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| author | Christian Cleberg <[email protected]> | 2026-07-15 03:17:09 -0500 |
|---|---|---|
| committer | Christian Cleberg <[email protected]> | 2026-07-15 03:17:09 -0500 |
| commit | 83d9cd0b7a3e0ec6beb5c889102211567a6db03f (patch) | |
| tree | 59926c27df295ba506d6f08a901274dd6d7c300c /app/util.go | |
| parent | 8d08f343c930f556c6ab016be9d00b23f1e516e3 (diff) | |
| download | skunky-art-83d9cd0b7a3e0ec6beb5c889102211567a6db03f.tar.gz skunky-art-83d9cd0b7a3e0ec6beb5c889102211567a6db03f.tar.bz2 skunky-art-83d9cd0b7a3e0ec6beb5c889102211567a6db03f.zip | |
fix: serve media again by unsetting download-proxy and scoping Host per request
Two independent faults made every image fail while pages still rendered.
config.example.json shipped download-proxy=http://127.0.0.1:8080. Only media
fetches go through that proxy — pages reach DeviantArt via devianter on the
default transport — so when nothing listens there, images 502 and the rest of
the page looks fine. In a scratch container 127.0.0.1 is the container itself,
so the default could never work under Docker. Unset it and document that it must
stay empty unless an operator really runs a proxy.
Host was a package global reassigned by every request, so a concurrent request
could overwrite it mid-render and emit URLs on another origin's host and port.
The instance's own default-src 'self' CSP then blocked those images. Thread the
request's host through skunkyart instead, and take it as an explicit argument in
URLBuilder, ParseMedia, ParseDescription, BuildUserPlate and
ConvertDeviantArtURLToSkunkyArt. Feeds keep their absolute URLs.
Also start RefreshInstances after ExecuteConfig rather than before it: the
goroutine read CFG while json.Unmarshal was writing it (a race the detector
flags), and its fetch escaped both the throttle and the configured User-Agent.
Verified: 300 concurrent requests with distinct Host headers now round-trip
their own host (was 1 leak per 300), go test -race is clean, and
cache+proxy both enabled serves 200 image/jpeg cold and from cache.
Diffstat (limited to 'app/util.go')
| -rwxr-xr-x | app/util.go | 41 |
1 files changed, 25 insertions, 16 deletions
diff --git a/app/util.go b/app/util.go index 8f0cba4..520dfbd 100755 --- a/app/util.go +++ b/app/util.go @@ -84,6 +84,11 @@ type skunkyart struct { Type rune Atom bool + // Host is the scheme and host this request arrived on, e.g. + // "https://art.example.com". It is per-request rather than global because + // concurrent requests can arrive on different hosts and ports. + Host string + BasePath, Endpoint string Query, QueryRaw string @@ -147,13 +152,15 @@ func (s skunkyart) ExecuteTemplate(file, dir string, data any) { wr(s.Writer, buf.String()) } -// URLBuilder joins strs into an absolute instance URL, prefixing the current -// Host and configured URI and inserting slashes between path segments but not -// before query separators. -func URLBuilder(strs ...string) string { +// URLBuilder joins strs into an absolute instance URL, prefixing host and the +// configured URI and inserting slashes between path segments but not before +// query separators. host is the request's own scheme and host: passing the +// wrong one emits links to another origin, which the instance's own +// Content-Security-Policy then blocks. +func URLBuilder(host string, strs ...string) string { var str strings.Builder l := len(strs) - str.WriteString(Host) + str.WriteString(host) str.WriteString(CFG.URI) for n, x := range strs { str.WriteString(x) @@ -170,7 +177,7 @@ func (s skunkyart) Error(dAerr devianter.Error) { var msg strings.Builder msg.WriteString(`<html><link rel="stylesheet" href="`) - msg.WriteString(URLBuilder("stylesheet")) + msg.WriteString(URLBuilder(s.Host, "stylesheet")) msg.WriteString(`" /><h3>DeviantArt error — '`) msg.WriteString(dAerr.Error) msg.WriteString("'</h3></html>") @@ -189,7 +196,7 @@ func (s skunkyart) ReturnHTTPError(status int) { var msg strings.Builder msg.WriteString(`<html><link rel="stylesheet" href="`) - msg.WriteString(URLBuilder("stylesheet")) + msg.WriteString(URLBuilder(s.Host, "stylesheet")) msg.WriteString(`" /><h1>`) msg.WriteString(strconv.Itoa(status)) msg.WriteString(" - ") @@ -264,7 +271,8 @@ func Download(urlString string) (d Downloaded) { // ParseMedia returns the URL to serve for media: a link back through this // instance's media proxy when proxying is on, or DeviantArt's own URL when it is // off. An optional thumb width selects a thumbnail instead of the full image. -func ParseMedia(media devianter.Media, thumb ...int) string { +// host is the request's scheme and host, as taken by URLBuilder. +func ParseMedia(host string, media devianter.Media, thumb ...int) string { mediaURL, filename := devianter.UrlFromMedia(media, thumb...) if len(mediaURL) != 0 && CFG.Proxy { mediaURL = mediaURL[21:] @@ -272,7 +280,7 @@ func ParseMedia(media devianter.Media, thumb ...int) string { if filename == "" { filename = "image.gif" } - return URLBuilder("media", "file", mediaURL[:dot], mediaURL[dot+11:], "&filename=", filename) + return URLBuilder(host, "media", "file", mediaURL[:dot], mediaURL[dot+11:], "&filename=", filename) } else if !CFG.Proxy { return mediaURL } @@ -281,27 +289,28 @@ func ParseMedia(media devianter.Media, thumb ...int) string { // ConvertDeviantArtURLToSkunkyArt rewrites a deviantart.com post link into the // equivalent link on this instance. It returns an empty string for URLs it does -// not handle, including sta.sh links. -func ConvertDeviantArtURLToSkunkyArt(url string) (output string) { +// not handle, including sta.sh links. host is the request's scheme and host, as +// taken by URLBuilder. +func ConvertDeviantArtURLToSkunkyArt(host, url string) (output string) { if len(url) > 32 && url[27:32] != "stash" { url = url[27:] firstshash := strings.Index(url, "/") lastshash := firstshash + strings.Index(url[firstshash+1:], "/") if lastshash != -1 { - output = URLBuilder("post", url[:firstshash], url[lastshash+2:]) + output = URLBuilder(host, "post", url[:firstshash], url[lastshash+2:]) } } return } // BuildUserPlate renders the small avatar-and-username block linking to a user's -// about page. -func BuildUserPlate(name string) string { +// about page. host is the request's scheme and host, as taken by URLBuilder. +func BuildUserPlate(host, name string) string { var htm strings.Builder htm.WriteString(`<div class="user-plate"><img src="`) - htm.WriteString(URLBuilder("media", "emojitar", name, "?type=a")) + htm.WriteString(URLBuilder(host, "media", "emojitar", name, "?type=a")) htm.WriteString(`"><a href="`) - htm.WriteString(URLBuilder("group_user", "?type=about&q=", name)) + htm.WriteString(URLBuilder(host, "group_user", "?type=about&q=", name)) htm.WriteString(`">`) htm.WriteString(name) htm.WriteString(`</a></div>`) |