nuclei/v2/pkg/operators/common/dsl/dsl.go

761 lines
24 KiB
Go

package dsl
import (
"bytes"
"compress/gzip"
"compress/zlib"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/md5"
crand "crypto/rand"
"crypto/sha1"
"crypto/sha256"
"encoding/base64"
"encoding/hex"
"fmt"
"hash"
"html"
"io"
"math"
"math/rand"
"net/url"
"regexp"
"sort"
"strconv"
"strings"
"time"
"github.com/pkg/errors"
"github.com/Knetic/govaluate"
"github.com/asaskevich/govalidator"
"github.com/hashicorp/go-version"
"github.com/logrusorgru/aurora"
"github.com/spaolacci/murmur3"
"github.com/projectdiscovery/gologger"
"github.com/projectdiscovery/nuclei/v2/pkg/protocols/common/helpers/deserialization"
"github.com/projectdiscovery/nuclei/v2/pkg/protocols/common/randomip"
"github.com/projectdiscovery/nuclei/v2/pkg/types"
)
const (
numbers = "1234567890"
letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
)
var invalidDslFunctionError = errors.New("invalid DSL function signature")
var invalidDslFunctionMessageTemplate = "%w. correct method signature %q"
var dslFunctions map[string]dslFunction
var functionSignaturePattern = regexp.MustCompile(`(\w+)\s*\((?:([\w\d,\s]+)\s+([.\w\d{}&*]+))?\)([\s.\w\d{}&*]+)?`)
var dateFormatRegex = regexp.MustCompile("%([A-Za-z])")
type dslFunction struct {
signature string
expressFunc govaluate.ExpressionFunction
}
func init() {
tempDslFunctions := map[string]func(string) dslFunction{
"len": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
length := len(types.ToString(args[0]))
return float64(length), nil
}),
"to_upper": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return strings.ToUpper(types.ToString(args[0])), nil
}),
"to_lower": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return strings.ToLower(types.ToString(args[0])), nil
}),
"repeat": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
count, err := strconv.Atoi(types.ToString(args[1]))
if err != nil {
return nil, invalidDslFunctionError
}
return strings.Repeat(types.ToString(args[0]), count), nil
}),
"replace": makeDslFunction(3, func(args ...interface{}) (interface{}, error) {
return strings.ReplaceAll(types.ToString(args[0]), types.ToString(args[1]), types.ToString(args[2])), nil
}),
"replace_regex": makeDslFunction(3, func(args ...interface{}) (interface{}, error) {
compiled, err := regexp.Compile(types.ToString(args[1]))
if err != nil {
return nil, err
}
return compiled.ReplaceAllString(types.ToString(args[0]), types.ToString(args[2])), nil
}),
"trim": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
return strings.Trim(types.ToString(args[0]), types.ToString(args[1])), nil
}),
"trim_left": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
return strings.TrimLeft(types.ToString(args[0]), types.ToString(args[1])), nil
}),
"trim_right": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
return strings.TrimRight(types.ToString(args[0]), types.ToString(args[1])), nil
}),
"trim_space": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return strings.TrimSpace(types.ToString(args[0])), nil
}),
"trim_prefix": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
return strings.TrimPrefix(types.ToString(args[0]), types.ToString(args[1])), nil
}),
"trim_suffix": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
return strings.TrimSuffix(types.ToString(args[0]), types.ToString(args[1])), nil
}),
"reverse": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return reverseString(types.ToString(args[0])), nil
}),
"base64": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return base64.StdEncoding.EncodeToString([]byte(types.ToString(args[0]))), nil
}),
"gzip": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
buffer := &bytes.Buffer{}
writer := gzip.NewWriter(buffer)
if _, err := writer.Write([]byte(args[0].(string))); err != nil {
_ = writer.Close()
return "", err
}
_ = writer.Close()
return buffer.String(), nil
}),
"gzip_decode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
reader, err := gzip.NewReader(strings.NewReader(args[0].(string)))
if err != nil {
return "", err
}
data, err := io.ReadAll(reader)
if err != nil {
_ = reader.Close()
return "", err
}
_ = reader.Close()
return string(data), nil
}),
"zlib": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
buffer := &bytes.Buffer{}
writer := zlib.NewWriter(buffer)
if _, err := writer.Write([]byte(args[0].(string))); err != nil {
_ = writer.Close()
return "", err
}
_ = writer.Close()
return buffer.String(), nil
}),
"zlib_decode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
reader, err := zlib.NewReader(strings.NewReader(args[0].(string)))
if err != nil {
return "", err
}
data, err := io.ReadAll(reader)
if err != nil {
_ = reader.Close()
return "", err
}
_ = reader.Close()
return string(data), nil
}),
"date_time": makeDslWithOptionalArgsFunction(
"(dateTimeFormat string, optionalUnixTime interface{}) string",
func(arguments ...interface{}) (interface{}, error) {
dateTimeFormat := types.ToString(arguments[0])
dateTimeFormatFragment := dateFormatRegex.FindAllStringSubmatch(dateTimeFormat, -1)
argumentsSize := len(arguments)
if argumentsSize < 1 && argumentsSize > 2 {
return nil, errors.New("invalid number of arguments")
}
currentTime, err := getCurrentTimeFromUserInput(arguments)
if err != nil {
return nil, err
}
if len(dateTimeFormatFragment) > 0 {
return doSimpleTimeFormat(dateTimeFormatFragment, currentTime, dateTimeFormat)
} else {
return currentTime.Format(dateTimeFormat), nil
}
},
),
"base64_py": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
// python encodes to base64 with lines of 76 bytes terminated by new line "\n"
stdBase64 := base64.StdEncoding.EncodeToString([]byte(types.ToString(args[0])))
return deserialization.InsertInto(stdBase64, 76, '\n'), nil
}),
"base64_decode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
data, err := base64.StdEncoding.DecodeString(types.ToString(args[0]))
return string(data), err
}),
"url_encode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return url.QueryEscape(types.ToString(args[0])), nil
}),
"url_decode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return url.QueryUnescape(types.ToString(args[0]))
}),
"hex_encode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return hex.EncodeToString([]byte(types.ToString(args[0]))), nil
}),
"hex_decode": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
decodeString, err := hex.DecodeString(types.ToString(args[0]))
return string(decodeString), err
}),
"hmac": makeDslFunction(3, func(args ...interface{}) (interface{}, error) {
hashAlgorithm := args[0]
data := args[1].(string)
secretKey := args[2].(string)
var hashFunction func() hash.Hash
switch hashAlgorithm {
case "sha1", "sha-1":
hashFunction = sha1.New
case "sha256", "sha-256":
hashFunction = sha256.New
default:
return nil, fmt.Errorf("unsupported hash algorithm: '%s'", hashAlgorithm)
}
h := hmac.New(hashFunction, []byte(secretKey))
h.Write([]byte(data))
return hex.EncodeToString(h.Sum(nil)), nil
}),
"html_escape": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return html.EscapeString(types.ToString(args[0])), nil
}),
"html_unescape": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return html.UnescapeString(types.ToString(args[0])), nil
}),
"md5": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return toHexEncodedHash(md5.New(), types.ToString(args[0]))
}),
"sha256": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return toHexEncodedHash(sha256.New(), types.ToString(args[0]))
}),
"sha1": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return toHexEncodedHash(sha1.New(), types.ToString(args[0]))
}),
"mmh3": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
hasher := murmur3.New32WithSeed(0)
hasher.Write([]byte(fmt.Sprint(args[0])))
return fmt.Sprintf("%d", int32(hasher.Sum32())), nil
}),
"contains": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
return strings.Contains(types.ToString(args[0]), types.ToString(args[1])), nil
}),
"concat": makeDslWithOptionalArgsFunction(
"(args ...interface{}) string",
func(arguments ...interface{}) (interface{}, error) {
builder := &strings.Builder{}
for _, argument := range arguments {
builder.WriteString(types.ToString(argument))
}
return builder.String(), nil
},
),
"join": makeDslWithOptionalArgsFunction(
"(separator string, elements ...interface{}) string",
func(arguments ...interface{}) (interface{}, error) {
argumentsSize := len(arguments)
if argumentsSize < 2 {
return nil, errors.New("incorrect number of arguments received")
}
separator := types.ToString(arguments[0])
elements := arguments[1:argumentsSize]
stringElements := make([]string, 0, argumentsSize)
for _, element := range elements {
stringElements = append(stringElements, types.ToString(element))
}
return strings.Join(stringElements, separator), nil
},
),
"regex": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
compiled, err := regexp.Compile(types.ToString(args[0]))
if err != nil {
return nil, err
}
return compiled.MatchString(types.ToString(args[1])), nil
}),
"remove_bad_chars": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
input := types.ToString(args[0])
badChars := types.ToString(args[1])
return trimAll(input, badChars), nil
}),
"rand_char": makeDslWithOptionalArgsFunction(
"(optionalCharSet string) string",
func(args ...interface{}) (interface{}, error) {
charSet := letters + numbers
argSize := len(args)
if argSize != 0 && argSize != 1 {
return nil, invalidDslFunctionError
}
if argSize >= 1 {
inputCharSet := types.ToString(args[0])
if strings.TrimSpace(inputCharSet) != "" {
charSet = inputCharSet
}
}
return string(charSet[rand.Intn(len(charSet))]), nil
},
),
"rand_base": makeDslWithOptionalArgsFunction(
"(length uint, optionalCharSet string) string",
func(args ...interface{}) (interface{}, error) {
var length int
charSet := letters + numbers
argSize := len(args)
if argSize < 1 || argSize > 3 {
return nil, invalidDslFunctionError
}
length = int(args[0].(float64))
if argSize == 2 {
inputCharSet := types.ToString(args[1])
if strings.TrimSpace(inputCharSet) != "" {
charSet = inputCharSet
}
}
return randSeq(charSet, length), nil
},
),
"rand_text_alphanumeric": makeDslWithOptionalArgsFunction(
"(length uint, optionalBadChars string) string",
func(args ...interface{}) (interface{}, error) {
length := 0
badChars := ""
argSize := len(args)
if argSize != 1 && argSize != 2 {
return nil, invalidDslFunctionError
}
length = int(args[0].(float64))
if argSize == 2 {
badChars = types.ToString(args[1])
}
chars := trimAll(letters+numbers, badChars)
return randSeq(chars, length), nil
},
),
"rand_text_alpha": makeDslWithOptionalArgsFunction(
"(length uint, optionalBadChars string) string",
func(args ...interface{}) (interface{}, error) {
var length int
badChars := ""
argSize := len(args)
if argSize != 1 && argSize != 2 {
return nil, invalidDslFunctionError
}
length = int(args[0].(float64))
if argSize == 2 {
badChars = types.ToString(args[1])
}
chars := trimAll(letters, badChars)
return randSeq(chars, length), nil
},
),
"rand_text_numeric": makeDslWithOptionalArgsFunction(
"(length uint, optionalBadNumbers string) string",
func(args ...interface{}) (interface{}, error) {
argSize := len(args)
if argSize != 1 && argSize != 2 {
return nil, invalidDslFunctionError
}
length := int(args[0].(float64))
badNumbers := ""
if argSize == 2 {
badNumbers = types.ToString(args[1])
}
chars := trimAll(numbers, badNumbers)
return randSeq(chars, length), nil
},
),
"rand_int": makeDslWithOptionalArgsFunction(
"(optionalMin, optionalMax uint) int",
func(args ...interface{}) (interface{}, error) {
argSize := len(args)
if argSize > 2 {
return nil, invalidDslFunctionError
}
min := 0
max := math.MaxInt32
if argSize >= 1 {
min = int(args[0].(float64))
}
if argSize == 2 {
max = int(args[1].(float64))
}
return rand.Intn(max-min) + min, nil
},
),
"rand_ip": makeDslWithOptionalArgsFunction(
"(cidr ...string) string",
func(args ...interface{}) (interface{}, error) {
if len(args) == 0 {
return nil, invalidDslFunctionError
}
var cidrs []string
for _, arg := range args {
cidrs = append(cidrs, arg.(string))
}
return randomip.GetRandomIPWithCidr(cidrs...)
}),
"generate_java_gadget": makeDslFunction(3, func(args ...interface{}) (interface{}, error) {
gadget := args[0].(string)
cmd := args[1].(string)
encoding := args[2].(string)
data := deserialization.GenerateJavaGadget(gadget, cmd, encoding)
return data, nil
}),
"unix_time": makeDslWithOptionalArgsFunction(
"(optionalSeconds uint) float64",
func(args ...interface{}) (interface{}, error) {
seconds := 0
argSize := len(args)
if argSize != 0 && argSize != 1 {
return nil, invalidDslFunctionError
} else if argSize == 1 {
seconds = int(args[0].(float64))
}
offset := time.Now().Add(time.Duration(seconds) * time.Second)
return float64(offset.Unix()), nil
},
),
"wait_for": makeDslWithOptionalArgsFunction(
"(seconds uint)",
func(args ...interface{}) (interface{}, error) {
if len(args) != 1 {
return nil, invalidDslFunctionError
}
seconds := args[0].(float64)
time.Sleep(time.Duration(seconds) * time.Second)
return true, nil
},
),
"compare_versions": makeDslWithOptionalArgsFunction(
"(firstVersion, constraints ...string) bool",
func(args ...interface{}) (interface{}, error) {
if len(args) < 2 {
return nil, invalidDslFunctionError
}
firstParsed, parseErr := version.NewVersion(types.ToString(args[0]))
if parseErr != nil {
return nil, parseErr
}
var versionConstraints []string
for _, constraint := range args[1:] {
versionConstraints = append(versionConstraints, types.ToString(constraint))
}
constraint, constraintErr := version.NewConstraint(strings.Join(versionConstraints, ","))
if constraintErr != nil {
return nil, constraintErr
}
result := constraint.Check(firstParsed)
return result, nil
},
),
"print_debug": makeDslWithOptionalArgsFunction(
"(args ...interface{})",
func(args ...interface{}) (interface{}, error) {
if len(args) < 1 {
return nil, invalidDslFunctionError
}
gologger.Info().Msgf("print_debug value: %s", fmt.Sprint(args))
return true, nil
},
),
"to_number": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
argStr := types.ToString(args[0])
if govalidator.IsInt(argStr) {
sint, err := strconv.Atoi(argStr)
return float64(sint), err
} else if govalidator.IsFloat(argStr) {
sint, err := strconv.ParseFloat(argStr, 64)
return float64(sint), err
}
return nil, errors.Errorf("%v could not be converted to int", argStr)
}),
"to_string": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
return types.ToString(args[0]), nil
}),
"dec_to_hex": makeDslFunction(1, func(args ...interface{}) (interface{}, error) {
if number, ok := args[0].(float64); ok {
hexNum := strconv.FormatInt(int64(number), 16)
return types.ToString(hexNum), nil
}
return nil, fmt.Errorf("invalid number: %T", args[0])
}),
"aes_gcm": makeDslFunction(2, func(args ...interface{}) (interface{}, error) {
key := args[0].(string)
value := args[1].(string)
c, err := aes.NewCipher([]byte(key))
if nil != err {
return "", err
}
gcm, err := cipher.NewGCM(c)
if nil != err {
return "", err
}
nonce := make([]byte, gcm.NonceSize())
if _, err = io.ReadFull(crand.Reader, nonce); err != nil {
return "", err
}
data := gcm.Seal(nonce, nonce, []byte(value), nil)
return data, nil
}),
}
dslFunctions = make(map[string]dslFunction, len(tempDslFunctions))
for funcName, dslFunc := range tempDslFunctions {
dslFunctions[funcName] = dslFunc(funcName)
}
}
func makeDslWithOptionalArgsFunction(signaturePart string, dslFunctionLogic govaluate.ExpressionFunction) func(functionName string) dslFunction {
return func(functionName string) dslFunction {
return dslFunction{
functionName + signaturePart,
dslFunctionLogic,
}
}
}
func makeDslFunction(numberOfParameters int, dslFunctionLogic govaluate.ExpressionFunction) func(functionName string) dslFunction {
return func(functionName string) dslFunction {
signature := functionName + createSignaturePart(numberOfParameters)
return dslFunction{
signature,
func(args ...interface{}) (interface{}, error) {
if len(args) != numberOfParameters {
return nil, fmt.Errorf(invalidDslFunctionMessageTemplate, invalidDslFunctionError, signature)
}
return dslFunctionLogic(args...)
},
}
}
}
func createSignaturePart(numberOfParameters int) string {
params := make([]string, 0, numberOfParameters)
for i := 1; i <= numberOfParameters; i++ {
params = append(params, "arg"+strconv.Itoa(i))
}
return fmt.Sprintf("(%s interface{}) interface{}", strings.Join(params, ", "))
}
// HelperFunctions returns the dsl helper functions
func HelperFunctions() map[string]govaluate.ExpressionFunction {
helperFunctions := make(map[string]govaluate.ExpressionFunction, len(dslFunctions))
for functionName, dslFunction := range dslFunctions {
helperFunctions[functionName] = dslFunction.expressFunc
helperFunctions[strings.ReplaceAll(functionName, "_", "")] = dslFunction.expressFunc // for backwards compatibility
}
return helperFunctions
}
// AddHelperFunction allows creation of additional helper functions to be supported with templates
//goland:noinspection GoUnusedExportedFunction
func AddHelperFunction(key string, value func(args ...interface{}) (interface{}, error)) error {
if _, ok := dslFunctions[key]; !ok {
dslFunction := dslFunctions[key]
dslFunction.signature = "(args ...interface{}) interface{}"
dslFunction.expressFunc = value
return nil
}
return errors.New("duplicate helper function key defined")
}
func GetPrintableDslFunctionSignatures(noColor bool) string {
aggregateSignatures := func(values []string) string {
sort.Strings(values)
builder := &strings.Builder{}
for _, value := range values {
builder.WriteRune('\t')
builder.WriteString(value)
builder.WriteRune('\n')
}
return builder.String()
}
if noColor {
return aggregateSignatures(getDslFunctionSignatures())
}
return aggregateSignatures(colorizeDslFunctionSignatures())
}
func getDslFunctionSignatures() []string {
result := make([]string, 0, len(dslFunctions))
for _, dslFunction := range dslFunctions {
result = append(result, dslFunction.signature)
}
return result
}
func colorizeDslFunctionSignatures() []string {
signatures := getDslFunctionSignatures()
colorToOrange := func(value string) string {
return aurora.Index(208, value).String()
}
result := make([]string, 0, len(signatures))
for _, signature := range signatures {
subMatchSlices := functionSignaturePattern.FindAllStringSubmatch(signature, -1)
if len(subMatchSlices) != 1 {
// TODO log when #1166 is implemented
return signatures
}
matches := subMatchSlices[0]
if len(matches) != 5 {
// TODO log when #1166 is implemented
return signatures
}
functionParameters := strings.Split(matches[2], ",")
var coloredParameterAndTypes []string
for _, functionParameter := range functionParameters {
functionParameter = strings.TrimSpace(functionParameter)
paramAndType := strings.Split(functionParameter, " ")
if len(paramAndType) == 1 {
coloredParameterAndTypes = append(coloredParameterAndTypes, paramAndType[0])
} else if len(paramAndType) == 2 {
coloredParameterAndTypes = append(coloredParameterAndTypes, fmt.Sprintf("%s %s", paramAndType[0], colorToOrange(paramAndType[1])))
}
}
highlightedParams := strings.TrimSpace(fmt.Sprintf("%s %s", strings.Join(coloredParameterAndTypes, ", "), colorToOrange(matches[3])))
colorizedDslSignature := fmt.Sprintf("%s(%s)%s", aurora.BrightYellow(matches[1]).String(), highlightedParams, colorToOrange(matches[4]))
result = append(result, colorizedDslSignature)
}
return result
}
func reverseString(s string) string {
runes := []rune(s)
for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
runes[i], runes[j] = runes[j], runes[i]
}
return string(runes)
}
func trimAll(s, cutset string) string {
for _, c := range cutset {
s = strings.ReplaceAll(s, string(c), "")
}
return s
}
func randSeq(base string, n int) string {
b := make([]rune, n)
for i := range b {
b[i] = rune(base[rand.Intn(len(base))])
}
return string(b)
}
func toHexEncodedHash(hashToUse hash.Hash, data string) (interface{}, error) {
if _, err := hashToUse.Write([]byte(data)); err != nil {
return nil, err
}
return hex.EncodeToString(hashToUse.Sum(nil)), nil
}
func doSimpleTimeFormat(dateTimeFormatFragment [][]string, currentTime time.Time, dateTimeFormat string) (interface{}, error) {
for _, currentFragment := range dateTimeFormatFragment {
if len(currentFragment) < 2 {
continue
}
prefixedFormatFragment := currentFragment[0]
switch currentFragment[1] {
case "Y", "y":
dateTimeFormat = formatDateTime(dateTimeFormat, prefixedFormatFragment, currentTime.Year())
case "M":
dateTimeFormat = formatDateTime(dateTimeFormat, prefixedFormatFragment, int(currentTime.Month()))
case "D", "d":
dateTimeFormat = formatDateTime(dateTimeFormat, prefixedFormatFragment, currentTime.Day())
case "H", "h":
dateTimeFormat = formatDateTime(dateTimeFormat, prefixedFormatFragment, currentTime.Hour())
case "m":
dateTimeFormat = formatDateTime(dateTimeFormat, prefixedFormatFragment, currentTime.Minute())
case "S", "s":
dateTimeFormat = formatDateTime(dateTimeFormat, prefixedFormatFragment, currentTime.Second())
default:
return nil, fmt.Errorf("invalid date time format string: %s", prefixedFormatFragment)
}
}
return dateTimeFormat, nil
}
func getCurrentTimeFromUserInput(arguments []interface{}) (time.Time, error) {
var currentTime time.Time
if len(arguments) == 2 {
switch inputUnixTime := arguments[1].(type) {
case time.Time:
currentTime = inputUnixTime
case string:
unixTime, err := strconv.ParseInt(inputUnixTime, 10, 64)
if err != nil {
return time.Time{}, errors.New("invalid argument type")
}
currentTime = time.Unix(unixTime, 0)
case int64, float64:
currentTime = time.Unix(int64(inputUnixTime.(float64)), 0)
default:
return time.Time{}, errors.New("invalid argument type")
}
} else {
currentTime = time.Now()
}
return currentTime, nil
}
func formatDateTime(inputFormat string, matchValue string, timeFragment int) string {
return strings.ReplaceAll(inputFormat, matchValue, appendSingleDigitZero(strconv.Itoa(timeFragment)))
}
// appendSingleDigitZero appends zero at front if not exists already doing two digit padding
func appendSingleDigitZero(value string) string {
if len(value) == 1 && (!strings.HasPrefix(value, "0") || value == "0") {
builder := &strings.Builder{}
builder.WriteRune('0')
builder.WriteString(value)
newVal := builder.String()
return newVal
}
return value
}