move download's get_header_param() to util, to use in soundcloud plugin

src/gpodder/download.py

@@ -78,30 +78,6 @@ class CustomDownloader:
         return None
 
 
-def get_header_param(headers, param, header_name):
-    """Extract a HTTP header parameter from a dict
-
-    Uses the "email" module to retrieve parameters
-    from HTTP headers. This can be used to get the
-    "filename" parameter of the "content-disposition"
-    header for downloads to pick a good filename.
-
-    Returns None if the filename cannot be retrieved.
-    """
-    value = None
-    try:
-        headers_string = ['%s:%s' % (k, v) for k, v in list(headers.items())]
-        msg = email.message_from_string('\n'.join(headers_string))
-        if header_name in msg:
-            raw_value = msg.get_param(param, header=header_name)
-            if raw_value is not None:
-                value = email.utils.collapse_rfc2231_value(raw_value)
-    except Exception as e:
-        logger.error('Cannot get %s from %s', param, header_name, exc_info=True)
-
-    return value
-
-
 class ContentRange(object):
     # Based on:
     # http://svn.pythonpaste.org/Paste/WebOb/trunk/webob/byterange.py
@@ -892,7 +868,7 @@ class DownloadTask(object):
                             real_url, os.path.basename(self.filename))
 
             # Look at the Content-disposition header; use if if available
-            disposition_filename = get_header_param(headers, 'filename', 'content-disposition')
+            disposition_filename = util.get_header_param(headers, 'filename', 'content-disposition')
 
             # Some servers do send the content-disposition header, but provide
             # an empty filename, resulting in an empty string here (bug 1440)

src/gpodder/plugins/soundcloud.py

@@ -54,28 +54,6 @@ def soundcloud_parsedate(s):
     return time.mktime(tuple([int(x) for x in m.groups()] + [0, 0, -1]))
 
 
-def get_param(s, param='filename', header='content-disposition'):
-    """Get a parameter from a string of headers
-
-    By default, this gets the "filename" parameter of
-    the content-disposition header. This works fine
-    for downloads from Soundcloud.
-    """
-    msg = email.message_from_string(s)
-    if header in msg:
-        value = msg.get_param(param, header=header)
-        decoded_list = email.header.decode_header(value)
-        value = []
-        for part, encoding in decoded_list:
-            if encoding:
-                value.append(part.decode(encoding))
-            else:
-                value.append(str(part))
-        return ''.join(value)
-
-    return None
-
-
 def get_metadata(url):
     """Get file download metadata
 
@@ -87,7 +65,8 @@ def get_metadata(url):
     filesize = track_response.headers['content-length'] or '0'
     filetype = track_response.headers['content-type'] or 'application/octet-stream'
     headers_s = '\n'.join('%s:%s' % (k, v) for k, v in list(track_response.headers.items()))
-    filename = get_param(headers_s) or os.path.basename(os.path.dirname(url))
+    filename = util.get_header_param(track_response.headers, 'filename', 'content-disposition') \
+        or os.path.basename(os.path.dirname(url))
     track_fp.close()
     return filesize, filetype, filename
 

src/gpodder/util.py

@@ -31,6 +31,7 @@ are not tied to any specific part of gPodder.
 """
 import collections
 import datetime
+import email
 import glob
 import gzip
 import http.client
@@ -2163,3 +2164,27 @@ def parse_mimetype(mimetype):
     except MIMETypeException as e:
         print(e)
         return (None, None, {})
+
+
+def get_header_param(headers, param, header_name):
+    """Extract a HTTP header parameter from a dict
+
+    Uses the "email" module to retrieve parameters
+    from HTTP headers. This can be used to get the
+    "filename" parameter of the "content-disposition"
+    header for downloads to pick a good filename.
+
+    Returns None if the filename cannot be retrieved.
+    """
+    value = None
+    try:
+        headers_string = ['%s:%s' % (k, v) for k, v in list(headers.items())]
+        msg = email.message_from_string('\n'.join(headers_string))
+        if header_name in msg:
+            raw_value = msg.get_param(param, header=header_name)
+            if raw_value is not None:
+                value = email.utils.collapse_rfc2231_value(raw_value)
+    except Exception as e:
+        logger.error('Cannot get %s from %s', param, header_name, exc_info=True)
+
+    return value