From RFC7231: If one or more encodings have been applied to a representation, the sender that applied the encodings MUST generate a Content-Encoding header field that lists the content codings in the order in which they were applied.
| 298 | |
| 299 | |
| 300 | class MultiDecoder(ContentDecoder): |
| 301 | """ |
| 302 | From RFC7231: |
| 303 | If one or more encodings have been applied to a representation, the |
| 304 | sender that applied the encodings MUST generate a Content-Encoding |
| 305 | header field that lists the content codings in the order in which |
| 306 | they were applied. |
| 307 | """ |
| 308 | |
| 309 | # Maximum allowed number of chained HTTP encodings in the |
| 310 | # Content-Encoding header. |
| 311 | max_decode_links = 5 |
| 312 | |
| 313 | def __init__(self, modes: str) -> None: |
| 314 | encodings = [m.strip() for m in modes.split(",")] |
| 315 | if len(encodings) > self.max_decode_links: |
| 316 | raise DecodeError( |
| 317 | "Too many content encodings in the chain: " |
| 318 | f"{len(encodings)} > {self.max_decode_links}" |
| 319 | ) |
| 320 | self._decoders = [_get_decoder(e) for e in encodings] |
| 321 | |
| 322 | def flush(self) -> bytes: |
| 323 | return self._decoders[0].flush() |
| 324 | |
| 325 | def decompress(self, data: bytes, max_length: int = -1) -> bytes: |
| 326 | if max_length <= 0: |
| 327 | for d in reversed(self._decoders): |
| 328 | data = d.decompress(data) |
| 329 | return data |
| 330 | |
| 331 | ret = bytearray() |
| 332 | # Every while loop iteration goes through all decoders once. |
| 333 | # It exits when enough data is read or no more data can be read. |
| 334 | # It is possible that the while loop iteration does not produce |
| 335 | # any data because we retrieve up to `max_length` from every |
| 336 | # decoder, and the amount of bytes may be insufficient for the |
| 337 | # next decoder to produce enough/any output. |
| 338 | while True: |
| 339 | any_data = False |
| 340 | for d in reversed(self._decoders): |
| 341 | data = d.decompress(data, max_length=max_length - len(ret)) |
| 342 | if data: |
| 343 | any_data = True |
| 344 | # We should not break when no data is returned because |
| 345 | # next decoders may produce data even with empty input. |
| 346 | ret += data |
| 347 | if not any_data or len(ret) >= max_length: |
| 348 | return bytes(ret) |
| 349 | data = b"" |
| 350 | |
| 351 | @property |
| 352 | def has_unconsumed_tail(self) -> bool: |
| 353 | return any(d.has_unconsumed_tail for d in self._decoders) |
| 354 | |
| 355 | |
| 356 | def _get_decoder(mode: str) -> ContentDecoder: |