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serrislewSerris Lew
serrislew
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Serris Lew
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Serve stale content when DNS lookup fails (#8484)
* serve stale when dns lookups fails * updated max-age in autest to run shorter Co-authored-by: Serris Lew <lserris@apple.com>
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+144
-10
lines changed

3 files changed

+144
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lines changed

‎proxy/http/HttpTransact.cc‎

Lines changed: 8 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -1942,6 +1942,13 @@ HttpTransact::OSDNSLookup(State *s)
19421942
} else {
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TxnDebug("http_seq", "[HttpTransact::OSDNSLookup] DNS Lookup unsuccessful");
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// Even with unsuccessful DNS lookup, return stale object from cache if applicable
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if (is_cache_hit(s->cache_lookup_result) && is_stale_cache_response_returnable(s)) {
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s->source = SOURCE_CACHE;
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TxnDebug("http_trans", "[hscno] serving stale doc to client");
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build_response_from_cache(s, HTTP_WARNING_CODE_REVALIDATION_FAILED);
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return;
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}
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// output the DNS failure error message
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SET_VIA_STRING(VIA_DETAIL_TUNNEL, VIA_DETAIL_TUNNEL_NO_FORWARD);
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// Set to internal server error so later logging will pick up SQUID_LOG_ERR_DNS_FAIL
@@ -2642,16 +2649,7 @@ HttpTransact::HandleCacheOpenReadHitFreshness(State *s)
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SET_VIA_STRING(VIA_CACHE_RESULT, VIA_IN_CACHE_STALE);
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}
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2645-
if (!s->force_dns) { // If DNS is not performed before
2646-
if (need_to_revalidate(s)) {
2647-
TRANSACT_RETURN(SM_ACTION_API_CACHE_LOOKUP_COMPLETE,
2648-
CallOSDNSLookup); // content needs to be revalidated and we did not perform a dns ....calling DNS lookup
2649-
} else { // document can be served can cache
2650-
TRANSACT_RETURN(SM_ACTION_API_CACHE_LOOKUP_COMPLETE, HttpTransact::HandleCacheOpenReadHit);
2651-
}
2652-
} else { // we have done dns . Its up to HandleCacheOpenReadHit to decide to go OS or serve from cache
2653-
TRANSACT_RETURN(SM_ACTION_API_CACHE_LOOKUP_COMPLETE, HttpTransact::HandleCacheOpenReadHit);
2654-
}
2652+
TRANSACT_RETURN(SM_ACTION_API_CACHE_LOOKUP_COMPLETE, HttpTransact::HandleCacheOpenReadHit);
26552653
}
26562654

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///////////////////////////////////////////////////////////////////////////////

‎tests/gold_tests/proxy_protocol/gold/serve_stale_dns_fail.gold‎

Lines changed: 57 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,57 @@
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``
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> GET / HTTP/1.1
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> Host: ``
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> User-Agent: curl/``
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> Accept: */*
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``
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< HTTP/1.1 200 OK
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< Server: ATS``
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< Accept-Ranges: bytes
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< Content-Length: 6
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< Cache-Control: public, max-age=5
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< Expires: ``
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< Age: ``
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< Date: ``
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< Connection: keep-alive
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``
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> GET / HTTP/1.1
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> Host: ``
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> User-Agent: curl/``
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> Accept: */*
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``
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< HTTP/1.1 500 Cannot find server.
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< Date: ``
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< Server: ATS``
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< Cache-Control: no-store
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< Content-Type: ``
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< Content-Language: ``
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< Content-Length: ``
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< Connection: keep-alive
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``
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> GET / HTTP/1.1
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> Host: ``
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> User-Agent: curl/``
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> Accept: */*
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``
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< HTTP/1.1 200 OK
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< Server: ATS``
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< Accept-Ranges: bytes
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< Content-Length: 6
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< Cache-Control: public, max-age=5
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< Age: ``
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< Date: ``
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< Connection: keep-alive
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``
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> GET / HTTP/1.1
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> Host: ``
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> User-Agent: curl/``
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> Accept: */*
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``
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< HTTP/1.1 500 Cannot find server.
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< Date: ``
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< Server: ATS``
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< Cache-Control: no-store
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< Content-Type: ``
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< Content-Language: ``
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< Content-Length: ``
57+
``

‎tests/gold_tests/proxy_protocol/proxy_serve_stale_dns_fail.test.py‎

Lines changed: 79 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,79 @@
1+
'''
2+
Test proxy serving stale content when DNS lookup fails
3+
'''
4+
# Licensed to the Apache Software Foundation (ASF) under one
5+
# or more contributor license agreements. See the NOTICE file
6+
# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
8+
# to you under the Apache License, Version 2.0 (the
9+
# "License"); you may not use this file except in compliance
10+
# with the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
13+
#
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# Unless required by applicable law or agreed to in writing, software
15+
# distributed under the License is distributed on an "AS IS" BASIS,
16+
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17+
# See the License for the specific language governing permissions and
18+
# limitations under the License.
19+
20+
Test.ContinueOnFail = True
21+
# Set up hierarchical caching processes
22+
ts_child = Test.MakeATSProcess("ts_child")
23+
ts_parent = Test.MakeATSProcess("ts_parent")
24+
server_name = "http://unknown.domain.com/"
25+
26+
Test.testName = "STALE"
27+
28+
# Config child proxy to route to parent proxy
29+
ts_child.Disk.records_config.update({
30+
'proxy.config.url_remap.pristine_host_hdr': 1,
31+
'proxy.config.http.cache.max_stale_age': 10,
32+
'proxy.config.http.parent_proxy.self_detect': 0,
33+
})
34+
ts_child.Disk.parent_config.AddLine(
35+
f'dest_domain=. parent=localhost:{ts_parent.Variables.port} round_robin=consistent_hash go_direct=false'
36+
)
37+
ts_child.Disk.remap_config.AddLine(
38+
f'map http://localhost:{ts_child.Variables.port} {server_name}'
39+
)
40+
41+
# Configure parent proxy
42+
ts_parent.Disk.records_config.update({
43+
'proxy.config.url_remap.pristine_host_hdr': 1,
44+
'proxy.config.http.cache.max_stale_age': 10,
45+
})
46+
ts_parent.Disk.remap_config.AddLine(
47+
f'map http://localhost:{ts_parent.Variables.port} {server_name}'
48+
)
49+
ts_parent.Disk.remap_config.AddLine(
50+
f'map {server_name} {server_name}'
51+
)
52+
53+
# Object to push to proxies
54+
stale_5 = "HTTP/1.1 200 OK\nServer: ATS/10.0.0\nAccept-Ranges: bytes\nContent-Length: 6\nCache-Control: public, max-age=5\n\nCACHED"
55+
stale_10 = "HTTP/1.1 200 OK\nServer: ATS/10.0.0\nAccept-Ranges: bytes\nContent-Length: 6\nCache-Control: public, max-age=10\n\nCACHED"
56+
57+
58+
# Testing scenarios
59+
child_curl_request = (
60+
# Test child serving stale with failed DNS OS lookup
61+
f'curl -X PUSH -d "{stale_5}" "http://localhost:{ts_child.Variables.port}";'
62+
f'curl -X PUSH -d "{stale_10}" "http://localhost:{ts_parent.Variables.port}";'
63+
f'sleep 7; curl -s -v http://localhost:{ts_child.Variables.port};'
64+
f'sleep 15; curl -s -v http://localhost:{ts_child.Variables.port};'
65+
# Test parent serving stale with failed DNS OS lookup
66+
f'curl -X PUSH -d "{stale_5}" "http://localhost:{ts_parent.Variables.port}";'
67+
f'sleep 7; curl -s -v http://localhost:{ts_parent.Variables.port};'
68+
f'sleep 15; curl -s -v http://localhost:{ts_parent.Variables.port};'
69+
)
70+
71+
# Test case for when parent server is down but child proxy can serve cache object
72+
tr = Test.AddTestRun()
73+
tr.Processes.Default.Command = child_curl_request
74+
tr.Processes.Default.ReturnCode = 0
75+
tr.Processes.Default.StartBefore(ts_child)
76+
tr.Processes.Default.StartBefore(ts_parent)
77+
tr.Processes.Default.Streams.stderr = "gold/serve_stale_dns_fail.gold"
78+
tr.StillRunningAfter = ts_child
79+
tr.StillRunningAfter = ts_parent

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