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* Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
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* This software is licensed as described in the file COPYING, which
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CURLINFO_RETRY_AFTER - returns the Retry-After retry delay #include <curl/curl.h> CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_RETRY_AFTER, curl_off_t *retry); Pass a pointer to a curl_off_t variable to receive the number of seconds the HTTP server suggests the client should wait until the next request is issued. The information from the "Retry-After:" header. While the HTTP header might contain a fixed date string, the CURLINFO_RETRY_AFTER(3) will always return number of seconds to wait - or zero if there was no header or the header couldn't be parsed. Returns zero delay if there was no header. HTTP(S)

CURL *curl = curl_easy_init();
if(curl) {
 CURLcode res;
 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 res = curl_easy_perform(curl);
 if(res == CURLE_OK) {
 curl_off_t wait = 0;
 curl_easy_getinfo(curl, CURLINFO_RETRY_AFTER, &wait);
 if(wait)
 printf("Wait for %" CURL_FORMAT_CURL_OFF_T " seconds\\n", wait);
 }
 curl_easy_cleanup(curl);
}

Added in curl 7.66.0 Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. CURLOPT_STDERR "(3), " CURLOPT_HEADERFUNCTION "(3), "