1 #!/usr/bin/env python 2 3 """ 4 Request helper classes. 5 6 Copyright (C) 2004, 2005, 2006, 2007, 2008 Paul Boddie <paul@boddie.org.uk> 7 8 This library is free software; you can redistribute it and/or 9 modify it under the terms of the GNU Lesser General Public 10 License as published by the Free Software Foundation; either 11 version 2.1 of the License, or (at your option) any later version. 12 13 This library is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 Lesser General Public License for more details. 17 18 You should have received a copy of the GNU Lesser General Public 19 License along with this library; if not, write to the Free Software 20 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA 21 """ 22 23 class MessageBodyStream: 24 25 """ 26 A naive stream class, providing a non-blocking stream for transactions when 27 reading the message body. According to the HTTP standard, the following 28 things decide how long the message is: 29 30 * Use of the Content-Length header field (see 4.4 Message Length). 31 * Use of the Transfer-Coding header field (see 3.6 Transfer Codings), 32 particularly when the "chunked" coding is used. 33 34 NOTE: For now, we don't support the Transfer-Coding business. 35 """ 36 37 def __init__(self, stream, headers): 38 39 """ 40 Initialise the object with the given underlying 'stream'. The supplied 41 'headers' in a dictionary-style object are used to examine the nature of 42 the request. 43 """ 44 45 self.stream = stream 46 self.headers = headers 47 self.length = int(headers.get("Content-Length") or 0) 48 49 def read(self, limit=None): 50 51 "Reads all remaining data from the message body." 52 53 if limit is not None: 54 limit = min(limit, self.length) 55 else: 56 limit = self.length 57 data = self.stream.read(limit) 58 self.length = self.length - len(data) 59 return data 60 61 def readline(self, n=None): 62 63 "Reads a single line of data from the message body." 64 65 data = [] 66 while self.length > 0: 67 data.append(self.read(1)) 68 if data[-1] == "\n": 69 break 70 return "".join(data) 71 72 def readlines(self): 73 74 """ 75 Reads all remaining data from the message body, splitting it into lines 76 and returning the data as a list of lines. 77 """ 78 79 lines = self.read().split("\n") 80 for i in range(0, len(lines) - 1): 81 lines[i] = lines[i] + "\n" 82 return lines 83 84 def close(self): 85 86 "Closes the stream." 87 88 self.stream.close() 89 90 class HeaderDict: 91 92 "A dictionary for headers." 93 94 def __init__(self, headers=None): 95 self.headers = {} 96 if headers is not None: 97 self.update(headers) 98 99 # Lower-case-string-coercing methods. 100 101 def __getitem__(self, key): 102 return self.headers[str(key).lower()] 103 104 def __setitem__(self, key, value): 105 self.headers[str(key).lower()] = value 106 107 def get(self, key, default=None): 108 return self.headers.get(str(key).lower(), default) 109 110 def has_key(self, key): 111 return self.headers.has_key(str(key).lower()) 112 113 # Forwarding methods. 114 115 def keys(self): 116 return self.headers.keys() 117 118 def values(self): 119 return self.headers.values() 120 121 def items(self): 122 return self.headers.items() 123 124 # Derived from the above. 125 126 def __contains__(self, key): 127 return self.has_key(key) 128 129 def update(self, other): 130 for k, v in other.items(): 131 self[k] = v 132 133 def __repr__(self): 134 return "HeaderDict(%r)" % self.headers 135 136 class HeaderValue: 137 138 "A container for header information." 139 140 def __init__(self, principal_value, **attributes): 141 142 """ 143 Initialise the container with the given 'principal_value' and optional 144 keyword attributes representing the key=value pairs which accompany the 145 'principal_value'. 146 """ 147 148 self.principal_value = principal_value 149 self.attributes = attributes 150 151 def __getattr__(self, name): 152 if self.attributes.has_key(name): 153 return self.attributes[name] 154 else: 155 raise AttributeError, name 156 157 def __repr__(self): 158 return "HeaderValue(%r)" % str(self) 159 160 def __str__(self): 161 162 """ 163 Format the header value object, producing a string suitable for the 164 response header field. 165 """ 166 167 l = [] 168 if self.principal_value: 169 l.append(self.principal_value) 170 for name, value in self.attributes.items(): 171 l.append("; ") 172 l.append("%s=%s" % (name, value)) 173 174 # Make sure that only ASCII is used. 175 176 return "".join(l).encode("US-ASCII") 177 178 class ContentType(HeaderValue): 179 180 "A container for content type information." 181 182 def __init__(self, media_type, charset=None, **attributes): 183 184 """ 185 Initialise the container with the given 'media_type', an optional 186 'charset', and optional keyword attributes representing the key=value 187 pairs which qualify content types. 188 """ 189 190 if charset is not None: 191 attributes["charset"] = charset 192 HeaderValue.__init__(self, media_type, **attributes) 193 194 def __getattr__(self, name): 195 if name == "media_type": 196 return self.principal_value 197 elif name == "charset": 198 return self.attributes.get("charset") 199 elif self.attributes.has_key(name): 200 return self.attributes[name] 201 else: 202 raise AttributeError, name 203 204 class Cookie: 205 206 """ 207 A simple cookie class for frameworks which do not return cookies in 208 structured form. Instances of this class contain the following attributes: 209 210 * name - the name associated with the cookie 211 * value - the value retained by the cookie 212 """ 213 214 def __init__(self, name, value): 215 self.name = name 216 self.value = value 217 218 class FileTooLargeError(Exception): 219 220 "An exception indicating that an uploaded file was too large." 221 222 pass 223 224 class FileContent: 225 226 """ 227 A simple class representing uploaded file content. This is useful in holding 228 metadata as well as being an indicator of such content in environments such 229 as Jython where it is not trivial to differentiate between plain strings and 230 Unicode in a fashion also applicable to CPython. 231 232 Instances of this class contain the following attributes: 233 234 * stream - a stream object through which the content of an uploaded file 235 may be accessed 236 * content - a plain string containing the contents of the uploaded file 237 * filename - a plain string containing the supplied filename of the 238 uploaded file 239 * headers - a dictionary containing the headers associated with the 240 uploaded file 241 * limit - a limit, if previously specified, on the size of uploaded 242 content 243 """ 244 245 def __init__(self, stream, headers=None, limit=None): 246 247 """ 248 Initialise the object with a 'stream' through which the file can be 249 read, along with optional 'headers' describing the content. An optional 250 'limit' can be specified to state the maximum number of bytes that may 251 be read before the content is considered too large. 252 """ 253 254 self.stream = stream 255 self.headers = headers or HeaderDict() 256 self.limit = limit 257 self.cache = None 258 259 def __getattr__(self, name): 260 261 """ 262 Provides a property value when 'name' is specified as "content" or as 263 "filename". 264 """ 265 266 if name == "content": 267 268 if self.cache is not None: 269 return self.cache 270 271 if self.reset(): 272 return self._read() 273 else: 274 self.cache = self._read() 275 return self.cache 276 277 elif name == "filename": 278 try: 279 content_disposition = self.headers["Content-Disposition"] 280 return content_disposition.filename 281 except (KeyError, AttributeError): 282 return None 283 284 else: 285 raise AttributeError, name 286 287 def _read(self): 288 289 """ 290 Read from the stream up to any limit, raising an exception if the 291 limit is exceeded. 292 """ 293 294 if self.limit is not None: 295 s = self.stream.read(self.limit) 296 if self.stream.read(1): 297 raise FileTooLargeError 298 else: 299 return s 300 else: 301 return self.stream.read() 302 303 def reset(self): 304 305 "Reset the stream providing the data, returning whether this succeeded." 306 307 # Python file objects. 308 309 if hasattr(self.stream, "seek"): 310 self.stream.seek(0) 311 return 1 312 313 # Java input streams. 314 315 elif hasattr(self.stream, "reset"): 316 self.stream.reset() 317 return 1 318 319 # Other streams. 320 321 else: 322 return 0 323 324 def __str__(self): 325 return self.content 326 327 def parse_header_value(header_class, header_value_str): 328 329 """ 330 Create an object of the given 'header_class' by determining the details 331 of the given 'header_value_str' - a string containing the value of a 332 particular header. 333 """ 334 335 if header_value_str is None: 336 return header_class(None) 337 338 l = header_value_str.split(";") 339 attributes = {} 340 341 # Find the attributes. 342 343 principal_value, attributes_str = l[0].strip(), l[1:] 344 345 for attribute_str in attributes_str: 346 t = attribute_str.split("=") 347 if len(t) > 1: 348 name, value = t[0].strip(), t[1].strip() 349 attributes[name] = value 350 351 return header_class(principal_value, **attributes) 352 353 def parse_headers(headers): 354 355 """ 356 Parse the given 'headers' dictionary (containing names mapped to values), 357 returing a dictionary mapping names to HeaderValue objects. 358 """ 359 360 new_headers = HeaderDict() 361 for name, value in headers.items(): 362 new_headers[name] = parse_header_value(HeaderValue, value) 363 return new_headers 364 365 def get_storage_items(storage_body): 366 367 """ 368 Return the items (2-tuples of the form key, values) from the 'storage_body'. 369 This is used in conjunction with FieldStorage objects. 370 """ 371 372 items = [] 373 for key in storage_body.keys(): 374 items.append((key, storage_body[key])) 375 return items 376 377 def get_body_fields(field_items, encoding): 378 379 """ 380 Returns a dictionary mapping field names to lists of field values for all 381 entries in the given 'field_items' (2-tuples of the form key, values) using 382 the given 'encoding'. 383 This is used in conjunction with FieldStorage objects. 384 """ 385 386 fields = {} 387 388 for field_name, field_values in field_items: 389 field_name = decode_value(field_name, encoding) 390 391 if type(field_values) == type([]): 392 fields[field_name] = [] 393 for field_value in field_values: 394 fields[field_name].append(get_body_field_or_file(field_value, encoding)) 395 else: 396 fields[field_name] = [get_body_field_or_file(field_values, encoding)] 397 398 return fields 399 400 def get_body_field_or_file(field_value, encoding): 401 402 """ 403 Returns the appropriate value for the given 'field_value' either for a 404 normal form field (thus employing the given 'encoding') or for a file 405 upload field (returning a plain string). 406 """ 407 408 if hasattr(field_value, "headers") and field_value.headers.has_key("content-type"): 409 410 # Detect stray FileUpload objects (eg. with Zope). 411 412 if hasattr(field_value, "read"): 413 return FileContent(field_value, parse_headers(field_value.headers)) 414 else: 415 return FileContent(field_value.file, parse_headers(field_value.headers)) 416 else: 417 return get_body_field(field_value, encoding) 418 419 def get_body_field(field_str, encoding): 420 421 """ 422 Returns the appropriate value for the given 'field_str' string using the 423 given 'encoding'. 424 """ 425 426 # Detect stray FieldStorage objects (eg. with Webware). 427 428 if hasattr(field_str, "value"): 429 return get_body_field(field_str.value, encoding) 430 else: 431 return decode_value(field_str, encoding) 432 433 def decode_value(s, encoding): 434 if encoding is not None: 435 try: 436 return unicode(s, encoding) 437 except UnicodeError: 438 pass 439 # NOTE: Hacks to permit graceful failure. 440 return unicode(s, "iso-8859-1") 441 442 def get_fields_from_query_string(query_string, decoder): 443 444 """ 445 Returns a dictionary mapping field names to lists of values for the data 446 encoded in the given 'query_string'. Use the given 'decoder' function or 447 method to process the URL-encoded values. 448 """ 449 450 fields = {} 451 452 for pair in query_string.split("&"): 453 t = pair.split("=") 454 name = decoder(t[0]) 455 456 if len(t) == 2: 457 value = decoder(t[1]) 458 else: 459 value = "" 460 461 # NOTE: Remove empty names. 462 463 if name: 464 if not fields.has_key(name): 465 fields[name] = [] 466 fields[name].append(value) 467 468 return fields 469 470 def filter_fields(all_fields, fields_from_path): 471 472 """ 473 Taking items from the 'all_fields' dictionary, produce a new dictionary 474 which does not contain items from the 'fields_from_path' dictionary. 475 Return a new dictionary. 476 """ 477 478 fields = {} 479 for field_name, field_values in all_fields.items(): 480 481 # Find the path values for this field (for filtering below). 482 483 if fields_from_path.has_key(field_name): 484 field_from_path_values = fields_from_path[field_name] 485 if type(field_from_path_values) != type([]): 486 field_from_path_values = [field_from_path_values] 487 else: 488 field_from_path_values = [] 489 490 fields[field_name] = [] 491 for field_value in field_values: 492 493 # Filter path values. 494 495 if field_value not in field_from_path_values: 496 fields[field_name].append(field_value) 497 498 # Remove filtered fields. 499 500 if fields[field_name] == []: 501 del fields[field_name] 502 503 return fields 504 505 # vim: tabstop=4 expandtab shiftwidth=4