snapshot of https://github.com/go-chi/chi.git (master, 2026-09-15; blobs > 131072B omitted)

middleware/content_encoding.go

@@ -0,0 +1,34 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+)
+
+// AllowContentEncoding enforces a whitelist of request Content-Encoding otherwise responds
+// with a 415 Unsupported Media Type status.
+func AllowContentEncoding(contentEncoding ...string) func(next http.Handler) http.Handler {
+	allowedEncodings := make(map[string]struct{}, len(contentEncoding))
+	for _, encoding := range contentEncoding {
+		allowedEncodings[strings.TrimSpace(strings.ToLower(encoding))] = struct{}{}
+	}
+	return func(next http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+			requestEncodings := r.Header["Content-Encoding"]
+			// skip check for empty content body or no Content-Encoding
+			if r.ContentLength == 0 {
+				next.ServeHTTP(w, r)
+				return
+			}
+			// All encodings in the request must be allowed
+			for _, encoding := range requestEncodings {
+				if _, ok := allowedEncodings[strings.TrimSpace(strings.ToLower(encoding))]; !ok {
+					w.WriteHeader(http.StatusUnsupportedMediaType)
+					return
+				}
+			}
+			next.ServeHTTP(w, r)
+		}
+		return http.HandlerFunc(fn)
+	}
+}