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

middleware/content_type.go

@@ -0,0 +1,45 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+)
+
+// SetHeader is a convenience handler to set a response header key/value
+func SetHeader(key, value string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set(key, value)
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// AllowContentType enforces a whitelist of request Content-Types otherwise responds
+// with a 415 Unsupported Media Type status.
+func AllowContentType(contentTypes ...string) func(http.Handler) http.Handler {
+	allowedContentTypes := make(map[string]struct{}, len(contentTypes))
+	for _, ctype := range contentTypes {
+		allowedContentTypes[strings.TrimSpace(strings.ToLower(ctype))] = struct{}{}
+	}
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.ContentLength == 0 {
+				// Skip check for empty content body
+				next.ServeHTTP(w, r)
+				return
+			}
+
+			s, _, _ := strings.Cut(r.Header.Get("Content-Type"), ";")
+			s = strings.ToLower(strings.TrimSpace(s))
+
+			if _, ok := allowedContentTypes[s]; ok {
+				next.ServeHTTP(w, r)
+				return
+			}
+
+			w.WriteHeader(http.StatusUnsupportedMediaType)
+		})
+	}
+}