (n int, err error) {
+	if !c.firstPacketWritten {
+		defer func() {
+			c.firstPacketWritten = true
+		}()
+		serverName := indexTLSServerName(b)
+		if serverName != nil {
+			if c.tcpConn != nil {
+				err = c.tcpConn.SetNoDelay(true)
+				if err != nil {
+					return
+				}
+			}
+			splits := strings.Split(serverName.ServerName, ".")
+			currentIndex := serverName.Index
+			if publicSuffix := publicsuffix.List.PublicSuffix(serverName.ServerName); publicSuffix != "" {
+				splits = splits[:len(splits)-strings.Count(serverName.ServerName, ".")]
+			}
+			if len(splits) > 1 && splits[0] == "..." {
+				currentIndex += len(splits[0]) + 1
+				splits = splits[1:]
+			}
+			var splitIndexes []int
+			for i, split := range splits {
+				splitAt := rand.Intn(len(split))
+				splitIndexes = append(splitIndexes, currentIndex+splitAt)
+				currentIndex += len(split)
+				if i != len(splits)-1 {
+					currentIndex++
+				}
+			}
+			for i := 0; i <= len(splitIndexes); i++ {
+				var payload []byte
+				if i == 0 {
+					payload = b[:splitIndexes[i]]
+				} else if i == len(splitIndexes) {
+					payload = b[splitIndexes[i-1]:]
+				} else {
+					payload = b[splitIndexes[i-1]:splitIndexes[i]]
+				}
+				if c.tcpConn != nil && i != len(splitIndexes) {
+					err = writeAndWaitAck(c.ctx, c.tcpConn, payload, c.fallbackDelay)
+					if err != nil {
+						return
+					}
+				} else {
+					_, err = c.Conn.Write(payload)
+					if err != nil {
+						return
+					}
+				}
+			}
+			if c.tcpConn != nil {
+				err = c.tcpConn.SetNoDelay(false)
+				if err != nil {
+					return
+				}
+			}
+			return len(b), nil
+		}
+	}
+	return c.Conn.Write(b)
+}
+
+func (c *Conn) ReaderReplaceable() bool {
+	return true
+}
+
+func (c *Conn) WriterReplaceable() bool {
+	return c.firstPacketWritten
+}
+
+func (c *Conn) Upstream() any {
+	return c.Conn
+}