138 lines
3.8 KiB
Go
138 lines
3.8 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 channel provides the implemention of channel-based data-link layer
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// endpoints. Such endpoints allow injection of inbound packets and store
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// outbound packets in a channel.
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package channel
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import (
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"gvisor.dev/gvisor/pkg/tcpip"
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"gvisor.dev/gvisor/pkg/tcpip/buffer"
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"gvisor.dev/gvisor/pkg/tcpip/stack"
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)
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// PacketInfo holds all the information about an outbound packet.
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type PacketInfo struct {
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Header buffer.View
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Payload buffer.View
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Proto tcpip.NetworkProtocolNumber
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GSO *stack.GSO
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}
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// Endpoint is link layer endpoint that stores outbound packets in a channel
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// and allows injection of inbound packets.
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type Endpoint struct {
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dispatcher stack.NetworkDispatcher
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mtu uint32
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linkAddr tcpip.LinkAddress
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GSO bool
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// C is where outbound packets are queued.
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C chan PacketInfo
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}
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// New creates a new channel endpoint.
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func New(size int, mtu uint32, linkAddr tcpip.LinkAddress) (tcpip.LinkEndpointID, *Endpoint) {
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e := &Endpoint{
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C: make(chan PacketInfo, size),
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mtu: mtu,
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linkAddr: linkAddr,
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}
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return stack.RegisterLinkEndpoint(e), e
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}
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// Drain removes all outbound packets from the channel and counts them.
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func (e *Endpoint) Drain() int {
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c := 0
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for {
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select {
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case <-e.C:
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c++
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default:
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return c
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}
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}
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}
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// Inject injects an inbound packet.
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func (e *Endpoint) Inject(protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
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e.InjectLinkAddr(protocol, "", vv)
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}
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// InjectLinkAddr injects an inbound packet with a remote link address.
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func (e *Endpoint) InjectLinkAddr(protocol tcpip.NetworkProtocolNumber, remote tcpip.LinkAddress, vv buffer.VectorisedView) {
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e.dispatcher.DeliverNetworkPacket(e, remote, "" /* local */, protocol, vv.Clone(nil))
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}
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// Attach saves the stack network-layer dispatcher for use later when packets
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// are injected.
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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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// IsAttached implements stack.LinkEndpoint.IsAttached.
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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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// MTU implements stack.LinkEndpoint.MTU. It returns the value initialized
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// during construction.
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func (e *Endpoint) MTU() uint32 {
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return e.mtu
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}
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// Capabilities implements stack.LinkEndpoint.Capabilities.
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func (e *Endpoint) Capabilities() stack.LinkEndpointCapabilities {
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caps := stack.LinkEndpointCapabilities(0)
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if e.GSO {
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caps |= stack.CapabilityGSO
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}
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return caps
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}
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// GSOMaxSize returns the maximum GSO packet size.
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func (*Endpoint) GSOMaxSize() uint32 {
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return 1 << 15
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}
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// MaxHeaderLength returns the maximum size of the link layer header. Given it
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// doesn't have a header, it just returns 0.
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func (*Endpoint) MaxHeaderLength() uint16 {
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return 0
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}
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// LinkAddress returns the link address of this endpoint.
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func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
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return e.linkAddr
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}
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// WritePacket stores outbound packets into the channel.
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func (e *Endpoint) WritePacket(_ *stack.Route, gso *stack.GSO, hdr buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.NetworkProtocolNumber) *tcpip.Error {
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p := PacketInfo{
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Header: hdr.View(),
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Proto: protocol,
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Payload: payload.ToView(),
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GSO: gso,
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}
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select {
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case e.C <- p:
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default:
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}
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return nil
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}
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