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package dhcpv4
import (
"bytes"
"encoding/binary"
"fmt"
)
// This option implements the Vendor-Identifying Vendor Class Option
// https://tools.ietf.org/html/rfc3925
// VIVCIdentifier represents one Vendor-Identifying vendor class option.
type VIVCIdentifier struct {
EntID uint32
Data []byte
}
// OptVIVC represents the DHCP message type option.
type OptVIVC struct {
Identifiers []VIVCIdentifier
}
// ParseOptVIVC contructs an OptVIVC tsruct from a sequence of bytes and returns
// it, or an error.
func ParseOptVIVC(data []byte) (*OptVIVC, error) {
if len(data) < 2 {
return nil, ErrShortByteStream
}
code := OptionCode(data[0])
if code != OptionVendorIdentifyingVendorClass {
return nil, fmt.Errorf("expected code %v, got %v", OptionVendorIdentifyingVendorClass, code)
}
length := int(data[1])
data = data[2:]
if length != len(data) {
return nil, ErrShortByteStream
}
ids := []VIVCIdentifier{}
for len(data) > 5 {
entID := binary.BigEndian.Uint32(data[0:4])
idLen := int(data[4])
data = data[5:]
if idLen > len(data) {
return nil, ErrShortByteStream
}
ids = append(ids, VIVCIdentifier{EntID: entID, Data: data[:idLen]})
data = data[idLen:]
}
if len(data) != 0 {
return nil, ErrShortByteStream
}
return &OptVIVC{Identifiers: ids}, nil
}
// Code returns the option code.
func (o *OptVIVC) Code() OptionCode {
return OptionVendorIdentifyingVendorClass
}
// ToBytes returns a serialized stream of bytes for this option.
func (o *OptVIVC) ToBytes() []byte {
buf := make([]byte, o.Length()+2)
copy(buf[0:], []byte{byte(o.Code()), byte(o.Length())})
b := buf[2:]
for _, id := range o.Identifiers {
binary.BigEndian.PutUint32(b[0:4], id.EntID)
b[4] = byte(len(id.Data))
copy(b[5:], id.Data)
b = b[len(id.Data)+5:]
}
return buf
}
// String returns a human-readable string for this option.
func (o *OptVIVC) String() string {
buf := bytes.Buffer{}
fmt.Fprintf(&buf, "Vendor-Identifying Vendor Class ->")
for _, id := range o.Identifiers {
fmt.Fprintf(&buf, " %d:'%s',", id.EntID, id.Data)
}
return buf.String()[:buf.Len()-1]
}
// Length returns the length of the data portion (excluding option code and byte
// for length, if any).
func (o *OptVIVC) Length() int {
n := 0
for _, id := range o.Identifiers {
// each class has a header of endID (4 bytes) and length (1 byte)
n += 5 + len(id.Data)
}
return n
}
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