Index: Lib/http/formdata.py
===================================================================
--- Lib/http/formdata.py	(revision 0)
+++ Lib/http/formdata.py	(revision 0)
@@ -0,0 +1,87 @@
+# Copyright (C) 2010 Python Software Foundation
+# Author: Forest Bond
+
+'''
+This module implements MIMEMultipartFormData, a class for generating a MIME
+multipart/form-data message for submission to HTTP servers.  You would use this
+in an HTTP client to submit forms using Content-Type "multipart/form-data".
+This content type is described in RFC2388.
+
+Example usage with httplib.HTTPConnection:
+
+message = MIMEMultipartFormData()
+attachment = MIMEText('some test')
+message.attach_form_data(attachment, name='foo')
+attachment = MIMEApplication(bytes([0, 0, 0]), _subtype='octet-stream')
+message.attach_file(attachment, name='files', filename='bar.bin')
+
+headers = dict(message)
+body = message.get_body()
+
+conn = HTTPConnection('www.example.com')
+response = conn.send_request('POST', '/url', body, headers)
+'''
+
+from io import StringIO
+from email.mime.multipart import MIMEMultipart
+from email.generator import Generator
+
+
+class MIMEMultipartFormData(MIMEMultipart):
+    '''A simple RFC2388 multipart/form-data implementation.'''
+
+    def __init__(self, boundary=None, _subparts=None, **kwargs):
+        MIMEMultipart.__init__(self, _subtype='form-data',
+                boundary=boundary, _subparts=_subparts, **kwargs)
+
+    def attach(self, subpart):
+        if 'MIME-Version' in subpart:
+            if subpart['MIME-Version'] != self['MIME-Version']:
+                raise ValueError('subpart has incompatible MIME-Version')
+            # Note: This isn't strictly necessary, but there is no point in
+            # including a MIME-Version header in each subpart.
+            del subpart['MIME-Version']
+        MIMEMultipart.attach(self, subpart)
+
+    def attach_form_data(self, subpart, name):
+        '''
+        Attach a subpart, setting it's Content-Disposition header to
+        "form-data".
+        '''
+        name = name.replace('"', '\\"')
+        subpart['Content-Disposition'] = 'form-data; name="%s"' % name
+        self.attach(subpart)
+
+    def attach_file(self, subpart, name, filename):
+        '''
+        Attach a subpart, setting it's Content-Disposition header to "file".
+        '''
+        name = name.replace('"', '\\"')
+        filename = filename.replace('"', '\\"')
+        subpart['Content-Disposition'] = \
+          'file; name="%s"; filename="%s"' % (name, filename)
+        self.attach(subpart)
+
+    def get_body(self, trailing_newline=True):
+        '''Return the encoded message body.'''
+        f = StringIO()
+        generator = Generator(f, mangle_from_=False)
+        generator._dispatch(self)
+        # HTTP needs a trailing newline.  Since our return value is likely to
+        # be passed directly to an HTTP connection, we might as well add it
+        # here.
+        if trailing_newline:
+            f.write('\n')
+        return f.getvalue()
+
+    def as_string(self, trailing_newline=True):
+        '''Return the entire formatted message as a string.'''
+        f = StringIO()
+        generator = Generator(f, mangle_from_=False)
+        generator.flatten(self)
+        # HTTP needs a trailing newline.  Since our return value is likely to
+        # be passed directly to an HTTP connection, we might as well add it
+        # here.
+        if trailing_newline:
+            f.write('\n')
+        return f.getvalue()
Index: Lib/email/encoders.py
===================================================================
--- Lib/email/encoders.py	(revision 81683)
+++ Lib/email/encoders.py	(working copy)
@@ -29,7 +29,7 @@
     Also, add an appropriate Content-Transfer-Encoding header.
     """
     orig = msg.get_payload()
-    encdata = _bencode(orig)
+    encdata = str(_bencode(orig), 'ascii')
     msg.set_payload(encdata)
     msg['Content-Transfer-Encoding'] = 'base64'
 
Index: Lib/test/test_http_formdata.py
===================================================================
--- Lib/test/test_http_formdata.py	(revision 0)
+++ Lib/test/test_http_formdata.py	(revision 0)
@@ -0,0 +1,54 @@
+# Copyright (C) 2010 Python Software Foundation
+# Author: Forest Bond
+
+from http.formdata import MIMEMultipartFormData
+from email.mime.text import MIMEText
+from email.mime.application import MIMEApplication
+
+from unittest import TestCase
+from test import support
+
+
+class MIMEMultipartFormDataTests(TestCase):
+    def test(self):
+        msg = MIMEMultipartFormData(boundary='my-boundary')
+        attachment = MIMEText('some text')
+        msg.attach_form_data(attachment, name='foo')
+        attachment = MIMEApplication(bytes([0, 0, 0, 0, 0]),
+                _subtype='octet-stream')
+        msg.attach_file(attachment, name='files', filename='bar')
+
+        expected_headers = (
+          'Content-Type: multipart/form-data; boundary="my-boundary"\n'
+          'MIME-Version: 1.0\n'
+          '\n'
+        )
+        expected_body = (
+          '--my-boundary\n'
+          'Content-Type: text/plain; charset="us-ascii"\n'
+          'Content-Transfer-Encoding: 7bit\n'
+          'Content-Disposition: form-data; name="foo"\n'
+          '\n'
+          'some text\n'
+          '--my-boundary\n'
+          'Content-Type: application/octet-stream\n'
+          'Content-Transfer-Encoding: base64\n'
+          'Content-Disposition: file; name="files"; filename="bar"\n'
+          '\n'
+          'AAAAAAA=\n'
+          '--my-boundary--\n'
+        )
+
+        body = msg.get_body()
+        self.assertEqual(body, expected_body)
+
+        msg_str = msg.as_string()
+        self.assertEqual(msg_str, ''.join([expected_headers, expected_body]))
+
+
+def test_main(verbose=None):
+    support.run_unittest(MIMEMultipartFormDataTests)
+
+
+if __name__ == '__main__':
+    test_main()