Treat an invalid .well-known the same as an absent one

... basically, carry on and fall back to SRV etc.
This commit is contained in:
Richard van der Hoff 2019-02-01 11:33:48 +00:00
parent 582786fbf2
commit 8a21b03fba
3 changed files with 79 additions and 32 deletions

1
changelog.d/4544.misc Normal file
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@ -0,0 +1 @@
Treat an invalid .well-known file the same as an absent one

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@ -47,9 +47,6 @@ WELL_KNOWN_INVALID_CACHE_PERIOD = 1 * 3600
# cap for .well-known cache period
WELL_KNOWN_MAX_CACHE_PERIOD = 48 * 3600
# magic value to mark an invalid well-known
INVALID_WELL_KNOWN = object()
logger = logging.getLogger(__name__)
well_known_cache = TTLCache('well-known')
@ -108,8 +105,7 @@ class MatrixFederationAgent(object):
# our cache of .well-known lookup results, mapping from server name
# to delegated name. The values can be:
# `bytes`: a valid server-name
# `None`: there is no .well-known here
# INVALID_WELL_KNWOWN: the .well-known here is invalid
# `None`: there is no (valid) .well-known here
self._well_known_cache = _well_known_cache
@defer.inlineCallbacks
@ -302,9 +298,6 @@ class MatrixFederationAgent(object):
if cache_period > 0:
self._well_known_cache.set(server_name, result, cache_period)
if result == INVALID_WELL_KNOWN:
raise Exception("invalid .well-known on this server")
defer.returnValue(result)
@defer.inlineCallbacks
@ -331,6 +324,13 @@ class MatrixFederationAgent(object):
body = yield make_deferred_yieldable(readBody(response))
if response.code != 200:
raise Exception("Non-200 response %s" % (response.code, ))
parsed_body = json.loads(body.decode('utf-8'))
logger.info("Response from .well-known: %s", parsed_body)
if not isinstance(parsed_body, dict):
raise Exception("not a dict")
if "m.server" not in parsed_body:
raise Exception("Missing key 'm.server'")
except Exception as e:
logger.info("Error fetching %s: %s", uri_str, e)
@ -340,19 +340,6 @@ class MatrixFederationAgent(object):
cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER)
defer.returnValue((None, cache_period))
try:
parsed_body = json.loads(body.decode('utf-8'))
logger.info("Response from .well-known: %s", parsed_body)
if not isinstance(parsed_body, dict):
raise Exception("not a dict")
if "m.server" not in parsed_body:
raise Exception("Missing key 'm.server'")
except Exception as e:
logger.info("invalid .well-known response from %s: %s", uri_str, e)
cache_period = WELL_KNOWN_INVALID_CACHE_PERIOD
cache_period += random.uniform(0, WELL_KNOWN_DEFAULT_CACHE_PERIOD_JITTER)
defer.returnValue((INVALID_WELL_KNOWN, cache_period))
result = parsed_body["m.server"].encode("ascii")
cache_period = _cache_period_from_headers(

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@ -124,7 +124,7 @@ class MatrixFederationAgentTests(TestCase):
_check_logcontext(context)
def _handle_well_known_connection(
self, client_factory, expected_sni, target_server, response_headers={},
self, client_factory, expected_sni, content, response_headers={},
):
"""Handle an outgoing HTTPs connection: wire it up to a server, check that the
request is for a .well-known, and send the response.
@ -132,8 +132,7 @@ class MatrixFederationAgentTests(TestCase):
Args:
client_factory (IProtocolFactory): outgoing connection
expected_sni (bytes): SNI that we expect the outgoing connection to send
target_server (bytes): target server that we should redirect to in the
.well-known response.
content (bytes): content to send back as the .well-known
Returns:
HTTPChannel: server impl
"""
@ -145,10 +144,10 @@ class MatrixFederationAgentTests(TestCase):
# check the .well-known request and send a response
self.assertEqual(len(well_known_server.requests), 1)
request = well_known_server.requests[0]
self._send_well_known_response(request, target_server, headers=response_headers)
self._send_well_known_response(request, content, headers=response_headers)
return well_known_server
def _send_well_known_response(self, request, target_server, headers={}):
def _send_well_known_response(self, request, content, headers={}):
"""Check that an incoming request looks like a valid .well-known request, and
send back the response.
"""
@ -161,7 +160,7 @@ class MatrixFederationAgentTests(TestCase):
# send back a response
for k, v in headers.items():
request.setHeader(k, v)
request.write(b'{ "m.server": "%s" }' % (target_server,))
request.write(content)
request.finish()
self.reactor.pump((0.1, ))
@ -407,7 +406,7 @@ class MatrixFederationAgentTests(TestCase):
self.successResultOf(test_d)
def test_get_well_known(self):
"""Test the behaviour when the .well-known redirects elsewhere
"""Test the behaviour when the .well-known delegates elsewhere
"""
self.mock_resolver.resolve_service.side_effect = lambda _: []
@ -427,7 +426,8 @@ class MatrixFederationAgentTests(TestCase):
self.assertEqual(port, 443)
self._handle_well_known_connection(
client_factory, expected_sni=b"testserv", target_server=b"target-server",
client_factory, expected_sni=b"testserv",
content=b'{ "m.server": "target-server" }',
)
# there should be a SRV lookup
@ -560,6 +560,64 @@ class MatrixFederationAgentTests(TestCase):
self.well_known_cache.expire()
self.assertNotIn(b"testserv", self.well_known_cache)
def test_get_invalid_well_known(self):
"""
Test the behaviour when the server name has an *invalid* well-known (and no SRV)
"""
self.mock_resolver.resolve_service.side_effect = lambda _: []
self.reactor.lookups["testserv"] = "1.2.3.4"
test_d = self._make_get_request(b"matrix://testserv/foo/bar")
# Nothing happened yet
self.assertNoResult(test_d)
# No SRV record lookup yet
self.mock_resolver.resolve_service.assert_not_called()
# there should be an attempt to connect on port 443 for the .well-known
clients = self.reactor.tcpClients
self.assertEqual(len(clients), 1)
(host, port, client_factory, _timeout, _bindAddress) = clients.pop()
self.assertEqual(host, '1.2.3.4')
self.assertEqual(port, 443)
self._handle_well_known_connection(
client_factory, expected_sni=b"testserv", content=b'NOT JSON',
)
# now there should be a SRV lookup
self.mock_resolver.resolve_service.assert_called_once_with(
b"_matrix._tcp.testserv",
)
# we should fall back to a direct connection
self.assertEqual(len(clients), 1)
(host, port, client_factory, _timeout, _bindAddress) = clients.pop()
self.assertEqual(host, '1.2.3.4')
self.assertEqual(port, 8448)
# make a test server, and wire up the client
http_server = self._make_connection(
client_factory,
expected_sni=b'testserv',
)
self.assertEqual(len(http_server.requests), 1)
request = http_server.requests[0]
self.assertEqual(request.method, b'GET')
self.assertEqual(request.path, b'/foo/bar')
self.assertEqual(
request.requestHeaders.getRawHeaders(b'host'),
[b'testserv'],
)
# finish the request
request.finish()
self.reactor.pump((0.1,))
self.successResultOf(test_d)
def test_get_hostname_srv(self):
"""
Test the behaviour when there is a single SRV record
@ -630,7 +688,8 @@ class MatrixFederationAgentTests(TestCase):
]
self._handle_well_known_connection(
client_factory, expected_sni=b"testserv", target_server=b"target-server",
client_factory, expected_sni=b"testserv",
content=b'{ "m.server": "target-server" }',
)
# there should be a SRV lookup
@ -797,7 +856,7 @@ class MatrixFederationAgentTests(TestCase):
client_factory,
expected_sni=b"testserv",
response_headers={b'Cache-Control': b'max-age=10'},
target_server=b"target-server",
content=b'{ "m.server": "target-server" }',
)
r = self.successResultOf(fetch_d)
@ -825,7 +884,7 @@ class MatrixFederationAgentTests(TestCase):
self._handle_well_known_connection(
client_factory,
expected_sni=b"testserv",
target_server=b"other-server",
content=b'{ "m.server": "other-server" }',
)
r = self.successResultOf(fetch_d)