94 lines
2.0 KiB
Python
94 lines
2.0 KiB
Python
# -*- test-case-name: twisted.conch.test.test_ssh -*-
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# Copyright (c) Twisted Matrix Laboratories.
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# See LICENSE for details.
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"""
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Common functions for the SSH classes.
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Maintainer: Paul Swartz
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"""
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from __future__ import absolute_import, division
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import struct
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from cryptography.utils import int_from_bytes, int_to_bytes
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from twisted.python.compat import unicode
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from twisted.python.deprecate import deprecated
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from twisted.python.versions import Version
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__all__ = ["NS", "getNS", "MP", "getMP", "ffs"]
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def NS(t):
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"""
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net string
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"""
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if isinstance(t, unicode):
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t = t.encode("utf-8")
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return struct.pack('!L', len(t)) + t
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def getNS(s, count=1):
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"""
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get net string
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"""
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ns = []
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c = 0
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for i in range(count):
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l, = struct.unpack('!L', s[c:c + 4])
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ns.append(s[c + 4:4 + l + c])
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c += 4 + l
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return tuple(ns) + (s[c:],)
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def MP(number):
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if number == 0:
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return b'\000' * 4
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assert number > 0
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bn = int_to_bytes(number)
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if ord(bn[0:1]) & 128:
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bn = b'\000' + bn
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return struct.pack('>L', len(bn)) + bn
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def getMP(data, count=1):
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"""
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Get multiple precision integer out of the string. A multiple precision
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integer is stored as a 4-byte length followed by length bytes of the
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integer. If count is specified, get count integers out of the string.
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The return value is a tuple of count integers followed by the rest of
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the data.
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"""
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mp = []
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c = 0
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for i in range(count):
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length, = struct.unpack('>L', data[c:c + 4])
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mp.append(int_from_bytes(data[c + 4:c + 4 + length], 'big'))
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c += 4 + length
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return tuple(mp) + (data[c:],)
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def ffs(c, s):
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"""
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first from second
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goes through the first list, looking for items in the second, returns the first one
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"""
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for i in c:
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if i in s:
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return i
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@deprecated(Version("Twisted", 16, 5, 0))
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def install():
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# This used to install gmpy, but is technically public API, so just do
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# nothing.
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pass
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