A long parameter set to 1 tells the library to follow any Location: header
that the server sends as part of a HTTP header in a 3xx response. The
Location: header can specify a relative or an absolute URL to follow.
libcurl will issue another request for the new URL and follow new Location:
headers all the way until no more such headers are returned.
CURLOPT_MAXREDIRS(3) can be used to limit the number of redirects
libcurl will follow.
libcurl limits what protocols it automatically follows to. The accepted
protocols are set with CURLOPT_REDIR_PROTOCOLS(3). By default libcurl
will allow all protocols on redirect except those disabled for security
reasons: Since 7.19.4 FILE and SCP are disabled, and since 7.40.0 SMB and SMBS
are also disabled.
When following a Location:, the 3xx response code that redirected it also
dictates which request method it will use in the subsequent request: For 301,
302 and 303 responses libcurl will switch method to GET unless
CURLOPT_POSTREDIR(3) instructs libcurl otherwise. All other 3xx codes
will make libcurl send the same method again.
For users who think the existing location following is too naive, too simple
or just lacks features, it is very easy to instead implement your own redirect
follow logic with the use of curl_easy_getinfo(3)s
CURLINFO_REDIRECT_URL(3) option instead of using
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
/* example.com is redirected, so we tell libcurl to follow redirection */
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);