From 32a438e76cdec017e527fa4c22735714c3308b4b Mon Sep 17 00:00:00 2001
From: Hironsan <light.tree.1.13@gmail.com>
Date: Mon, 31 May 2021 13:59:12 +0900
Subject: [PATCH] Add middleware for range request

---
 backend/api/middleware.py | 35 +++++++++++++++++++++++++++++++++++
 backend/app/settings.py   |  3 +++
 2 files changed, 38 insertions(+)
 create mode 100644 backend/api/middleware.py

diff --git a/backend/api/middleware.py b/backend/api/middleware.py
new file mode 100644
index 00000000..83b7f5f8
--- /dev/null
+++ b/backend/api/middleware.py
@@ -0,0 +1,35 @@
+import os
+
+from django.utils.deprecation import MiddlewareMixin
+
+
+class RangesMiddleware(MiddlewareMixin):
+    """Quick solution. See:
+    https://stackoverflow.com/questions/14324250/byte-ranges-in-django/35928017#35928017
+    """
+
+    def process_response(self, request, response):
+        if response.status_code != 200 or not hasattr(response, 'file_to_stream'):
+            return response
+        http_range = request.META.get('HTTP_RANGE')
+        if not (http_range and http_range.startswith('bytes=') and http_range.count('-') == 1):
+            return response
+        if_range = request.META.get('HTTP_IF_RANGE')
+        if if_range and if_range != response.get('Last-Modified') and if_range != response.get('ETag'):
+            return response
+        f = response.file_to_stream
+        statobj = os.fstat(f.fileno())
+        start, end = http_range.split('=')[1].split('-')
+        if not start:  # requesting the last N bytes
+            start = max(0, statobj.st_size - int(end))
+            end = ''
+        start, end = int(start or 0), int(end or statobj.st_size - 1)
+        assert 0 <= start < statobj.st_size, (start, statobj.st_size)
+        end = min(end, statobj.st_size - 1)
+        f.seek(start)
+        old_read = f.read
+        f.read = lambda n: old_read(min(n, end + 1 - f.tell()))
+        response.status_code = 206
+        response['Content-Length'] = end + 1 - start
+        response['Content-Range'] = 'bytes %d-%d/%d' % (start, end, statobj.st_size)
+        return response
diff --git a/backend/app/settings.py b/backend/app/settings.py
index 67f6ef76..21851751 100644
--- a/backend/app/settings.py
+++ b/backend/app/settings.py
@@ -88,6 +88,9 @@ MIDDLEWARE = [
     'corsheaders.middleware.CorsMiddleware',
 ]
 
+if DEBUG:
+    MIDDLEWARE.append('api.middleware.RangesMiddleware')
+
 ROOT_URLCONF = 'app.urls'
 
 TEMPLATES = [