fix rand.Intn painc

captcha_test.go

@@ -43,7 +43,7 @@ func TestCaptcha_GenerateB64s(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			c := NewCaptcha(tt.fields.Driver, tt.fields.Store)
-			gotId, b64s,_, err := c.Generate()
+			gotId, b64s, _, err := c.Generate()
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Captcha.Generate() error = %v, wantErr %v", err, tt.wantErr)
 				return
@@ -122,7 +122,7 @@ func TestCaptcha_Generate(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotId, gotB64s,_, err := tt.c.Generate()
+			gotId, gotB64s, _, err := tt.c.Generate()
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Captcha.Generate() error = %v, wantErr %v", err, tt.wantErr)
 				return

driver_chinese.go

@@ -2,13 +2,12 @@ package base64Captcha
 
 import (
 	"image/color"
-	"math/rand"
 	"strings"
 
 	"github.com/golang/freetype/truetype"
 )
 
-//DriverChinese is a driver of unicode Chinese characters.
+// DriverChinese is a driver of unicode Chinese characters.
 type DriverChinese struct {
 	//Height png height in pixel.
 	Height int
@@ -38,7 +37,7 @@ type DriverChinese struct {
 	fontsArray []*truetype.Font
 }
 
-//NewDriverChinese creates a driver of Chinese characters
+// NewDriverChinese creates a driver of Chinese characters
 func NewDriverChinese(height int, width int, noiseCount int, showLineOptions int, length int, source string, bgColor *color.RGBA, fontsStorage FontsStorage, fonts []string) *DriverChinese {
 	if fontsStorage == nil {
 		fontsStorage = DefaultEmbeddedFonts
@@ -57,7 +56,7 @@ func NewDriverChinese(height int, width int, noiseCount int, showLineOptions int
 	return &DriverChinese{Height: height, Width: width, NoiseCount: noiseCount, ShowLineOptions: showLineOptions, Length: length, Source: source, BgColor: bgColor, fontsStorage: fontsStorage, fontsArray: tfs}
 }
 
-//ConvertFonts loads fonts by names
+// ConvertFonts loads fonts by names
 func (d *DriverChinese) ConvertFonts() *DriverChinese {
 	if d.fontsStorage == nil {
 		d.fontsStorage = DefaultEmbeddedFonts
@@ -76,7 +75,7 @@ func (d *DriverChinese) ConvertFonts() *DriverChinese {
 	return d
 }
 
-//GenerateIdQuestionAnswer generates captcha content and its answer
+// GenerateIdQuestionAnswer generates captcha content and its answer
 func (d *DriverChinese) GenerateIdQuestionAnswer() (id, content, answer string) {
 	id = RandomId()
 
@@ -93,14 +92,14 @@ func (d *DriverChinese) GenerateIdQuestionAnswer() (id, content, answer string)
 
 	res := make([]string, d.Length)
 	for k := range res {
-		res[k] = ss[rand.Intn(length)]
+		res[k] = ss[randIntn(length)]
 	}
 
 	content = strings.Join(res, "")
 	return id, content, content
 }
 
-//DrawCaptcha generates captcha item(image)
+// DrawCaptcha generates captcha item(image)
 func (d *DriverChinese) DrawCaptcha(content string) (item Item, err error) {
 
 	var bgc color.RGBA

driver_digit.go

@@ -71,8 +71,8 @@ func (d *DriverDigit) DrawCaptcha(content string) (item Item, err error) {
 	} else {
 		border = d.Width / 5
 	}
-	x := rand.Intn(maxx-border*2) + border
-	y := rand.Intn(maxy-border*2) + border
+	x := randIntn(maxx-border*2) + border
+	y := randIntn(maxy-border*2) + border
 	// Draw digits.
 	for _, n := range digits {
 		itemDigit.drawDigit(digitFontData[n], x, y)

driver_language.go

@@ -3,12 +3,11 @@ package base64Captcha
 import (
 	"image/color"
 	"log"
-	"math/rand"
 
 	"github.com/golang/freetype/truetype"
 )
 
-//https://en.wikipedia.org/wiki/Unicode_block
+// https://en.wikipedia.org/wiki/Unicode_block
 var langMap = map[string][]int{
 	//"zh-CN": []int{19968, 40869},
 	"latin":  {0x0000, 0x007f},
@@ -33,13 +32,13 @@ func generateRandomRune(size int, code string) string {
 	end := lang[1]
 	randRune := make([]rune, size)
 	for i := range randRune {
-		idx := rand.Intn(end-start) + start
+		idx := randIntn(end-start) + start
 		randRune[i] = rune(idx)
 	}
 	return string(randRune)
 }
 
-//DriverLanguage generates language unicode by lanuage
+// DriverLanguage generates language unicode by lanuage
 type DriverLanguage struct {
 	// Height png height in pixel.
 	Height int
@@ -66,19 +65,19 @@ type DriverLanguage struct {
 	LanguageCode string
 }
 
-//NewDriverLanguage creates a driver
+// NewDriverLanguage creates a driver
 func NewDriverLanguage(height int, width int, noiseCount int, showLineOptions int, length int, bgColor *color.RGBA, fontsStorage FontsStorage, fonts []*truetype.Font, languageCode string) *DriverLanguage {
 	return &DriverLanguage{Height: height, Width: width, NoiseCount: noiseCount, ShowLineOptions: showLineOptions, Length: length, BgColor: bgColor, fontsStorage: fontsStorage, Fonts: fonts, LanguageCode: languageCode}
 }
 
-//GenerateIdQuestionAnswer creates content and answer
+// GenerateIdQuestionAnswer creates content and answer
 func (d *DriverLanguage) GenerateIdQuestionAnswer() (id, content, answer string) {
 	id = RandomId()
 	content = generateRandomRune(d.Length, d.LanguageCode)
 	return id, content, content
 }
 
-//DrawCaptcha creates item
+// DrawCaptcha creates item
 func (d *DriverLanguage) DrawCaptcha(content string) (item Item, err error) {
 	var bgc color.RGBA
 	if d.BgColor != nil {

fonts.go

@@ -1,8 +1,6 @@
 package base64Captcha
 
 import (
-	"math/rand"
-
 	"github.com/golang/freetype/truetype"
 )
 
@@ -18,11 +16,11 @@ var fontsSimple = DefaultEmbeddedFonts.LoadFontsByNames([]string{
 	"fonts/chromohv.ttf",
 })
 
-//var fontemoji = loadFontByName("fonts/seguiemj.ttf")
+// var fontemoji = loadFontByName("fonts/seguiemj.ttf")
 var fontsAll = append(fontsSimple, fontChinese)
 var fontChinese = DefaultEmbeddedFonts.LoadFontByName("fonts/wqy-microhei.ttc")
 
-//randFontFrom choose random font family.选择随机的字体
+// randFontFrom choose random font family.选择随机的字体
 func randFontFrom(fonts []*truetype.Font) *truetype.Font {
 	fontCount := len(fonts)
 
@@ -31,7 +29,7 @@ func randFontFrom(fonts []*truetype.Font) *truetype.Font {
 		fonts = fontsAll
 		fontCount = len(fontsAll)
 	}
-	index := rand.Intn(fontCount)
+	index := randIntn(fontCount)
 	return fonts[index]
 }
 

item_audio.go

@@ -13,7 +13,7 @@ import (
 	"math/rand"
 )
 
-//ItemAudio captcha-audio-engine return type.
+// ItemAudio captcha-audio-engine return type.
 type ItemAudio struct {
 	answer      string
 	body        *bytes.Buffer
@@ -81,7 +81,7 @@ func (a *ItemAudio) makeBackgroundSound(length int) []byte {
 	for i := 0; i < length/(sampleRate/10); i++ {
 		snd := reversedSound(a.digitSounds[rand.Intn(10)])
 		//snd = changeSpeed(snd, a.rng.Float(0.8, 1.2))
-		place := rand.Intn(len(b) - len(snd))
+		place := randIntn(len(b) - len(snd))
 		setSoundLevel(snd, randFloat64Range(0.04, 0.08))
 		mixSound(b[place:], snd)
 	}

item_char.go

@@ -5,9 +5,6 @@ import (
 	"encoding/base64"
 	"errors"
 	"fmt"
-	"github.com/golang/freetype"
-	"github.com/golang/freetype/truetype"
-	"golang.org/x/image/font"
 	"image"
 	"image/color"
 	"image/draw"
@@ -16,17 +13,21 @@ import (
 	"log"
 	"math"
 	"math/rand"
+
+	"github.com/golang/freetype"
+	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/font"
 )
 
-//ItemChar captcha item of unicode characters
+// ItemChar captcha item of unicode characters
 type ItemChar struct {
 	bgColor color.Color
 	width   int
 	height  int
 	nrgba   *image.NRGBA
 }
 
-//NewItemChar creates a captcha item of characters
+// NewItemChar creates a captcha item of characters
 func NewItemChar(w int, h int, bgColor color.RGBA) *ItemChar {
 	d := ItemChar{width: w, height: h}
 	m := image.NewNRGBA(image.Rect(0, 0, w, h))
@@ -35,18 +36,18 @@ func NewItemChar(w int, h int, bgColor color.RGBA) *ItemChar {
 	return &d
 }
 
-//drawHollowLine draw strong and bold white line.
+// drawHollowLine draw strong and bold white line.
 func (item *ItemChar) drawHollowLine() *ItemChar {
 
 	first := item.width / 20
 	end := first * 19
 
 	lineColor := RandLightColor()
 
-	x1 := float64(rand.Intn(first))
-	//y1 := float64(rand.Intn(y)+y);
+	x1 := float64(randIntn(first))
+	//y1 := float64(randIntn(y)+y);
 
-	x2 := float64(rand.Intn(first) + end)
+	x2 := float64(randIntn(first) + end)
 
 	multiple := float64(rand.Intn(5)+3) / float64(5)
 	if int(multiple*10)%3 == 0 {
@@ -72,12 +73,12 @@ func (item *ItemChar) drawHollowLine() *ItemChar {
 	return item
 }
 
-//drawSineLine draw a sine line.
+// drawSineLine draw a sine line.
 func (item *ItemChar) drawSineLine() *ItemChar {
 	var py float64
 
 	//振幅
-	a := rand.Intn(item.height / 2)
+	a := randIntn(item.height / 2)
 
 	//Y轴方向偏移量
 	b := random(int64(-item.height/4), int64(item.height/4))
@@ -116,7 +117,7 @@ func (item *ItemChar) drawSineLine() *ItemChar {
 	return item
 }
 
-//drawSlimLine draw n slim-random-color lines.
+// drawSlimLine draw n slim-random-color lines.
 func (item *ItemChar) drawSlimLine(num int) *ItemChar {
 
 	first := item.width / 10
@@ -126,15 +127,15 @@ func (item *ItemChar) drawSlimLine(num int) *ItemChar {
 
 	for i := 0; i < num; i++ {
 
-		point1 := point{X: rand.Intn(first), Y: rand.Intn(y)}
-		point2 := point{X: rand.Intn(first) + end, Y: rand.Intn(y)}
+		point1 := point{X: randIntn(first), Y: randIntn(y)}
+		point2 := point{X: randIntn(first) + end, Y: randIntn(y)}
 
 		if i%2 == 0 {
-			point1.Y = rand.Intn(y) + y*2
-			point2.Y = rand.Intn(y)
+			point1.Y = randIntn(y) + y*2
+			point2.Y = randIntn(y)
 		} else {
-			point1.Y = rand.Intn(y) + y*(i%2)
-			point2.Y = rand.Intn(y) + y*2
+			point1.Y = randIntn(y) + y*(i%2)
+			point2.Y = randIntn(y) + y*2
 		}
 
 		item.drawBeeline(point1, point2, RandDeepColor())
@@ -187,8 +188,8 @@ func (item *ItemChar) drawNoise(noiseText string, fonts []*truetype.Font) error
 	rawFontSize := float64(item.height) / (1 + float64(rand.Intn(7))/float64(10))
 
 	for _, char := range noiseText {
-		rw := rand.Intn(item.width)
-		rh := rand.Intn(item.height)
+		rw := randIntn(item.width)
+		rh := randIntn(item.height)
 		fontSize := rawFontSize/2 + float64(rand.Intn(5))
 		c.SetSrc(image.NewUniform(RandLightColor()))
 		c.SetFontSize(fontSize)
@@ -222,7 +223,7 @@ func (item *ItemChar) drawText(text string, fonts []*truetype.Font) error {
 		c.SetFontSize(float64(fontSize))
 		c.SetFont(randFontFrom(fonts))
 		x := fontWidth*i + fontWidth/fontSize
-		y := item.height/2 + fontSize/2 - rand.Intn(item.height/16*3)
+		y := item.height/2 + fontSize/2 - randIntn(item.height/16*3)
 		pt := freetype.Pt(x, y)
 		if _, err := c.DrawString(string(s), pt); err != nil {
 			return err
@@ -231,7 +232,7 @@ func (item *ItemChar) drawText(text string, fonts []*truetype.Font) error {
 	return nil
 }
 
-//BinaryEncoding encodes an image to PNG and returns a byte slice.
+// BinaryEncoding encodes an image to PNG and returns a byte slice.
 func (item *ItemChar) BinaryEncoding() []byte {
 	var buf bytes.Buffer
 	if err := png.Encode(&buf, item.nrgba); err != nil {

item_digit.go

@@ -29,7 +29,7 @@ type ItemDigit struct {
 	//rng      siprng
 }
 
-//NewItemDigit create a instance of item-digit
+// NewItemDigit create a instance of item-digit
 func NewItemDigit(width int, height int, dotCount int, maxSkew float64) *ItemDigit {
 	itemDigit := &ItemDigit{width: width, height: height, dotCount: dotCount, maxSkew: maxSkew}
 	//init image.Paletted
@@ -157,13 +157,13 @@ func (m *ItemDigit) strikeThrough() {
 		yo := amplitude * math.Sin(float64(x)*dx)
 		for yn := 0; yn < m.dotSize; yn++ {
 			//r := m.rng.Int(0, m.dotSize)
-			r := rand.Intn(m.dotSize)
+			r := randIntn(m.dotSize)
 			m.drawCircle(x+int(xo), y+int(yo)+(yn*m.dotSize), r/2, 1)
 		}
 	}
 }
 
-//draw digit
+// draw digit
 func (m *ItemDigit) drawDigit(digit []byte, x, y int) {
 	skf := randFloat64Range(-m.maxSkew, m.maxSkew)
 	xs := float64(x)
@@ -205,7 +205,7 @@ func randomBrightness(c color.RGBA, max uint8) color.RGBA {
 	if maxc > max {
 		return c
 	}
-	n := rand.Intn(int(max-maxc)) - int(minc)
+	n := randIntn(int(max-maxc)) - int(minc)
 	return color.RGBA{
 		uint8(int(c.R) + n),
 		uint8(int(c.G) + n),

randIntn.go

@@ -0,0 +1,10 @@
+package base64Captcha
+
+import "math/rand"
+
+func randIntn(n int) int {
+	if n > 0 {
+		return rand.Intn(n)
+	}
+	return 0
+}