prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  UnicodeDecodeError in format_header_params
  This issue was discussed here: https://github.com/kennethreitz/requests/issues/2639 and it seemed like the consensus was that this should be fixed in urllib3. 
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `urllib3/fields.py`
  Content:
  ```
  1 from __future__ import absolute_import
  2 import email.utils
  3 import mimetypes
  4 
  5 from .packages import six
  6 
  7 
  8 def guess_content_type(filename, default='application/octet-stream'):
  9     """
  10     Guess the "Content-Type" of a file.
  11 
  12     :param filename:
  13         The filename to guess the "Content-Type" of using :mod:`mimetypes`.
  14     :param default:
  15         If no "Content-Type" can be guessed, default to `default`.
  16     """
  17     if filename:
  18         return mimetypes.guess_type(filename)[0] or default
  19     return default
  20 
  21 
  22 def format_header_param(name, value):
  23     """
  24     Helper function to format and quote a single header parameter.
  25 
  26     Particularly useful for header parameters which might contain
  27     non-ASCII values, like file names. This follows RFC 2231, as
  28     suggested by RFC 2388 Section 4.4.
  29 
  30     :param name:
  31         The name of the parameter, a string expected to be ASCII only.
  32     :param value:
  33         The value of the parameter, provided as a unicode string.
  34     """
  35     if not any(ch in value for ch in '"\\\r\n'):
  36         result = '%s="%s"' % (name, value)
  37         try:
  38             result.encode('ascii')
  39         except UnicodeEncodeError:
  40             pass
  41         else:
  42             return result
  43     if not six.PY3:  # Python 2:
  44         value = value.encode('utf-8')
  45     value = email.utils.encode_rfc2231(value, 'utf-8')
  46     value = '%s*=%s' % (name, value)
  47     return value
  48 
  49 
  50 class RequestField(object):
  51     """
  52     A data container for request body parameters.
  53 
  54     :param name:
  55         The name of this request field.
  56     :param data:
  57         The data/value body.
  58     :param filename:
  59         An optional filename of the request field.
  60     :param headers:
  61         An optional dict-like object of headers to initially use for the field.
  62     """
  63     def __init__(self, name, data, filename=None, headers=None):
  64         self._name = name
  65         self._filename = filename
  66         self.data = data
  67         self.headers = {}
  68         if headers:
  69             self.headers = dict(headers)
  70 
  71     @classmethod
  72     def from_tuples(cls, fieldname, value):
  73         """
  74         A :class:`~urllib3.fields.RequestField` factory from old-style tuple parameters.
  75 
  76         Supports constructing :class:`~urllib3.fields.RequestField` from
  77         parameter of key/value strings AND key/filetuple. A filetuple is a
  78         (filename, data, MIME type) tuple where the MIME type is optional.
  79         For example::
  80 
  81             'foo': 'bar',
  82             'fakefile': ('foofile.txt', 'contents of foofile'),
  83             'realfile': ('barfile.txt', open('realfile').read()),
  84             'typedfile': ('bazfile.bin', open('bazfile').read(), 'image/jpeg'),
  85             'nonamefile': 'contents of nonamefile field',
  86 
  87         Field names and filenames must be unicode.
  88         """
  89         if isinstance(value, tuple):
  90             if len(value) == 3:
  91                 filename, data, content_type = value
  92             else:
  93                 filename, data = value
  94                 content_type = guess_content_type(filename)
  95         else:
  96             filename = None
  97             content_type = None
  98             data = value
  99 
  100         request_param = cls(fieldname, data, filename=filename)
  101         request_param.make_multipart(content_type=content_type)
  102 
  103         return request_param
  104 
  105     def _render_part(self, name, value):
  106         """
  107         Overridable helper function to format a single header parameter.
  108 
  109         :param name:
  110             The name of the parameter, a string expected to be ASCII only.
  111         :param value:
  112             The value of the parameter, provided as a unicode string.
  113         """
  114         return format_header_param(name, value)
  115 
  116     def _render_parts(self, header_parts):
  117         """
  118         Helper function to format and quote a single header.
  119 
  120         Useful for single headers that are composed of multiple items. E.g.,
  121         'Content-Disposition' fields.
  122 
  123         :param header_parts:
  124             A sequence of (k, v) typles or a :class:`dict` of (k, v) to format
  125             as `k1="v1"; k2="v2"; ...`.
  126         """
  127         parts = []
  128         iterable = header_parts
  129         if isinstance(header_parts, dict):
  130             iterable = header_parts.items()
  131 
  132         for name, value in iterable:
  133             if value:
  134                 parts.append(self._render_part(name, value))
  135 
  136         return '; '.join(parts)
  137 
  138     def render_headers(self):
  139         """
  140         Renders the headers for this request field.
  141         """
  142         lines = []
  143 
  144         sort_keys = ['Content-Disposition', 'Content-Type', 'Content-Location']
  145         for sort_key in sort_keys:
  146             if self.headers.get(sort_key, False):
  147                 lines.append('%s: %s' % (sort_key, self.headers[sort_key]))
  148 
  149         for header_name, header_value in self.headers.items():
  150             if header_name not in sort_keys:
  151                 if header_value:
  152                     lines.append('%s: %s' % (header_name, header_value))
  153 
  154         lines.append('\r\n')
  155         return '\r\n'.join(lines)
  156 
  157     def make_multipart(self, content_disposition=None, content_type=None,
  158                        content_location=None):
  159         """
  160         Makes this request field into a multipart request field.
  161 
  162         This method overrides "Content-Disposition", "Content-Type" and
  163         "Content-Location" headers to the request parameter.
  164 
  165         :param content_type:
  166             The 'Content-Type' of the request body.
  167         :param content_location:
  168             The 'Content-Location' of the request body.
  169 
  170         """
  171         self.headers['Content-Disposition'] = content_disposition or 'form-data'
  172         self.headers['Content-Disposition'] += '; '.join([
  173             '', self._render_parts(
  174                 (('name', self._name), ('filename', self._filename))
  175             )
  176         ])
  177         self.headers['Content-Type'] = content_type
  178         self.headers['Content-Location'] = content_location
  179
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/urllib3/fields.py b/urllib3/fields.py
  --- a/urllib3/fields.py
  +++ b/urllib3/fields.py
  @@ -36,11 +36,11 @@
           result = '%s="%s"' % (name, value)
           try:
               result.encode('ascii')
  -        except UnicodeEncodeError:
  +        except (UnicodeEncodeError, UnicodeDecodeError):
               pass
           else:
               return result
  -    if not six.PY3:  # Python 2:
  +    if not six.PY3 and isinstance(value, six.text_type):  # Python 2:
           value = value.encode('utf-8')
       value = email.utils.encode_rfc2231(value, 'utf-8')
       value = '%s*=%s' % (name, value)
  
verification_info: {"golden_diff": "diff --git a/urllib3/fields.py b/urllib3/fields.py\n--- a/urllib3/fields.py\n+++ b/urllib3/fields.py\n@@ -36,11 +36,11 @@\n         result = '%s=\"%s\"' % (name, value)\n         try:\n             result.encode('ascii')\n-        except UnicodeEncodeError:\n+        except (UnicodeEncodeError, UnicodeDecodeError):\n             pass\n         else:\n             return result\n-    if not six.PY3:  # Python 2:\n+    if not six.PY3 and isinstance(value, six.text_type):  # Python 2:\n         value = value.encode('utf-8')\n     value = email.utils.encode_rfc2231(value, 'utf-8')\n     value = '%s*=%s' % (name, value)\n", "issue": "UnicodeDecodeError in format_header_params\nThis issue was discussed here: https://github.com/kennethreitz/requests/issues/2639 and it seemed like the consensus was that this should be fixed in urllib3. \n\n", "before_files": [{"content": "from __future__ import absolute_import\nimport email.utils\nimport mimetypes\n\nfrom .packages import six\n\n\ndef guess_content_type(filename, default='application/octet-stream'):\n    \"\"\"\n    Guess the \"Content-Type\" of a file.\n\n    :param filename:\n        The filename to guess the \"Content-Type\" of using :mod:`mimetypes`.\n    :param default:\n        If no \"Content-Type\" can be guessed, default to `default`.\n    \"\"\"\n    if filename:\n        return mimetypes.guess_type(filename)[0] or default\n    return default\n\n\ndef format_header_param(name, value):\n    \"\"\"\n    Helper function to format and quote a single header parameter.\n\n    Particularly useful for header parameters which might contain\n    non-ASCII values, like file names. This follows RFC 2231, as\n    suggested by RFC 2388 Section 4.4.\n\n    :param name:\n        The name of the parameter, a string expected to be ASCII only.\n    :param value:\n        The value of the parameter, provided as a unicode string.\n    \"\"\"\n    if not any(ch in value for ch in '\"\\\\\\r\\n'):\n        result = '%s=\"%s\"' % (name, value)\n        try:\n            result.encode('ascii')\n        except UnicodeEncodeError:\n            pass\n        else:\n            return result\n    if not six.PY3:  # Python 2:\n        value = value.encode('utf-8')\n    value = email.utils.encode_rfc2231(value, 'utf-8')\n    value = '%s*=%s' % (name, value)\n    return value\n\n\nclass RequestField(object):\n    \"\"\"\n    A data container for request body parameters.\n\n    :param name:\n        The name of this request field.\n    :param data:\n        The data/value body.\n    :param filename:\n        An optional filename of the request field.\n    :param headers:\n        An optional dict-like object of headers to initially use for the field.\n    \"\"\"\n    def __init__(self, name, data, filename=None, headers=None):\n        self._name = name\n        self._filename = filename\n        self.data = data\n        self.headers = {}\n        if headers:\n            self.headers = dict(headers)\n\n    @classmethod\n    def from_tuples(cls, fieldname, value):\n        \"\"\"\n        A :class:`~urllib3.fields.RequestField` factory from old-style tuple parameters.\n\n        Supports constructing :class:`~urllib3.fields.RequestField` from\n        parameter of key/value strings AND key/filetuple. A filetuple is a\n        (filename, data, MIME type) tuple where the MIME type is optional.\n        For example::\n\n            'foo': 'bar',\n            'fakefile': ('foofile.txt', 'contents of foofile'),\n            'realfile': ('barfile.txt', open('realfile').read()),\n            'typedfile': ('bazfile.bin', open('bazfile').read(), 'image/jpeg'),\n            'nonamefile': 'contents of nonamefile field',\n\n        Field names and filenames must be unicode.\n        \"\"\"\n        if isinstance(value, tuple):\n            if len(value) == 3:\n                filename, data, content_type = value\n            else:\n                filename, data = value\n                content_type = guess_content_type(filename)\n        else:\n            filename = None\n            content_type = None\n            data = value\n\n        request_param = cls(fieldname, data, filename=filename)\n        request_param.make_multipart(content_type=content_type)\n\n        return request_param\n\n    def _render_part(self, name, value):\n        \"\"\"\n        Overridable helper function to format a single header parameter.\n\n        :param name:\n            The name of the parameter, a string expected to be ASCII only.\n        :param value:\n            The value of the parameter, provided as a unicode string.\n        \"\"\"\n        return format_header_param(name, value)\n\n    def _render_parts(self, header_parts):\n        \"\"\"\n        Helper function to format and quote a single header.\n\n        Useful for single headers that are composed of multiple items. E.g.,\n        'Content-Disposition' fields.\n\n        :param header_parts:\n            A sequence of (k, v) typles or a :class:`dict` of (k, v) to format\n            as `k1=\"v1\"; k2=\"v2\"; ...`.\n        \"\"\"\n        parts = []\n        iterable = header_parts\n        if isinstance(header_parts, dict):\n            iterable = header_parts.items()\n\n        for name, value in iterable:\n            if value:\n                parts.append(self._render_part(name, value))\n\n        return '; '.join(parts)\n\n    def render_headers(self):\n        \"\"\"\n        Renders the headers for this request field.\n        \"\"\"\n        lines = []\n\n        sort_keys = ['Content-Disposition', 'Content-Type', 'Content-Location']\n        for sort_key in sort_keys:\n            if self.headers.get(sort_key, False):\n                lines.append('%s: %s' % (sort_key, self.headers[sort_key]))\n\n        for header_name, header_value in self.headers.items():\n            if header_name not in sort_keys:\n                if header_value:\n                    lines.append('%s: %s' % (header_name, header_value))\n\n        lines.append('\\r\\n')\n        return '\\r\\n'.join(lines)\n\n    def make_multipart(self, content_disposition=None, content_type=None,\n                       content_location=None):\n        \"\"\"\n        Makes this request field into a multipart request field.\n\n        This method overrides \"Content-Disposition\", \"Content-Type\" and\n        \"Content-Location\" headers to the request parameter.\n\n        :param content_type:\n            The 'Content-Type' of the request body.\n        :param content_location:\n            The 'Content-Location' of the request body.\n\n        \"\"\"\n        self.headers['Content-Disposition'] = content_disposition or 'form-data'\n        self.headers['Content-Disposition'] += '; '.join([\n            '', self._render_parts(\n                (('name', self._name), ('filename', self._filename))\n            )\n        ])\n        self.headers['Content-Type'] = content_type\n        self.headers['Content-Location'] = content_location\n", "path": "urllib3/fields.py"}], "after_files": [{"content": "from __future__ import absolute_import\nimport email.utils\nimport mimetypes\n\nfrom .packages import six\n\n\ndef guess_content_type(filename, default='application/octet-stream'):\n    \"\"\"\n    Guess the \"Content-Type\" of a file.\n\n    :param filename:\n        The filename to guess the \"Content-Type\" of using :mod:`mimetypes`.\n    :param default:\n        If no \"Content-Type\" can be guessed, default to `default`.\n    \"\"\"\n    if filename:\n        return mimetypes.guess_type(filename)[0] or default\n    return default\n\n\ndef format_header_param(name, value):\n    \"\"\"\n    Helper function to format and quote a single header parameter.\n\n    Particularly useful for header parameters which might contain\n    non-ASCII values, like file names. This follows RFC 2231, as\n    suggested by RFC 2388 Section 4.4.\n\n    :param name:\n        The name of the parameter, a string expected to be ASCII only.\n    :param value:\n        The value of the parameter, provided as a unicode string.\n    \"\"\"\n    if not any(ch in value for ch in '\"\\\\\\r\\n'):\n        result = '%s=\"%s\"' % (name, value)\n        try:\n            result.encode('ascii')\n        except (UnicodeEncodeError, UnicodeDecodeError):\n            pass\n        else:\n            return result\n    if not six.PY3 and isinstance(value, six.text_type):  # Python 2:\n        value = value.encode('utf-8')\n    value = email.utils.encode_rfc2231(value, 'utf-8')\n    value = '%s*=%s' % (name, value)\n    return value\n\n\nclass RequestField(object):\n    \"\"\"\n    A data container for request body parameters.\n\n    :param name:\n        The name of this request field.\n    :param data:\n        The data/value body.\n    :param filename:\n        An optional filename of the request field.\n    :param headers:\n        An optional dict-like object of headers to initially use for the field.\n    \"\"\"\n    def __init__(self, name, data, filename=None, headers=None):\n        self._name = name\n        self._filename = filename\n        self.data = data\n        self.headers = {}\n        if headers:\n            self.headers = dict(headers)\n\n    @classmethod\n    def from_tuples(cls, fieldname, value):\n        \"\"\"\n        A :class:`~urllib3.fields.RequestField` factory from old-style tuple parameters.\n\n        Supports constructing :class:`~urllib3.fields.RequestField` from\n        parameter of key/value strings AND key/filetuple. A filetuple is a\n        (filename, data, MIME type) tuple where the MIME type is optional.\n        For example::\n\n            'foo': 'bar',\n            'fakefile': ('foofile.txt', 'contents of foofile'),\n            'realfile': ('barfile.txt', open('realfile').read()),\n            'typedfile': ('bazfile.bin', open('bazfile').read(), 'image/jpeg'),\n            'nonamefile': 'contents of nonamefile field',\n\n        Field names and filenames must be unicode.\n        \"\"\"\n        if isinstance(value, tuple):\n            if len(value) == 3:\n                filename, data, content_type = value\n            else:\n                filename, data = value\n                content_type = guess_content_type(filename)\n        else:\n            filename = None\n            content_type = None\n            data = value\n\n        request_param = cls(fieldname, data, filename=filename)\n        request_param.make_multipart(content_type=content_type)\n\n        return request_param\n\n    def _render_part(self, name, value):\n        \"\"\"\n        Overridable helper function to format a single header parameter.\n\n        :param name:\n            The name of the parameter, a string expected to be ASCII only.\n        :param value:\n            The value of the parameter, provided as a unicode string.\n        \"\"\"\n        return format_header_param(name, value)\n\n    def _render_parts(self, header_parts):\n        \"\"\"\n        Helper function to format and quote a single header.\n\n        Useful for single headers that are composed of multiple items. E.g.,\n        'Content-Disposition' fields.\n\n        :param header_parts:\n            A sequence of (k, v) typles or a :class:`dict` of (k, v) to format\n            as `k1=\"v1\"; k2=\"v2\"; ...`.\n        \"\"\"\n        parts = []\n        iterable = header_parts\n        if isinstance(header_parts, dict):\n            iterable = header_parts.items()\n\n        for name, value in iterable:\n            if value:\n                parts.append(self._render_part(name, value))\n\n        return '; '.join(parts)\n\n    def render_headers(self):\n        \"\"\"\n        Renders the headers for this request field.\n        \"\"\"\n        lines = []\n\n        sort_keys = ['Content-Disposition', 'Content-Type', 'Content-Location']\n        for sort_key in sort_keys:\n            if self.headers.get(sort_key, False):\n                lines.append('%s: %s' % (sort_key, self.headers[sort_key]))\n\n        for header_name, header_value in self.headers.items():\n            if header_name not in sort_keys:\n                if header_value:\n                    lines.append('%s: %s' % (header_name, header_value))\n\n        lines.append('\\r\\n')\n        return '\\r\\n'.join(lines)\n\n    def make_multipart(self, content_disposition=None, content_type=None,\n                       content_location=None):\n        \"\"\"\n        Makes this request field into a multipart request field.\n\n        This method overrides \"Content-Disposition\", \"Content-Type\" and\n        \"Content-Location\" headers to the request parameter.\n\n        :param content_type:\n            The 'Content-Type' of the request body.\n        :param content_location:\n            The 'Content-Location' of the request body.\n\n        \"\"\"\n        self.headers['Content-Disposition'] = content_disposition or 'form-data'\n        self.headers['Content-Disposition'] += '; '.join([\n            '', self._render_parts(\n                (('name', self._name), ('filename', self._filename))\n            )\n        ])\n        self.headers['Content-Type'] = content_type\n        self.headers['Content-Location'] = content_location\n", "path": "urllib3/fields.py"}]}