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package dhcpv4
import (
"encoding/binary"
"fmt"
)
// This option implements the Maximum DHCP Message size option
// https://tools.ietf.org/html/rfc2132
// OptMaximumDHCPMessageSize represents the Maximum DHCP Message size option.
type OptMaximumDHCPMessageSize struct {
Size uint16
}
// ParseOptMaximumDHCPMessageSize constructs an OptMaximumDHCPMessageSize struct from a sequence of
// bytes and returns it, or an error.
func ParseOptMaximumDHCPMessageSize(data []byte) (*OptMaximumDHCPMessageSize, error) {
// Should at least have code, length, and message size.
if len(data) < 4 {
return nil, ErrShortByteStream
}
code := OptionCode(data[0])
if code != OptionMaximumDHCPMessageSize {
return nil, fmt.Errorf("expected option %v, got %v instead", OptionMaximumDHCPMessageSize, code)
}
length := int(data[1])
if length != 2 {
return nil, fmt.Errorf("expected length 2, got %v instead", length)
}
msgSize := binary.BigEndian.Uint16(data[2:4])
return &OptMaximumDHCPMessageSize{Size: msgSize}, nil
}
// Code returns the option code.
func (o *OptMaximumDHCPMessageSize) Code() OptionCode {
return OptionMaximumDHCPMessageSize
}
// ToBytes returns a serialized stream of bytes for this option.
func (o *OptMaximumDHCPMessageSize) ToBytes() []byte {
serializedSize := make([]byte, 2)
binary.BigEndian.PutUint16(serializedSize, o.Size)
serializedOpt := []byte{byte(o.Code()), byte(o.Length())}
return append(serializedOpt, serializedSize...)
}
// String returns a human-readable string for this option.
func (o *OptMaximumDHCPMessageSize) String() string {
return fmt.Sprintf("Maximum DHCP Message Size -> %v", o.Size)
}
// Length returns the length of the data portion (excluding option code and byte
// for length, if any).
func (o *OptMaximumDHCPMessageSize) Length() int {
return 2
}
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