1 files changed, 418 insertions, 0 deletions
diff --git a/netlib/utils.py b/netlib/utils.py
new file mode 100644
index 00000000..f7bb5c4b
--- /dev/null
+++ b/netlib/utils.py
@@ -0,0 +1,418 @@
+from __future__ import absolute_import, print_function, division
+import os.path
+import re
+import codecs
+import unicodedata
+from abc import ABCMeta, abstractmethod
+import importlib
+import inspect
+
+import six
+
+from six.moves import urllib
+import hyperframe
+
+
+@six.add_metaclass(ABCMeta)
+class Serializable(object):
+    """
+    Abstract Base Class that defines an API to save an object's state and restore it later on.
+    """
+
+    @classmethod
+    @abstractmethod
+    def from_state(cls, state):
+        """
+        Create a new object from the given state.
+        """
+        raise NotImplementedError()
+
+    @abstractmethod
+    def get_state(self):
+        """
+        Retrieve object state.
+        """
+        raise NotImplementedError()
+
+    @abstractmethod
+    def set_state(self, state):
+        """
+        Set object state to the given state.
+        """
+        raise NotImplementedError()
+
+
+def always_bytes(unicode_or_bytes, *encode_args):
+    if isinstance(unicode_or_bytes, six.text_type):
+        return unicode_or_bytes.encode(*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
+    :py:class:`str` type, using latin1 encoding if conversion is necessary.
+
+    https://www.python.org/dev/peps/pep-3333/#a-note-on-string-types
+    """
+    if not isinstance(s, (six.binary_type, six.text_type)):
+        raise TypeError("%r is neither bytes nor unicode" % s)
+    if six.PY3:
+        if isinstance(s, six.binary_type):
+            return s.decode(*encoding_opts)
+    else:
+        if isinstance(s, six.text_type):
+            return s.encode(*encoding_opts)
+    return s
+
+
+def isascii(bytes):
+    try:
+        bytes.decode("ascii")
+    except ValueError:
+        return False
+    return True
+
+
+def clean_bin(s, keep_spacing=True):
+    """
+        Cleans binary data to make it safe to display.
+
+        Args:
+            keep_spacing: If False, tabs and newlines will also be replaced.
+    """
+    if isinstance(s, six.text_type):
+        if keep_spacing:
+            keep = u" \n\r\t"
+        else:
+            keep = u" "
+        return u"".join(
+            ch if (unicodedata.category(ch)[0] not in "CZ" or ch in keep) else u"."
+            for ch in s
+        )
+    else:
+        if keep_spacing:
+            keep = (9, 10, 13)  # \t, \n, \r,
+        else:
+            keep = ()
+        return b"".join(
+            six.int2byte(ch) if (31 < ch < 127 or ch in keep) else b"."
+            for ch in six.iterbytes(s)
+        )
+
+
+def hexdump(s):
+    """
+        Returns:
+            A generator of (offset, hex, str) tuples
+    """
+    for i in range(0, len(s), 16):
+        offset = "{:0=10x}".format(i).encode()
+        part = s[i:i + 16]
+        x = b" ".join("{:0=2x}".format(i).encode() for i in six.iterbytes(part))
+        x = x.ljust(47)  # 16*2 + 15
+        yield (offset, x, clean_bin(part, False))
+
+
+def setbit(byte, offset, value):
+    """
+        Set a bit in a byte to 1 if value is truthy, 0 if not.
+    """
+    if value:
+        return byte | (1 << offset)
+    else:
+        return byte & ~(1 << offset)
+
+
+def getbit(byte, offset):
+    mask = 1 << offset
+    return bool(byte & mask)
+
+
+class BiDi(object):
+
+    """
+        A wee utility class for keeping bi-directional mappings, like field
+        constants in protocols. Names are attributes on the object, dict-like
+        access maps values to names:
+
+        CONST = BiDi(a=1, b=2)
+        assert CONST.a == 1
+        assert CONST.get_name(1) == "a"
+    """
+
+    def __init__(self, **kwargs):
+        self.names = kwargs
+        self.values = {}
+        for k, v in kwargs.items():
+            self.values[v] = k
+        if len(self.names) != len(self.values):
+            raise ValueError("Duplicate values not allowed.")
+
+    def __getattr__(self, k):
+        if k in self.names:
+            return self.names[k]
+        raise AttributeError("No such attribute: %s", k)
+
+    def get_name(self, n, default=None):
+        return self.values.get(n, default)
+
+
+def pretty_size(size):
+    suffixes = [
+        ("B", 2 ** 10),
+        ("kB", 2 ** 20),
+        ("MB", 2 ** 30),
+    ]
+    for suf, lim in suffixes:
+        if size >= lim:
+            continue
+        else:
+            x = round(size / float(lim / 2 ** 10), 2)
+            if x == int(x):
+                x = int(x)
+            return str(x) + suf
+
+
+class Data(object):
+
+    def __init__(self, name):
+        m = importlib.import_module(name)
+        dirname = os.path.dirname(inspect.getsourcefile(m))
+        self.dirname = os.path.abspath(dirname)
+
+    def path(self, path):
+        """
+            Returns a path to the package data housed at 'path' under this
+            module.Path can be a path to a file, or to a directory.
+
+            This function will raise ValueError if the path does not exist.
+        """
+        fullpath = os.path.join(self.dirname, path)
+        if not os.path.exists(fullpath):
+            raise ValueError("dataPath: %s does not exist." % fullpath)
+        return fullpath
+
+
+_label_valid = re.compile(b"(?!-)[A-Z\d-]{1,63}(?<!-)$", re.IGNORECASE)
+
+
+def is_valid_host(host):
+    """
+    Checks if a hostname is valid.
+
+    Args:
+      host (bytes): The hostname
+    """
+    try:
+        host.decode("idna")
+    except ValueError:
+        return False
+    if len(host) > 255:
+        return False
+    if host[-1] == b".":
+        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):
+    """
+        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
+
+        Args:
+            A URL (as bytes or as unicode)
+
+        Returns:
+            A (scheme, host, port, path) tuple
+
+        Raises:
+            ValueError, if the URL is not properly formatted.
+    """
+    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,
+        # but we try to be very forgiving here and accept just everything.
+        # decode_parse_result(parsed, "ascii")
+    else:
+        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):
+        raise ValueError("Invalid Host")
+    if not is_valid_port(port):
+        raise ValueError("Invalid Port")
+
+    return parsed.scheme, host, port, full_path
+
+
+def get_header_tokens(headers, key):
+    """
+        Retrieve all tokens for a header key. A number of different headers
+        follow a pattern where each header line can containe comma-separated
+        tokens, and headers can be set multiple times.
+    """
+    if key not in headers:
+        return []
+    tokens = headers[key].split(",")
+    return [token.strip() for token in tokens]
+
+
+def hostport(scheme, host, port):
+    """
+        Returns the host component, with a port specifcation if needed.
+    """
+    if (port, scheme) in [(80, "http"), (443, "https"), (80, b"http"), (443, b"https")]:
+        return host
+    else:
+        if isinstance(host, six.binary_type):
+            return b"%s:%d" % (host, port)
+        else:
+            return "%s:%d" % (host, port)
+
+
+def unparse_url(scheme, host, port, path=""):
+    """
+    Returns a URL string, constructed from the specified components.
+
+    Args:
+        All args must be str.
+    """
+    return "%s://%s%s" % (scheme, hostport(scheme, host, port), path)
+
+
+def urlencode(s):
+    """
+        Takes a list of (key, value) tuples and returns a urlencoded string.
+    """
+    s = [tuple(i) for i in s]
+    return urllib.parse.urlencode(s, False)
+
+
+def urldecode(s):
+    """
+        Takes a urlencoded string and returns a list of (key, value) tuples.
+    """
+    return urllib.parse.parse_qsl(s, keep_blank_values=True)
+
+
+def parse_content_type(c):
+    """
+        A simple parser for content-type values. Returns a (type, subtype,
+        parameters) tuple, where type and subtype are strings, and parameters
+        is a dict. If the string could not be parsed, return None.
+
+        E.g. the following string:
+
+            text/html; charset=UTF-8
+
+        Returns:
+
+            ("text", "html", {"charset": "UTF-8"})
+    """
+    parts = c.split(";", 1)
+    ts = parts[0].split("/", 1)
+    if len(ts) != 2:
+        return None
+    d = {}
+    if len(parts) == 2:
+        for i in parts[1].split(";"):
+            clause = i.split("=", 1)
+            if len(clause) == 2:
+                d[clause[0].strip()] = clause[1].strip()
+    return ts[0].lower(), ts[1].lower(), d
+
+
+def multipartdecode(headers, content):
+    """
+        Takes a multipart boundary encoded string and returns list of (key, value) tuples.
+    """
+    v = headers.get("content-type")
+    if v:
+        v = parse_content_type(v)
+        if not v:
+            return []
+        try:
+            boundary = v[2]["boundary"].encode("ascii")
+        except (KeyError, UnicodeError):
+            return []
+
+        rx = re.compile(br'\bname="([^"]+)"')
+        r = []
+
+        for i in content.split(b"--" + boundary):
+            parts = i.splitlines()
+            if len(parts) > 1 and parts[0][0:2] != b"--":
+                match = rx.search(parts[1])
+                if match:
+                    key = match.group(1)
+                    value = b"".join(parts[3 + parts[2:].index(b""):])
+                    r.append((key, value))
+        return r
+    return []
+
+
+def http2_read_raw_frame(rfile):
+    header = rfile.safe_read(9)
+    length = int(codecs.encode(header[:3], 'hex_codec'), 16)
+
+    if length == 4740180:
+        raise ValueError("Length field looks more like HTTP/1.1: %s" % rfile.peek(20))
+
+    body = rfile.safe_read(length)
+    return [header, body]
+
+def http2_read_frame(rfile):
+    header, body = http2_read_raw_frame(rfile)
+    frame, length = hyperframe.frame.Frame.parse_frame_header(header)
+    frame.parse_body(memoryview(body))
+    return frame