How to use captchae in my login form in GO?

Getting Help
1

I want to use captchae in my login form in my login page. I am using “github.com/afocus/captcha”. and the following code for this purpose:

func captchae(w http.ResponseWriter, req *http.Request) {
pd := captcha.New{
// Must set a font, Other settings have default values
cap.SetFont(“comic.ttf”)
img str := cap.Create(4, captcha.NUM)
}
err := tpl.ExecuteTemplate(w, “admin.gohtml”, pd)
if err != nil {
log.Println(err)
http.Error(w, “Internal server error”, http.StatusInternalServerError)
return
}
}
But it is throwing some error. Can you please suggest me what is the correct way of using captchae in my login page.

Thanks
Deepak

2

What is the error?

3

Sorry for being late in reply. The error coming is as following:-

go build main.go

command-line-arguments

.\main.go:84: syntax error: unexpected semicolon or newline, expecting comma or
}

My function for Captcha is as following:-

func captchae(w http.ResponseWriter, req *http.Request) {

pd := captcha.New{
 //Must set a font, Other settings have default values
cap.SetFont("comic.ttf")
img str := cap.Create(4, captcha.NUM)
}
err := tpl.ExecuteTemplate(w, "admin.gohtml", pd)
if err != nil {
	log.Println(err)
	http.Error(w, "Internal server error", http.StatusInternalServerError)
	return
}

}

4

I think this is what you intended:

func captchae(w http.ResponseWriter, req *http.Request) {
	pd := captcha.New()
	//Must set a font, Other settings have default values
	pd.SetFont("comic.ttf")
	img, str := pd.Create(4, captcha.NUM)

	err := tpl.ExecuteTemplate(w, "admin.gohtml", pd)
	if err != nil {
		log.Println(err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
}
  • captcha.New is a function, not a struct literal as what you wrote seems to indicate. It takes no arguments
  • since you called your captca pd, I renamed the references to cap
  • cap.Create returns two values. They require a comma to separate them
5

Thanks a lot for the reply. After making the changes that you have suggested like this:-

func captchae(w http.ResponseWriter, req *http.Request) {
pd := captcha.New()
 //Must set a font, Other settings have default values
pd.SetFont("comic.ttf")
img, str := pd.Create(4, captcha.NUM)

err := tpl.ExecuteTemplate(w, "admin.gohtml", pd)
if err != nil {
	log.Println(err)
	http.Error(w, "Internal server error", http.StatusInternalServerError)
	return
}  }

It is giving this error now:-

go build main.go

command-line-arguments

.\main.go:85: img declared and not used
.\main.go:85: str declared and not used

6

because you just declared the variables but not using them anywhere

7

You might want to look at the example code: https://github.com/afocus/captcha/blob/master/examples/main.go

Sadly that example isn’t a complete solution because it doesn’t do everything. My quick thoughts on what a captcha flow requires:

  1. generate the text and image; server remembers the text, sends image to browser
  2. browser displays image
  3. user fills in what the text is; POSTs to server
  4. server compares what the user thinks the text is with the remembered text
  5. goto 1 if incorrect, proceed if correct

Both your code and the example code don’t do all of this.

8

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