Tribblix: manual page: curl_url

curl_url_set(3) Introduction to Library Functions curl_url_set(3)

NAME

curl_url_set - set a URL part

SYNOPSIS

#include <curl/curl.h>

CURLUcode curl_url_set(CURLU *url,
CURLUPart part,
const char *content,
unsigned int flags);

DESCRIPTION

The url handle to work on, passed in as the first argument, must be a
handle previously created by curl_url(3) or curl_url_dup(3).

This function sets or updates individual URL components, or parts,
held by the URL object the handle identifies.

The part argument should identify the particular URL part (see list
below) to set or change, with content pointing to a null-terminated
string with the new contents for that URL part. The contents should
be in the form and encoding they would use in a URL: URL encoded.

When setting a part in the URL object that was previously already
set, it replaces the data that was previously stored for that part
with the new content.

The caller does not have to keep content around after a successful
call as this function copies the content.

Setting a part to a NULL pointer removes that part's contents from
the CURLU handle.

This function has an 8 MB maximum length limit for all provided input
strings. In the real world, excessively long fields in URLs cause
problems even if this function accepts them.

When setting or updating contents of individual URL parts,
curl_url_set(3) might accept data that would not be otherwise
possible to set in the string when it gets populated as a result of a
full URL parse. Beware. If done so, extracting a full URL later on
from such components might render an invalid URL.

The flags argument is a bitmask with independent features.

PARTS

CURLUPART_URL
Allows the full URL of the handle to be replaced. If the
handle already is populated with a URL, the new URL can be
relative to the previous.

When successfully setting a new URL, relative or absolute, the
handle contents is replaced with the components of the newly
set URL.

Pass a pointer to a null-terminated string to the url
parameter. The string must point to a correctly formatted "RFC
3986+" URL or be a NULL pointer. The URL parser only
understands and parses the subset of URLS that are
"hierarchical" and therefore contain a :// separator - not the
ones that are normally specified with only a colon separator.

By default this API only parses URLs using schemes for
protocols that are supported built-in. To make libcurl parse
URLs generically even for schemes it does not know about, the
CURLU_NON_SUPPORT_SCHEME flags bit must be set. Otherwise,
this function returns CURLUE_UNSUPPORTED_SCHEME for URL
schemes it does not recognize.

Unless CURLU_NO_AUTHORITY is set, a blank hostname is not
allowed in the URL.

When a full URL is set (parsed), the hostname component is
stored URL decoded.

CURLUPART_SCHEME
Scheme cannot be URL decoded on set. libcurl only accepts
setting schemes up to 40 bytes long.

CURLUPART_USER
If only the user part is set and not the password, the URL is
represented with a blank password.

CURLUPART_PASSWORD
If only the password part is set and not the user, the URL is
represented with a blank user.

CURLUPART_OPTIONS
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.
This function however allows users to independently set this
field.

CURLUPART_HOST
The hostname. If it is International Domain Name (IDN) the
string must then be encoded as your locale says or UTF-8 (when
WinIDN is used). If it is a bracketed IPv6 numeric address it
may contain a zone id (or you can use CURLUPART_ZONEID).

Note that if you set an IPv6 address, it gets ruined and
causes an error if you also set the CURLU_URLENCODE flag.

Unless CURLU_NO_AUTHORITY is set, a blank hostname is not
allowed to set.

CURLUPART_ZONEID
If the hostname is a numeric IPv6 address, this field can also
be set.

CURLUPART_PORT
The port number cannot be URL encoded on set. The given port
number is provided as a string and the decimal number in it
must be between 0 and 65535. Anything else returns an error.

CURLUPART_PATH
If a path is set in the URL without a leading slash, a slash
is prepended automatically.

CURLUPART_QUERY
The query part gets spaces converted to pluses when asked to
URL encode on set with the CURLU_URLENCODE bit.

If used together with the CURLU_APPENDQUERY bit, the provided
part is appended on the end of the existing query.

The question mark in the URL is not part of the actual query
contents.

CURLUPART_FRAGMENT
The hash sign in the URL is not part of the actual fragment
contents.

FLAGS

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

CURLU_APPENDQUERY
Can be used when setting the CURLUPART_QUERY component. The
provided new part is then appended at the end of the existing
query - and if the previous part did not end with an ampersand
(&), an ampersand gets inserted before the new appended part.

When CURLU_APPENDQUERY is used together with CURLU_URLENCODE,
the first '=' symbol is not URL encoded.

CURLU_NON_SUPPORT_SCHEME
If set, allows curl_url_set(3) to set a non-supported scheme.
It then of course cannot know if the provided scheme is a
valid one or not.

CURLU_URLENCODE
When set, curl_url_set(3) URL encodes the part on entry,
except for scheme, port and URL.

When setting the path component with URL encoding enabled, the
slash character is skipped.

The query part gets space-to-plus converted before the URL
conversion is applied.

This URL encoding is charset unaware and converts the input in
a byte-by-byte manner.

CURLU_DEFAULT_SCHEME
If set, allows the URL to be set without a scheme and then
sets that to the default scheme: HTTPS. Overrides the
CURLU_GUESS_SCHEME option if both are set.

CURLU_GUESS_SCHEME
If set, allows the URL to be set without a scheme and it
instead "guesses" which scheme that was intended based on the
hostname. If the outermost subdomain name matches DICT, FTP,
IMAP, LDAP, POP3 or SMTP then that scheme is used, otherwise
it picks HTTP. Conflicts with the CURLU_DEFAULT_SCHEME option
which takes precedence if both are set.

If guessing is not allowed and there is no default scheme set,
trying to parse a URL without a scheme returns error.

If the scheme ends up set as a result of guessing, i.e. it is
not actually present in the parsed URL, it can later be
figured out by using the CURLU_NO_GUESS_SCHEME flag when
subsequently getting the URL or the scheme with
curl_url_get(3).

CURLU_NO_AUTHORITY
If set, skips authority checks. The RFC allows individual
schemes to omit the host part (normally the only mandatory
part of the authority), but libcurl cannot know whether this
is permitted for custom schemes. Specifying the flag permits
empty authority sections, similar to how file scheme is
handled.

CURLU_PATH_AS_IS
When set for CURLUPART_URL, this skips the normalization of
the path. That is the procedure where libcurl otherwise
removes sequences of dot-slash and dot-dot etc. The same
option used for transfers is called CURLOPT_PATH_AS_IS(3).

CURLU_ALLOW_SPACE
If set, the URL parser allows space (ASCII 32) where possible.
The URL syntax does normally not allow spaces anywhere, but
they should be encoded as %20 or '+'. When spaces are allowed,
they are still not allowed in the scheme. When space is used
and allowed in a URL, it is stored as-is unless
CURLU_URLENCODE is also set, which then makes libcurl URL
encode the space before stored. This affects how the URL is
constructed when curl_url_get(3) is subsequently used to
extract the full URL or individual parts. (Added in 7.78.0)

CURLU_DISALLOW_USER
If set, the URL parser does not accept embedded credentials
for the CURLUPART_URL, and instead returns
CURLUE_USER_NOT_ALLOWED for such URLs.

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURLUcode rc;
CURLU *url = curl_url();
rc = curl_url_set(url, CURLUPART_URL, "https://example.com", 0);
if(!rc) {
/* change it to an FTP URL */
rc = curl_url_set(url, CURLUPART_SCHEME, "ftp", 0);
}
curl_url_cleanup(url);
}

AVAILABILITY

Added in curl 7.62.0

RETURN VALUE

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.

The input string passed to curl_url_set(3) must be shorter than eight
million bytes. Otherwise this function returns
CURLUE_MALFORMED_INPUT.

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