CURLOPT_RANGE − set byte range to request
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RANGE, char *range);
Pass a char * as parameter, which should contain the specified range you want to retrieve. It should be in the format "X-Y", where either X or Y may be left out and X and Y are byte indexes.
HTTP transfers also support several intervals, separated with commas as in "X-Y,N-M". Using this kind of multiple intervals will cause the HTTP server to send the response document in pieces (using standard MIME separation techniques). Unfortunately, the HTTP standard (RFC 7233 section 3.1) allows servers to ignore range requests so even when you set CURLOPT_RANGE(3) for a request, you may end up getting the full response sent back.
For RTSP, the formatting of a range should follow RFC2326 Section 12.29. For RTSP, byte ranges are not permitted. Instead, ranges should be given in npt, utc, or smpte formats.
For HTTP PUT uploads this option should not be used, since it may conflict with other options. If you need to upload arbitrary parts of a file (like for Amazon’s web services) support is limited. We suggest set resume position using CURLOPT_RESUME_FROM(3), set end (resume+size) position using CURLOPT_INFILESIZE(3) and seek to the resume position before initiating the transfer for each part. For more information refer to https://curl.haxx.se/mail/lib-2019-05/0012.html
Pass a NULL to this option to disable the use of ranges.
The application does not have to keep the string around after setting this option.
HTTP, FTP, FILE, RTSP and SFTP.
CURL *curl =
curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
/* get the
first 200 bytes */
curl_easy_setopt(curl, CURLOPT_RANGE, "0-199");
/* Perform the
FILE since 7.18.0, RTSP since 7.20.0
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient heap space.