1CURLOPT_HAPPY_EYEBALLS_TIMEOcUuTr_lM_Se(a3s)y_setoptCUoRpLtOiPoTn_sHAPPY_EYEBALLS_TIMEOUT_MS(3)
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6 CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS - head start for ipv6 for happy eye‐
7 balls
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10 #include <curl/curl.h>
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12 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HAPPY_EYEBALLS_TIME‐
13 OUT_MS, long timeout);
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16 Happy eyeballs is an algorithm that attempts to connect to both IPv4
17 and IPv6 addresses for dual-stack hosts, preferring IPv6 first for
18 timeout milliseconds. If the IPv6 address cannot be connected to within
19 that time then a connection attempt is made to the IPv4 address in par‐
20 allel. The first connection to be established is the one that is used.
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22 The range of suggested useful values for timeout is limited. Happy Eye‐
23 balls RFC 6555 says "It is RECOMMENDED that connection attempts be
24 paced 150-250 ms apart to balance human factors against network load."
25 libcurl currently defaults to 200 ms. Firefox and Chrome currently
26 default to 300 ms.
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29 CURL_HET_DEFAULT (currently defined as 200L)
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32 CURL *curl = curl_easy_init();
33 if(curl) {
34 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
35 curl_easy_setopt(curl, CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS, 300L);
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37 curl_easy_perform(curl);
38
39 /* always cleanup */
40 curl_easy_cleanup(curl);
41 }
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44 Added in 7.59.0
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47 Returns CURLE_OK
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51libcurl 7.71.1 March 23, 2C0U2R0LOPT_HAPPY_EYEBALLS_TIMEOUT_MS(3)