add MultiDict

This commit introduces MultiDict, a multi-dictionary similar to
ODict, but with improved semantics (as in the Headers class).
MultiDict fixes a few issues that were present in the Request/Response
API. In particular, `request.cookies["foo"] = "bar"` has previously been a
no-op, as the cookies property returned a mutable _copy_ of the cookies.

23 files changed, 370 insertions, 265 deletions

diff --git a/examples/modify_form.py b/examples/modify_form.py
index 86188781..c4edb2cd 100644
--- a/examples/modify_form.py
+++ b/examples/modify_form.py
@@ -1,5 +1,8 @@
 def request(context, flow):
-    form = flow.request.urlencoded_form
-    if form is not None:
-        form["mitmproxy"] = ["rocks"]
-        flow.request.urlencoded_form = form
+    if flow.request.urlencoded_form is not None:
+        flow.request.urlencoded_form["mitmproxy"] = "rocks"
+    else:
+        # This sets the proper content type and overrides the body.
+        flow.request.urlencoded_form = [
+            ("foo", "bar")
+        ]
diff --git a/examples/modify_querystring.py b/examples/modify_querystring.py
index d682df69..b89e5c8d 100644
--- a/examples/modify_querystring.py
+++ b/examples/modify_querystring.py
@@ -1,5 +1,2 @@
 def request(context, flow):
-    q = flow.request.query
-    if q:
-        q["mitmproxy"] = ["rocks"]
-        flow.request.query = q
+    flow.request.query["mitmproxy"] = "rocks"
diff --git a/mitmproxy/flow.py b/mitmproxy/flow.py
index 7fd97af3..4663144d 100644
--- a/mitmproxy/flow.py
+++ b/mitmproxy/flow.py
@@ -156,9 +156,9 @@ class SetHeaders:
         for _, header, value, cpatt in self.lst:
             if cpatt(f):
                 if f.response:
-                    f.response.headers.fields.append((header, value))
+                    f.response.headers.add(header, value)
                 else:
-                    f.request.headers.fields.append((header, value))
+                    f.request.headers.add(header, value)
 
 
 class StreamLargeBodies(object):
@@ -263,7 +263,7 @@ class ServerPlaybackState:
             form_contents = r.urlencoded_form or r.multipart_form
             if self.ignore_payload_params and form_contents:
                 key.extend(
-                    p for p in form_contents
+                    p for p in form_contents.items(multi=True)
                     if p[0] not in self.ignore_payload_params
                 )
             else:
@@ -354,7 +354,7 @@ class StickyCookieState:
                 ]
                 if all(match):
                     c = self.jar[i]
-                    l.extend([cookies.format_cookie_header(c[name]) for name in c.keys()])
+                    l.extend([cookies.format_cookie_header(c[name].lst) for name in c.keys()])
         if l:
             f.request.stickycookie = True
             f.request.headers["cookie"] = "; ".join(l)
diff --git a/mitmproxy/flow_export.py b/mitmproxy/flow_export.py
index d8e65704..ae282fce 100644
--- a/mitmproxy/flow_export.py
+++ b/mitmproxy/flow_export.py
@@ -51,7 +51,7 @@ def python_code(flow):
 
     params = ""
     if flow.request.query:
-        lines = ["    '%s': '%s',\n" % (k, v) for k, v in flow.request.query]
+        lines = ["    %s: %s,\n" % (repr(k), repr(v)) for k, v in flow.request.query.to_dict().items()]
         params = "\nparams = {\n%s}\n" % "".join(lines)
         args += "\n    params=params,"
 
@@ -140,7 +140,7 @@ def locust_code(flow):
 
     params = ""
     if flow.request.query:
-        lines = ["            '%s': '%s',\n" % (k, v) for k, v in flow.request.query]
+        lines = ["            %s: %s,\n" % (repr(k), repr(v)) for k, v in flow.request.query.to_dict().items()]
         params = "\n        params = {\n%s        }\n" % "".join(lines)
         args += "\n            params=params,"
 
diff --git a/netlib/encoding.py b/netlib/encoding.py
index 14479e00..98502451 100644
--- a/netlib/encoding.py
+++ b/netlib/encoding.py
@@ -5,7 +5,6 @@ from __future__ import absolute_import
 from io import BytesIO
 import gzip
 import zlib
-from .utils import always_byte_args
 
 
 ENCODINGS = {"identity", "gzip", "deflate"}
diff --git a/netlib/http/cookies.py b/netlib/http/cookies.py
index 4451f1da..fd531146 100644
--- a/netlib/http/cookies.py
+++ b/netlib/http/cookies.py
@@ -1,6 +1,4 @@
-from six.moves import http_cookies as Cookie
 import re
-import string
 from email.utils import parsedate_tz, formatdate, mktime_tz
 
 from .. import odict
@@ -179,20 +177,27 @@ def format_set_cookie_header(name, value, attrs):
     return _format_set_cookie_pairs(pairs)
 
 
+def parse_cookie_headers(cookie_headers):
+    cookie_list = []
+    for header in cookie_headers:
+        cookie_list.extend(parse_cookie_header(header))
+    return cookie_list
+
+
 def parse_cookie_header(line):
     """
         Parse a Cookie header value.
-        Returns a (possibly empty) ODict object.
+        Returns a list of (lhs, rhs) tuples.
     """
     pairs, off_ = _read_pairs(line)
-    return odict.ODict(pairs)
+    return pairs
 
 
-def format_cookie_header(od):
+def format_cookie_header(lst):
     """
         Formats a Cookie header value.
     """
-    return _format_pairs(od.lst)
+    return _format_pairs(lst)
 
 
 def refresh_set_cookie_header(c, delta):
diff --git a/netlib/http/headers.py b/netlib/http/headers.py
index 72739f90..7e39c371 100644
--- a/netlib/http/headers.py
+++ b/netlib/http/headers.py
@@ -1,9 +1,3 @@
-"""
-
-Unicode Handling
-----------------
-See also: http://lucumr.pocoo.org/2013/7/2/the-updated-guide-to-unicode/
-"""
 from __future__ import absolute_import, print_function, division
 
 import re
@@ -13,23 +7,22 @@ try:
 except ImportError:  # pragma: no cover
     from collections import MutableMapping  # Workaround for Python < 3.3
 
-
 import six
+from ..multidict import MultiDict
+from ..utils import always_bytes
 
-from netlib.utils import always_byte_args, always_bytes, Serializable
+# See also: http://lucumr.pocoo.org/2013/7/2/the-updated-guide-to-unicode/
 
 if six.PY2:  # pragma: no cover
     _native = lambda x: x
     _always_bytes = lambda x: x
-    _always_byte_args = lambda x: x
 else:
     # While headers _should_ be ASCII, it's not uncommon for certain headers to be utf-8 encoded.
     _native = lambda x: x.decode("utf-8", "surrogateescape")
     _always_bytes = lambda x: always_bytes(x, "utf-8", "surrogateescape")
-    _always_byte_args = always_byte_args("utf-8", "surrogateescape")
 
 
-class Headers(MutableMapping, Serializable):
+class Headers(MultiDict):
     """
     Header class which allows both convenient access to individual headers as well as
     direct access to the underlying raw data. Provides a full dictionary interface.
@@ -49,7 +42,7 @@ class Headers(MutableMapping, Serializable):
         >>> h["host"]
         "example.com"
 
-        # Headers can also be creatd from a list of raw (header_name, header_value) byte tuples
+        # Headers can also be created from a list of raw (header_name, header_value) byte tuples
         >>> h = Headers([
             [b"Host",b"example.com"],
             [b"Accept",b"text/html"],
@@ -77,7 +70,6 @@ class Headers(MutableMapping, Serializable):
         For use with the "Set-Cookie" header, see :py:meth:`get_all`.
     """
 
-    @_always_byte_args
     def __init__(self, fields=None, **headers):
         """
         Args:
@@ -89,19 +81,25 @@ class Headers(MutableMapping, Serializable):
                 If ``**headers`` contains multiple keys that have equal ``.lower()`` s,
                 the behavior is undefined.
         """
-        self.fields = fields or []
-
-        for name, value in self.fields:
-            if not isinstance(name, bytes) or not isinstance(value, bytes):
-                raise ValueError("Headers passed as fields must be bytes.")
+        super(Headers, self).__init__(fields)
 
         # content_type -> content-type
         headers = {
-            _always_bytes(name).replace(b"_", b"-"): value
+            _always_bytes(name).replace(b"_", b"-"): _always_bytes(value)
             for name, value in six.iteritems(headers)
             }
         self.update(headers)
 
+    @staticmethod
+    def _reduce_values(values):
+        # Headers can be folded
+        return ", ".join(values)
+
+    @staticmethod
+    def _kconv(key):
+        # Headers are case-insensitive
+        return key.lower()
+
     def __bytes__(self):
         if self.fields:
             return b"\r\n".join(b": ".join(field) for field in self.fields) + b"\r\n"
@@ -111,98 +109,40 @@ class Headers(MutableMapping, Serializable):
     if six.PY2:  # pragma: no cover
         __str__ = __bytes__
 
-    @_always_byte_args
-    def __getitem__(self, name):
-        values = self.get_all(name)
-        if not values:
-            raise KeyError(name)
-        return ", ".join(values)
-
-    @_always_byte_args
-    def __setitem__(self, name, value):
-        idx = self._index(name)
-
-        # To please the human eye, we insert at the same position the first existing header occured.
-        if idx is not None:
-            del self[name]
-            self.fields.insert(idx, [name, value])
-        else:
-            self.fields.append([name, value])
-
-    @_always_byte_args
-    def __delitem__(self, name):
-        if name not in self:
-            raise KeyError(name)
-        name = name.lower()
-        self.fields = [
-            field for field in self.fields
-            if name != field[0].lower()
-        ]
+    def __delitem__(self, key):
+        key = _always_bytes(key)
+        super(Headers, self).__delitem__(key)
 
     def __iter__(self):
-        seen = set()
-        for name, _ in self.fields:
-            name_lower = name.lower()
-            if name_lower not in seen:
-                seen.add(name_lower)
-                yield _native(name)
-
-    def __len__(self):
-        return len(set(name.lower() for name, _ in self.fields))
-
-    # __hash__ = object.__hash__
-
-    def _index(self, name):
-        name = name.lower()
-        for i, field in enumerate(self.fields):
-            if field[0].lower() == name:
-                return i
-        return None
-
-    def __eq__(self, other):
-        if isinstance(other, Headers):
-            return self.fields == other.fields
-        return False
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
-
-    @_always_byte_args
+        for x in super(Headers, self).__iter__():
+            yield _native(x)
+
     def get_all(self, name):
         """
         Like :py:meth:`get`, but does not fold multiple headers into a single one.
         This is useful for Set-Cookie headers, which do not support folding.
-
         See also: https://tools.ietf.org/html/rfc7230#section-3.2.2
         """
-        name_lower = name.lower()
-        values = [_native(value) for n, value in self.fields if n.lower() == name_lower]
-        return values
+        name = _always_bytes(name)
+        return [
+            _native(x) for x in
+            super(Headers, self).get_all(name)
+        ]
 
-    @_always_byte_args
     def set_all(self, name, values):
         """
         Explicitly set multiple headers for the given key.
         See: :py:meth:`get_all`
         """
-        values = map(_always_bytes, values)  # _always_byte_args does not fix lists
-        if name in self:
-            del self[name]
-        self.fields.extend(
-            [name, value] for value in values
-        )
-
-    def get_state(self):
-        return tuple(tuple(field) for field in self.fields)
-
-    def set_state(self, state):
-        self.fields = [list(field) for field in state]
+        name = _always_bytes(name)
+        values = [_always_bytes(x) for x in values]
+        return super(Headers, self).set_all(name, values)
 
-    @classmethod
-    def from_state(cls, state):
-        return cls([list(field) for field in state])
+    def insert(self, index, key, value):
+        key = _always_bytes(key)
+        value = _always_bytes(value)
+        super(Headers, self).insert(index, key, value)
 
-    @_always_byte_args
     def replace(self, pattern, repl, flags=0):
         """
         Replaces a regular expression pattern with repl in each "name: value"
@@ -211,6 +151,8 @@ class Headers(MutableMapping, Serializable):
         Returns:
             The number of replacements made.
         """
+        pattern = _always_bytes(pattern)
+        repl = _always_bytes(repl)
         pattern = re.compile(pattern, flags)
         replacements = 0
 
diff --git a/netlib/http/http1/read.py b/netlib/http/http1/read.py
index 6e3a1b93..d30976bd 100644
--- a/netlib/http/http1/read.py
+++ b/netlib/http/http1/read.py
@@ -316,14 +316,14 @@ def _read_headers(rfile):
             if not ret:
                 raise HttpSyntaxException("Invalid headers")
             # continued header
-            ret[-1][1] = ret[-1][1] + b'\r\n ' + line.strip()
+            ret[-1] = (ret[-1][0], ret[-1][1] + b'\r\n ' + line.strip())
         else:
             try:
                 name, value = line.split(b":", 1)
                 value = value.strip()
                 if not name:
                     raise ValueError()
-                ret.append([name, value])
+                ret.append((name, value))
             except ValueError:
                 raise HttpSyntaxException("Invalid headers")
     return Headers(ret)
diff --git a/netlib/http/http2/connections.py b/netlib/http/http2/connections.py
index f900b67c..6643b6b9 100644
--- a/netlib/http/http2/connections.py
+++ b/netlib/http/http2/connections.py
@@ -201,13 +201,13 @@ class HTTP2Protocol(object):
         headers = request.headers.copy()
 
         if ':authority' not in headers:
-            headers.fields.insert(0, (b':authority', authority.encode('ascii')))
+            headers.insert(0, b':authority', authority.encode('ascii'))
         if ':scheme' not in headers:
-            headers.fields.insert(0, (b':scheme', request.scheme.encode('ascii')))
+            headers.insert(0, b':scheme', request.scheme.encode('ascii'))
         if ':path' not in headers:
-            headers.fields.insert(0, (b':path', request.path.encode('ascii')))
+            headers.insert(0, b':path', request.path.encode('ascii'))
         if ':method' not in headers:
-            headers.fields.insert(0, (b':method', request.method.encode('ascii')))
+            headers.insert(0, b':method', request.method.encode('ascii'))
 
         if hasattr(request, 'stream_id'):
             stream_id = request.stream_id
@@ -224,7 +224,7 @@ class HTTP2Protocol(object):
         headers = response.headers.copy()
 
         if ':status' not in headers:
-            headers.fields.insert(0, (b':status', str(response.status_code).encode('ascii')))
+            headers.insert(0, b':status', str(response.status_code).encode('ascii'))
 
         if hasattr(response, 'stream_id'):
             stream_id = response.stream_id
@@ -420,7 +420,7 @@ class HTTP2Protocol(object):
                 self._handle_unexpected_frame(frm)
 
         headers = Headers(
-            [[k.encode('ascii'), v.encode('ascii')] for k, v in self.decoder.decode(header_blocks)]
+            (k.encode('ascii'), v.encode('ascii')) for k, v in self.decoder.decode(header_blocks)
         )
 
         return stream_id, headers, body
diff --git a/netlib/http/message.py b/netlib/http/message.py
index da9681a0..262ef3e1 100644
--- a/netlib/http/message.py
+++ b/netlib/http/message.py
@@ -4,6 +4,7 @@ import warnings
 
 import six
 
+from ..multidict import MultiDict
 from .headers import Headers
 from .. import encoding, utils
 
@@ -235,3 +236,37 @@ class decoded(object):
     def __exit__(self, type, value, tb):
         if self.ce:
             self.message.encode(self.ce)
+
+
+class MessageMultiDict(MultiDict):
+    """
+    A MultiDict that provides a proxy view to the underlying message.
+    """
+
+    def __init__(self, attr, message):
+        if False:
+            # We do not want to call the parent constructor here as that
+            # would cause an unnecessary parse/unparse pass.
+            # This is here to silence linters. Message
+            super(MessageMultiDict, self).__init__(None)
+        self._attr = attr
+        self._message = message  # type: Message
+
+    @staticmethod
+    def _kconv(key):
+        # All request-attributes are case-sensitive.
+        return key
+
+    @staticmethod
+    def _reduce_values(values):
+        # We just return the first element if
+        # multiple elements exist with the same key.
+        return values[0]
+
+    @property
+    def fields(self):
+        return getattr(self._message, "_" + self._attr)
+
+    @fields.setter
+    def fields(self, value):
+        setattr(self._message, self._attr, value)
diff --git a/netlib/http/request.py b/netlib/http/request.py
index a42150ff..26ec12cf 100644
--- a/netlib/http/request.py
+++ b/netlib/http/request.py
@@ -11,7 +11,7 @@ from netlib.http import cookies
 from netlib.odict import ODict
 from .. import encoding
 from .headers import Headers
-from .message import Message, _native, _always_bytes, MessageData
+from .message import Message, _native, _always_bytes, MessageData, MessageMultiDict
 
 # This regex extracts & splits the host header into host and port.
 # Handles the edge case of IPv6 addresses containing colons.
@@ -224,45 +224,54 @@ class Request(Message):
 
     @property
     def query(self):
+        # type: () -> MessageMultiDict
         """
-        The request query string as an :py:class:`ODict` object.
-        None, if there is no query.
+        The request query string as an :py:class:`MessageMultiDict` object.
         """
+        return MessageMultiDict("query", self)
+
+    @property
+    def _query(self):
         _, _, _, _, query, _ = urllib.parse.urlparse(self.url)
-        if query:
-            return ODict(utils.urldecode(query))
-        return None
+        return tuple(utils.urldecode(query))
 
     @query.setter
-    def query(self, odict):
-        query = utils.urlencode(odict.lst)
+    def query(self, value):
+        query = utils.urlencode(value)
         scheme, netloc, path, params, _, fragment = urllib.parse.urlparse(self.url)
         _, _, _, self.path = utils.parse_url(
                 urllib.parse.urlunparse([scheme, netloc, path, params, query, fragment]))
 
     @property
     def cookies(self):
+        # type: () -> MessageMultiDict
         """
         The request cookies.
-        An empty :py:class:`ODict` object if the cookie monster ate them all.
+
+        An empty :py:class:`MessageMultiDict` object if the cookie monster ate them all.
         """
-        ret = ODict()
-        for i in self.headers.get_all("Cookie"):
-            ret.extend(cookies.parse_cookie_header(i))
-        return ret
+        return MessageMultiDict("cookies", self)
+
+    @property
+    def _cookies(self):
+        h = self.headers.get_all("Cookie")
+        return tuple(cookies.parse_cookie_headers(h))
 
     @cookies.setter
-    def cookies(self, odict):
-        self.headers["cookie"] = cookies.format_cookie_header(odict)
+    def cookies(self, value):
+        self.headers["cookie"] = cookies.format_cookie_header(value)
 
     @property
     def path_components(self):
         """
-        The URL's path components as a list of strings.
+        The URL's path components as a tuple of strings.
         Components are unquoted.
         """
         _, _, path, _, _, _ = urllib.parse.urlparse(self.url)
-        return [urllib.parse.unquote(i) for i in path.split("/") if i]
+        # This needs to be a tuple so that it's immutable.
+        # Otherwise, this would fail silently:
+        #   request.path_components.append("foo")
+        return tuple(urllib.parse.unquote(i) for i in path.split("/") if i)
 
     @path_components.setter
     def path_components(self, components):
@@ -309,34 +318,42 @@ class Request(Message):
     @property
     def urlencoded_form(self):
         """
-        The URL-encoded form data as an :py:class:`ODict` object.
-        None if there is no data or the content-type indicates non-form data.
+        The URL-encoded form data as an :py:class:`MessageMultiDict` object.
+        None if the content-type indicates non-form data.
         """
         is_valid_content_type = "application/x-www-form-urlencoded" in self.headers.get("content-type", "").lower()
-        if self.content and is_valid_content_type:
-            return ODict(utils.urldecode(self.content))
+        if is_valid_content_type:
+            return MessageMultiDict("urlencoded_form", self)
         return None
 
+    @property
+    def _urlencoded_form(self):
+        return tuple(utils.urldecode(self.content))
+
     @urlencoded_form.setter
-    def urlencoded_form(self, odict):
+    def urlencoded_form(self, value):
         """
         Sets the body to the URL-encoded form data, and adds the appropriate content-type header.
         This will overwrite the existing content if there is one.
         """
         self.headers["content-type"] = "application/x-www-form-urlencoded"
-        self.content = utils.urlencode(odict.lst)
+        self.content = utils.urlencode(value)
 
     @property
     def multipart_form(self):
         """
-        The multipart form data as an :py:class:`ODict` object.
-        None if there is no data or the content-type indicates non-form data.
+        The multipart form data as an :py:class:`MultipartFormDict` object.
+        None if the content-type indicates non-form data.
         """
         is_valid_content_type = "multipart/form-data" in self.headers.get("content-type", "").lower()
-        if self.content and is_valid_content_type:
-            return ODict(utils.multipartdecode(self.headers,self.content))
+        if is_valid_content_type:
+            return MessageMultiDict("multipart_form", self)
         return None
 
+    @property
+    def _multipart_form(self):
+        return utils.multipartdecode(self.headers, self.content)
+
     @multipart_form.setter
     def multipart_form(self, value):
         raise NotImplementedError()
diff --git a/netlib/http/response.py b/netlib/http/response.py
index 2f06149e..20074dca 100644
--- a/netlib/http/response.py
+++ b/netlib/http/response.py
@@ -70,6 +70,7 @@ class Response(Message):
     def reason(self, reason):
         self.data.reason = _always_bytes(reason)
 
+    # FIXME
     @property
     def cookies(self):
         """
@@ -88,6 +89,7 @@ class Response(Message):
                 ret.append([name, [value, attrs]])
         return ODict(ret)
 
+    # FIXME
     @cookies.setter
     def cookies(self, odict):
         values = []
diff --git a/netlib/multidict.py b/netlib/multidict.py
new file mode 100644
index 00000000..a7158bc5
--- /dev/null
+++ b/netlib/multidict.py
@@ -0,0 +1,163 @@
+from __future__ import absolute_import, print_function, division

+

+from abc import ABCMeta, abstractmethod

+

+from typing import Tuple

+

+try:

+    from collections.abc import MutableMapping

+except ImportError:  # pragma: no cover

+    from collections import MutableMapping  # Workaround for Python < 3.3

+

+import six

+

+from .utils import Serializable

+

+

+@six.add_metaclass(ABCMeta)

+class MultiDict(MutableMapping, Serializable):

+    def __init__(self, fields=None):

+

+        # it is important for us that .fields is immutable, so that we can easily

+        # detect changes to it.

+        self.fields = tuple(fields) if fields else tuple()  # type: Tuple[Tuple[bytes, bytes], ...]

+

+        for key, value in self.fields:

+            if not isinstance(key, bytes) or not isinstance(value, bytes):

+                raise TypeError("MultiDict fields must be bytes.")

+

+    def __repr__(self):

+        fields = tuple(

+            repr(field)

+            for field in self.fields

+        )

+        return "{cls}[{fields}]".format(

+            cls=type(self).__name__,

+            fields=", ".join(fields)

+        )

+

+    @staticmethod

+    @abstractmethod

+    def _reduce_values(values):

+        pass

+

+    @staticmethod

+    @abstractmethod

+    def _kconv(v):

+        pass

+

+    def __getitem__(self, key):

+        values = self.get_all(key)

+        if not values:

+            raise KeyError(key)

+        return self._reduce_values(values)

+

+    def __setitem__(self, key, value):

+        self.set_all(key, [value])

+

+    def __delitem__(self, key):

+        if key not in self:

+            raise KeyError(key)

+        key = self._kconv(key)

+        self.fields = tuple(

+            field for field in self.fields

+            if key != self._kconv(field[0])

+        )

+

+    def __iter__(self):

+        seen = set()

+        for key, _ in self.fields:

+            key_kconv = self._kconv(key)

+            if key_kconv not in seen:

+                seen.add(key_kconv)

+                yield key

+

+    def __len__(self):

+        return len(set(self._kconv(key) for key, _ in self.fields))

+

+    def __eq__(self, other):

+        if isinstance(other, MultiDict):

+            return self.fields == other.fields

+        return False

+

+    def __ne__(self, other):

+        return not self.__eq__(other)

+

+    def get_all(self, key):

+        """

+        Return the list of items for a given key.

+        If that key is not in the MultiDict,

+        the return value will be an empty list.

+        """

+        key = self._kconv(key)

+        return [

+            value

+            for k, value in self.fields

+            if self._kconv(k) == key

+            ]

+

+    def set_all(self, key, values):

+        """

+        Remove the old values for a key and add new ones.

+        """

+        key_kconv = self._kconv(key)

+

+        new_fields = []

+        for field in self.fields:

+            if self._kconv(field[0]) == key_kconv:

+                if values:

+                    new_fields.append(

+                        (key, values.pop(0))

+                    )

+            else:

+                new_fields.append(field)

+        while values:

+            new_fields.append(

+                (key, values.pop(0))

+            )

+        self.fields = tuple(new_fields)

+

+    def add(self, key, value):

+        self.insert(len(self.fields), key, value)

+

+    def insert(self, index, key, value):

+        item = (key, value)

+        self.fields = self.fields[:index] + (item,) + self.fields[index:]

+

+    def keys(self, multi=False):

+        return (

+            k

+            for k, _ in self.items(multi)

+        )

+

+    def values(self, multi=False):

+        return (

+            v

+            for _, v in self.items(multi)

+        )

+

+    def items(self, multi=False):

+        if multi:

+            return self.fields

+        else:

+            return super(MultiDict, self).items()

+

+    def to_dict(self):

+        d = {}

+        for key in self:

+            values = self.get_all(key)

+            if len(values) == 1:

+                d[key] = values[0]

+            else:

+                d[key] = values

+        return d

+

+    def get_state(self):

+        return self.fields

+

+    def set_state(self, state):

+        self.fields = tuple(tuple(x) for x in state)

+

+    @classmethod

+    def from_state(cls, state):

+        return cls(tuple(x) for x in state)

diff --git a/netlib/utils.py b/netlib/utils.py
index be2701a0..7499f71f 100644
--- a/netlib/utils.py
+++ b/netlib/utils.py
@@ -51,17 +51,6 @@ def always_bytes(unicode_or_bytes, *encode_args):
     return unicode_or_bytes
 
 
-def always_byte_args(*encode_args):
-    """Decorator that transparently encodes all arguments passed as unicode"""
-    def decorator(fun):
-        def _fun(*args, **kwargs):
-            args = [always_bytes(arg, *encode_args) for arg in args]
-            kwargs = {k: always_bytes(v, *encode_args) for k, v in six.iteritems(kwargs)}
-            return fun(*args, **kwargs)
-        return _fun
-    return decorator
-
-
 def native(s, *encoding_opts):
     """
     Convert :py:class:`bytes` or :py:class:`unicode` to the native
diff --git a/test/mitmproxy/test_examples.py b/test/mitmproxy/test_examples.py
index c401a6b9..d0a258e9 100644
--- a/test/mitmproxy/test_examples.py
+++ b/test/mitmproxy/test_examples.py
@@ -94,14 +94,22 @@ def test_modify_form():
     flow = tutils.tflow(req=netutils.treq(headers=form_header))
     with example("modify_form.py") as ex:
         ex.run("request", flow)
-        assert flow.request.urlencoded_form["mitmproxy"] == ["rocks"]
+        assert flow.request.urlencoded_form["mitmproxy"] == "rocks"
+
+        flow.request.headers["content-type"] = ""
+        ex.run("request", flow)
+        assert list(flow.request.urlencoded_form.items()) == [("foo","bar")]
 
 
 def test_modify_querystring():
     flow = tutils.tflow(req=netutils.treq(path="/search?q=term"))
     with example("modify_querystring.py") as ex:
         ex.run("request", flow)
-        assert flow.request.query["mitmproxy"] == ["rocks"]
+        assert flow.request.query["mitmproxy"] == "rocks"
+
+        flow.request.path = "/"
+        ex.run("request", flow)
+        assert flow.request.query["mitmproxy"] == "rocks"
 
 
 def test_modify_response_body():
diff --git a/test/mitmproxy/test_flow.py b/test/mitmproxy/test_flow.py
index b9c6a2f6..bf417423 100644
--- a/test/mitmproxy/test_flow.py
+++ b/test/mitmproxy/test_flow.py
@@ -1067,60 +1067,6 @@ class TestRequest:
         assert r.url == "https://address:22/path"
         assert r.pretty_url == "https://foo.com:22/path"
 
-    def test_path_components(self):
-        r = HTTPRequest.wrap(netlib.tutils.treq())
-        r.path = "/"
-        assert r.get_path_components() == []
-        r.path = "/foo/bar"
-        assert r.get_path_components() == ["foo", "bar"]
-        q = odict.ODict()
-        q["test"] = ["123"]
-        r.set_query(q)
-        assert r.get_path_components() == ["foo", "bar"]
-
-        r.set_path_components([])
-        assert r.get_path_components() == []
-        r.set_path_components(["foo"])
-        assert r.get_path_components() == ["foo"]
-        r.set_path_components(["/oo"])
-        assert r.get_path_components() == ["/oo"]
-        assert "%2F" in r.path
-
-    def test_getset_form_urlencoded(self):
-        d = odict.ODict([("one", "two"), ("three", "four")])
-        r = HTTPRequest.wrap(netlib.tutils.treq(content=netlib.utils.urlencode(d.lst)))
-        r.headers["content-type"] = "application/x-www-form-urlencoded"
-        assert r.get_form_urlencoded() == d
-
-        d = odict.ODict([("x", "y")])
-        r.set_form_urlencoded(d)
-        assert r.get_form_urlencoded() == d
-
-        r.headers["content-type"] = "foo"
-        assert not r.get_form_urlencoded()
-
-    def test_getset_query(self):
-        r = HTTPRequest.wrap(netlib.tutils.treq())
-        r.path = "/foo?x=y&a=b"
-        q = r.get_query()
-        assert q.lst == [("x", "y"), ("a", "b")]
-
-        r.path = "/"
-        q = r.get_query()
-        assert not q
-
-        r.path = "/?adsfa"
-        q = r.get_query()
-        assert q.lst == [("adsfa", "")]
-
-        r.path = "/foo?x=y&a=b"
-        assert r.get_query()
-        r.set_query(odict.ODict([]))
-        assert not r.get_query()
-        qv = odict.ODict([("a", "b"), ("c", "d")])
-        r.set_query(qv)
-        assert r.get_query() == qv
-
     def test_anticache(self):
         r = HTTPRequest.wrap(netlib.tutils.treq())
         r.headers = Headers()
diff --git a/test/mitmproxy/test_flow_export.py b/test/mitmproxy/test_flow_export.py
index 035f07b7..2b1f897c 100644
--- a/test/mitmproxy/test_flow_export.py
+++ b/test/mitmproxy/test_flow_export.py
@@ -21,7 +21,7 @@ def python_equals(testdata, text):
     assert clean_blanks(text).rstrip() == clean_blanks(d).rstrip()
 
 
-req_get = lambda: netlib.tutils.treq(method='GET', content='')
+req_get = lambda: netlib.tutils.treq(method='GET', content='', path=b"/")
 
 req_post = lambda: netlib.tutils.treq(method='POST', headers=None)
 
diff --git a/test/netlib/http/http1/test_read.py b/test/netlib/http/http1/test_read.py
index 90234070..d8106904 100644
--- a/test/netlib/http/http1/test_read.py
+++ b/test/netlib/http/http1/test_read.py
@@ -261,7 +261,7 @@ class TestReadHeaders(object):
             b"\r\n"
         )
         headers = self._read(data)
-        assert headers.fields == [[b"Header", b"one"], [b"Header2", b"two"]]
+        assert headers.fields == ((b"Header", b"one"), (b"Header2", b"two"))
 
     def test_read_multi(self):
         data = (
@@ -270,7 +270,7 @@ class TestReadHeaders(object):
             b"\r\n"
         )
         headers = self._read(data)
-        assert headers.fields == [[b"Header", b"one"], [b"Header", b"two"]]
+        assert headers.fields == ((b"Header", b"one"), (b"Header", b"two"))
 
     def test_read_continued(self):
         data = (
@@ -280,7 +280,7 @@ class TestReadHeaders(object):
             b"\r\n"
         )
         headers = self._read(data)
-        assert headers.fields == [[b"Header", b"one\r\n two"], [b"Header2", b"three"]]
+        assert headers.fields == ((b"Header", b"one\r\n two"), (b"Header2", b"three"))
 
     def test_read_continued_err(self):
         data = b"\tfoo: bar\r\n"
@@ -300,7 +300,7 @@ class TestReadHeaders(object):
     def test_read_empty_value(self):
         data = b"bar:"
         headers = self._read(data)
-        assert headers.fields == [[b"bar", b""]]
+        assert headers.fields == ((b"bar", b""),)
 
 def test_read_chunked():
     req = treq(content=None)
diff --git a/test/netlib/http/http2/test_connections.py b/test/netlib/http/http2/test_connections.py
index 7b003067..7d240c0e 100644
--- a/test/netlib/http/http2/test_connections.py
+++ b/test/netlib/http/http2/test_connections.py
@@ -312,7 +312,7 @@ class TestReadRequest(tservers.ServerTestBase):
         req = protocol.read_request(NotImplemented)
 
         assert req.stream_id
-        assert req.headers.fields == [[b':method', b'GET'], [b':path', b'/'], [b':scheme', b'https']]
+        assert req.headers.fields == ((b':method', b'GET'), (b':path', b'/'), (b':scheme', b'https'))
         assert req.content == b'foobar'
 
 
@@ -418,7 +418,7 @@ class TestReadResponse(tservers.ServerTestBase):
         assert resp.http_version == "HTTP/2.0"
         assert resp.status_code == 200
         assert resp.reason == ''
-        assert resp.headers.fields == [[b':status', b'200'], [b'etag', b'foobar']]
+        assert resp.headers.fields == ((b':status', b'200'), (b'etag', b'foobar'))
         assert resp.content == b'foobar'
         assert resp.timestamp_end
 
@@ -445,7 +445,7 @@ class TestReadEmptyResponse(tservers.ServerTestBase):
         assert resp.http_version == "HTTP/2.0"
         assert resp.status_code == 200
         assert resp.reason == ''
-        assert resp.headers.fields == [[b':status', b'200'], [b'etag', b'foobar']]
+        assert resp.headers.fields == ((b':status', b'200'), (b'etag', b'foobar'))
         assert resp.content == b''
 
 
diff --git a/test/netlib/http/test_cookies.py b/test/netlib/http/test_cookies.py
index da28850f..e2cee57f 100644
--- a/test/netlib/http/test_cookies.py
+++ b/test/netlib/http/test_cookies.py
@@ -128,10 +128,10 @@ def test_cookie_roundtrips():
     ]
     for s, lst in pairs:
         ret = cookies.parse_cookie_header(s)
-        assert ret.lst == lst
+        assert ret == lst
         s2 = cookies.format_cookie_header(ret)
         ret = cookies.parse_cookie_header(s2)
-        assert ret.lst == lst
+        assert ret == lst
 
 
 def test_parse_set_cookie_pairs():
diff --git a/test/netlib/http/test_headers.py b/test/netlib/http/test_headers.py
index 8c1db9dc..48d3b323 100644
--- a/test/netlib/http/test_headers.py
+++ b/test/netlib/http/test_headers.py
@@ -5,10 +5,10 @@ from netlib.tutils import raises
 class TestHeaders(object):
     def _2host(self):
         return Headers(
-            [
-                [b"Host", b"example.com"],
-                [b"host", b"example.org"]
-            ]
+            (
+                (b"Host", b"example.com"),
+                (b"host", b"example.org")
+            )
         )
 
     def test_init(self):
@@ -38,7 +38,7 @@ class TestHeaders(object):
         assert headers["Host"] == "example.com"
         assert headers["Accept"] == "text/plain"
 
-        with raises(ValueError):
+        with raises(TypeError):
             Headers([[b"Host", u"not-bytes"]])
 
     def test_getitem(self):
diff --git a/test/netlib/http/test_request.py b/test/netlib/http/test_request.py
index 7ed6bd0f..26593ee1 100644
--- a/test/netlib/http/test_request.py
+++ b/test/netlib/http/test_request.py
@@ -12,7 +12,7 @@ from .test_message import _test_decoded_attr, _test_passthrough_attr
 
 class TestRequestData(object):
     def test_init(self):
-        with raises(ValueError if six.PY2 else TypeError):
+        with raises(ValueError):
             treq(headers="foobar")
 
         assert isinstance(treq(headers=None).headers, Headers)
@@ -158,16 +158,17 @@ class TestRequestUtils(object):
 
     def test_get_query(self):
         request = treq()
-        assert request.query is None
+        assert not request.query
 
         request.url = "http://localhost:80/foo?bar=42"
-        assert request.query.lst == [("bar", "42")]
+        assert dict(request.query) == {"bar": "42"}
 
     def test_set_query(self):
-        request = treq(host=b"foo", headers = Headers(host=b"bar"))
-        request.query = ODict([])
-        assert request.host == "foo"
-        assert request.headers["host"] == "bar"
+        request = treq()
+        assert not request.query
+        request.query["foo"] = "bar"
+        assert request.query["foo"] == "bar"
+        assert request.path == "/path?foo=bar"
 
     def test_get_cookies_none(self):
         request = treq()
@@ -177,47 +178,50 @@ class TestRequestUtils(object):
     def test_get_cookies_single(self):
         request = treq()
         request.headers = Headers(cookie="cookiename=cookievalue")
-        result = request.cookies
-        assert len(result) == 1
-        assert result['cookiename'] == ['cookievalue']
+        assert len(request.cookies) == 1
+        assert request.cookies['cookiename'] == 'cookievalue'
 
     def test_get_cookies_double(self):
         request = treq()
         request.headers = Headers(cookie="cookiename=cookievalue;othercookiename=othercookievalue")
         result = request.cookies
         assert len(result) == 2
-        assert result['cookiename'] == ['cookievalue']
-        assert result['othercookiename'] == ['othercookievalue']
+        assert result['cookiename'] == 'cookievalue'
+        assert result['othercookiename'] == 'othercookievalue'
 
     def test_get_cookies_withequalsign(self):
         request = treq()
         request.headers = Headers(cookie="cookiename=coo=kievalue;othercookiename=othercookievalue")
         result = request.cookies
         assert len(result) == 2
-        assert result['cookiename'] == ['coo=kievalue']
-        assert result['othercookiename'] == ['othercookievalue']
+        assert result['cookiename'] == 'coo=kievalue'
+        assert result['othercookiename'] == 'othercookievalue'
 
     def test_set_cookies(self):
         request = treq()
         request.headers = Headers(cookie="cookiename=cookievalue")
         result = request.cookies
-        result["cookiename"] = ["foo"]
-        request.cookies = result
-        assert request.cookies["cookiename"] == ["foo"]
+        result["cookiename"] = "foo"
+        assert request.cookies["cookiename"] == "foo"
 
     def test_get_path_components(self):
         request = treq(path=b"/foo/bar")
-        assert request.path_components == ["foo", "bar"]
+        assert request.path_components == ("foo", "bar")
 
     def test_set_path_components(self):
-        request = treq(host=b"foo", headers = Headers(host=b"bar"))
+        request = treq()
         request.path_components = ["foo", "baz"]
         assert request.path == "/foo/baz"
+
         request.path_components = []
         assert request.path == "/"
-        request.query = ODict([])
-        assert request.host == "foo"
-        assert request.headers["host"] == "bar"
+
+        request.path_components = ["foo", "baz"]
+        request.query["hello"] = "hello"
+        assert request.path_components == ("foo", "baz")
+
+        request.path_components = ["abc"]
+        assert request.path == "/abc?hello=hello"
 
     def test_anticache(self):
         request = treq()
@@ -246,15 +250,15 @@ class TestRequestUtils(object):
         assert "gzip" in request.headers["Accept-Encoding"]
 
     def test_get_urlencoded_form(self):
-        request = treq(content="foobar")
+        request = treq(content="foobar=baz")
         assert request.urlencoded_form is None
 
         request.headers["Content-Type"] = "application/x-www-form-urlencoded"
-        assert request.urlencoded_form == ODict(utils.urldecode(request.content))
+        assert list(request.urlencoded_form.items()) == [("foobar", "baz")]
 
     def test_set_urlencoded_form(self):
         request = treq()
-        request.urlencoded_form = ODict([('foo', 'bar'), ('rab', 'oof')])
+        request.urlencoded_form = [('foo', 'bar'), ('rab', 'oof')]
         assert request.headers["Content-Type"] == "application/x-www-form-urlencoded"
         assert request.content
 
@@ -263,9 +267,4 @@ class TestRequestUtils(object):
         assert request.multipart_form is None
 
         request.headers["Content-Type"] = "multipart/form-data"
-        assert request.multipart_form == ODict(
-            utils.multipartdecode(
-                request.headers,
-                request.content
-            )
-        )
+        assert list(request.multipart_form.items()) == []
diff --git a/test/netlib/http/test_response.py b/test/netlib/http/test_response.py
index 5440176c..37273541 100644
--- a/test/netlib/http/test_response.py
+++ b/test/netlib/http/test_response.py
@@ -13,7 +13,7 @@ from .test_message import _test_passthrough_attr, _test_decoded_attr
 
 class TestResponseData(object):
     def test_init(self):
-        with raises(ValueError if six.PY2 else TypeError):
+        with raises(ValueError):
             tresp(headers="foobar")
 
         assert isinstance(tresp(headers=None).headers, Headers)