Refactor CSRF protector (#32057)

Remove unused CSRF options, decouple "new csrf protector" and "prepare"
logic, do not redirect to home page if CSRF validation falis (it
shouldn't happen in daily usage, if it happens, redirecting to home
doesn't help either but just makes the problem more complex for "fetch")

services/context/context.go

@@ -138,10 +138,8 @@ func Contexter() func(next http.Handler) http.Handler {
 	csrfOpts := CsrfOptions{
 		Secret:         hex.EncodeToString(setting.GetGeneralTokenSigningSecret()),
 		Cookie:         setting.CSRFCookieName,
-		SetCookie:      true,
 		Secure:         setting.SessionConfig.Secure,
 		CookieHTTPOnly: setting.CSRFCookieHTTPOnly,
-		Header:         "X-Csrf-Token",
 		CookieDomain:   setting.SessionConfig.Domain,
 		CookiePath:     setting.SessionConfig.CookiePath,
 		SameSite:       setting.SessionConfig.SameSite,
@@ -167,7 +165,7 @@ func Contexter() func(next http.Handler) http.Handler {
 			ctx.Base.AppendContextValue(WebContextKey, ctx)
 			ctx.Base.AppendContextValueFunc(gitrepo.RepositoryContextKey, func() any { return ctx.Repo.GitRepo })
 
-			ctx.Csrf = PrepareCSRFProtector(csrfOpts, ctx)
+			ctx.Csrf = NewCSRFProtector(csrfOpts)
 
 			// Get the last flash message from cookie
 			lastFlashCookie := middleware.GetSiteCookie(ctx.Req, CookieNameFlash)
@@ -204,8 +202,6 @@ func Contexter() func(next http.Handler) http.Handler {
 			ctx.Resp.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)
 
 			ctx.Data["SystemConfig"] = setting.Config()
-			ctx.Data["CsrfToken"] = ctx.Csrf.GetToken()
-			ctx.Data["CsrfTokenHtml"] = template.HTML(`<input type="hidden" name="_csrf" value="` + ctx.Data["CsrfToken"].(string) + `">`)
 
 			// FIXME: do we really always need these setting? There should be someway to have to avoid having to always set these
 			ctx.Data["DisableMigrations"] = setting.Repository.DisableMigrations