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http_parser.py
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import abc import asyncio import collections import re import string import zlib from contextlib import suppress from enum import IntEnum from typing import ( Any, Generic, List, NamedTuple, Optional, Pattern, Set, Tuple, Type, TypeVar, Union, cast, ) from multidict import CIMultiDict, CIMultiDictProxy, istr from yarl import URL from . import hdrs from .base_protocol import BaseProtocol from .helpers import NO_EXTENSIONS, BaseTimerContext from .http_exceptions import ( BadHttpMessage, BadStatusLine, ContentEncodingError, ContentLengthError, InvalidHeader, LineTooLong, TransferEncodingError, ) from .http_writer import HttpVersion, HttpVersion10 from .log import internal_logger from .streams import EMPTY_PAYLOAD, StreamReader from .typedefs import Final, RawHeaders try: import brotli HAS_BROTLI = True except ImportError: # pragma: no cover HAS_BROTLI = False __all__ = ( "HeadersParser", "HttpParser", "HttpRequestParser", "HttpResponseParser", "RawRequestMessage", "RawResponseMessage", ) ASCIISET: Final[Set[str]] = set(string.printable) # See https://tools.ietf.org/html/rfc7230#section-3.1.1 # and https://tools.ietf.org/html/rfc7230#appendix-B # # method = token # tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." / # "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA # token = 1*tchar METHRE: Final[Pattern[str]] = re.compile(r"[!#$%&'*+\-.^_`|~0-9A-Za-z]+") VERSRE: Final[Pattern[str]] = re.compile(r"HTTP/(\d+).(\d+)") HDRRE: Final[Pattern[bytes]] = re.compile(rb"[\x00-\x1F\x7F()<>@,;:\[\]={} \t\\\\\"]") class RawRequestMessage(NamedTuple): method: str path: str version: HttpVersion headers: "CIMultiDictProxy[str]" raw_headers: RawHeaders should_close: bool compression: Optional[str] upgrade: bool chunked: bool url: URL RawResponseMessage = collections.namedtuple( "RawResponseMessage", [ "version", "code", "reason", "headers", "raw_headers", "should_close", "compression", "upgrade", "chunked", ], ) _MsgT = TypeVar("_MsgT", RawRequestMessage, RawResponseMessage) class ParseState(IntEnum): PARSE_NONE = 0 PARSE_LENGTH = 1 PARSE_CHUNKED = 2 PARSE_UNTIL_EOF = 3 class ChunkState(IntEnum): PARSE_CHUNKED_SIZE = 0 PARSE_CHUNKED_CHUNK = 1 PARSE_CHUNKED_CHUNK_EOF = 2 PARSE_MAYBE_TRAILERS = 3 PARSE_TRAILERS = 4 class HeadersParser: def __init__( self, max_line_size: int = 8190, max_headers: int = 32768, max_field_size: int = 8190, ) -> None: self.max_line_size = max_line_size self.max_headers = max_headers self.max_field_size = max_field_size def parse_headers( self, lines: List[bytes] ) -> Tuple["CIMultiDictProxy[str]", RawHeaders]: headers = CIMultiDict() # type: CIMultiDict[str] raw_headers = [] lines_idx = 1 line = lines[1] line_count = len(lines) while line: # Parse initial header name : value pair. try: bname, bvalue = line.split(b":", 1) except ValueError: raise InvalidHeader(line) from None bname = bname.strip(b" \t") bvalue = bvalue.lstrip() if HDRRE.search(bname): raise InvalidHeader(bname) if len(bname) > self.max_field_size: raise LineTooLong( "request header name {}".format( bname.decode("utf8", "xmlcharrefreplace") ), str(self.max_field_size), str(len(bname)), ) header_length = len(bvalue) # next line lines_idx += 1 line = lines[lines_idx] # consume continuation lines continuation = line and line[0] in (32, 9) # (' ', '\t') if continuation: bvalue_lst = [bvalue] while continuation: header_length += len(line) if header_length > self.max_field_size: raise LineTooLong( "request header field {}".format( bname.decode("utf8", "xmlcharrefreplace") ), str(self.max_field_size), str(header_length), ) bvalue_lst.append(line) # next line lines_idx += 1 if lines_idx < line_count: line = lines[lines_idx] if line: continuation = line[0] in (32, 9) # (' ', '\t') else: line = b"" break bvalue = b"".join(bvalue_lst) else: if header_length > self.max_field_size: raise LineTooLong( "request header field {}".format( bname.decode("utf8", "xmlcharrefreplace") ), str(self.max_field_size), str(header_length), ) bvalue = bvalue.strip() name = bname.decode("utf-8", "surrogateescape") value = bvalue.decode("utf-8", "surrogateescape") headers.add(name, value) raw_headers.append((bname, bvalue)) return (CIMultiDictProxy(headers), tuple(raw_headers)) class HttpParser(abc.ABC, Generic[_MsgT]): def __init__( self, protocol: Optional[BaseProtocol] = None, loop: Optional[asyncio.AbstractEventLoop] = None, limit: int = 2 ** 16, max_line_size: int = 8190, max_headers: int = 32768, max_field_size: int = 8190, timer: Optional[BaseTimerContext] = None, code: Optional[int] = None, method: Optional[str] = None, readall: bool = False, payload_exception: Optional[Type[BaseException]] = None, response_with_body: bool = True, read_until_eof: bool = False, auto_decompress: bool = True, ) -> None: self.protocol = protocol self.loop = loop self.max_line_size = max_line_size self.max_headers = max_headers self.max_field_size = max_field_size self.timer = timer self.code = code self.method = method self.readall = readall self.payload_exception = payload_exception self.response_with_body = response_with_body self.read_until_eof = read_until_eof self._lines = [] # type: List[bytes] self._tail = b"" self._upgraded = False self._payload = None self._payload_parser = None # type: Optional[HttpPayloadParser] self._auto_decompress = auto_decompress self._limit = limit self._headers_parser = HeadersParser(max_line_size, max_headers, max_field_size) @abc.abstractmethod def parse_message(self, lines: List[bytes]) -> _MsgT: pass def feed_eof(self) -> Optional[_MsgT]: if self._payload_parser is not None: self._payload_parser.feed_eof() self._payload_parser = None else: # try to extract partial message if self._tail: self._lines.append(self._tail) if self._lines: if self._lines[-1] != "\r\n": self._lines.append(b"") with suppress(Exception): return self.parse_message(self._lines) return None def feed_data( self, data: bytes, SEP: bytes = b"\r\n", EMPTY: bytes = b"", CONTENT_LENGTH: istr = hdrs.CONTENT_LENGTH, METH_CONNECT: str = hdrs.METH_CONNECT, SEC_WEBSOCKET_KEY1: istr = hdrs.SEC_WEBSOCKET_KEY1, ) -> Tuple[List[Tuple[_MsgT, StreamReader]], bool, bytes]: messages = [] if self._tail: data, self._tail = self._tail + data, b"" data_len = len(data) start_pos = 0 loop = self.loop while start_pos < data_len: # read HTTP message (request/response line + headers), \r\n\r\n # and split by lines if self._payload_parser is None and not self._upgraded: pos = data.find(SEP, start_pos) # consume \r\n if pos == start_pos and not self._lines: start_pos = pos + 2 continue if pos >= start_pos: # line found self._lines.append(data[start_pos:pos]) start_pos = pos + 2 # \r\n\r\n found if self._lines[-1] == EMPTY: try: msg: _MsgT = self.parse_message(self._lines) finally: self._lines.clear() def get_content_length() -> Optional[int]: # payload length length_hdr = msg.headers.get(CONTENT_LENGTH) if length_hdr is None: return None try: length = int(length_hdr) except ValueError: raise InvalidHeader(CONTENT_LENGTH) if length < 0: raise InvalidHeader(CONTENT_LENGTH) return length length = get_content_length() # do not support old websocket spec if SEC_WEBSOCKET_KEY1 in msg.headers: raise InvalidHeader(SEC_WEBSOCKET_KEY1) self._upgraded = msg.upgrade method = getattr(msg, "method", self.method) assert self.protocol is not None # calculate payload if ( (length is not None and length > 0) or msg.chunked and not msg.upgrade ): payload = StreamReader( self.protocol, timer=self.timer, loop=loop, limit=self._limit, ) payload_parser = HttpPayloadParser( payload, length=length, chunked=msg.chunked, method=method, compression=msg.compression, code=self.code, readall=self.readall, response_with_body=self.response_with_body, auto_decompress=self._auto_decompress, ) if not payload_parser.done: self._payload_parser = payload_parser elif method == METH_CONNECT: assert isinstance(msg, RawRequestMessage) payload = StreamReader( self.protocol, timer=self.timer, loop=loop, limit=self._limit, ) self._upgraded = True self._payload_parser = HttpPayloadParser( payload, method=msg.method, compression=msg.compression, readall=True, auto_decompress=self._auto_decompress, ) else: if ( getattr(msg, "code", 100) >= 199 and length is None and self.read_until_eof ): payload = StreamReader( self.protocol, timer=self.timer, loop=loop, limit=self._limit, ) payload_parser = HttpPayloadParser( payload, length=length, chunked=msg.chunked, method=method, compression=msg.compression, code=self.code, readall=True, response_with_body=self.response_with_body, auto_decompress=self._auto_decompress, ) if not payload_parser.done: self._payload_parser = payload_parser else: payload = EMPTY_PAYLOAD messages.append((msg, payload)) else: self._tail = data[start_pos:] data = EMPTY break # no parser, just store elif self._payload_parser is None and self._upgraded: assert not self._lines break # feed payload elif data and start_pos < data_len: assert not self._lines assert self._payload_parser is not None try: eof, data = self._payload_parser.feed_data(data[start_pos:]) except BaseException as exc: if self.payload_exception is not None: self._payload_parser.payload.set_exception( self.payload_exception(str(exc)) ) else: self._payload_parser.payload.set_exception(exc) eof = True data = b"" if eof: start_pos = 0 data_len = len(data) self._payload_parser = None continue else: break if data and start_pos < data_len: data = data[start_pos:] else: data = EMPTY return messages, self._upgraded, data def parse_headers( self, lines: List[bytes] ) -> Tuple[ "CIMultiDictProxy[str]", RawHeaders, Optional[bool], Optional[str], bool, bool ]: """Parses RFC 5322 headers from a stream. Line continuations are supported. Returns list of header name and value pairs. Header name is in upper case. """ headers, raw_headers = self._headers_parser.parse_headers(lines) close_conn = None encoding = None upgrade = False chunked = False # keep-alive conn = headers.get(hdrs.CONNECTION) if conn: v = conn.lower() if v == "close": close_conn = True elif v == "keep-alive": close_conn = False elif v == "upgrade": upgrade = True # encoding enc = headers.get(hdrs.CONTENT_ENCODING) if enc: enc = enc.lower() if enc in ("gzip", "deflate", "br"): encoding = enc # chunking te = headers.get(hdrs.TRANSFER_ENCODING) if te is not None: if "chunked" == te.lower(): chunked = True else: raise BadHttpMessage("Request has invalid `Transfer-Encoding`") if hdrs.CONTENT_LENGTH in headers: raise BadHttpMessage( "Content-Length can't be present with Transfer-Encoding", ) return (headers, raw_headers, close_conn, encoding, upgrade, chunked) def set_upgraded(self, val: bool) -> None: """Set connection upgraded (to websocket) mode. :param bool val: new state. """ self._upgraded = val class HttpRequestParser(HttpParser[RawRequestMessage]): """Read request status line. Exception .http_exceptions.BadStatusLine could be raised in case of any errors in status line. Returns RawRequestMessage. """ def parse_message(self, lines: List[bytes]) -> RawRequestMessage: # request line line = lines[0].decode("utf-8", "surrogateescape") try: method, path, version = line.split(None, 2) except ValueError: raise BadStatusLine(line) from None if len(path) > self.max_line_size: raise LineTooLong( "Status line is too long", str(self.max_line_size), str(len(path)) ) path_part, _hash_separator, url_fragment = path.partition("#") path_part, _question_mark_separator, qs_part = path_part.partition("?") # method if not METHRE.match(method): raise BadStatusLine(method) # version try: if version.startswith("HTTP/"): n1, n2 = version[5:].split(".", 1) version_o = HttpVersion(int(n1), int(n2)) else: raise BadStatusLine(version) except Exception: raise BadStatusLine(version) # read headers ( headers, raw_headers, close, compression, upgrade, chunked, ) = self.parse_headers(lines) if close is None: # then the headers weren't set in the request if version_o <= HttpVersion10: # HTTP 1.0 must asks to not close close = True else: # HTTP 1.1 must ask to close. close = False return RawRequestMessage( method, path, version_o, headers, raw_headers, close, compression, upgrade, chunked, # NOTE: `yarl.URL.build()` is used to mimic what the Cython-based # NOTE: parser does, otherwise it results into the same # NOTE: HTTP Request-Line input producing different # NOTE: `yarl.URL()` objects URL.build( path=path_part, query_string=qs_part, fragment=url_fragment, encoded=True, ), ) class HttpResponseParser(HttpParser[RawResponseMessage]): """Read response status line and headers. BadStatusLine could be raised in case of any errors in status line. Returns RawResponseMessage. """ def parse_message(self, lines: List[bytes]) -> RawResponseMessage: line = lines[0].decode("utf-8", "surrogateescape") try: version, status = line.split(None, 1) except ValueError: raise BadStatusLine(line) from None try: status, reason = status.split(None, 1) except ValueError: reason = "" if len(reason) > self.max_line_size: raise LineTooLong( "Status line is too long", str(self.max_line_size), str(len(reason)) ) # version match = VERSRE.match(version) if match is None: raise BadStatusLine(line) version_o = HttpVersion(int(match.group(1)), int(match.group(2))) # The status code is a three-digit number try: status_i = int(status) except ValueError: raise BadStatusLine(line) from None if status_i > 999: raise BadStatusLine(line) # read headers ( headers, raw_headers, close, compression, upgrade, chunked, ) = self.parse_headers(lines) if close is None: close = version_o <= HttpVersion10 return RawResponseMessage( version_o, status_i, reason.strip(), headers, raw_headers, close, compression, upgrade, chunked, ) class HttpPayloadParser: def __init__( self, payload: StreamReader, length: Optional[int] = None, chunked: bool = False, compression: Optional[str] = None, code: Optional[int] = None, method: Optional[str] = None, readall: bool = False, response_with_body: bool = True, auto_decompress: bool = True, ) -> None: self._length = 0 self._type = ParseState.PARSE_NONE self._chunk = ChunkState.PARSE_CHUNKED_SIZE self._chunk_size = 0 self._chunk_tail = b"" self._auto_decompress = auto_decompress self.done = False # payload decompression wrapper if response_with_body and compression and self._auto_decompress: real_payload = DeflateBuffer( payload, compression ) # type: Union[StreamReader, DeflateBuffer] else: real_payload = payload # payload parser if not response_with_body: # don't parse payload if it's not expected to be received self._type = ParseState.PARSE_NONE real_payload.feed_eof() self.done = True elif chunked: self._type = ParseState.PARSE_CHUNKED elif length is not None: self._type = ParseState.PARSE_LENGTH self._length = length if self._length == 0: real_payload.feed_eof() self.done = True else: if readall and code != 204: self._type = ParseState.PARSE_UNTIL_EOF elif method in ("PUT", "POST"): internal_logger.warning( # pragma: no cover "Content-Length or Transfer-Encoding header is required" ) self._type = ParseState.PARSE_NONE real_payload.feed_eof() self.done = True self.payload = real_payload def feed_eof(self) -> None: if self._type == ParseState.PARSE_UNTIL_EOF: self.payload.feed_eof() elif self._type == ParseState.PARSE_LENGTH: raise ContentLengthError( "Not enough data for satisfy content length header." ) elif self._type == ParseState.PARSE_CHUNKED: raise TransferEncodingError( "Not enough data for satisfy transfer length header." ) def feed_data( self, chunk: bytes, SEP: bytes = b"\r\n", CHUNK_EXT: bytes = b";" ) -> Tuple[bool, bytes]: # Read specified amount of bytes if self._type == ParseState.PARSE_LENGTH: required = self._length chunk_len = len(chunk) if required >= chunk_len: self._length = required - chunk_len self.payload.feed_data(chunk, chunk_len) if self._length == 0: self.payload.feed_eof() return True, b"" else: self._length = 0 self.payload.feed_data(chunk[:required], required) self.payload.feed_eof() return True, chunk[required:] # Chunked transfer encoding parser elif self._type == ParseState.PARSE_CHUNKED: if self._chunk_tail: chunk = self._chunk_tail + chunk self._chunk_tail = b"" while chunk: # read next chunk size if self._chunk == ChunkState.PARSE_CHUNKED_SIZE: pos = chunk.find(SEP) if pos >= 0: i = chunk.find(CHUNK_EXT, 0, pos) if i >= 0: size_b = chunk[:i] # strip chunk-extensions else: size_b = chunk[:pos] try: size = int(bytes(size_b), 16) except ValueError: exc = TransferEncodingError( chunk[:pos].decode("ascii", "surrogateescape") ) self.payload.set_exception(exc) raise exc from None chunk = chunk[pos + 2 :] if size == 0: # eof marker self._chunk = ChunkState.PARSE_MAYBE_TRAILERS else: self._chunk = ChunkState.PARSE_CHUNKED_CHUNK self._chunk_size = size self.payload.begin_http_chunk_receiving() else: self._chunk_tail = chunk return False, b"" # read chunk and feed buffer if self._chunk == ChunkState.PARSE_CHUNKED_CHUNK: required = self._chunk_size chunk_len = len(chunk) if required > chunk_len: self._chunk_size = required - chunk_len self.payload.feed_data(chunk, chunk_len) return False, b"" else: self._chunk_size = 0 self.payload.feed_data(chunk[:required], required) chunk = chunk[required:] self._chunk = ChunkState.PARSE_CHUNKED_CHUNK_EOF self.payload.end_http_chunk_receiving() # toss the CRLF at the end of the chunk if self._chunk == ChunkState.PARSE_CHUNKED_CHUNK_EOF: if chunk[:2] == SEP: chunk = chunk[2:] self._chunk = ChunkState.PARSE_CHUNKED_SIZE else: self._chunk_tail = chunk return False, b"" # if stream does not contain trailer, after 0\r\n # we should get another \r\n otherwise # trailers needs to be skiped until \r\n\r\n if self._chunk == ChunkState.PARSE_MAYBE_TRAILERS: head = chunk[:2] if head == SEP: # end of stream self.payload.feed_eof() return True, chunk[2:] # Both CR and LF, or only LF may not be received yet. It is # expected that CRLF or LF will be shown at the very first # byte next time, otherwise trailers should come. The last # CRLF which marks the end of response might not be # contained in the same TCP segment which delivered the # size indicator. if not head: return False, b"" if head == SEP[:1]: self._chunk_tail = head return False, b"" self._chunk = ChunkState.PARSE_TRAILERS # read and discard trailer up to the CRLF terminator if self._chunk == ChunkState.PARSE_TRAILERS: pos = chunk.find(SEP) if pos >= 0: chunk = chunk[pos + 2 :] self._chunk = ChunkState.PARSE_MAYBE_TRAILERS else: self._chunk_tail = chunk return False, b"" # Read all bytes until eof elif self._type == ParseState.PARSE_UNTIL_EOF: self.payload.feed_data(chunk, len(chunk)) return False, b"" class DeflateBuffer: """DeflateStream decompress stream and feed data into specified stream.""" decompressor: Any def __init__(self, out: StreamReader, encoding: Optional[str]) -> None: self.out = out self.size = 0 self.encoding = encoding self._started_decoding = False if encoding == "br": if not HAS_BROTLI: # pragma: no cover raise ContentEncodingError( "Can not decode content-encoding: brotli (br). " "Please install `Brotli`" ) class BrotliDecoder: # 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: self._obj = brotli.Decompressor() def decompress(self, data: bytes) -> bytes: if hasattr(self._obj, "decompress"): return cast(bytes, self._obj.decompress(data)) return cast(bytes, self._obj.process(data)) def flush(self) -> bytes: if hasattr(self._obj, "flush"): return cast(bytes, self._obj.flush()) return b"" self.decompressor = BrotliDecoder() else: zlib_mode = 16 + zlib.MAX_WBITS if encoding == "gzip" else zlib.MAX_WBITS self.decompressor = zlib.decompressobj(wbits=zlib_mode) def set_exception(self, exc: BaseException) -> None: self.out.set_exception(exc) def feed_data(self, chunk: bytes, size: int) -> None: if not size: return self.size += size # RFC1950 # bits 0..3 = CM = 0b1000 = 8 = "deflate" # bits 4..7 = CINFO = 1..7 = windows size. if ( not self._started_decoding and self.encoding == "deflate" and chunk[0] & 0xF != 8 ): # Change the decoder to decompress incorrectly compressed data # Actually we should issue a warning about non-RFC-compliant data. self.decompressor = zlib.decompressobj(wbits=-zlib.MAX_WBITS) try: chunk = self.decompressor.decompress(chunk) except Exception: raise ContentEncodingError( "Can not decode content-encoding: %s" % self.encoding ) self._started_decoding = True if chunk: self.out.feed_data(chunk, len(chunk)) def feed_eof(self) -> None: chunk = self.decompressor.flush() if chunk or self.size > 0: self.out.feed_data(chunk, len(chunk)) if self.encoding == "deflate" and not self.decompressor.eof: raise ContentEncodingError("deflate") self.out.feed_eof() def begin_http_chunk_receiving(self) -> None: self.out.begin_http_chunk_receiving() def end_http_chunk_receiving(self) -> None: self.out.end_http_chunk_receiving() HttpRequestParserPy = HttpRequestParser HttpResponseParserPy = HttpResponseParser RawRequestMessagePy = RawRequestMessage RawResponseMessagePy = RawResponseMessage try: if not NO_EXTENSIONS: from ._http_parser import ( # type: ignore[import,no-redef] HttpRequestParser, HttpResponseParser, RawRequestMessage, RawResponseMessage, ) HttpRequestParserC = HttpRequestParser HttpResponseParserC = HttpResponseParser RawRequestMessageC = RawRequestMessage RawResponseMessageC = RawResponseMessage except ImportError: # pragma: no cover pass