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random.go
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random.go
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// Copyright © 2017 The Things Network
// Use of this source code is governed by the MIT license that can be found in the LICENSE file.
package random
import (
"fmt"
"math"
"strings"
"time"
"github.com/TheThingsNetwork/go-utils/pseudorandom"
"github.com/TheThingsNetwork/go-utils/random"
"github.com/TheThingsNetwork/ttn/core/types"
)
// TTNRandom is used as a wrapper around math/rand
type TTNRandom struct {
random.Interface
}
// New returns a new TTNRandom, in most cases you can just use the global funcs
func New() *TTNRandom {
return &TTNRandom{
Interface: pseudorandom.New(time.Now().UnixNano()),
}
}
var global = New()
func (r *TTNRandom) randomChar() byte {
return byte('a' + r.Intn('z'-'a'))
}
func (r *TTNRandom) randomCharString() string {
return string(r.randomChar())
}
func (r *TTNRandom) formatID(s string) string {
switch {
case strings.HasPrefix(s, "-"):
s = strings.TrimPrefix(s, "-") + r.randomCharString()
case strings.HasPrefix(s, "_"):
s = strings.TrimPrefix(s, "_") + r.randomCharString()
case strings.HasSuffix(s, "-"):
s = strings.TrimSuffix(s, "-") + r.randomCharString()
case strings.HasSuffix(s, "_"):
s = strings.TrimSuffix(s, "_") + r.randomCharString()
}
return strings.ToLower(strings.NewReplacer(
"_-", r.randomCharString()+r.randomCharString(),
"-_", r.randomCharString()+r.randomCharString(),
"__", r.randomCharString()+r.randomCharString(),
"--", r.randomCharString()+r.randomCharString(),
).Replace(s))
}
// ID returns randomly generated ID
func (r *TTNRandom) ID() string {
return r.formatID(r.Interface.String(2 + r.Interface.Intn(61)))
}
// AppID returns randomly generated AppID
func (r *TTNRandom) AppID() string {
return r.formatID(r.Interface.String(2 + r.Interface.Intn(34)))
}
// DevID returns randomly generated DevID
func (r *TTNRandom) DevID() string {
return r.formatID(r.Interface.String(2 + r.Interface.Intn(34)))
}
// Bool return randomly generated bool value
func (r *TTNRandom) Bool() bool {
return r.Interface.Intn(2) == 0
}
// Rssi generates RSSI signal between -120 < rssi < 0
func (r *TTNRandom) Rssi() int32 {
// Generate RSSI. Tend towards generating great signal strength.
x := float64(r.Interface.Intn(math.MaxInt32)) * float64(2e-9)
return int32(-1.6 * math.Exp(x))
}
var freqs = []float32{
// EU
868.1,
868.3,
868.5,
868.8,
867.1,
867.3,
867.5,
867.7,
867.9,
// US
903.9,
904.1,
904.3,
904.5,
904.7,
904.9,
905.1,
905.3,
904.6,
}
// Freq generates a frequency between 867.1 and 905.3 Mhz
func (r *TTNRandom) Freq() float32 {
return freqs[r.Interface.Intn(len(freqs))]
}
// Datr generates Datr for instance: SF4BW125
func (r *TTNRandom) Datr() string {
// Spread Factor from 12 to 7
sf := 12 - r.Interface.Intn(7)
var bw int
if sf == 6 {
// DR6 -> SF7@250Khz
sf = 7
bw = 250
} else {
bw = 125
}
return fmt.Sprintf("SF%dBW%d", sf, bw)
}
// Codr generates Codr for instance: 4/6
func (r *TTNRandom) Codr() string {
d := r.Interface.Intn(4) + 5
return fmt.Sprintf("4/%d", d)
}
// Lsnr generates LoRa SNR ratio in db. Tend towards generating good ratio with low noise
func (r *TTNRandom) Lsnr() float32 {
x := float64(r.Interface.Intn(math.MaxInt32)) * float64(2e-9)
return float32(math.Floor((-0.1*math.Exp(x)+5.5)*10) / 10)
}
func (r *TTNRandom) DevNonce() (devNonce types.DevNonce) {
r.Interface.FillBytes(devNonce[:])
return
}
func (r *TTNRandom) AppNonce() (appNonce types.AppNonce) {
r.Interface.FillBytes(appNonce[:])
return
}
func (r *TTNRandom) NetID() (netID types.NetID) {
r.Interface.FillBytes(netID[:])
return
}
func (r *TTNRandom) DevAddr() (devAddr types.DevAddr) {
r.Interface.FillBytes(devAddr[:])
return
}
func (r *TTNRandom) EUI64() (eui types.EUI64) {
r.Interface.FillBytes(eui[:])
return
}
func (r *TTNRandom) DevEUI() (eui types.DevEUI) {
return types.DevEUI(r.EUI64())
}
func (r *TTNRandom) AppEUI() (eui types.AppEUI) {
return types.AppEUI(r.EUI64())
}
// Rssi generates RSSI signal between -120 < rssi < 0
func Rssi() int32 {
return global.Rssi()
}
// Freq generates a frequency between 865.0 and 870.0 Mhz
func Freq() float32 {
return global.Freq()
}
// Datr generates Datr for instance: SF4BW125
func Datr() string {
return global.Datr()
}
// Codr generates Codr for instance: 4/6
func Codr() string {
return global.Codr()
}
// Lsnr generates LoRa SNR ratio in db. Tend towards generating good ratio with low noise
func Lsnr() float32 {
return global.Lsnr()
}
// Intn returns random int with max n
func Intn(n int) int {
return global.Intn(n)
}
// String returns a random string of length n
func String(n int) string {
return global.String(n)
}
// Bytes generates a random byte slice of length n
func Bytes(n int) []byte {
return global.Bytes(n)
}
// Bool generates a random boolean
func Bool() bool {
return global.Bool()
}
func ID() string {
return global.ID()
}
func AppID() string {
return global.AppID()
}
func DevID() string {
return global.DevID()
}
func DevNonce() types.DevNonce {
return global.DevNonce()
}
func AppNonce() types.AppNonce {
return global.AppNonce()
}
func NetID() types.NetID {
return global.NetID()
}
func DevAddr() types.DevAddr {
return global.DevAddr()
}
func EUI64() types.EUI64 {
return global.EUI64()
}
func DevEUI() types.DevEUI {
return global.DevEUI()
}
func AppEUI() types.AppEUI {
return global.AppEUI()
}