dhcp4client

package module
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 Go to latest Published: Feb 28, 2024 License: MPL-2.0 Imports: 15 Imported by: 0

README

dhcp4client GoDoc

DHCP Client

Thanks to:

@eyakubovich For AF_PACKET support.

Documentation

Index

Examples

Constants

View Source 
const (
	//The Maximum size of a DHCP4 response. Used to initialise read buffers.
	MaxDHCPLen = 576
)

Variables

This section is empty.

Functions

func Connection 

func Connection(co connections.Transport) func(*Client) error

Connection is a function option that allows you to configure which connection(s) type to utilise.

func CryptoGenerateXID 

func CryptoGenerateXID(b []byte)

func GenerateXID 

func GenerateXID(g func([]byte)) func(*Client) error

GenerateXID is a function option that allows you to set the function responsible for producing a random XID.

func HardwareAddr 

func HardwareAddr(h net.HardwareAddr) func(*Client) error

HardwareAddr is a function option to set the Hardware(MAC) address of the client.

func IgnoreServers 

func IgnoreServers(s []net.IP) func(*Client) error

IgnoreServers is a function option that allow you to pass an array s of IP's which the client will ignore when the DHCP Server respond with a dhcp4.OptionServerIdentifier (Code 54) in this IP array.

func MathGenerateXID 

func MathGenerateXID(b []byte)

func NewInetSock 

func NewInetSock() (connections.Transport, error)

func NewPacketSock 

func NewPacketSock(ifindex int) (connections.Transport, error)

func Timeout 

func Timeout(t time.Duration) func(*Client) error

Timout is a functional options that lets you set all network timeouts on the client.

Types

type Client 

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

The Main DHCP Control Client

Example

Basic usage example of using the client to complete a DHCP4 request and getting the allocated IP. 

package main

import (
	"fmt"
	"net"

	"github.com/zukadong/dhcp4client"
)

func main() {
	var err error

	m, err := net.ParseMAC("E4-B3-18-64-DC-14")
	if err != nil {
		fmt.Printf("Error: Error Parsing MAC Address:%v\n", err)
		return
	}

	//Create a connection to use
	exampleClient, err := dhcp4client.New(dhcp4client.HardwareAddr(m))
	if err != nil {
		fmt.Printf("Error: Error Creating Client:%v\n", err)
		return
	}
	defer exampleClient.Close()

	//Complete a full DHCP4 Cycle, Discover, Request, Offer, Acknowledgement.
	success, acknowledgementpacket, err := exampleClient.Request()

	if err != nil {
		networkError, ok := err.(net.Error)
		if ok && networkError.Timeout() {
			fmt.Printf("Warning: Didn't get a valid respose from a DHCP server in time.")
			return
		}
		fmt.Printf("Error: Network error when making request %v\n", err)
		return
	}

	if !success {
		fmt.Printf("Warning: We didn't sucessfully get a DHCP Lease")
	} else {
		fmt.Printf("IP address received which can be found in acknowledgementpacket.YIAddr()")

		//Print our IP to stderr as the basic example will get any IP so we can't
		//included it in the tested output.
		fmt.Errorf("Info: IP Received:%s\n", acknowledgementpacket.YIAddr())
	}

}

Output:

IP address received which can be found in acknowledgementpacket.YIAddr()

func New 

func New(options ...func(*Client) error) (*Client, error)

Creates a DHCP4Client instance using functional options to configure settings. More information about function options [https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis]

func (*Client) BroadcastPacket 

func (c *Client) BroadcastPacket(packet dhcp4.Packet) (i int, err error)

BroadcastPacket Allows you to Broadcast the DHCP4 packets over the UDP Connection.

func (*Client) Close 

func (c *Client) Close() error

Close function closes the Client.

func (*Client) DeclinePacket 

func (c *Client) DeclinePacket(acknowledgement *dhcp4.Packet) dhcp4.Packet

Create Decline Packet

func (*Client) DiscoverPacket 

func (c *Client) DiscoverPacket() dhcp4.Packet

Create Discover Packet

func (*Client) GetAcknowledgement 

func (c *Client) GetAcknowledgement(requestPacket *dhcp4.Packet) (dhcp4.Packet, error)

Retrieve Acknowledgement Wait for the offer for a specific Request Packet.

func (*Client) GetAcknowledgementWithOptions 

func (c *Client) GetAcknowledgementWithOptions(requestPacket *dhcp4.Packet, opts DHCP4ClientOptions) (dhcp4.Packet, error)

func (*Client) GetOffer 

func (c *Client) GetOffer(discoverPacket *dhcp4.Packet) (dhcp4.Packet, error)

Retreive Offer... Wait for the offer for a specific Discovery Packet. UDP address contain content of option 54.

func (*Client) GetOfferWithOptions 

func (c *Client) GetOfferWithOptions(xid []byte, opts DHCP4ClientOptions) (dhcp4.Packet, error)

func (*Client) Release 

func (c *Client) Release(dhcpaddr net.UDPAddr, acknowledgement dhcp4.Packet) error

Release a lease backed on the Acknowledgement Packet. Returns Any Errors

func (*Client) ReleasePacket 

func (c *Client) ReleasePacket(acknowledgement *dhcp4.Packet) dhcp4.Packet

Create Release Packet For a Release

func (*Client) Renew 

func (c *Client) Renew(dhcpaddr net.UDPAddr, acknowledgement dhcp4.Packet) (bool, dhcp4.Packet, error)

Renew a lease backed on the Acknowledgement Packet. Returns Sucessfull, The AcknoledgementPacket, Any Errors BUG(d2g): Which directly contradicts [RFC 2131 p28] BUG(d2g): ACK packet doesn't have to contain the server identifier. https://tools.ietf.org/html/rfc2132#section-9.7

func (*Client) RenewalRequestPacket 

func (c *Client) RenewalRequestPacket(l net.IP, s net.IP) dhcp4.Packet

func (*Client) RenewalRequestPacketFromAcknowledgment 

func (c *Client) RenewalRequestPacketFromAcknowledgment(a *dhcp4.Packet) dhcp4.Packet

RenewalRequestPacket Generates Create Request Packet For a Renew

func (*Client) RenewalRequestPacketWithOptions 

func (c *Client) RenewalRequestPacketWithOptions(l net.IP, s net.IP, opts DHCP4ClientOptions) dhcp4.Packet

func (*Client) Request 

func (c *Client) Request() (bool, dhcp4.Packet, error)

Lets do a Full DHCP Request. The Returned UDP Address is the content of Option 54 of the Offer packet. TODO:

func (*Client) RequestPacket 

func (c *Client) RequestPacket(r net.IP, s net.IP) dhcp4.Packet

Create Request Packet r is the IP to request, s is server to request it from

func (*Client) RequestPacketFromOfferPacket 

func (c *Client) RequestPacketFromOfferPacket(offerPacket *dhcp4.Packet) dhcp4.Packet

func (*Client) RequestPacketWithOptions 

func (c *Client) RequestPacketWithOptions(r net.IP, s net.IP, opts DHCP4ClientOptions) dhcp4.Packet

func (*Client) RequestWithOptions 

func (c *Client) RequestWithOptions(opts DHCP4ClientOptions) (bool, dhcp4.Packet, error)

Full DCHP Call With Client Options The Options Should Contain the requested values and the responded values

func (*Client) SendDecline 

func (c *Client) SendDecline(acknowledgementPacket *dhcp4.Packet) (declinePacket dhcp4.Packet, err error)

Send Decline to the received acknowledgement.

func (*Client) SendDiscoverPacket 

func (c *Client) SendDiscoverPacket() (dhcp4.Packet, error)

Send the Discovery Packet to the Broadcast Channel

func (*Client) SendDiscoverPacketWithOptions 

func (c *Client) SendDiscoverPacketWithOptions(opts DHCP4ClientOptions) (dhcp4.Packet, error)

func (*Client) SendRequestFromOfferPacket 

func (c *Client) SendRequestFromOfferPacket(offerPacket *dhcp4.Packet) (dhcp4.Packet, error)

Send Request Based On the offer Received.

func (*Client) SendRequestFromOfferPacketWithOptions 

func (c *Client) SendRequestFromOfferPacketWithOptions(offerPacket *dhcp4.Packet, opts DHCP4ClientOptions) (requestPacket dhcp4.Packet, err error)

func (*Client) SetLaddr 

func (c *Client) SetLaddr(l *net.UDPAddr)

SetLaddr allows you to change the Local Address used by the Client to make request. This is normally used after you've obtained an IP and brought your interface up to make renewal requests to the DHCP Server.

func (*Client) SetOption 

func (c *Client) SetOption(options ...func(*Client) error) error

SetOptions allows you to configure the client. Generally you should be setting the functional options on the creation of the instance.

func (*Client) UnicastPacket 

func (c *Client) UnicastPacket(p dhcp4.Packet) (i int, err error)

UnicastPacket Allows you to Unicast Packets to the server passed in the dhcp4.OptionServerIdentifier DHCP4 Packet option. BUG(d2g): Hardcoded to contect the server on port 67.

type DHCP4ClientOptions 

type DHCP4ClientOptions map[dhcp4.MessageType][]*dhcp4.Option

DHCP4ClientOptions is used to GET & SET custom DHCP Options in the requests and response packets. The dhcp4.Options is passed in with the values you want to set and those that you want to retreive. The reason that the value is a map is so that all options can be GET at any stage of the request lifecycle in a single call to the RequestWithOptions().

func (DHCP4ClientOptions) String 

func (o DHCP4ClientOptions) String() string

TODO(d2g): Tidy Up

type DHCP4Error 

type DHCP4Error struct {
	Err         error    // Child Error
	OpCode      int      // The DHCP option code of the action
	Src         net.Addr // connection source
	Dest        net.Addr // destination source
	IsTimeout   bool     // if true, timed out; not all timeouts set this
	IsTemporary bool     // if true, error is temporary; not all errors set this
}

An Error Type with aditoin DHCP4 information.

func (*DHCP4Error) Error 

func (e *DHCP4Error) Error() string

func (*DHCP4Error) Temporary 

func (e *DHCP4Error) Temporary() bool

func (*DHCP4Error) Timeout 

func (e *DHCP4Error) Timeout() bool

Notes

Bugs

Source Files

View all Source files

Directories

Path Synopsis
inetsocket
pktsocket
testsocket

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