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CURLOPT_URL(3) curl_easy_setopt options CURLOPT_URL(3)
CURLOPT_URL - provide the URL to use in the request
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_URL, char *URL);
Pass in a pointer to the URL to work with. The parameter should be a
char * to a null-terminated string which must be URL-encoded in the
For a greater explanation of the format please see RFC3986.
libcurl doesn't validate the syntax or use this variable until the
transfer is issued. Even if you set a crazy value here,
curl_easy_setopt(3) will still return CURLE_OK.
If the given URL is missing a scheme name (such as "http://" or
"ftp://" etc) then libcurl will make a guess based on the host. If the
outermost sub-domain name matches DICT, FTP, IMAP, LDAP, POP3 or SMTP
then that protocol will be used, otherwise HTTP will be used. Since
7.45.0 guessing can be disabled by setting a default protocol, see
CURLOPT_DEFAULT_PROTOCOL(3) for details.
Should the protocol, either that specified by the scheme or deduced by
libcurl from the host name, not be supported by libcurl then
CURLE_UNSUPPORTED_PROTOCOL will be returned from either the
curl_easy_perform(3) or curl_multi_perform(3) functions when you call
them. Use curl_version_info(3) for detailed information of which
protocols are supported by the build of libcurl you are using.
CURLOPT_PROTOCOLS(3) can be used to limit what protocols libcurl will
use for this transfer, independent of what libcurl has been compiled to
support. That may be useful if you accept the URL from an external
source and want to limit the accessibility.
The CURLOPT_URL(3) string will be ignored if CURLOPT_CURLU(3) is set.
CURLOPT_URL(3) or CURLOPT_CURLU(3) must be set before a transfer is
The application does not have to keep the string around after setting
The string pointed to in the CURLOPT_URL(3) argument is generally
expected to be a sequence of characters using an ASCII compatible
If libcurl is built with IDN support, the server name part of the URL
can use an "international name" by using the current encoding
(according to locale) or UTF-8 (when winidn is used; or a Windows
Unicode build using libidn2).
If libcurl is built without IDN support, the server name is used
exactly as specified when passed to the name resolver functions.
There is no default URL. If this option isn't set, no transfer can be
Applications may at times find it convenient to allow users to specify
URLs for various purposes and that string would then end up fed to this
Getting a URL from an external untrusted party will bring reasons for
several security concerns:
If you have an application that runs as or in a server application,
getting an unfiltered URL can easily trick your application to access a
local resource instead of a remote. Protecting yourself against
localhost accesses is very hard when accepting user provided URLs.
Such custom URLs can also access other ports than you planned as port
numbers are part of the regular URL format. The combination of a local
host and a custom port number can allow external users to play tricks
with your local services.
Accepting external URLs may also use other protocols than http:// or
other common ones. Restrict what accept with CURLOPT_PROTOCOLS(3).
User provided URLs can also be made to point to sites that redirect
further on (possibly to other protocols too). Consider your
CURLOPT_FOLLOWLOCATION(3) and CURLOPT_REDIR_PROTOCOLS(3) settings.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
POP3 and SMTP were added in 7.31.0
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was
insufficient heap space.
Note that curl_easy_setopt(3) won't actually parse the given string so
given a bad URL, it will not be detected until curl_easy_perform(3) or
similar is called.
CURLOPT_VERBOSE(3), CURLOPT_PROTOCOLS(3), CURLOPT_FORBID_REUSE(3),
CURLINFO_REDIRECT_URL(3), CURLOPT_PATH_AS_IS(3), CURLOPT_CURLU(3),
libcurl 7.78.0 June 15, 2021 CURLOPT_URL(3)