You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: stun.go
    path of file: ./repos/sliver/vendor/tailscale.com/net/stun
    
    the code of the file until where you have to start completion: // Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause

// Package STUN generates STUN request packets and parses response packets.
package stun

import (
	"bytes"
	crand "crypto/rand"
	"encoding/binary"
	"errors"
	"hash/crc32"
	"net"
	"net/netip"
)

const (
	attrNumSoftware      = 0x8022
	attrNumFingerprint   = 0x8028
	attrMappedAddress    = 0x0001
	attrXorMappedAddress = 0x00
    
func Request(tID TxID) []byte {
	// STUN header, RFC5389 Section 6.
	const lenAttrSoftware = 4 + len(software)
	b := make([]byte, 0, headerLen+lenAttrSoftware+lenFingerprint)
	b = append(b, bindingRequest...)
	b = appendU16(b, uint16(lenAttrSoftware+lenFingerprint)) // number of bytes following header
	b = append(b, magicCookie...)
	b = append(b, tID[:]...)

	// Attribute SOFTWARE, RFC5389 Section 15.5.
	b = appendU16(b, attrNumSoftware)
	b = appendU16(b, uint16(len(software)))
	b = append(b, software...)

	// Attribute FINGERPRINT, RFC5389 Section 15.5.
	fp := fingerPrint(b)
	b = appendU16(b, attrNumFingerprint)
	b = appendU16(b, 4)
	b = appendU32(b, fp)

	return b
}