Better detector

Author: Fangliding

fingerprint_detect.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"strconv"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/pires/go-proxyproto"
@@ -145,19 +146,44 @@ type CCSDetectConn struct {
 
 func (c *CCSDetectConn) Write(b []byte) (n int, err error) {
 	if len(b) >= 3 && bytes.Equal(b[:3], []byte{20, 3, 3}) {
-		var i int
-		// 32(idx 31) → max allowed (what's we need)
-		// 33(idx 32) → trigger remote TLS Alert
-		// 34(idx 33) → trigger remote TCP RST
-		// 35(idx 34) → write err, pass to system
-		for i = range 35 {
-			if _, err = c.Conn.Write(CCSMsg); err != nil {
-				break
-			} else {
-				time.Sleep(c.rtt * 2)
+		var hasAlert atomic.Bool
+		go func() {
+			defer hasAlert.Store(true)
+			buf := make([]byte, 512)
+			for {
+				_, err = c.Conn.Read(buf)
+				if err != nil {
+					return
+				}
+				if buf[0] == 0x15 {
+					return
+				}
 			}
+		}()
+		sendProbePayload := func(count int) bool {
+			msg := bytes.Repeat(CCSMsg, count)
+			rtt := max(100*time.Millisecond, c.rtt)
+			c.Conn.Write(msg)
+			time.Sleep(rtt)
+			if hasAlert.Load() {
+				return true
+			}
+			return false
+		}
+		if sendProbePayload(2) {
+			GlobalMaxCSSMsgCount.Store(c.Key, 1)
+			return c.Conn.Write(b)
+		}
+		if sendProbePayload(15) {
+			GlobalMaxCSSMsgCount.Store(c.Key, 16)
+			return c.Conn.Write(b)
+		}
+		if sendProbePayload(16) {
+			GlobalMaxCSSMsgCount.Store(c.Key, 32)
+			return c.Conn.Write(b)
 		}
-		GlobalMaxCSSMsgCount.Store(c.Key, i-2)
+		GlobalMaxCSSMsgCount.Store(c.Key, 1145141919810)
+		return c.Conn.Write(b)
 	}
 	return c.Conn.Write(b)
 }