source file: /System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/email/quopriMIME.py
file stats: 142 lines, 27 executed: 19.0% covered
1. # Copyright (C) 2001,2002 Python Software Foundation 2. # Author: che@debian.org (Ben Gertzfield) 3. 4. """Quoted-printable content transfer encoding per RFCs 2045-2047. 5. 6. This module handles the content transfer encoding method defined in RFC 2045 7. to encode US ASCII-like 8-bit data called `quoted-printable'. It is used to 8. safely encode text that is in a character set similar to the 7-bit US ASCII 9. character set, but that includes some 8-bit characters that are normally not 10. allowed in email bodies or headers. 11. 12. Quoted-printable is very space-inefficient for encoding binary files; use the 13. email.base64MIME module for that instead. 14. 15. This module provides an interface to encode and decode both headers and bodies 16. with quoted-printable encoding. 17. 18. RFC 2045 defines a method for including character set information in an 19. `encoded-word' in a header. This method is commonly used for 8-bit real names 20. in To:/From:/Cc: etc. fields, as well as Subject: lines. 21. 22. This module does not do the line wrapping or end-of-line character 23. conversion necessary for proper internationalized headers; it only 24. does dumb encoding and decoding. To deal with the various line 25. wrapping issues, use the email.Header module. 26. """ 27. 28. import re 29. from string import hexdigits 30. from email.Utils import fix_eols 31. 32. CRLF = '\r\n' 33. NL = '\n' 34. 35. # See also Charset.py 36. MISC_LEN = 7 37. 38. hqre = re.compile(r'[^-a-zA-Z0-9!*+/ ]') 39. bqre = re.compile(r'[^ !-<>-~\t]') 40. 41. try: 42. True, False 43. except NameError: 44. True = 1 45. False = 0 46. 47. 48. 49. # Helpers 50. def header_quopri_check(c): 51. """Return True if the character should be escaped with header quopri.""" 52. return hqre.match(c) and True 53. 54. 55. def body_quopri_check(c): 56. """Return True if the character should be escaped with body quopri.""" 57. return bqre.match(c) and True 58. 59. 60. def header_quopri_len(s): 61. """Return the length of str when it is encoded with header quopri.""" 62. count = 0 63. for c in s: 64. if hqre.match(c): 65. count += 3 66. else: 67. count += 1 68. return count 69. 70. 71. def body_quopri_len(str): 72. """Return the length of str when it is encoded with body quopri.""" 73. count = 0 74. for c in str: 75. if bqre.match(c): 76. count += 3 77. else: 78. count += 1 79. return count 80. 81. 82. def _max_append(L, s, maxlen, extra=''): 83. if not L: 84. L.append(s.lstrip()) 85. elif len(L[-1]) + len(s) <= maxlen: 86. L[-1] += extra + s 87. else: 88. L.append(s.lstrip()) 89. 90. 91. def unquote(s): 92. """Turn a string in the form =AB to the ASCII character with value 0xab""" 93. return chr(int(s[1:3], 16)) 94. 95. 96. def quote(c): 97. return "=%02X" % ord(c) 98. 99. 100. 101. def header_encode(header, charset="iso-8859-1", keep_eols=False, 102. maxlinelen=76, eol=NL): 103. """Encode a single header line with quoted-printable (like) encoding. 104. 105. Defined in RFC 2045, this `Q' encoding is similar to quoted-printable, but 106. used specifically for email header fields to allow charsets with mostly 7 107. bit characters (and some 8 bit) to remain more or less readable in non-RFC 108. 2045 aware mail clients. 109. 110. charset names the character set to use to encode the header. It defaults 111. to iso-8859-1. 112. 113. The resulting string will be in the form: 114. 115. "=?charset?q?I_f=E2rt_in_your_g=E8n=E8ral_dire=E7tion?\\n 116. =?charset?q?Silly_=C8nglish_Kn=EEghts?=" 117. 118. with each line wrapped safely at, at most, maxlinelen characters (defaults 119. to 76 characters). If maxlinelen is None, the entire string is encoded in 120. one chunk with no splitting. 121. 122. End-of-line characters (\\r, \\n, \\r\\n) will be automatically converted 123. to the canonical email line separator \\r\\n unless the keep_eols 124. parameter is True (the default is False). 125. 126. Each line of the header will be terminated in the value of eol, which 127. defaults to "\\n". Set this to "\\r\\n" if you are using the result of 128. this function directly in email. 129. """ 130. # Return empty headers unchanged 131. if not header: 132. return header 133. 134. if not keep_eols: 135. header = fix_eols(header) 136. 137. # Quopri encode each line, in encoded chunks no greater than maxlinelen in 138. # length, after the RFC chrome is added in. 139. quoted = [] 140. if maxlinelen is None: 141. # An obnoxiously large number that's good enough 142. max_encoded = 100000 143. else: 144. max_encoded = maxlinelen - len(charset) - MISC_LEN - 1 145. 146. for c in header: 147. # Space may be represented as _ instead of =20 for readability 148. if c == ' ': 149. _max_append(quoted, '_', max_encoded) 150. # These characters can be included verbatim 151. elif not hqre.match(c): 152. _max_append(quoted, c, max_encoded) 153. # Otherwise, replace with hex value like =E2 154. else: 155. _max_append(quoted, "=%02X" % ord(c), max_encoded) 156. 157. # Now add the RFC chrome to each encoded chunk and glue the chunks 158. # together. BAW: should we be able to specify the leading whitespace in 159. # the joiner? 160. joiner = eol + ' ' 161. return joiner.join(['=?%s?q?%s?=' % (charset, line) for line in quoted]) 162. 163. 164. 165. def encode(body, binary=False, maxlinelen=76, eol=NL): 166. """Encode with quoted-printable, wrapping at maxlinelen characters. 167. 168. If binary is False (the default), end-of-line characters will be converted 169. to the canonical email end-of-line sequence \\r\\n. Otherwise they will 170. be left verbatim. 171. 172. Each line of encoded text will end with eol, which defaults to "\\n". Set 173. this to "\\r\\n" if you will be using the result of this function directly 174. in an email. 175. 176. Each line will be wrapped at, at most, maxlinelen characters (defaults to 177. 76 characters). Long lines will have the `soft linefeed' quoted-printable 178. character "=" appended to them, so the decoded text will be identical to 179. the original text. 180. """ 181. if not body: 182. return body 183. 184. if not binary: 185. body = fix_eols(body) 186. 187. # BAW: We're accumulating the body text by string concatenation. That 188. # can't be very efficient, but I don't have time now to rewrite it. It 189. # just feels like this algorithm could be more efficient. 190. encoded_body = '' 191. lineno = -1 192. # Preserve line endings here so we can check later to see an eol needs to 193. # be added to the output later. 194. lines = body.splitlines(1) 195. for line in lines: 196. # But strip off line-endings for processing this line. 197. if line.endswith(CRLF): 198. line = line[:-2] 199. elif line[-1] in CRLF: 200. line = line[:-1] 201. 202. lineno += 1 203. encoded_line = '' 204. prev = None 205. linelen = len(line) 206. # Now we need to examine every character to see if it needs to be 207. # quopri encoded. BAW: again, string concatenation is inefficient. 208. for j in range(linelen): 209. c = line[j] 210. prev = c 211. if bqre.match(c): 212. c = quote(c) 213. elif j+1 == linelen: 214. # Check for whitespace at end of line; special case 215. if c not in ' \t': 216. encoded_line += c 217. prev = c 218. continue 219. # Check to see to see if the line has reached its maximum length 220. if len(encoded_line) + len(c) >= maxlinelen: 221. encoded_body += encoded_line + '=' + eol 222. encoded_line = '' 223. encoded_line += c 224. # Now at end of line.. 225. if prev and prev in ' \t': 226. # Special case for whitespace at end of file 227. if lineno + 1 == len(lines): 228. prev = quote(prev) 229. if len(encoded_line) + len(prev) > maxlinelen: 230. encoded_body += encoded_line + '=' + eol + prev 231. else: 232. encoded_body += encoded_line + prev 233. # Just normal whitespace at end of line 234. else: 235. encoded_body += encoded_line + prev + '=' + eol 236. encoded_line = '' 237. # Now look at the line we just finished and it has a line ending, we 238. # need to add eol to the end of the line. 239. if lines[lineno].endswith(CRLF) or lines[lineno][-1] in CRLF: 240. encoded_body += encoded_line + eol 241. else: 242. encoded_body += encoded_line 243. encoded_line = '' 244. return encoded_body 245. 246. 247. # For convenience and backwards compatibility w/ standard base64 module 248. body_encode = encode 249. encodestring = encode 250. 251. 252. 253. # BAW: I'm not sure if the intent was for the signature of this function to be 254. # the same as base64MIME.decode() or not... 255. def decode(encoded, eol=NL): 256. """Decode a quoted-printable string. 257. 258. Lines are separated with eol, which defaults to \\n. 259. """ 260. if not encoded: 261. return encoded 262. # BAW: see comment in encode() above. Again, we're building up the 263. # decoded string with string concatenation, which could be done much more 264. # efficiently. 265. decoded = '' 266. 267. for line in encoded.splitlines(): 268. line = line.rstrip() 269. if not line: 270. decoded += eol 271. continue 272. 273. i = 0 274. n = len(line) 275. while i < n: 276. c = line[i] 277. if c <> '=': 278. decoded += c 279. i += 1 280. # Otherwise, c == "=". Are we at the end of the line? If so, add 281. # a soft line break. 282. elif i+1 == n: 283. i += 1 284. continue 285. # Decode if in form =AB 286. elif i+2 < n and line[i+1] in hexdigits and line[i+2] in hexdigits: 287. decoded += unquote(line[i:i+3]) 288. i += 3 289. # Otherwise, not in form =AB, pass literally 290. else: 291. decoded += c 292. i += 1 293. 294. if i == n: 295. decoded += eol 296. # Special case if original string did not end with eol 297. if not encoded.endswith(eol) and decoded.endswith(eol): 298. decoded = decoded[:-1] 299. return decoded 300. 301. 302. # For convenience and backwards compatibility w/ standard base64 module 303. body_decode = decode 304. decodestring = decode 305. 306. 307. 308. def _unquote_match(match): 309. """Turn a match in the form =AB to the ASCII character with value 0xab""" 310. s = match.group(0) 311. return unquote(s) 312. 313. 314. # Header decoding is done a bit differently 315. def header_decode(s): 316. """Decode a string encoded with RFC 2045 MIME header `Q' encoding. 317. 318. This function does not parse a full MIME header value encoded with 319. quoted-printable (like =?iso-8895-1?q?Hello_World?=) -- please use 320. the high level email.Header class for that functionality. 321. """ 322. s = s.replace('_', ' ') 323. return re.sub(r'=\w{2}', _unquote_match, s)