tcp报文头结构可视化解析;优化IP udp报文的可视化解析

tcpip/seqnum/seqnum.go

@@ -0,0 +1,50 @@
+package seqnum
+
+// Value represents the value of a sequence number.
+type Value uint32
+
+// Size represents the size (length) of a sequence number window
+type Size uint32
+
+// LessThan v < w
+func (v Value) LessThan(w Value) bool {
+	return int32(v-w) < 0
+}
+
+// LessThanEq returns true if v==w or v is before i.e., v < w.
+func (v Value) LessThanEq(w Value) bool {
+	if v == w {
+		return true
+	}
+	return v.LessThan(w)
+}
+
+// InRange v ∈ [a, b)
+func (v Value) InRange(a, b Value) bool {
+	return a <= v && v < b
+}
+
+// InWindows check v in [first, first+size)
+func (v Value) InWindows(first Value, size Size) bool {
+	return v.InRange(first, first.Add(size))
+}
+
+// Add return v + s
+func (v Value) Add(s Size) Value {
+	return v + Value(s)
+}
+
+// Size return the size of [v, w)
+func (v Value) Size(w Value) Size {
+	return Size(w - v)
+}
+
+// UpdateForward update the value to v+s
+func (v *Value) UpdateForward(s Size) {
+	*v += Value(s)
+}
+
+// Overlap checks if the window [a,a+b) overlaps with the window [x, x+y).
+func Overlap(a Value, b Size, x Value, y Size) bool {
+	return a.LessThan(x.Add(y)) && x.LessThan(a.Add(b))
+}