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fix(mime): register application/manifest+json for .webmanifest (+ webp/avif); v1.7.1

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Go's MIME table has no .webmanifest entry, so http.FileServer sniffed the PWA web
app manifest as text/plain. mime.AddExtensionType at package load makes TypeByExtension
authoritative. A correctness nit (the manifest spec parses by content and nosniff does
not reject manifests), but a PWA server should label its manifest correctly.
This commit is contained in:
Rene Nochebuena
2026-08-18 18:43:55 -06:00
parent b73b9ee022
commit d6665047d8
6 changed files with 62 additions and 13 deletions
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spa/handler_test.go
+18 -4
View File
@@ -6,6 +6,7 @@ import (
"net/http/httptest"
"os"
"path/filepath"
"strings"
"testing"
"code.nochebuena.dev/einherjar/contracts/logging"
@@ -20,10 +21,11 @@ func newTestHandler(t *testing.T) http.Handler {
t.Helper()
dir := t.TempDir()
for name, body := range map[string]string{
"index.html": "<!doctype html><title>app</title>",
"main.4f8a2b1c.js": "console.log(1)",
"favicon.ico": "icon",
"ngsw.json": "{}",
"index.html": "<!doctype html><title>app</title>",
"main.4f8a2b1c.js": "console.log(1)",
"favicon.ico": "icon",
"ngsw.json": "{}",
"manifest.webmanifest": `{"name":"app"}`,
} {
if err := os.WriteFile(filepath.Join(dir, name), []byte(body), 0o644); err != nil {
t.Fatal(err)
@@ -107,6 +109,18 @@ func TestFallback_RootServesIndex(t *testing.T) {
}
}
func TestManifestContentType(t *testing.T) {
// Without the mime registration this is sniffed as text/plain; with it the
// PWA manifest carries its registered type.
rec := get(newTestHandler(t), "/manifest.webmanifest", "*/*")
if rec.Code != http.StatusOK {
t.Fatalf("status = %d, want 200", rec.Code)
}
if ct := rec.Header().Get("Content-Type"); !strings.HasPrefix(ct, "application/manifest+json") {
t.Errorf("Content-Type = %q, want application/manifest+json", ct)
}
}
func TestIsHashed(t *testing.T) {
hashed := []string{"main.4f8a2b1c.js", "index-DkJf3x9a.js", "styles-4NDEUD5S.css", "app.a1b2c3d4.mjs"}
plain := []string{"favicon.ico", "index.html", "logo.png", "about.js", "main.js", "vendor.css"}
spa/mime.go
+24
View File
@@ -0,0 +1,24 @@
package spa
import "mime"
// Go's built-in MIME table — and a container image without /etc/mime.types — has no
// entry for these extensions, so http.FileServer falls back to content sniffing and
// mislabels them. The one that matters for a PWA server is the web app manifest,
// sniffed as text/plain instead of application/manifest+json. Registering the types
// once at package load makes mime.TypeByExtension authoritative, so the correct
// Content-Type is sent and no sniffing fallback runs.
//
// This is a correctness nit, not a fix for a live break: the manifest spec parses by
// content (valid JSON) rather than declared type, so browsers accept it either way.
// A PWA-focused server should still label it correctly. .webp/.avif get the same
// treatment for the same reason.
func init() {
for ext, typ := range map[string]string{
".webmanifest": "application/manifest+json",
".webp": "image/webp",
".avif": "image/avif",
} {
_ = mime.AddExtensionType(ext, typ)
}
}