CURLOPT_URL(3) curl_easy_setopt options CURLOPT_URL(3)
NAME
CURLOPT_URL - URL for this transfer
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_URL, char *URL);
DESCRIPTION
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
following format:
scheme://host:port/path
For a greater explanation of the format please see RFC3986.
libcurl does not validate the syntax or use this variable until the
transfer is issued. Even if you set a crazy value here, curl_easy_se-
topt(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 CUR-
LOPT_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_UN-
SUPPORTED_PROTOCOL will be returned from either the curl_easy_per-
form(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
started.
The application does not have to keep the string around after setting
this option.
ENCODING
The string pointed to in the CURLOPT_URL(3) argument is generally ex-
pected to be a sequence of characters using an ASCII compatible encod-
ing.
If libcurl is built with IDN support, the server name part of the URL
can use an "international name" by using the current encoding (accord-
ing 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 ex-
actly as specified when passed to the name resolver functions.
DEFAULT
There is no default URL. If this option is not set, no transfer can be
performed.
SECURITY CONCERNS
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
option.
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 local-
host accesses is 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 CUR-
LOPT_FOLLOWLOCATION(3) and CURLOPT_REDIR_PROTOCOLS(3) settings.
PROTOCOLS
All
EXAMPLE
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
curl_easy_perform(curl);
}
AVAILABILITY
POP3 and SMTP were added in 7.31.0
RETURN VALUE
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insuf-
ficient heap space.
Note that curl_easy_setopt(3) will not actually parse the given string
so given a bad URL, it will not be detected until curl_easy_perform(3)
or similar is called.
SEE ALSO
CURLOPT_VERBOSE(3), CURLOPT_PROTOCOLS(3), CURLOPT_FORBID_REUSE(3), CUR-
LOPT_FRESH_CONNECT(3), curl_easy_perform(3), CURLINFO_REDIRECT_URL(3),
CURLOPT_PATH_AS_IS(3), CURLOPT_CURLU(3),
libcurl 7.81.0 November 26, 2021 CURLOPT_URL(3)
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