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"
"time"
"github.com/dchest/captcha"
"go.goblog.app/app/pkgs/contenttype"
)
const captchaSolvedKey contextKey = "captchaSolved"
var captchaStore = captcha.NewMemoryStore(100, 10*time.Minute)
func init() {
captcha.SetCustomStore(captchaStore)
}
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 session
ses, err := a.captchaSessions.Get(r, "c")
if err != nil {
a.serveError(w, r, err.Error(), http.StatusInternalServerError)
return
}
if captcha, ok := ses.Values["captcha"]; ok && captcha == true {
// Captcha already solved
next.ServeHTTP(w, r.WithContext(context.WithValue(r.Context(), captchaSolvedKey, true)))
return
}
// Get captcha ID
captchaId := ""
if sesCaptchaId, ok := ses.Values["captchaid"]; ok {
// Already has a captcha ID
ci := sesCaptchaId.(string)
if captcha.Reload(ci) {
captchaId = ci
}
}
if captchaId == "" {
captchaId = captcha.New()
ses.Values["captchaid"] = captchaId
}
// Encode original request
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())
}
// Render captcha
_ = ses.Save(r, w)
w.Header().Set("Cache-Control", "no-store,max-age=0")
a.renderWithStatusCode(w, r, http.StatusUnauthorized, templateCaptcha, &renderData{
Data: map[string]string{
"captchamethod": r.Method,
"captchaheaders": base64.StdEncoding.EncodeToString(h),
"captchabody": base64.StdEncoding.EncodeToString(b),
"captchaid": captchaId,
},
})
})
}
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
}
// Decode and prepare original request
captchabody, _ := base64.StdEncoding.DecodeString(r.FormValue("captchabody"))
origReq, _ := 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 {
origReq.Header[k] = v
}
// Get session
ses, err := a.captchaSessions.Get(r, "c")
if err != nil {
a.serveError(w, r, err.Error(), http.StatusInternalServerError)
return true
}
// Check if session contains a captchaId and if captcha is solved
if sesCaptchaId, ok := ses.Values["captchaid"]; ok && captcha.VerifyString(sesCaptchaId.(string), r.FormValue("digits")) {
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
}
origReq = origReq.WithContext(context.WithValue(origReq.Context(), captchaSolvedKey, true))
}
// Copy captcha cookie to original request
if captchaCookie, err := r.Cookie("c"); err == nil {
origReq.AddCookie(captchaCookie)
}
// Serve original request
a.d.ServeHTTP(w, origReq)
return true
}