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// 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 pipe provides the implementation of pipe-like data-link layer
// endpoints. Such endpoints allow packets to be sent between two interfaces.
package pipe
import (
"sync"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/stack"
)
var _ stack.LinkEndpoint = (*Endpoint)(nil)
// New returns both ends of a new pipe.
func New(linkAddr1, linkAddr2 tcpip.LinkAddress, mtu uint32) (*Endpoint, *Endpoint) {
ep1 := &Endpoint{
linkAddr: linkAddr1,
mtu: mtu,
}
ep2 := &Endpoint{
linkAddr: linkAddr2,
mtu: mtu,
}
ep1.linked = ep2
ep2.linked = ep1
return ep1, ep2
}
// Endpoint is one end of a pipe.
//
// +stateify savable
type Endpoint struct {
linked *Endpoint
mu sync.RWMutex `state:"nosave"`
// +checklocks:mu
dispatcher stack.NetworkDispatcher
// +checklocks:mu
linkAddr tcpip.LinkAddress
// +checklocks:mu
mtu uint32
}
func (e *Endpoint) deliverPackets(pkts stack.PacketBufferList) {
if !e.linked.IsAttached() {
return
}
for _, pkt := range pkts.AsSlice() {
// Create a fresh packet with pkt's payload but without struct fields
// or headers set so the next link protocol can properly set the link
// header.
newPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
Payload: pkt.ToBuffer(),
})
e.linked.mu.RLock()
d := e.linked.dispatcher
e.linked.mu.RUnlock()
d.DeliverNetworkPacket(pkt.NetworkProtocolNumber, newPkt)
newPkt.DecRef()
}
}
// WritePackets implements stack.LinkEndpoint.
func (e *Endpoint) WritePackets(pkts stack.PacketBufferList) (int, tcpip.Error) {
n := pkts.Len()
e.deliverPackets(pkts)
return n, nil
}
// Attach implements stack.LinkEndpoint.
func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
e.mu.Lock()
defer e.mu.Unlock()
e.dispatcher = dispatcher
}
// IsAttached implements stack.LinkEndpoint.
func (e *Endpoint) IsAttached() bool {
e.mu.RLock()
defer e.mu.RUnlock()
return e.dispatcher != nil
}
// Wait implements stack.LinkEndpoint.
func (*Endpoint) Wait() {}
// MTU implements stack.LinkEndpoint.
func (e *Endpoint) MTU() uint32 {
e.mu.RLock()
defer e.mu.RUnlock()
return e.mtu
}
// SetMTU implements stack.LinkEndpoint.
func (e *Endpoint) SetMTU(mtu uint32) {
e.mu.Lock()
defer e.mu.Unlock()
e.mtu = mtu
}
// Capabilities implements stack.LinkEndpoint.
func (*Endpoint) Capabilities() stack.LinkEndpointCapabilities {
return 0
}
// MaxHeaderLength implements stack.LinkEndpoint.
func (*Endpoint) MaxHeaderLength() uint16 {
return 0
}
// LinkAddress implements stack.LinkEndpoint.
func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
e.mu.RLock()
defer e.mu.RUnlock()
return e.linkAddr
}
// SetLinkAddress implements stack.LinkEndpoint.
func (e *Endpoint) SetLinkAddress(addr tcpip.LinkAddress) {
e.mu.Lock()
defer e.mu.Unlock()
e.linkAddr = addr
}
// ARPHardwareType implements stack.LinkEndpoint.
func (*Endpoint) ARPHardwareType() header.ARPHardwareType {
return header.ARPHardwareNone
}
// AddHeader implements stack.LinkEndpoint.
func (*Endpoint) AddHeader(*stack.PacketBuffer) {}
// ParseHeader implements stack.LinkEndpoint.
func (*Endpoint) ParseHeader(*stack.PacketBuffer) bool { return true }
// Close implements stack.LinkEndpoint.
func (e *Endpoint) Close() {}
// SetOnCloseAction implements stack.LinkEndpoint.SetOnCloseAction.
func (*Endpoint) SetOnCloseAction(func()) {}
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