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package base64Captcha
import (
"crypto/rand"
"fmt"
"io"
"os"
"path/filepath"
)
//parseDigitsToString parse randomDigits to normal string
func parseDigitsToString(bytes []byte) string {
stringB := make([]byte, len(bytes))
for idx, by := range bytes {
stringB[idx] = by + '0'
}
return string(stringB)
}
func stringToFakeByte(content string) []byte {
digits := make([]byte, len(content))
for idx, cc := range content {
digits[idx] = byte(cc - '0')
}
return digits
}
// randomDigits returns a byte slice of the given length containing
// pseudorandom numbers in range 0-9. The slice can be used as a captcha
// solution.
func randomDigits(length int) []byte {
return randomBytesMod(length, 10)
}
// randomBytes returns a byte slice of the given length read from CSPRNG.
func randomBytes(length int) (b []byte) {
b = make([]byte, length)
if _, err := io.ReadFull(rand.Reader, b); err != nil {
panic("captcha: error reading random source: " + err.Error())
}
return
}
// randomBytesMod returns a byte slice of the given length, where each byte is
// a random number modulo mod.
func randomBytesMod(length int, mod byte) (b []byte) {
if length == 0 {
return nil
}
if mod == 0 {
panic("captcha: bad mod argument for randomBytesMod")
}
maxrb := 255 - byte(256%int(mod))
b = make([]byte, length)
i := 0
for {
r := randomBytes(length + (length / 4))
for _, c := range r {
if c > maxrb {
// Skip this number to avoid modulo bias.
continue
}
b[i] = c % mod
i++
if i == length {
return
}
}
}
}
func itemWriteFile(cap Item, outputDir, fileName, fileExt string) error {
filePath := filepath.Join(outputDir, fileName+"."+fileExt)
if !pathExists(outputDir) {
_ = os.MkdirAll(outputDir, os.ModePerm)
}
file, err := os.Create(filePath)
if err != nil {
fmt.Printf("%s is invalid path.error:%v", filePath, err)
return err
}
defer file.Close()
_, err = cap.WriteTo(file)
return err
}
func pathExists(path string) bool {
_, err := os.Stat(path)
if err == nil {
return true
}
if os.IsNotExist(err) {
return false
}
return false
}