wip

18 files changed, 759 insertions, 846 deletions

diff --git a/netlib/encoding.py b/netlib/encoding.py
index f107eb5f..06830f2c 100644
--- a/netlib/encoding.py
+++ b/netlib/encoding.py
@@ -2,13 +2,13 @@
     Utility functions for decoding response bodies.
 """
 from __future__ import absolute_import
-import cStringIO
+from io import BytesIO
 import gzip
 import zlib
 
 __ALL__ = ["ENCODINGS"]
 
-ENCODINGS = set(["identity", "gzip", "deflate"])
+ENCODINGS = {"identity", "gzip", "deflate"}
 
 
 def decode(e, content):
@@ -42,7 +42,7 @@ def identity(content):
 
 
 def decode_gzip(content):
-    gfile = gzip.GzipFile(fileobj=cStringIO.StringIO(content))
+    gfile = gzip.GzipFile(fileobj=BytesIO(content))
     try:
         return gfile.read()
     except (IOError, EOFError):
@@ -50,7 +50,7 @@ def decode_gzip(content):
 
 
 def encode_gzip(content):
-    s = cStringIO.StringIO()
+    s = BytesIO()
     gf = gzip.GzipFile(fileobj=s, mode='wb')
     gf.write(content)
     gf.close()
diff --git a/netlib/exceptions.py b/netlib/exceptions.py
new file mode 100644
index 00000000..637be3df
--- /dev/null
+++ b/netlib/exceptions.py
@@ -0,0 +1,31 @@
+"""
+We try to be very hygienic regarding the exceptions we throw:
+Every Exception netlib raises shall be a subclass of NetlibException.
+
+
+See also: http://lucumr.pocoo.org/2014/10/16/on-error-handling/
+"""
+from __future__ import absolute_import, print_function, division
+
+
+class NetlibException(Exception):
+    """
+    Base class for all exceptions thrown by netlib.
+    """
+    def __init__(self, message=None):
+        super(NetlibException, self).__init__(message)
+
+
+class ReadDisconnect(object):
+    """Immediate EOF"""
+
+
+class HttpException(NetlibException):
+    pass
+
+
+class HttpReadDisconnect(HttpException, ReadDisconnect):
+    pass
+
+class HttpSyntaxException(HttpException):
+    pass
diff --git a/netlib/http/__init__.py b/netlib/http/__init__.py
index 9b4b0e6b..0b1a0bc5 100644
--- a/netlib/http/__init__.py
+++ b/netlib/http/__init__.py
@@ -1,2 +1,7 @@
-from exceptions import *
-from semantics import *
+from .models import Request, Response, Headers, CONTENT_MISSING
+from . import http1, http2
+
+__all__ = [
+    "Request", "Response", "Headers", "CONTENT_MISSING"
+    "http1", "http2"
+]
diff --git a/netlib/http/authentication.py b/netlib/http/authentication.py
index fe1f0d14..2055f843 100644
--- a/netlib/http/authentication.py
+++ b/netlib/http/authentication.py
@@ -19,8 +19,8 @@ def parse_http_basic_auth(s):
 
 
 def assemble_http_basic_auth(scheme, username, password):
-    v = binascii.b2a_base64(username + ":" + password)
-    return scheme + " " + v
+    v = binascii.b2a_base64(username + b":" + password)
+    return scheme + b" " + v
 
 
 class NullProxyAuth(object):
diff --git a/netlib/http/exceptions.py b/netlib/http/exceptions.py
deleted file mode 100644
index 8a2bbebc..00000000
--- a/netlib/http/exceptions.py
+++ /dev/null
@@ -1,9 +0,0 @@
-class HttpError(Exception):
-
-    def __init__(self, code, message):
-        super(HttpError, self).__init__(message)
-        self.code = code
-
-
-class HttpErrorConnClosed(HttpError):
-    pass
diff --git a/netlib/http/http1/__init__.py b/netlib/http/http1/__init__.py
index 6b5043af..4d223f97 100644
--- a/netlib/http/http1/__init__.py
+++ b/netlib/http/http1/__init__.py
@@ -1 +1,22 @@
-from protocol import *
+from .read import (
+    read_request, read_request_head,
+    read_response, read_response_head,
+    read_message_body, read_message_body_chunked,
+    connection_close,
+    expected_http_body_size,
+)
+from .assemble import (
+    assemble_request, assemble_request_head,
+    assemble_response, assemble_response_head,
+)
+
+
+__all__ = [
+    "read_request", "read_request_head",
+    "read_response", "read_response_head",
+    "read_message_body", "read_message_body_chunked",
+    "connection_close",
+    "expected_http_body_size",
+    "assemble_request", "assemble_request_head",
+    "assemble_response", "assemble_response_head",
+]
diff --git a/netlib/http/http1/assemble.py b/netlib/http/http1/assemble.py
new file mode 100644
index 00000000..a3269eed
--- /dev/null
+++ b/netlib/http/http1/assemble.py
@@ -0,0 +1,105 @@
+from __future__ import absolute_import, print_function, division
+
+from ... import utils
+from ...exceptions import HttpException
+from .. import CONTENT_MISSING
+
+
+def assemble_request(request):
+    if request.body == CONTENT_MISSING:
+        raise HttpException("Cannot assemble flow with CONTENT_MISSING")
+    head = assemble_request_head(request)
+    return head + request.body
+
+
+def assemble_request_head(request):
+    first_line = _assemble_request_line(request)
+    headers = _assemble_request_headers(request)
+    return b"%s\r\n%s\r\n" % (first_line, headers)
+
+
+def assemble_response(response):
+    if response.body == CONTENT_MISSING:
+        raise HttpException("Cannot assemble flow with CONTENT_MISSING")
+    head = assemble_response_head(response)
+    return head + response.body
+
+
+def assemble_response_head(response):
+    first_line = _assemble_response_line(response)
+    headers = _assemble_response_headers(response)
+    return b"%s\r\n%s\r\n" % (first_line, headers)
+
+
+
+
+def _assemble_request_line(request, form=None):
+    if form is None:
+        form = request.form_out
+    if form == "relative":
+        return b"%s %s %s" % (
+            request.method,
+            request.path,
+            request.httpversion
+        )
+    elif form == "authority":
+        return b"%s %s:%d %s" % (
+            request.method,
+            request.host,
+            request.port,
+            request.httpversion
+        )
+    elif form == "absolute":
+        return b"%s %s://%s:%s%s %s" % (
+            request.method,
+            request.scheme,
+            request.host,
+            request.port,
+            request.path,
+            request.httpversion
+        )
+    else:  # pragma: nocover
+        raise RuntimeError("Invalid request form")
+
+
+def _assemble_request_headers(request):
+    headers = request.headers.copy()
+    for k in request._headers_to_strip_off:
+        headers.pop(k, None)
+    if b"host" not in headers and request.scheme and request.host and request.port:
+        headers[b"Host"] = utils.hostport(
+            request.scheme,
+            request.host,
+            request.port
+        )
+
+    # If content is defined (i.e. not None or CONTENT_MISSING), we always
+    # add a content-length header.
+    if request.body or request.body == b"":
+        headers[b"Content-Length"] = str(len(request.body)).encode("ascii")
+
+    return str(headers)
+
+
+def _assemble_response_line(response):
+    return b"%s %s %s" % (
+        response.httpversion,
+        response.status_code,
+        response.msg,
+    )
+
+
+def _assemble_response_headers(response, preserve_transfer_encoding=False):
+    # TODO: Remove preserve_transfer_encoding
+    headers = response.headers.copy()
+    for k in response._headers_to_strip_off:
+        headers.pop(k, None)
+    if not preserve_transfer_encoding:
+        headers.pop(b"Transfer-Encoding", None)
+
+    # If body is defined (i.e. not None or CONTENT_MISSING), we always
+    # add a content-length header.
+    if response.body or response.body == b"":
+        headers[b"Content-Length"] = str(len(response.body)).encode("ascii")
+
+    return bytes(headers)
diff --git a/netlib/http/http1/protocol.py b/netlib/http/http1/protocol.py
deleted file mode 100644
index cf1dffa3..00000000
--- a/netlib/http/http1/protocol.py
+++ /dev/null
@@ -1,586 +0,0 @@
-from __future__ import (absolute_import, print_function, division)
-import string
-import sys
-import time
-
-from ... import utils, tcp, http
-from .. import semantics, Headers
-from ..exceptions import *
-
-
-class TCPHandler(object):
-
-    def __init__(self, rfile, wfile=None):
-        self.rfile = rfile
-        self.wfile = wfile
-
-
-class HTTP1Protocol(semantics.ProtocolMixin):
-
-    ALPN_PROTO_HTTP1 = 'http/1.1'
-
-    def __init__(self, tcp_handler=None, rfile=None, wfile=None):
-        self.tcp_handler = tcp_handler or TCPHandler(rfile, wfile)
-
-    def read_request(
-        self,
-        include_body=True,
-        body_size_limit=None,
-        allow_empty=False,
-    ):
-        """
-        Parse an HTTP request from a file stream
-
-        Args:
-            include_body (bool): Read response body as well
-            body_size_limit (bool): Maximum body size
-            wfile (file): If specified, HTTP Expect headers are handled
-            automatically, by writing a HTTP 100 CONTINUE response to the stream.
-
-        Returns:
-            Request: The HTTP request
-
-        Raises:
-            HttpError: If the input is invalid.
-        """
-        timestamp_start = time.time()
-        if hasattr(self.tcp_handler.rfile, "reset_timestamps"):
-            self.tcp_handler.rfile.reset_timestamps()
-
-        httpversion, host, port, scheme, method, path, headers, body = (
-            None, None, None, None, None, None, None, None)
-
-        request_line = self._get_request_line()
-        if not request_line:
-            if allow_empty:
-                return http.EmptyRequest()
-            else:
-                raise tcp.NetLibDisconnect()
-
-        request_line_parts = self._parse_init(request_line)
-        if not request_line_parts:
-            raise HttpError(
-                400,
-                "Bad HTTP request line: %s" % repr(request_line)
-            )
-        method, path, httpversion = request_line_parts
-
-        if path == '*' or path.startswith("/"):
-            form_in = "relative"
-            if not utils.isascii(path):
-                raise HttpError(
-                    400,
-                    "Bad HTTP request line: %s" % repr(request_line)
-                )
-        elif method == 'CONNECT':
-            form_in = "authority"
-            r = self._parse_init_connect(request_line)
-            if not r:
-                raise HttpError(
-                    400,
-                    "Bad HTTP request line: %s" % repr(request_line)
-                )
-            host, port, httpversion = r
-            path = None
-        else:
-            form_in = "absolute"
-            r = self._parse_init_proxy(request_line)
-            if not r:
-                raise HttpError(
-                    400,
-                    "Bad HTTP request line: %s" % repr(request_line)
-                )
-            _, scheme, host, port, path, _ = r
-
-        headers = self.read_headers()
-        if headers is None:
-            raise HttpError(400, "Invalid headers")
-
-        expect_header = headers.get("expect", "").lower()
-        if expect_header == "100-continue" and httpversion == (1, 1):
-            self.tcp_handler.wfile.write(
-                'HTTP/1.1 100 Continue\r\n'
-                '\r\n'
-            )
-            self.tcp_handler.wfile.flush()
-            del headers['expect']
-
-        if include_body:
-            body = self.read_http_body(
-                headers,
-                body_size_limit,
-                method,
-                None,
-                True
-            )
-
-        if hasattr(self.tcp_handler.rfile, "first_byte_timestamp"):
-            # more accurate timestamp_start
-            timestamp_start = self.tcp_handler.rfile.first_byte_timestamp
-
-        timestamp_end = time.time()
-
-        return http.Request(
-            form_in,
-            method,
-            scheme,
-            host,
-            port,
-            path,
-            httpversion,
-            headers,
-            body,
-            timestamp_start,
-            timestamp_end,
-        )
-
-    def read_response(
-        self,
-        request_method,
-        body_size_limit=None,
-        include_body=True,
-    ):
-        """
-            Returns an http.Response
-
-            By default, both response header and body are read.
-            If include_body=False is specified, body may be one of the
-            following:
-            - None, if the response is technically allowed to have a response body
-            - "", if the response must not have a response body (e.g. it's a
-            response to a HEAD request)
-        """
-        timestamp_start = time.time()
-        if hasattr(self.tcp_handler.rfile, "reset_timestamps"):
-            self.tcp_handler.rfile.reset_timestamps()
-
-        line = self.tcp_handler.rfile.readline()
-        # Possible leftover from previous message
-        if line == "\r\n" or line == "\n":
-            line = self.tcp_handler.rfile.readline()
-        if not line:
-            raise HttpErrorConnClosed(502, "Server disconnect.")
-        parts = self.parse_response_line(line)
-        if not parts:
-            raise HttpError(502, "Invalid server response: %s" % repr(line))
-        proto, code, msg = parts
-        httpversion = self._parse_http_protocol(proto)
-        if httpversion is None:
-            raise HttpError(502, "Invalid HTTP version in line: %s" % repr(proto))
-        headers = self.read_headers()
-        if headers is None:
-            raise HttpError(502, "Invalid headers.")
-
-        if include_body:
-            body = self.read_http_body(
-                headers,
-                body_size_limit,
-                request_method,
-                code,
-                False
-            )
-        else:
-            # if include_body==False then a None body means the body should be
-            # read separately
-            body = None
-
-        if hasattr(self.tcp_handler.rfile, "first_byte_timestamp"):
-            # more accurate timestamp_start
-            timestamp_start = self.tcp_handler.rfile.first_byte_timestamp
-
-        if include_body:
-            timestamp_end = time.time()
-        else:
-            timestamp_end = None
-
-        return http.Response(
-            httpversion,
-            code,
-            msg,
-            headers,
-            body,
-            timestamp_start=timestamp_start,
-            timestamp_end=timestamp_end,
-        )
-
-    def assemble_request(self, request):
-        assert isinstance(request, semantics.Request)
-
-        if request.body == semantics.CONTENT_MISSING:
-            raise http.HttpError(
-                502,
-                "Cannot assemble flow with CONTENT_MISSING"
-            )
-        first_line = self._assemble_request_first_line(request)
-        headers = self._assemble_request_headers(request)
-        return "%s\r\n%s\r\n%s" % (first_line, headers, request.body)
-
-    def assemble_response(self, response):
-        assert isinstance(response, semantics.Response)
-
-        if response.body == semantics.CONTENT_MISSING:
-            raise http.HttpError(
-                502,
-                "Cannot assemble flow with CONTENT_MISSING"
-            )
-        first_line = self._assemble_response_first_line(response)
-        headers = self._assemble_response_headers(response)
-        return "%s\r\n%s\r\n%s" % (first_line, headers, response.body)
-
-    def read_headers(self):
-        """
-            Read a set of headers.
-            Stop once a blank line is reached.
-
-            Return a Header object, or None if headers are invalid.
-        """
-        ret = []
-        while True:
-            line = self.tcp_handler.rfile.readline()
-            if not line or line == '\r\n' or line == '\n':
-                break
-            if line[0] in ' \t':
-                if not ret:
-                    return None
-                # continued header
-                ret[-1][1] = ret[-1][1] + '\r\n ' + line.strip()
-            else:
-                i = line.find(':')
-                # We're being liberal in what we accept, here.
-                if i > 0:
-                    name = line[:i]
-                    value = line[i + 1:].strip()
-                    ret.append([name, value])
-                else:
-                    return None
-        return Headers(ret)
-
-
-    def read_http_body(self, *args, **kwargs):
-        return "".join(self.read_http_body_chunked(*args, **kwargs))
-
-
-    def read_http_body_chunked(
-        self,
-        headers,
-        limit,
-        request_method,
-        response_code,
-        is_request,
-        max_chunk_size=None
-    ):
-        """
-            Read an HTTP message body:
-                headers: A Header object
-                limit: Size limit.
-                is_request: True if the body to read belongs to a request, False
-                otherwise
-        """
-        if max_chunk_size is None:
-            max_chunk_size = limit or sys.maxsize
-
-        expected_size = self.expected_http_body_size(
-            headers, is_request, request_method, response_code
-        )
-
-        if expected_size is None:
-            if self.has_chunked_encoding(headers):
-                # Python 3: yield from
-                for x in self._read_chunked(limit, is_request):
-                    yield x
-            else:  # pragma: nocover
-                raise HttpError(
-                    400 if is_request else 502,
-                    "Content-Length unknown but no chunked encoding"
-                )
-        elif expected_size >= 0:
-            if limit is not None and expected_size > limit:
-                raise HttpError(
-                    400 if is_request else 509,
-                    "HTTP Body too large. Limit is %s, content-length was %s" % (
-                        limit, expected_size
-                    )
-                )
-            bytes_left = expected_size
-            while bytes_left:
-                chunk_size = min(bytes_left, max_chunk_size)
-                content = self.tcp_handler.rfile.read(chunk_size)
-                yield content
-                bytes_left -= chunk_size
-        else:
-            bytes_left = limit or -1
-            while bytes_left:
-                chunk_size = min(bytes_left, max_chunk_size)
-                content = self.tcp_handler.rfile.read(chunk_size)
-                if not content:
-                    return
-                yield content
-                bytes_left -= chunk_size
-            not_done = self.tcp_handler.rfile.read(1)
-            if not_done:
-                raise HttpError(
-                    400 if is_request else 509,
-                    "HTTP Body too large. Limit is %s," % limit
-                )
-
-    @classmethod
-    def expected_http_body_size(
-        self,
-        headers,
-        is_request,
-        request_method,
-        response_code,
-    ):
-        """
-            Returns the expected body length:
-             - a positive integer, if the size is known in advance
-             - None, if the size in unknown in advance (chunked encoding or invalid
-             data)
-             - -1, if all data should be read until end of stream.
-
-            May raise HttpError.
-        """
-        # Determine response size according to
-        # http://tools.ietf.org/html/rfc7230#section-3.3
-        if request_method:
-            request_method = request_method.upper()
-
-        if (not is_request and (
-                request_method == "HEAD" or
-                (request_method == "CONNECT" and response_code == 200) or
-                response_code in [204, 304] or
-                100 <= response_code <= 199)):
-            return 0
-        if self.has_chunked_encoding(headers):
-            return None
-        if "content-length" in headers:
-            try:
-                size = int(headers["content-length"])
-                if size < 0:
-                    raise ValueError()
-                return size
-            except ValueError:
-                return None
-        if is_request:
-            return 0
-        return -1
-
-
-    @classmethod
-    def has_chunked_encoding(self, headers):
-        return "chunked" in headers.get("transfer-encoding", "").lower()
-
-
-    def _get_request_line(self):
-        """
-            Get a line, possibly preceded by a blank.
-        """
-        line = self.tcp_handler.rfile.readline()
-        if line == "\r\n" or line == "\n":
-            # Possible leftover from previous message
-            line = self.tcp_handler.rfile.readline()
-        return line
-
-    def _read_chunked(self, limit, is_request):
-        """
-            Read a chunked HTTP body.
-
-            May raise HttpError.
-        """
-        # FIXME: Should check if chunked is the final encoding in the headers
-        # http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-16#section-3.3
-        # 3.3 2.
-        total = 0
-        code = 400 if is_request else 502
-        while True:
-            line = self.tcp_handler.rfile.readline(128)
-            if line == "":
-                raise HttpErrorConnClosed(code, "Connection closed prematurely")
-            if line != '\r\n' and line != '\n':
-                try:
-                    length = int(line, 16)
-                except ValueError:
-                    raise HttpError(
-                        code,
-                        "Invalid chunked encoding length: %s" % line
-                    )
-                total += length
-                if limit is not None and total > limit:
-                    msg = "HTTP Body too large. Limit is %s," \
-                          " chunked content longer than %s" % (limit, total)
-                    raise HttpError(code, msg)
-                chunk = self.tcp_handler.rfile.read(length)
-                suffix = self.tcp_handler.rfile.readline(5)
-                if suffix != '\r\n':
-                    raise HttpError(code, "Malformed chunked body")
-                if length == 0:
-                    return
-                yield chunk
-
-    @classmethod
-    def _parse_http_protocol(self, line):
-        """
-            Parse an HTTP protocol declaration.
-            Returns a (major, minor) tuple, or None.
-        """
-        if not line.startswith("HTTP/"):
-            return None
-        _, version = line.split('/', 1)
-        if "." not in version:
-            return None
-        major, minor = version.split('.', 1)
-        try:
-            major = int(major)
-            minor = int(minor)
-        except ValueError:
-            return None
-        return major, minor
-
-    @classmethod
-    def _parse_init(self, line):
-        try:
-            method, url, protocol = string.split(line)
-        except ValueError:
-            return None
-        httpversion = self._parse_http_protocol(protocol)
-        if not httpversion:
-            return None
-        if not utils.isascii(method):
-            return None
-        return method, url, httpversion
-
-    @classmethod
-    def _parse_init_connect(self, line):
-        """
-            Returns (host, port, httpversion) if line is a valid CONNECT line.
-            http://tools.ietf.org/html/draft-luotonen-web-proxy-tunneling-01 section 3.1
-        """
-        v = self._parse_init(line)
-        if not v:
-            return None
-        method, url, httpversion = v
-
-        if method.upper() != 'CONNECT':
-            return None
-        try:
-            host, port = url.split(":")
-        except ValueError:
-            return None
-        try:
-            port = int(port)
-        except ValueError:
-            return None
-        if not utils.is_valid_port(port):
-            return None
-        if not utils.is_valid_host(host):
-            return None
-        return host, port, httpversion
-
-    @classmethod
-    def _parse_init_proxy(self, line):
-        v = self._parse_init(line)
-        if not v:
-            return None
-        method, url, httpversion = v
-
-        parts = utils.parse_url(url)
-        if not parts:
-            return None
-        scheme, host, port, path = parts
-        return method, scheme, host, port, path, httpversion
-
-    @classmethod
-    def _parse_init_http(self, line):
-        """
-            Returns (method, url, httpversion)
-        """
-        v = self._parse_init(line)
-        if not v:
-            return None
-        method, url, httpversion = v
-        if not utils.isascii(url):
-            return None
-        if not (url.startswith("/") or url == "*"):
-            return None
-        return method, url, httpversion
-
-    @classmethod
-    def connection_close(self, httpversion, headers):
-        """
-            Checks the message to see if the client connection should be closed
-            according to RFC 2616 Section 8.1 Note that a connection should be
-            closed as well if the response has been read until end of the stream.
-        """
-        # At first, check if we have an explicit Connection header.
-        if "connection" in headers:
-            toks = utils.get_header_tokens(headers, "connection")
-            if "close" in toks:
-                return True
-            elif "keep-alive" in toks:
-                return False
-
-        # If we don't have a Connection header, HTTP 1.1 connections are assumed to
-        # be persistent
-        return httpversion != (1, 1)
-
-    @classmethod
-    def parse_response_line(self, line):
-        parts = line.strip().split(" ", 2)
-        if len(parts) == 2:  # handle missing message gracefully
-            parts.append("")
-        if len(parts) != 3:
-            return None
-        proto, code, msg = parts
-        try:
-            code = int(code)
-        except ValueError:
-            return None
-        return (proto, code, msg)
-
-    @classmethod
-    def _assemble_request_first_line(self, request):
-        return request.legacy_first_line()
-
-    def _assemble_request_headers(self, request):
-        headers = request.headers.copy()
-        for k in request._headers_to_strip_off:
-            headers.pop(k, None)
-        if 'host' not in headers and request.scheme and request.host and request.port:
-            headers["Host"] = utils.hostport(
-                request.scheme,
-                request.host,
-                request.port
-            )
-
-        # If content is defined (i.e. not None or CONTENT_MISSING), we always
-        # add a content-length header.
-        if request.body or request.body == "":
-            headers["Content-Length"] = str(len(request.body))
-
-        return str(headers)
-
-    def _assemble_response_first_line(self, response):
-        return 'HTTP/%s.%s %s %s' % (
-            response.httpversion[0],
-            response.httpversion[1],
-            response.status_code,
-            response.msg,
-        )
-
-    def _assemble_response_headers(
-        self,
-        response,
-        preserve_transfer_encoding=False,
-    ):
-        headers = response.headers.copy()
-        for k in response._headers_to_strip_off:
-            headers.pop(k, None)
-        if not preserve_transfer_encoding:
-            headers.pop('Transfer-Encoding', None)
-
-        # If body is defined (i.e. not None or CONTENT_MISSING), we always
-        # add a content-length header.
-        if response.body or response.body == "":
-            headers["Content-Length"] = str(len(response.body))
-
-        return str(headers)
diff --git a/netlib/http/http1/read.py b/netlib/http/http1/read.py
new file mode 100644
index 00000000..573bc739
--- /dev/null
+++ b/netlib/http/http1/read.py
@@ -0,0 +1,346 @@
+from __future__ import absolute_import, print_function, division
+import time
+import sys
+import re
+
+from ... import utils
+from ...exceptions import HttpReadDisconnect, HttpSyntaxException, HttpException
+from .. import Request, Response, Headers
+
+ALPN_PROTO_HTTP1 = 'http/1.1'
+
+
+def read_request(rfile, body_size_limit=None):
+    request = read_request_head(rfile)
+    request.body = read_message_body(rfile, request, limit=body_size_limit)
+    request.timestamp_end = time.time()
+    return request
+
+
+def read_request_head(rfile):
+    """
+    Parse an HTTP request head (request line + headers) from an input stream
+
+    Args:
+        rfile: The input stream
+        body_size_limit (bool): Maximum body size
+
+    Returns:
+        The HTTP request object
+
+    Raises:
+        HttpReadDisconnect: If no bytes can be read from rfile.
+        HttpSyntaxException: If the input is invalid.
+        HttpException: A different error occured.
+    """
+    timestamp_start = time.time()
+    if hasattr(rfile, "reset_timestamps"):
+        rfile.reset_timestamps()
+
+    form, method, scheme, host, port, path, http_version = _read_request_line(rfile)
+    headers = _read_headers(rfile)
+
+    if hasattr(rfile, "first_byte_timestamp"):
+        # more accurate timestamp_start
+        timestamp_start = rfile.first_byte_timestamp
+
+    return Request(
+        form, method, scheme, host, port, path, http_version, headers, None, timestamp_start
+    )
+
+
+def read_response(rfile, request, body_size_limit=None):
+    response = read_response_head(rfile)
+    response.body = read_message_body(rfile, request, response, body_size_limit)
+    response.timestamp_end = time.time()
+    return response
+
+
+def read_response_head(rfile):
+    timestamp_start = time.time()
+    if hasattr(rfile, "reset_timestamps"):
+        rfile.reset_timestamps()
+
+    http_version, status_code, message = _read_response_line(rfile)
+    headers = _read_headers(rfile)
+
+    if hasattr(rfile, "first_byte_timestamp"):
+        # more accurate timestamp_start
+        timestamp_start = rfile.first_byte_timestamp
+
+    return Response(
+        http_version,
+        status_code,
+        message,
+        headers,
+        None,
+        timestamp_start
+    )
+
+
+def read_message_body(*args, **kwargs):
+    chunks = read_message_body_chunked(*args, **kwargs)
+    return b"".join(chunks)
+
+
+def read_message_body_chunked(rfile, request, response=None, limit=None, max_chunk_size=None):
+    """
+        Read an HTTP message body:
+
+        Args:
+            If a request body should be read, only request should be passed.
+            If a response body should be read, both request and response should be passed.
+
+        Raises:
+            HttpException
+    """
+    if not response:
+        headers = request.headers
+        response_code = None
+        is_request = True
+    else:
+        headers = response.headers
+        response_code = response.status_code
+        is_request = False
+
+    if not limit or limit < 0:
+        limit = sys.maxsize
+    if not max_chunk_size:
+        max_chunk_size = limit
+
+    expected_size = expected_http_body_size(
+        headers, is_request, request.method, response_code
+    )
+
+    if expected_size is None:
+        for x in _read_chunked(rfile, limit):
+            yield x
+    elif expected_size >= 0:
+        if limit is not None and expected_size > limit:
+            raise HttpException(
+                "HTTP Body too large. "
+                "Limit is {}, content length was advertised as {}".format(limit, expected_size)
+            )
+        bytes_left = expected_size
+        while bytes_left:
+            chunk_size = min(bytes_left, max_chunk_size)
+            content = rfile.read(chunk_size)
+            yield content
+            bytes_left -= chunk_size
+    else:
+        bytes_left = limit
+        while bytes_left:
+            chunk_size = min(bytes_left, max_chunk_size)
+            content = rfile.read(chunk_size)
+            if not content:
+                return
+            yield content
+            bytes_left -= chunk_size
+        not_done = rfile.read(1)
+        if not_done:
+            raise HttpException("HTTP body too large. Limit is {}.".format(limit))
+
+
+def connection_close(http_version, headers):
+    """
+        Checks the message to see if the client connection should be closed
+        according to RFC 2616 Section 8.1.
+    """
+    # At first, check if we have an explicit Connection header.
+    if b"connection" in headers:
+        toks = utils.get_header_tokens(headers, "connection")
+        if b"close" in toks:
+            return True
+        elif b"keep-alive" in toks:
+            return False
+
+    # If we don't have a Connection header, HTTP 1.1 connections are assumed to
+    # be persistent
+    return http_version != (1, 1)
+
+
+def expected_http_body_size(
+        headers,
+        is_request,
+        request_method,
+        response_code,
+):
+    """
+        Returns the expected body length:
+         - a positive integer, if the size is known in advance
+         - None, if the size in unknown in advance (chunked encoding)
+         - -1, if all data should be read until end of stream.
+
+        Raises:
+            HttpSyntaxException, if the content length header is invalid
+    """
+    # Determine response size according to
+    # http://tools.ietf.org/html/rfc7230#section-3.3
+    if request_method:
+        request_method = request_method.upper()
+
+    is_empty_response = (not is_request and (
+        request_method == b"HEAD" or
+        100 <= response_code <= 199 or
+        (response_code == 200 and request_method == b"CONNECT") or
+        response_code in (204, 304)
+    ))
+
+    if is_empty_response:
+        return 0
+    if is_request and headers.get(b"expect", b"").lower() == b"100-continue":
+        return 0
+    if b"chunked" in headers.get(b"transfer-encoding", b"").lower():
+        return None
+    if b"content-length" in headers:
+        try:
+            size = int(headers[b"content-length"])
+            if size < 0:
+                raise ValueError()
+            return size
+        except ValueError:
+            raise HttpSyntaxException("Unparseable Content Length")
+    if is_request:
+        return 0
+    return -1
+
+
+def _get_first_line(rfile):
+    line = rfile.readline()
+    if line == b"\r\n" or line == b"\n":
+        # Possible leftover from previous message
+        line = rfile.readline()
+    if not line:
+        raise HttpReadDisconnect()
+    return line
+
+
+def _read_request_line(rfile):
+    line = _get_first_line(rfile)
+
+    try:
+        method, path, http_version = line.strip().split(b" ")
+
+        if path == b"*" or path.startswith(b"/"):
+            form = "relative"
+            path.decode("ascii")  # should not raise a ValueError
+            scheme, host, port = None, None, None
+        elif method == b"CONNECT":
+            form = "authority"
+            host, port = _parse_authority_form(path)
+            scheme, path = None, None
+        else:
+            form = "absolute"
+            scheme, host, port, path = utils.parse_url(path)
+
+    except ValueError:
+        raise HttpSyntaxException("Bad HTTP request line: {}".format(line))
+
+    return form, method, scheme, host, port, path, http_version
+
+
+def _parse_authority_form(hostport):
+    """
+        Returns (host, port) if hostport is a valid authority-form host specification.
+        http://tools.ietf.org/html/draft-luotonen-web-proxy-tunneling-01 section 3.1
+
+        Raises:
+            ValueError, if the input is malformed
+    """
+    try:
+        host, port = hostport.split(b":")
+        port = int(port)
+        if not utils.is_valid_host(host) or not utils.is_valid_port(port):
+            raise ValueError()
+    except ValueError:
+        raise ValueError("Invalid host specification: {}".format(hostport))
+
+    return host, port
+
+
+def _read_response_line(rfile):
+    line = _get_first_line(rfile)
+
+    try:
+
+        parts = line.strip().split(b" ")
+        if len(parts) == 2:  # handle missing message gracefully
+            parts.append(b"")
+
+        http_version, status_code, message = parts
+        status_code = int(status_code)
+        _check_http_version(http_version)
+
+    except ValueError:
+        raise HttpSyntaxException("Bad HTTP response line: {}".format(line))
+
+    return http_version, status_code, message
+
+
+def _check_http_version(http_version):
+    if not re.match(rb"^HTTP/\d\.\d$", http_version):
+        raise HttpSyntaxException("Unknown HTTP version: {}".format(http_version))
+
+
+def _read_headers(rfile):
+    """
+        Read a set of headers.
+        Stop once a blank line is reached.
+
+        Returns:
+            A headers object
+
+        Raises:
+            HttpSyntaxException
+    """
+    ret = []
+    while True:
+        line = rfile.readline()
+        if not line or line == b"\r\n" or line == b"\n":
+            break
+        if line[0] in b" \t":
+            if not ret:
+                raise HttpSyntaxException("Invalid headers")
+            # continued header
+            ret[-1][1] = ret[-1][1] + b'\r\n ' + line.strip()
+        else:
+            try:
+                name, value = line.split(b":", 1)
+                value = value.strip()
+                ret.append([name, value])
+            except ValueError:
+                raise HttpSyntaxException("Invalid headers")
+    return Headers(ret)
+
+
+def _read_chunked(rfile, limit):
+    """
+    Read a HTTP body with chunked transfer encoding.
+
+    Args:
+        rfile: the input file
+        limit: A positive integer
+    """
+    total = 0
+    while True:
+        line = rfile.readline(128)
+        if line == b"":
+            raise HttpException("Connection closed prematurely")
+        if line != b"\r\n" and line != b"\n":
+            try:
+                length = int(line, 16)
+            except ValueError:
+                raise HttpSyntaxException("Invalid chunked encoding length: {}".format(line))
+            total += length
+            if total > limit:
+                raise HttpException(
+                    "HTTP Body too large. Limit is {}, "
+                    "chunked content longer than {}".format(limit, total)
+                )
+            chunk = rfile.read(length)
+            suffix = rfile.readline(5)
+            if suffix != b"\r\n":
+                raise HttpSyntaxException("Malformed chunked body")
+            if length == 0:
+                return
+            yield chunk
diff --git a/netlib/http/http2/__init__.py b/netlib/http/http2/__init__.py
index 5acf7696..e69de29b 100644
--- a/netlib/http/http2/__init__.py
+++ b/netlib/http/http2/__init__.py
@@ -1,2 +0,0 @@
-from frame import *
-from protocol import *
diff --git a/netlib/http/http2/protocol.py b/netlib/http/http2/connections.py
index b6d376d3..b6d376d3 100644
--- a/netlib/http/http2/protocol.py
+++ b/netlib/http/http2/connections.py
diff --git a/netlib/http/http2/frame.py b/netlib/http/http2/frames.py
index b36b3adf..b36b3adf 100644
--- a/netlib/http/http2/frame.py
+++ b/netlib/http/http2/frames.py
diff --git a/netlib/http/semantics.py b/netlib/http/models.py
index 5bb098a7..bd5863b1 100644
--- a/netlib/http/semantics.py
+++ b/netlib/http/models.py
@@ -1,20 +1,25 @@
-from __future__ import (absolute_import, print_function, division)
-import UserDict
+from __future__ import absolute_import, print_function, division
 import copy
-import urllib
-import urlparse
 
-from .. import odict
-from . import cookies, exceptions
-from netlib import utils, encoding
+from ..odict import ODict
+from .. import utils, encoding
+from ..utils import always_bytes, always_byte_args
+from . import cookies
 
-HDR_FORM_URLENCODED = "application/x-www-form-urlencoded"
-HDR_FORM_MULTIPART = "multipart/form-data"
+import six
+from six.moves import urllib
+try:
+    from collections import MutableMapping
+except ImportError:
+    from collections.abc import MutableMapping
+
+HDR_FORM_URLENCODED = b"application/x-www-form-urlencoded"
+HDR_FORM_MULTIPART = b"multipart/form-data"
 
 CONTENT_MISSING = 0
 
 
-class Headers(object, UserDict.DictMixin):
+class Headers(MutableMapping, object):
     """
     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.
@@ -62,10 +67,12 @@ class Headers(object, UserDict.DictMixin):
         For use with the "Set-Cookie" header, see :py:meth:`get_all`.
     """
 
+    @always_byte_args("ascii")
     def __init__(self, fields=None, **headers):
         """
         Args:
-            fields: (optional) list of ``(name, value)`` header tuples, e.g. ``[("Host","example.com")]``
+            fields: (optional) list of ``(name, value)`` header tuples,
+                e.g. ``[("Host","example.com")]``. All names and values must be bytes.
             **headers: Additional headers to set. Will overwrite existing values from `fields`.
                 For convenience, underscores in header names will be transformed to dashes -
                 this behaviour does not extend to other methods.
@@ -76,21 +83,25 @@ class Headers(object, UserDict.DictMixin):
 
         # content_type -> content-type
         headers = {
-            name.replace("_", "-"): value
-            for name, value in headers.iteritems()
+            name.encode("ascii").replace(b"_", b"-"): value
+            for name, value in six.iteritems(headers)
         }
         self.update(headers)
 
-    def __str__(self):
-        return "\r\n".join(": ".join(field) for field in self.fields) + "\r\n"
+    def __bytes__(self):
+        return b"\r\n".join(b": ".join(field) for field in self.fields) + b"\r\n"
+
+    if six.PY2:
+        __str__ = __bytes__
 
+    @always_byte_args("ascii")
     def __getitem__(self, name):
         values = self.get_all(name)
         if not values:
             raise KeyError(name)
-        else:
-            return ", ".join(values)
+        return b", ".join(values)
 
+    @always_byte_args("ascii")
     def __setitem__(self, name, value):
         idx = self._index(name)
 
@@ -101,6 +112,7 @@ class Headers(object, UserDict.DictMixin):
         else:
             self.fields.append([name, value])
 
+    @always_byte_args("ascii")
     def __delitem__(self, name):
         if name not in self:
             raise KeyError(name)
@@ -110,6 +122,19 @@ class Headers(object, UserDict.DictMixin):
             if name != field[0].lower()
         ]
 
+    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 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):
@@ -117,16 +142,6 @@ class Headers(object, UserDict.DictMixin):
                 return i
         return None
 
-    def keys(self):
-        seen = set()
-        names = []
-        for name, _ in self.fields:
-            name_lower = name.lower()
-            if name_lower not in seen:
-                seen.add(name_lower)
-                names.append(name)
-        return names
-
     def __eq__(self, other):
         if isinstance(other, Headers):
             return self.fields == other.fields
@@ -135,6 +150,7 @@ class Headers(object, UserDict.DictMixin):
     def __ne__(self, other):
         return not self.__eq__(other)
 
+    @always_byte_args("ascii")
     def get_all(self, name):
         """
         Like :py:meth:`get`, but does not fold multiple headers into a single one.
@@ -142,8 +158,8 @@ class Headers(object, UserDict.DictMixin):
 
         See also: https://tools.ietf.org/html/rfc7230#section-3.2.2
         """
-        name = name.lower()
-        values = [value for n, value in self.fields if n.lower() == name]
+        name_lower = name.lower()
+        values = [value for n, value in self.fields if n.lower() == name_lower]
         return values
 
     def set_all(self, name, values):
@@ -151,6 +167,8 @@ class Headers(object, UserDict.DictMixin):
         Explicitly set multiple headers for the given key.
         See: :py:meth:`get_all`
         """
+        name = always_bytes(name, "ascii")
+        values = (always_bytes(value, "ascii") for value in values)
         if name in self:
             del self[name]
         self.fields.extend(
@@ -172,28 +190,6 @@ class Headers(object, UserDict.DictMixin):
         return cls([list(field) for field in state])
 
 
-class ProtocolMixin(object):
-    def read_request(self, *args, **kwargs):  # pragma: no cover
-        raise NotImplementedError
-
-    def read_response(self, *args, **kwargs):  # pragma: no cover
-        raise NotImplementedError
-
-    def assemble(self, message):
-        if isinstance(message, Request):
-            return self.assemble_request(message)
-        elif isinstance(message, Response):
-            return self.assemble_response(message)
-        else:
-            raise ValueError("HTTP message not supported.")
-
-    def assemble_request(self, *args, **kwargs):  # pragma: no cover
-        raise NotImplementedError
-
-    def assemble_response(self, *args, **kwargs):  # pragma: no cover
-        raise NotImplementedError
-
-
 class Request(object):
     # This list is adopted legacy code.
     # We probably don't need to strip off keep-alive.
@@ -248,42 +244,14 @@ class Request(object):
             return False
 
     def __repr__(self):
-        # return "Request(%s - %s, %s)" % (self.method, self.host, self.path)
-
-        return "<HTTPRequest: {0}>".format(
-            self.legacy_first_line()[:-9]
-        )
-
-    def legacy_first_line(self, form=None):
-        if form is None:
-            form = self.form_out
-        if form == "relative":
-            return '%s %s HTTP/%s.%s' % (
-                self.method,
-                self.path,
-                self.httpversion[0],
-                self.httpversion[1],
-            )
-        elif form == "authority":
-            return '%s %s:%s HTTP/%s.%s' % (
-                self.method,
-                self.host,
-                self.port,
-                self.httpversion[0],
-                self.httpversion[1],
-            )
-        elif form == "absolute":
-            return '%s %s://%s:%s%s HTTP/%s.%s' % (
-                self.method,
-                self.scheme,
-                self.host,
-                self.port,
-                self.path,
-                self.httpversion[0],
-                self.httpversion[1],
-            )
+        if self.host and self.port:
+            hostport = "{}:{}".format(self.host, self.port)
         else:
-            raise exceptions.HttpError(400, "Invalid request form")
+            hostport = ""
+        path = self.path or ""
+        return "HTTPRequest({} {}{})".format(
+            self.method, hostport, path
+        )
 
     def anticache(self):
         """
@@ -336,7 +304,7 @@ class Request(object):
                 return self.get_form_urlencoded()
             elif HDR_FORM_MULTIPART in self.headers.get("content-type","").lower():
                 return self.get_form_multipart()
-        return odict.ODict([])
+        return ODict([])
 
     def get_form_urlencoded(self):
         """
@@ -345,16 +313,16 @@ class Request(object):
             indicates non-form data.
         """
         if self.body and HDR_FORM_URLENCODED in self.headers.get("content-type","").lower():
-            return odict.ODict(utils.urldecode(self.body))
-        return odict.ODict([])
+            return ODict(utils.urldecode(self.body))
+        return ODict([])
 
     def get_form_multipart(self):
         if self.body and HDR_FORM_MULTIPART in self.headers.get("content-type","").lower():
-            return odict.ODict(
+            return ODict(
                 utils.multipartdecode(
                     self.headers,
                     self.body))
-        return odict.ODict([])
+        return ODict([])
 
     def set_form_urlencoded(self, odict):
         """
@@ -373,8 +341,8 @@ class Request(object):
 
             Components are unquoted.
         """
-        _, _, path, _, _, _ = urlparse.urlparse(self.url)
-        return [urllib.unquote(i) for i in path.split("/") if i]
+        _, _, path, _, _, _ = urllib.parse.urlparse(self.url)
+        return [urllib.parse.unquote(i) for i in path.split(b"/") if i]
 
     def set_path_components(self, lst):
         """
@@ -382,10 +350,10 @@ class Request(object):
 
             Components are quoted.
         """
-        lst = [urllib.quote(i, safe="") for i in lst]
-        path = "/" + "/".join(lst)
-        scheme, netloc, _, params, query, fragment = urlparse.urlparse(self.url)
-        self.url = urlparse.urlunparse(
+        lst = [urllib.parse.quote(i, safe="") for i in lst]
+        path = b"/" + b"/".join(lst)
+        scheme, netloc, _, params, query, fragment = urllib.parse.urlparse(self.url)
+        self.url = urllib.parse.urlunparse(
             [scheme, netloc, path, params, query, fragment]
         )
 
@@ -393,18 +361,18 @@ class Request(object):
         """
             Gets the request query string. Returns an ODict object.
         """
-        _, _, _, _, query, _ = urlparse.urlparse(self.url)
+        _, _, _, _, query, _ = urllib.parse.urlparse(self.url)
         if query:
-            return odict.ODict(utils.urldecode(query))
-        return odict.ODict([])
+            return ODict(utils.urldecode(query))
+        return ODict([])
 
     def set_query(self, odict):
         """
             Takes an ODict object, and sets the request query string.
         """
-        scheme, netloc, path, params, _, fragment = urlparse.urlparse(self.url)
+        scheme, netloc, path, params, _, fragment = urllib.parse.urlparse(self.url)
         query = utils.urlencode(odict.lst)
-        self.url = urlparse.urlunparse(
+        self.url = urllib.parse.urlunparse(
             [scheme, netloc, path, params, query, fragment]
         )
 
@@ -421,18 +389,13 @@ class Request(object):
             but not the resolved name. This is disabled by default, as an
             attacker may spoof the host header to confuse an analyst.
         """
-        host = None
-        if hostheader:
-            host = self.headers.get("Host")
-        if not host:
-            host = self.host
-        if host:
+        if hostheader and b"Host" in self.headers:
             try:
-                return host.encode("idna")
+                return self.headers[b"Host"].decode("idna")
             except ValueError:
-                return host
-        else:
-            return None
+                pass
+        if self.host:
+            return self.host.decode("idna")
 
     def pretty_url(self, hostheader):
         if self.form_out == "authority":  # upstream proxy mode
@@ -446,7 +409,7 @@ class Request(object):
         """
             Returns a possibly empty netlib.odict.ODict object.
         """
-        ret = odict.ODict()
+        ret = ODict()
         for i in self.headers.get_all("cookie"):
             ret.extend(cookies.parse_cookie_header(i))
         return ret
@@ -477,8 +440,10 @@ class Request(object):
             Parses a URL specification, and updates the Request's information
             accordingly.
 
-            Returns False if the URL was invalid, True if the request succeeded.
+            Raises:
+                ValueError if the URL was invalid
         """
+        # TODO: Should handle incoming unicode here.
         parts = utils.parse_url(url)
         if not parts:
             raise ValueError("Invalid URL: %s" % url)
@@ -495,32 +460,6 @@ class Request(object):
         self.body = content
 
 
-class EmptyRequest(Request):
-    def __init__(
-            self,
-            form_in="",
-            method="",
-            scheme="",
-            host="",
-            port="",
-            path="",
-            httpversion=(0, 0),
-            headers=None,
-            body=""
-    ):
-        super(EmptyRequest, self).__init__(
-            form_in=form_in,
-            method=method,
-            scheme=scheme,
-            host=host,
-            port=port,
-            path=path,
-            httpversion=httpversion,
-            headers=headers,
-            body=body,
-        )
-
-
 class Response(object):
     _headers_to_strip_off = [
         'Proxy-Connection',
@@ -591,7 +530,7 @@ class Response(object):
             if v:
                 name, value, attrs = v
                 ret.append([name, [value, attrs]])
-        return odict.ODict(ret)
+        return ODict(ret)
 
     def set_cookies(self, odict):
         """
diff --git a/netlib/tcp.py b/netlib/tcp.py
index 4a7f6153..1eb417b4 100644
--- a/netlib/tcp.py
+++ b/netlib/tcp.py
@@ -834,14 +834,14 @@ class TCPServer(object):
         # If a thread has persisted after interpreter exit, the module might be
         # none.
         if traceback:
-            exc = traceback.format_exc()
-            print('-' * 40, file=fp)
+            exc = six.text_type(traceback.format_exc())
+            print(u'-' * 40, file=fp)
             print(
-                "Error in processing of request from %s:%s" % (
+                u"Error in processing of request from %s:%s" % (
                     client_address.host, client_address.port
                 ), file=fp)
             print(exc, file=fp)
-            print('-' * 40, file=fp)
+            print(u'-' * 40, file=fp)
 
     def handle_client_connection(self, conn, client_address):  # pragma: no cover
         """
diff --git a/netlib/tutils.py b/netlib/tutils.py
index 951ef3d9..65c4a313 100644
--- a/netlib/tutils.py
+++ b/netlib/tutils.py
@@ -1,9 +1,11 @@
-import cStringIO
+from io import BytesIO
 import tempfile
 import os
 import time
 import shutil
 from contextlib import contextmanager
+import six
+import sys
 
 from netlib import tcp, utils, http
 
@@ -12,7 +14,7 @@ def treader(bytes):
     """
         Construct a tcp.Read object from bytes.
     """
-    fp = cStringIO.StringIO(bytes)
+    fp = BytesIO(bytes)
     return tcp.Reader(fp)
 
 
@@ -28,7 +30,24 @@ def tmpdir(*args, **kwargs):
     shutil.rmtree(temp_workdir)
 
 
-def raises(exc, obj, *args, **kwargs):
+def _check_exception(expected, actual, exc_tb):
+    if isinstance(expected, six.string_types):
+        if expected.lower() not in str(actual).lower():
+            six.reraise(AssertionError, AssertionError(
+                "Expected %s, but caught %s" % (
+                    repr(str(expected)), actual
+                )
+            ), exc_tb)
+    else:
+        if not isinstance(actual, expected):
+            six.reraise(AssertionError, AssertionError(
+                "Expected %s, but caught %s %s" % (
+                    expected.__name__, actual.__class__.__name__, str(actual)
+                )
+            ), exc_tb)
+
+
+def raises(expected_exception, obj=None, *args, **kwargs):
     """
         Assert that a callable raises a specified exception.
 
@@ -43,28 +62,31 @@ def raises(exc, obj, *args, **kwargs):
 
         :kwargs Arguments to be passed to the callable.
     """
-    try:
-        ret = obj(*args, **kwargs)
-    except Exception as v:
-        if isinstance(exc, basestring):
-            if exc.lower() in str(v).lower():
-                return
-            else:
-                raise AssertionError(
-                    "Expected %s, but caught %s" % (
-                        repr(str(exc)), v
-                    )
-                )
+    if obj is None:
+        return RaisesContext(expected_exception)
+    else:
+        try:
+            ret = obj(*args, **kwargs)
+        except Exception as actual:
+            _check_exception(expected_exception, actual, sys.exc_info()[2])
         else:
-            if isinstance(v, exc):
-                return
-            else:
-                raise AssertionError(
-                    "Expected %s, but caught %s %s" % (
-                        exc.__name__, v.__class__.__name__, str(v)
-                    )
-                )
-    raise AssertionError("No exception raised. Return value: {}".format(ret))
+            raise AssertionError("No exception raised. Return value: {}".format(ret))
+
+
+class RaisesContext(object):
+    def __init__(self, expected_exception):
+        self.expected_exception = expected_exception
+
+    def __enter__(self):
+        return
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if not exc_type:
+            raise AssertionError("No exception raised.")
+        else:
+            _check_exception(self.expected_exception, exc_val, exc_tb)
+        return True
+
 
 test_data = utils.Data(__name__)
 
diff --git a/netlib/utils.py b/netlib/utils.py
index d6774419..fb579cac 100644
--- a/netlib/utils.py
+++ b/netlib/utils.py
@@ -1,17 +1,17 @@
-from __future__ import (absolute_import, print_function, division)
+from __future__ import absolute_import, print_function, division
 import os.path
-import cgi
-import urllib
-import urlparse
-import string
 import re
-import six
+import string
 import unicodedata
 
+import six
+
+from six.moves import urllib
+
 
-def isascii(s):
+def isascii(bytes):
     try:
-        s.decode("ascii")
+        bytes.decode("ascii")
     except ValueError:
         return False
     return True
@@ -44,8 +44,8 @@ def clean_bin(s, keep_spacing=True):
         else:
             keep = b""
         return b"".join(
-            ch if (31 < ord(ch) < 127 or ch in keep) else b"."
-            for ch in s
+            six.int2byte(ch) if (31 < ch < 127 or ch in keep) else b"."
+            for ch in six.iterbytes(s)
         )
 
 
@@ -149,10 +149,7 @@ class Data(object):
         return fullpath
 
 
-def is_valid_port(port):
-    if not 0 <= port <= 65535:
-        return False
-    return True
+_label_valid = re.compile(b"(?!-)[A-Z\d-]{1,63}(?<!-)$", re.IGNORECASE)
 
 
 def is_valid_host(host):
@@ -160,53 +157,79 @@ def is_valid_host(host):
         host.decode("idna")
     except ValueError:
         return False
-    if "\0" in host:
-        return None
-    return True
+    if len(host) > 255:
+        return False
+    if host[-1] == ".":
+        host = host[:-1]
+    return all(_label_valid.match(x) for x in host.split(b"."))
+
+
+def is_valid_port(port):
+    return 0 <= port <= 65535
+
+
+# PY2 workaround
+def decode_parse_result(result, enc):
+    if hasattr(result, "decode"):
+        return result.decode(enc)
+    else:
+        return urllib.parse.ParseResult(*[x.decode(enc) for x in result])
+
+
+# PY2 workaround
+def encode_parse_result(result, enc):
+    if hasattr(result, "encode"):
+        return result.encode(enc)
+    else:
+        return urllib.parse.ParseResult(*[x.encode(enc) for x in result])
 
 
 def parse_url(url):
     """
-        Returns a (scheme, host, port, path) tuple, or None on error.
+        URL-parsing function that checks that
+            - port is an integer 0-65535
+            - host is a valid IDNA-encoded hostname with no null-bytes
+            - path is valid ASCII
 
-        Checks that:
-            port is an integer 0-65535
-            host is a valid IDNA-encoded hostname with no null-bytes
-            path is valid ASCII
+        Args:
+            A URL (as bytes or as unicode)
+
+        Returns:
+            A (scheme, host, port, path) tuple
+
+        Raises:
+            ValueError, if the URL is not properly formatted.
     """
-    try:
-        scheme, netloc, path, params, query, fragment = urlparse.urlparse(url)
-    except ValueError:
-        return None
-    if not scheme:
-        return None
-    if '@' in netloc:
-        # FIXME: Consider what to do with the discarded credentials here Most
-        # probably we should extend the signature to return these as a separate
-        # value.
-        _, netloc = string.rsplit(netloc, '@', maxsplit=1)
-    if ':' in netloc:
-        host, port = string.rsplit(netloc, ':', maxsplit=1)
-        try:
-            port = int(port)
-        except ValueError:
-            return None
+    parsed = urllib.parse.urlparse(url)
+
+    if not parsed.hostname:
+        raise ValueError("No hostname given")
+
+    if isinstance(url, six.binary_type):
+        host = parsed.hostname
+
+        # this should not raise a ValueError
+        decode_parse_result(parsed, "ascii")
     else:
-        host = netloc
-        if scheme.endswith("https"):
-            port = 443
-        else:
-            port = 80
-    path = urlparse.urlunparse(('', '', path, params, query, fragment))
-    if not path.startswith("/"):
-        path = "/" + path
+        host = parsed.hostname.encode("idna")
+        parsed = encode_parse_result(parsed, "ascii")
+
+    port = parsed.port
+    if not port:
+        port = 443 if parsed.scheme == b"https" else 80
+
+    full_path = urllib.parse.urlunparse(
+        (b"", b"", parsed.path, parsed.params, parsed.query, parsed.fragment)
+    )
+    if not full_path.startswith(b"/"):
+        full_path = b"/" + full_path
+
     if not is_valid_host(host):
-        return None
-    if not isascii(path):
-        return None
+        raise ValueError("Invalid Host")
     if not is_valid_port(port):
-        return None
-    return scheme, host, port, path
+        raise ValueError("Invalid Port")
+
+    return parsed.scheme, host, port, full_path
 
 
 def get_header_tokens(headers, key):
@@ -217,7 +240,7 @@ def get_header_tokens(headers, key):
     """
     if key not in headers:
         return []
-    tokens = headers[key].split(",")
+    tokens = headers[key].split(b",")
     return [token.strip() for token in tokens]
 
 
@@ -228,7 +251,7 @@ def hostport(scheme, host, port):
     if (port, scheme) in [(80, "http"), (443, "https")]:
         return host
     else:
-        return "%s:%s" % (host, port)
+        return b"%s:%s" % (host, port)
 
 
 def unparse_url(scheme, host, port, path=""):
@@ -243,14 +266,14 @@ def urlencode(s):
         Takes a list of (key, value) tuples and returns a urlencoded string.
     """
     s = [tuple(i) for i in s]
-    return urllib.urlencode(s, False)
+    return urllib.parse.urlencode(s, False)
 
 
 def urldecode(s):
     """
         Takes a urlencoded string and returns a list of (key, value) tuples.
     """
-    return cgi.parse_qsl(s, keep_blank_values=True)
+    return urllib.parse.parse_qsl(s, keep_blank_values=True)
 
 
 def parse_content_type(c):
@@ -267,14 +290,14 @@ def parse_content_type(c):
 
             ("text", "html", {"charset": "UTF-8"})
     """
-    parts = c.split(";", 1)
-    ts = parts[0].split("/", 1)
+    parts = c.split(b";", 1)
+    ts = parts[0].split(b"/", 1)
     if len(ts) != 2:
         return None
     d = {}
     if len(parts) == 2:
-        for i in parts[1].split(";"):
-            clause = i.split("=", 1)
+        for i in parts[1].split(b";"):
+            clause = i.split(b"=", 1)
             if len(clause) == 2:
                 d[clause[0].strip()] = clause[1].strip()
     return ts[0].lower(), ts[1].lower(), d
@@ -289,7 +312,7 @@ def multipartdecode(headers, content):
         v = parse_content_type(v)
         if not v:
             return []
-        boundary = v[2].get("boundary")
+        boundary = v[2].get(b"boundary")
         if not boundary:
             return []
 
@@ -306,3 +329,20 @@ def multipartdecode(headers, content):
                     r.append((key, value))
         return r
     return []
+
+
+def always_bytes(unicode_or_bytes, encoding):
+    if isinstance(unicode_or_bytes, six.text_type):
+        return unicode_or_bytes.encode(encoding)
+    return unicode_or_bytes
+
+
+def always_byte_args(encoding):
+    """Decorator that transparently encodes all arguments passed as unicode"""
+    def decorator(fun):
+        def _fun(*args, **kwargs):
+            args = [always_bytes(arg, encoding) for arg in args]
+            kwargs = {k: always_bytes(v, encoding) for k, v in six.iteritems(kwargs)}
+            return fun(*args, **kwargs)
+        return _fun
+    return decorator
diff --git a/netlib/version_check.py b/netlib/version_check.py
index 1d7e025c..9cf27eea 100644
--- a/netlib/version_check.py
+++ b/netlib/version_check.py
@@ -7,6 +7,7 @@ from __future__ import division, absolute_import, print_function
 import sys
 import inspect
 import os.path
+import six
 
 import OpenSSL
 from . import version
@@ -19,8 +20,8 @@ def check_mitmproxy_version(mitmproxy_version, fp=sys.stderr):
     # consider major and minor version.
     if version.IVERSION[:2] != mitmproxy_version[:2]:
         print(
-            "You are using mitmproxy %s with netlib %s. "
-            "Most likely, that won't work - please upgrade!" % (
+            u"You are using mitmproxy %s with netlib %s. "
+            u"Most likely, that won't work - please upgrade!" % (
                 mitmproxy_version, version.VERSION
             ),
             file=fp
@@ -29,13 +30,13 @@ def check_mitmproxy_version(mitmproxy_version, fp=sys.stderr):
 
 
 def check_pyopenssl_version(min_version=PYOPENSSL_MIN_VERSION, fp=sys.stderr):
-    min_version_str = ".".join(str(x) for x in min_version)
+    min_version_str = u".".join(six.text_type(x) for x in min_version)
     try:
         v = tuple(int(x) for x in OpenSSL.__version__.split(".")[:2])
     except ValueError:
         print(
-            "Cannot parse pyOpenSSL version: {}"
-            "mitmproxy requires pyOpenSSL {} or greater.".format(
+            u"Cannot parse pyOpenSSL version: {}"
+            u"mitmproxy requires pyOpenSSL {} or greater.".format(
                 OpenSSL.__version__, min_version_str
             ),
             file=fp
@@ -43,15 +44,15 @@ def check_pyopenssl_version(min_version=PYOPENSSL_MIN_VERSION, fp=sys.stderr):
         return
     if v < min_version:
         print(
-            "You are using an outdated version of pyOpenSSL: "
-            "mitmproxy requires pyOpenSSL {} or greater.".format(min_version_str),
+            u"You are using an outdated version of pyOpenSSL: "
+            u"mitmproxy requires pyOpenSSL {} or greater.".format(min_version_str),
             file=fp
         )
         # Some users apparently have multiple versions of pyOpenSSL installed.
         # Report which one we got.
         pyopenssl_path = os.path.dirname(inspect.getfile(OpenSSL))
         print(
-            "Your pyOpenSSL {} installation is located at {}".format(
+            u"Your pyOpenSSL {} installation is located at {}".format(
                 OpenSSL.__version__, pyopenssl_path
             ),
             file=fp
diff --git a/netlib/websockets/__init__.py b/netlib/websockets/__init__.py
index 5acf7696..1c143919 100644
--- a/netlib/websockets/__init__.py
+++ b/netlib/websockets/__init__.py
@@ -1,2 +1,2 @@
-from frame import *
-from protocol import *
+from .frame import *
+from .protocol import *