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.TH CURLOPT_URL 3 "November 08, 2021" "libcurl 7.80.0" "curl_easy_setopt options"

.SH NAME
CURLOPT_URL \- URL for this transfer
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_URL, char *URL);
.SH DESCRIPTION
Pass in a pointer to the \fIURL\fP 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, \fIcurl_easy_setopt(3)\fP will
still return \fICURLE_OK\fP.

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 \fICURLOPT_DEFAULT_PROTOCOL(3)\fP 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
\fICURLE_UNSUPPORTED_PROTOCOL\fP will be returned from either the
\fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP functions when you
call them. Use \fIcurl_version_info(3)\fP for detailed information of which
protocols are supported by the build of libcurl you are using.

\fICURLOPT_PROTOCOLS(3)\fP 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 \fICURLOPT_URL(3)\fP string will be ignored if \fICURLOPT_CURLU(3)\fP is
set.

\fICURLOPT_URL(3)\fP or \fICURLOPT_CURLU(3)\fP \fBmust\fP be set before a
transfer is started.

The application does not have to keep the string around after setting this
option.
.SH ENCODING
The string pointed to in the \fICURLOPT_URL(3)\fP argument is generally
expected to be a sequence of characters using an ASCII compatible encoding.

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.
.SH DEFAULT
There is no default URL. If this option is not set, no transfer can be
performed.
.SH 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 localhost 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 \fICURLOPT_PROTOCOLS(3)\fP.

User provided URLs can also be made to point to sites that redirect further on
(possibly to other protocols too). Consider your
\fICURLOPT_FOLLOWLOCATION(3)\fP and \fICURLOPT_REDIR_PROTOCOLS(3)\fP settings.
.SH PROTOCOLS
All
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

  curl_easy_perform(curl);
}
.fi
.SH AVAILABILITY
POP3 and SMTP were added in 7.31.0
.SH RETURN VALUE
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient
heap space.

Note that \fIcurl_easy_setopt(3)\fP will not actually parse the given string so
given a bad URL, it will not be detected until \fIcurl_easy_perform(3)\fP or
similar is called.
.SH "SEE ALSO"
.BR CURLOPT_VERBOSE "(3), " CURLOPT_PROTOCOLS "(3), "
.BR CURLOPT_FORBID_REUSE "(3), " CURLOPT_FRESH_CONNECT "(3), "
.BR curl_easy_perform "(3), "
.BR CURLINFO_REDIRECT_URL "(3), " CURLOPT_PATH_AS_IS "(3), " CURLOPT_CURLU "(3), "