mirror of
https://github.com/impact-eintr/netstack.git
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73 lines
2.2 KiB
Go
73 lines
2.2 KiB
Go
package loopback
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import (
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"fmt"
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"netstack/logger"
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"netstack/tcpip"
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"netstack/tcpip/buffer"
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"netstack/tcpip/stack"
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)
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type endpoint struct {
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count int
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dispatcher stack.NetworkDispatcher
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}
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func New() tcpip.LinkEndpointID {
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return stack.RegisterLinkEndpoint(&endpoint{})
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}
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func (e *endpoint) MTU() uint32 {
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return 65536
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}
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// Capabilities返回链路层端点支持的功能集。
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func (e *endpoint) Capabilities() stack.LinkEndpointCapabilities {
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return stack.CapabilityChecksumOffload | stack.CapabilitySaveRestore | stack.CapabilityLoopback
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}
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// MaxHeaderLength 返回数据链接（和较低级别的图层组合）标头可以具有的最大大小。
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// 较高级别使用此信息来保留它们正在构建的数据包前面预留空间。
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func (e *endpoint) MaxHeaderLength() uint16 {
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return 0
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}
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// 本地链路层地址
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func (e *endpoint) LinkAddress() tcpip.LinkAddress {
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return ""
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}
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// 要参与透明桥接，LinkEndpoint实现应调用eth.Encode，
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// 并将header.EthernetFields.SrcAddr设置为r.LocalLinkAddress（如果已提供）。
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func (e *endpoint) WritePacket(r *stack.Route, hdr buffer.Prependable, payload buffer.VectorisedView,
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protocol tcpip.NetworkProtocolNumber) *tcpip.Error {
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views := make([]buffer.View, 1, 1+len(payload.Views()))
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views[0] = hdr.View()
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views = append(views, payload.Views()...)
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vv := buffer.NewVectorisedView(len(views[0])+payload.Size(), views)
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// TODO 这里整点活 在特定的情况下丢掉数据报 模拟网络阻塞
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e.count++
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if e.count == 5 || e.count == 7 || e.count == 9 {
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logger.NOTICE(fmt.Sprintf("统计 %d 丢掉这个报文", e.count))
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return nil
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}
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// Because we're immediately turning around and writing the packet back to the
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// rx path, we intentionally don't preserve the remote and local link
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// addresses from the stack.Route we're passed.
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e.dispatcher.DeliverNetworkPacket(e, "" /* remoteLinkAddr */, "" /* localLinkAddr */, protocol, vv)
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return nil
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}
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// Attach 将数据链路层端点附加到协议栈的网络层调度程序。
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func (e *endpoint) Attach(dispatcher stack.NetworkDispatcher) {
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e.dispatcher = dispatcher
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}
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// 是否已经添加了网络层调度器
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func (e *endpoint) IsAttached() bool {
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return e.dispatcher != nil
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}
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