forked-synapse/synapse/http/servlet.py
Eric Eastwood ac3e02d089
Add parse_strings_from_args to get prev_events array (#10048)
Split out from https://github.com/matrix-org/synapse/pull/9247

Strings:

 - `parse_string`
 - `parse_string_from_args`
 - `parse_strings_from_args`

For comparison with ints:

 - `parse_integer`
 - `parse_integer_from_args`

Previous discussions:

 - https://github.com/matrix-org/synapse/pull/9247#discussion_r573195687
 - https://github.com/matrix-org/synapse/pull/9247#discussion_r574214156
 - https://github.com/matrix-org/synapse/pull/9247#discussion_r573264791

Signed-off-by: Eric Eastwood <erice@element.io>
2021-05-28 14:19:06 +01:00

404 lines
13 KiB
Python

# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
""" This module contains base REST classes for constructing REST servlets. """
import logging
from typing import Iterable, List, Optional, Union, overload
from typing_extensions import Literal
from synapse.api.errors import Codes, SynapseError
from synapse.util import json_decoder
logger = logging.getLogger(__name__)
def parse_integer(request, name, default=None, required=False):
"""Parse an integer parameter from the request string
Args:
request: the twisted HTTP request.
name (bytes/unicode): the name of the query parameter.
default (int|None): value to use if the parameter is absent, defaults
to None.
required (bool): whether to raise a 400 SynapseError if the
parameter is absent, defaults to False.
Returns:
int|None: An int value or the default.
Raises:
SynapseError: if the parameter is absent and required, or if the
parameter is present and not an integer.
"""
return parse_integer_from_args(request.args, name, default, required)
def parse_integer_from_args(args, name, default=None, required=False):
if not isinstance(name, bytes):
name = name.encode("ascii")
if name in args:
try:
return int(args[name][0])
except Exception:
message = "Query parameter %r must be an integer" % (name,)
raise SynapseError(400, message, errcode=Codes.INVALID_PARAM)
else:
if required:
message = "Missing integer query parameter %r" % (name,)
raise SynapseError(400, message, errcode=Codes.MISSING_PARAM)
else:
return default
def parse_boolean(request, name, default=None, required=False):
"""Parse a boolean parameter from the request query string
Args:
request: the twisted HTTP request.
name (bytes/unicode): the name of the query parameter.
default (bool|None): value to use if the parameter is absent, defaults
to None.
required (bool): whether to raise a 400 SynapseError if the
parameter is absent, defaults to False.
Returns:
bool|None: A bool value or the default.
Raises:
SynapseError: if the parameter is absent and required, or if the
parameter is present and not one of "true" or "false".
"""
return parse_boolean_from_args(request.args, name, default, required)
def parse_boolean_from_args(args, name, default=None, required=False):
if not isinstance(name, bytes):
name = name.encode("ascii")
if name in args:
try:
return {b"true": True, b"false": False}[args[name][0]]
except Exception:
message = (
"Boolean query parameter %r must be one of ['true', 'false']"
) % (name,)
raise SynapseError(400, message)
else:
if required:
message = "Missing boolean query parameter %r" % (name,)
raise SynapseError(400, message, errcode=Codes.MISSING_PARAM)
else:
return default
def parse_string(
request,
name: Union[bytes, str],
default: Optional[str] = None,
required: bool = False,
allowed_values: Optional[Iterable[str]] = None,
encoding: Optional[str] = "ascii",
):
"""
Parse a string parameter from the request query string.
If encoding is not None, the content of the query param will be
decoded to Unicode using the encoding, otherwise it will be encoded
Args:
request: the twisted HTTP request.
name: the name of the query parameter.
default: value to use if the parameter is absent,
defaults to None. Must be bytes if encoding is None.
required: whether to raise a 400 SynapseError if the
parameter is absent, defaults to False.
allowed_values: List of allowed values for the
string, or None if any value is allowed, defaults to None. Must be
the same type as name, if given.
encoding : The encoding to decode the string content with.
Returns:
A string value or the default. Unicode if encoding
was given, bytes otherwise.
Raises:
SynapseError if the parameter is absent and required, or if the
parameter is present, must be one of a list of allowed values and
is not one of those allowed values.
"""
return parse_string_from_args(
request.args, name, default, required, allowed_values, encoding
)
def _parse_string_value(
value: Union[str, bytes],
allowed_values: Optional[Iterable[str]],
name: str,
encoding: Optional[str],
) -> Union[str, bytes]:
if encoding:
try:
value = value.decode(encoding)
except ValueError:
raise SynapseError(400, "Query parameter %r must be %s" % (name, encoding))
if allowed_values is not None and value not in allowed_values:
message = "Query parameter %r must be one of [%s]" % (
name,
", ".join(repr(v) for v in allowed_values),
)
raise SynapseError(400, message)
else:
return value
@overload
def parse_strings_from_args(
args: List[str],
name: Union[bytes, str],
default: Optional[List[str]] = None,
required: bool = False,
allowed_values: Optional[Iterable[str]] = None,
encoding: Literal[None] = None,
) -> Optional[List[bytes]]:
...
@overload
def parse_strings_from_args(
args: List[str],
name: Union[bytes, str],
default: Optional[List[str]] = None,
required: bool = False,
allowed_values: Optional[Iterable[str]] = None,
encoding: str = "ascii",
) -> Optional[List[str]]:
...
def parse_strings_from_args(
args: List[str],
name: Union[bytes, str],
default: Optional[List[str]] = None,
required: bool = False,
allowed_values: Optional[Iterable[str]] = None,
encoding: Optional[str] = "ascii",
) -> Optional[List[Union[bytes, str]]]:
"""
Parse a string parameter from the request query string list.
If encoding is not None, the content of the query param will be
decoded to Unicode using the encoding, otherwise it will be encoded
Args:
args: the twisted HTTP request.args list.
name: the name of the query parameter.
default: value to use if the parameter is absent,
defaults to None. Must be bytes if encoding is None.
required : whether to raise a 400 SynapseError if the
parameter is absent, defaults to False.
allowed_values (list[bytes|unicode]): List of allowed values for the
string, or None if any value is allowed, defaults to None. Must be
the same type as name, if given.
encoding: The encoding to decode the string content with.
Returns:
A string value or the default. Unicode if encoding
was given, bytes otherwise.
Raises:
SynapseError if the parameter is absent and required, or if the
parameter is present, must be one of a list of allowed values and
is not one of those allowed values.
"""
if not isinstance(name, bytes):
name = name.encode("ascii")
if name in args:
values = args[name]
return [
_parse_string_value(value, allowed_values, name=name, encoding=encoding)
for value in values
]
else:
if required:
message = "Missing string query parameter %r" % (name)
raise SynapseError(400, message, errcode=Codes.MISSING_PARAM)
else:
if encoding and isinstance(default, bytes):
return default.decode(encoding)
return default
def parse_string_from_args(
args: List[str],
name: Union[bytes, str],
default: Optional[str] = None,
required: bool = False,
allowed_values: Optional[Iterable[str]] = None,
encoding: Optional[str] = "ascii",
) -> Optional[Union[bytes, str]]:
"""
Parse the string parameter from the request query string list
and return the first result.
If encoding is not None, the content of the query param will be
decoded to Unicode using the encoding, otherwise it will be encoded
Args:
args: the twisted HTTP request.args list.
name: the name of the query parameter.
default: value to use if the parameter is absent,
defaults to None. Must be bytes if encoding is None.
required: whether to raise a 400 SynapseError if the
parameter is absent, defaults to False.
allowed_values: List of allowed values for the
string, or None if any value is allowed, defaults to None. Must be
the same type as name, if given.
encoding: The encoding to decode the string content with.
Returns:
A string value or the default. Unicode if encoding
was given, bytes otherwise.
Raises:
SynapseError if the parameter is absent and required, or if the
parameter is present, must be one of a list of allowed values and
is not one of those allowed values.
"""
strings = parse_strings_from_args(
args,
name,
default=[default],
required=required,
allowed_values=allowed_values,
encoding=encoding,
)
return strings[0]
def parse_json_value_from_request(request, allow_empty_body=False):
"""Parse a JSON value from the body of a twisted HTTP request.
Args:
request: the twisted HTTP request.
allow_empty_body (bool): if True, an empty body will be accepted and
turned into None
Returns:
The JSON value.
Raises:
SynapseError if the request body couldn't be decoded as JSON.
"""
try:
content_bytes = request.content.read()
except Exception:
raise SynapseError(400, "Error reading JSON content.")
if not content_bytes and allow_empty_body:
return None
try:
content = json_decoder.decode(content_bytes.decode("utf-8"))
except Exception as e:
logger.warning("Unable to parse JSON: %s (%s)", e, content_bytes)
raise SynapseError(400, "Content not JSON.", errcode=Codes.NOT_JSON)
return content
def parse_json_object_from_request(request, allow_empty_body=False):
"""Parse a JSON object from the body of a twisted HTTP request.
Args:
request: the twisted HTTP request.
allow_empty_body (bool): if True, an empty body will be accepted and
turned into an empty dict.
Raises:
SynapseError if the request body couldn't be decoded as JSON or
if it wasn't a JSON object.
"""
content = parse_json_value_from_request(request, allow_empty_body=allow_empty_body)
if allow_empty_body and content is None:
return {}
if type(content) != dict:
message = "Content must be a JSON object."
raise SynapseError(400, message, errcode=Codes.BAD_JSON)
return content
def assert_params_in_dict(body, required):
absent = []
for k in required:
if k not in body:
absent.append(k)
if len(absent) > 0:
raise SynapseError(400, "Missing params: %r" % absent, Codes.MISSING_PARAM)
class RestServlet:
"""A Synapse REST Servlet.
An implementing class can either provide its own custom 'register' method,
or use the automatic pattern handling provided by the base class.
To use this latter, the implementing class instead provides a `PATTERN`
class attribute containing a pre-compiled regular expression. The automatic
register method will then use this method to register any of the following
instance methods associated with the corresponding HTTP method:
on_GET
on_PUT
on_POST
on_DELETE
Automatically handles turning CodeMessageExceptions thrown by these methods
into the appropriate HTTP response.
"""
def register(self, http_server):
""" Register this servlet with the given HTTP server. """
if hasattr(self, "PATTERNS"):
patterns = self.PATTERNS
for method in ("GET", "PUT", "POST", "DELETE"):
if hasattr(self, "on_%s" % (method,)):
servlet_classname = self.__class__.__name__
method_handler = getattr(self, "on_%s" % (method,))
http_server.register_paths(
method, patterns, method_handler, servlet_classname
)
else:
raise NotImplementedError("RestServlet must register something.")