From 94e12c1f213eb9a105c7e1794344d07bd8f00c65 Mon Sep 17 00:00:00 2001
From: impact-eintr <yixingwei4@gmail.com>
Date: Wed, 21 Dec 2022 17:46:16 +0800
Subject: [PATCH] =?UTF-8?q?RTT=20=E8=BF=98=E6=98=AF=E6=B2=A1=E6=95=B4?=
 =?UTF-8?q?=E6=98=8E=E7=99=BD?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 tcpip/link/loopback/loopback.go |  4 ++++
 tcpip/transport/tcp/accept.go   |  5 +----
 tcpip/transport/tcp/connect.go  |  2 --
 tcpip/transport/tcp/endpoint.go | 10 ++++++++++
 tcpip/transport/tcp/rcv.go      |  7 +++----
 tcpip/transport/tcp/snd.go      | 16 ++++++++++++----
 6 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/tcpip/link/loopback/loopback.go b/tcpip/link/loopback/loopback.go
index e98a4e3..8f7b463 100644
--- a/tcpip/link/loopback/loopback.go
+++ b/tcpip/link/loopback/loopback.go
@@ -2,10 +2,12 @@ package loopback
 
 import (
 	"fmt"
+	"math/rand"
 	"netstack/logger"
 	"netstack/tcpip"
 	"netstack/tcpip/buffer"
 	"netstack/tcpip/stack"
+	"time"
 )
 
 type endpoint struct {
@@ -47,6 +49,8 @@ func (e *endpoint) WritePacket(r *stack.Route, hdr buffer.Prependable, payload b
 	vv := buffer.NewVectorisedView(len(views[0])+payload.Size(), views)
 
 	// TODO 这里整点活 在特定的情况下丢掉数据报 模拟网络阻塞
+	rand.Seed(time.Now().Unix())
+	//time.Sleep(time.Duration(rand.Intn(50)+50) * time.Millisecond)
 
 	e.count++
 	if e.count == -1 { // 丢掉客户端写入的第二个包
diff --git a/tcpip/transport/tcp/accept.go b/tcpip/transport/tcp/accept.go
index 9c46a1b..b6e5148 100644
--- a/tcpip/transport/tcp/accept.go
+++ b/tcpip/transport/tcp/accept.go
@@ -251,11 +251,8 @@ func (l *listenContext) createEndpointAndPerformHandshake(s *segment, opts *head
 		return nil, err
 	}
 
-	// TODO 更新接收窗口扩张因子
+	// 更新接收窗口扩张因子
 	ep.rcv.rcvWndScale = h.effectiveRcvWndScale()
-	logger.GetInstance().Info(logger.HANDSHAKE, func() {
-		log.Println("ep.rcv.rcvWndScale", ep.rcv.rcvWndScale)
-	})
 
 	return ep, nil
 }
diff --git a/tcpip/transport/tcp/connect.go b/tcpip/transport/tcp/connect.go
index 3534cb9..6642d4d 100644
--- a/tcpip/transport/tcp/connect.go
+++ b/tcpip/transport/tcp/connect.go
@@ -712,8 +712,6 @@ func (e *endpoint) handleClose() *tcpip.Error {
 // handleSegments 从队列中取出 tcp 段数据，然后处理它们。
 func (e *endpoint) handleSegments() *tcpip.Error {
 	checkRequeue := true
-	// FIXME 用于更清楚地DUBUG 之后删掉
-	time.Sleep(100 * time.Millisecond)
 
 	for i := 0; i < maxSegmentsPerWake; i++ {
 		s := e.segmentQueue.dequeue()
diff --git a/tcpip/transport/tcp/endpoint.go b/tcpip/transport/tcp/endpoint.go
index 74ef553..dfb87a1 100644
--- a/tcpip/transport/tcp/endpoint.go
+++ b/tcpip/transport/tcp/endpoint.go
@@ -130,6 +130,8 @@ type endpoint struct {
 	// recentTS is the timestamp that should be sent in the TSEcr field of
 	// the timestamp for future segments sent by the endpoint. This field is
 	// updated if required when a new segment is received by this endpoint.
+	// recentTS 是应该在端点发送的未来段的时间戳的 TSEcr 字段中发送的时间戳。
+	// 当此端点接收到新段时，如果需要，此字段会更新。
 	recentTS uint32
 
 	// tsOffset is a randomized offset added to the value of the
@@ -1173,6 +1175,14 @@ func (e *endpoint) receiveBufferSize() int {
 	return size
 }
 
+// updateRecentTimestamp updates the recent timestamp using the algorithm
+// described in https://tools.ietf.org/html/rfc7323#section-4.3
+func (e *endpoint) updateRecentTimestamp(tsVal uint32, maxSentAck seqnum.Value, segSeq    seqnum.Value) {
+	if e.sendTSOk && seqnum.Value(e.recentTS).LessThan(seqnum.Value(tsVal)) && segSeq.      LessThanEq(maxSentAck) {
+		e.recentTS = tsVal
+	}
+}
+
 // maybeEnableTimestamp marks the timestamp option enabled for this endpoint if
 // the SYN options indicate that timestamp option was negotiated. It also
 // initializes the recentTS with the value provided in synOpts.TSval.
diff --git a/tcpip/transport/tcp/rcv.go b/tcpip/transport/tcp/rcv.go
index 8488f1c..b2203f2 100644
--- a/tcpip/transport/tcp/rcv.go
+++ b/tcpip/transport/tcp/rcv.go
@@ -3,7 +3,6 @@ package tcp
 import (
 	"container/heap"
 	"fmt"
-	"log"
 	"netstack/logger"
 	"netstack/tcpip/seqnum"
 )
@@ -100,9 +99,9 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum
 	logger.GetInstance().Info(logger.TCP, func() {
 	})
 
-	if r.ep.id.LocalPort == 9999 {
-		log.Println(r)
-	}
+	//if r.ep.id.LocalPort == 9999 {
+	//	log.Println(r)
+	//}
 
 	// 修剪SACK块以删除任何涵盖已消耗序列号的SACK信息。
 	TrimSACKBlockList(&r.ep.sack, r.rcvNxt)
diff --git a/tcpip/transport/tcp/snd.go b/tcpip/transport/tcp/snd.go
index da10a9e..7146d60 100644
--- a/tcpip/transport/tcp/snd.go
+++ b/tcpip/transport/tcp/snd.go
@@ -203,6 +203,7 @@ func newSender(ep *endpoint, iss, irs seqnum.Value, sndWnd seqnum.Size, mss uint
 		sndNxt:         iss + 1, // 缓存长度为0
 		sndNxtList:     iss + 1,
 		rto:            1 * time.Second,
+		rttMeasureSeqNum: iss + 1,
 		lastSendTime:   time.Now(),
 		maxPayloadSize: int(mss),
 		maxSentAck:     irs + 1,
@@ -377,7 +378,7 @@ func (s *sender) resendSegment() {
 // sequence number.
 // 根据给定的参数，负载数据、flags标记和序列号来发送数据
 func (s *sender) sendSegment(data buffer.VectorisedView, flags byte, seq seqnum.Value) *tcpip.Error {
-	s.lastSendTime = time.Now()
+	s.lastSendTime = time.Now() // 发送时间
 	if seq == s.rttMeasureSeqNum {
 		s.rttMeasureTime = s.lastSendTime
 	}
@@ -398,6 +399,8 @@ func (s *sender) handleRcvdSegment(seg *segment) {
 		s.rttMeasureSeqNum = s.sndNxt
 	}
 
+	s.ep.updateRecentTimestamp(seg.parsedOptions.TSVal, s.maxSentAck, seg.sequenceNumber)
+
 	// tcp的拥塞控制：检查是否有重复的ack，是否进入快速重传和快速恢复状态
 	rtx := s.checkDuplicateAck(seg)
 
@@ -405,12 +408,16 @@ func (s *sender) handleRcvdSegment(seg *segment) {
 	s.sndWnd = seg.window
 	// 获取确认号
 	ack := seg.ackNumber
+	if s.ep.id.LocalPort != 9999 {
+		logger.NOTICE("进入处理ack报文", atoi(ack-1), atoi(s.sndUna), atoi(s.sndNxt))
+	}
 	// 如果ack在最小未确认的seq和segNext之间
 	if (ack - 1).InRange(s.sndUna, s.sndNxt) {
 		// 收到了东西 就暂停计时
 		s.resendTimer.disable()
 
 		// NOTE 一个RTT 结束
+		logger.NOTICE(time.Duration(seg.parsedOptions.TSEcr).String())
 		if s.ep.sendTSOk && seg.parsedOptions.TSEcr != 0 {
 			// TSVal/Ecr values sent by Netstack are at a millisecond
 			// granularity.
@@ -467,9 +474,9 @@ func (s *sender) handleRcvdSegment(seg *segment) {
 		s.resendSegment()
 	}
 
-	if s.ep.id.LocalPort != 9999 {
-		log.Println(s)
-	}
+	//if s.ep.id.LocalPort != 9999 {
+	//	log.Println(s)
+	//}
 
 	// 现在某些待处理数据已被确认，或者窗口打开，或者由于快速恢复期间出现重复的ack而导致拥塞窗口膨胀，
 	// 因此发送更多数据。如果需要，这也将重新启用重传计时器。
@@ -577,6 +584,7 @@ func (s *sender) sendData() {
 			// TODO
 		}
 
+		// 发送包 开始计算RTT
 		s.sendSegment(seg.data, seg.flags, seg.sequenceNumber)
 		// 发送一个数据段后，更新sndNxt
 		if s.sndNxt.LessThan(segEnd) {