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// Copyright 2016 CNI authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package hwaddr
import (
"fmt"
"net"
)
const (
ipRelevantByteLen = 4
PrivateMACPrefixString = "0a:58"
)
var (
// private mac prefix safe to use
PrivateMACPrefix = []byte{0x0a, 0x58}
)
type SupportIp4OnlyErr struct{ msg string }
func (e SupportIp4OnlyErr) Error() string { return e.msg }
type MacParseErr struct{ msg string }
func (e MacParseErr) Error() string { return e.msg }
type InvalidPrefixLengthErr struct{ msg string }
func (e InvalidPrefixLengthErr) Error() string { return e.msg }
// GenerateHardwareAddr4 generates 48 bit virtual mac addresses based on the IP4 input.
func GenerateHardwareAddr4(ip net.IP, prefix []byte) (net.HardwareAddr, error) {
switch {
case ip.To4() == nil:
return nil, SupportIp4OnlyErr{msg: "GenerateHardwareAddr4 only supports valid IPv4 address as input"}
case len(prefix) != len(PrivateMACPrefix):
return nil, InvalidPrefixLengthErr{msg: fmt.Sprintf(
"Prefix has length %d instead of %d", len(prefix), len(PrivateMACPrefix)),
}
}
ipByteLen := len(ip)
return (net.HardwareAddr)(
append(
prefix,
ip[ipByteLen-ipRelevantByteLen:ipByteLen]...),
), nil
}
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