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package dhcpv6
// This module defines the OptUserClass structure.
// https://www.ietf.org/rfc/rfc3315.txt
import (
"encoding/binary"
"errors"
"fmt"
"strings"
)
// OptUserClass represent a DHCPv6 User Class option
type OptUserClass struct {
UserClasses [][]byte
}
// Code returns the option code
func (op *OptUserClass) Code() OptionCode {
return OPTION_USER_CLASS
}
// ToBytes serializes the option and returns it as a sequence of bytes
func (op *OptUserClass) ToBytes() []byte {
buf := make([]byte, 4)
binary.BigEndian.PutUint16(buf[0:2], uint16(OPTION_USER_CLASS))
binary.BigEndian.PutUint16(buf[2:4], uint16(op.Length()))
u16 := make([]byte, 2)
for _, uc := range op.UserClasses {
binary.BigEndian.PutUint16(u16, uint16(len(uc)))
buf = append(buf, u16...)
buf = append(buf, uc...)
}
return buf
}
// Length returns the option length
func (op *OptUserClass) Length() int {
ret := 0
for _, uc := range op.UserClasses {
ret += 2 + len(uc)
}
return ret
}
func (op *OptUserClass) String() string {
ucStrings := make([]string, 0)
for _, uc := range op.UserClasses {
ucStrings = append(ucStrings, string(uc))
}
return fmt.Sprintf("OptUserClass{userclass=[%s]}", strings.Join(ucStrings, ", "))
}
// ParseOptUserClass builds an OptUserClass structure from a sequence of
// bytes. The input data does not include option code and length bytes.
func ParseOptUserClass(data []byte) (*OptUserClass, error) {
opt := OptUserClass{}
for {
if len(data) == 0 {
break
}
if len(data) < 2 {
return nil, errors.New("ParseOptUserClass: short data: missing length field")
}
ucLen := int(binary.BigEndian.Uint16(data[:2]))
if len(data) < ucLen+2 {
return nil, fmt.Errorf("ParseOptUserClass: short data: less than %d bytes", ucLen+2)
}
opt.UserClasses = append(opt.UserClasses, data[2:ucLen+2])
data = data[2+ucLen:]
}
if len(opt.UserClasses) < 1 {
return nil, errors.New("ParseOptUserClass: at least one user class is required")
}
return &opt, nil
}
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