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# This module implements the RFCs 3490 (IDNA) and 3491 (Nameprep)
import stringprep, unicodedata, re, codecs
# IDNA section 3.1
dots = re.compile(u"[\u002E\u3002\uFF0E\uFF61]")
# IDNA section 5
ace_prefix = "xn--"
uace_prefix = unicode(ace_prefix, "ascii")
# This assumes query strings, so AllowUnassigned is true
def nameprep(label):
# Map
newlabel = []
for c in label:
if stringprep.in_table_b1(c):
# Map to nothing
continue
newlabel.append(stringprep.map_table_b2(c))
label = u"".join(newlabel)
# Normalize
label = unicodedata.normalize("NFKC", label)
# Prohibit
for c in label:
if stringprep.in_table_c12(c) or \
stringprep.in_table_c22(c) or \
stringprep.in_table_c3(c) or \
stringprep.in_table_c4(c) or \
stringprep.in_table_c5(c) or \
stringprep.in_table_c6(c) or \
stringprep.in_table_c7(c) or \
stringprep.in_table_c8(c) or \
stringprep.in_table_c9(c):
raise UnicodeError, "Invalid character %s" % repr(c)
# Check bidi
RandAL = map(stringprep.in_table_d1, label)
for c in RandAL:
if c:
# There is a RandAL char in the string. Must perform further
# tests:
# 1) The characters in section 5.8 MUST be prohibited.
# This is table C.8, which was already checked
# 2) If a string contains any RandALCat character, the string
# MUST NOT contain any LCat character.
if filter(stringprep.in_table_d2, label):
raise UnicodeError, "Violation of BIDI requirement 2"
# 3) If a string contains any RandALCat character, a
# RandALCat character MUST be the first character of the
# string, and a RandALCat character MUST be the last
# character of the string.
if not RandAL[0] or not RandAL[-1]:
raise UnicodeError, "Violation of BIDI requirement 3"
return label
def ToASCII(label):
try:
# Step 1: try ASCII
label = label.encode("ascii")
except UnicodeError:
pass
else:
# Skip to step 3: UseSTD3ASCIIRules is false, so
# Skip to step 8.
if 0 < len(label) < 64:
return label
raise UnicodeError, "label too long"
# Step 2: nameprep
label = nameprep(label)
# Step 3: UseSTD3ASCIIRules is false
# Step 4: try ASCII
try:
label = label.encode("ascii")
except UnicodeError:
pass
else:
# Skip to step 8.
if 0 < len(label) < 64:
return label
raise UnicodeError, "label too long"
# Step 5: Check ACE prefix
if label.startswith(uace_prefix):
raise UnicodeError, "Label starts with ACE prefix"
# Step 6: Encode with PUNYCODE
label = label.encode("punycode")
# Step 7: Prepend ACE prefix
label = ace_prefix + label
# Step 8: Check size
if 0 < len(label) < 64:
return label
raise UnicodeError, "label too long"
def ToUnicode(label):
# Step 1: Check for ASCII
if isinstance(label, str):
pure_ascii = True
else:
try:
label = label.encode("ascii")
pure_ascii = True
except UnicodeError:
pure_ascii = False
if not pure_ascii:
# Step 2: Perform nameprep
label = nameprep(label)
# It doesn't say this, but apparently, it should be ASCII now
try:
label = label.encode("ascii")
except UnicodeError:
raise UnicodeError, "Invalid character in IDN label"
# Step 3: Check for ACE prefix
if not label.startswith(ace_prefix):
return unicode(label, "ascii")
# Step 4: Remove ACE prefix
label1 = label[len(ace_prefix):]
# Step 5: Decode using PUNYCODE
result = label1.decode("punycode")
# Step 6: Apply ToASCII
label2 = ToASCII(result)
# Step 7: Compare the result of step 6 with the one of step 3
# label2 will already be in lower case.
if label.lower() != label2:
raise UnicodeError, ("IDNA does not round-trip", label, label2)
# Step 8: return the result of step 5
return result
### Codec APIs
class Codec(codecs.Codec):
def encode(self,input,errors='strict'):
if errors != 'strict':
# IDNA is quite clear that implementations must be strict
raise UnicodeError, "unsupported error handling "+errors
result = []
labels = dots.split(input)
if labels and len(labels[-1])==0:
trailing_dot = '.'
del labels[-1]
else:
trailing_dot = ''
for label in labels:
result.append(ToASCII(label))
# Join with U+002E
return ".".join(result)+trailing_dot, len(input)
def decode(self,input,errors='strict'):
if errors != 'strict':
raise UnicodeError, "Unsupported error handling "+errors
# IDNA allows decoding to operate on Unicode strings, too.
if isinstance(input, unicode):
labels = dots.split(input)
else:
# Must be ASCII string
input = str(input)
unicode(input, "ascii")
labels = input.split(".")
if labels and len(labels[-1]) == 0:
trailing_dot = u'.'
del labels[-1]
else:
trailing_dot = u''
result = []
for label in labels:
result.append(ToUnicode(label))
return u".".join(result)+trailing_dot, len(input)
class StreamWriter(Codec,codecs.StreamWriter):
pass
class StreamReader(Codec,codecs.StreamReader):
pass
### encodings module API
def getregentry():
return (Codec().encode,Codec().decode,StreamReader,StreamWriter)
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