Fix: if http proxy Upgrade failure

common/net/relay.go

@@ -12,19 +12,28 @@ import (
 func Relay(leftConn, rightConn net.Conn) {
 	ch := make(chan error)
 
+	tcpKeepAlive(leftConn)
+	tcpKeepAlive(rightConn)
+
 	go func() {
 		buf := pool.Get(pool.RelayBufferSize)
 		// Wrapping to avoid using *net.TCPConn.(ReadFrom)
 		// See also https://github.com/Dreamacro/clash/pull/1209
 		_, err := io.CopyBuffer(WriteOnlyWriter{Writer: leftConn}, ReadOnlyReader{Reader: rightConn}, buf)
-		pool.Put(buf)
-		leftConn.SetReadDeadline(time.Now())
+		_ = pool.Put(buf)
+		_ = leftConn.SetReadDeadline(time.Now())
 		ch <- err
 	}()
 
 	buf := pool.Get(pool.RelayBufferSize)
-	io.CopyBuffer(WriteOnlyWriter{Writer: rightConn}, ReadOnlyReader{Reader: leftConn}, buf)
-	pool.Put(buf)
-	rightConn.SetReadDeadline(time.Now())
+	_, _ = io.CopyBuffer(WriteOnlyWriter{Writer: rightConn}, ReadOnlyReader{Reader: leftConn}, buf)
+	_ = pool.Put(buf)
+	_ = rightConn.SetReadDeadline(time.Now())
 	<-ch
 }
+
+func tcpKeepAlive(c net.Conn) {
+	if tcp, ok := c.(*net.TCPConn); ok {
+		_ = tcp.SetKeepAlive(true)
+	}
+}