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package dhcpv6
import (
"encoding/binary"
"fmt"
)
// OptionCode is a single byte representing the code for a given Option.
type OptionCode uint16
// Option is an interface that all DHCPv6 options adhere to.
type Option interface {
Code() OptionCode
ToBytes() []byte
Length() int
String() string
}
type OptionGeneric struct {
OptionCode OptionCode
OptionData []byte
}
func (og *OptionGeneric) Code() OptionCode {
return og.OptionCode
}
func (og *OptionGeneric) ToBytes() []byte {
var ret []byte
codeBytes := make([]byte, 2)
binary.BigEndian.PutUint16(codeBytes, uint16(og.OptionCode))
ret = append(ret, codeBytes...)
lengthBytes := make([]byte, 2)
binary.BigEndian.PutUint16(lengthBytes, uint16(len(og.OptionData)))
ret = append(ret, lengthBytes...)
ret = append(ret, og.OptionData...)
return ret
}
func (og *OptionGeneric) String() string {
code, ok := OptionCodeToString[og.OptionCode]
if !ok {
code = "UnknownOption"
}
return fmt.Sprintf("%v -> %v", code, og.OptionData)
}
func (og *OptionGeneric) Length() int {
return len(og.OptionData)
}
func ParseOption(dataStart []byte) (Option, error) {
// Parse a sequence of bytes as a single DHCPv6 option.
// Returns the option structure, or an error if any.
if len(dataStart) < 4 {
return nil, fmt.Errorf("Invalid DHCPv6 option: less than 4 bytes")
}
code := OptionCode(binary.BigEndian.Uint16(dataStart[:2]))
length := int(binary.BigEndian.Uint16(dataStart[2:4]))
if len(dataStart) < length+4 {
return nil, fmt.Errorf("Invalid option length for option %v. Declared %v, actual %v",
code, length, len(dataStart)-4,
)
}
var (
err error
opt Option
)
optData := dataStart[4 : 4+length]
switch code {
case OptionClientID:
opt, err = ParseOptClientId(optData)
case OptionServerID:
opt, err = ParseOptServerId(optData)
case OptionIANA:
opt, err = ParseOptIANA(optData)
case OptionIAAddr:
opt, err = ParseOptIAAddress(optData)
case OptionORO:
opt, err = ParseOptRequestedOption(optData)
case OptionElapsedTime:
opt, err = ParseOptElapsedTime(optData)
case OptionRelayMsg:
opt, err = ParseOptRelayMsg(optData)
case OptionStatusCode:
opt, err = ParseOptStatusCode(optData)
case OptionUserClass:
opt, err = ParseOptUserClass(optData)
case OptionVendorClass:
opt, err = ParseOptVendorClass(optData)
case OptionVendorOpts:
opt, err = ParseOptVendorOpts(optData)
case OptionInterfaceID:
opt, err = ParseOptInterfaceId(optData)
case OptionDNSRecursiveNameServer:
opt, err = ParseOptDNSRecursiveNameServer(optData)
case OptionDomainSearchList:
opt, err = ParseOptDomainSearchList(optData)
case OptionIAPD:
opt, err = ParseOptIAForPrefixDelegation(optData)
case OptionIAPrefix:
opt, err = ParseOptIAPrefix(optData)
case OptionRemoteID:
opt, err = ParseOptRemoteId(optData)
case OptionBootfileURL:
opt, err = ParseOptBootFileURL(optData)
case OptionClientArchType:
opt, err = ParseOptClientArchType(optData)
case OptionNII:
opt, err = ParseOptNetworkInterfaceId(optData)
default:
opt = &OptionGeneric{OptionCode: code, OptionData: optData}
}
if err != nil {
return nil, err
}
if length != opt.Length() {
return nil, fmt.Errorf("Error: declared length is different from actual length for option %d: %d != %d",
code, opt.Length(), length)
}
return opt, nil
}
// Options is a collection of options.
type Options []Option
// Get returns all options matching the option code.
func (o Options) Get(code OptionCode) []Option {
var ret []Option
for _, opt := range o {
if opt.Code() == code {
ret = append(ret, opt)
}
}
return ret
}
// GetOne returns the first option matching the option code.
func (o Options) GetOne(code OptionCode) Option {
for _, opt := range o {
if opt.Code() == code {
return opt
}
}
return nil
}
// Add appends one option.
func (o *Options) Add(option Option) {
*o = append(*o, option)
}
// Del deletes all options matching the option code.
func (o *Options) Del(code OptionCode) {
newOpts := make(Options, 0, len(*o))
for _, opt := range *o {
if opt.Code() != code {
newOpts = append(newOpts, opt)
}
}
*o = newOpts
}
// Update replaces the first option of the same type as the specified one.
func (o *Options) Update(option Option) {
for idx, opt := range *o {
if opt.Code() == option.Code() {
(*o)[idx] = option
// don't look further
return
}
}
// if not found, add it
o.Add(option)
}
// FromBytes reads data into o and returns an error if the options are not a
// valid serialized representation of DHCPv6 options per RFC 3315.
func (o *Options) FromBytes(data []byte) error {
return o.FromBytesWithParser(data, ParseOption)
}
// OptionParser is a function signature for option parsing
type OptionParser func(data []byte) (Option, error)
// FromBytesWithParser parses Options from byte sequences using the parsing
// function that is passed in as a paremeter
func (o *Options) FromBytesWithParser(data []byte, parser OptionParser) error {
// Parse a sequence of bytes until the end and build a list of options from
// it. Returns an error if any invalid option or length is found.
*o = make(Options, 0, 10)
if len(data) == 0 {
// no options, no party
return nil
}
if len(data) < 4 {
// cannot be shorter than option code (2 bytes) + length (2 bytes)
return fmt.Errorf("Invalid options: shorter than 4 bytes")
}
idx := 0
for {
if idx == len(data) {
break
}
if idx > len(data) {
// this should never happen
return fmt.Errorf("Error: reading past the end of options")
}
opt, err := parser(data[idx:])
if err != nil {
return err
}
*o = append(*o, opt)
idx += opt.Length() + 4 // 4 bytes for type + length
}
return nil
}
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