| // Copyright 2020 The gVisor Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| // Package nested provides helpers to implement the pattern of nested |
| // stack.LinkEndpoints. |
| package nested |
| |
| import ( |
| "gvisor.dev/gvisor/pkg/sync" |
| "gvisor.dev/gvisor/pkg/tcpip" |
| "gvisor.dev/gvisor/pkg/tcpip/header" |
| "gvisor.dev/gvisor/pkg/tcpip/stack" |
| ) |
| |
| // Endpoint is a wrapper around stack.LinkEndpoint and stack.NetworkDispatcher |
| // that can be used to implement nesting safely by providing lifecycle |
| // concurrency guards. |
| // |
| // See the tests in this package for example usage. |
| type Endpoint struct { |
| child stack.LinkEndpoint |
| embedder stack.NetworkDispatcher |
| |
| // mu protects dispatcher. |
| mu sync.RWMutex |
| dispatcher stack.NetworkDispatcher |
| } |
| |
| var _ stack.GSOEndpoint = (*Endpoint)(nil) |
| var _ stack.LinkEndpoint = (*Endpoint)(nil) |
| var _ stack.NetworkDispatcher = (*Endpoint)(nil) |
| |
| // Init initializes a nested.Endpoint that uses embedder as the dispatcher for |
| // child on Attach. |
| // |
| // See the tests in this package for example usage. |
| func (e *Endpoint) Init(child stack.LinkEndpoint, embedder stack.NetworkDispatcher) { |
| e.child = child |
| e.embedder = embedder |
| } |
| |
| // DeliverNetworkPacket implements stack.NetworkDispatcher. |
| func (e *Endpoint) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) { |
| e.mu.RLock() |
| d := e.dispatcher |
| e.mu.RUnlock() |
| if d != nil { |
| d.DeliverNetworkPacket(remote, local, protocol, pkt) |
| } |
| } |
| |
| // DeliverOutboundPacket implements stack.NetworkDispatcher.DeliverOutboundPacket. |
| func (e *Endpoint) DeliverOutboundPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) { |
| e.mu.RLock() |
| d := e.dispatcher |
| e.mu.RUnlock() |
| if d != nil { |
| d.DeliverOutboundPacket(remote, local, protocol, pkt) |
| } |
| } |
| |
| // Attach implements stack.LinkEndpoint. |
| func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) { |
| e.mu.Lock() |
| e.dispatcher = dispatcher |
| e.mu.Unlock() |
| // If we're attaching to a valid dispatcher, pass embedder as the dispatcher |
| // to our child, otherwise detach the child by giving it a nil dispatcher. |
| var pass stack.NetworkDispatcher |
| if dispatcher != nil { |
| pass = e.embedder |
| } |
| e.child.Attach(pass) |
| } |
| |
| // IsAttached implements stack.LinkEndpoint. |
| func (e *Endpoint) IsAttached() bool { |
| e.mu.RLock() |
| isAttached := e.dispatcher != nil |
| e.mu.RUnlock() |
| return isAttached |
| } |
| |
| // MTU implements stack.LinkEndpoint. |
| func (e *Endpoint) MTU() uint32 { |
| return e.child.MTU() |
| } |
| |
| // Capabilities implements stack.LinkEndpoint. |
| func (e *Endpoint) Capabilities() stack.LinkEndpointCapabilities { |
| return e.child.Capabilities() |
| } |
| |
| // MaxHeaderLength implements stack.LinkEndpoint. |
| func (e *Endpoint) MaxHeaderLength() uint16 { |
| return e.child.MaxHeaderLength() |
| } |
| |
| // LinkAddress implements stack.LinkEndpoint. |
| func (e *Endpoint) LinkAddress() tcpip.LinkAddress { |
| return e.child.LinkAddress() |
| } |
| |
| // WritePacket implements stack.LinkEndpoint. |
| func (e *Endpoint) WritePacket(r stack.RouteInfo, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error { |
| return e.child.WritePacket(r, gso, protocol, pkt) |
| } |
| |
| // WritePackets implements stack.LinkEndpoint. |
| func (e *Endpoint) WritePackets(r stack.RouteInfo, gso *stack.GSO, pkts stack.PacketBufferList, protocol tcpip.NetworkProtocolNumber) (int, tcpip.Error) { |
| return e.child.WritePackets(r, gso, pkts, protocol) |
| } |
| |
| // Wait implements stack.LinkEndpoint. |
| func (e *Endpoint) Wait() { |
| e.child.Wait() |
| } |
| |
| // GSOMaxSize implements stack.GSOEndpoint. |
| func (e *Endpoint) GSOMaxSize() uint32 { |
| if e, ok := e.child.(stack.GSOEndpoint); ok { |
| return e.GSOMaxSize() |
| } |
| return 0 |
| } |
| |
| // ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType |
| func (e *Endpoint) ARPHardwareType() header.ARPHardwareType { |
| return e.child.ARPHardwareType() |
| } |
| |
| // AddHeader implements stack.LinkEndpoint.AddHeader. |
| func (e *Endpoint) AddHeader(local, remote tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) { |
| e.child.AddHeader(local, remote, protocol, pkt) |
| } |