github.com/noisysockets/netstack@v0.6.0/pkg/tcpip/link/pipe/pipe.go (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package pipe provides the implementation of pipe-like data-link layer
    16  // endpoints. Such endpoints allow packets to be sent between two interfaces.
    17  package pipe
    18  
    19  import (
    20  	"sync"
    21  
    22  	"github.com/noisysockets/netstack/pkg/tcpip"
    23  	"github.com/noisysockets/netstack/pkg/tcpip/header"
    24  	"github.com/noisysockets/netstack/pkg/tcpip/stack"
    25  )
    26  
    27  var _ stack.LinkEndpoint = (*Endpoint)(nil)
    28  
    29  // New returns both ends of a new pipe.
    30  func New(linkAddr1, linkAddr2 tcpip.LinkAddress, mtu uint32) (*Endpoint, *Endpoint) {
    31  	ep1 := &Endpoint{
    32  		linkAddr: linkAddr1,
    33  		mtu:      mtu,
    34  	}
    35  	ep2 := &Endpoint{
    36  		linkAddr: linkAddr2,
    37  		mtu:      mtu,
    38  	}
    39  	ep1.linked = ep2
    40  	ep2.linked = ep1
    41  	return ep1, ep2
    42  }
    43  
    44  // Endpoint is one end of a pipe.
    45  type Endpoint struct {
    46  	linked   *Endpoint
    47  	linkAddr tcpip.LinkAddress
    48  	mtu      uint32
    49  
    50  	mu sync.RWMutex
    51  	// +checklocks:mu
    52  	dispatcher stack.NetworkDispatcher
    53  }
    54  
    55  func (e *Endpoint) deliverPackets(pkts stack.PacketBufferList) {
    56  	if !e.linked.IsAttached() {
    57  		return
    58  	}
    59  
    60  	for _, pkt := range pkts.AsSlice() {
    61  		// Create a fresh packet with pkt's payload but without struct fields
    62  		// or headers set so the next link protocol can properly set the link
    63  		// header.
    64  		newPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
    65  			Payload: pkt.ToBuffer(),
    66  		})
    67  		e.linked.mu.RLock()
    68  		d := e.linked.dispatcher
    69  		e.linked.mu.RUnlock()
    70  		d.DeliverNetworkPacket(pkt.NetworkProtocolNumber, newPkt)
    71  		newPkt.DecRef()
    72  	}
    73  }
    74  
    75  // WritePackets implements stack.LinkEndpoint.
    76  func (e *Endpoint) WritePackets(pkts stack.PacketBufferList) (int, tcpip.Error) {
    77  	n := pkts.Len()
    78  	e.deliverPackets(pkts)
    79  	return n, nil
    80  }
    81  
    82  // Attach implements stack.LinkEndpoint.
    83  func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
    84  	e.mu.Lock()
    85  	defer e.mu.Unlock()
    86  	e.dispatcher = dispatcher
    87  }
    88  
    89  // IsAttached implements stack.LinkEndpoint.
    90  func (e *Endpoint) IsAttached() bool {
    91  	e.mu.RLock()
    92  	defer e.mu.RUnlock()
    93  	return e.dispatcher != nil
    94  }
    95  
    96  // Wait implements stack.LinkEndpoint.
    97  func (*Endpoint) Wait() {}
    98  
    99  // MTU implements stack.LinkEndpoint.
   100  func (e *Endpoint) MTU() uint32 {
   101  	return e.mtu
   102  }
   103  
   104  // Capabilities implements stack.LinkEndpoint.
   105  func (*Endpoint) Capabilities() stack.LinkEndpointCapabilities {
   106  	return 0
   107  }
   108  
   109  // MaxHeaderLength implements stack.LinkEndpoint.
   110  func (*Endpoint) MaxHeaderLength() uint16 {
   111  	return 0
   112  }
   113  
   114  // LinkAddress implements stack.LinkEndpoint.
   115  func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
   116  	return e.linkAddr
   117  }
   118  
   119  // ARPHardwareType implements stack.LinkEndpoint.
   120  func (*Endpoint) ARPHardwareType() header.ARPHardwareType {
   121  	return header.ARPHardwareNone
   122  }
   123  
   124  // AddHeader implements stack.LinkEndpoint.
   125  func (*Endpoint) AddHeader(*stack.PacketBuffer) {}
   126  
   127  // ParseHeader implements stack.LinkEndpoint.
   128  func (*Endpoint) ParseHeader(*stack.PacketBuffer) bool { return true }