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Implement mpint1 read/write. Optimize mpint writing. Test mpint1.

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This commit is contained in:
Andris Raugulis 2016-09-15 06:09:08 +03:00
parent 089d7d597c
commit 285d7280eb
2 changed files with 59 additions and 31 deletions
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46
ssh-audit.py
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@ -172,18 +172,28 @@ class ReadBuf(object):
n = self.read_int() n = self.read_int()
return self.read(n) return self.read(n)
def read_mpint2(self): def _parse_mpint(self, v, pad, sf):
# NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt r = 0
r, v = 0, self.read_string()
if len(v) == 0:
return r
pad, sf = (b'\xff', '>i') if ord(v[0:1]) & 0x80 else (b'\x00', '>I')
if len(v) % 4: if len(v) % 4:
v = pad * (4 - (len(v) % 4)) + v v = pad * (4 - (len(v) % 4)) + v
for i in range(0, len(v), 4): for i in range(0, len(v), 4):
r = (r << 32) | struct.unpack(sf, v[i:i + 4])[0] r = (r << 32) | struct.unpack(sf, v[i:i + 4])[0]
return r return r
def read_mpint1(self):
# 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):
# NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt
v = self.read_string()
if len(v) == 0:
return 0
pad, sf = (b'\xff', '>i') if ord(v[0:1]) & 0x80 else (b'\x00', '>I')
return self._parse_mpint(v, pad, sf)
def read_line(self): def read_line(self):
return self._buf.readline().rstrip().decode('utf-8') return self._buf.readline().rstrip().decode('utf-8')
@ -215,13 +225,27 @@ class WriteBuf(object):
def write_list(self, v): def write_list(self, v):
self.write_string(u','.join(v)) self.write_string(u','.join(v))
def _create_mpint(self, v):
length = v.bit_length() // 8 + (1 if v != 0 else 0)
ql = (length + 7) // 8
fmt, v2 = '>{0}Q'.format(ql), [b'\x00'] * ql
for i in range(ql):
v2[ql - i - 1] = (v & 0xffffffffffffffff)
v >>= 64
data = bytes(struct.pack(fmt, *v2)[-length:])
if data.startswith(b'\xff\x80'):
data = data[1:]
return data
def write_mpint1(self, v):
# NOTE: Data Type Enc @ http://www.snailbook.com/docs/protocol-1.5.txt
data = self._create_mpint(v)
self.write(struct.pack('>H', v.bit_length()))
return self.write(data)
def write_mpint2(self, v): def write_mpint2(self, v):
# NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt # NOTE: Section 5 @ https://www.ietf.org/rfc/rfc4251.txt
length = v.bit_length() // 8 + (1 if v != 0 else 0) data = self._create_mpint(v)
data = [(v >> i * 8) & 0xff for i in reversed(range(length))]
if length > 1 and data[0] == 0xff and data[1] & 0x80:
data.pop(0)
data = bytes(bytearray(data))
return self.write_string(data) return self.write_string(data)
def write_flush(self): def write_flush(self):

42
test/test_protocol.py
View File

@ -15,23 +15,27 @@ class TestProtocol(object):
data = [int(v[i * 2:i * 2 + 2], 16) for i in range(len(v) // 2)] data = [int(v[i * 2:i * 2 + 2], 16) for i in range(len(v) // 2)]
return bytes(bytearray(data)) return bytes(bytearray(data))
def test_mpint2_write(self): def test_mpint1(self):
wbuf, _b = self.wbuf(), self._b mpint1w = lambda x: self.wbuf().write_mpint1(x).write_flush()
mpint = lambda x: wbuf.write_mpint2(x).write_flush() mpint1r = lambda x: self.rbuf(x).read_mpint1()
assert mpint(0x0) == _b('00 00 00 00') tc = [(0x0, '00 00'),
assert mpint(0x80) == _b('00 00 00 02 00 80') (0x1234, '00 0d 12 34'),
assert mpint(0x9a378f9b2e332a7) == _b('00 00 00 08 09 a3 78 f9 b2 e3 32 a7') (0x12345, '00 11 01 23 45')]
assert mpint(-0x1234) == _b('00 00 00 02 ed cc') for p in tc:
assert mpint(-0xdeadbeef) == _b('00 00 00 05 ff 21 52 41 11') assert mpint1w(p[0]) == self._b(p[1])
assert mpint(-0x80) == _b('00 00 00 01 80') assert mpint1r(self._b(p[1])) == p[0]
def test_mpint2_read(self): def test_mpint2(self):
rbuf, _b = self.rbuf, self._b mpint2w = lambda x: self.wbuf().write_mpint2(x).write_flush()
mpint = lambda x: rbuf(x).read_mpint2() mpint2r = lambda x: self.rbuf(x).read_mpint2()
assert mpint(_b('00 00 00 00')) == 0x00 tc = [(0x0, '00 00 00 00'),
assert mpint(_b('00 00 00 02 00 80')) == 0x80 (0x80, '00 00 00 02 00 80'),
assert mpint(_b('00 00 00 08 09 a3 78 f9 b2 e3 32 a7')) == 0x9a378f9b2e332a7 (0x9a378f9b2e332a7, '00 00 00 08 09 a3 78 f9 b2 e3 32 a7'),
assert mpint(_b('00 00 00 02 ed cc')) == -0x1234 (-0x1234, '00 00 00 02 ed cc'),
assert mpint(_b('00 00 00 05 ff 21 52 41 11')) == -0xdeadbeef (-0xdeadbeef, '00 00 00 05 ff 21 52 41 11'),
assert mpint(_b('00 00 00 01 80')) == -0x80 (-0x8000, '00 00 00 02 80 00'),
assert mpint(_b('00 00 00 02 ff 80')) == -0x80 (-0x80, '00 00 00 01 80')]
for p in tc:
assert mpint2w(p[0]) == self._b(p[1])
assert mpint2r(self._b(p[1])) == p[0]
assert mpint2r(self._b('00 00 00 02 ff 80')) == -0x80