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// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 icmp

import (
	"fmt"
	"net"
)

// In order for the icmpTuple to be used as hashtable key, it needs to have
// a fixed size. This means the net.IP is problematic because it's internally
// represented as a slice. Therefore the hashableIcmpTuple type is introduced
// which internally is a simple byte array.

const maxIcmpTupleRawSize = 1 + 16 + 16 + 2 + 2

type hashableIcmpTuple [maxIcmpTupleRawSize]byte

type icmpTuple struct {
	icmpVersion uint8
	srcIP       net.IP
	dstIP       net.IP
	id          uint16
	seq         uint16
}

func (t *icmpTuple) Reverse() icmpTuple {
	return icmpTuple{
		icmpVersion: t.icmpVersion,
		srcIP:       t.dstIP,
		dstIP:       t.srcIP,
		id:          t.id,
		seq:         t.seq,
	}
}

func (t *icmpTuple) Hashable() hashableIcmpTuple {
	var hash hashableIcmpTuple
	copy(hash[0:16], t.srcIP)
	copy(hash[16:32], t.dstIP)
	copy(hash[32:37], []byte{byte(t.id >> 8), byte(t.id), byte(t.seq >> 8), byte(t.seq), t.icmpVersion})
	return hash
}

func (t *icmpTuple) String() string {
	return fmt.Sprintf("icmpTuple version[%d] src[%s] dst[%s] id[%d] seq[%d]",
		t.icmpVersion, t.srcIP, t.dstIP, t.id, t.seq)
}