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|
"""
Handlers for Content-Encoding.
See: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding
"""
from __future__ import annotations
import codecs
import io
import typing
import zlib
from ._compat import brotli
from ._exceptions import DecodingError
class ContentDecoder:
def decode(self, data: bytes) -> bytes:
raise NotImplementedError() # pragma: no cover
def flush(self) -> bytes:
raise NotImplementedError() # pragma: no cover
class IdentityDecoder(ContentDecoder):
"""
Handle unencoded data.
"""
def decode(self, data: bytes) -> bytes:
return data
def flush(self) -> bytes:
return b""
class DeflateDecoder(ContentDecoder):
"""
Handle 'deflate' decoding.
See: https://stackoverflow.com/questions/1838699
"""
def __init__(self) -> None:
self.first_attempt = True
self.decompressor = zlib.decompressobj()
def decode(self, data: bytes) -> bytes:
was_first_attempt = self.first_attempt
self.first_attempt = False
try:
return self.decompressor.decompress(data)
except zlib.error as exc:
if was_first_attempt:
self.decompressor = zlib.decompressobj(-zlib.MAX_WBITS)
return self.decode(data)
raise DecodingError(str(exc)) from exc
def flush(self) -> bytes:
try:
return self.decompressor.flush()
except zlib.error as exc: # pragma: no cover
raise DecodingError(str(exc)) from exc
class GZipDecoder(ContentDecoder):
"""
Handle 'gzip' decoding.
See: https://stackoverflow.com/questions/1838699
"""
def __init__(self) -> None:
self.decompressor = zlib.decompressobj(zlib.MAX_WBITS | 16)
def decode(self, data: bytes) -> bytes:
try:
return self.decompressor.decompress(data)
except zlib.error as exc:
raise DecodingError(str(exc)) from exc
def flush(self) -> bytes:
try:
return self.decompressor.flush()
except zlib.error as exc: # pragma: no cover
raise DecodingError(str(exc)) from exc
class BrotliDecoder(ContentDecoder):
"""
Handle 'brotli' decoding.
Requires `pip install brotlipy`. See: https://brotlipy.readthedocs.io/
or `pip install brotli`. See https://github.com/google/brotli
Supports both 'brotlipy' and 'Brotli' packages since they share an import
name. The top branches are for 'brotlipy' and bottom branches for 'Brotli'
"""
def __init__(self) -> None:
if brotli is None: # pragma: no cover
raise ImportError(
"Using 'BrotliDecoder', but neither of the 'brotlicffi' or 'brotli' "
"packages have been installed. "
"Make sure to install httpx using `pip install httpx[brotli]`."
) from None
self.decompressor = brotli.Decompressor()
self.seen_data = False
self._decompress: typing.Callable[[bytes], bytes]
if hasattr(self.decompressor, "decompress"):
# The 'brotlicffi' package.
self._decompress = self.decompressor.decompress # pragma: no cover
else:
# The 'brotli' package.
self._decompress = self.decompressor.process # pragma: no cover
def decode(self, data: bytes) -> bytes:
if not data:
return b""
self.seen_data = True
try:
return self._decompress(data)
except brotli.error as exc:
raise DecodingError(str(exc)) from exc
def flush(self) -> bytes:
if not self.seen_data:
return b""
try:
if hasattr(self.decompressor, "finish"):
# Only available in the 'brotlicffi' package.
# As the decompressor decompresses eagerly, this
# will never actually emit any data. However, it will potentially throw
# errors if a truncated or damaged data stream has been used.
self.decompressor.finish() # pragma: no cover
return b""
except brotli.error as exc: # pragma: no cover
raise DecodingError(str(exc)) from exc
class MultiDecoder(ContentDecoder):
"""
Handle the case where multiple encodings have been applied.
"""
def __init__(self, children: typing.Sequence[ContentDecoder]) -> None:
"""
'children' should be a sequence of decoders in the order in which
each was applied.
"""
# Note that we reverse the order for decoding.
self.children = list(reversed(children))
def decode(self, data: bytes) -> bytes:
for child in self.children:
data = child.decode(data)
return data
def flush(self) -> bytes:
data = b""
for child in self.children:
data = child.decode(data) + child.flush()
return data
class ByteChunker:
"""
Handles returning byte content in fixed-size chunks.
"""
def __init__(self, chunk_size: int | None = None) -> None:
self._buffer = io.BytesIO()
self._chunk_size = chunk_size
def decode(self, content: bytes) -> list[bytes]:
if self._chunk_size is None:
return [content] if content else []
self._buffer.write(content)
if self._buffer.tell() >= self._chunk_size:
value = self._buffer.getvalue()
chunks = [
value[i : i + self._chunk_size]
for i in range(0, len(value), self._chunk_size)
]
if len(chunks[-1]) == self._chunk_size:
self._buffer.seek(0)
self._buffer.truncate()
return chunks
else:
self._buffer.seek(0)
self._buffer.write(chunks[-1])
self._buffer.truncate()
return chunks[:-1]
else:
return []
def flush(self) -> list[bytes]:
value = self._buffer.getvalue()
self._buffer.seek(0)
self._buffer.truncate()
return [value] if value else []
class TextChunker:
"""
Handles returning text content in fixed-size chunks.
"""
def __init__(self, chunk_size: int | None = None) -> None:
self._buffer = io.StringIO()
self._chunk_size = chunk_size
def decode(self, content: str) -> list[str]:
if self._chunk_size is None:
return [content] if content else []
self._buffer.write(content)
if self._buffer.tell() >= self._chunk_size:
value = self._buffer.getvalue()
chunks = [
value[i : i + self._chunk_size]
for i in range(0, len(value), self._chunk_size)
]
if len(chunks[-1]) == self._chunk_size:
self._buffer.seek(0)
self._buffer.truncate()
return chunks
else:
self._buffer.seek(0)
self._buffer.write(chunks[-1])
self._buffer.truncate()
return chunks[:-1]
else:
return []
def flush(self) -> list[str]:
value = self._buffer.getvalue()
self._buffer.seek(0)
self._buffer.truncate()
return [value] if value else []
class TextDecoder:
"""
Handles incrementally decoding bytes into text
"""
def __init__(self, encoding: str = "utf-8") -> None:
self.decoder = codecs.getincrementaldecoder(encoding)(errors="replace")
def decode(self, data: bytes) -> str:
return self.decoder.decode(data)
def flush(self) -> str:
return self.decoder.decode(b"", True)
class LineDecoder:
"""
Handles incrementally reading lines from text.
Has the same behaviour as the stdllib splitlines,
but handling the input iteratively.
"""
def __init__(self) -> None:
self.buffer: list[str] = []
self.trailing_cr: bool = False
def decode(self, text: str) -> list[str]:
# See https://docs.python.org/3/library/stdtypes.html#str.splitlines
NEWLINE_CHARS = "\n\r\x0b\x0c\x1c\x1d\x1e\x85\u2028\u2029"
# We always push a trailing `\r` into the next decode iteration.
if self.trailing_cr:
text = "\r" + text
self.trailing_cr = False
if text.endswith("\r"):
self.trailing_cr = True
text = text[:-1]
if not text:
# NOTE: the edge case input of empty text doesn't occur in practice,
# because other httpx internals filter out this value
return [] # pragma: no cover
trailing_newline = text[-1] in NEWLINE_CHARS
lines = text.splitlines()
if len(lines) == 1 and not trailing_newline:
# No new lines, buffer the input and continue.
self.buffer.append(lines[0])
return []
if self.buffer:
# Include any existing buffer in the first portion of the
# splitlines result.
lines = ["".join(self.buffer) + lines[0]] + lines[1:]
self.buffer = []
if not trailing_newline:
# If the last segment of splitlines is not newline terminated,
# then drop it from our output and start a new buffer.
self.buffer = [lines.pop()]
return lines
def flush(self) -> list[str]:
if not self.buffer and not self.trailing_cr:
return []
lines = ["".join(self.buffer)]
self.buffer = []
self.trailing_cr = False
return lines
SUPPORTED_DECODERS = {
"identity": IdentityDecoder,
"gzip": GZipDecoder,
"deflate": DeflateDecoder,
"br": BrotliDecoder,
}
if brotli is None:
SUPPORTED_DECODERS.pop("br") # pragma: no cover
|
