curl_url_get(3) libcurl curl_url_get(3)

curl_url_get - extract a part from a URL

#include <curl/curl.h>
CURLUcode curl_url_get(const CURLU *url,
                       CURLUPart part,
                       char **content,
                       unsigned int flags);

Given a url handle of a URL object, this function extracts an individual piece or the full URL from it.

The part argument specifies which part to extract (see list below) and content points to a 'char *' to get updated to point to a newly allocated string with the contents.

The flags argument is a bitmask with individual features.

The returned content pointer must be freed with curl_free(3) after use.

The flags argument is zero, one or more bits set in a bitmask.

If the handle has no port stored, this option makes curl_url_get(3) return the default port for the used scheme.
If the handle has no scheme stored, this option makes curl_url_get(3) return the default scheme instead of error.
Instructs curl_url_get(3) to not return a port number if it matches the default port for the scheme.
Asks curl_url_get(3) to URL decode the contents before returning it. It does not decode the scheme, the port number or the full URL.

The query component also gets plus-to-space conversion as a bonus when this bit is set.

Note that this URL decoding is charset unaware and you get a zero terminated string back with data that could be intended for a particular encoding.

If there are byte values lower than 32 in the decoded string, the get operation returns an error instead.

If set, curl_url_get(3) URL encodes the host name part when a full URL is retrieved. If not set (default), libcurl returns the URL with the host name "raw" to support IDN names to appear as-is. IDN host names are typically using non-ASCII bytes that otherwise gets percent-encoded.

Note that even when not asking for URL encoding, the '%' (byte 37) is URL encoded to make sure the host name remains valid.

If set and CURLU_URLENCODE is not set, and asked to retrieve the CURLUPART_HOST or CURLUPART_URL parts, libcurl returns the host name in its punycode version if it contains any non-ASCII octets (and is an IDN name).

If libcurl is built without IDN capabilities, using this bit makes curl_url_get(3) return CURLUE_LACKS_IDN if the host name contains anything outside the ASCII range.

(Added in curl 7.88.0)

If set and asked to retrieve the CURLUPART_HOST or CURLUPART_URL parts, libcurl returns the host name in its IDN (International Domain Name) UTF-8 version if it otherwise is a punycode version. If the punycode name cannot be converted to IDN correctly, libcurl returns CURLUE_BAD_HOSTNAME.

If libcurl is built without IDN capabilities, using this bit makes curl_url_get(3) return CURLUE_LACKS_IDN if the host name is using punycode.

(Added in curl 8.3.0)

When asked to return the full URL, curl_url_get(3) returns a normalized and possibly cleaned up version using all available URL parts.

We advise using the CURLU_PUNYCODE option to get the URL as "normalized" as possible since IDN allows host names to be written in many different ways that still end up the same punycode version.

Scheme cannot be URL decoded on get.
The options field is an optional field that might follow the password in the userinfo part. It is only recognized/used when parsing URLs for the following schemes: pop3, smtp and imap. The URL API still allows users to set and get this field independently of scheme when not parsing full URLs.
The host name. If it is an IPv6 numeric address, the zone id is not part of it but is provided separately in CURLUPART_ZONEID. IPv6 numerical addresses are returned within brackets ([]).

IPv6 names are normalized when set, which should make them as short as possible while maintaining correct syntax.

If the host name is a numeric IPv6 address, this field might also be set.
A port cannot be URL decoded on get. This number is returned in a string just like all other parts. That string is guaranteed to hold a valid port number in ASCII using base 10.
The part is always at least a slash ('/') even if no path was supplied in the URL. A URL path always starts with a slash.
The initial question mark that denotes the beginning of the query part is a delimiter only. It is not part of the query contents.

A not-present query returns part set to NULL. A zero-length query returns part as a zero-length string.

The query part gets pluses converted to space when asked to URL decode on get with the CURLU_URLDECODE bit.

The initial hash sign that denotes the beginning of the fragment is a delimiter only. It is not part of the fragment contents.

int main(void)
{
  CURLUcode rc;
  CURLU *url = curl_url();
  rc = curl_url_set(url, CURLUPART_URL, "https://example.com", 0);
  if(!rc) {
    char *scheme;
    rc = curl_url_get(url, CURLUPART_SCHEME, &scheme, 0);
    if(!rc) {
      printf("the scheme is %s\n", scheme);
      curl_free(scheme);
    }
    curl_url_cleanup(url);
  }
}

Added in 7.62.0. CURLUPART_ZONEID was added in 7.65.0.

Returns a CURLUcode error value, which is CURLUE_OK (0) if everything went fine. See the libcurl-errors(3) man page for the full list with descriptions.

If this function returns an error, no URL part is returned.

curl_url(3), curl_url_cleanup(3), curl_url_dup(3), curl_url_set(3), curl_url_strerror(3), CURLOPT_CURLU(3)

December 4, 2023 libcurl 8.5.0