2003-04-18 07:39:54 -03:00
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# This module implements the RFCs 3490 (IDNA) and 3491 (Nameprep)
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import stringprep, unicodedata, re, codecs
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# IDNA section 3.1
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dots = re.compile(u"[\u002E\u3002\uFF0E\uFF61]")
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# IDNA section 5
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ace_prefix = "xn--"
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uace_prefix = unicode(ace_prefix, "ascii")
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# This assumes query strings, so AllowUnassigned is true
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def nameprep(label):
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# Map
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newlabel = []
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for c in label:
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if stringprep.in_table_b1(c):
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# Map to nothing
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continue
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newlabel.append(stringprep.map_table_b2(c))
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label = u"".join(newlabel)
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2003-04-24 13:02:54 -03:00
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2003-04-18 07:39:54 -03:00
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# Normalize
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label = unicodedata.normalize("NFKC", label)
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2003-04-24 13:02:54 -03:00
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2003-04-18 07:39:54 -03:00
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# Prohibit
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for c in label:
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if stringprep.in_table_c12(c) or \
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stringprep.in_table_c22(c) or \
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stringprep.in_table_c3(c) or \
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stringprep.in_table_c4(c) or \
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stringprep.in_table_c5(c) or \
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stringprep.in_table_c6(c) or \
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stringprep.in_table_c7(c) or \
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stringprep.in_table_c8(c) or \
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stringprep.in_table_c9(c):
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raise UnicodeError, "Invalid character %s" % repr(c)
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# Check bidi
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RandAL = map(stringprep.in_table_d1, label)
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for c in RandAL:
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if c:
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# There is a RandAL char in the string. Must perform further
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# tests:
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# 1) The characters in section 5.8 MUST be prohibited.
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# This is table C.8, which was already checked
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# 2) If a string contains any RandALCat character, the string
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# MUST NOT contain any LCat character.
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if filter(stringprep.in_table_d2, label):
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raise UnicodeError, "Violation of BIDI requirement 2"
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# 3) If a string contains any RandALCat character, a
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# RandALCat character MUST be the first character of the
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# string, and a RandALCat character MUST be the last
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# character of the string.
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if not RandAL[0] or not RandAL[-1]:
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raise UnicodeError, "Violation of BIDI requirement 3"
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return label
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def ToASCII(label):
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try:
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# Step 1: try ASCII
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label = label.encode("ascii")
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except UnicodeError:
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pass
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else:
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# Skip to step 3: UseSTD3ASCIIRules is false, so
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# Skip to step 8.
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if 0 < len(label) < 64:
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return label
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raise UnicodeError, "label too long"
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# Step 2: nameprep
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label = nameprep(label)
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# Step 3: UseSTD3ASCIIRules is false
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# Step 4: try ASCII
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try:
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label = label.encode("ascii")
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except UnicodeError:
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pass
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else:
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# Skip to step 8.
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if 0 < len(label) < 64:
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return label
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raise UnicodeError, "label too long"
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# Step 5: Check ACE prefix
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if label.startswith(uace_prefix):
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raise UnicodeError, "Label starts with ACE prefix"
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# Step 6: Encode with PUNYCODE
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label = label.encode("punycode")
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# Step 7: Prepend ACE prefix
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label = ace_prefix + label
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# Step 8: Check size
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if 0 < len(label) < 64:
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return label
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raise UnicodeError, "label too long"
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def ToUnicode(label):
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# Step 1: Check for ASCII
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if isinstance(label, str):
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pure_ascii = True
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else:
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try:
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label = label.encode("ascii")
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pure_ascii = True
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except UnicodeError:
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pure_ascii = False
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if not pure_ascii:
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# Step 2: Perform nameprep
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label = nameprep(label)
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# It doesn't say this, but apparently, it should be ASCII now
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try:
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label = label.encode("ascii")
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except UnicodeError:
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raise UnicodeError, "Invalid character in IDN label"
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# Step 3: Check for ACE prefix
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if not label.startswith(ace_prefix):
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return unicode(label, "ascii")
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# Step 4: Remove ACE prefix
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label1 = label[len(ace_prefix):]
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# Step 5: Decode using PUNYCODE
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result = label1.decode("punycode")
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# Step 6: Apply ToASCII
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label2 = ToASCII(result)
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# Step 7: Compare the result of step 6 with the one of step 3
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# label2 will already be in lower case.
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if label.lower() != label2:
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raise UnicodeError, ("IDNA does not round-trip", label, label2)
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# Step 8: return the result of step 5
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return result
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2003-04-24 13:02:54 -03:00
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2003-04-18 07:39:54 -03:00
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### Codec APIs
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class Codec(codecs.Codec):
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def encode(self,input,errors='strict'):
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if errors != 'strict':
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# IDNA is quite clear that implementations must be strict
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raise UnicodeError, "unsupported error handling "+errors
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result = []
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for label in dots.split(input):
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result.append(ToASCII(label))
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# Join with U+002E
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return ".".join(result), len(input)
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def decode(self,input,errors='strict'):
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2003-04-18 07:39:54 -03:00
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if errors != 'strict':
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raise UnicodeError, "Unsupported error handling "+errors
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# IDNA allows decoding to operate on Unicode strings, too.
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if isinstance(input, unicode):
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labels = dots.split(input)
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else:
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# Must be ASCII string
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unicode(input, "ascii")
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labels = input.split(".")
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result = []
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for label in labels:
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result.append(ToUnicode(label))
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return u".".join(result), len(input)
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class StreamWriter(Codec,codecs.StreamWriter):
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pass
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class StreamReader(Codec,codecs.StreamReader):
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pass
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### encodings module API
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def getregentry():
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return (Codec().encode,Codec().decode,StreamReader,StreamWriter)
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