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62 lines
1.8 KiB
Go
62 lines
1.8 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package seqnum defines the types and methods for TCP sequence numbers such
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// that they fit in 32-bit words and work properly when overflows occur.
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package seqnum
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// Value represents the value of a sequence number.
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type Value uint32
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// Size represents the size (length) of a sequence number window.
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type Size uint32
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// LessThan checks if v is before w, i.e., v < w.
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func (v Value) LessThan(w Value) bool {
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return int32(v-w) < 0
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}
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// LessThanEq returns true if v==w or v is before i.e., v < w.
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func (v Value) LessThanEq(w Value) bool {
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if v == w {
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return true
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}
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return v.LessThan(w)
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}
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// InRange checks if v is in the range [a,b), i.e., a <= v < b.
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func (v Value) InRange(a, b Value) bool {
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return v-a < b-a
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}
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// InWindow checks if v is in the window that starts at 'first' and spans 'size'
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// sequence numbers.
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func (v Value) InWindow(first Value, size Size) bool {
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return v.InRange(first, first.Add(size))
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}
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// Add calculates the sequence number following the [v, v+s) window.
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func (v Value) Add(s Size) Value {
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return v + Value(s)
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}
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// Size calculates the size of the window defined by [v, w).
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func (v Value) Size(w Value) Size {
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return Size(w - v)
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}
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// UpdateForward updates v such that it becomes v + s.
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func (v *Value) UpdateForward(s Size) {
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*v += Value(s)
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}
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