diff --git a/cmd/netstack/main.go b/cmd/netstack/main.go
index 308835f..882b099 100644
--- a/cmd/netstack/main.go
+++ b/cmd/netstack/main.go
@@ -147,11 +147,12 @@ func main() {
 			go func() {
 				for {
 					buf := make([]byte, 1024)
-					if _, err := conn.Read(buf); err != nil {
+					n, err := conn.Read(buf)
+					if err != nil {
 						log.Println(err)
 						break
 					}
-					fmt.Println("data: ", len(buf), string(buf))
+					fmt.Println("data: ", n, len(buf), string(buf))
 					//	conn.Write([]byte("Server echo"))
 					//}
 				}
@@ -160,16 +161,20 @@ func main() {
 	}()
 
 	<-done
+
 	go func() {
 		port := localPort
 		conn, err := Dial(s, header.IPv4ProtocolNumber, addr, port)
 		if err != nil {
 			log.Fatal(err)
 		}
-		log.Println("客户端 建立连接")
-		buf := make([]byte, 1<<21)
+		log.Printf("客户端 建立连接\n")
+
+		time.Sleep(time.Second)
+		log.Printf("\n\n客户端 写入数据")
+		buf := make([]byte, 1<<17)
 		conn.Write(buf)
-		time.Sleep(3 * time.Second)
+		time.Sleep(1 * time.Minute)
 		conn.Close()
 	}()
 
@@ -237,7 +242,7 @@ func (conn *TcpConn) Read(rcv []byte) (int, error) {
 			n = cap(rcv)
 		}
 		rcv = append(rcv[:0], buf[:n]...)
-		return n, nil
+		return len(buf), nil
 	}
 }
 
diff --git a/tcpip/seqnum/seqnum.go b/tcpip/seqnum/seqnum.go
index 53d33ae..36df6ac 100644
--- a/tcpip/seqnum/seqnum.go
+++ b/tcpip/seqnum/seqnum.go
@@ -21,11 +21,10 @@ func (v Value) LessThanEq(w Value) bool {
 
 // InRange v ∈ [a, b)
 func (v Value) InRange(a, b Value) bool {
-	//return a <= v && v < b
-	return v-a < b-a
+	return v-a < b-a // 注意 uint32(-1) > uint32(0)
 }
 
-// InWindows check v in [first, first+size)
+// InWindow check v in [first, first+size)
 func (v Value) InWindow(first Value, size Size) bool {
 	return v.InRange(first, first.Add(size))
 }
diff --git a/tcpip/transport/tcp/connect.go b/tcpip/transport/tcp/connect.go
index b39209c..bea155f 100644
--- a/tcpip/transport/tcp/connect.go
+++ b/tcpip/transport/tcp/connect.go
@@ -82,10 +82,10 @@ const (
 // 根据这些参数生成 syn+ack 报文的选项参数，附在 tcp 选项中，回复给主机 A。
 func newHandshake(ep *endpoint, rcvWnd seqnum.Size) (handshake, *tcpip.Error) {
 	h := handshake{
-		ep:     ep,
-		active: true,   // 激活这个管理器
-		rcvWnd: rcvWnd, // 初始接收窗口
-		// TODO
+		ep:          ep,
+		active:      true,                 // 激活这个管理器
+		rcvWnd:      rcvWnd,               // 初始接收窗口
+		rcvWndScale: FindWndScale(rcvWnd), // 接收窗口扩展因子
 	}
 	if err := h.resetState(); err != nil {
 		return handshake{}, err
@@ -93,6 +93,25 @@ func newHandshake(ep *endpoint, rcvWnd seqnum.Size) (handshake, *tcpip.Error) {
 	return h, nil
 }
 
+// FindWndScale determines the window scale to use for the given maximum window
+// size.
+// 因为窗口的大小不能超过序列号范围的一半，即窗口最大2^30,
+// so (2^16)*(2^maxWnsScale) < 2^30,get maxWnsScale = 14
+func FindWndScale(wnd seqnum.Size) int {
+	if wnd < 0x10000 {
+		return 0
+	}
+
+	max := seqnum.Size(0xffff)
+	s := 0
+	for wnd > max && s < header.MaxWndScale {
+		s++
+		max <<= 1
+	}
+
+	return s
+}
+
 func (h *handshake) resetState() *tcpip.Error {
 	// 随机一个iss(对方将收到的序号) 防止黑客搞事
 	b := make([]byte, 4)
@@ -301,7 +320,7 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error {
 func (h *handshake) handleSegment(s *segment) *tcpip.Error {
 	h.sndWnd = s.window
 	if !s.flagIsSet(flagSyn) && h.sndWndScale > 0 {
-		h.sndWnd <<= uint8(h.sndWndScale)
+		h.sndWnd <<= uint8(h.sndWndScale) // 收紧窗口
 	}
 
 	switch h.state {
@@ -619,13 +638,13 @@ func (e *endpoint) sendRaw(data buffer.VectorisedView, flags byte, seq, ack seqn
 func (e *endpoint) handleWrite() *tcpip.Error {
 	e.sndBufMu.Lock()
 
-	// 得到第一个tcp段
+	// 得到第一个tcp段 注意并不是取出只是查看
 	first := e.sndQueue.Front()
 	if first != nil {
 		// 向发送链表添加元素
 		e.snd.writeList.PushBackList(&e.sndQueue)
 		// NOTE 更新发送队列下一个发送字节的序号 一次性将链表全部取用
-		// 当有新的数据需要发送时会有相关逻辑更新这个数值
+		// 当有新的数据需要发送时会有相逻辑更新这个数值
 		e.snd.sndNxtList.UpdateForward(e.sndBufInQueue)
 		e.sndBufInQueue = 0
 	}
@@ -684,7 +703,6 @@ func (e *endpoint) handleSegments() *tcpip.Error {
 			// Patch the window size in the segment according to the
 			// send window scale.
 			s.window <<= e.snd.sndWndScale
-
 			// If the timestamp option is negotiated and the segment
 			// does not carry a timestamp option then the segment
 			// must be dropped as per
@@ -713,8 +731,8 @@ func (e *endpoint) handleSegments() *tcpip.Error {
 
 	// tcp可靠性：累积确认
 	// 如果发送的最大ack不等于下一个接收的序列号，发送ack
-	log.Println("============", e.rcv.rcvNxt, e.snd.maxSentAck, "=============")
 	if e.rcv.rcvNxt != e.snd.maxSentAck {
+		fmt.Printf("\n\n=======ACK=======%d=======ACK======\n\n", e.rcv.rcvNxt-e.snd.maxSentAck)
 		e.snd.sendAck()
 	}
 
diff --git a/tcpip/transport/tcp/endpoint.go b/tcpip/transport/tcp/endpoint.go
index 9ba7dd3..7c9b94f 100644
--- a/tcpip/transport/tcp/endpoint.go
+++ b/tcpip/transport/tcp/endpoint.go
@@ -818,6 +818,19 @@ func (e *endpoint) HandleControlPacket(id stack.TransportEndpointID, typ stack.C
 
 }
 
+// 当收到ack确认时 需要更新发送确认缓冲占用
+func (e *endpoint) updateSndBufferUsage(v int) {
+	e.sndBufMu.Lock()
+	notify := e.sndBufUsed >= e.sndBufSize>>1
+	e.sndBufUsed -= v
+	notify = notify && e.sndBufUsed < e.sndBufSize>>1
+	e.sndBufMu.Unlock()
+	if notify { // 如果缓存中剩余的数据过多是不需要补充的
+		log.Fatal("缓存中剩余的数据", e.sndBufUsed, notify)
+		e.waiterQueue.Notify(waiter.EventOut)
+	}
+}
+
 func (e *endpoint) readyToRead(s *segment) {
 	e.rcvListMu.Lock()
 	if s != nil {
@@ -840,14 +853,11 @@ func (e *endpoint) receiveBufferAvailable() int {
 	size := e.rcvBufSize
 	used := e.rcvBufUsed
 	e.rcvListMu.Unlock()
-
 	// We may use more bytes than the buffer size when the receive buffer
 	// shrinks.
 	if used >= size {
 		return 0
 	}
-
-	log.Println("Init Recv Windeow Size: ", size-used)
 	return size - used
 }
 
diff --git a/tcpip/transport/tcp/rcv.go b/tcpip/transport/tcp/rcv.go
index 6e776ac..fdb4134 100644
--- a/tcpip/transport/tcp/rcv.go
+++ b/tcpip/transport/tcp/rcv.go
@@ -58,6 +58,7 @@ func (r *receiver) getSendParams() (rcvNxt seqnum.Value, rcvWnd seqnum.Size) {
 		r.rcvAcc = acc
 	}
 
+	log.Println("-------------", n, acc, r.rcvWndScale)
 	return r.rcvNxt, r.rcvNxt.Size(r.rcvAcc) >> r.rcvWndScale
 }
 
diff --git a/tcpip/transport/tcp/segment.go b/tcpip/transport/tcp/segment.go
index d938b48..a6b718b 100644
--- a/tcpip/transport/tcp/segment.go
+++ b/tcpip/transport/tcp/segment.go
@@ -114,6 +114,20 @@ func (s *segment) incRef() {
 	atomic.AddInt32(&s.refCnt, 1)
 }
 
+// logicalLen is the segment length in the sequence number space. It's defined
+// as the data length plus one for each of the SYN and FIN bits set.
+// 计算tcp段的逻辑长度，包括负载数据的长度，如果有控制标记，需要加1
+func (s *segment) logicalLen() seqnum.Size {
+	l := seqnum.Size(s.data.Size())
+	if s.flagIsSet(flagSyn) {
+		l++
+	}
+	if s.flagIsSet(flagFin) {
+		l++
+	}
+	return l
+}
+
 func (s *segment) parse() bool {
 	h := header.TCP(s.data.First())
 	offset := int(h.DataOffset())
diff --git a/tcpip/transport/tcp/snd.go b/tcpip/transport/tcp/snd.go
index 1c3af44..c6b54c3 100644
--- a/tcpip/transport/tcp/snd.go
+++ b/tcpip/transport/tcp/snd.go
@@ -9,6 +9,7 @@ import (
 	"netstack/tcpip/seqnum"
 	"sync"
 	"time"
+	"unsafe"
 )
 
 const (
@@ -253,6 +254,7 @@ func (s *sender) sendSegment(data buffer.VectorisedView, flags byte, seq seqnum.
 	// Remember the max sent ack.
 	s.maxSentAck = rcvNxt
 
+	log.Println(s.ep.id.LocalPort, "要求扩展窗口", s.sndWnd)
 	return s.ep.sendRaw(data, flags, seq, rcvNxt, rcvWnd)
 }
 
@@ -262,6 +264,62 @@ func (s *sender) handleRcvdSegment(seg *segment) {
 	// 因此发送更多数据。如果需要，这也将重新启用重传计时器。
 	// 存放当前窗口大小。
 	s.sndWnd = seg.window
+	log.Println(s.ep.id.LocalPort, "移动窗口", s.sndWnd)
+	// 获取确认号
+	ack := seg.ackNumber
+	// 如果ack在最小未确认的seq和segNext之间
+	if (ack - 1).InRange(s.sndUna, s.sndNxt) {
+		log.Printf("[...XXXXXX]-[%d|\t%d\t|%d]==>", s.sndNxt, ack-1, s.sndUna)
+		if s.ep.sendTSOk && seg.parsedOptions.TSEcr != 0 {
+			// TSVal/Ecr values sent by Netstack are at a millisecond
+			// granularity.
+			//elapsed := time.Duration(s.ep.timestamp()-seg.parsedOptions.TSEcr) * time.Millisecond
+			//s.updateRTO(elapsed)
+		}
+		// 获取这次确认的字节数，即 ack - snaUna
+		acked := s.sndUna.Size(ack)
+		// 更新下一个未确认的序列号
+		s.sndUna = ack
+
+		ackLeft := acked
+		//originalOutstanding := s.outstanding
+		// 从发送链表中删除已经确认的数据，发送窗口的滑动。
+		//log.Printf("[...XXXXXX]-[%d|\t\t|%d]==>", s.sndNxt, s.sndUna)
+		for ackLeft > 0 { // 有成功确认的数据 丢弃它们 有剩余数据的话继续发送(根据拥塞策略控制)
+			seg := s.writeList.Front()
+			datalen := seg.logicalLen()
+
+			if datalen > ackLeft {
+				seg.data.TrimFront(int(ackLeft))
+				break
+			}
+
+			log.Println(s.writeNext == seg)
+			if s.writeNext == seg {
+				log.Fatal("更新 下一段")
+				s.writeNext = seg.Next()
+			}
+			// 从发送链表中删除已确认的tcp段。
+			s.writeList.Remove(seg)
+			// 因为有一个tcp段确认了，所以 outstanding 减1
+			s.outstanding--
+			seg.decRef()
+			ackLeft -= datalen
+		}
+		// 当收到ack确认时，需要更新发送缓冲占用
+		s.ep.updateSndBufferUsage(int(acked))
+
+		// 如果发生超时重传时，s.outstanding可能会降到零以下，
+		// 重置为零但后来得到一个覆盖先前发送数据的确认。
+		if s.outstanding < 0 {
+			s.outstanding = 0
+		}
+	}
+
+	// TODO tcp拥塞控制
+	if s.writeList.Front() != nil {
+		log.Println("确认成功 继续发送")
+	}
 
 	s.sendData()
 }
@@ -297,6 +355,7 @@ func (s *sender) sendData() {
 				panic("Netstack queues FIN segments without data.")
 			}
 			if !seg.sequenceNumber.LessThan(end) {
+				log.Println("暂停数据发送", seg.sequenceNumber, end)
 				break
 			}
 
@@ -309,18 +368,19 @@ func (s *sender) sendData() {
 			// 如果seg的payload字节数大于available
 			// 将seg进行分段，并且插入到该seg的后面
 			if seg.data.Size() > available {
+				log.Println("-------------------------------------分段！！！", seg.data.Size(), available, end)
 				nSeg := seg.clone()
-				nSeg.data.TrimFront(available)
 				nSeg.sequenceNumber.UpdateForward(seqnum.Size(available))
 				s.writeList.InsertAfter(seg, nSeg)
 				seg.data.CapLength(available)
 			}
 
 			s.outstanding++
-			log.Println("发送窗口一开始是", s.sndWnd,
-				"最多发送数据", available, dataSent,
-				"发送端缓存包数量", s.outstanding)
 			segEnd = seg.sequenceNumber.Add(seqnum.Size(seg.data.Size()))
+			log.Println("发送窗口一开始是", s.sndWnd,
+				"最多发送数据", available,
+				"缓存数据尾", segEnd,
+				"发送端缓存包数量", s.outstanding)
 		}
 
 		if !dataSent { // 上面有个break能跳过这一步
@@ -331,12 +391,18 @@ func (s *sender) sendData() {
 		s.sendSegment(seg.data, seg.flags, seg.sequenceNumber)
 		// 发送一个数据段后，更新sndNxt
 		if s.sndNxt.LessThan(segEnd) {
+			log.Println("更新sndNxt", s.sndNxt, segEnd)
 			s.sndNxt = segEnd
 		}
 	}
-
 	// Remember the next segment we'll write.
 	s.writeNext = seg
+	if seg != nil {
+		log.Println("-------------------------------------分段！！！", s.writeNext.data.Size())
+		log.Println(unsafe.Pointer(seg), seg.data.Size())
+	}
+
+	time.Sleep(200 * time.Millisecond)
 
 	// TODO 启动定时器
 }