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