source: python/trunk/Lib/encodings/idna.py@ 602

Last change on this file since 602 was 2, checked in by Yuri Dario, 15 years ago

Initial import for vendor code.
  • Property svn:eol-style set to native
File size: 8.3 KB
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1# This module implements the RFCs 3490 (IDNA) and 3491 (Nameprep)
2
3import stringprep, re, codecs
4from unicodedata import ucd_3_2_0 as unicodedata
5
6# IDNA section 3.1
7dots = re.compile(u"[\u002E\u3002\uFF0E\uFF61]")
8
9# IDNA section 5
10ace_prefix = "xn--"
11uace_prefix = unicode(ace_prefix, "ascii")
12
13# This assumes query strings, so AllowUnassigned is true
14def nameprep(label):
15 # Map
16 newlabel = []
17 for c in label:
18 if stringprep.in_table_b1(c):
19 # Map to nothing
20 continue
21 newlabel.append(stringprep.map_table_b2(c))
22 label = u"".join(newlabel)
23
24 # Normalize
25 label = unicodedata.normalize("NFKC", label)
26
27 # Prohibit
28 for c in label:
29 if stringprep.in_table_c12(c) or \
30 stringprep.in_table_c22(c) or \
31 stringprep.in_table_c3(c) or \
32 stringprep.in_table_c4(c) or \
33 stringprep.in_table_c5(c) or \
34 stringprep.in_table_c6(c) or \
35 stringprep.in_table_c7(c) or \
36 stringprep.in_table_c8(c) or \
37 stringprep.in_table_c9(c):
38 raise UnicodeError("Invalid character %r" % c)
39
40 # Check bidi
41 RandAL = map(stringprep.in_table_d1, label)
42 for c in RandAL:
43 if c:
44 # There is a RandAL char in the string. Must perform further
45 # tests:
46 # 1) The characters in section 5.8 MUST be prohibited.
47 # This is table C.8, which was already checked
48 # 2) If a string contains any RandALCat character, the string
49 # MUST NOT contain any LCat character.
50 if filter(stringprep.in_table_d2, label):
51 raise UnicodeError("Violation of BIDI requirement 2")
52
53 # 3) If a string contains any RandALCat character, a
54 # RandALCat character MUST be the first character of the
55 # string, and a RandALCat character MUST be the last
56 # character of the string.
57 if not RandAL[0] or not RandAL[-1]:
58 raise UnicodeError("Violation of BIDI requirement 3")
59
60 return label
61
62def ToASCII(label):
63 try:
64 # Step 1: try ASCII
65 label = label.encode("ascii")
66 except UnicodeError:
67 pass
68 else:
69 # Skip to step 3: UseSTD3ASCIIRules is false, so
70 # Skip to step 8.
71 if 0 < len(label) < 64:
72 return label
73 raise UnicodeError("label empty or too long")
74
75 # Step 2: nameprep
76 label = nameprep(label)
77
78 # Step 3: UseSTD3ASCIIRules is false
79 # Step 4: try ASCII
80 try:
81 label = label.encode("ascii")
82 except UnicodeError:
83 pass
84 else:
85 # Skip to step 8.
86 if 0 < len(label) < 64:
87 return label
88 raise UnicodeError("label empty or too long")
89
90 # Step 5: Check ACE prefix
91 if label.startswith(uace_prefix):
92 raise UnicodeError("Label starts with ACE prefix")
93
94 # Step 6: Encode with PUNYCODE
95 label = label.encode("punycode")
96
97 # Step 7: Prepend ACE prefix
98 label = ace_prefix + label
99
100 # Step 8: Check size
101 if 0 < len(label) < 64:
102 return label
103 raise UnicodeError("label empty or too long")
104
105def ToUnicode(label):
106 # Step 1: Check for ASCII
107 if isinstance(label, str):
108 pure_ascii = True
109 else:
110 try:
111 label = label.encode("ascii")
112 pure_ascii = True
113 except UnicodeError:
114 pure_ascii = False
115 if not pure_ascii:
116 # Step 2: Perform nameprep
117 label = nameprep(label)
118 # It doesn't say this, but apparently, it should be ASCII now
119 try:
120 label = label.encode("ascii")
121 except UnicodeError:
122 raise UnicodeError("Invalid character in IDN label")
123 # Step 3: Check for ACE prefix
124 if not label.startswith(ace_prefix):
125 return unicode(label, "ascii")
126
127 # Step 4: Remove ACE prefix
128 label1 = label[len(ace_prefix):]
129
130 # Step 5: Decode using PUNYCODE
131 result = label1.decode("punycode")
132
133 # Step 6: Apply ToASCII
134 label2 = ToASCII(result)
135
136 # Step 7: Compare the result of step 6 with the one of step 3
137 # label2 will already be in lower case.
138 if label.lower() != label2:
139 raise UnicodeError("IDNA does not round-trip", label, label2)
140
141 # Step 8: return the result of step 5
142 return result
143
144### Codec APIs
145
146class Codec(codecs.Codec):
147 def encode(self,input,errors='strict'):
148
149 if errors != 'strict':
150 # IDNA is quite clear that implementations must be strict
151 raise UnicodeError("unsupported error handling "+errors)
152
153 if not input:
154 return "", 0
155
156 result = []
157 labels = dots.split(input)
158 if labels and len(labels[-1])==0:
159 trailing_dot = '.'
160 del labels[-1]
161 else:
162 trailing_dot = ''
163 for label in labels:
164 result.append(ToASCII(label))
165 # Join with U+002E
166 return ".".join(result)+trailing_dot, len(input)
167
168 def decode(self,input,errors='strict'):
169
170 if errors != 'strict':
171 raise UnicodeError("Unsupported error handling "+errors)
172
173 if not input:
174 return u"", 0
175
176 # IDNA allows decoding to operate on Unicode strings, too.
177 if isinstance(input, unicode):
178 labels = dots.split(input)
179 else:
180 # Must be ASCII string
181 input = str(input)
182 unicode(input, "ascii")
183 labels = input.split(".")
184
185 if labels and len(labels[-1]) == 0:
186 trailing_dot = u'.'
187 del labels[-1]
188 else:
189 trailing_dot = u''
190
191 result = []
192 for label in labels:
193 result.append(ToUnicode(label))
194
195 return u".".join(result)+trailing_dot, len(input)
196
197class IncrementalEncoder(codecs.BufferedIncrementalEncoder):
198 def _buffer_encode(self, input, errors, final):
199 if errors != 'strict':
200 # IDNA is quite clear that implementations must be strict
201 raise UnicodeError("unsupported error handling "+errors)
202
203 if not input:
204 return ("", 0)
205
206 labels = dots.split(input)
207 trailing_dot = u''
208 if labels:
209 if not labels[-1]:
210 trailing_dot = '.'
211 del labels[-1]
212 elif not final:
213 # Keep potentially unfinished label until the next call
214 del labels[-1]
215 if labels:
216 trailing_dot = '.'
217
218 result = []
219 size = 0
220 for label in labels:
221 result.append(ToASCII(label))
222 if size:
223 size += 1
224 size += len(label)
225
226 # Join with U+002E
227 result = ".".join(result) + trailing_dot
228 size += len(trailing_dot)
229 return (result, size)
230
231class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
232 def _buffer_decode(self, input, errors, final):
233 if errors != 'strict':
234 raise UnicodeError("Unsupported error handling "+errors)
235
236 if not input:
237 return (u"", 0)
238
239 # IDNA allows decoding to operate on Unicode strings, too.
240 if isinstance(input, unicode):
241 labels = dots.split(input)
242 else:
243 # Must be ASCII string
244 input = str(input)
245 unicode(input, "ascii")
246 labels = input.split(".")
247
248 trailing_dot = u''
249 if labels:
250 if not labels[-1]:
251 trailing_dot = u'.'
252 del labels[-1]
253 elif not final:
254 # Keep potentially unfinished label until the next call
255 del labels[-1]
256 if labels:
257 trailing_dot = u'.'
258
259 result = []
260 size = 0
261 for label in labels:
262 result.append(ToUnicode(label))
263 if size:
264 size += 1
265 size += len(label)
266
267 result = u".".join(result) + trailing_dot
268 size += len(trailing_dot)
269 return (result, size)
270
271class StreamWriter(Codec,codecs.StreamWriter):
272 pass
273
274class StreamReader(Codec,codecs.StreamReader):
275 pass
276
277### encodings module API
278
279def getregentry():
280 return codecs.CodecInfo(
281 name='idna',
282 encode=Codec().encode,
283 decode=Codec().decode,
284 incrementalencoder=IncrementalEncoder,
285 incrementaldecoder=IncrementalDecoder,
286 streamwriter=StreamWriter,
287 streamreader=StreamReader,
288 )
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