Commit `48a4e98ae7`

48a4e98ae70cd06f7c347db2a14599888a589525

parent: c01ae6a45d

Verified · cmc ci/build: success ci/lint: success ci/test: success

cmc <hello@cleberg.net> · 2026-09-11 18:48 UTC

Proxy random media with the token in the query, and bootstrap before listening

/api/random answered 401 with proxying on: sendMedia sliced the wixmp
URL and passed its query tail as the path, so the signing token never
reached wixmp as a parameter. It now parses the URL and hands the
subdomain, path and token to the same code the media route uses.

The first CSRF bootstrap runs before the listener opens, so requests in
the first seconds after a restart no longer go upstream without a
session and fail.

Layout: unified · split

app/api.go +15 −6

 import (
 	"encoding/json"
 	"math/rand"
+	"net/url"
 	"strings"
 	"github.com/krazywarez/devianter"
 		return
 	}
-	if CFG.Proxy {
+	if !CFG.Proxy {
-		mediaURL = mediaURL[21:]
-		dot := strings.Index(mediaURL, ".")
-		a.main.Writer.Header().Del("Content-Type")
-		a.main.DownloadAndSendMedia(mediaURL[:dot], mediaURL[dot+11:])
-	} else {
 		a.main.Writer.Header().Add("Location", mediaURL)
 		a.main.Writer.WriteHeader(302)
+		return
+	}
+	// Parsed, not sliced: the signing token has to reach wixmp as a query
+	// parameter. Passing the raw tail as the path put "?token=..." inside
+	// the path, which wixmp answers with 401.
+	u, err := url.Parse(mediaURL)
+	if err != nil {
+		a.Error("bad media url", 502)
+		return
 	}
+	subdomain := strings.TrimSuffix(strings.TrimPrefix(u.Host, "images-wixmp-"), ".wixmp.com")
+	a.main.Writer.Header().Del("Content-Type")
+	a.main.downloadAndSendMedia(subdomain, strings.TrimPrefix(u.Path, "/"), u.Query().Get("token"))
 }
 // fetchDailyDeviations is devianter.GetDailyDeviations behind a variable so

app/api_test.go +37

	@@ -1,7 +1,10 @@
1	package app	1	package app
2		2
3	import (	3	import (
		4	"net/http"
4	"net/http/httptest"	5	"net/http/httptest"
		6	"net/url"
		7	"strings"
5	"testing"	8	"testing"
6		9
7	"github.com/krazywarez/devianter"	10	"github.com/krazywarez/devianter"
	@@ -108,3 +111,37 @@ func TestRandomHonoursNSFW(t *testing.T) {
108	t.Errorf("status %d, Location %q; want 404 and no media", w.Code, w.Header().Get("Location"))	111	t.Errorf("status %d, Location %q; want 404 and no media", w.Code, w.Header().Get("Location"))
109	}	112	}
110	}	113	}
		114
		115	// TestSendMediaProxiesWithTheTokenInTheQuery is the regression test for
		116	// /api/random answering 401 with proxying on: the signing token was passed
		117	// inside the path, so wixmp never saw it as a parameter.
		118	func TestSendMediaProxiesWithTheTokenInTheQuery(t *testing.T) {
		119	proxy, cache := CFG.Proxy, CFG.Cache.Enabled
		120	CFG.Proxy, CFG.Cache.Enabled = true, false
		121	defer func() { CFG.Proxy, CFG.Cache.Enabled = proxy, cache }()
		122
		123	var fetched string
		124	orig := fetchMedia
		125	fetchMedia = func(u string) Downloaded {
		126	fetched = u
		127	return Downloaded{Status: 200, Body: []byte("png"), Headers: http.Header{"Content-Type": {"image/png"}}}
		128	}
		129	defer func() { fetchMedia = orig }()
		130
		131	d := fullviewDeviation()
		132	d.Media.Token = []string{"tok.en.sig"}
		133
		134	w := httptest.NewRecorder()
		135	API{main: &skunkyart{Writer: w, Args: url.Values{}}}.sendMedia(d)
		136
		137	u, err := url.Parse(fetched)
		138	if err != nil \|\| u.Host != "images-wixmp-abc.wixmp.com" {
		139	t.Fatalf("fetched %q, want a wixmp URL on the deviation's subdomain", fetched)
		140	}
		141	if strings.Contains(u.Path, "token") \|\| u.Query().Get("token") == "" {
		142	t.Errorf("token not passed as a query parameter: path %q query %q", u.Path, u.RawQuery)
		143	}
		144	if w.Code != 200 \|\| w.Body.String() != "png" {
		145	t.Errorf("response %d %q, want the proxied image", w.Code, w.Body.String())
		146	}
		147	}

app/cache.go +10 −3

 // client, serving it from the on-disk or in-memory cache when enabled. It
 // responds 403 when proxying is turned off for this instance.
 func (s skunkyart) DownloadAndSendMedia(subdomain, path string) {
-	mediaURL, ok := buildMediaURL(subdomain, path, s.Args.Get("token"))
+	s.downloadAndSendMedia(subdomain, path, s.Args.Get("token"))
+}
+// fetchMedia is Download behind a variable so tests can script the CDN.
+var fetchMedia = Download
+func (s skunkyart) downloadAndSendMedia(subdomain, path, token string) {
+	mediaURL, ok := buildMediaURL(subdomain, path, token)
 	if !ok {
 		s.ReturnHTTPError(400)
 		return
 			memPut(key, response)
 		}
 	case CFG.Proxy:
-		dwnld := Download(mediaURL)
+		dwnld := fetchMedia(mediaURL)
 		if dwnld.Status != 200 {
 			s.ReturnHTTPError(dwnld.Status)
 			return
 		}
 	}
-	dwnld := Download(mediaURL)
+	dwnld := fetchMedia(mediaURL)
 	if dwnld.Status != 200 || !strings.HasPrefix(dwnld.Headers.Get("Content-Type"), "image") {
 		s.ReturnHTTPError(dwnld.Status)
 		return nil, false

main.go +8 −3

 	// and let the request escape the throttle and the configured User-Agent.
 	go app.RefreshInstances()
+	// The first session bootstrap runs before the listener opens: requests
+	// that arrive before it finishes go to DeviantArt without a token and
+	// fail, which showed up as 502s for the first seconds after a restart.
+	if err := devianter.UpdateCSRF(); err != nil {
+		println(err.Error())
+	}
 	go func() {
 		for {
-			err := devianter.UpdateCSRF()
+			time.Sleep(12 * time.Hour)
-			if err != nil {
+			if err := devianter.UpdateCSRF(); err != nil {
 				println(err.Error())
 			}
-			time.Sleep(12 * time.Hour)
 		}
 	}()

Commit 48a4e98ae7

Commit `48a4e98ae7`