1/***************************************************************************
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7 *
8 * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
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12 * are also available at https://curl.se/docs/copyright.html.
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15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
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18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
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21 ***************************************************************************/
22/*
23 * See https://github.com/curl/curl/issues/3371
24 *
25 * This test case checks whether curl_multi_remove_handle() cancels
26 * asynchronous DNS resolvers without blocking where possible. Obviously, it
27 * only tests whichever resolver cURL is actually built with.
28 */
29
30/* We're willing to wait a very generous two seconds for the removal. This is
31 as low as we can go while still easily supporting SIGALRM timing for the
32 non-threaded blocking resolver. It doesn't matter that much because when
33 the test passes, we never wait this long. */
34#define TEST_HANG_TIMEOUT 2 * 1000
35
36#include "test.h"
37#include "testutil.h"
38
39#include <sys/stat.h>
40
41int test(char *URL)
42{
43 int stillRunning;
44 CURLM *multiHandle = NULL;
45 CURL *curl = NULL;
46 CURLcode res = CURLE_OK;
47 CURLMcode mres;
48 int timeout;
49
50 global_init(CURL_GLOBAL_ALL);
51
52 multi_init(multiHandle);
53
54 easy_init(curl);
55
56 easy_setopt(curl, CURLOPT_VERBOSE, 1L);
57 easy_setopt(curl, CURLOPT_URL, URL);
58
59 /* Set a DNS server that hopefully will not respond when using c-ares. */
60 if(curl_easy_setopt(curl, CURLOPT_DNS_SERVERS, "0.0.0.0") == CURLE_OK)
61 /* Since we could set the DNS server, presume we are working with a
62 resolver that can be cancelled (i.e. c-ares). Thus,
63 curl_multi_remove_handle() should not block even when the resolver
64 request is outstanding. So, set a request timeout _longer_ than the
65 test hang timeout so we will fail if the handle removal call incorrectly
66 blocks. */
67 timeout = TEST_HANG_TIMEOUT * 2;
68 else {
69 /* If we can't set the DNS server, presume that we are configured to use a
70 resolver that can't be cancelled (i.e. the threaded resolver or the
71 non-threaded blocking resolver). So, we just test that the
72 curl_multi_remove_handle() call does finish well within our test
73 timeout.
74
75 But, it is very unlikely that the resolver request will take any time at
76 all because we haven't been able to configure the resolver to use an
77 non-responsive DNS server. At least we exercise the flow.
78 */
79 fprintf(stderr,
80 "CURLOPT_DNS_SERVERS not supported; "
81 "assuming curl_multi_remove_handle() will block\n");
82 timeout = TEST_HANG_TIMEOUT / 2;
83 }
84
85 /* Setting a timeout on the request should ensure that even if we have to
86 wait for the resolver during curl_multi_remove_handle(), it won't take
87 longer than this, because the resolver request inherits its timeout from
88 this. */
89 easy_setopt(curl, CURLOPT_TIMEOUT_MS, timeout);
90
91 multi_add_handle(multiHandle, curl);
92
93 /* This should move the handle from INIT => CONNECT => WAITRESOLVE. */
94 fprintf(stderr, "curl_multi_perform()...\n");
95 multi_perform(multiHandle, &stillRunning);
96 fprintf(stderr, "curl_multi_perform() succeeded\n");
97
98 /* Start measuring how long it takes to remove the handle. */
99 fprintf(stderr, "curl_multi_remove_handle()...\n");
100 start_test_timing();
101 mres = curl_multi_remove_handle(multiHandle, curl);
102 if(mres) {
103 fprintf(stderr, "curl_multi_remove_handle() failed, "
104 "with code %d\n", (int)res);
105 res = TEST_ERR_MULTI;
106 goto test_cleanup;
107 }
108 fprintf(stderr, "curl_multi_remove_handle() succeeded\n");
109
110 /* Fail the test if it took too long to remove. This happens after the fact,
111 and says "it seems that it would have run forever", which isn't true, but
112 it's close enough, and simple to do. */
113 abort_on_test_timeout();
114
115test_cleanup:
116 curl_easy_cleanup(curl);
117 curl_multi_cleanup(multiHandle);
118 curl_global_cleanup();
119
120 return (int)res;
121}
122