curl / libcurl / API / URL parsing interface

URL parsing interface overview

Name

libcurl-url - URL interface overview

Description

The URL interface provides functions for parsing and generating URLs.

Include

You still only include <curl/curl.h> in your code.

Create

Create a handle that holds URL info and resources with curl_url:

  CURLU *h = curl_url();

Cleanup

When done with it, clean it up with curl_url_cleanup

  curl_url_cleanup(h);

Duplicate

When you need a copy of a handle, just duplicate it with curl_url_dup:

  CURLU *nh = curl_url_dup(h);

Parsing

By setting a URL to the handle with curl_url_set, the URL is parsed and stored in the handle. If the URL is not syntactically correct it will return an error instead.

  rc = curl_url_set(h, CURLUPART_URL,
                    "https://example.com:449/foo/bar?name=moo", 0);

The zero in the fourth argument is a bitmask for changing specific features.

If successful, this stores the URL in its individual parts within the handle.

Redirect

When a handle already contains info about a URL, setting a relative URL will make it "redirect" to adapt to it.

  rc = curl_url_set(h, CURLUPART_URL, "../test?another", 0);

Get url

The CURLU handle represents a URL and you can easily extract that with curl_url_get:

  char *url;
  rc = curl_url_get(h, CURLUPART_URL, &url, 0);
  curl_free(url);

The zero in the fourth argument is a bitmask for changing specific features.

Get parts

When a URL has been parsed or parts have been set, you can extract those pieces from the handle at any time.

  rc = curl_url_get(h, CURLUPART_HOST, &host, 0);
  rc = curl_url_get(h, CURLUPART_SCHEME, &scheme, 0);
  rc = curl_url_get(h, CURLUPART_USER, &user, 0);
  rc = curl_url_get(h, CURLUPART_PASSWORD, &password, 0);
  rc = curl_url_get(h, CURLUPART_PORT, &port, 0);
  rc = curl_url_get(h, CURLUPART_PATH, &path, 0);
  rc = curl_url_get(h, CURLUPART_QUERY, &query, 0);
  rc = curl_url_get(h, CURLUPART_FRAGMENT, &fragment, 0);

Extracted parts are not URL decoded unless the user also asks for it with the CURLU_URLDECODE flag set in the fourth bitmask argument.

Remember to free the returned string with curl_free when you are done with it!

Set parts

A user set individual URL parts, either after having parsed a full URL or instead of parsing such.

  rc = curl_url_set(urlp, CURLUPART_HOST, "www.example.com", 0);
  rc = curl_url_set(urlp, CURLUPART_SCHEME, "https", 0);
  rc = curl_url_set(urlp, CURLUPART_USER, "john", 0);
  rc = curl_url_set(urlp, CURLUPART_PASSWORD, "doe", 0);
  rc = curl_url_set(urlp, CURLUPART_PORT, "443", 0);
  rc = curl_url_set(urlp, CURLUPART_PATH, "/index.html", 0);
  rc = curl_url_set(urlp, CURLUPART_QUERY, "name=john", 0);
  rc = curl_url_set(urlp, CURLUPART_FRAGMENT, "anchor", 0);

Set parts are not URL encoded unless the user asks for it with the CURLU_URLENCODE flag.

Curlu_appendquery

An application can append a string to the right end of the query part with the CURLU_APPENDQUERY flag to curl_url_set.

Imagine a handle that holds the URL "https://example.com/?shoes=2". An application can then add the string "hat=1" to the query part like this:

  rc = curl_url_set(urlp, CURLUPART_QUERY, "hat=1", CURLU_APPENDQUERY);

It will even notice the lack of an ampersand (&) separator so it will inject one too, and the handle's full URL will then equal "https://example.com/?shoes=2&hat=1".

The appended string can of course also get URL encoded on add, and if asked to URL encode, the encoding process will skip the '=' character. For example, append "candy=N&N" to what we already have, and URL encode it to deal with the ampersand in the data:

  rc = curl_url_set(urlp, CURLUPART_QUERY, "candy=N&N",
                    CURLU_APPENDQUERY | CURLU_URLENCODE);

Now the URL looks like

  https://example.com/?shoes=2&hat=1&candy=N%26N

Availability

The URL API was introduced in libcurl 7.62.0.

See also

curl_url(3), curl_url_cleanup(3), curl_url_get(3), curl_url_dup(3), curl_url_set(3), curl_url_strerror(3), CURLOPT_URL(3)

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