1 files changed, 92 insertions, 0 deletions
diff --git a/src/ssh_audit/banner.py b/src/ssh_audit/banner.py
new file mode 100644
index 0000000..da6ee17
--- /dev/null
+++ b/src/ssh_audit/banner.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 re
+
+# pylint: disable=unused-import
+from typing import Dict, List, Set, Sequence, Tuple, Iterable  # noqa: F401
+from typing import Callable, Optional, Union, Any  # noqa: F401
+
+from ssh_audit.utils import Utils
+
+
+class Banner:
+    _RXP, _RXR = r'SSH-\d\.\s*?\d+', r'(-\s*([^\s]*)(?:\s+(.*))?)?'
+    RX_PROTOCOL = re.compile(re.sub(r'\\d(\+?)', r'(\\d\g<1>)', _RXP))
+    RX_BANNER = re.compile(r'^({0}(?:(?:-{0})*)){1}$'.format(_RXP, _RXR))
+
+    def __init__(self, protocol: Tuple[int, int], software: Optional[str], comments: Optional[str], valid_ascii: bool) -> None:
+        self.__protocol = protocol
+        self.__software = software
+        self.__comments = comments
+        self.__valid_ascii = valid_ascii
+
+    @property
+    def protocol(self) -> Tuple[int, int]:
+        return self.__protocol
+
+    @property
+    def software(self) -> Optional[str]:
+        return self.__software
+
+    @property
+    def comments(self) -> Optional[str]:
+        return self.__comments
+
+    @property
+    def valid_ascii(self) -> bool:
+        return self.__valid_ascii
+
+    def __str__(self) -> str:
+        r = 'SSH-{}.{}'.format(self.protocol[0], self.protocol[1])
+        if self.software is not None:
+            r += '-{}'.format(self.software)
+        if bool(self.comments):
+            r += ' {}'.format(self.comments)
+        return r
+
+    def __repr__(self) -> str:
+        p = '{}.{}'.format(self.protocol[0], self.protocol[1])
+        r = 'protocol={}'.format(p)
+        if self.software is not None:
+            r += ', software={}'.format(self.software)
+        if bool(self.comments):
+            r += ', comments={}'.format(self.comments)
+        return '<{}({})>'.format(self.__class__.__name__, r)
+
+    @classmethod
+    def parse(cls, banner: str) -> Optional['Banner']:
+        valid_ascii = Utils.is_print_ascii(banner)
+        ascii_banner = Utils.to_print_ascii(banner)
+        mx = cls.RX_BANNER.match(ascii_banner)
+        if mx is None:
+            return None
+        protocol = min(re.findall(cls.RX_PROTOCOL, mx.group(1)))
+        protocol = (int(protocol[0]), int(protocol[1]))
+        software = (mx.group(3) or '').strip() or None
+        if software is None and (mx.group(2) or '').startswith('-'):
+            software = ''
+        comments = (mx.group(4) or '').strip() or None
+        if comments is not None:
+            comments = re.sub(r'\s+', ' ', comments)
+        return cls(protocol, software, comments, valid_ascii)