github.com/google/netstack@v0.0.0-20191123085552-55fcc16cd0eb/tcpip/transport/icmp/protocol.go (about)

     1  // Copyright 2018 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 icmp contains the implementation of the ICMP and IPv6-ICMP transport
    16  // protocols for use in ping. To use it in the networking stack, this package
    17  // must be added to the project, and activated on the stack by passing
    18  // icmp.NewProtocol4() and/or icmp.NewProtocol6() as one of the transport
    19  // protocols when calling stack.New(). Then endpoints can be created by passing
    20  // icmp.ProtocolNumber or icmp.ProtocolNumber6 as the transport protocol number
    21  // when calling Stack.NewEndpoint().
    22  package icmp
    23  
    24  import (
    25  	"fmt"
    26  
    27  	"github.com/google/netstack/tcpip"
    28  	"github.com/google/netstack/tcpip/buffer"
    29  	"github.com/google/netstack/tcpip/header"
    30  	"github.com/google/netstack/tcpip/stack"
    31  	"github.com/google/netstack/tcpip/transport/raw"
    32  	"github.com/google/netstack/waiter"
    33  )
    34  
    35  const (
    36  	// ProtocolNumber4 is the ICMP protocol number.
    37  	ProtocolNumber4 = header.ICMPv4ProtocolNumber
    38  
    39  	// ProtocolNumber6 is the IPv6-ICMP protocol number.
    40  	ProtocolNumber6 = header.ICMPv6ProtocolNumber
    41  )
    42  
    43  // protocol implements stack.TransportProtocol.
    44  type protocol struct {
    45  	number tcpip.TransportProtocolNumber
    46  }
    47  
    48  // Number returns the ICMP protocol number.
    49  func (p *protocol) Number() tcpip.TransportProtocolNumber {
    50  	return p.number
    51  }
    52  
    53  func (p *protocol) netProto() tcpip.NetworkProtocolNumber {
    54  	switch p.number {
    55  	case ProtocolNumber4:
    56  		return header.IPv4ProtocolNumber
    57  	case ProtocolNumber6:
    58  		return header.IPv6ProtocolNumber
    59  	}
    60  	panic(fmt.Sprint("unknown protocol number: ", p.number))
    61  }
    62  
    63  // NewEndpoint creates a new icmp endpoint. It implements
    64  // stack.TransportProtocol.NewEndpoint.
    65  func (p *protocol) NewEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
    66  	if netProto != p.netProto() {
    67  		return nil, tcpip.ErrUnknownProtocol
    68  	}
    69  	return newEndpoint(stack, netProto, p.number, waiterQueue)
    70  }
    71  
    72  // NewRawEndpoint creates a new raw icmp endpoint. It implements
    73  // stack.TransportProtocol.NewRawEndpoint.
    74  func (p *protocol) NewRawEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
    75  	if netProto != p.netProto() {
    76  		return nil, tcpip.ErrUnknownProtocol
    77  	}
    78  	return raw.NewEndpoint(stack, netProto, p.number, waiterQueue)
    79  }
    80  
    81  // MinimumPacketSize returns the minimum valid icmp packet size.
    82  func (p *protocol) MinimumPacketSize() int {
    83  	switch p.number {
    84  	case ProtocolNumber4:
    85  		return header.ICMPv4MinimumSize
    86  	case ProtocolNumber6:
    87  		return header.ICMPv6MinimumSize
    88  	}
    89  	panic(fmt.Sprint("unknown protocol number: ", p.number))
    90  }
    91  
    92  // ParsePorts in case of ICMP sets src to 0, dst to ICMP ID, and err to nil.
    93  func (p *protocol) ParsePorts(v buffer.View) (src, dst uint16, err *tcpip.Error) {
    94  	switch p.number {
    95  	case ProtocolNumber4:
    96  		hdr := header.ICMPv4(v)
    97  		return 0, hdr.Ident(), nil
    98  	case ProtocolNumber6:
    99  		hdr := header.ICMPv6(v)
   100  		return 0, hdr.Ident(), nil
   101  	}
   102  	panic(fmt.Sprint("unknown protocol number: ", p.number))
   103  }
   104  
   105  // HandleUnknownDestinationPacket handles packets targeted at this protocol but
   106  // that don't match any existing endpoint.
   107  func (p *protocol) HandleUnknownDestinationPacket(*stack.Route, stack.TransportEndpointID, tcpip.PacketBuffer) bool {
   108  	return true
   109  }
   110  
   111  // SetOption implements TransportProtocol.SetOption.
   112  func (p *protocol) SetOption(option interface{}) *tcpip.Error {
   113  	return tcpip.ErrUnknownProtocolOption
   114  }
   115  
   116  // Option implements TransportProtocol.Option.
   117  func (p *protocol) Option(option interface{}) *tcpip.Error {
   118  	return tcpip.ErrUnknownProtocolOption
   119  }
   120  
   121  // NewProtocol4 returns an ICMPv4 transport protocol.
   122  func NewProtocol4() stack.TransportProtocol {
   123  	return &protocol{ProtocolNumber4}
   124  }
   125  
   126  // NewProtocol6 returns an ICMPv6 transport protocol.
   127  func NewProtocol6() stack.TransportProtocol {
   128  	return &protocol{ProtocolNumber6}
   129  }