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- /*
- Copyright 2014 Alexander Okoli
- Licensed 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 goutils
- import (
- "crypto/rand"
- "fmt"
- "math"
- "math/big"
- "unicode"
- )
- /*
- CryptoRandomNonAlphaNumeric creates a random string whose length is the number of characters specified.
- Characters will be chosen from the set of all characters (ASCII/Unicode values between 0 to 2,147,483,647 (math.MaxInt32)).
- Parameter:
- count - the length of random string to create
- Returns:
- string - the random string
- error - an error stemming from an invalid parameter within underlying function, CryptoRandom(...)
- */
- func CryptoRandomNonAlphaNumeric(count int) (string, error) {
- return CryptoRandomAlphaNumericCustom(count, false, false)
- }
- /*
- CryptoRandomAscii creates a random string whose length is the number of characters specified.
- Characters will be chosen from the set of characters whose ASCII value is between 32 and 126 (inclusive).
- Parameter:
- count - the length of random string to create
- Returns:
- string - the random string
- error - an error stemming from an invalid parameter within underlying function, CryptoRandom(...)
- */
- func CryptoRandomAscii(count int) (string, error) {
- return CryptoRandom(count, 32, 127, false, false)
- }
- /*
- CryptoRandomNumeric creates a random string whose length is the number of characters specified.
- Characters will be chosen from the set of numeric characters.
- Parameter:
- count - the length of random string to create
- Returns:
- string - the random string
- error - an error stemming from an invalid parameter within underlying function, CryptoRandom(...)
- */
- func CryptoRandomNumeric(count int) (string, error) {
- return CryptoRandom(count, 0, 0, false, true)
- }
- /*
- CryptoRandomAlphabetic creates a random string whose length is the number of characters specified.
- Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
- Parameters:
- count - the length of random string to create
- letters - if true, generated string may include alphabetic characters
- numbers - if true, generated string may include numeric characters
- Returns:
- string - the random string
- error - an error stemming from an invalid parameter within underlying function, CryptoRandom(...)
- */
- func CryptoRandomAlphabetic(count int) (string, error) {
- return CryptoRandom(count, 0, 0, true, false)
- }
- /*
- CryptoRandomAlphaNumeric creates a random string whose length is the number of characters specified.
- Characters will be chosen from the set of alpha-numeric characters.
- Parameter:
- count - the length of random string to create
- Returns:
- string - the random string
- error - an error stemming from an invalid parameter within underlying function, CryptoRandom(...)
- */
- func CryptoRandomAlphaNumeric(count int) (string, error) {
- return CryptoRandom(count, 0, 0, true, true)
- }
- /*
- CryptoRandomAlphaNumericCustom creates a random string whose length is the number of characters specified.
- Characters will be chosen from the set of alpha-numeric characters as indicated by the arguments.
- Parameters:
- count - the length of random string to create
- letters - if true, generated string may include alphabetic characters
- numbers - if true, generated string may include numeric characters
- Returns:
- string - the random string
- error - an error stemming from an invalid parameter within underlying function, CryptoRandom(...)
- */
- func CryptoRandomAlphaNumericCustom(count int, letters bool, numbers bool) (string, error) {
- return CryptoRandom(count, 0, 0, letters, numbers)
- }
- /*
- CryptoRandom creates a random string based on a variety of options, using using golang's crypto/rand source of randomness.
- If the parameters start and end are both 0, start and end are set to ' ' and 'z', the ASCII printable characters, will be used,
- unless letters and numbers are both false, in which case, start and end are set to 0 and math.MaxInt32, respectively.
- If chars is not nil, characters stored in chars that are between start and end are chosen.
- Parameters:
- count - the length of random string to create
- start - the position in set of chars (ASCII/Unicode int) to start at
- end - the position in set of chars (ASCII/Unicode int) to end before
- letters - if true, generated string may include alphabetic characters
- numbers - if true, generated string may include numeric characters
- chars - the set of chars to choose randoms from. If nil, then it will use the set of all chars.
- Returns:
- string - the random string
- error - an error stemming from invalid parameters: if count < 0; or the provided chars array is empty; or end <= start; or end > len(chars)
- */
- func CryptoRandom(count int, start int, end int, letters bool, numbers bool, chars ...rune) (string, error) {
- if count == 0 {
- return "", nil
- } else if count < 0 {
- err := fmt.Errorf("randomstringutils illegal argument: Requested random string length %v is less than 0.", count) // equiv to err := errors.New("...")
- return "", err
- }
- if chars != nil && len(chars) == 0 {
- err := fmt.Errorf("randomstringutils illegal argument: The chars array must not be empty")
- return "", err
- }
- if start == 0 && end == 0 {
- if chars != nil {
- end = len(chars)
- } else {
- if !letters && !numbers {
- end = math.MaxInt32
- } else {
- end = 'z' + 1
- start = ' '
- }
- }
- } else {
- if end <= start {
- err := fmt.Errorf("randomstringutils illegal argument: Parameter end (%v) must be greater than start (%v)", end, start)
- return "", err
- }
- if chars != nil && end > len(chars) {
- err := fmt.Errorf("randomstringutils illegal argument: Parameter end (%v) cannot be greater than len(chars) (%v)", end, len(chars))
- return "", err
- }
- }
- buffer := make([]rune, count)
- gap := end - start
- // high-surrogates range, (\uD800-\uDBFF) = 55296 - 56319
- // low-surrogates range, (\uDC00-\uDFFF) = 56320 - 57343
- for count != 0 {
- count--
- var ch rune
- if chars == nil {
- ch = rune(getCryptoRandomInt(gap) + int64(start))
- } else {
- ch = chars[getCryptoRandomInt(gap)+int64(start)]
- }
- if letters && unicode.IsLetter(ch) || numbers && unicode.IsDigit(ch) || !letters && !numbers {
- if ch >= 56320 && ch <= 57343 { // low surrogate range
- if count == 0 {
- count++
- } else {
- // Insert low surrogate
- buffer[count] = ch
- count--
- // Insert high surrogate
- buffer[count] = rune(55296 + getCryptoRandomInt(128))
- }
- } else if ch >= 55296 && ch <= 56191 { // High surrogates range (Partial)
- if count == 0 {
- count++
- } else {
- // Insert low surrogate
- buffer[count] = rune(56320 + getCryptoRandomInt(128))
- count--
- // Insert high surrogate
- buffer[count] = ch
- }
- } else if ch >= 56192 && ch <= 56319 {
- // private high surrogate, skip it
- count++
- } else {
- // not one of the surrogates*
- buffer[count] = ch
- }
- } else {
- count++
- }
- }
- return string(buffer), nil
- }
- func getCryptoRandomInt(count int) int64 {
- nBig, err := rand.Int(rand.Reader, big.NewInt(int64(count)))
- if err != nil {
- panic(err)
- }
- return nBig.Int64()
- }
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