// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package icmp

import (
	"net"

	"github.com/tailscale/xnet/internal/iana"
)

const ipv6PseudoHeaderLen = 2*net.IPv6len + 8

// IPv6PseudoHeader returns an IPv6 pseudo header for checksum
// calculation.
func IPv6PseudoHeader(src, dst net.IP) []byte {
	b := make([]byte, ipv6PseudoHeaderLen)
	copy(b, src.To16())
	copy(b[net.IPv6len:], dst.To16())
	b[len(b)-1] = byte(iana.ProtocolIPv6ICMP)
	return b
}
