Golang (BEEGO) Verification Code Controller

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The core code is encapsulated by someone else's

The code is as follows:

/** * use) Register for routing * Beego. Router ("/yzm", &controllers. yzmcontroller{}, "Get:getyzm")//Verification code controller *beego. Router ("/yzm/judgeyzm", &controllers. yzmcontroller{}, "Post:judgeyzm")//Verification Code AJAX Verification * * 2) Usage *  */package controllersimport (crand" Crypto/rand "//" FMT "" Github.com/astaxie/beego "" github.com/ Astaxie/beego/session "" "Image" "Image/color" "image/png" "io" "Math/rand" "Net/http" "StrConv" "Time") var Globalsessions *session. Managerfunc init () {globalsessions, _ = session. Newmanager ("Memory", ' {"CookieName": "Gosessionid", "Enablesetcookie,omitempty": True, "gclifetime": 3600, " Maxlifetime ": 3600," secure ": false," Sessionidhashfunc ":" SHA1 "," Sessionidhashkey ":" "," Cookielifetime ": 3600," Providerconfig ":"} ') go Globalsessions.gc ()}type yzmcontroller struct {beego. controller}/** * Get Verification Code */func (this *yzmcontroller) Getyzm () {pic (this). Ctx.responsewriter, this. Ctx.request)}/** * Ajax Verification Code */func (this *yzmcontroller)Judgeyzm () {p: = this. GetString ("param") rs: = "Sorry, input" + p + "for error!" Sess: = Globalsessions.sessionstart (this. Ctx.responsewriter, this. ctx.request) if Sess. Get ("yzm") = = p {rs = "Y"///return y means correct}this. Ctx.writestring (RS)}const (stdwidth = 100stdHeight = 40maxSkew = 2) const (fontwidth = 5fontHeight = 8blackChar = 1) va R font = [][]byte{{//00, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0  0, 1, 1, 1, 0,},{/10, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1,},{//20, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1 , 1, 1, 1,},{//31, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1,  1, 1, 0,},{//41, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0,},{//51, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0,},{//60, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0,  0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0,},{//71, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0,},{//80, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0 , 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0,},{//90, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1,0, 0, 0, 0, 1,0, 0, 0, 0,, 1, 1, 1, 0,},}type Image struct {*image. Nrgbacolor *color. nrgbawidth int//a digit widthheight int//a digit heightdotsize int}func init () {rand. Seed (Int64 (time. Second))}func newimage (digits []byte, width, height int) *image {img: = new (image) R: = image. Rect (Img.width, Img.height, Stdwidth, Stdheight) img. Nrgba = image. Newnrgba (r) Img.color = &color. Nrgba{uint8 (Rand. INTN (129)), Uint8 (rand. INTN (129)), Uint8 (rand. INTN (129)), 0xff,}//Draw background (random circles of RAndom brightness) img.calculatesizes (width, height, len (digits)) Img.fillwithcircles (Ten, img.dotsize) Maxx: = width-(  img.width+img.dotsize) *len (digits)-Img.dotsizemaxy: = height-img.height-img.dotsize*2x: = Rnd (Img.dotsize*2, Maxx) y : = Rnd (img.dotsize*2, Maxy)//Draw Digits.for _, N: = range digits {img.drawdigit (font[n], x, y) x + = Img.width + img.dots ize}//Draw Strike-through Line.img.strikeThrough () return Img}func (img *image) writeto (w io. Writer) (Int64, error) {return 0, PNG. Encode (W, img)}func (img *image) calculatesizes (width, height, ncount int) {//Goal:fit all digits inside the Image.var b Order Intif width > Height {border = height/5} else {border = width/5}//Convert everything to floats for Calculati ONS.W: = Float64 (width-border*2)//268h: = Float64 (height-border*2)//48//FW takes into account 1-dot spacing Betwee N DIGITS.FW: = float64 (fontwidth) + 1//6FH: = Float64 (fontheight)//8nc: = Float64 (ncount)//7//Calculate the width of a single digit Taking into account only the//width of the IMAGE.NW: = W/nc//38//Calculate The height of a digit from this width.nh: = NW * FH/FW//51//Digit too high?if nh > H {//Fit digits based on height.nh = h//nh = 44NW = fw/fh * nh}//Calculat  E dot size.img.dotsize = Int (NH/FH)//Save Everything, making the actual width smaller by 1 dot-to-account//for spacing between digits.img.width = Int (NW) img.height = Int (NH)-Img.dotsize}func (img *image) fillwithcircles (n, Maxradius int) {color: = Img.colormaxx: = img. Bounds (). Max.xmaxy: = img. Bounds (). Max.yfor I: = 0; I < n; i++ {setrandombrightness (color, 255) R: = Rnd (1, Maxradius) img.drawcircle (color, Rnd (R, Maxx-r), Rnd (R, Maxy-r), R)}}func (img *image) drawhorizline (color color. Color, FromX, ToX, y int) {for x: = FromX; x <= ToX; Set (x, y, color)}}func (img *image) drawcircle (color color. Color, x, y, radius int) {f: = 1-radiusdfx: = 1dfy: =-2 * radiusxx: = 0yy: = radiusimg. Set (x, Y+radius, Color) img. Set (x, Y-radius, Color) img.drawhorizline (color, X-radius, X+radius, y) for xx < yy {if f >= 0 {yy--dfy + 2f + = dfy}xx++dfx + 2f + = DF Ximg.drawhorizline (color, x-xx, x+xx, y+yy) img.drawhorizline (color, x-xx, x+xx, y-yy) img.drawhorizline (color, x-yy, x+ YY, y+xx) img.drawhorizline (color, X-yy, X+yy, Y-XX)}}func (img *image) Strikethrough () {r: = 0maxx: = img. Bounds (). Max.xmaxy: = img. Bounds (). Max.yy: = Rnd (MAXY/3, MAXY-MAXY/3) for x: = 0; x < Maxx; X + = r {r = Rnd (1, img.dotsize/3) y + = rnd (-IMG.DOTSIZE/2, IMG.DOTSIZE/2) if y <= 0 | | y >= maxy {y = rnd (MAXY/3, Maxy -MAXY/3)}img.drawcircle (Img.color, x, Y, R)}}func (img *image) drawdigit (digit []byte, x, y int) {SKF: = rand. Float64 () * Float64 (Rnd (-maxskew, Maxskew)) xs: = float64 (x) Minr: = IMG.DOTSIZE/2//minumum RADIUSMAXR: = IMG.DOTSIZE/2 + IMG.DOTSIZE/4//maximum radiusy + rnd (-MINR, Minr) for yy: = 0; yy < Fontheight; yy++ {for XX: = 0; xx < fontwidth; xx++ {if digit[yy*fontwidth+xx]! = Blackchar {continue}//introduce Random variations.or: = Rnd (Minr, MAXR) Ox: = x + (XX * img.dotsize) + rnd (0, OR/2) Oy: = y + (yy * img.dotsize) + rnd (0, O R/2) img.drawcircle (Img.color, Ox, Oy, or)}xs + = SKFX = Int (xs)}}func setrandombrightness (c *color. Nrgba, Max Uint8) {minc: = min3 (C.R, C.G, c.b) Maxc: = Max3 (C.R, C.G, c.b) if MAXC > Max {return}n: = rand.  INTN (int (MAX-MAXC))-Int (minc) C.R = uint8 (int (C.R) + N) C.G = uint8 (int (C.G) + N) c.b = uint8 (int (C.B) + N)}func min3 (x, Y, Z uint8) (o uint8) {o = Xif y < o {o = y}if Z < o {o = Z}return}func max3 (x, y, z uint8) (o uint8) {o = xif y > o {o = y}if z > o {o = z}return}//rnd Returns a random number in range [From, To].func Rnd (from, to int) int {//printl N (to+1-from) return rand. INTN (To+1-from) + from}const (//Standard length of Uniuri string to achive ~95 bits of entropy. Stdlen = 16//Length of Uniurl string to achive ~119 bits of entropy, closest//to what can is losslessly converted to UUI DV4 (122 bits). Uuidlen = ()//standard characters allowed in UNIuri String.var stdchars = []byte ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")//New Returns a New random string of the standard length, consisting of//standard Characters.func New () string {return Newlenchars (Stdlen , stdchars)}//Newlen Returns a new random string of the provided length, consisting of//standard Characters.func Newlen ( length int) string {return Newlenchars (length, stdchars)}//Newlenchars Returns a new random string of the provided length , consisting//of the provided byte slice of allowed characters (maximum). Func newlenchars (length int, chars []byte) s Tring {b: = make ([]byte, length) R: = Yes ([]byte, length+ (LENGTH/4))//Storage for random Bytes.clen: = Byte (len (chars)) m AXRB: = Byte (chars)) I: = 0for {If _, err: = Io. Readfull (Crand. Reader, R); Err! = Nil {Panic ("Error reading from random Source:" + err.) Error ())}for _, c: = range R {if c >= maxrb {//Skip this number to avoid modulo bias.continue}b[i] = chars[c%clen]i++if i = = length {return string (b)}}}panic ("unreachable")}func pic (w http. Responsewriter, req *http. Request) {d: = make ([]byte, 4) S: = Newlen (4) SS: = "" D = []byte (s) for V: = range D {d[v]%= 10ss + = StrConv. Formatint (Int64 (D[v]),}w.header (). Set ("Content-type", "Image/png") Sess: = Globalsessions.sessionstart (W, req) defer Sess. Sessionrelease (W) sess. Delete ("Yzm") Sess. Set ("Yzm", ss)//fmt. Println ("-----------------------------------yzm:", Sess. Get ("Yzm")) NewImage (d, 100, 40). WriteTo (w)}func index (w http. Responsewriter, req *http. Request) {str: = "<meta charset=\" utf-8\ ">