Simple blogging system written in Go https://goblog.app
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package main
import (
"bytes"
"context"
"encoding/base64"
"encoding/json"
"io"
"net/http"
"strings"
"github.com/dchest/captcha"
"go.goblog.app/app/pkgs/contenttype"
)
const captchaSolvedKey contextKey = "captchaSolved"
func (a *goBlog) captchaMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Check if captcha already solved
if solved, ok := r.Context().Value(captchaSolvedKey).(bool); ok && solved {
next.ServeHTTP(w, r)
return
}
// Check Cookie
ses, err := a.captchaSessions.Get(r, "c")
if err == nil && ses != nil {
if captcha, ok := ses.Values["captcha"]; ok && captcha.(bool) {
next.ServeHTTP(w, r.WithContext(context.WithValue(r.Context(), captchaSolvedKey, true)))
return
}
}
// Show Captcha
w.Header().Set("Cache-Control", "no-store,max-age=0")
h, _ := json.Marshal(r.Header)
b, _ := io.ReadAll(io.LimitReader(r.Body, 20*1000*1000)) // Only allow 20 MB
_ = r.Body.Close()
if len(b) == 0 {
// Maybe it's a form
_ = r.ParseForm()
b = []byte(r.PostForm.Encode())
}
a.renderWithStatusCode(w, r, http.StatusUnauthorized, templateCaptcha, &renderData{
BlogString: r.Context().Value(blogKey).(string),
Data: map[string]string{
"captchamethod": r.Method,
"captchaheaders": base64.StdEncoding.EncodeToString(h),
"captchabody": base64.StdEncoding.EncodeToString(b),
"captchaid": captcha.New(),
},
})
})
}
func (a *goBlog) checkIsCaptcha(next http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
if !a.checkCaptcha(rw, r) {
next.ServeHTTP(rw, r)
}
})
}
func (a *goBlog) checkCaptcha(w http.ResponseWriter, r *http.Request) bool {
if r.Method != http.MethodPost {
return false
}
if !strings.Contains(r.Header.Get(contentType), contenttype.WWWForm) {
return false
}
if r.FormValue("captchaaction") != "captcha" {
return false
}
// Prepare original request
captchabody, _ := base64.StdEncoding.DecodeString(r.FormValue("captchabody"))
req, _ := http.NewRequest(r.FormValue("captchamethod"), r.RequestURI, bytes.NewReader(captchabody))
// Copy original headers
captchaheaders, _ := base64.StdEncoding.DecodeString(r.FormValue("captchaheaders"))
var headers http.Header
_ = json.Unmarshal(captchaheaders, &headers)
for k, v := range headers {
req.Header[k] = v
}
// Check captcha and create cookie
if captcha.VerifyString(r.FormValue("captchaid"), r.FormValue("digits")) {
ses, err := a.captchaSessions.Get(r, "c")
if err != nil {
a.serveError(w, r, err.Error(), http.StatusInternalServerError)
return true
}
ses.Values["captcha"] = true
err = a.captchaSessions.Save(r, w, ses)
if err != nil {
a.serveError(w, r, err.Error(), http.StatusInternalServerError)
return true
}
req = req.WithContext(context.WithValue(req.Context(), captchaSolvedKey, true))
}
// Serve original request
a.d.ServeHTTP(w, req)
return true
}