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1---
2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_URL
5Section: 3
6Source: libcurl
7See-also:
8  - CURLINFO_REDIRECT_URL (3)
9  - CURLOPT_CURLU (3)
10  - CURLOPT_FORBID_REUSE (3)
11  - CURLOPT_FRESH_CONNECT (3)
12  - CURLOPT_PATH_AS_IS (3)
13  - CURLOPT_PROTOCOLS (3)
14  - curl_easy_perform (3)
15  - curl_url_get (3)
16  - curl_url_set (3)
17---
18
19# NAME
20
21CURLOPT_URL - URL for this transfer
22
23# SYNOPSIS
24
25~~~c
26#include <curl/curl.h>
27
28CURLcode curl_easy_setopt(CURL *handle, CURLOPT_URL, char *URL);
29~~~
30
31# DESCRIPTION
32
33Pass in a pointer to the *URL* to work with. The parameter should be a
34char * to a null-terminated string which must be URL-encoded in the following
35format:
36
37scheme://host:port/path
38
39For a greater explanation of the format please see RFC 3986.
40
41libcurl does not validate the syntax or use the URL until the transfer is
42started. Even if you set a crazy value here, curl_easy_setopt(3) might
43still return *CURLE_OK*.
44
45If the given URL is missing a scheme name (such as "http://" or "ftp://" etc)
46then libcurl guesses based on the host. If the outermost subdomain name
47matches DICT, FTP, IMAP, LDAP, POP3 or SMTP then that protocol gets used,
48otherwise HTTP is used. Since 7.45.0 guessing can be disabled by setting a
49default protocol, see CURLOPT_DEFAULT_PROTOCOL(3) for details.
50
51Should the protocol, either as specified by the URL scheme or deduced by
52libcurl from the hostname, not be supported by libcurl then
53*CURLE_UNSUPPORTED_PROTOCOL* is returned from either the curl_easy_perform(3)
54or curl_multi_perform(3) functions when you call them. Use
55curl_version_info(3) for detailed information of which protocols are supported
56by the build of libcurl you are using.
57
58CURLOPT_PROTOCOLS_STR(3) can be used to limit what protocols libcurl may
59use for this transfer, independent of what libcurl has been compiled to
60support. That may be useful if you accept the URL from an external source and
61want to limit the accessibility.
62
63The CURLOPT_URL(3) string is ignored if CURLOPT_CURLU(3) is set.
64
65Either CURLOPT_URL(3) or CURLOPT_CURLU(3) must be set before a
66transfer is started.
67
68The application does not have to keep the string around after setting this
69option.
70
71The parser used for handling the URL set with CURLOPT_URL(3) is the same
72that curl_url_set(3) uses.
73
74# ENCODING
75
76The string pointed to in the CURLOPT_URL(3) argument is generally
77expected to be a sequence of characters using an ASCII compatible encoding.
78
79If libcurl is built with IDN support, the server name part of the URL can use
80an "international name" by using the current encoding (according to locale) or
81UTF-8 (when winidn is used; or a Windows Unicode build using libidn2).
82
83If libcurl is built without IDN support, the server name is used exactly as
84specified when passed to the name resolver functions.
85
86# DEFAULT
87
88There is no default URL. If this option is not set, no transfer can be
89performed.
90
91# SECURITY CONCERNS
92
93Applications may at times find it convenient to allow users to specify URLs
94for various purposes and that string would then end up fed to this option.
95
96Getting a URL from an external untrusted party brings several security
97concerns:
98
99If you have an application that runs as or in a server application, getting an
100unfiltered URL can easily trick your application to access a local resource
101instead of a remote. Protecting yourself against localhost accesses is hard
102when accepting user provided URLs.
103
104Such custom URLs can also access other ports than you planned as port numbers
105are part of the regular URL format. The combination of a local host and a
106custom port number can allow external users to play tricks with your local
107services.
108
109Accepting external URLs may also use other protocols than http:// or other
110common ones. Restrict what accept with CURLOPT_PROTOCOLS(3).
111
112User provided URLs can also be made to point to sites that redirect further on
113(possibly to other protocols too). Consider your
114CURLOPT_FOLLOWLOCATION(3) and CURLOPT_REDIR_PROTOCOLS(3) settings.
115
116# PROTOCOLS
117
118All
119
120# EXAMPLE
121
122~~~c
123int main(void)
124{
125  CURL *curl = curl_easy_init();
126  if(curl) {
127    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
128
129    curl_easy_perform(curl);
130  }
131}
132~~~
133
134# AVAILABILITY
135
136POP3 and SMTP were added in 7.31.0
137
138# RETURN VALUE
139
140Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient
141heap space.
142
143Note that curl_easy_setopt(3) does not parse the given string so given a
144bad URL, it is not detected until curl_easy_perform(3) or similar is
145called.
146