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#
# 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.
from six import PY3
from six.moves import http_client, urllib
from canonicaljson import encode_canonical_json, encode_pretty_printed_json, json
from twisted.python import failure
from twisted.web.static import NoRangeStaticProducer
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from twisted.web.util import redirectTo
import synapse.events
import synapse.metrics
from synapse.api.errors import (
CodeMessageException,
Codes,
SynapseError,
UnrecognizedRequestError,
)
from synapse.util.caches import intern_dict
from synapse.util.logcontext import preserve_fn
if PY3:
from io import BytesIO
else:
from cStringIO import StringIO as BytesIO
HTML_ERROR_TEMPLATE = """<!DOCTYPE html>
<html lang=en>
<head>
<meta charset="utf-8">
<title>Error {code}</title>
</head>
<body>
<p>{msg}</p>
</body>
</html>
"""
def wrap_json_request_handler(h):
"""Wraps a request handler method with exception handling.
Also does the wrapping with request.processing as per wrap_async_request_handler.
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The handler method must have a signature of "handle_foo(self, request)",
where "request" must be a SynapseRequest.
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The handler must return a deferred. If the deferred succeeds we assume that
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a response has been sent. If the deferred fails with a SynapseError we use
it to send a JSON response with the appropriate HTTP reponse code. If the
deferred fails with any other type of error we send a 500 reponse.
"""
@defer.inlineCallbacks
def wrapped_request_handler(self, request):
try:
yield h(self, request)
except SynapseError as e:
code = e.code
logger.info(
"%s SynapseError: %s - %s", request, code, e.msg
)
# Only respond with an error response if we haven't already started
# writing, otherwise lets just kill the connection
if request.startedWriting:
if request.transport:
try:
request.transport.abortConnection()
except Exception:
# abortConnection throws if the connection is already closed
pass
else:
respond_with_json(
request, code, e.error_dict(), send_cors=True,
pretty_print=_request_user_agent_is_curl(request),
)
except Exception:
# failure.Failure() fishes the original Failure out
# of our stack, and thus gives us a sensible stack
# trace.
f = failure.Failure()
logger.error(
"Failed handle request via %r: %r",
request.request_metrics.name,
request,
exc_info=(f.type, f.value, f.getTracebackObject()),
)
# Only respond with an error response if we haven't already started
# writing, otherwise lets just kill the connection
if request.startedWriting:
if request.transport:
try:
request.transport.abortConnection()
except Exception:
# abortConnection throws if the connection is already closed
pass
else:
respond_with_json(
request,
500,
{
"error": "Internal server error",
"errcode": Codes.UNKNOWN,
},
send_cors=True,
pretty_print=_request_user_agent_is_curl(request),
)
return wrap_async_request_handler(wrapped_request_handler)
def wrap_html_request_handler(h):
"""Wraps a request handler method with exception handling.
Also does the wrapping with request.processing as per wrap_async_request_handler.
The handler method must have a signature of "handle_foo(self, request)",
where "request" must be a SynapseRequest.
"""
def wrapped_request_handler(self, request):
d = defer.maybeDeferred(h, self, request)
d.addErrback(_return_html_error, request)
return d
return wrap_async_request_handler(wrapped_request_handler)
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def _return_html_error(f, request):
"""Sends an HTML error page corresponding to the given failure
Args:
f (twisted.python.failure.Failure):
request (twisted.web.iweb.IRequest):
"""
if f.check(CodeMessageException):
cme = f.value
code = cme.code
msg = cme.msg
if isinstance(cme, SynapseError):
logger.info(
"%s SynapseError: %s - %s", request, code, msg
)
else:
logger.error(
"Failed handle request %r: %s",
request,
f.getTraceback().rstrip(),
)
else:
code = http_client.INTERNAL_SERVER_ERROR
msg = "Internal server error"
logger.error(
"Failed handle request %r: %s",
request,
f.getTraceback().rstrip(),
)
body = HTML_ERROR_TEMPLATE.format(
code=code, msg=cgi.escape(msg),
).encode("utf-8")
request.setResponseCode(code)
request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
request.setHeader(b"Content-Length", b"%i" % (len(body),))
request.write(body)
finish_request(request)
def wrap_async_request_handler(h):
"""Wraps an async request handler so that it calls request.processing.
This helps ensure that work done by the request handler after the request is completed
is correctly recorded against the request metrics/logs.
The handler method must have a signature of "handle_foo(self, request)",
where "request" must be a SynapseRequest.
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The handler may return a deferred, in which case the completion of the request isn't
logged until the deferred completes.
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"""
@defer.inlineCallbacks
def wrapped_async_request_handler(self, request):
with request.processing():
yield h(self, request)
# we need to preserve_fn here, because the synchronous render method won't yield for
# us (obviously)
return preserve_fn(wrapped_async_request_handler)
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class HttpServer(object):
""" Interface for registering callbacks on a HTTP server
"""
def register_paths(self, method, path_patterns, callback):
""" Register a callback that gets fired if we receive a http request
with the given method for a path that matches the given regex.
If the regex contains groups these gets passed to the calback via
an unpacked tuple.
Args:
method (str): The method to listen to.
path_patterns (list<SRE_Pattern>): The regex used to match requests.
callback (function): The function to fire if we receive a matched
request. The first argument will be the request object and
subsequent arguments will be any matched groups from the regex.
This should return a tuple of (code, response).
"""
pass
class JsonResource(HttpServer, resource.Resource):
""" This implements the HttpServer interface and provides JSON support for
Resources.
Register callbacks via register_paths()
Callbacks can return a tuple of status code and a dict in which case the
the dict will automatically be sent to the client as a JSON object.
The JsonResource is primarily intended for returning JSON, but callbacks
may send something other than JSON, they may do so by using the methods
on the request object and instead returning None.
"""
isLeaf = True
_PathEntry = collections.namedtuple("_PathEntry", ["pattern", "callback"])
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def __init__(self, hs, canonical_json=True):
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self.canonical_json = canonical_json
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self.clock = hs.get_clock()
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self.hs = hs
def register_paths(self, method, path_patterns, callback):
method = method.encode("utf-8") # method is bytes on py3
for path_pattern in path_patterns:
logger.debug("Registering for %s %s", method, path_pattern.pattern)
self.path_regexs.setdefault(method, []).append(
self._PathEntry(path_pattern, callback)
)
""" This gets called by twisted every time someone sends us a request.
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self._async_render(request)
@wrap_json_request_handler
""" This gets called from render() every time someone sends us a request.
This checks if anyone has registered a callback for that method and
path.
"""
callback, group_dict = self._get_handler_for_request(request)
servlet_instance = getattr(callback, "__self__", None)
if servlet_instance is not None:
servlet_classname = servlet_instance.__class__.__name__
else:
servlet_classname = "%r" % callback
request.request_metrics.name = servlet_classname
# Now trigger the callback. If it returns a response, we send it
# here. If it throws an exception, that is handled by the wrapper
# installed by @request_handler.
def _unquote(s):
if PY3:
# On Python 3, unquote is unicode -> unicode
return urllib.parse.unquote(s)
else:
# On Python 2, unquote is bytes -> bytes We need to encode the
# URL again (as it was decoded by _get_handler_for request), as
# ASCII because it's a URL, and then decode it to get the UTF-8
# characters that were quoted.
return urllib.parse.unquote(s.encode('ascii')).decode('utf8')
name: _unquote(value) if value else value
for name, value in group_dict.items()
})
callback_return = yield callback(request, **kwargs)
if callback_return is not None:
code, response = callback_return
self._send_response(request, code, response)
def _get_handler_for_request(self, request):
"""Finds a callback method to handle the given request
Args:
request (twisted.web.http.Request):
Tuple[Callable, dict[unicode, unicode]]: callback method, and the
dict mapping keys to path components as specified in the
handler's path match regexp.
The callback will normally be a method registered via
register_paths, so will return (possibly via Deferred) either
None, or a tuple of (http code, response body).
if request.method == b"OPTIONS":
# Loop through all the registered callbacks to check if the method
# and path regex match
for path_entry in self.path_regexs.get(request.method, []):
m = path_entry.pattern.match(request.path.decode('ascii'))
if m:
# We found a match!
return path_entry.callback, m.groupdict()
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# Huh. No one wanted to handle that? Fiiiiiine. Send 400.
def _send_response(self, request, code, response_json_object,
response_code_message=None):
# TODO: Only enable CORS for the requests that need it.
respond_with_json(
request, code, response_json_object,
send_cors=True,
response_code_message=response_code_message,
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pretty_print=_request_user_agent_is_curl(request),
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canonical_json=self.canonical_json,
"""Request handler for OPTIONS requests
This is a request handler suitable for return from
_get_handler_for_request. It returns a 200 and an empty body.
Args:
request (twisted.web.http.Request):
Returns:
Tuple[int, dict]: http code, response body.
"""
return 200, {}
def _unrecognised_request_handler(request):
"""Request handler for unrecognised requests
This is a request handler suitable for return from
_get_handler_for_request. It actually just raises an
UnrecognizedRequestError.
Args:
request (twisted.web.http.Request):
"""
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class RootRedirect(resource.Resource):
"""Redirects the root '/' path to another path."""
def __init__(self, path):
resource.Resource.__init__(self)
self.url = path
def render_GET(self, request):
return redirectTo(self.url.encode('ascii'), request)
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def getChild(self, name, request):
if len(name) == 0:
return self # select ourselves as the child to render
return resource.Resource.getChild(self, name, request)
def respond_with_json(request, code, json_object, send_cors=False,
response_code_message=None, pretty_print=False,
# could alternatively use request.notifyFinish() and flip a flag when
# the Deferred fires, but since the flag is RIGHT THERE it seems like
# a waste.
if request._disconnected:
logger.warn(
"Not sending response to request %s, already disconnected.",
request)
return
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if pretty_print:
json_bytes = encode_pretty_printed_json(json_object) + b"\n"
if canonical_json or synapse.events.USE_FROZEN_DICTS:
# canonicaljson already encodes to bytes
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json_bytes = encode_canonical_json(json_object)
else:
json_bytes = json.dumps(json_object).encode("utf-8")
return respond_with_json_bytes(
request, code, json_bytes,
send_cors=send_cors,
response_code_message=response_code_message,
)
def respond_with_json_bytes(request, code, json_bytes, send_cors=False,
"""Sends encoded JSON in response to the given request.
Args:
request (twisted.web.http.Request): The http request to respond to.
code (int): The HTTP response code.
json_bytes (bytes): The json bytes to use as the response body.
send_cors (bool): Whether to send Cross-Origin Resource Sharing headers
http://www.w3.org/TR/cors/
Returns:
twisted.web.server.NOT_DONE_YET"""
request.setResponseCode(code, message=response_code_message)
request.setHeader(b"Content-Type", b"application/json")
request.setHeader(b"Content-Length", b"%d" % (len(json_bytes),))
request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
set_cors_headers(request)
# todo: we can almost certainly avoid this copy and encode the json straight into
# the bytesIO, but it would involve faffing around with string->bytes wrappers.
bytes_io = BytesIO(json_bytes)
producer = NoRangeStaticProducer(request, bytes_io)
producer.start()
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def set_cors_headers(request):
"""Set the CORs headers so that javascript running in a web browsers can
use this API
Args:
request (twisted.web.http.Request): The http request to add CORs to.
"""
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request.setHeader(b"Access-Control-Allow-Origin", b"*")
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b"Access-Control-Allow-Methods", b"GET, POST, PUT, DELETE, OPTIONS"
)
request.setHeader(
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b"Access-Control-Allow-Headers",
b"Origin, X-Requested-With, Content-Type, Accept, Authorization"
def finish_request(request):
""" Finish writing the response to the request.
Twisted throws a RuntimeException if the connection closed before the
response was written but doesn't provide a convenient or reliable way to
determine if the connection was closed. So we catch and log the RuntimeException
You might think that ``request.notifyFinish`` could be used to tell if the
request was finished. However the deferred it returns won't fire if the
connection was already closed, meaning we'd have to have called the method
right at the start of the request. By the time we want to write the response
it will already be too late.
"""
try:
request.finish()
except RuntimeError as e:
logger.info("Connection disconnected before response was written: %r", e)
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def _request_user_agent_is_curl(request):
user_agents = request.requestHeaders.getRawHeaders(
b"User-Agent", default=[]
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)
for user_agent in user_agents:
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return True
return False