You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
322 lines
11 KiB
322 lines
11 KiB
from __future__ import annotations
|
|
|
|
import re
|
|
import typing as t
|
|
from dataclasses import dataclass
|
|
from enum import auto
|
|
from enum import Enum
|
|
|
|
from ..datastructures import Headers
|
|
from ..exceptions import RequestEntityTooLarge
|
|
from ..http import parse_options_header
|
|
|
|
|
|
class Event:
|
|
pass
|
|
|
|
|
|
@dataclass(frozen=True)
|
|
class Preamble(Event):
|
|
data: bytes
|
|
|
|
|
|
@dataclass(frozen=True)
|
|
class Field(Event):
|
|
name: str
|
|
headers: Headers
|
|
|
|
|
|
@dataclass(frozen=True)
|
|
class File(Event):
|
|
name: str
|
|
filename: str
|
|
headers: Headers
|
|
|
|
|
|
@dataclass(frozen=True)
|
|
class Data(Event):
|
|
data: bytes
|
|
more_data: bool
|
|
|
|
|
|
@dataclass(frozen=True)
|
|
class Epilogue(Event):
|
|
data: bytes
|
|
|
|
|
|
class NeedData(Event):
|
|
pass
|
|
|
|
|
|
NEED_DATA = NeedData()
|
|
|
|
|
|
class State(Enum):
|
|
PREAMBLE = auto()
|
|
PART = auto()
|
|
DATA = auto()
|
|
DATA_START = auto()
|
|
EPILOGUE = auto()
|
|
COMPLETE = auto()
|
|
|
|
|
|
# Multipart line breaks MUST be CRLF (\r\n) by RFC-7578, except that
|
|
# many implementations break this and either use CR or LF alone.
|
|
LINE_BREAK = b"(?:\r\n|\n|\r)"
|
|
BLANK_LINE_RE = re.compile(b"(?:\r\n\r\n|\r\r|\n\n)", re.MULTILINE)
|
|
LINE_BREAK_RE = re.compile(LINE_BREAK, re.MULTILINE)
|
|
# Header values can be continued via a space or tab after the linebreak, as
|
|
# per RFC2231
|
|
HEADER_CONTINUATION_RE = re.compile(b"%s[ \t]" % LINE_BREAK, re.MULTILINE)
|
|
# This must be long enough to contain any line breaks plus any
|
|
# additional boundary markers (--) such that they will be found in a
|
|
# subsequent search
|
|
SEARCH_EXTRA_LENGTH = 8
|
|
|
|
|
|
class MultipartDecoder:
|
|
"""Decodes a multipart message as bytes into Python events.
|
|
|
|
The part data is returned as available to allow the caller to save
|
|
the data from memory to disk, if desired.
|
|
"""
|
|
|
|
def __init__(
|
|
self,
|
|
boundary: bytes,
|
|
max_form_memory_size: int | None = None,
|
|
*,
|
|
max_parts: int | None = None,
|
|
) -> None:
|
|
self.buffer = bytearray()
|
|
self.complete = False
|
|
self.max_form_memory_size = max_form_memory_size
|
|
self.max_parts = max_parts
|
|
self.state = State.PREAMBLE
|
|
self.boundary = boundary
|
|
|
|
# Note in the below \h i.e. horizontal whitespace is used
|
|
# as [^\S\n\r] as \h isn't supported in python.
|
|
|
|
# The preamble must end with a boundary where the boundary is
|
|
# prefixed by a line break, RFC2046. Except that many
|
|
# implementations including Werkzeug's tests omit the line
|
|
# break prefix. In addition the first boundary could be the
|
|
# epilogue boundary (for empty form-data) hence the matching
|
|
# group to understand if it is an epilogue boundary.
|
|
self.preamble_re = re.compile(
|
|
rb"%s?--%s(--[^\S\n\r]*%s?|[^\S\n\r]*%s)"
|
|
% (LINE_BREAK, re.escape(boundary), LINE_BREAK, LINE_BREAK),
|
|
re.MULTILINE,
|
|
)
|
|
# A boundary must include a line break prefix and suffix, and
|
|
# may include trailing whitespace. In addition the boundary
|
|
# could be the epilogue boundary hence the matching group to
|
|
# understand if it is an epilogue boundary.
|
|
self.boundary_re = re.compile(
|
|
rb"%s--%s(--[^\S\n\r]*%s?|[^\S\n\r]*%s)"
|
|
% (LINE_BREAK, re.escape(boundary), LINE_BREAK, LINE_BREAK),
|
|
re.MULTILINE,
|
|
)
|
|
self._search_position = 0
|
|
self._parts_decoded = 0
|
|
|
|
def last_newline(self, data: bytes) -> int:
|
|
try:
|
|
last_nl = data.rindex(b"\n")
|
|
except ValueError:
|
|
last_nl = len(data)
|
|
try:
|
|
last_cr = data.rindex(b"\r")
|
|
except ValueError:
|
|
last_cr = len(data)
|
|
|
|
return min(last_nl, last_cr)
|
|
|
|
def receive_data(self, data: bytes | None) -> None:
|
|
if data is None:
|
|
self.complete = True
|
|
elif (
|
|
self.max_form_memory_size is not None
|
|
and len(self.buffer) + len(data) > self.max_form_memory_size
|
|
):
|
|
raise RequestEntityTooLarge()
|
|
else:
|
|
self.buffer.extend(data)
|
|
|
|
def next_event(self) -> Event:
|
|
event: Event = NEED_DATA
|
|
|
|
if self.state == State.PREAMBLE:
|
|
match = self.preamble_re.search(self.buffer, self._search_position)
|
|
if match is not None:
|
|
if match.group(1).startswith(b"--"):
|
|
self.state = State.EPILOGUE
|
|
else:
|
|
self.state = State.PART
|
|
data = bytes(self.buffer[: match.start()])
|
|
del self.buffer[: match.end()]
|
|
event = Preamble(data=data)
|
|
self._search_position = 0
|
|
else:
|
|
# Update the search start position to be equal to the
|
|
# current buffer length (already searched) minus a
|
|
# safe buffer for part of the search target.
|
|
self._search_position = max(
|
|
0, len(self.buffer) - len(self.boundary) - SEARCH_EXTRA_LENGTH
|
|
)
|
|
|
|
elif self.state == State.PART:
|
|
match = BLANK_LINE_RE.search(self.buffer, self._search_position)
|
|
if match is not None:
|
|
headers = self._parse_headers(self.buffer[: match.start()])
|
|
# The final header ends with a single CRLF, however a
|
|
# blank line indicates the start of the
|
|
# body. Therefore the end is after the first CRLF.
|
|
headers_end = (match.start() + match.end()) // 2
|
|
del self.buffer[:headers_end]
|
|
|
|
if "content-disposition" not in headers:
|
|
raise ValueError("Missing Content-Disposition header")
|
|
|
|
disposition, extra = parse_options_header(
|
|
headers["content-disposition"]
|
|
)
|
|
name = t.cast(str, extra.get("name"))
|
|
filename = extra.get("filename")
|
|
if filename is not None:
|
|
event = File(
|
|
filename=filename,
|
|
headers=headers,
|
|
name=name,
|
|
)
|
|
else:
|
|
event = Field(
|
|
headers=headers,
|
|
name=name,
|
|
)
|
|
self.state = State.DATA_START
|
|
self._search_position = 0
|
|
self._parts_decoded += 1
|
|
|
|
if self.max_parts is not None and self._parts_decoded > self.max_parts:
|
|
raise RequestEntityTooLarge()
|
|
else:
|
|
# Update the search start position to be equal to the
|
|
# current buffer length (already searched) minus a
|
|
# safe buffer for part of the search target.
|
|
self._search_position = max(0, len(self.buffer) - SEARCH_EXTRA_LENGTH)
|
|
|
|
elif self.state == State.DATA_START:
|
|
data, del_index, more_data = self._parse_data(self.buffer, start=True)
|
|
del self.buffer[:del_index]
|
|
event = Data(data=data, more_data=more_data)
|
|
if more_data:
|
|
self.state = State.DATA
|
|
|
|
elif self.state == State.DATA:
|
|
data, del_index, more_data = self._parse_data(self.buffer, start=False)
|
|
del self.buffer[:del_index]
|
|
if data or not more_data:
|
|
event = Data(data=data, more_data=more_data)
|
|
|
|
elif self.state == State.EPILOGUE and self.complete:
|
|
event = Epilogue(data=bytes(self.buffer))
|
|
del self.buffer[:]
|
|
self.state = State.COMPLETE
|
|
|
|
if self.complete and isinstance(event, NeedData):
|
|
raise ValueError(f"Invalid form-data cannot parse beyond {self.state}")
|
|
|
|
return event
|
|
|
|
def _parse_headers(self, data: bytes) -> Headers:
|
|
headers: list[tuple[str, str]] = []
|
|
# Merge the continued headers into one line
|
|
data = HEADER_CONTINUATION_RE.sub(b" ", data)
|
|
# Now there is one header per line
|
|
for line in data.splitlines():
|
|
line = line.strip()
|
|
|
|
if line != b"":
|
|
name, _, value = line.decode().partition(":")
|
|
headers.append((name.strip(), value.strip()))
|
|
return Headers(headers)
|
|
|
|
def _parse_data(self, data: bytes, *, start: bool) -> tuple[bytes, int, bool]:
|
|
# Body parts must start with CRLF (or CR or LF)
|
|
if start:
|
|
match = LINE_BREAK_RE.match(data)
|
|
data_start = t.cast(t.Match[bytes], match).end()
|
|
else:
|
|
data_start = 0
|
|
|
|
boundary = b"--" + self.boundary
|
|
|
|
if self.buffer.find(boundary) == -1:
|
|
# No complete boundary in the buffer, but there may be
|
|
# a partial boundary at the end. As the boundary
|
|
# starts with either a nl or cr find the earliest and
|
|
# return up to that as data.
|
|
data_end = del_index = self.last_newline(data[data_start:]) + data_start
|
|
# If amount of data after last newline is far from
|
|
# possible length of partial boundary, we should
|
|
# assume that there is no partial boundary in the buffer
|
|
# and return all pending data.
|
|
if (len(data) - data_end) > len(b"\n" + boundary):
|
|
data_end = del_index = len(data)
|
|
more_data = True
|
|
else:
|
|
match = self.boundary_re.search(data)
|
|
if match is not None:
|
|
if match.group(1).startswith(b"--"):
|
|
self.state = State.EPILOGUE
|
|
else:
|
|
self.state = State.PART
|
|
data_end = match.start()
|
|
del_index = match.end()
|
|
else:
|
|
data_end = del_index = self.last_newline(data[data_start:]) + data_start
|
|
more_data = match is None
|
|
|
|
return bytes(data[data_start:data_end]), del_index, more_data
|
|
|
|
|
|
class MultipartEncoder:
|
|
def __init__(self, boundary: bytes) -> None:
|
|
self.boundary = boundary
|
|
self.state = State.PREAMBLE
|
|
|
|
def send_event(self, event: Event) -> bytes:
|
|
if isinstance(event, Preamble) and self.state == State.PREAMBLE:
|
|
self.state = State.PART
|
|
return event.data
|
|
elif isinstance(event, (Field, File)) and self.state in {
|
|
State.PREAMBLE,
|
|
State.PART,
|
|
State.DATA,
|
|
}:
|
|
data = b"\r\n--" + self.boundary + b"\r\n"
|
|
data += b'Content-Disposition: form-data; name="%s"' % event.name.encode()
|
|
if isinstance(event, File):
|
|
data += b'; filename="%s"' % event.filename.encode()
|
|
data += b"\r\n"
|
|
for name, value in t.cast(Field, event).headers:
|
|
if name.lower() != "content-disposition":
|
|
data += f"{name}: {value}\r\n".encode()
|
|
self.state = State.DATA_START
|
|
return data
|
|
elif isinstance(event, Data) and self.state == State.DATA_START:
|
|
self.state = State.DATA
|
|
if len(event.data) > 0:
|
|
return b"\r\n" + event.data
|
|
else:
|
|
return event.data
|
|
elif isinstance(event, Data) and self.state == State.DATA:
|
|
return event.data
|
|
elif isinstance(event, Epilogue):
|
|
self.state = State.COMPLETE
|
|
return b"\r\n--" + self.boundary + b"--\r\n" + event.data
|
|
else:
|
|
raise ValueError(f"Cannot generate {event} in state: {self.state}")
|