From fb3637df9553acd391710ae442d34455a4f6ff0d Mon Sep 17 00:00:00 2001 From: Xe Iaso Date: Tue, 16 Sep 2025 17:32:13 -0400 Subject: [PATCH] feat(metarefresh): randomly use the Refresh header (#1133) * feat(lib/challenge): expose ResponseWriter to challenge issuers Signed-off-by: Xe Iaso * feat(metarefresh): randomly use the Refresh header There are several ways to trigger an automatic refresh without JavaScript. One of them is the "meta refresh" method[1], but the other is with the Refresh header[2]. Both are semantically identical and supported with browsers as old as Chrome version 1. Given that they are basically the same thing, this patch makes Anubis randomly select between them by using the challenge random data's first character. This will fire about 50% of the time. I expect this to have no impact. If this works out fine, then I will implement some kind of fallback logic for the fast challenge such that admins can opt into allowing clients with a no-js configuration to pass the fast challenge. This needs to bake in the oven though. [1]: https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/meta/http-equiv [2]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Refresh Signed-off-by: Xe Iaso * docs: update CHANGELOG Signed-off-by: Xe Iaso * feat(metarefresh): simplify random logic Signed-off-by: Xe Iaso --------- Signed-off-by: Xe Iaso Signed-off-by: Xe Iaso --- docs/docs/CHANGELOG.md | 1 + lib/challenge/interface.go | 2 +- lib/challenge/metarefresh/metarefresh.go | 10 ++++-- lib/challenge/metarefresh/metarefresh.templ | 6 ++-- .../metarefresh/metarefresh_templ.go | 32 ++++++++++++------- lib/challenge/preact/preact.go | 2 +- lib/challenge/proofofwork/proofofwork.go | 2 +- lib/challenge/proofofwork/proofofwork_test.go | 3 +- lib/http.go | 28 ++++++++-------- 9 files changed, 53 insertions(+), 33 deletions(-) diff --git a/docs/docs/CHANGELOG.md b/docs/docs/CHANGELOG.md index e503a78..8b2c9aa 100644 --- a/docs/docs/CHANGELOG.md +++ b/docs/docs/CHANGELOG.md @@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0 - Add the `DIFFICULTY_IN_JWT` option, which allows one to add the `difficulty` field in the JWT claims which indicates the difficulty of the token ([#1063](https://github.com/TecharoHQ/anubis/pull/1063)). - Ported the client-side JS to TypeScript to avoid egregious errors in the future. - Fixes concurrency problems with very old browsers ([#1082](https://github.com/TecharoHQ/anubis/issues/1082)). +- Randomly use the Refresh header instead of the meta refresh tag in the metarefresh challenge. - Update OpenRC service to truncate the runtime directory before starting Anubis. ### Bug Fixes diff --git a/lib/challenge/interface.go b/lib/challenge/interface.go index 963d6ca..c7a1944 100644 --- a/lib/challenge/interface.go +++ b/lib/challenge/interface.go @@ -61,7 +61,7 @@ type Impl interface { Setup(mux *http.ServeMux) // Issue a new challenge to the user, called by the Anubis. - Issue(r *http.Request, lg *slog.Logger, in *IssueInput) (templ.Component, error) + Issue(w http.ResponseWriter, r *http.Request, lg *slog.Logger, in *IssueInput) (templ.Component, error) // Validate a challenge, making sure that it passes muster. Validate(r *http.Request, lg *slog.Logger, in *ValidateInput) error diff --git a/lib/challenge/metarefresh/metarefresh.go b/lib/challenge/metarefresh/metarefresh.go index 75ac70f..c554b91 100644 --- a/lib/challenge/metarefresh/metarefresh.go +++ b/lib/challenge/metarefresh/metarefresh.go @@ -23,7 +23,7 @@ type Impl struct{} func (i *Impl) Setup(mux *http.ServeMux) {} -func (i *Impl) Issue(r *http.Request, lg *slog.Logger, in *challenge.IssueInput) (templ.Component, error) { +func (i *Impl) Issue(w http.ResponseWriter, r *http.Request, lg *slog.Logger, in *challenge.IssueInput) (templ.Component, error) { u, err := r.URL.Parse(anubis.BasePrefix + "/.within.website/x/cmd/anubis/api/pass-challenge") if err != nil { return nil, fmt.Errorf("can't render page: %w", err) @@ -35,9 +35,15 @@ func (i *Impl) Issue(r *http.Request, lg *slog.Logger, in *challenge.IssueInput) q.Set("id", in.Challenge.ID) u.RawQuery = q.Encode() + showMeta := in.Challenge.RandomData[0]%2 == 0 + + if !showMeta { + w.Header().Add("Refresh", fmt.Sprintf("%d; url=%s", in.Rule.Challenge.Difficulty+1, u.String())) + } + loc := localization.GetLocalizer(r) - result := page(u.String(), in.Rule.Challenge.Difficulty, loc) + result := page(u.String(), in.Rule.Challenge.Difficulty, showMeta, loc) return result, nil } diff --git a/lib/challenge/metarefresh/metarefresh.templ b/lib/challenge/metarefresh/metarefresh.templ index dccf765..c074f59 100644 --- a/lib/challenge/metarefresh/metarefresh.templ +++ b/lib/challenge/metarefresh/metarefresh.templ @@ -7,12 +7,14 @@ import ( "github.com/TecharoHQ/anubis/lib/localization" ) -templ page(redir string, difficulty int, loc *localization.SimpleLocalizer) { +templ page(redir string, difficulty int, showMeta bool, loc *localization.SimpleLocalizer) {
{ loc.T("loading") }

{ loc.T("connection_security") }

- + if showMeta { + + }
} diff --git a/lib/challenge/metarefresh/metarefresh_templ.go b/lib/challenge/metarefresh/metarefresh_templ.go index 048260b..f54c45a 100644 --- a/lib/challenge/metarefresh/metarefresh_templ.go +++ b/lib/challenge/metarefresh/metarefresh_templ.go @@ -15,7 +15,7 @@ import ( "github.com/TecharoHQ/anubis/lib/localization" ) -func page(redir string, difficulty int, loc *localization.SimpleLocalizer) templ.Component { +func page(redir string, difficulty int, showMeta bool, loc *localization.SimpleLocalizer) templ.Component { return templruntime.GeneratedTemplate(func(templ_7745c5c3_Input templruntime.GeneratedComponentInput) (templ_7745c5c3_Err error) { templ_7745c5c3_W, ctx := templ_7745c5c3_Input.Writer, templ_7745c5c3_Input.Context if templ_7745c5c3_CtxErr := ctx.Err(); templ_7745c5c3_CtxErr != nil { @@ -88,20 +88,30 @@ func page(redir string, difficulty int, loc *localization.SimpleLocalizer) templ if templ_7745c5c3_Err != nil { return templ_7745c5c3_Err } - templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 5, "

") if templ_7745c5c3_Err != nil { return templ_7745c5c3_Err } - var templ_7745c5c3_Var6 string - templ_7745c5c3_Var6, templ_7745c5c3_Err = templ.JoinStringErrs(fmt.Sprintf("%d; url=%s", difficulty+1, redir)) - if templ_7745c5c3_Err != nil { - return templ.Error{Err: templ_7745c5c3_Err, FileName: `metarefresh.templ`, Line: 16, Col: 85} + if showMeta { + templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 6, "") + if templ_7745c5c3_Err != nil { + return templ_7745c5c3_Err + } } - _, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var6)) - if templ_7745c5c3_Err != nil { - return templ_7745c5c3_Err - } - templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 6, "\">") + templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 8, "") if templ_7745c5c3_Err != nil { return templ_7745c5c3_Err } diff --git a/lib/challenge/preact/preact.go b/lib/challenge/preact/preact.go index 0276d7d..a785f98 100644 --- a/lib/challenge/preact/preact.go +++ b/lib/challenge/preact/preact.go @@ -38,7 +38,7 @@ type impl struct{} func (i *impl) Setup(mux *http.ServeMux) {} -func (i *impl) Issue(r *http.Request, lg *slog.Logger, in *challenge.IssueInput) (templ.Component, error) { +func (i *impl) Issue(w http.ResponseWriter, r *http.Request, lg *slog.Logger, in *challenge.IssueInput) (templ.Component, error) { u, err := r.URL.Parse(anubis.BasePrefix + "/.within.website/x/cmd/anubis/api/pass-challenge") if err != nil { return nil, fmt.Errorf("can't render page: %w", err) diff --git a/lib/challenge/proofofwork/proofofwork.go b/lib/challenge/proofofwork/proofofwork.go index 8cd3127..b9be014 100644 --- a/lib/challenge/proofofwork/proofofwork.go +++ b/lib/challenge/proofofwork/proofofwork.go @@ -27,7 +27,7 @@ type Impl struct { func (i *Impl) Setup(mux *http.ServeMux) {} -func (i *Impl) Issue(r *http.Request, lg *slog.Logger, in *chall.IssueInput) (templ.Component, error) { +func (i *Impl) Issue(w http.ResponseWriter, r *http.Request, lg *slog.Logger, in *chall.IssueInput) (templ.Component, error) { loc := localization.GetLocalizer(r) return page(loc), nil } diff --git a/lib/challenge/proofofwork/proofofwork_test.go b/lib/challenge/proofofwork/proofofwork_test.go index 4e71bcf..c0611a5 100644 --- a/lib/challenge/proofofwork/proofofwork_test.go +++ b/lib/challenge/proofofwork/proofofwork_test.go @@ -4,6 +4,7 @@ import ( "errors" "log/slog" "net/http" + "net/http/httptest" "testing" "github.com/TecharoHQ/anubis/lib/challenge" @@ -133,7 +134,7 @@ func TestBasic(t *testing.T) { }, } - if _, err := i.Issue(cs.req, lg, inp); err != nil { + if _, err := i.Issue(httptest.NewRecorder(), cs.req, lg, inp); err != nil { t.Errorf("can't issue challenge: %v", err) } diff --git a/lib/http.go b/lib/http.go index 7209d58..1332035 100644 --- a/lib/http.go +++ b/lib/http.go @@ -29,19 +29,19 @@ var domainMatchRegexp = regexp.MustCompile(`^((xn--)?[a-z0-9]+(-[a-z0-9]+)*\.)+[ // internal glob matcher. Matching is case-insensitive on hostnames. func matchRedirectDomain(allowed []string, host string) bool { h := strings.ToLower(strings.TrimSpace(host)) - for _, pat := range allowed { - p := strings.ToLower(strings.TrimSpace(pat)) - if strings.Contains(p, glob.GLOB) { - if glob.Glob(p, h) { - return true - } - continue - } - if p == h { - return true - } - } - return false + for _, pat := range allowed { + p := strings.ToLower(strings.TrimSpace(pat)) + if strings.Contains(p, glob.GLOB) { + if glob.Glob(p, h) { + return true + } + continue + } + if p == h { + return true + } + } + return false } type CookieOpts struct { @@ -214,7 +214,7 @@ func (s *Server) RenderIndex(w http.ResponseWriter, r *http.Request, cr policy.C Store: s.store, } - component, err := impl.Issue(r, lg, in) + component, err := impl.Issue(w, r, lg, in) if err != nil { lg.Error("[unexpected] challenge component render failed, please open an issue", "err", err) // This is likely a bug in the template. Should never be triggered as CI tests for this. s.respondWithError(w, r, fmt.Sprintf("%s \"RenderIndex\"", localizer.T("internal_server_error")))