implement basic HTTP/2 frame classes

1 files changed, 375 insertions, 0 deletions

diff --git a/netlib/h2/frame.py b/netlib/h2/frame.py
new file mode 100644
index 00000000..52cc2992
--- /dev/null
+++ b/netlib/h2/frame.py
@@ -0,0 +1,375 @@
+import base64
+import hashlib
+import os
+import struct
+import io
+
+from .. import utils, odict, tcp
+
+class Frame(object):
+    """
+        Baseclass Frame
+        contains header
+        payload is defined in subclasses
+    """
+
+    FLAG_NO_FLAGS = 0x0
+    FLAG_ACK = 0x1
+    FLAG_END_STREAM = 0x1
+    FLAG_END_HEADERS = 0x4
+    FLAG_PADDED = 0x8
+    FLAG_PRIORITY = 0x20
+
+    def __init__(self, length, flags, stream_id):
+        valid_flags = reduce(lambda x, y: x | y, self.VALID_FLAGS, 0x0)
+        if flags | valid_flags != valid_flags:
+            raise ValueError('invalid flags detected.')
+
+        self.length = length
+        self.flags = flags
+        self.stream_id = stream_id
+
+    @classmethod
+    def from_bytes(self, data):
+        fields = struct.unpack("!HBBBL", data[:9])
+        length = (fields[0] << 8) + fields[1]
+        # type is already deducted from class
+        flags = fields[3]
+        stream_id = fields[4]
+        return FRAMES[fields[2]].from_bytes(length, flags, stream_id, data[9:])
+
+    def to_bytes(self):
+        payload = self.payload_bytes()
+        self.length = len(payload)
+
+        b = struct.pack('!HB', self.length & 0xFFFF00, self.length & 0x0000FF)
+        b += struct.pack('!B', self.TYPE)
+        b += struct.pack('!B', self.flags)
+        b += struct.pack('!L', self.stream_id & 0x7FFFFFFF)
+        b += payload
+
+        return b
+
+    def __eq__(self, other):
+        return self.to_bytes() == other.to_bytes()
+
+class DataFrame(Frame):
+    TYPE = 0x0
+    VALID_FLAGS = [Frame.FLAG_END_STREAM, Frame.FLAG_PADDED]
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, payload=b'', pad_length=0):
+        super(DataFrame, self).__init__(length, flags, stream_id)
+        self.payload = payload
+        self.pad_length = pad_length
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        if f.flags & self.FLAG_PADDED:
+            f.pad_length = struct.unpack('!B', payload[0])[0]
+            f.payload = payload[1:-f.pad_length]
+        else:
+            f.payload = payload
+
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id == 0x0:
+            raise ValueError('DATA frames MUST be associated with a stream.')
+
+        b = b''
+        if self.flags & self.FLAG_PADDED:
+            b += struct.pack('!B', self.pad_length)
+
+        b += bytes(self.payload)
+
+        if self.flags & self.FLAG_PADDED:
+            b += b'\0' * self.pad_length
+
+        return b
+
+class HeadersFrame(Frame):
+    TYPE = 0x1
+    VALID_FLAGS = [Frame.FLAG_END_STREAM, Frame.FLAG_END_HEADERS, Frame.FLAG_PADDED, Frame.FLAG_PRIORITY]
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, header_block_fragment=b'', pad_length=0, exclusive=False, stream_dependency=0x0, weight=0):
+        super(HeadersFrame, self).__init__(length, flags, stream_id)
+        self.header_block_fragment = header_block_fragment
+        self.pad_length = pad_length
+        self.exclusive = exclusive
+        self.stream_dependency = stream_dependency
+        self.weight = weight
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        if f.flags & self.FLAG_PADDED:
+            f.pad_length = struct.unpack('!B', payload[0])[0]
+            f.header_block_fragment = payload[1:-f.pad_length]
+        else:
+            f.header_block_fragment = payload[0:]
+
+        if f.flags & self.FLAG_PRIORITY:
+            f.stream_dependency, f.weight = struct.unpack('!LB', f.header_block_fragment[:5])
+            f.exclusive = bool(f.stream_dependency >> 31)
+            f.stream_dependency &= 0x7FFFFFFF
+            f.header_block_fragment = f.header_block_fragment[5:]
+
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id == 0x0:
+            raise ValueError('HEADERS frames MUST be associated with a stream.')
+
+        b = b''
+        if self.flags & self.FLAG_PADDED:
+            b += struct.pack('!B', self.pad_length)
+
+        if self.flags & self.FLAG_PRIORITY:
+            b += struct.pack('!LB', (int(self.exclusive) << 31) | self.stream_dependency, self.weight)
+
+        b += bytes(self.header_block_fragment)
+
+        if self.flags & self.FLAG_PADDED:
+            b += b'\0' * self.pad_length
+
+        return b
+
+class PriorityFrame(Frame):
+    TYPE = 0x2
+    VALID_FLAGS = []
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, exclusive=False, stream_dependency=0x0, weight=0):
+        super(PriorityFrame, self).__init__(length, flags, stream_id)
+        self.exclusive = exclusive
+        self.stream_dependency = stream_dependency
+        self.weight = weight
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        f.stream_dependency, f.weight = struct.unpack('!LB', payload)
+        f.exclusive = bool(f.stream_dependency >> 31)
+        f.stream_dependency &= 0x7FFFFFFF
+
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id == 0x0:
+            raise ValueError('PRIORITY frames MUST be associated with a stream.')
+
+        if self.stream_dependency == 0x0:
+            raise ValueError('stream dependency is invalid.')
+
+        return struct.pack('!LB', (int(self.exclusive) << 31) | self.stream_dependency, self.weight)
+
+class RstStreamFrame(Frame):
+    TYPE = 0x3
+    VALID_FLAGS = []
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, error_code=0x0):
+        super(RstStreamFrame, self).__init__(length, flags, stream_id)
+        self.error_code = error_code
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+        f.error_code = struct.unpack('!L', payload)[0]
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id == 0x0:
+            raise ValueError('RST_STREAM frames MUST be associated with a stream.')
+
+        return struct.pack('!L', self.error_code)
+
+class SettingsFrame(Frame):
+    TYPE = 0x4
+    VALID_FLAGS = [Frame.FLAG_ACK]
+
+    SETTINGS = utils.BiDi(
+        SETTINGS_HEADER_TABLE_SIZE = 0x1,
+        SETTINGS_ENABLE_PUSH = 0x2,
+        SETTINGS_MAX_CONCURRENT_STREAMS = 0x3,
+        SETTINGS_INITIAL_WINDOW_SIZE = 0x4,
+        SETTINGS_MAX_FRAME_SIZE = 0x5,
+        SETTINGS_MAX_HEADER_LIST_SIZE = 0x6,
+        )
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, settings={}):
+        super(SettingsFrame, self).__init__(length, flags, stream_id)
+        self.settings = settings
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        for i in xrange(0, len(payload), 6):
+            identifier, value = struct.unpack("!HL", payload[i:i+6])
+            f.settings[identifier] = value
+
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id != 0x0:
+            raise ValueError('SETTINGS frames MUST NOT be associated with a stream.')
+
+        b = b''
+        for identifier, value in self.settings.items():
+            b += struct.pack("!HL", identifier & 0xFF, value)
+
+        return b
+
+class PushPromiseFrame(Frame):
+    TYPE = 0x5
+    VALID_FLAGS = [Frame.FLAG_END_HEADERS, Frame.FLAG_PADDED]
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, promised_stream=0x0, header_block_fragment=b'', pad_length=0):
+        super(PushPromiseFrame, self).__init__(length, flags, stream_id)
+        self.pad_length = pad_length
+        self.promised_stream = promised_stream
+        self.header_block_fragment = header_block_fragment
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        if f.flags & self.FLAG_PADDED:
+            f.pad_length, f.promised_stream = struct.unpack('!BL', payload[:5])
+            f.header_block_fragment = payload[5:-f.pad_length]
+        else:
+            f.promised_stream = int(struct.unpack("!L", payload[:4])[0])
+            f.header_block_fragment = payload[4:]
+
+        f.promised_stream &= 0x7FFFFFFF
+
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id == 0x0:
+            raise ValueError('PUSH_PROMISE frames MUST be associated with a stream.')
+
+        if self.promised_stream == 0x0:
+            raise ValueError('Promised stream id not valid.')
+
+        b = b''
+        if self.flags & self.FLAG_PADDED:
+            b += struct.pack('!B', self.pad_length)
+
+        b += struct.pack('!L', self.promised_stream & 0x7FFFFFFF)
+        b += bytes(self.header_block_fragment)
+
+        if self.flags & self.FLAG_PADDED:
+            b += b'\0' * self.pad_length
+
+        return b
+
+class PingFrame(Frame):
+    TYPE = 0x6
+    VALID_FLAGS = [Frame.FLAG_ACK]
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, payload=b''):
+        super(PingFrame, self).__init__(length, flags, stream_id)
+        self.payload = payload
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+        f.payload = payload
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id != 0x0:
+            raise ValueError('PING frames MUST NOT be associated with a stream.')
+
+        b = self.payload[0:8]
+        b += b'\0' * (8 - len(b))
+        return b
+
+class GoAwayFrame(Frame):
+    TYPE = 0x7
+    VALID_FLAGS = []
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, last_stream=0x0, error_code=0x0, data=b''):
+        super(GoAwayFrame, self).__init__(length, flags, stream_id)
+        self.last_stream = last_stream
+        self.error_code = error_code
+        self.data = data
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        f.last_stream, f.error_code = struct.unpack("!LL", payload[:8])
+        f.last_stream &= 0x7FFFFFFF
+        f.data = payload[8:]
+
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id != 0x0:
+            raise ValueError('GOAWAY frames MUST NOT be associated with a stream.')
+
+        b = struct.pack('!LL', self.last_stream & 0x7FFFFFFF, self.error_code)
+        b += bytes(self.data)
+        return b
+
+class WindowUpdateFrame(Frame):
+    TYPE = 0x8
+    VALID_FLAGS = []
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, window_size_increment=0x0):
+        super(WindowUpdateFrame, self).__init__(length, flags, stream_id)
+        self.window_size_increment = window_size_increment
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+
+        f.window_size_increment = struct.unpack("!L", payload)[0]
+        f.window_size_increment &= 0x7FFFFFFF
+
+        return f
+
+    def payload_bytes(self):
+        if self.window_size_increment <= 0 or self.window_size_increment >= 2**31:
+            raise ValueError('Window Szie Increment MUST be greater than 0 and less than 2^31.')
+
+        return struct.pack('!L', self.window_size_increment & 0x7FFFFFFF)
+
+class ContinuationFrame(Frame):
+    TYPE = 0x9
+    VALID_FLAGS = [Frame.FLAG_END_HEADERS]
+
+    def __init__(self, length=0, flags=Frame.FLAG_NO_FLAGS, stream_id=0x0, header_block_fragment=b''):
+        super(ContinuationFrame, self).__init__(length, flags, stream_id)
+        self.header_block_fragment = header_block_fragment
+
+    @classmethod
+    def from_bytes(self, length, flags, stream_id, payload):
+        f = self(length=length, flags=flags, stream_id=stream_id)
+        f.header_block_fragment = payload
+        return f
+
+    def payload_bytes(self):
+        if self.stream_id == 0x0:
+            raise ValueError('CONTINUATION frames MUST be associated with a stream.')
+
+        return self.header_block_fragment
+
+_FRAME_CLASSES = [
+    DataFrame,
+    HeadersFrame,
+    PriorityFrame,
+    RstStreamFrame,
+    SettingsFrame,
+    PushPromiseFrame,
+    PingFrame,
+    GoAwayFrame,
+    WindowUpdateFrame,
+    ContinuationFrame
+]
+FRAMES = {cls.TYPE: cls for cls in _FRAME_CLASSES}