def decode_oid(length, message):
"""decode ASN.1 object ID"""
oid = []
# get the first subid
subid = ord(message[0])
oid.append(subid // 40)
oid.append(subid % 40)
index = 1
# loop through the rest
while index < length:
# get a subid
subid = ord(message[index])
if subid < 128:
oid.append(subid)
index = index + 1
else:
# construct subid from a number of octets
next = subid
subid = 0
while next >= 128:
# collect subid
subid = (subid << 7) + (next & 0x7F)
# take next octet
index = index + 1
next = ord(message[index])
# just for sure
if index > length:
return bad_integer
# append a subid to oid list
subid = (subid << 7) + next
oid.append(subid)
index = index + 1
# return objid
return Basetypes.OBJECT_IDENTIFIER(oid)
