commit 67c86d3494e5f6d846bbe7117f46efa6cf89aedb
Author: John-Mark Gurney <jmg@funkthat.com>
Date:   Sat Feb 13 00:44:43 2016 -0800

    add inital version of this code..
    
    only special float values work..
    
    various time formats not supported..
    
    [git-p4: depot-paths = "//depot/python/pypasn1/main/": change = 1817]

diff --git a/pasn1.py b/pasn1.py
new file mode 100644
index 0000000..94ec31d
--- /dev/null
+++ b/pasn1.py
@@ -0,0 +1,346 @@
+#!/usr/bin/env python
+
+# A Pure Python ASN.1 encoder/decoder w/ a calling interface in the spirit
+# of pickle.  It will automaticly do the correct thing if possible.
+#
+# This uses a profile of ASN.1.
+#
+# All lengths must be specified.  That is that End-of-contents octets
+# MUST not be used.  The shorted form of length encoding MUST be used.
+# A longer length encoding MUST be rejected.
+
+import pdb
+import math
+import sys
+import unittest
+
+def _numtostr(n):
+	hs = '%x' % n
+	if len(hs) & 1 == 1:
+		hs = '0' + hs
+	bs = hs.decode('hex')
+
+	return bs
+
+def _encodelen(l):
+	'''Takes l as a length value, and returns a byte string that
+	represents l per ASN.1 rules.'''
+
+	if l < 128:
+		return chr(l)
+
+	bs = _numtostr(l)
+	return chr(len(bs) | 0x80) + bs
+
+def _decodelen(d, pos=0):
+	'''Returns the length, and number of bytes required.'''
+
+	odp = ord(d[pos])
+	if odp < 128:
+		return ord(d[pos]), 1
+	else:
+		l = odp & 0x7f
+		return int(d[pos + 1:pos + 1 + l].encode('hex'), 16), l + 1
+
+class Test_codelen(unittest.TestCase):
+	_testdata = [
+		(2, '\x02'),
+		(127, '\x7f'),
+		(128, '\x81\x80'),
+		(255, '\x81\xff'),
+		(256, '\x82\x01\x00'),
+		(65536-1, '\x82\xff\xff'),
+		(65536, '\x83\x01\x00\x00'),
+	]
+
+	def test_el(self):
+		for i, j in self._testdata:
+			self.assertEqual(_encodelen(i), j)
+			self.assertEqual(_decodelen(j), (i, len(j)))
+
+def _splitfloat(f):
+	m, e = math.frexp(f)
+	# XXX - less than ideal
+	while m != math.trunc(m):
+		m *= 2
+		e -= 1
+
+	return m, e
+
+class TestSplitFloat(unittest.TestCase):
+	def test_sf(self):
+		for a, b in [ (0x2421, -32), (0x5382f, 238),
+		    (0x1fa8c3b094adf1, 971) ]:
+			self.assertEqual(_splitfloat(a * 2**b), (a, b))
+
+class ASN1Object:
+	def __init__(self, tag):
+		self._tag = tag
+
+class ASN1Coder(object):
+	def __init__(self):
+		pass
+
+	_typemap = {
+		bool: 'bool',
+		dict: 'dict',
+		float: 'float',
+		int: 'int',
+		list: 'list',
+		long: 'int',
+		set: 'set',
+		str: 'bytes',
+		type(None): 'none',
+		unicode: 'unicode',
+	}
+	_tagmap = {
+		'\x01':	'bool',
+		'\x02':	'int',
+		'\x04':	'bytes',
+		'\x05':	'none',
+		'\x09':	'float',
+		'\x0c':	'unicode',
+		'\x30':	'list',
+		'\x31': 'set',
+		'\xc0':	'dict',
+	}
+
+	_typetag = dict((v, k) for k, v in _tagmap.iteritems())
+
+	@staticmethod
+	def enc_int(obj):
+		l = obj.bit_length()
+		l += 1	# space for sign bit
+
+		l = (l + 7) // 8
+
+		if obj < 0:
+			obj += 1 << (l * 8) # twos-complement conversion
+
+		v = _numtostr(obj)
+		if len(v) != l:
+			# XXX - is this a problem for signed values?
+			v = '\x00' + v # add sign octect
+
+		return _encodelen(l) + v
+
+	@staticmethod
+	def dec_int(d, pos, end):
+		if pos == end:
+			return 0, end
+
+		v = int(d[pos:end].encode('hex'), 16)
+		av = 1 << ((end - pos) * 8 - 1) # sign bit
+		if v > av:
+			v -= av * 2 # twos-complement conversion
+
+		return v, end
+
+	@staticmethod
+	def enc_bool(obj):
+		return '\x01' + chr(obj)
+
+	def dec_bool(self, d, pos, end):
+		return bool(self.dec_int(d, pos, end)[0]), end
+
+	@staticmethod
+	def enc_none(obj):
+		return '\x00'
+
+	@staticmethod
+	def dec_none(d, pos, end):
+		return None, end
+
+	def enc_dict(self, obj):
+		#it = list(obj.iteritems())
+		#it.sort()
+		r = ''.join(self.dumps(k) + self.dumps(v) for k, v in obj.iteritems())
+		return _encodelen(len(r)) + r
+
+	def dec_dict(self, d, pos, end):
+		r = {}
+		while pos < end:
+			k, kend = self._loads(d, pos, end)
+			v, vend = self._loads(d, kend, end)
+
+			r[k] = v
+			pos = vend
+
+		return r, vend
+
+	def enc_set(self, obj):
+		r = ''.join(self.dumps(x) for x in obj)
+		return _encodelen(len(r)) + r
+
+	def dec_set(self, d, pos, end):
+		r, end = self.dec_list(d, pos, end)
+		return set(r), end
+
+	def enc_list(self, obj):
+		r = ''.join(self.dumps(x) for x in obj)
+		return _encodelen(len(r)) + r
+
+	def dec_list(self, d, pos, end):
+		r = []
+		while pos < end:
+			v, vend = self._loads(d, pos, end)
+			r.append(v)
+			pos = vend
+
+		return r, vend
+
+	@staticmethod
+	def enc_bytes(obj):
+		return _encodelen(len(obj)) + obj
+
+	@staticmethod
+	def dec_bytes(d, pos, end):
+		return d[pos:end], end
+
+	@staticmethod
+	def enc_unicode(obj):
+		encobj = obj.encode('utf-8')
+		return _encodelen(len(encobj)) + encobj
+
+	def dec_unicode(self, d, pos, end):
+		return d[pos:end].decode('utf-8'), end
+
+	@staticmethod
+	def enc_float(obj):
+		s = math.copysign(1, obj)
+		if math.isnan(obj):
+			return _encodelen(1) + chr(0b01000010)
+		elif math.isinf(obj):
+			if s == 1:
+				return _encodelen(1) + chr(0b01000000)
+			else:
+				return _encodelen(1) + chr(0b01000001)
+		elif obj == 0:
+			if s == 1:
+				return _encodelen(0)
+			else:
+				return _encodelen(1) + chr(0b01000011)
+
+		m, e = _splitfloat(obj)
+
+		# Binary encoding
+		val = 0x80
+		if m < 0:
+			val |= 0x40
+			m = -m
+		# Base 2
+		# XXX - negative e
+		el = (e.bit_length() + 7) // 8
+		if el > 3:
+			v = 0x3
+			encexp = _encodelen(el) + _numtostr(e)
+		else:
+			v = el - 1
+			encexp = _numtostr(e)
+
+		return chr(val) + encexp + _numtostr(m)
+
+	@staticmethod
+	def dec_float(d, pos, end):
+		if pos == end:
+			return float(0), end
+
+		v = ord(d[pos])
+		if v == 0b01000000:
+			return float('inf'), end
+		elif v == 0b01000001:
+			return float('-inf'), end
+		elif v == 0b01000010:
+			return float('nan'), end
+		elif v == 0b01000011:
+			return float('-0'), end
+		#elif v & 0b11000000 == 0b01000000:
+		#	raise ValueError('invalid encoding')
+
+		print 'df:', `d, pos, end`
+
+		raise NotImplementedError
+
+	def dumps(self, obj):
+		tf = self._typemap[type(obj)]
+		fun = getattr(self, 'enc_%s' % tf)
+		return self._typetag[tf] + fun(obj)
+
+	def _loads(self, data, pos, end):
+		tag = data[pos]
+		l, b = _decodelen(data, pos + 1)
+		if len(data) < pos + 1 + b + l:
+			print `data, pos, end, l, b`
+			raise ValueError('string not long enough')
+
+		# XXX - enforce that len(data) == end?
+		end = pos + 1 + b + l
+
+		t = self._tagmap[tag]
+		fun = getattr(self, 'dec_%s' % t)
+		return fun(data, pos + 1 + b, end)
+
+	def loads(self, data, pos=0, end=None, consume=False):
+		if end is None:
+			end = len(data)
+		r, e = self._loads(data, pos, end)
+
+		if consume and e != end:
+			raise ValueError('entire string not consumed')
+		return r
+
+_coder = ASN1Coder()
+dumps = _coder.dumps
+loads = _coder.loads
+
+class TestCode(unittest.TestCase):
+	def test_primv(self):
+		self.assertEqual(dumps(-257), '0202feff'.decode('hex'))
+		self.assertEqual(dumps(-256), '0202ff00'.decode('hex'))
+		self.assertEqual(dumps(-255), '0202ff01'.decode('hex'))
+		self.assertEqual(dumps(-1), '0201ff'.decode('hex'))
+		self.assertEqual(dumps(5), '020105'.decode('hex'))
+		self.assertEqual(dumps(128), '02020080'.decode('hex'))
+		self.assertEqual(dumps(256), '02020100'.decode('hex'))
+
+		self.assertEqual(dumps(False), '010100'.decode('hex'))
+		self.assertEqual(dumps(True), '010101'.decode('hex'))
+
+		self.assertEqual(dumps(None), '0500'.decode('hex'))
+
+	def test_consume(self):
+		b = dumps(5)
+		self.assertRaises(ValueError, loads, b + '398473', consume=True)
+
+		# XXX - still possible that an internal data member
+		# doesn't consume all
+
+	def test_nan(self):
+		s = dumps(float('nan'))
+		v = loads(s)
+		self.assertTrue(math.isnan(v))
+
+	def test_dumps(self):
+		for i in [ None,
+		    True, False,
+		    -1, 0, 1, 255, 256, -255, -256, 23498732498723, -2398729387234, (1<<2383) + 23984734, (-1<<1983) + 23984723984,
+		    float(0), float('-0'), float('inf'), float('-inf'),
+		    'weoifjwef',
+		    u'\U0001f4a9',
+		    set((1,2,3)), set((1,'sjlfdkj', None, float('inf'))),
+		    ]:
+			s = dumps(i)
+			o = loads(s)
+			self.assertEqual(i, o)
+
+		print 'done'
+		tobj = { 1: 'dflkj', 5: u'sdlkfj', 'float': 1, 'largeint': 1<<342, 'list': [ 1, 2, u'str', 'str' ] }
+
+		out = dumps(tobj)
+		self.assertEqual(tobj, loads(out))
+
+	def test_loads(self):
+		self.assertRaises(ValueError, loads, '\x00\x02\x00')
+
+if __name__ == '__main__':
+	pass