Split ssh_audit.py into separate files (#47).

src/ssh_audit/writebuf.py

@@ -0,0 +1,108 @@
+"""
+   The MIT License (MIT)
+
+   Copyright (C) 2017 Andris Raugulis (moo@arthepsy.eu)
+
+   Permission is hereby granted, free of charge, to any person obtaining a copy
+   of this software and associated documentation files (the "Software"), to deal
+   in the Software without restriction, including without limitation the rights
+   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+   copies of the Software, and to permit persons to whom the Software is
+   furnished to do so, subject to the following conditions:
+
+   The above copyright notice and this permission notice shall be included in
+   all copies or substantial portions of the Software.
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+   THE SOFTWARE.
+"""
+import io
+import struct
+
+# pylint: disable=unused-import
+from typing import Dict, List, Set, Sequence, Tuple, Iterable  # noqa: F401
+from typing import Callable, Optional, Union, Any  # noqa: F401
+
+
+class WriteBuf:
+    def __init__(self, data: Optional[bytes] = None) -> None:
+        super(WriteBuf, self).__init__()
+        self._wbuf = io.BytesIO(data) if data is not None else io.BytesIO()
+
+    def write(self, data: bytes) -> 'WriteBuf':
+        self._wbuf.write(data)
+        return self
+
+    def write_byte(self, v: int) -> 'WriteBuf':
+        return self.write(struct.pack('B', v))
+
+    def write_bool(self, v: bool) -> 'WriteBuf':
+        return self.write_byte(1 if v else 0)
+
+    def write_int(self, v: int) -> 'WriteBuf':
+        return self.write(struct.pack('>I', v))
+
+    def write_string(self, v: Union[bytes, str]) -> 'WriteBuf':
+        if not isinstance(v, bytes):
+            v = bytes(bytearray(v, 'utf-8'))
+        self.write_int(len(v))
+        return self.write(v)
+
+    def write_list(self, v: List[str]) -> 'WriteBuf':
+        return self.write_string(u','.join(v))
+
+    @classmethod
+    def _bitlength(cls, n: int) -> int:
+        try:
+            return n.bit_length()
+        except AttributeError:
+            return len(bin(n)) - (2 if n > 0 else 3)
+
+    @classmethod
+    def _create_mpint(cls, n: int, signed: bool = True, bits: Optional[int] = None) -> bytes:
+        if bits is None:
+            bits = cls._bitlength(n)
+        length = bits // 8 + (1 if n != 0 else 0)
+        ql = (length + 7) // 8
+        fmt, v2 = '>{}Q'.format(ql), [0] * ql
+        for i in range(ql):
+            v2[ql - i - 1] = n & 0xffffffffffffffff
+            n >>= 64
+        data = bytes(struct.pack(fmt, *v2)[-length:])
+        if not signed:
+            data = data.lstrip(b'\x00')
+        elif data.startswith(b'\xff\x80'):
+            data = data[1:]
+        return data
+
+    def write_mpint1(self, n: int) -> 'WriteBuf':
+        # NOTE: Data Type Enc @ http://www.snailbook.com/docs/protocol-1.5.txt
+        bits = self._bitlength(n)
+        data = self._create_mpint(n, False, bits)
+        self.write(struct.pack('>H', bits))
+        return self.write(data)
+
+    def write_mpint2(self, n: int) -> 'WriteBuf':
+        # NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt
+        data = self._create_mpint(n)
+        return self.write_string(data)
+
+    def write_line(self, v: Union[bytes, str]) -> 'WriteBuf':
+        if not isinstance(v, bytes):
+            v = bytes(bytearray(v, 'utf-8'))
+        v += b'\r\n'
+        return self.write(v)
+
+    def write_flush(self) -> bytes:
+        payload = self._wbuf.getvalue()
+        self._wbuf.truncate(0)
+        self._wbuf.seek(0)
+        return payload
+
+    def reset(self) -> None:
+        self._wbuf = io.BytesIO()