web_response.py

import asyncio
import collections.abc
import datetime
import enum
import json
import math
import time
import warnings
import zlib
from concurrent.futures import Executor
from email.utils import parsedate
from http.cookies import Morsel
from typing import (
    TYPE_CHECKING,
    Any,
    Dict,
    Iterator,
    Mapping,
    MutableMapping,
    Optional,
    Tuple,
    Union,
    cast,
)

from multidict import CIMultiDict, istr

from . import hdrs, payload
from .abc import AbstractStreamWriter
from .helpers import (
    ETAG_ANY,
    PY_38,
    QUOTED_ETAG_RE,
    CookieMixin,
    ETag,
    HeadersMixin,
    populate_with_cookies,
    rfc822_formatted_time,
    sentinel,
    validate_etag_value,
)
from .http import RESPONSES, SERVER_SOFTWARE, HttpVersion10, HttpVersion11
from .payload import Payload
from .typedefs import JSONEncoder, LooseHeaders

__all__ = ("ContentCoding", "StreamResponse", "Response", "json_response")


if TYPE_CHECKING:  # pragma: no cover
    from .web_request import BaseRequest

    BaseClass = MutableMapping[str, Any]
else:
    BaseClass = collections.abc.MutableMapping


if not PY_38:
    # allow samesite to be used in python < 3.8
    # already permitted in python 3.8, see https://bugs.python.org/issue29613
    Morsel._reserved["samesite"] = "SameSite"  # type: ignore[attr-defined]


class ContentCoding(enum.Enum):
    # The content codings that we have support for.
    #
    # Additional registered codings are listed at:
    # https://www.iana.org/assignments/http-parameters/http-parameters.xhtml#content-coding
    deflate = "deflate"
    gzip = "gzip"
    identity = "identity"


############################################################
# HTTP Response classes
############################################################


class StreamResponse(BaseClass, HeadersMixin, CookieMixin):

    __slots__ = (
        "_length_check",
        "_body",
        "_keep_alive",
        "_chunked",
        "_compression",
        "_compression_force",
        "_req",
        "_payload_writer",
        "_eof_sent",
        "_body_length",
        "_state",
        "_headers",
        "_status",
        "_reason",
        "__weakref__",
    )

    def __init__(
        self,
        *,
        status: int = 200,
        reason: Optional[str] = None,
        headers: Optional[LooseHeaders] = None,
    ) -> None:
        super().__init__()
        self._length_check = True
        self._body = None
        self._keep_alive = None  # type: Optional[bool]
        self._chunked = False
        self._compression = False
        self._compression_force = None  # type: Optional[ContentCoding]

        self._req = None  # type: Optional[BaseRequest]
        self._payload_writer = None  # type: Optional[AbstractStreamWriter]
        self._eof_sent = False
        self._body_length = 0
        self._state = {}  # type: Dict[str, Any]

        if headers is not None:
            self._headers = CIMultiDict(headers)  # type: CIMultiDict[str]
        else:
            self._headers = CIMultiDict()

        self.set_status(status, reason)

    @property
    def prepared(self) -> bool:
        return self._payload_writer is not None

    @property
    def task(self) -> "Optional[asyncio.Task[None]]":
        if self._req:
            return self._req.task
        else:
            return None

    @property
    def status(self) -> int:
        return self._status

    @property
    def chunked(self) -> bool:
        return self._chunked

    @property
    def compression(self) -> bool:
        return self._compression

    @property
    def reason(self) -> str:
        return self._reason

    def set_status(
        self,
        status: int,
        reason: Optional[str] = None,
        _RESPONSES: Mapping[int, Tuple[str, str]] = RESPONSES,
    ) -> None:
        assert not self.prepared, (
            "Cannot change the response status code after " "the headers have been sent"
        )
        self._status = int(status)
        if reason is None:
            try:
                reason = _RESPONSES[self._status][0]
            except Exception:
                reason = ""
        self._reason = reason

    @property
    def keep_alive(self) -> Optional[bool]:
        return self._keep_alive

    def force_close(self) -> None:
        self._keep_alive = False

    @property
    def body_length(self) -> int:
        return self._body_length

    def enable_chunked_encoding(self) -> None:
        """Enables automatic chunked transfer encoding."""
        self._chunked = True

        if hdrs.CONTENT_LENGTH in self._headers:
            raise RuntimeError(
                "You can't enable chunked encoding when " "a content length is set"
            )

    def enable_compression(self, force: Optional[ContentCoding] = None) -> None:
        """Enables response compression encoding."""
        # Backwards compatibility for when force was a bool <0.17.
        self._compression = True
        self._compression_force = force

    @property
    def headers(self) -> "CIMultiDict[str]":
        return self._headers

    @property
    def content_length(self) -> Optional[int]:
        # Just a placeholder for adding setter
        return super().content_length

    @content_length.setter
    def content_length(self, value: Optional[int]) -> None:
        if value is not None:
            value = int(value)
            if self._chunked:
                raise RuntimeError(
                    "You can't set content length when " "chunked encoding is enable"
                )
            self._headers[hdrs.CONTENT_LENGTH] = str(value)
        else:
            self._headers.pop(hdrs.CONTENT_LENGTH, None)

    @property
    def content_type(self) -> str:
        # Just a placeholder for adding setter
        return super().content_type

    @content_type.setter
    def content_type(self, value: str) -> None:
        self.content_type  # read header values if needed
        self._content_type = str(value)
        self._generate_content_type_header()

    @property
    def charset(self) -> Optional[str]:
        # Just a placeholder for adding setter
        return super().charset

    @charset.setter
    def charset(self, value: Optional[str]) -> None:
        ctype = self.content_type  # read header values if needed
        if ctype == "application/octet-stream":
            raise RuntimeError(
                "Setting charset for application/octet-stream "
                "doesn't make sense, setup content_type first"
            )
        assert self._content_dict is not None
        if value is None:
            self._content_dict.pop("charset", None)
        else:
            self._content_dict["charset"] = str(value).lower()
        self._generate_content_type_header()

    @property
    def last_modified(self) -> Optional[datetime.datetime]:
        """The value of Last-Modified HTTP header, or None.

        This header is represented as a `datetime` object.
        """
        httpdate = self._headers.get(hdrs.LAST_MODIFIED)
        if httpdate is not None:
            timetuple = parsedate(httpdate)
            if timetuple is not None:
                return datetime.datetime(*timetuple[:6], tzinfo=datetime.timezone.utc)
        return None

    @last_modified.setter
    def last_modified(
        self, value: Optional[Union[int, float, datetime.datetime, str]]
    ) -> None:
        if value is None:
            self._headers.pop(hdrs.LAST_MODIFIED, None)
        elif isinstance(value, (int, float)):
            self._headers[hdrs.LAST_MODIFIED] = time.strftime(
                "%a, %d %b %Y %H:%M:%S GMT", time.gmtime(math.ceil(value))
            )
        elif isinstance(value, datetime.datetime):
            self._headers[hdrs.LAST_MODIFIED] = time.strftime(
                "%a, %d %b %Y %H:%M:%S GMT", value.utctimetuple()
            )
        elif isinstance(value, str):
            self._headers[hdrs.LAST_MODIFIED] = value

    @property
    def etag(self) -> Optional[ETag]:
        quoted_value = self._headers.get(hdrs.ETAG)
        if not quoted_value:
            return None
        elif quoted_value == ETAG_ANY:
            return ETag(value=ETAG_ANY)
        match = QUOTED_ETAG_RE.fullmatch(quoted_value)
        if not match:
            return None
        is_weak, value = match.group(1, 2)
        return ETag(
            is_weak=bool(is_weak),
            value=value,
        )

    @etag.setter
    def etag(self, value: Optional[Union[ETag, str]]) -> None:
        if value is None:
            self._headers.pop(hdrs.ETAG, None)
        elif (isinstance(value, str) and value == ETAG_ANY) or (
            isinstance(value, ETag) and value.value == ETAG_ANY
        ):
            self._headers[hdrs.ETAG] = ETAG_ANY
        elif isinstance(value, str):
            validate_etag_value(value)
            self._headers[hdrs.ETAG] = f'"{value}"'
        elif isinstance(value, ETag) and isinstance(value.value, str):
            validate_etag_value(value.value)
            hdr_value = f'W/"{value.value}"' if value.is_weak else f'"{value.value}"'
            self._headers[hdrs.ETAG] = hdr_value
        else:
            raise ValueError(
                f"Unsupported etag type: {type(value)}. "
                f"etag must be str, ETag or None"
            )

    def _generate_content_type_header(
        self, CONTENT_TYPE: istr = hdrs.CONTENT_TYPE
    ) -> None:
        assert self._content_dict is not None
        assert self._content_type is not None
        params = "; ".join(f"{k}={v}" for k, v in self._content_dict.items())
        if params:
            ctype = self._content_type + "; " + params
        else:
            ctype = self._content_type
        self._headers[CONTENT_TYPE] = ctype

    async def _do_start_compression(self, coding: ContentCoding) -> None:
        if coding != ContentCoding.identity:
            assert self._payload_writer is not None
            self._headers[hdrs.CONTENT_ENCODING] = coding.value
            self._payload_writer.enable_compression(coding.value)
            # Compressed payload may have different content length,
            # remove the header
            self._headers.popall(hdrs.CONTENT_LENGTH, None)

    async def _start_compression(self, request: "BaseRequest") -> None:
        if self._compression_force:
            await self._do_start_compression(self._compression_force)
        else:
            accept_encoding = request.headers.get(hdrs.ACCEPT_ENCODING, "").lower()
            for coding in ContentCoding:
                if coding.value in accept_encoding:
                    await self._do_start_compression(coding)
                    return

    async def prepare(self, request: "BaseRequest") -> Optional[AbstractStreamWriter]:
        if self._eof_sent:
            return None
        if self._payload_writer is not None:
            return self._payload_writer

        return await self._start(request)

    async def _start(self, request: "BaseRequest") -> AbstractStreamWriter:
        self._req = request
        writer = self._payload_writer = request._payload_writer

        await self._prepare_headers()
        await request._prepare_hook(self)
        await self._write_headers()

        return writer

    async def _prepare_headers(self) -> None:
        request = self._req
        assert request is not None
        writer = self._payload_writer
        assert writer is not None
        keep_alive = self._keep_alive
        if keep_alive is None:
            keep_alive = request.keep_alive
        self._keep_alive = keep_alive

        version = request.version

        headers = self._headers
        populate_with_cookies(headers, self.cookies)

        if self._compression:
            await self._start_compression(request)

        if self._chunked:
            if version != HttpVersion11:
                raise RuntimeError(
                    "Using chunked encoding is forbidden "
                    "for HTTP/{0.major}.{0.minor}".format(request.version)
                )
            writer.enable_chunking()
            headers[hdrs.TRANSFER_ENCODING] = "chunked"
            if hdrs.CONTENT_LENGTH in headers:
                del headers[hdrs.CONTENT_LENGTH]
        elif self._length_check:
            writer.length = self.content_length
            if writer.length is None:
                if version >= HttpVersion11 and self.status != 204:
                    writer.enable_chunking()
                    headers[hdrs.TRANSFER_ENCODING] = "chunked"
                    if hdrs.CONTENT_LENGTH in headers:
                        del headers[hdrs.CONTENT_LENGTH]
                else:
                    keep_alive = False
            # HTTP 1.1: https://tools.ietf.org/html/rfc7230#section-3.3.2
            # HTTP 1.0: https://tools.ietf.org/html/rfc1945#section-10.4
            elif version >= HttpVersion11 and self.status in (100, 101, 102, 103, 204):
                del headers[hdrs.CONTENT_LENGTH]

        if self.status not in (204, 304):
            headers.setdefault(hdrs.CONTENT_TYPE, "application/octet-stream")
        headers.setdefault(hdrs.DATE, rfc822_formatted_time())
        headers.setdefault(hdrs.SERVER, SERVER_SOFTWARE)

        # connection header
        if hdrs.CONNECTION not in headers:
            if keep_alive:
                if version == HttpVersion10:
                    headers[hdrs.CONNECTION] = "keep-alive"
            else:
                if version == HttpVersion11:
                    headers[hdrs.CONNECTION] = "close"

    async def _write_headers(self) -> None:
        request = self._req
        assert request is not None
        writer = self._payload_writer
        assert writer is not None
        # status line
        version = request.version
        status_line = "HTTP/{}.{} {} {}".format(
            version[0], version[1], self._status, self._reason
        )
        await writer.write_headers(status_line, self._headers)

    async def write(self, data: bytes) -> None:
        assert isinstance(
            data, (bytes, bytearray, memoryview)
        ), "data argument must be byte-ish (%r)" % type(data)

        if self._eof_sent:
            raise RuntimeError("Cannot call write() after write_eof()")
        if self._payload_writer is None:
            raise RuntimeError("Cannot call write() before prepare()")

        await self._payload_writer.write(data)

    async def drain(self) -> None:
        assert not self._eof_sent, "EOF has already been sent"
        assert self._payload_writer is not None, "Response has not been started"
        warnings.warn(
            "drain method is deprecated, use await resp.write()",
            DeprecationWarning,
            stacklevel=2,
        )
        await self._payload_writer.drain()

    async def write_eof(self, data: bytes = b"") -> None:
        assert isinstance(
            data, (bytes, bytearray, memoryview)
        ), "data argument must be byte-ish (%r)" % type(data)

        if self._eof_sent:
            return

        assert self._payload_writer is not None, "Response has not been started"

        await self._payload_writer.write_eof(data)
        self._eof_sent = True
        self._req = None
        self._body_length = self._payload_writer.output_size
        self._payload_writer = None

    def __repr__(self) -> str:
        if self._eof_sent:
            info = "eof"
        elif self.prepared:
            assert self._req is not None
            info = f"{self._req.method} {self._req.path} "
        else:
            info = "not prepared"
        return f"<{self.__class__.__name__} {self.reason} {info}>"

    def __getitem__(self, key: str) -> Any:
        return self._state[key]

    def __setitem__(self, key: str, value: Any) -> None:
        self._state[key] = value

    def __delitem__(self, key: str) -> None:
        del self._state[key]

    def __len__(self) -> int:
        return len(self._state)

    def __iter__(self) -> Iterator[str]:
        return iter(self._state)

    def __hash__(self) -> int:
        return hash(id(self))

    def __eq__(self, other: object) -> bool:
        return self is other


class Response(StreamResponse):

    __slots__ = (
        "_body_payload",
        "_compressed_body",
        "_zlib_executor_size",
        "_zlib_executor",
    )

    def __init__(
        self,
        *,
        body: Any = None,
        status: int = 200,
        reason: Optional[str] = None,
        text: Optional[str] = None,
        headers: Optional[LooseHeaders] = None,
        content_type: Optional[str] = None,
        charset: Optional[str] = None,
        zlib_executor_size: Optional[int] = None,
        zlib_executor: Optional[Executor] = None,
    ) -> None:
        if body is not None and text is not None:
            raise ValueError("body and text are not allowed together")

        if headers is None:
            real_headers = CIMultiDict()  # type: CIMultiDict[str]
        elif not isinstance(headers, CIMultiDict):
            real_headers = CIMultiDict(headers)
        else:
            real_headers = headers  # = cast('CIMultiDict[str]', headers)

        if content_type is not None and "charset" in content_type:
            raise ValueError("charset must not be in content_type " "argument")

        if text is not None:
            if hdrs.CONTENT_TYPE in real_headers:
                if content_type or charset:
                    raise ValueError(
                        "passing both Content-Type header and "
                        "content_type or charset params "
                        "is forbidden"
                    )
            else:
                # fast path for filling headers
                if not isinstance(text, str):
                    raise TypeError("text argument must be str (%r)" % type(text))
                if content_type is None:
                    content_type = "text/plain"
                if charset is None:
                    charset = "utf-8"
                real_headers[hdrs.CONTENT_TYPE] = content_type + "; charset=" + charset
                body = text.encode(charset)
                text = None
        else:
            if hdrs.CONTENT_TYPE in real_headers:
                if content_type is not None or charset is not None:
                    raise ValueError(
                        "passing both Content-Type header and "
                        "content_type or charset params "
                        "is forbidden"
                    )
            else:
                if content_type is not None:
                    if charset is not None:
                        content_type += "; charset=" + charset
                    real_headers[hdrs.CONTENT_TYPE] = content_type

        super().__init__(status=status, reason=reason, headers=real_headers)

        if text is not None:
            self.text = text
        else:
            self.body = body

        self._compressed_body = None  # type: Optional[bytes]
        self._zlib_executor_size = zlib_executor_size
        self._zlib_executor = zlib_executor

    @property
    def body(self) -> Optional[Union[bytes, Payload]]:
        return self._body

    @body.setter
    def body(
        self,
        body: bytes,
        CONTENT_TYPE: istr = hdrs.CONTENT_TYPE,
        CONTENT_LENGTH: istr = hdrs.CONTENT_LENGTH,
    ) -> None:
        if body is None:
            self._body = None  # type: Optional[bytes]
            self._body_payload = False  # type: bool
        elif isinstance(body, (bytes, bytearray)):
            self._body = body
            self._body_payload = False
        else:
            try:
                self._body = body = payload.PAYLOAD_REGISTRY.get(body)
            except payload.LookupError:
                raise ValueError("Unsupported body type %r" % type(body))

            self._body_payload = True

            headers = self._headers

            # set content-length header if needed
            if not self._chunked and CONTENT_LENGTH not in headers:
                size = body.size
                if size is not None:
                    headers[CONTENT_LENGTH] = str(size)

            # set content-type
            if CONTENT_TYPE not in headers:
                headers[CONTENT_TYPE] = body.content_type

            # copy payload headers
            if body.headers:
                for (key, value) in body.headers.items():
                    if key not in headers:
                        headers[key] = value

        self._compressed_body = None

    @property
    def text(self) -> Optional[str]:
        if self._body is None:
            return None
        return self._body.decode(self.charset or "utf-8")

    @text.setter
    def text(self, text: str) -> None:
        assert text is None or isinstance(
            text, str
        ), "text argument must be str (%r)" % type(text)

        if self.content_type == "application/octet-stream":
            self.content_type = "text/plain"
        if self.charset is None:
            self.charset = "utf-8"

        self._body = text.encode(self.charset)
        self._body_payload = False
        self._compressed_body = None

    @property
    def content_length(self) -> Optional[int]:
        if self._chunked:
            return None

        if hdrs.CONTENT_LENGTH in self._headers:
            return super().content_length

        if self._compressed_body is not None:
            # Return length of the compressed body
            return len(self._compressed_body)
        elif self._body_payload:
            # A payload without content length, or a compressed payload
            return None
        elif self._body is not None:
            return len(self._body)
        else:
            return 0

    @content_length.setter
    def content_length(self, value: Optional[int]) -> None:
        raise RuntimeError("Content length is set automatically")

    async def write_eof(self, data: bytes = b"") -> None:
        if self._eof_sent:
            return
        if self._compressed_body is None:
            body = self._body  # type: Optional[Union[bytes, Payload]]
        else:
            body = self._compressed_body
        assert not data, f"data arg is not supported, got {data!r}"
        assert self._req is not None
        assert self._payload_writer is not None
        if body is not None:
            if self._req._method == hdrs.METH_HEAD or self._status in [204, 304]:
                await super().write_eof()
            elif self._body_payload:
                payload = cast(Payload, body)
                await payload.write(self._payload_writer)
                await super().write_eof()
            else:
                await super().write_eof(cast(bytes, body))
        else:
            await super().write_eof()

    async def _start(self, request: "BaseRequest") -> AbstractStreamWriter:
        if not self._chunked and hdrs.CONTENT_LENGTH not in self._headers:
            if not self._body_payload:
                if self._body is not None:
                    self._headers[hdrs.CONTENT_LENGTH] = str(len(self._body))
                else:
                    self._headers[hdrs.CONTENT_LENGTH] = "0"

        return await super()._start(request)

    def _compress_body(self, zlib_mode: int) -> None:
        assert zlib_mode > 0
        compressobj = zlib.compressobj(wbits=zlib_mode)
        body_in = self._body
        assert body_in is not None
        self._compressed_body = compressobj.compress(body_in) + compressobj.flush()

    async def _do_start_compression(self, coding: ContentCoding) -> None:
        if self._body_payload or self._chunked:
            return await super()._do_start_compression(coding)

        if coding != ContentCoding.identity:
            # Instead of using _payload_writer.enable_compression,
            # compress the whole body
            zlib_mode = (
                16 + zlib.MAX_WBITS if coding == ContentCoding.gzip else zlib.MAX_WBITS
            )
            body_in = self._body
            assert body_in is not None
            if (
                self._zlib_executor_size is not None
                and len(body_in) > self._zlib_executor_size
            ):
                await asyncio.get_event_loop().run_in_executor(
                    self._zlib_executor, self._compress_body, zlib_mode
                )
            else:
                self._compress_body(zlib_mode)

            body_out = self._compressed_body
            assert body_out is not None

            self._headers[hdrs.CONTENT_ENCODING] = coding.value
            self._headers[hdrs.CONTENT_LENGTH] = str(len(body_out))


def json_response(
    data: Any = sentinel,
    *,
    text: Optional[str] = None,
    body: Optional[bytes] = None,
    status: int = 200,
    reason: Optional[str] = None,
    headers: Optional[LooseHeaders] = None,
    content_type: str = "application/json",
    dumps: JSONEncoder = json.dumps,
) -> Response:
    if data is not sentinel:
        if text or body:
            raise ValueError("only one of data, text, or body should be specified")
        else:
            text = dumps(data)
    return Response(
        text=text,
        body=body,
        status=status,
        reason=reason,
        headers=headers,
        content_type=content_type,
    )