68 lines
1.6 KiB
Go
68 lines
1.6 KiB
Go
// Copyright 2016 The Netstack Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package fragmentation
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import (
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"container/heap"
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"fmt"
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"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
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)
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type fragment struct {
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offset uint16
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vv *buffer.VectorisedView
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}
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type fragHeap []fragment
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func (h *fragHeap) Len() int {
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return len(*h)
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}
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func (h *fragHeap) Less(i, j int) bool {
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return (*h)[i].offset < (*h)[j].offset
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}
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func (h *fragHeap) Swap(i, j int) {
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(*h)[i], (*h)[j] = (*h)[j], (*h)[i]
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}
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func (h *fragHeap) Push(x interface{}) {
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*h = append(*h, x.(fragment))
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}
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func (h *fragHeap) Pop() interface{} {
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old := *h
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n := len(old)
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x := old[n-1]
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*h = old[:n-1]
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return x
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}
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// reassamble empties the heap and returns a VectorisedView
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// containing a reassambled version of the fragments inside the heap.
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func (h *fragHeap) reassemble() (buffer.VectorisedView, error) {
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curr := heap.Pop(h).(fragment)
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views := curr.vv.Views()
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size := curr.vv.Size()
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if curr.offset != 0 {
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return buffer.NewVectorisedView(0, nil), fmt.Errorf("offset of the first packet is != 0 (%d)", curr.offset)
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}
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for h.Len() > 0 {
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curr := heap.Pop(h).(fragment)
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if int(curr.offset) < size {
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curr.vv.TrimFront(size - int(curr.offset))
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} else if int(curr.offset) > size {
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return buffer.NewVectorisedView(0, nil), fmt.Errorf("packet has a hole, expected offset %d, got %d", size, curr.offset)
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}
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size += curr.vv.Size()
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views = append(views, curr.vv.Views()...)
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}
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return buffer.NewVectorisedView(size, views), nil
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}
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