147 lines
4.5 KiB
Go
147 lines
4.5 KiB
Go
// Copyright 2020 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 nested provides helpers to implement the pattern of nested
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// stack.LinkEndpoints.
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package nested
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import (
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"gvisor.dev/gvisor/pkg/sync"
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"gvisor.dev/gvisor/pkg/tcpip"
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"gvisor.dev/gvisor/pkg/tcpip/header"
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"gvisor.dev/gvisor/pkg/tcpip/stack"
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)
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// Endpoint is a wrapper around stack.LinkEndpoint and stack.NetworkDispatcher
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// that can be used to implement nesting safely by providing lifecycle
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// concurrency guards.
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//
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// See the tests in this package for example usage.
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type Endpoint struct {
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child stack.LinkEndpoint
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embedder stack.NetworkDispatcher
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// mu protects dispatcher.
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mu sync.RWMutex
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dispatcher stack.NetworkDispatcher
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}
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var _ stack.GSOEndpoint = (*Endpoint)(nil)
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var _ stack.LinkEndpoint = (*Endpoint)(nil)
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var _ stack.NetworkDispatcher = (*Endpoint)(nil)
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// Init initializes a nested.Endpoint that uses embedder as the dispatcher for
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// child on Attach.
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//
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// See the tests in this package for example usage.
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func (e *Endpoint) Init(child stack.LinkEndpoint, embedder stack.NetworkDispatcher) {
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e.child = child
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e.embedder = embedder
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}
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// DeliverNetworkPacket implements stack.NetworkDispatcher.
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func (e *Endpoint) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
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e.mu.RLock()
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d := e.dispatcher
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e.mu.RUnlock()
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if d != nil {
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d.DeliverNetworkPacket(remote, local, protocol, pkt)
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}
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}
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// DeliverOutboundPacket implements stack.NetworkDispatcher.DeliverOutboundPacket.
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func (e *Endpoint) DeliverOutboundPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
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e.mu.RLock()
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d := e.dispatcher
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e.mu.RUnlock()
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if d != nil {
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d.DeliverOutboundPacket(remote, local, protocol, pkt)
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}
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}
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// Attach implements stack.LinkEndpoint.
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func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
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e.mu.Lock()
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e.dispatcher = dispatcher
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e.mu.Unlock()
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// If we're attaching to a valid dispatcher, pass embedder as the dispatcher
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// to our child, otherwise detach the child by giving it a nil dispatcher.
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var pass stack.NetworkDispatcher
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if dispatcher != nil {
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pass = e.embedder
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}
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e.child.Attach(pass)
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}
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// IsAttached implements stack.LinkEndpoint.
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func (e *Endpoint) IsAttached() bool {
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e.mu.RLock()
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isAttached := e.dispatcher != nil
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e.mu.RUnlock()
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return isAttached
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}
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// MTU implements stack.LinkEndpoint.
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func (e *Endpoint) MTU() uint32 {
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return e.child.MTU()
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}
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// Capabilities implements stack.LinkEndpoint.
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func (e *Endpoint) Capabilities() stack.LinkEndpointCapabilities {
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return e.child.Capabilities()
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}
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// MaxHeaderLength implements stack.LinkEndpoint.
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func (e *Endpoint) MaxHeaderLength() uint16 {
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return e.child.MaxHeaderLength()
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}
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// LinkAddress implements stack.LinkEndpoint.
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func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
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return e.child.LinkAddress()
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}
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// WritePacket implements stack.LinkEndpoint.
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func (e *Endpoint) WritePacket(r stack.RouteInfo, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
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return e.child.WritePacket(r, gso, protocol, pkt)
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}
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// WritePackets implements stack.LinkEndpoint.
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func (e *Endpoint) WritePackets(r stack.RouteInfo, gso *stack.GSO, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
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return e.child.WritePackets(r, gso, pkts, protocol)
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}
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// Wait implements stack.LinkEndpoint.
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func (e *Endpoint) Wait() {
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e.child.Wait()
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}
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// GSOMaxSize implements stack.GSOEndpoint.
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func (e *Endpoint) GSOMaxSize() uint32 {
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if e, ok := e.child.(stack.GSOEndpoint); ok {
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return e.GSOMaxSize()
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}
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return 0
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}
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// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType
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func (e *Endpoint) ARPHardwareType() header.ARPHardwareType {
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return e.child.ARPHardwareType()
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}
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// AddHeader implements stack.LinkEndpoint.AddHeader.
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func (e *Endpoint) AddHeader(local, remote tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) {
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e.child.AddHeader(local, remote, protocol, pkt)
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}
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