icmp

package
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 Go to latest Published: Jan 10, 2024 License: BSD-3-Clause Imports: 13 Imported by: 0

Documentation

Overview

Package icmp provides basic functions for the manipulation of messages used in the Internet Control Message Protocols, ICMPv4 and ICMPv6.

ICMPv4 and ICMPv6 are defined in RFC 792 and RFC 4443. Multi-part message support for ICMP is defined in RFC 4884. ICMP extensions for MPLS are defined in RFC 4950. ICMP extensions for interface and next-hop identification are defined in RFC 5837. PROBE: A utility for probing interfaces is defined in RFC 8335.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func IPv6PseudoHeader 

func IPv6PseudoHeader(src, dst net.IP) []byte

IPv6PseudoHeader returns an IPv6 pseudo header for checksum calculation.

func ParseIPv4Header 

func ParseIPv4Header(b []byte) (*ipv4.Header, error)

ParseIPv4Header returns the IPv4 header of the IPv4 packet that triggered an ICMP error message. This is found in the Data field of the ICMP error message body.

The provided b must be in the format used by a raw ICMP socket on the local system. This may differ from the wire format, and the format used by a raw IP socket, depending on the system.

To parse an IPv6 header, use ipv6.ParseHeader.

Types

type DefaultMessageBody deprecated 

type DefaultMessageBody = RawBody

A DefaultMessageBody represents the default message body.

Deprecated: Use RawBody instead.

type DstUnreach 

type DstUnreach struct {
	Data       []byte      // data, known as original datagram field
	Extensions []Extension // extensions
}

A DstUnreach represents an ICMP destination unreachable message body.

func (*DstUnreach) Len 

func (p *DstUnreach) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*DstUnreach) Marshal 

func (p *DstUnreach) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type Echo 

type Echo struct {
	ID   int    // identifier
	Seq  int    // sequence number
	Data []byte // data
}

An Echo represents an ICMP echo request or reply message body.

func (*Echo) Len 

func (p *Echo) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*Echo) Marshal 

func (p *Echo) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type ExtendedEchoReply 

type ExtendedEchoReply struct {
	ID     int  // identifier
	Seq    int  // sequence number
	State  int  // 3-bit state working together with Message.Code
	Active bool // probed interface is active
	IPv4   bool // probed interface runs IPv4
	IPv6   bool // probed interface runs IPv6
}

An ExtendedEchoReply represents an ICMP extended echo reply message body.

func (*ExtendedEchoReply) Len 

func (p *ExtendedEchoReply) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*ExtendedEchoReply) Marshal 

func (p *ExtendedEchoReply) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type ExtendedEchoRequest 

type ExtendedEchoRequest struct {
	ID         int         // identifier
	Seq        int         // sequence number
	Local      bool        // must be true when identifying by name or index
	Extensions []Extension // extensions
}

An ExtendedEchoRequest represents an ICMP extended echo request message body.

func (*ExtendedEchoRequest) Len 

func (p *ExtendedEchoRequest) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*ExtendedEchoRequest) Marshal 

func (p *ExtendedEchoRequest) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type Extension 

type Extension interface {
	// Len returns the length of ICMP extension.
	// The provided proto must be either the ICMPv4 or ICMPv6
	// protocol number.
	Len(proto int) int

	// Marshal returns the binary encoding of ICMP extension.
	// The provided proto must be either the ICMPv4 or ICMPv6
	// protocol number.
	Marshal(proto int) ([]byte, error)
}

An Extension represents an ICMP extension.

type InterfaceIdent 

type InterfaceIdent struct {
	Class int    // extension object class number
	Type  int    // extension object sub-type
	Name  string // interface name
	Index int    // interface index
	AFI   int    // address family identifier; see address family numbers in IANA registry
	Addr  []byte // address
}

An InterfaceIdent represents interface identification.

func (*InterfaceIdent) Len 

func (ifi *InterfaceIdent) Len(_ int) int

Len implements the Len method of Extension interface.

func (*InterfaceIdent) Marshal 

func (ifi *InterfaceIdent) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of Extension interface.

type InterfaceInfo 

type InterfaceInfo struct {
	Class     int // extension object class number
	Type      int // extension object sub-type
	Interface *net.Interface
	Addr      *net.IPAddr
}

An InterfaceInfo represents interface and next-hop identification.

func (*InterfaceInfo) Len 

func (ifi *InterfaceInfo) Len(proto int) int

Len implements the Len method of Extension interface.

func (*InterfaceInfo) Marshal 

func (ifi *InterfaceInfo) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of Extension interface.

type MPLSLabel 

type MPLSLabel struct {
	Label int  // label value
	TC    int  // traffic class; formerly experimental use
	S     bool // bottom of stack
	TTL   int  // time to live
}

MPLSLabel represents an MPLS label stack entry.

type MPLSLabelStack 

type MPLSLabelStack struct {
	Class  int // extension object class number
	Type   int // extension object sub-type
	Labels []MPLSLabel
}

MPLSLabelStack represents an MPLS label stack.

func (*MPLSLabelStack) Len 

func (ls *MPLSLabelStack) Len(proto int) int

Len implements the Len method of Extension interface.

func (*MPLSLabelStack) Marshal 

func (ls *MPLSLabelStack) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of Extension interface.

type Message 

type Message struct {
	Type     Type        // type, either ipv4.ICMPType or ipv6.ICMPType
	Code     int         // code
	Checksum int         // checksum
	Body     MessageBody // body
}

A Message represents an ICMP message.

func ParseMessage 

func ParseMessage(proto int, b []byte) (*Message, error)

ParseMessage parses b as an ICMP message. The provided proto must be either the ICMPv4 or ICMPv6 protocol number.

func (*Message) Marshal 

func (m *Message) Marshal(psh []byte) ([]byte, error)

Marshal returns the binary encoding of the ICMP message m.

For an ICMPv4 message, the returned message always contains the calculated checksum field.

For an ICMPv6 message, the returned message contains the calculated checksum field when psh is not nil, otherwise the kernel will compute the checksum field during the message transmission. When psh is not nil, it must be the pseudo header for IPv6.

type MessageBody 

type MessageBody interface {
	// Len returns the length of ICMP message body.
	// The provided proto must be either the ICMPv4 or ICMPv6
	// protocol number.
	Len(proto int) int

	// Marshal returns the binary encoding of ICMP message body.
	// The provided proto must be either the ICMPv4 or ICMPv6
	// protocol number.
	Marshal(proto int) ([]byte, error)
}

A MessageBody represents an ICMP message body.

type PacketConn 

type PacketConn struct {
	// contains filtered or unexported fields
}

A PacketConn represents a packet network endpoint that uses either ICMPv4 or ICMPv6.

Example (NonPrivilegedPing) 
package main

import (
	"log"
	"net"
	"os"
	"runtime"

	"golang.org/x/net/icmp"
	"golang.org/x/net/ipv6"
)

func main() {
	switch runtime.GOOS {
	case "darwin", "ios":
	case "linux":
		log.Println("you may need to adjust the net.ipv4.ping_group_range kernel state")
	default:
		log.Println("not supported on", runtime.GOOS)
		return
	}

	c, err := icmp.ListenPacket("udp6", "fe80::1%en0")
	if err != nil {
		log.Fatal(err)
	}
	defer c.Close()

	wm := icmp.Message{
		Type: ipv6.ICMPTypeEchoRequest, Code: 0,
		Body: &icmp.Echo{
			ID: os.Getpid() & 0xffff, Seq: 1,
			Data: []byte("HELLO-R-U-THERE"),
		},
	}
	wb, err := wm.Marshal(nil)
	if err != nil {
		log.Fatal(err)
	}
	if _, err := c.WriteTo(wb, &net.UDPAddr{IP: net.ParseIP("ff02::1"), Zone: "en0"}); err != nil {
		log.Fatal(err)
	}

	rb := make([]byte, 1500)
	n, peer, err := c.ReadFrom(rb)
	if err != nil {
		log.Fatal(err)
	}
	rm, err := icmp.ParseMessage(58, rb[:n])
	if err != nil {
		log.Fatal(err)
	}
	switch rm.Type {
	case ipv6.ICMPTypeEchoReply:
		log.Printf("got reflection from %v", peer)
	default:
		log.Printf("got %+v; want echo reply", rm)
	}
}

Output:

func ListenPacket 

func ListenPacket(network, address string) (*PacketConn, error)

ListenPacket listens for incoming ICMP packets addressed to address. See net.Dial for the syntax of address.

For non-privileged datagram-oriented ICMP endpoints, network must be "udp4" or "udp6". The endpoint allows to read, write a few limited ICMP messages such as echo request and echo reply. Currently only Darwin and Linux support this.

Examples: 

ListenPacket("udp4", "192.168.0.1")
ListenPacket("udp4", "0.0.0.0")
ListenPacket("udp6", "fe80::1%en0")
ListenPacket("udp6", "::")

For privileged raw ICMP endpoints, network must be "ip4" or "ip6" followed by a colon and an ICMP protocol number or name.

Examples: 

ListenPacket("ip4:icmp", "192.168.0.1")
ListenPacket("ip4:1", "0.0.0.0")
ListenPacket("ip6:ipv6-icmp", "fe80::1%en0")
ListenPacket("ip6:58", "::")

func (*PacketConn) Close 

func (c *PacketConn) Close() error

Close closes the endpoint.

func (*PacketConn) IPv4PacketConn 

func (c *PacketConn) IPv4PacketConn() *ipv4.PacketConn

IPv4PacketConn returns the ipv4.PacketConn of c. It returns nil when c is not created as the endpoint for ICMPv4.

func (*PacketConn) IPv6PacketConn 

func (c *PacketConn) IPv6PacketConn() *ipv6.PacketConn

IPv6PacketConn returns the ipv6.PacketConn of c. It returns nil when c is not created as the endpoint for ICMPv6.

func (*PacketConn) LocalAddr 

func (c *PacketConn) LocalAddr() net.Addr

LocalAddr returns the local network address.

func (*PacketConn) ReadFrom 

func (c *PacketConn) ReadFrom(b []byte) (int, net.Addr, error)

ReadFrom reads an ICMP message from the connection.

func (*PacketConn) SetDeadline 

func (c *PacketConn) SetDeadline(t time.Time) error

SetDeadline sets the read and write deadlines associated with the endpoint.

func (*PacketConn) SetReadDeadline 

func (c *PacketConn) SetReadDeadline(t time.Time) error

SetReadDeadline sets the read deadline associated with the endpoint.

func (*PacketConn) SetWriteDeadline 

func (c *PacketConn) SetWriteDeadline(t time.Time) error

SetWriteDeadline sets the write deadline associated with the endpoint.

func (*PacketConn) WriteTo 

func (c *PacketConn) WriteTo(b []byte, dst net.Addr) (int, error)

WriteTo writes the ICMP message b to dst. The provided dst must be net.UDPAddr when c is a non-privileged datagram-oriented ICMP endpoint. Otherwise it must be net.IPAddr.

type PacketTooBig 

type PacketTooBig struct {
	MTU  int    // maximum transmission unit of the nexthop link
	Data []byte // data, known as original datagram field
}

A PacketTooBig represents an ICMP packet too big message body.

func (*PacketTooBig) Len 

func (p *PacketTooBig) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*PacketTooBig) Marshal 

func (p *PacketTooBig) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type ParamProb 

type ParamProb struct {
	Pointer    uintptr     // offset within the data where the error was detected
	Data       []byte      // data, known as original datagram field
	Extensions []Extension // extensions
}

A ParamProb represents an ICMP parameter problem message body.

func (*ParamProb) Len 

func (p *ParamProb) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*ParamProb) Marshal 

func (p *ParamProb) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type RawBody 

type RawBody struct {
	Data []byte // data
}

A RawBody represents a raw message body.

A raw message body is excluded from message processing and can be used to construct applications such as protocol conformance testing.

func (*RawBody) Len 

func (p *RawBody) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*RawBody) Marshal 

func (p *RawBody) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type RawExtension 

type RawExtension struct {
	Data []byte // data
}

A RawExtension represents a raw extension.

A raw extension is excluded from message processing and can be used to construct applications such as protocol conformance testing.

func (*RawExtension) Len 

func (p *RawExtension) Len(proto int) int

Len implements the Len method of Extension interface.

func (*RawExtension) Marshal 

func (p *RawExtension) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of Extension interface.

type TimeExceeded 

type TimeExceeded struct {
	Data       []byte      // data, known as original datagram field
	Extensions []Extension // extensions
}

A TimeExceeded represents an ICMP time exceeded message body.

func (*TimeExceeded) Len 

func (p *TimeExceeded) Len(proto int) int

Len implements the Len method of MessageBody interface.

func (*TimeExceeded) Marshal 

func (p *TimeExceeded) Marshal(proto int) ([]byte, error)

Marshal implements the Marshal method of MessageBody interface.

type Type 

type Type interface {
	Protocol() int
}

A Type represents an ICMP message type.

Notes

Bugs

  • This package is not implemented on JS, NaCl and Plan 9.

Source Files

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