From e85181d0bb2d48083a0aa3b1bb92f4c99269682d Mon Sep 17 00:00:00 2001
From: Eriq Augustine <eriq.augustine@gmail.com>
Date: Sat, 16 Nov 2024 09:02:01 -0500
Subject: [PATCH] Added support for basic (not multipart) range requests for
 static files.

---
 sharkclipper/api/handlers.py | 64 +++++++++++++++++++++++++++++++++---
 sharkclipper/api/server.py   |  4 ++-
 2 files changed, 63 insertions(+), 5 deletions(-)

diff --git a/sharkclipper/api/handlers.py b/sharkclipper/api/handlers.py
index 0bc5d2f..8eae79f 100644
--- a/sharkclipper/api/handlers.py
+++ b/sharkclipper/api/handlers.py
@@ -41,7 +41,7 @@ def static(handler, path, **kwargs):
     # Build the static path skipping the '/static' part of the URL path.
     static_path = os.path.join(STATIC_DIR, *parts[2:])
 
-    return _serve_file(static_path, "static path not found: '%s'." % (path))
+    return _serve_file(static_path, "static path not found: '%s'." % (path), **kwargs)
 
 # Get a temp file that we create/work with.
 def temp(handler, path, temp_dir = None, **kwargs):
@@ -51,7 +51,7 @@ def temp(handler, path, temp_dir = None, **kwargs):
     # Build the temp path skipping the '/temp' part of the URL path.
     temp_path = os.path.join(temp_dir, *parts[2:])
 
-    return _serve_file(temp_path, "temp path not found: '%s'." % (path))
+    return _serve_file(temp_path, "temp path not found: '%s'." % (path), **kwargs)
 
 # Get the server version.
 def version(handler, path, **kwargs):
@@ -163,7 +163,7 @@ def _get_exif_timestamp(time):
     # Format.
     return time.strftime(EXIF_DATETIME_FORMAT)
 
-def _serve_file(path, not_found_message = None):
+def _serve_file(path, not_found_message = None, range_header = None, **kwargs):
     if (not os.path.isfile(path)):
         if (not_found_message is None):
             not_found_message = "path not found: '%s'." % (path)
@@ -178,4 +178,60 @@ def _serve_file(path, not_found_message = None):
     if (mime_info is not None):
         headers['Content-Type'] = mime_info[0]
 
-    return data, None, headers
+    code = http.HTTPStatus.OK
+
+    data_length = len(data)
+    range_parts = _parseRange(range_header, data_length)
+    if (range_parts is not None):
+        data = data[range_parts[0]:(range_parts[1] + 1)]
+        code = http.HTTPStatus.PARTIAL_CONTENT
+        headers['Content-Range'] = "bytes %d-%d/%d" % (range_parts[0], range_parts[1], data_length)
+
+    return data, code, headers
+
+# Parse the range header.
+# Return None if a single byte range could not be parsed (multi-ranges are not supported),
+# else return [startByteIndex, endByteIndex] (inclusive).
+# Note that the inclusivity means that these are not the same as a Python list slice
+# (you will need to add one to the end index).
+# If not present, startByteIndex will be defaulted to 0 and endByteIndex will be data_length.
+def _parseRange(raw_range_header, data_length):
+    try:
+        return _parseRangeHelper(raw_range_header, data_length)
+    except Exception as ex:
+        logging.warn("Cannot parse range header '%s': '%s'." % (raw_range_header, ex))
+        return None
+
+def _parseRangeHelper(raw_range_header, data_length):
+    if (raw_range_header is None):
+        return None
+
+    text = str(raw_range_header).strip().lower()
+
+    parts = [part.strip() for part in text.split('=')]
+    if (len(parts) != 2):
+        raise ValueError('Bad unit split.')
+
+    units, ranges = parts
+    if (units != 'bytes'):
+        raise ValueError('Units is not bytes.')
+
+    parts = [part.strip() for part in ranges.split(',')]
+    if (len(parts) != 1):
+        raise ValueError('Multipart ranges not supported.')
+
+    parts = [part.strip() for part in parts[0].split('-')]
+    if (len(parts) != 2):
+        raise ValueError('Range does not have exactly two components.')
+
+    start = parts[0]
+    if (start == ''):
+        start = 0
+    start = int(start)
+
+    end = parts[1]
+    if (end == ''):
+        end = (data_length - 1)
+    end = int(end)
+
+    return [start, end]
diff --git a/sharkclipper/api/server.py b/sharkclipper/api/server.py
index 0401aba..75668a7 100644
--- a/sharkclipper/api/server.py
+++ b/sharkclipper/api/server.py
@@ -107,10 +107,12 @@ def _read_post_file(self):
     def _do_request(self, **kwargs):
         logging.debug("Serving: " + self.path)
 
+        range_header = self.headers.get('Range', None)
+
         code = http.HTTPStatus.OK
         headers = {}
 
-        result = self._route(self.path, **kwargs)
+        result = self._route(self.path, range_header = range_header, **kwargs)
         if (result is None):
             # All handling was done internally, the response is complete.
             return