first commit

internal/http/middleware/bodylimit.go

@@ -0,0 +1,19 @@
+package middleware
+
+import "net/http"
+
+// BodyLimit caps request body size. Returns 413 if exceeded.
+func BodyLimit(maxBytes int64) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.ContentLength > maxBytes {
+				w.Header().Set("Content-Type", "application/json")
+				w.WriteHeader(http.StatusRequestEntityTooLarge)
+				_, _ = w.Write([]byte(`{"error":"PayloadTooLarge","detail":"request body exceeds limit"}`))
+				return
+			}
+			r.Body = http.MaxBytesReader(w, r.Body, maxBytes)
+			next.ServeHTTP(w, r)
+		})
+	}
+}