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8 * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
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16 * furnished to do so, under the terms of the COPYING file.
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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 CURLMcode res = CURLM_OK;
47 int timeout;
48
49 global_init(CURL_GLOBAL_ALL);
50
51 multi_init(multiHandle);
52
53 easy_init(curl);
54
55 easy_setopt(curl, CURLOPT_VERBOSE, 1L);
56 easy_setopt(curl, CURLOPT_URL, URL);
57
58 /* Set a DNS server that hopefully will not respond when using c-ares. */
59 if(curl_easy_setopt(curl, CURLOPT_DNS_SERVERS, "0.0.0.0") == CURLE_OK)
60 /* Since we could set the DNS server, presume we are working with a
61 resolver that can be cancelled (i.e. c-ares). Thus,
62 curl_multi_remove_handle() should not block even when the resolver
63 request is outstanding. So, set a request timeout _longer_ than the
64 test hang timeout so we will fail if the handle removal call incorrectly
65 blocks. */
66 timeout = TEST_HANG_TIMEOUT * 2;
67 else {
68 /* If we can't set the DNS server, presume that we are configured to use a
69 resolver that can't be cancelled (i.e. the threaded resolver or the
70 non-threaded blocking resolver). So, we just test that the
71 curl_multi_remove_handle() call does finish well within our test
72 timeout.
73
74 But, it is very unlikely that the resolver request will take any time at
75 all because we haven't been able to configure the resolver to use an
76 non-responsive DNS server. At least we exercise the flow.
77 */
78 fprintf(stderr,
79 "CURLOPT_DNS_SERVERS not supported; "
80 "assuming curl_multi_remove_handle() will block\n");
81 timeout = TEST_HANG_TIMEOUT / 2;
82 }
83
84 /* Setting a timeout on the request should ensure that even if we have to
85 wait for the resolver during curl_multi_remove_handle(), it won't take
86 longer than this, because the resolver request inherits its timeout from
87 this. */
88 easy_setopt(curl, CURLOPT_TIMEOUT_MS, timeout);
89
90 multi_add_handle(multiHandle, curl);
91
92 /* This should move the handle from INIT => CONNECT => WAITRESOLVE. */
93 fprintf(stderr, "curl_multi_perform()...\n");
94 multi_perform(multiHandle, &stillRunning);
95 fprintf(stderr, "curl_multi_perform() succeeded\n");
96
97 /* Start measuring how long it takes to remove the handle. */
98 fprintf(stderr, "curl_multi_remove_handle()...\n");
99 start_test_timing();
100 res = curl_multi_remove_handle(multiHandle, curl);
101 if(res) {
102 fprintf(stderr, "curl_multi_remove_handle() failed, "
103 "with code %d\n", (int)res);
104 goto test_cleanup;
105 }
106 fprintf(stderr, "curl_multi_remove_handle() succeeded\n");
107
108 /* Fail the test if it took too long to remove. This happens after the fact,
109 and says "it seems that it would have run forever", which isn't true, but
110 it's close enough, and simple to do. */
111 abort_on_test_timeout();
112
113test_cleanup:
114 curl_easy_cleanup(curl);
115 curl_multi_cleanup(multiHandle);
116 curl_global_cleanup();
117
118 return (int)res;
119}
120