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-rw-r--r--net/tools/testserver/asn1.py165
1 files changed, 165 insertions, 0 deletions
diff --git a/net/tools/testserver/asn1.py b/net/tools/testserver/asn1.py
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+++ b/net/tools/testserver/asn1.py
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+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This file implements very minimal ASN.1, DER serialization.
+
+import types
+
+
+def ToDER(obj):
+ '''ToDER converts the given object into DER encoding'''
+ if type(obj) == types.NoneType:
+ # None turns into NULL
+ return TagAndLength(5, 0)
+ if type(obj) == types.StringType:
+ # Strings are PRINTABLESTRING
+ return TagAndLength(19, len(obj)) + obj
+ if type(obj) == types.BooleanType:
+ val = "\x00"
+ if obj:
+ val = "\xff"
+ return TagAndLength(1, 1) + val
+ if type(obj) == types.IntType or type(obj) == types.LongType:
+ big_endian = []
+ val = obj
+ while val != 0:
+ big_endian.append(val & 0xff)
+ val >>= 8
+
+ if len(big_endian) == 0 or big_endian[-1] >= 128:
+ big_endian.append(0)
+
+ big_endian.reverse()
+ return TagAndLength(2, len(big_endian)) + ToBytes(big_endian)
+
+ return obj.ToDER()
+
+
+def ToBytes(array_of_bytes):
+ '''ToBytes converts the array of byte values into a binary string'''
+ return ''.join([chr(x) for x in array_of_bytes])
+
+
+def TagAndLength(tag, length):
+ der = [tag]
+ if length < 128:
+ der.append(length)
+ elif length < 256:
+ der.append(0x81)
+ der.append(length)
+ elif length < 65535:
+ der.append(0x82)
+ der.append(length >> 8)
+ der.append(length & 0xff)
+ else:
+ assert False
+
+ return ToBytes(der)
+
+
+class Raw(object):
+ '''Raw contains raw DER encoded bytes that are used verbatim'''
+ def __init__(self, der):
+ self.der = der
+
+ def ToDER(self):
+ return self.der
+
+
+class Explicit(object):
+ '''Explicit prepends an explicit tag'''
+ def __init__(self, tag, child):
+ self.tag = tag
+ self.child = child
+
+ def ToDER(self):
+ der = ToDER(self.child)
+ tag = self.tag
+ tag |= 0x80 # content specific
+ tag |= 0x20 # complex
+ return TagAndLength(tag, len(der)) + der
+
+
+class ENUMERATED(object):
+ def __init__(self, value):
+ self.value = value
+
+ def ToDER(self):
+ return TagAndLength(10, 1) + chr(self.value)
+
+
+class SEQUENCE(object):
+ def __init__(self, children):
+ self.children = children
+
+ def ToDER(self):
+ der = ''.join([ToDER(x) for x in self.children])
+ return TagAndLength(0x30, len(der)) + der
+
+
+class SET(object):
+ def __init__(self, children):
+ self.children = children
+
+ def ToDER(self):
+ der = ''.join([ToDER(x) for x in self.children])
+ return TagAndLength(0x31, len(der)) + der
+
+
+class OCTETSTRING(object):
+ def __init__(self, val):
+ self.val = val
+
+ def ToDER(self):
+ return TagAndLength(4, len(self.val)) + self.val
+
+
+class OID(object):
+ def __init__(self, parts):
+ self.parts = parts
+
+ def ToDER(self):
+ if len(self.parts) < 2 or self.parts[0] > 6 or self.parts[1] >= 40:
+ assert False
+
+ der = [self.parts[0]*40 + self.parts[1]]
+ for x in self.parts[2:]:
+ if x == 0:
+ der.append(0)
+ else:
+ octets = []
+ while x != 0:
+ v = x & 0x7f
+ if len(octets) > 0:
+ v |= 0x80
+ octets.append(v)
+ x >>= 7
+ octets.reverse()
+ der = der + octets
+
+ return TagAndLength(6, len(der)) + ToBytes(der)
+
+
+class UTCTime(object):
+ def __init__(self, time_str):
+ self.time_str = time_str
+
+ def ToDER(self):
+ return TagAndLength(23, len(self.time_str)) + self.time_str
+
+
+class GeneralizedTime(object):
+ def __init__(self, time_str):
+ self.time_str = time_str
+
+ def ToDER(self):
+ return TagAndLength(24, len(self.time_str)) + self.time_str
+
+
+class BitString(object):
+ def __init__(self, bits):
+ self.bits = bits
+
+ def ToDER(self):
+ return TagAndLength(3, 1 + len(self.bits)) + "\x00" + self.bits