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

src/ssh_audit/readbuf.py

@@ -0,0 +1,92 @@
+"""
+   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 ReadBuf:
+    def __init__(self, data: Optional[bytes] = None) -> None:
+        super(ReadBuf, self).__init__()
+        self._buf = io.BytesIO(data) if data is not None else io.BytesIO()
+        self._len = len(data) if data is not None else 0
+
+    @property
+    def unread_len(self) -> int:
+        return self._len - self._buf.tell()
+
+    def read(self, size: int) -> bytes:
+        return self._buf.read(size)
+
+    def read_byte(self) -> int:
+        v = struct.unpack('B', self.read(1))[0]  # type: int
+        return v
+
+    def read_bool(self) -> bool:
+        return self.read_byte() != 0
+
+    def read_int(self) -> int:
+        v = struct.unpack('>I', self.read(4))[0]  # type: int
+        return v
+
+    def read_list(self) -> List[str]:
+        list_size = self.read_int()
+        return self.read(list_size).decode('utf-8', 'replace').split(',')
+
+    def read_string(self) -> bytes:
+        n = self.read_int()
+        return self.read(n)
+
+    @classmethod
+    def _parse_mpint(cls, v: bytes, pad: bytes, f: str) -> int:
+        r = 0
+        if len(v) % 4 != 0:
+            v = pad * (4 - (len(v) % 4)) + v
+        for i in range(0, len(v), 4):
+            r = (r << 32) | struct.unpack(f, v[i:i + 4])[0]
+        return r
+
+    def read_mpint1(self) -> int:
+        # NOTE: Data Type Enc @ http://www.snailbook.com/docs/protocol-1.5.txt
+        bits = struct.unpack('>H', self.read(2))[0]
+        n = (bits + 7) // 8
+        return self._parse_mpint(self.read(n), b'\x00', '>I')
+
+    def read_mpint2(self) -> int:
+        # NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt
+        v = self.read_string()
+        if len(v) == 0:
+            return 0
+        pad, f = (b'\xff', '>i') if ord(v[0:1]) & 0x80 != 0 else (b'\x00', '>I')
+        return self._parse_mpint(v, pad, f)
+
+    def read_line(self) -> str:
+        return self._buf.readline().rstrip().decode('utf-8', 'replace')
+
+    def reset(self) -> None:
+        self._buf = io.BytesIO()
+        self._len = 0