解析tcp segment 报文与tcp配置

tcpip/transport/tcp/segment.go

@@ -4,11 +4,46 @@ import (
 	"log"
 	"netstack/tcpip/buffer"
 	"netstack/tcpip/header"
+	"netstack/tcpip/seqnum"
 	"netstack/tcpip/stack"
+	"strings"
 	"sync/atomic"
 )
 
-// tcp 太复杂了 专门写一个协议解析器
+// tcp 太复杂了 专门写一个协议解析器 segment 是有种类之分的
+
+// Flags that may be set in a TCP segment.
+const (
+	flagFin = 1 << iota
+	flagSyn
+	flagRst
+	flagPsh
+	flagAck
+	flagUrg
+)
+
+func flagString(flags uint8) string {
+	var s []string
+	if (flags & flagAck) != 0 {
+		s = append(s, "ack")
+	}
+	if (flags & flagFin) != 0 {
+		s = append(s, "fin")
+	}
+	if (flags & flagPsh) != 0 {
+		s = append(s, "psh")
+	}
+	if (flags & flagRst) != 0 {
+		s = append(s, "rst")
+	}
+	if (flags & flagSyn) != 0 {
+		s = append(s, "syn")
+	}
+	if (flags & flagUrg) != 0 {
+		s = append(s, "urg")
+	}
+	return strings.Join(s, "|")
+}
 
 // segment 表示一个 TCP 段。它保存有效负载和解析的 TCP 段信息，并且可以添加到侵入列表中
 type segment struct {
@@ -20,7 +55,15 @@ type segment struct {
 	// views is used as buffer for data when its length is large
 	// enough to store a VectorisedView.
 	views [8]buffer.View
-	// TODO 需要添加
+	// TODO 需要解析
+	viewToDeliver  int
+	sequenceNumber seqnum.Value // tcp序号 第一个字节在整个报文的位置
+	ackNumber      seqnum.Value // 确认号 希望继续获取的下一个字节序号
+	flags          uint8
+	window         seqnum.Size
+	// parsedOptions stores the parsed values from the options in the segment.
+	parsedOptions header.TCPOptions
+	options       []byte
 }
 
 func newSegment(r *stack.Route, id stack.TransportEndpointID, vv buffer.VectorisedView) *segment {
@@ -41,5 +84,18 @@ func (s *segment) incRef() {
 
 func (s *segment) parse() bool {
 	log.Println(header.TCP(s.data.First()))
-	return false
+	h := header.TCP(s.data.First())
+	offset := int(h.DataOffset())
+	if offset < header.TCPMinimumSize || offset > len(h) {
+		return false
+	}
+	s.options = h.Options()
+	//s.parsedOptions = header.ParseTCPOptions(s.options)
+	s.data.TrimFront(offset)
+
+	s.sequenceNumber = seqnum.Value(h.SequenceNumber())
+	s.ackNumber = seqnum.Value(h.AckNumber())
+	s.flags = h.Flags() // U|A|P|R|S|F
+	s.window = seqnum.Size(h.WindowSize())
+	return true
 }