import string, re
def encode_name(name, type, scope = None):
"""
Perform first and second level encoding of name as specified in RFC 1001 (Section 4)
"""
if name == '*':
name = name + '\0' * 15
elif len(name) > 15:
name = name[:15] + chr(type)
else:
name = string.ljust(name, 15) + chr(type)
def _do_first_level_encoding(m):
s = ord(m.group(0))
return string.uppercase[s >> 4] + string.uppercase[s & 0x0f]
encoded_name = chr(len(name) * 2) + re.sub('.', _do_first_level_encoding, name)
if scope:
encoded_scope = ''
for s in string.split(scope, '.'):
encoded_scope = encoded_scope + chr(len(s)) + s
return encoded_name + encoded_scope + '\0'
else:
return encoded_name + '\0'
def decode_name(name):
name_length = ord(name[0])
assert name_length == 32
def _do_first_level_decoding(m):
s = m.group(0)
return chr(((ord(s[0]) - ord('A')) << 4) | (ord(s[1]) - ord('A')))
decoded_name = re.sub('..', _do_first_level_decoding, name[1:33])
if name[33] == '\0':
return 34, decoded_name, ''
else:
decoded_domain = ''
offset = 34
while 1:
domain_length = ord(name[offset])
if domain_length == 0:
break
decoded_domain = '.' + name[offset:offset + domain_length]
offset = offset + domain_length
return offset + 1, decoded_name, decoded_domain