Provided by: libcurl4-doc_7.68.0-1ubuntu2.25_all bug

NAME

       CURLOPT_URL - provide the URL to use in the request

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 zero 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 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 started.

       The host part of the URL contains the address of the server that you want to connect to. This can be  the
       fully  qualified  domain name of the server, the local network name of the machine on your network or the
       IP address of the server or machine represented by either an IPv4 or IPv6 address. For example:

       http://www.example.com/

       http://hostname/

       http://192.168.0.1/

       http://[2001:1890:1112:1::20]/

       It is also possible to specify the user name, password and any supported login options  as  part  of  the
       host, for the following protocols, when connecting to servers that require authentication:

       http://user:password@www.example.com

       ftp://user:password@ftp.example.com

       smb://domain%2fuser:password@server.example.com

       imap://user:password;options@mail.example.com

       pop3://user:password;options@mail.example.com

       smtp://user:password;options@mail.example.com

       At  present  only  IMAP,  POP3  and SMTP support login options as part of the host.  For more information
       about the login options in URL syntax please see  RFC2384,  RFC5092  and  IETF  draft  draft-earhart-url-
       smtp-00.txt (Added in 7.31.0).

       The  port is optional and when not specified libcurl will use the default port based on the determined or
       specified protocol: 80 for HTTP, 21 for FTP and 25 for SMTP, etc. The  following  examples  show  how  to
       specify the port:

       http://www.example.com:8080/ - This will connect to a web server using port 8080 rather than 80.

       smtp://mail.example.com:587/ - This will connect to a SMTP server on the alternative mail port.

       The  path  part of the URL is protocol specific and whilst some examples are given below this list is not
       conclusive:

       HTTP   The path part of an HTTP request specifies the file to retrieve and from what  directory.  If  the
              directory  is  not  specified then the web server's root directory is used. If the file is omitted
              then the default document will be retrieved  for  either  the  directory  specified  or  the  root
              directory.  The  exact  resource  returned  for  each  URL  is  entirely dependent on the server's
              configuration.

              http://www.example.com - This gets the main page from the web server.

              http://www.example.com/index.html - This returns the main page by explicitly requesting it.

              http://www.example.com/contactus/  -  This  returns  the  default  document  from  the   contactus
              directory.

       FTP    The  path  part  of  an FTP request specifies the file to retrieve and from what directory. If the
              file part is omitted then libcurl downloads the directory listing for the directory specified.  If
              the  directory  is  omitted  then  the  directory  listing  for  the root / home directory will be
              returned.

              ftp://ftp.example.com - This retrieves the directory listing for the root directory.

              ftp://ftp.example.com/readme.txt - This downloads the file readme.txt from the root directory.

              ftp://ftp.example.com/libcurl/readme.txt - This downloads readme.txt from the libcurl directory.

              ftp://user:password@ftp.example.com/readme.txt - This  retrieves  the  readme.txt  file  from  the
              user's  home directory. When a username and password is specified, everything that is specified in
              the path part is relative to the user's home directory. To retrieve files from the root  directory
              or  a  directory  underneath  the  root  directory  then  the  absolute  path must be specified by
              prepending an additional forward slash to the beginning of the path.

              ftp://user:password@ftp.example.com//readme.txt - This retrieves  the  readme.txt  from  the  root
              directory when logging in as a specified user.

       SMTP   The  path  part of a SMTP request specifies the host name to present during communication with the
              mail server. If the path is omitted then libcurl will attempt to resolve the local computer's host
              name. However, this may not return the fully qualified domain name that is required by  some  mail
              servers  and  specifying  this  path allows you to set an alternative name, such as your machine's
              fully qualified domain name, which you might have obtained  from  an  external  function  such  as
              gethostname or getaddrinfo.

              smtp://mail.example.com  -  This  connects  to the mail server at example.com and sends your local
              computer's host name in the HELO / EHLO command.

              smtp://mail.example.com/client.example.com - This will send client.example.com in the HELO /  EHLO
              command to the mail server at example.com.

       POP3   The  path  part of a POP3 request specifies the message ID to retrieve. If the ID is not specified
              then a list of waiting messages is returned instead.

              pop3://user:password@mail.example.com - This lists the available messages for the user

              pop3://user:password@mail.example.com/1 - This retrieves the first message for the user

       IMAP   The path part of an IMAP request not only specifies the mailbox  to  list  (Added  in  7.30.0)  or
              select,  but can also be used to check the UIDVALIDITY of the mailbox, to specify the UID, SECTION
              (Added in 7.30.0) and PARTIAL octets (Added in 7.37.0) of the message to fetch and to specify what
              messages to search for (Added in 7.37.0).

              imap://user:password@mail.example.com - Performs a top level folder list

              imap://user:password@mail.example.com/INBOX - Performs a folder list on the user's inbox

              imap://user:password@mail.example.com/INBOX/;UID=1 - Selects the user's inbox and fetches  message
              with uid = 1

              imap://user:password@mail.example.com/INBOX/;MAILINDEX=1  -  Selects  the user's inbox and fetches
              the first message in the mail box

              imap://user:password@mail.example.com/INBOX;UIDVALIDITY=50/;UID=2  -  Selects  the  user's  inbox,
              checks the UIDVALIDITY of the mailbox is 50 and fetches message 2 if it is

              imap://user:password@mail.example.com/INBOX/;UID=3/;SECTION=TEXT  -  Selects  the user's inbox and
              fetches the text portion of message 3

              imap://user:password@mail.example.com/INBOX/;UID=4/;PARTIAL=0.1024 - Selects the user's inbox  and
              fetches the first 1024 octets of message 4

              imap://user:password@mail.example.com/INBOX?NEW  -  Selects  the  user's  inbox and checks for NEW
              messages

              imap://user:password@mail.example.com/INBOX?SUBJECT%20shadows  -  Selects  the  user's  inbox  and
              searches for messages containing "shadows" in the subject line

              For more information about the individual components of an IMAP URL please see RFC5092.

       SCP    The  path  part  of a SCP request specifies the file to retrieve and from what directory. The file
              part may not be omitted. The file is taken as an absolute path from  the  root  directory  on  the
              server.  To  specify a path relative to the user's home directory on the server, prepend ~/ to the
              path portion.   If  the  user  name  is  not  embedded  in  the  URL,  it  can  be  set  with  the
              CURLOPT_USERPWD(3) or CURLOPT_USERNAME(3) option.

              scp://user@example.com/etc/issue - This specifies the file /etc/issue

              scp://example.com/~/my-file  - This specifies the file my-file in the user's home directory on the
              server

       SFTP   The path part of a SFTP request specifies the file to retrieve and from  what  directory.  If  the
              file part is omitted then libcurl downloads the directory listing for the directory specified.  If
              the  path  ends  in  a  /  then a directory listing is returned instead of a file.  If the path is
              omitted entirely then the directory listing for the root / home directory will  be  returned.   If
              the  user  name  is  not  embedded  in  the  URL,  it  can  be  set with the CURLOPT_USERPWD(3) or
              CURLOPT_USERNAME(3) option.

              sftp://user:password@example.com/etc/issue - This specifies the file /etc/issue

              sftp://user@example.com/~/my-file - This specifies the file my-file in the user's home directory

              sftp://ssh.example.com/~/Documents/ - This requests a directory listing of the Documents directory
              under the user's home directory

       SMB    The path part of a SMB request specifies the file to retrieve and from what share and directory or
              the share to upload to and as such, may not be omitted.  If the user name is not embedded  in  the
              URL,  it can be set with the CURLOPT_USERPWD(3) or CURLOPT_USERNAME(3) option. If the user name is
              embedded in the URL then it must contain the domain name and as such, the backslash  must  be  URL
              encoded as %2f.

              smb://server.example.com/files/issue  - This specifies the file "issue" located in the root of the
              "files" share

              smb://server.example.com/files/ -T issue - This specifies the file "issue" will be uploaded to the
              root of the "files" share.

              curl supports SMB version 1 (only)

       LDAP   The path part of a LDAP request can be used to specify the: Distinguished Name, Attributes, Scope,
              Filter and Extension for a LDAP search. Each field is separated by a question mark and  when  that
              field is not required an empty string with the question mark separator should be included.

              ldap://ldap.example.com/o=My%20Organisation  -  This  will perform a LDAP search with the DN as My
              Organisation.

              ldap://ldap.example.com/o=My%20Organisation?postalAddress - This will perform the same search  but
              will only return postalAddress attributes.

              ldap://ldap.example.com/?rootDomainNamingContext  -  This  specifies  an  empty  DN  and  requests
              information about the rootDomainNamingContext attribute for an Active Directory server.

              For more information about the individual components of a LDAP URL please see RFC4516.

       RTMP   There's no official URL spec for RTMP so libcurl uses the URL syntax supported by  the  underlying
              librtmp  library.  It  has  a  syntax  where it wants a traditional URL, followed by a space and a
              series of space-separated name=value pairs.

              While space is not typically a "legal" letter, libcurl accepts them. When a user wants to pass  in
              a  '#'  (hash)  character  it will be treated as a fragment and get cut off by libcurl if provided
              literally. You will instead have to escape it by providing it as backslash and its ASCII value  in
              hexadecimal: "\23".

       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 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).

       If libcurl is built without IDN support, the server name is used exactly as specified when passed to  the
       name resolver functions.

DEFAULT

       There is no default URL. If this option isn't 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
       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.

PROTOCOLS

       All

EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "http://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 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.

SEE ALSO

       CURLOPT_VERBOSE(3),      CURLOPT_PROTOCOLS(3),     CURLOPT_FORBID_REUSE(3),     CURLOPT_FRESH_CONNECT(3),
       curl_easy_perform(3), CURLINFO_REDIRECT_URL(3), CURLOPT_PATH_AS_IS(3), CURLOPT_CURLU(3),

libcurl 7.68.0                                  December 18, 2019                                 CURLOPT_URL(3)