[#3070] Fix httpdownloader error with missing content-disposition filename

The parsing of the content-disposition in httpdownloader was not able to
handle missing parameters e.g. "Content-Disposition: attachment" and would
result in an IndexError. Added a test for this use-case.

Fixed the issue using the cgi.parse_header to extract the parameters.

deluge/httpdownloader.py

@@ -9,6 +9,7 @@
 
 from __future__ import unicode_literals
 
+import cgi
 import logging
 import os.path
 import zlib
@@ -79,20 +80,23 @@ class HTTPDownloader(client.HTTPDownloader):
                 self.decoder = zlib.decompressobj(zlib.MAX_WBITS + 32)
 
             if 'content-disposition' in headers and not self.force_filename:
-                new_file_name = str(headers['content-disposition'][0]).split(';')[1].split('=')[1]
-                new_file_name = sanitise_filename(new_file_name)
-                new_file_name = os.path.join(os.path.split(self.value)[0], new_file_name)
+                content_disp = str(headers['content-disposition'][0])
+                content_disp_params = cgi.parse_header(content_disp)[1]
+                if 'filename' in content_disp_params:
+                    new_file_name = content_disp_params['filename']
+                    new_file_name = sanitise_filename(new_file_name)
+                    new_file_name = os.path.join(os.path.split(self.value)[0], new_file_name)
 
-                count = 1
-                fileroot = os.path.splitext(new_file_name)[0]
-                fileext = os.path.splitext(new_file_name)[1]
-                while os.path.isfile(new_file_name):
-                    # Increment filename if already exists
-                    new_file_name = '%s-%s%s' % (fileroot, count, fileext)
-                    count += 1
+                    count = 1
+                    fileroot = os.path.splitext(new_file_name)[0]
+                    fileext = os.path.splitext(new_file_name)[1]
+                    while os.path.isfile(new_file_name):
+                        # Increment filename if already exists
+                        new_file_name = '%s-%s%s' % (fileroot, count, fileext)
+                        count += 1
 
-                self.fileName = new_file_name
-                self.value = new_file_name
+                    self.fileName = new_file_name
+                    self.value = new_file_name
 
         elif self.code in (http.MOVED_PERMANENTLY, http.FOUND, http.SEE_OTHER, http.TEMPORARY_REDIRECT):
             location = headers['location'][0]

deluge/tests/test_httpdownloader.py

@@ -48,6 +48,14 @@ class RenameResource(Resource):
         return b'This file should be called ' + filename
 
 
+class AttachmentResource(Resource):
+
+    def render(self, request):
+        request.setHeader(b'Content-Type', b'text/plain')
+        request.setHeader(b'Content-Disposition', b'attachment')
+        return b'Attachement with no filename set'
+
+
 class CookieResource(Resource):
 
     def render(self, request):
@@ -99,6 +107,7 @@ class TopLevelResource(Resource):
         self.redirect_rsrc = RedirectResource()
         self.putChild('redirect', self.redirect_rsrc)
         self.putChild('rename', RenameResource())
+        self.putChild('attachment', AttachmentResource())
         self.putChild('partial', PartialDownloadResource())
 
     def getChild(self, path, request):  # NOQA: N802
@@ -195,6 +204,13 @@ class DownloadFileTestCase(unittest.TestCase):
         d.addCallback(self.assertContains, 'This file should be called /etc/passwd')
         return d
 
+    def test_download_with_attachment_no_filename(self):
+        url = self.get_url('attachment')
+        d = download_file(url, fname('original'))
+        d.addCallback(self.assertEqual, fname('original'))
+        d.addCallback(self.assertContains, 'Attachement with no filename set')
+        return d
+
     def test_download_with_rename_prevented(self):
         url = self.get_url('rename?filename=spam')
         d = download_file(url, fname('forced'), force_filename=True)