Download HTML only as a link, not as a file

boards/models/attachment/downloaders.py

@@ -1,79 +1,95 b''
 import os
 import re
 
 from django.core.files.uploadedfile import SimpleUploadedFile, \
     TemporaryUploadedFile
 from pytube import YouTube
 import requests
 
 from boards.utils import validate_file_size
 
 YOUTUBE_VIDEO_FORMAT = 'webm'
 
 HTTP_RESULT_OK = 200
 
 HEADER_CONTENT_LENGTH = 'content-length'
 HEADER_CONTENT_TYPE = 'content-type'
 
 FILE_DOWNLOAD_CHUNK_BYTES = 200000
 
 YOUTUBE_URL = re.compile(r'https?://((www\.)?youtube\.com/watch\?v=|youtu.be/)[-\w]+')
 
+TYPE_URL_ONLY = (
+    'application/xhtml+xml',
+    'text/html',
+)
+
 
 class Downloader:
     @staticmethod
     def handles(url: str) -> bool:
         return False
 
     @staticmethod
     def download(url: str):
         # Verify content headers
         response_head = requests.head(url, verify=False)
         content_type = response_head.headers[HEADER_CONTENT_TYPE].split(';')[0]
         length_header = response_head.headers.get(HEADER_CONTENT_LENGTH)
         if length_header:
             length = int(length_header)
             validate_file_size(length)
         # Get the actual content into memory
         response = requests.get(url, verify=False, stream=True)
 
         # Download file, stop if the size exceeds limit
         size = 0
 
         # Set a dummy file name that will be replaced
         # anyway, just keep the valid extension
         filename = 'file.' + content_type.split('/')[1]
 
         file = TemporaryUploadedFile(filename, content_type, 0, None, None)
         for chunk in response.iter_content(FILE_DOWNLOAD_CHUNK_BYTES):
             size += len(chunk)
             validate_file_size(size)
             file.write(chunk)
 
         if response.status_code == HTTP_RESULT_OK:
             return file
 
 
 def download(url):
     for downloader in Downloader.__subclasses__():
         if downloader.handles(url):
             return downloader.download(url)
     # If nobody of the specific downloaders handles this, use generic
     # one
     return Downloader.download(url)
 
 
 class YouTubeDownloader(Downloader):
     @staticmethod
     def download(url: str):
         yt = YouTube()
         yt.from_url(url)
         videos = yt.filter(YOUTUBE_VIDEO_FORMAT)
         if len(videos) > 0:
             video = videos[0]
             return Downloader.download(video.url)
 
     @staticmethod
     def handles(url: str) -> bool:
         return YOUTUBE_URL.match(url)
 
+
+class NothingDownloader(Downloader):
+    @staticmethod
+    def handles(url: str) -> bool:
+        response_head = requests.head(url, verify=False)
+        content_type = response_head.headers[HEADER_CONTENT_TYPE].split(';')[0]
+        return content_type in TYPE_URL_ONLY
+
+    @staticmethod
+    def download(url: str):
+        return None