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CentOS 7.0 - man page for curl_easy_setopt (centos section 3)

curl_easy_setopt(3)			  libcurl Manual		      curl_easy_setopt(3)

NAME
       curl_easy_setopt - set options for a curl easy handle

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLoption option, parameter);

DESCRIPTION
       curl_easy_setopt() is used to tell libcurl how to behave. By using the appropriate options
       to curl_easy_setopt, you can change libcurl's behavior.	All  options  are  set	with  the
       option  followed  by  a	parameter.  That  parameter can be a long, a function pointer, an
       object pointer or a curl_off_t, depending on what the specific option expects.  Read  this
       manual  carefully as bad input values may cause libcurl to behave badly!  You can only set
       one option in each function call. A typical application uses many curl_easy_setopt() calls
       in the setup phase.

       Options	set  with  this  function  call are valid for all forthcoming transfers performed
       using this handle.  The options are not in any way reset between transfers, so if you want
       subsequent  transfers  with different options, you must change them between the transfers.
       You can optionally reset all options back to internal default with curl_easy_reset(3).

       Strings passed to libcurl as 'char *' arguments, are  copied  by  the  library;	thus  the
       string	storage   associated   to   the   pointer   argument  may  be  overwritten  after
       curl_easy_setopt() returns. Exceptions to this rule are described in  the  option  details
       below.

       Before  version	7.17.0,  strings  were	not copied. Instead the user was forced keep them
       available until libcurl no longer needed them.

       The handle is the return code from a curl_easy_init(3) or curl_easy_duphandle(3) call.

BEHAVIOR OPTIONS
       CURLOPT_VERBOSE
	      Set the parameter to 1 to get the library to display a lot of  verbose  information
	      about  its operations. Very useful for libcurl and/or protocol debugging and under-
	      standing. The verbose information will be sent to stderr, or the	stream	set  with
	      CURLOPT_STDERR.

	      You  hardly  ever want this set in production use, you will almost always want this
	      when you debug/report problems. Another neat  option  for  debugging  is	the  CUR-
	      LOPT_DEBUGFUNCTION.

       CURLOPT_HEADER
	      A  parameter  set  to 1 tells the library to include the header in the body output.
	      This is only relevant for protocols that actually have headers preceding	the  data
	      (like HTTP).

       CURLOPT_NOPROGRESS
	      Pass  a long. If set to 1, it tells the library to shut off the progress meter com-
	      pletely. It will also prevent the CURLOPT_PROGRESSFUNCTION from getting called.

	      Future versions of libcurl are likely to not have any built-in  progress	meter  at
	      all.

       CURLOPT_NOSIGNAL
	      Pass  a  long.  If  it is 1, libcurl will not use any functions that install signal
	      handlers or any functions that cause signals to be sent to the process. This option
	      is mainly here to allow multi-threaded unix applications to still set/use all time-
	      out options etc, without risking getting signals.  (Added in 7.10)

	      If this option is set and libcurl has been built with the standard  name	resolver,
	      timeouts	will  not  occur  while  the name resolve takes place.	Consider building
	      libcurl with c-ares support to enable asynchronous DNS lookups, which enables  nice
	      timeouts for name resolves without signals.

	      Setting  CURLOPT_NOSIGNAL  to  1 makes libcurl NOT ask the system to ignore SIGPIPE
	      signals, which otherwise are sent by the system when  trying  to	send  data  to	a
	      socket  which  is  closed  in the other end. libcurl makes an effort to never cause
	      such SIGPIPEs to trigger, but some operating systems have no way to avoid them  and
	      even  on	those  that  have there are some corner cases when they may still happen,
	      contrary to our desire. In addition, using  CURLAUTH_NTLM_WB  authentication  could
	      cause a SIGCHLD signal to be raised.

       CURLOPT_WILDCARDMATCH
	      Set  this  option  to  1 if you want to transfer multiple files according to a file
	      name pattern. The pattern can be specified as part of the CURLOPT_URL option, using
	      an  fnmatch-like	pattern  (Shell  Pattern  Matching) in the last part of URL (file
	      name).

	      By default, libcurl uses its internal wildcard  matching	implementation.  You  can
	      provide your own matching function by the CURLOPT_FNMATCH_FUNCTION option.

	      This feature is only supported by the FTP download for now.

	      A brief introduction of its syntax follows:

	      * - ASTERISK
		     ftp://example.com/some/path/*.txt (for all txt's from the root directory)

	      ? - QUESTION MARK
		     Question mark matches any (exactly one) character.

		     ftp://example.com/some/path/photo?.jpeg

	      [ - BRACKET EXPRESSION
		     The  left bracket opens a bracket expression. The question mark and asterisk
		     have no special meaning in a bracket  expression.	Each  bracket  expression
		     ends  by  the right bracket and matches exactly one character. Some examples
		     follow:

		     [a-zA-Z0-9] or [f-gF-G] - character interval

		     [abc] - character enumeration

		     [^abc] or [!abc] - negation

		     [[:name:]] class  expression.  Supported  classes	are  alnum,lower,  space,
		     alpha, digit, print, upper, blank, graph, xdigit.

		     [][-!^] - special case - matches only '-', ']', '[', '!' or '^'. These char-
		     acters have no special purpose.

		     [\[\]\\] - escape syntax. Matches '[', ']' or '\'.

		     Using the rules above, a file name pattern can be constructed:

		     ftp://example.com/some/path/[a-z[:upper:]\\].jpeg

       (This was added in 7.21.0)

CALLBACK OPTIONS
       CURLOPT_WRITEFUNCTION
	      Pass a pointer to a function that matches the following prototype: size_t function(
	      char *ptr, size_t size, size_t nmemb, void *userdata); This function gets called by
	      libcurl as soon as there is data received that needs to be saved. The size  of  the
	      data  pointed  to  by ptr is size multiplied with nmemb, it will not be zero termi-
	      nated. Return the number of bytes actually taken care of. If  that  amount  differs
	      from the amount passed to your function, it'll signal an error to the library. This
	      will abort the transfer and return CURLE_WRITE_ERROR.

	      From 7.18.0, the function can return CURL_WRITEFUNC_PAUSE  which	then  will  cause
	      writing  to  this  connection  to become paused. See curl_easy_pause(3) for further
	      details.

	      This function may be called with zero bytes data if the transferred file is empty.

	      Set this option to NULL to get the internal default function. The internal  default
	      function will write the data to the FILE * given with CURLOPT_WRITEDATA.

	      Set the userdata argument with the CURLOPT_WRITEDATA option.

	      The  callback  function will be passed as much data as possible in all invokes, but
	      you cannot possibly make any assumptions. It may be one byte, it may be  thousands.
	      The maximum amount of body data that can be passed to the write callback is defined
	      in the curl.h header file: CURL_MAX_WRITE_SIZE (the usual default is 16K).  If  you
	      however have CURLOPT_HEADER set, which sends header data to the write callback, you
	      can get up to CURL_MAX_HTTP_HEADER bytes of header data passed into it.  This  usu-
	      ally means 100K.

       CURLOPT_WRITEDATA
	      Data  pointer to pass to the file write function. If you use the CURLOPT_WRITEFUNC-
	      TION option, this is the pointer you'll get as input. If you don't use a	callback,
	      you must pass a 'FILE *' as libcurl will pass this to fwrite() when writing data.

	      The  internal  CURLOPT_WRITEFUNCTION  will  write the data to the FILE * given with
	      this option, or to stdout if this option hasn't been set.

	      If you're using libcurl as a win32 DLL, you MUST use the	CURLOPT_WRITEFUNCTION  if
	      you set this option or you will experience crashes.

	      This option is also known with the older name CURLOPT_FILE, the name CURLOPT_WRITE-
	      DATA was introduced in 7.9.7.

       CURLOPT_READFUNCTION
	      Pass a pointer to a function that matches the following prototype: size_t function(
	      void *ptr, size_t size, size_t nmemb, void *userdata); This function gets called by
	      libcurl as soon as it needs to read data in order to send it to the peer. The  data
	      area  pointed at by the pointer ptr may be filled with at most size multiplied with
	      nmemb number of bytes. Your function must return the actual number  of  bytes  that
	      you  stored in that memory area. Returning 0 will signal end-of-file to the library
	      and cause it to stop the current transfer.

	      If you stop the current transfer by returning  0	"pre-maturely"	(i.e  before  the
	      server  expected	it,  like when you've said you will upload N bytes and you upload
	      less than N bytes), you may experience that the server "hangs" waiting for the rest
	      of the data that won't come.

	      The  read  callback  may	return	CURL_READFUNC_ABORT to stop the current operation
	      immediately, resulting in a CURLE_ABORTED_BY_CALLBACK error code from the  transfer
	      (Added in 7.12.1)

	      From  7.18.0,  the  function  can  return CURL_READFUNC_PAUSE which then will cause
	      reading from this connection to become paused. See curl_easy_pause(3)  for  further
	      details.

	      Bugs:  when  doing  TFTP uploads, you must return the exact amount of data that the
	      callback wants, or it will be considered the final packet by the server end and the
	      transfer will end there.

	      If  you  set  this  callback  pointer  to NULL, or don't set it at all, the default
	      internal read function will be used. It is doing an fread() on the FILE *  userdata
	      set with CURLOPT_READDATA.

       CURLOPT_READDATA
	      Data pointer to pass to the file read function. If you use the CURLOPT_READFUNCTION
	      option, this is the pointer you'll get as input. If you don't specify a read  call-
	      back  but  instead  rely on the default internal read function, this data must be a
	      valid readable FILE *.

	      If you're using libcurl as a win32 DLL, you MUST use a CURLOPT_READFUNCTION if  you
	      set this option.

	      This option was also known by the older name CURLOPT_INFILE, the name CURLOPT_READ-
	      DATA was introduced in 7.9.7.

       CURLOPT_IOCTLFUNCTION
	      Pass a pointer to a function that matches the following prototype: curlioerr  func-
	      tion(CURL  *handle,  int cmd, void *clientp);. This function gets called by libcurl
	      when something special I/O-related needs to be done that the library  can't  do  by
	      itself.  For now, rewinding the read data stream is the only action it can request.
	      The rewinding of the read data stream may be necessary when doing  a  HTTP  PUT  or
	      POST with a multi-pass authentication method.  (Option added in 7.12.3).

	      Use CURLOPT_SEEKFUNCTION instead to provide seeking!

       CURLOPT_IOCTLDATA
	      Pass  a pointer that will be untouched by libcurl and passed as the 3rd argument in
	      the ioctl callback set with CURLOPT_IOCTLFUNCTION.  (Option added in 7.12.3)

       CURLOPT_SEEKFUNCTION
	      Pass a pointer to a function  that  matches  the	following  prototype:  int  func-
	      tion(void  *instream,  curl_off_t offset, int origin); This function gets called by
	      libcurl to seek to a certain position in the input stream and can be used  to  fast
	      forward  a file in a resumed upload (instead of reading all uploaded bytes with the
	      normal read function/callback). It is also called to rewind a stream when  doing	a
	      HTTP  PUT  or POST with a multi-pass authentication method. The function shall work
	      like "fseek" or "lseek" and accepted SEEK_SET, SEEK_CUR and  SEEK_END  as  argument
	      for  origin,  although  (in 7.18.0) libcurl only passes SEEK_SET. The callback must
	      return 0 (CURL_SEEKFUNC_OK) on success, 1 (CURL_SEEKFUNC_FAIL) to cause the  upload
	      operation  to  fail  or  2 (CURL_SEEKFUNC_CANTSEEK) to indicate that while the seek
	      failed, libcurl is free to work around the problem  if  possible.  The  latter  can
	      sometimes be done by instead reading from the input or similar.

	      If  you  forward	the input arguments directly to "fseek" or "lseek", note that the
	      data type for offset is not the same as defined for  curl_off_t  on  many  systems!
	      (Option added in 7.18.0)

       CURLOPT_SEEKDATA
	      Data pointer to pass to the file seek function. If you use the CURLOPT_SEEKFUNCTION
	      option, this is the pointer you'll get as input. If you don't specify a seek  call-
	      back, NULL is passed. (Option added in 7.18.0)

       CURLOPT_SOCKOPTFUNCTION
	      Pass  a  pointer	to  a  function  that  matches the following prototype: int func-
	      tion(void *clientp, curl_socket_t curlfd,  curlsocktype  purpose);.  This  function
	      gets  called  by libcurl after the socket() call but before the connect() call. The
	      callback's purpose argument  identifies  the  exact  purpose  for  this  particular
	      socket:

	      CURLSOCKTYPE_IPCXN  for  actively  created  connections  or  since 7.28.0 CURLSOCK-
	      TYPE_ACCEPT for FTP when the connection was setup with PORT/EPSV (in  earlier  ver-
	      sions these sockets weren't passed to this callback).

	      Future  versions	of libcurl may support more purposes. It passes the newly created
	      socket descriptor so additional setsockopt() calls can be done at the  user's  dis-
	      cretion.	 Return 0 (zero) from the callback on success. Return 1 from the callback
	      function to signal an unrecoverable error to the library	and  it  will  close  the
	      socket and return CURLE_COULDNT_CONNECT.	(Option added in 7.16.0)

	      Added  in  7.21.5, the callback function may return CURL_SOCKOPT_ALREADY_CONNECTED,
	      which tells libcurl that the socket is in fact already connected and  then  libcurl
	      will not attempt to connect it.

       CURLOPT_SOCKOPTDATA
	      Pass  a  pointer that will be untouched by libcurl and passed as the first argument
	      in the sockopt callback set with CURLOPT_SOCKOPTFUNCTION.  (Option added in 7.16.0)

       CURLOPT_OPENSOCKETFUNCTION
	      Pass a pointer to a function that matches the  following	prototype:  curl_socket_t
	      function(void *clientp, curlsocktype purpose, struct curl_sockaddr *address);. This
	      function gets called by libcurl instead of the socket(2) call. The callback's  pur-
	      pose  argument  identifies  the exact purpose for this particular socket: CURLSOCK-
	      TYPE_IPCXN is for IP based connections. Future versions of libcurl may support more
	      purposes. It passes the resolved peer address as a address argument so the callback
	      can modify the address or refuse to connect at all. The  callback  function  should
	      return  the socket or CURL_SOCKET_BAD in case no connection could be established or
	      another error was detected. Any additional setsockopt(2) calls can be done  on  the
	      socket  at  the  user's discretion.  CURL_SOCKET_BAD return value from the callback
	      function will signal an unrecoverable error to  the  library  and  it  will  return
	      CURLE_COULDNT_CONNECT.   This  return code can be used for IP address blacklisting.
	      The default behavior is:
		 return socket(addr->family, addr->socktype, addr->protocol);
	      (Option added in 7.17.1.)

       CURLOPT_OPENSOCKETDATA
	      Pass a pointer that will be untouched by libcurl and passed as the  first  argument
	      in  the  opensocket callback set with CURLOPT_OPENSOCKETFUNCTION.  (Option added in
	      7.17.1.)

       CURLOPT_CLOSESOCKETFUNCTION
	      Pass a pointer to a function  that  matches  the	following  prototype:  int  func-
	      tion(void  *clientp,  curl_socket_t  item);.  This  function gets called by libcurl
	      instead of the close(3) or closesocket(3) call when sockets are closed (not for any
	      other file descriptors). This is pretty much the reverse to the CURLOPT_OPENSOCKET-
	      FUNCTION option. Return 0 to signal success and 1 if there was an  error.   (Option
	      added in 7.21.7)

       CURLOPT_CLOSESOCKETDATA
	      Pass  a  pointer that will be untouched by libcurl and passed as the first argument
	      in the closesocket callback set with CURLOPT_CLOSESOCKETFUNCTION.  (Option added in
	      7.21.7)

       CURLOPT_PROGRESSFUNCTION
	      Pass  a  pointer	to  a  function  that  matches the following prototype: int func-
	      tion(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow);	.
	      This function gets called by libcurl instead of its internal equivalent with a fre-
	      quent interval during operation (roughly once per second or sooner)  no  matter  if
	      data  is	being  transferred  or not.  Unknown/unused argument values passed to the
	      callback will be set to zero (like if you only download data, the upload size  will
	      remain  0).  Returning  a  non-zero  value from this callback will cause libcurl to
	      abort the transfer and return CURLE_ABORTED_BY_CALLBACK.

	      If you transfer data with the multi interface, this function  will  not  be  called
	      during  periods  of  idleness unless you call the appropriate libcurl function that
	      performs transfers.

	      CURLOPT_NOPROGRESS must be set to 0 to make this function actually get called.

       CURLOPT_PROGRESSDATA
	      Pass a pointer that will be untouched by libcurl and passed as the  first  argument
	      in the progress callback set with CURLOPT_PROGRESSFUNCTION.

       CURLOPT_HEADERFUNCTION
	      Pass a pointer to a function that matches the following prototype: size_t function(
	      void *ptr, size_t size, size_t nmemb, void *userdata);. This function  gets  called
	      by  libcurl  as  soon  as  it has received header data. The header callback will be
	      called once for each header and only complete header lines are  passed  on  to  the
	      callback.  Parsing headers is very easy using this. The size of the data pointed to
	      by ptr is size multiplied with nmemb. Do not assume that the header  line  is  zero
	      terminated!  The	pointer named userdata is the one you set with the CURLOPT_WRITE-
	      HEADER option. The callback function must return the number of bytes actually taken
	      care of. If that amount differs from the amount passed to your function, it'll sig-
	      nal  an  error  to  the  library.  This  will  abort  the   transfer   and   return
	      CURL_WRITE_ERROR.

	      A   complete   HTTP   header  that  is  passed  to  this	function  can  be  up  to
	      CURL_MAX_HTTP_HEADER (100K) bytes.

	      If this option is not set, or if it is set to NULL,  but	CURLOPT_HEADERDATA  (CUR-
	      LOPT_WRITEHEADER) is set to anything but NULL, the function used to accept response
	      data will be used instead. That is, it will be the  function  specified  with  CUR-
	      LOPT_WRITEFUNCTION, or if it is not specified or NULL - the default, stream-writing
	      function.

	      It's important to note that the callback will be invoked for  the  headers  of  all
	      responses received after initiating a request and not just the final response. This
	      includes all responses which occur during authentication negotiation. If	you  need
	      to  operate  on  only the headers from the final response, you will need to collect
	      headers in the callback yourself and use HTTP status lines, for example, to delimit
	      response boundaries.

	      When  a  server  sends  a  chunked encoded transfer, it may contain a trailer. That
	      trailer is identical to a HTTP header and if such  a  trailer  is  received  it  is
	      passed  to  the  application using this callback as well. There are several ways to
	      detect it being a trailer and not  an  ordinary  header:	1)  it	comes  after  the
	      response-body. 2) it comes after the final header line (CR LF) 3) a Trailer: header
	      among the regular response-headers mention what header(s) to expect in the trailer.

	      For non-HTTP protocols like FTP, POP3, IMAP and SMTP this function will get  called
	      with the server responses to the commands that libcurl sends.

       CURLOPT_WRITEHEADER
	      (This  option  is  also  known  as CURLOPT_HEADERDATA) Pass a pointer to be used to
	      write the header part of the received data to. If you don't use  CURLOPT_WRITEFUNC-
	      TION  or	CURLOPT_HEADERFUNCTION	to take care of the writing, this must be a valid
	      FILE * as the internal default will then be a plain fwrite().  See  also	the  CUR-
	      LOPT_HEADERFUNCTION option above on how to set a custom get-all-headers callback.

       CURLOPT_DEBUGFUNCTION
	      Pass   a	 pointer  to  a  function  that  matches  the  following  prototype:  int
	      curl_debug_callback (CURL *, curl_infotype, char *, size_t, void *); CURLOPT_DEBUG-
	      FUNCTION	replaces  the  standard  debug	function used when CURLOPT_VERBOSE  is in
	      effect. This callback receives debug information, as specified with the  curl_info-
	      type  argument.  This  function  must  return 0.	The data pointed to by the char *
	      passed to this function WILL NOT be zero terminated, but will  be  exactly  of  the
	      size as told by the size_t argument.

	      Available curl_infotype values:

	      CURLINFO_TEXT
		     The data is informational text.

	      CURLINFO_HEADER_IN
		     The data is header (or header-like) data received from the peer.

	      CURLINFO_HEADER_OUT
		     The data is header (or header-like) data sent to the peer.

	      CURLINFO_DATA_IN
		     The data is protocol data received from the peer.

	      CURLINFO_DATA_OUT
		     The data is protocol data sent to the peer.

       CURLOPT_DEBUGDATA
	      Pass  a pointer to whatever you want passed in to your CURLOPT_DEBUGFUNCTION in the
	      last void * argument. This pointer is not used by libcurl, it is only passed to the
	      callback.

       CURLOPT_SSL_CTX_FUNCTION
	      This option does only function for libcurl powered by OpenSSL. If libcurl was built
	      against another SSL library, this functionality is absent.

	      Pass a pointer to a function that matches the following prototype: CURLcode sslctx-
	      fun(CURL	*curl,	void  *sslctx,	void *parm); This function gets called by libcurl
	      just before the initialization of a SSL connection after having processed all other
	      SSL related options to give a last chance to an application to modify the behaviour
	      of openssl's ssl initialization. The sslctx parameter is actually a pointer  to  an
	      openssl  SSL_CTX.  If  an error is returned no attempt to establish a connection is
	      made and the perform operation will return the error code from this callback  func-
	      tion.   Set the parm argument with the CURLOPT_SSL_CTX_DATA option. This option was
	      introduced in 7.11.0.

	      This function will get called on all new connections made to a server,  during  the
	      SSL negotiation. The SSL_CTX pointer will be a new one every time.

	      To use this properly, a non-trivial amount of knowledge of the openssl libraries is
	      necessary. For example, using this function allows you to use openssl callbacks  to
	      add  additional validation code for certificates, and even to change the actual URI
	      of a HTTPS request (example used in the lib509 test case).  See  also  the  example
	      section for a replacement of the key, certificate and trust file settings.

       CURLOPT_SSL_CTX_DATA
	      Data  pointer  to  pass  to  the	ssl  context  callback	set  by  the  option CUR-
	      LOPT_SSL_CTX_FUNCTION, this is the pointer you'll get as third parameter, otherwise
	      NULL. (Added in 7.11.0)

       CURLOPT_CONV_TO_NETWORK_FUNCTION

       CURLOPT_CONV_FROM_NETWORK_FUNCTION

       CURLOPT_CONV_FROM_UTF8_FUNCTION
	      Pass  a  pointer to a function that matches the following prototype: CURLcode func-
	      tion(char *ptr, size_t length);

	      These three options apply to non-ASCII platforms only.  They are available only  if
	      CURL_DOES_CONVERSIONS  was  defined  when libcurl was built. When this is the case,
	      curl_version_info(3) will return the CURL_VERSION_CONV feature bit set.

	      The data to be converted is in a buffer pointed  to  by  the  ptr  parameter.   The
	      amount of data to convert is indicated by the length parameter.  The converted data
	      overlays the input data in the buffer pointed to by the  ptr  parameter.	 CURLE_OK
	      should  be returned upon successful conversion.  A CURLcode return value defined by
	      curl.h, such as CURLE_CONV_FAILED, should be returned if an error was encountered.

	      CURLOPT_CONV_TO_NETWORK_FUNCTION	and  CURLOPT_CONV_FROM_NETWORK_FUNCTION   convert
	      between the host encoding and the network encoding.  They are used when commands or
	      ASCII data are sent/received over the network.

	      CURLOPT_CONV_FROM_UTF8_FUNCTION is called to convert from UTF8 into the host encod-
	      ing.  It is required only for SSL processing.

	      If you set a callback pointer to NULL, or don't set it at all, the built-in libcurl
	      iconv functions will be used.  If HAVE_ICONV  was  not  defined  when  libcurl  was
	      built,   and   no  callback  has	been  established,  conversion	will  return  the
	      CURLE_CONV_REQD error code.

	      If HAVE_ICONV is defined, CURL_ICONV_CODESET_OF_HOST must  also  be  defined.   For
	      example:

	       #define CURL_ICONV_CODESET_OF_HOST "IBM-1047"

	      The  iconv  code in libcurl will default the network and UTF8 codeset names as fol-
	      lows:

	       #define CURL_ICONV_CODESET_OF_NETWORK "ISO8859-1"

	       #define CURL_ICONV_CODESET_FOR_UTF8   "UTF-8"

	      You will need to override these definitions if they are different on your system.

       CURLOPT_INTERLEAVEFUNCTION
	      Pass a pointer to a function that matches the following prototype: size_t function(
	      void *ptr, size_t size, size_t nmemb, void *userdata). This function gets called by
	      libcurl as soon as it has received interleaved RTP data. This function gets  called
	      for each $ block and therefore contains exactly one upper-layer protocol unit (e.g.
	      one RTP packet). Curl writes the interleaved header as well as  the  included  data
	      for  each  call.	The first byte is always an ASCII dollar sign. The dollar sign is
	      followed by a one byte channel identifier and then a 2 byte integer length in  net-
	      work  byte  order. See RFC2326 Section 10.12 for more information on how RTP inter-
	      leaving behaves. If unset or set to NULL, curl will use the default write function.

	      Interleaved RTP poses some challenges for the client application. Since the  stream
	      data is sharing the RTSP control connection, it is critical to service the RTP in a
	      timely fashion. If the RTP data is not handled quickly,  subsequent  response  pro-
	      cessing  may become unreasonably delayed and the connection may close. The applica-
	      tion may use CURL_RTSPREQ_RECEIVE to service RTP data when no requests are desired.
	      If  the  application  makes a request, (e.g.  CURL_RTSPREQ_PAUSE) then the response
	      handler will process any pending RTP data before marking the request  as	finished.
	      (Added in 7.20.0)

       CURLOPT_INTERLEAVEDATA
	      This is the userdata pointer that will be passed to CURLOPT_INTERLEAVEFUNCTION when
	      interleaved RTP data is received. (Added in 7.20.0)

       CURLOPT_CHUNK_BGN_FUNCTION
	      Pass a pointer to a function that matches the following  prototype:  long  function
	      (const  void  *transfer_info, void *ptr, int remains). This function gets called by
	      libcurl before a part of the stream is going to be  transferred  (if  the  transfer
	      supports chunks).

	      This callback makes sense only when using the CURLOPT_WILDCARDMATCH option for now.

	      The  target  of  transfer_info parameter is a "feature depended" structure. For the
	      FTP wildcard download, the target is  curl_fileinfo  structure  (see  curl/curl.h).
	      The  parameter  ptr is a pointer given by CURLOPT_CHUNK_DATA. The parameter remains
	      contains number of chunks remaining per the transfer. If the feature is not  avail-
	      able, the parameter has zero value.

	      Return  CURL_CHUNK_BGN_FUNC_OK  if  everything is fine, CURL_CHUNK_BGN_FUNC_SKIP if
	      you want to skip the concrete chunk or CURL_CHUNK_BGN_FUNC_FAIL to tell libcurl  to
	      stop if some error occurred.  (This was added in 7.21.0)

       CURLOPT_CHUNK_END_FUNCTION
	      Pass  a  pointer	to  a  function  that matches the following prototype: long func-
	      tion(void *ptr). This function gets called by libcurl as soon  as  a  part  of  the
	      stream has been transferred (or skipped).

	      Return  CURL_CHUNK_END_FUNC_OK if everything is fine or CURL_CHUNK_END_FUNC_FAIL to
	      tell the lib to stop if some error occurred.  (This was added in 7.21.0)

       CURLOPT_CHUNK_DATA
	      Pass a pointer that will be untouched by libcurl and passed as the ptr argument  to
	      the CURL_CHUNK_BGN_FUNTION and CURL_CHUNK_END_FUNTION.  (This was added in 7.21.0)

       CURLOPT_FNMATCH_FUNCTION
	      Pass  a  pointer	to  a  function  that  matches the following prototype: int func-
	      tion(void  *ptr,	const  char  *pattern,	const  char   *string)	 prototype   (see
	      curl/curl.h). It is used internally for the wildcard matching feature.

	      Return   CURL_FNMATCHFUNC_MATCH	if  pattern  matches  the  string,  CURL_FNMATCH-
	      FUNC_NOMATCH if not or CURL_FNMATCHFUNC_FAIL if an error occurred.  (This was added
	      in 7.21.0)

       CURLOPT_FNMATCH_DATA
	      Pass  a pointer that will be untouched by libcurl and passed as the ptr argument to
	      the CURL_FNMATCH_FUNCTION. (This was added in 7.21.0)

ERROR OPTIONS
       CURLOPT_ERRORBUFFER
	      Pass a char * to a buffer that the libcurl may store human readable error  messages
	      in.  This may be more helpful than just the return code from curl_easy_perform. The
	      buffer must be at least CURL_ERROR_SIZE big.  Although this argument is a 'char *',
	      it  does not describe an input string.  Therefore the (probably undefined) contents
	      of the buffer is NOT copied by the library. You must keep  the  associated  storage
	      available  until	libcurl  no longer needs it. Failing to do so will cause very odd
	      behavior or even crashes. libcurl will need it until you call  curl_easy_cleanup(3)
	      or you set the same option again to use a different pointer.

	      Use CURLOPT_VERBOSE and CURLOPT_DEBUGFUNCTION to better debug/trace why errors hap-
	      pen.

	      If the library does not return an error, the buffer may not have been  touched.  Do
	      not rely on the contents in those cases.

       CURLOPT_STDERR
	      Pass  a FILE * as parameter. Tell libcurl to use this stream instead of stderr when
	      showing the progress meter and displaying CURLOPT_VERBOSE data.

       CURLOPT_FAILONERROR
	      A parameter set to 1 tells the library to fail silently if the HTTP  code  returned
	      is equal to or larger than 400. The default action would be to return the page nor-
	      mally, ignoring that code.

	      This method is not fail-safe and there are occasions where non-successful  response
	      codes will slip through, especially when authentication is involved (response codes
	      401 and 407).

	      You might get  some  amounts  of	headers  transferred  before  this  situation  is
	      detected,  like when a "100-continue" is received as a response to a POST/PUT and a
	      401 or 407 is received immediately afterwards.

NETWORK OPTIONS
       CURLOPT_URL
	      Pass in a pointer to the actual URL to deal 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.

	      If  the  given URL lacks the scheme, or protocol, part ("http://" or "ftp://" etc),
	      libcurl will attempt to resolve which protocol to use based on the given host mame.
	      If  the protocol is not supported, libcurl will return (CURLE_UNSUPPORTED_PROTOCOL)
	      when  you  call  curl_easy_perform(3)  or  curl_multi_perform(3).   Use	curl_ver-
	      sion_info(3) for detailed information on which protocols are supported.

	      The  host  part of the URL contains the address of the server that you want to con-
	      nect to. This can be the fully qualified domain name of the server, the local  net-
	      work 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 and password as part of the host,  for
	      some protocols, when connecting to servers that require authentication.

	      For example the following types of authentication support this:

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

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

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

	      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  alterna-
	      tive 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 a HTTP request specifies the file to retrieve and from what direc-
	      tory.  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 con-
	      tactus directory.

	      FTP

	      The path part of an FTP request specifies the file to retrieve and from what direc-
	      tory.  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 direc-
	      tory.

	      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, every-
	      thing 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 direc-
	      tory 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  communi-
	      cation  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 geth-
	      ostname 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 mailbox (message)  to  retrieve.   If
	      the mailbox is not specified then a list of waiting messages is returned instead.

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

	      SCP

	      The path part of a SCP request specifies the file to retrieve and from what  direc-
	      tory.  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  or  CURLOPT_USERNAME
	      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 direc-
	      tory.  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 or CURLOPT_USERNAME
	      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 Doc-
	      uments directory under the user's home directory

	      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.

	      NOTES

	      Starting with version 7.20.0, the fragment part of the URI will not be sent as part
	      of the path, which was previously the case.

	      CURLOPT_URL  is  the  only  option  that must be set before curl_easy_perform(3) is
	      called.

	      CURLOPT_PROTOCOLS 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 accessi-
	      bility.

       CURLOPT_PROTOCOLS
	      Pass a long that holds a bitmask of CURLPROTO_* defines. If used, this bitmask lim-
	      its what protocols libcurl may use in the transfer.  This  allows  you  to  have	a
	      libcurl  built to support a wide range of protocols but still limit specific trans-
	      fers to only be allowed to use a subset of them. By default libcurl will accept all
	      protocols it supports. See also CURLOPT_REDIR_PROTOCOLS. (Added in 7.19.4)

       CURLOPT_REDIR_PROTOCOLS
	      Pass a long that holds a bitmask of CURLPROTO_* defines. If used, this bitmask lim-
	      its what protocols libcurl may use in a transfer that it follows to in  a  redirect
	      when CURLOPT_FOLLOWLOCATION is enabled. This allows you to limit specific transfers
	      to only be allowed to use a subset of protocols in redirections. By default libcurl
	      will  allow all protocols except for FILE and SCP. This is a difference compared to
	      pre-7.19.4 versions which unconditionally would follow to all protocols  supported.
	      (Added in 7.19.4)

       CURLOPT_PROXY
	      Set HTTP proxy to use. The parameter should be a char * to a zero terminated string
	      holding the host name or dotted IP address. To specify port number in this  string,
	      append  :[port]  to the end of the host name. The proxy string may be prefixed with
	      [protocol]:// since any such prefix will be ignored. The proxy's	port  number  may
	      optionally  be  specified  with the separate option. If not specified, libcurl will
	      default to using port 1080 for proxies.  CURLOPT_PROXYPORT.

	      When you tell the library to use a HTTP proxy, libcurl will  transparently  convert
	      operations  to  HTTP even if you specify an FTP URL etc. This may have an impact on
	      what other features of the library you can use, such as CURLOPT_QUOTE  and  similar
	      FTP  specifics  that don't work unless you tunnel through the HTTP proxy. Such tun-
	      neling is activated with CURLOPT_HTTPPROXYTUNNEL.

	      libcurl respects the environment variables http_proxy, ftp_proxy, all_proxy etc, if
	      any  of  those are set. The CURLOPT_PROXY option does however override any possibly
	      set environment variables.

	      Setting the proxy string to "" (an empty string) will explicitly disable the use of
	      a proxy, even if there is an environment variable set for it.

	      Since 7.14.1, the proxy host string given in environment variables can be specified
	      the exact same way as the proxy can be set  with	CURLOPT_PROXY,	include  protocol
	      prefix (http://) and embedded user + password.

	      Since  7.21.7, the proxy string may be specified with a protocol:// prefix to spec-
	      ify alternative proxy protocols. Use socks4://, socks4a://, socks5:// or socks5h://
	      (the last one to enable socks5 and asking the proxy to do the resolving, also known
	      as CURLPROXY_SOCKS5_HOSTNAME type) to request the  specific  SOCKS  version  to  be
	      used.  No  protocol specified, http:// and all others will be treated as HTTP prox-
	      ies.

       CURLOPT_PROXYPORT
	      Pass a long with this option to set the proxy port to connect to unless it is spec-
	      ified in the proxy string CURLOPT_PROXY.

       CURLOPT_PROXYTYPE
	      Pass  a  long with this option to set type of the proxy. Available options for this
	      are CURLPROXY_HTTP, CURLPROXY_HTTP_1_0 (added in 7.19.4),  CURLPROXY_SOCKS4  (added
	      in   7.10),   CURLPROXY_SOCKS5,  CURLPROXY_SOCKS4A  (added  in  7.18.0)  and  CURL-
	      PROXY_SOCKS5_HOSTNAME (added in 7.18.0). The HTTP type is default. (Added in 7.10)

	      If you set CURLOPT_PROXYTYPE to CURLPROXY_HTTP_1_0, it will only affect how libcurl
	      speaks  to  a  proxy when CONNECT is used. The HTTP version used for "regular" HTTP
	      requests is instead controlled with CURLOPT_HTTP_VERSION.

       CURLOPT_NOPROXY
	      Pass a pointer to a zero terminated string. The string consists of  a  comma  sepa-
	      rated list of host names that do not require a proxy to get reached, even if one is
	      specified.  The only wildcard available is a single * character, which matches  all
	      hosts,  and  effectively	disables  the proxy. Each name in this list is matched as
	      either a domain which contains the hostname, or the hostname itself.  For  example,
	      example.com  would  match example.com, example.com:80, and www.example.com, but not
	      www.notanexample.com.  (Added in 7.19.4)

       CURLOPT_HTTPPROXYTUNNEL
	      Set the parameter to 1 to make the library tunnel all operations	through  a  given
	      HTTP  proxy.  There is a big difference between using a proxy and to tunnel through
	      it. If you don't know what this means,  you  probably  don't  want  this	tunneling
	      option.

       CURLOPT_SOCKS5_GSSAPI_SERVICE
	      Pass a char * as parameter to a string holding the name of the service. The default
	      service name for a SOCKS5 server is rcmd/server-fqdn. This  option  allows  you  to
	      change it. (Added in 7.19.4)

       CURLOPT_SOCKS5_GSSAPI_NEC
	      Pass a long set to 1 to enable or 0 to disable. As part of the gssapi negotiation a
	      protection mode is negotiated. The RFC1961 says in section  4.3/4.4  it  should  be
	      protected,  but the NEC reference implementation does not.  If enabled, this option
	      allows the unprotected exchange of  the  protection  mode  negotiation.  (Added  in
	      7.19.4).

       CURLOPT_INTERFACE
	      Pass a char * as parameter. This sets the interface name to use as outgoing network
	      interface. The name can be an interface name, an IP address, or a host name.

	      Starting with 7.24.0: If the parameter starts with "if!" then it is treated as only
	      as interface name and no attempt will ever be named to do treat it as an IP address
	      or to do name resolution on it.  If the parameter starts with "host!" it is treated
	      as  either  an  IP  address  or  a hostname.  Hostnames are resolved synchronously.
	      Using the if! format is highly recommended when using the multi interfaces to avoid
	      allowing the code to block.  If "if!" is specified but the parameter does not match
	      an existing interface, CURLE_INTERFACE_FAILED is returned.

       CURLOPT_LOCALPORT
	      Pass a long. This sets the local port number of the  socket  used  for  connection.
	      This  can  be used in combination with CURLOPT_INTERFACE and you are recommended to
	      use CURLOPT_LOCALPORTRANGE as well when this is set. Valid port  numbers	are  1	-
	      65535. (Added in 7.15.2)

       CURLOPT_LOCALPORTRANGE
	      Pass  a  long.  This  is the number of attempts libcurl will make to find a working
	      local port number. It starts with the given CURLOPT_LOCALPORT and adds one  to  the
	      number for each retry. Setting this to 1 or below will make libcurl do only one try
	      for the exact port number. Port numbers by nature are scarce resources that will be
	      busy  at	times  so setting this value to something too low might cause unnecessary
	      connection setup failures. (Added in 7.15.2)

       CURLOPT_DNS_CACHE_TIMEOUT
	      Pass a long, this sets the timeout in seconds. Name resolves will be kept in memory
	      for this number of seconds. Set to zero to completely disable caching, or set to -1
	      to make the cached entries remain forever. By default, libcurl caches this info for
	      60 seconds.

	      The  name  resolve  functions  of  various  libc implementations don't re-read name
	      server information unless explicitly told so (for example, by calling res_init(3)).
	      This  may cause libcurl to keep using the older server even if DHCP has updated the
	      server info, and this may look like a DNS cache issue  to  the  casual  libcurl-app
	      user.

       CURLOPT_DNS_USE_GLOBAL_CACHE
	      Pass  a  long. If the value is 1, it tells curl to use a global DNS cache that will
	      survive between easy handle creations and deletions. This is  not  thread-safe  and
	      this will use a global variable.

	      WARNING:	this  option  is considered obsolete. Stop using it. Switch over to using
	      the share interface instead! See CURLOPT_SHARE and curl_share_init(3).

       CURLOPT_BUFFERSIZE
	      Pass a long specifying your preferred size (in bytes) for  the  receive  buffer  in
	      libcurl.	 The main point of this would be that the write callback gets called more
	      often and with smaller chunks. This is just treated as a request, not an order. You
	      cannot be guaranteed to actually get the given size. (Added in 7.10)

	      This  size  is  by default set as big as possible (CURL_MAX_WRITE_SIZE), so it only
	      makes sense to use this option if you want it smaller.

       CURLOPT_PORT
	      Pass a long specifying what remote port number to connect to, instead  of  the  one
	      specified in the URL or the default port for the used protocol.

       CURLOPT_TCP_NODELAY
	      Pass  a long specifying whether the TCP_NODELAY option is to be set or cleared (1 =
	      set, 0 = clear). The option is cleared by default. This will have no  effect  after
	      the connection has been established.

	      Setting  this  option will disable TCP's Nagle algorithm. The purpose of this algo-
	      rithm is to try to minimize the number of  small	packets  on  the  network  (where
	      "small packets" means TCP segments less than the Maximum Segment Size (MSS) for the
	      network).

	      Maximizing the amount of data sent per TCP segment is good because it amortizes the
	      overhead	of the send. However, in some cases (most notably telnet or rlogin) small
	      segments may need to be sent without delay. This is  less  efficient  than  sending
	      larger  amounts  of data at a time, and can contribute to congestion on the network
	      if overdone.

       CURLOPT_ADDRESS_SCOPE
	      Pass a long specifying the scope_id value to use when connecting to IPv6 link-local
	      or site-local addresses. (Added in 7.19.0)

       CURLOPT_TCP_KEEPALIVE
	      Pass  a  long.  If  set to 1, TCP keepalive probes will be sent. The delay and fre-
	      quency of these probes can be  controlled  by  the  CURLOPT_TCP_KEEPIDLE	and  CUR-
	      LOPT_TCP_KEEPINTVL  options,  provided the operating system supports them. Set to 0
	      (default behavior) to disable keepalive probes (Added in 7.25.0).

       CURLOPT_TCP_KEEPIDLE
	      Pass a long. Sets the delay, in seconds, that the operating system will wait  while
	      the  connection  is idle before sending keepalive probes. Not all operating systems
	      support this option. (Added in 7.25.0)

       CURLOPT_TCP_KEEPINTVL
	      Pass a long. Sets the interval, in seconds, that the  operating  system  will  wait
	      between  sending	keepalive  probes. Not all operating systems support this option.
	      (Added in 7.25.0)

NAMES and PASSWORDS OPTIONS (Authentication)
       CURLOPT_NETRC
	      This parameter controls the preference of libcurl  between  using  user  names  and
	      passwords  from your ~/.netrc file, relative to user names and passwords in the URL
	      supplied with CURLOPT_URL.

	      libcurl uses a user name (and supplied or prompted  password)  supplied  with  CUR-
	      LOPT_USERPWD in preference to any of the options controlled by this parameter.

	      Pass a long, set to one of the values described below.

	      CURL_NETRC_OPTIONAL
		     The  use of your ~/.netrc file is optional, and information in the URL is to
		     be preferred.  The file will be scanned for the host and user name (to  find
		     the  password  only)  or  for the host only, to find the first user name and
		     password after that machine, which ever information is not specified in  the
		     URL.

		     Undefined values of the option will have this effect.

	      CURL_NETRC_IGNORED
		     The library will ignore the file and use only the information in the URL.

		     This is the default.

	      CURL_NETRC_REQUIRED
		     This value tells the library that use of the file is required, to ignore the
		     information in the URL, and to search the file for the host only.
       Only machine name, user name and password are taken into account (init macros and  similar
       things aren't supported).

       libcurl does not verify that the file has the correct properties set (as the standard Unix
       ftp client does). It should only be readable by user.

       CURLOPT_NETRC_FILE
	      Pass a char * as parameter, pointing to a zero  terminated  string  containing  the
	      full  path  name to the file you want libcurl to use as .netrc file. If this option
	      is omitted, and CURLOPT_NETRC is set, libcurl will attempt to find a .netrc file in
	      the current user's home directory. (Added in 7.10.9)

       CURLOPT_USERPWD
	      Pass  a  char * as parameter, which should be [user name]:[password] to use for the
	      connection. Use CURLOPT_HTTPAUTH to decide the authentication method.

	      When using NTLM, you can set the domain by prepending it to the user name and sepa-
	      rating  the  domain  and	name with a forward (/) or backward slash (\). Like this:
	      "domain/user:password" or "domain\user:password". Some HTTP  servers  (on  Windows)
	      support this style even for Basic authentication.

	      When  using HTTP and CURLOPT_FOLLOWLOCATION, libcurl might perform several requests
	      to possibly different hosts. libcurl will only send this user and password informa-
	      tion  to	hosts  using  the  initial host name (unless CURLOPT_UNRESTRICTED_AUTH is
	      set), so if libcurl follows locations to other hosts it will not send the user  and
	      password to those. This is enforced to prevent accidental information leakage.

       CURLOPT_PROXYUSERPWD
	      Pass  a  char * as parameter, which should be [user name]:[password] to use for the
	      connection to the HTTP proxy.  Use CURLOPT_PROXYAUTH to decide  the  authentication
	      method.

       CURLOPT_USERNAME
	      Pass  a  char  * as parameter, which should be pointing to the zero terminated user
	      name to use for the transfer.

	      CURLOPT_USERNAME sets the user name to be  used  in  protocol  authentication.  You
	      should not use this option together with the (older) CURLOPT_USERPWD option.

	      In  order  to specify the password to be used in conjunction with the user name use
	      the CURLOPT_PASSWORD option.  (Added in 7.19.1)

       CURLOPT_PASSWORD
	      Pass a char * as parameter, which should be pointing to the zero	terminated  pass-
	      word to use for the transfer.

	      The CURLOPT_PASSWORD option should be used in conjunction with the CURLOPT_USERNAME
	      option. (Added in 7.19.1)

       CURLOPT_PROXYUSERNAME
	      Pass a char * as parameter, which should be pointing to the  zero  terminated  user
	      name to use for the transfer while connecting to Proxy.

	      The  CURLOPT_PROXYUSERNAME  option  should be used in same way as the CURLOPT_PROX-
	      YUSERPWD is used.  In comparison to CURLOPT_PROXYUSERPWD the  CURLOPT_PROXYUSERNAME
	      allows   the   username  to  contain  a  colon,  like  in  the  following  example:
	      "sip:user@example.com". The CURLOPT_PROXYUSERNAME option is an alternative  way  to
	      set  the	user  name  while  connecting  to  Proxy.   There is no meaning to use it
	      together with the CURLOPT_PROXYUSERPWD option.

	      In order to specify the password to be used in conjunction with the user	name  use
	      the CURLOPT_PROXYPASSWORD option.  (Added in 7.19.1)

       CURLOPT_PROXYPASSWORD
	      Pass  a  char * as parameter, which should be pointing to the zero terminated pass-
	      word to use for the transfer while connecting to Proxy.

	      The CURLOPT_PROXYPASSWORD option should  be  used  in  conjunction  with	the  CUR-
	      LOPT_PROXYUSERNAME option. (Added in 7.19.1)

       CURLOPT_HTTPAUTH
	      Pass  a long as parameter, which is set to a bitmask, to tell libcurl which authen-
	      tication method(s) you want it to use. The available bits are listed below. If more
	      than  one bit is set, libcurl will first query the site to see which authentication
	      methods it supports and then pick the best one you allow it to use. For some  meth-
	      ods, this will induce an extra network round-trip. Set the actual name and password
	      with the CURLOPT_USERPWD option or with the CURLOPT_USERNAME and the  CURLOPT_PASS-
	      WORD options.  (Added in 7.10.6)

	      CURLAUTH_BASIC
		     HTTP  Basic  authentication. This is the default choice, and the only method
		     that is in wide-spread use and supported virtually  everywhere.  This  sends
		     the  user	name and password over the network in plain text, easily captured
		     by others.

	      CURLAUTH_DIGEST
		     HTTP Digest authentication.  Digest authentication is defined in RFC2617 and
		     is a more secure way to do authentication over public networks than the reg-
		     ular old-fashioned Basic method.

	      CURLAUTH_DIGEST_IE
		     HTTP Digest authentication with an  IE  flavor.   Digest  authentication  is
		     defined in RFC2617 and is a more secure way to do authentication over public
		     networks than the regular old-fashioned Basic method. The IE flavor is  sim-
		     ply  that	libcurl  will use a special "quirk" that IE is known to have used
		     before version 7 and that some servers require  the  client  to  use.  (This
		     define was added in 7.19.3)

	      CURLAUTH_GSSNEGOTIATE
		     HTTP  GSS-Negotiate  authentication.  The GSS-Negotiate (also known as plain
		     "Negotiate") method was designed by Microsoft  and  is  used  in  their  web
		     applications.  It	is primarily meant as a support for Kerberos5 authentica-
		     tion but may also be used along with other authentication methods. For  more
		     information see IETF draft draft-brezak-spnego-http-04.txt.

		     You need to build libcurl with a suitable GSS-API library for this to work.

	      CURLAUTH_NTLM
		     HTTP NTLM authentication. A proprietary protocol invented and used by Micro-
		     soft. It uses a challenge-response and hash concept similar  to  Digest,  to
		     prevent the password from being eavesdropped.

		     You  need	to  build  libcurl with either OpenSSL, GnuTLS or NSS support for
		     this option to work, or build libcurl on Windows.

	      CURLAUTH_NTLM_WB
		     NTLM delegating to winbind helper. Authentication is performed by a separate
		     binary application that is executed when needed. The name of the application
		     is specified at compile time but is typically /usr/bin/ntlm_auth  (Added  in
		     7.22.0)

		     Note  that  libcurl  will fork when necessary to run the winbind application
		     and kill it when complete, calling waitpid() to await its exit when done. On
		     POSIX  operating systems, killing the process will cause a SIGCHLD signal to
		     be raised (regardless of whether CURLOPT_NOSIGNAL is  set),  which  must  be
		     handled  intelligently  by  the  application. In particular, the application
		     must not unconditionally call wait() in its SIGCHLD signal handler to  avoid
		     being  subject  to  a race condition.  This behavior is subject to change in
		     future versions of libcurl.

	      CURLAUTH_ANY
		     This is a convenience macro that sets all bits and thus makes  libcurl  pick
		     any  it  finds  suitable. libcurl will automatically select the one it finds
		     most secure.

	      CURLAUTH_ANYSAFE
		     This is a convenience macro that sets all bits except Basic and  thus  makes
		     libcurl  pick  any  it finds suitable. libcurl will automatically select the
		     one it finds most secure.

	      CURLAUTH_ONLY
		     This is a meta symbol. Or this value together with a  single  specific  auth
		     value to force libcurl to probe for un-restricted auth and if not, only that
		     single auth algorithm is acceptable. (Added in 7.21.3)

       CURLOPT_TLSAUTH_TYPE
	      Pass a long as parameter, which is set to a bitmask, to tell libcurl which  authen-
	      tication method(s) you want it to use for TLS authentication.

	      CURLOPT_TLSAUTH_SRP
		     TLS-SRP  authentication.  Secure  Remote  Password authentication for TLS is
		     defined in RFC5054 and provides mutual authentication if both sides  have	a
		     shared  secret.  To use TLS-SRP, you must also set the CURLOPT_TLSAUTH_USER-
		     NAME and CURLOPT_TLSAUTH_PASSWORD options.

		     You need to build libcurl with GnuTLS or OpenSSL with  TLS-SRP  support  for
		     this to work. (Added in 7.21.4)

       CURLOPT_TLSAUTH_USERNAME
	      Pass  a  char * as parameter, which should point to the zero terminated username to
	      use for the TLS  authentication  method  specified  with	the  CURLOPT_TLSAUTH_TYPE
	      option.  Requires  that  the  CURLOPT_TLS_PASSWORD  option  also	be set. (Added in
	      7.21.4)

       CURLOPT_TLSAUTH_PASSWORD
	      Pass a char * as parameter, which should point to the zero terminated  password  to
	      use  for	the  TLS  authentication  method  specified with the CURLOPT_TLSAUTH_TYPE
	      option. Requires that the  CURLOPT_TLS_USERNAME  option  also  be  set.  (Added  in
	      7.21.4)

       CURLOPT_PROXYAUTH
	      Pass  a long as parameter, which is set to a bitmask, to tell libcurl which authen-
	      tication method(s) you want it to use for your proxy authentication.  If more  than
	      one  bit is set, libcurl will first query the site to see what authentication meth-
	      ods it supports and then pick the best one you allow it to use. For  some  methods,
	      this will induce an extra network round-trip. Set the actual name and password with
	      the CURLOPT_PROXYUSERPWD option. The bitmask can be constructed by or'ing  together
	      the  bits  listed  above	for the CURLOPT_HTTPAUTH option. As of this writing, only
	      Basic, Digest and NTLM work. (Added in 7.10.7)

HTTP OPTIONS
       CURLOPT_AUTOREFERER
	      Pass a parameter set to 1 to enable this. When enabled, libcurl will  automatically
	      set the Referer: field in requests where it follows a Location: redirect.

       CURLOPT_ACCEPT_ENCODING
	      Sets  the  contents  of  the  Accept-Encoding:  header  sent in a HTTP request, and
	      enables decoding of a response when a Content-Encoding: header is received.   Three
	      encodings  are  supported: identity, which does nothing, deflate which requests the
	      server to compress its response using the zlib algorithm, and gzip  which  requests
	      the  gzip  algorithm.   If  a  zero-length  string is set, then an Accept-Encoding:
	      header containing all supported encodings is sent.

	      This is a request, not an order; the server may or may not do it.  This option must
	      be  set (to any non-NULL value) or else any unsolicited encoding done by the server
	      is ignored. See the special file lib/README.encoding for details.

	      (This option was called CURLOPT_ENCODING before 7.21.6)

       CURLOPT_TRANSFER_ENCODING
	      Adds a request for compressed Transfer Encoding in the outgoing  HTTP  request.  If
	      the server supports this and so desires, it can respond with the HTTP response sent
	      using a compressed Transfer-Encoding that will  be  automatically  uncompressed  by
	      libcurl on reception.

	      Transfer-Encoding  differs slightly from the Content-Encoding you ask for with CUR-
	      LOPT_ACCEPT_ENCODING in that a Transfer-Encoding is strictly meant to  be  for  the
	      transfer and thus MUST be decoded before the data arrives in the client. Tradition-
	      ally, Transfer-Encoding has been much less used and supported by both HTTP  clients
	      and HTTP servers.

	      (Added in 7.21.6)

       CURLOPT_FOLLOWLOCATION
	      A  parameter  set  to  1	tells the library to follow any Location: header that the
	      server sends as part of a HTTP header.

	      This means that the library will re-send the same request on the new  location  and
	      follow  new  Location: headers all the way until no more such headers are returned.
	      CURLOPT_MAXREDIRS can be used to limit the number of redirects libcurl will follow.

	      Since 7.19.4, libcurl can limit what protocols it will  automatically  follow.  The
	      accepted	protocols  are	set with CURLOPT_REDIR_PROTOCOLS and it excludes the FILE
	      protocol by default.

       CURLOPT_UNRESTRICTED_AUTH
	      A parameter set to 1 tells the library  it  can  continue  to  send  authentication
	      (user+password)  when  following locations, even when hostname changed. This option
	      is meaningful only when setting CURLOPT_FOLLOWLOCATION.

       CURLOPT_MAXREDIRS
	      Pass a long. The set number will be the redirection limit. If  that  many  redirec-
	      tions   have   been   followed,	the   next   redirect	will   cause   an   error
	      (CURLE_TOO_MANY_REDIRECTS). This option only makes sense if the CURLOPT_FOLLOWLOCA-
	      TION  is	used  at the same time. Added in 7.15.1: Setting the limit to 0 will make
	      libcurl refuse any redirect. Set it to -1  for  an  infinite  number  of	redirects
	      (which is the default)

       CURLOPT_POSTREDIR
	      Pass a bitmask to control how libcurl acts on redirects after POSTs that get a 301,
	      302 or 303 response back.  A parameter with bit 0 set  (value  CURL_REDIR_POST_301)
	      tells  the library to respect RFC2616/10.3.2 and not convert POST requests into GET
	      requests	 when	following   a	301   redirection.    Setting	bit   1    (value
	      CURL_REDIR_POST_302) makes libcurl maintain the request method after a 302 redirect
	      whilst setting bit 2 (value CURL_REDIR_POST_303) makes libcurl maintain the request
	      method  after a 303 redirect. The value CURL_REDIR_POST_ALL is a convenience define
	      that sets all three bits.

	      The non-RFC behaviour is ubiquitous in web browsers, so the library does	the  con-
	      version by default to maintain consistency. However, a server may require a POST to
	      remain a POST after such a redirection. This option is meaningful only when setting
	      CURLOPT_FOLLOWLOCATION.	 (Added  in  7.17.1)  (This  option  was  known  as  CUR-
	      LOPT_POST301 up to 7.19.0 as it only supported the 301 then)

       CURLOPT_PUT
	      A parameter set to 1 tells the library to use HTTP PUT to transfer data.	The  data
	      should be set with CURLOPT_READDATA and CURLOPT_INFILESIZE.

	      This  option  is deprecated and starting with version 7.12.1 you should instead use
	      CURLOPT_UPLOAD.

       CURLOPT_POST
	      A parameter set to 1 tells the library to do a regular HTTP post.  This  will  also
	      make  the  library  use a "Content-Type: application/x-www-form-urlencoded" header.
	      (This is by far the most commonly used POST method).

	      Use one of CURLOPT_POSTFIELDS or CURLOPT_COPYPOSTFIELDS  options	to  specify  what
	      data  to	post  and CURLOPT_POSTFIELDSIZE or CURLOPT_POSTFIELDSIZE_LARGE to set the
	      data size.

	      Optionally, you can provide data to POST using the  CURLOPT_READFUNCTION	and  CUR-
	      LOPT_READDATA  options but then you must make sure to not set CURLOPT_POSTFIELDS to
	      anything but NULL. When providing data with a callback, you must transmit it  using
	      chunked  transfer-encoding  or  you  must  set  the  size of the data with the CUR-
	      LOPT_POSTFIELDSIZE or CURLOPT_POSTFIELDSIZE_LARGE option. To enable chunked  encod-
	      ing,  you  simply  pass  in the appropriate Transfer-Encoding header, see the post-
	      callback.c example.

	      You can override the default POST Content-Type: header by  setting  your	own  with
	      CURLOPT_HTTPHEADER.

	      Using  POST  with HTTP 1.1 implies the use of a "Expect: 100-continue" header.  You
	      can disable this header with CURLOPT_HTTPHEADER as usual.

	      If you use POST to a HTTP 1.1 server, you can send data without  knowing	the  size
	      before  starting	the POST if you use chunked encoding. You enable this by adding a
	      header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER. With HTTP 1.0  or
	      without chunked transfer, you must specify the size in the request.

	      When  setting  CURLOPT_POST  to  1,  it  will automatically set CURLOPT_NOBODY to 0
	      (since 7.14.1).

	      If you issue a POST request and then want to make a HEAD or GET using the same  re-
	      used  handle,  you must explicitly set the new request type using CURLOPT_NOBODY or
	      CURLOPT_HTTPGET or similar.

       CURLOPT_POSTFIELDS
	      Pass a void * as parameter, which should be the full data to post in  a  HTTP  POST
	      operation.  You  must  make  sure  that  the data is formatted the way you want the
	      server to receive it. libcurl will not convert or  encode  it  for  you.	Most  web
	      servers will assume this data to be url-encoded.

	      The pointed data are NOT copied by the library: as a consequence, they must be pre-
	      served by the calling application until the transfer finishes.

	      This POST is a normal application/x-www-form-urlencoded kind (and libcurl will  set
	      that  Content-Type by default when this option is used), which is the most commonly
	      used one by HTML forms. See also the CURLOPT_POST. Using CURLOPT_POSTFIELDS implies
	      CURLOPT_POST.

	      If  you  want to do a zero-byte POST, you need to set CURLOPT_POSTFIELDSIZE explic-
	      itly to zero, as simply setting CURLOPT_POSTFIELDS to NULL or ""	just  effectively
	      disables	the  sending  of  the  specified string. libcurl will instead assume that
	      you'll send the POST data using the read callback!

	      Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue"  header.   You
	      can disable this header with CURLOPT_HTTPHEADER as usual.

	      To  make	multipart/formdata posts (aka RFC2388-posts), check out the CURLOPT_HTTP-
	      POST option.

       CURLOPT_POSTFIELDSIZE
	      If you want to post data to the server without letting libcurl  do  a  strlen()  to
	      measure  the  data size, this option must be used. When this option is used you can
	      post fully binary data, which otherwise is likely to fail. If this size is  set  to
	      -1, the library will use strlen() to get the size.

       CURLOPT_POSTFIELDSIZE_LARGE
	      Pass  a curl_off_t as parameter. Use this to set the size of the CURLOPT_POSTFIELDS
	      data to prevent libcurl from doing strlen() on the data to  figure  out  the  size.
	      This  is	the  large  file  version  of the CURLOPT_POSTFIELDSIZE option. (Added in
	      7.11.1)

       CURLOPT_COPYPOSTFIELDS
	      Pass a char * as parameter, which should be the full data to post in  a  HTTP  POST
	      operation.  It  behaves as the CURLOPT_POSTFIELDS option, but the original data are
	      copied by the library, allowing the application  to  overwrite  the  original  data
	      after setting this option.

	      Because  data  are copied, care must be taken when using this option in conjunction
	      with CURLOPT_POSTFIELDSIZE or CURLOPT_POSTFIELDSIZE_LARGE: If the size has not been
	      set  prior  to  CURLOPT_COPYPOSTFIELDS, the data are assumed to be a NUL-terminated
	      string; else the stored size informs the library about the data byte count to copy.
	      In  any  case,  the  size  must not be changed after CURLOPT_COPYPOSTFIELDS, unless
	      another CURLOPT_POSTFIELDS or CURLOPT_COPYPOSTFIELDS option is issued.   (Added  in
	      7.17.1)

       CURLOPT_HTTPPOST
	      Tells  libcurl  you want a multipart/formdata HTTP POST to be made and you instruct
	      what data to pass on to the server.  Pass a pointer to a linked list of  curl_http-
	      post  structs  as  parameter.   The  easiest  way  to create such a list, is to use
	      curl_formadd(3) as documented. The data in this list must remain intact  until  you
	      close this curl handle again with curl_easy_cleanup(3).

	      Using  POST  with HTTP 1.1 implies the use of a "Expect: 100-continue" header.  You
	      can disable this header with CURLOPT_HTTPHEADER as usual.

	      When setting CURLOPT_HTTPPOST, it will automatically set CURLOPT_NOBODY to 0 (since
	      7.14.1).

       CURLOPT_REFERER
	      Pass a pointer to a zero terminated string as parameter. It will be used to set the
	      Referer: header in the http request sent to the remote server. This can be used  to
	      fool  servers  or  scripts.  You	can also set any custom header with CURLOPT_HTTP-
	      HEADER.

       CURLOPT_USERAGENT
	      Pass a pointer to a zero terminated string as parameter. It will be used to set the
	      User-Agent:  header in the http request sent to the remote server. This can be used
	      to fool servers or scripts. You can also set any custom header  with  CURLOPT_HTTP-
	      HEADER.

       CURLOPT_HTTPHEADER
	      Pass  a pointer to a linked list of HTTP headers to pass to the server in your HTTP
	      request. The linked list should be a fully valid list of struct curl_slist  structs
	      properly	 filled   in.	Use   curl_slist_append(3)   to   create   the	list  and
	      curl_slist_free_all(3) to clean up an entire list. If you add a header that is oth-
	      erwise  generated  and  used  by	libcurl  internally,  your added one will be used
	      instead. If you add a header with no content as in 'Accept:' (no data on the  right
	      side  of the colon), the internally used header will get disabled. Thus, using this
	      option you can add new headers, replace internal headers and remove internal  head-
	      ers. To add a header with no content, make the content be two quotes: "". The head-
	      ers included in the linked list must not be CRLF-terminated, because curl adds CRLF
	      after  each  header  item.  Failure to comply with this will result in strange bugs
	      because the server will most likely ignore part of the headers you specified.

	      The first line in a request (containing the method, usually a GET or POST) is not a
	      header  and  cannot  be  replaced  using	this option. Only the lines following the
	      request-line are headers. Adding this method line in this list of headers will only
	      cause your request to send an invalid header.

	      Pass a NULL to this to reset back to no custom headers.

	      The  most commonly replaced headers have "shortcuts" in the options CURLOPT_COOKIE,
	      CURLOPT_USERAGENT and CURLOPT_REFERER.

       CURLOPT_HTTP200ALIASES
	      Pass a pointer to a linked list  of  aliases  to	be  treated  as  valid	HTTP  200
	      responses.   Some servers respond with a custom header response line.  For example,
	      IceCast servers respond with "ICY 200 OK".  By including this string in  your  list
	      of  aliases,  the  response  will  be  treated  as a valid HTTP header line such as
	      "HTTP/1.0 200 OK". (Added in 7.10.3)

	      The linked list should be a fully valid list of struct curl_slist structs,  and  be
	      properly	 filled   in.	 Use   curl_slist_append(3)   to   create  the	list  and
	      curl_slist_free_all(3) to clean up an entire list.

	      The alias itself is not parsed for any  version  strings.  Before  libcurl  7.16.3,
	      Libcurl used the value set by option CURLOPT_HTTP_VERSION, but starting with 7.16.3
	      the protocol is assumed to match HTTP 1.0 when an alias matched.

       CURLOPT_COOKIE
	      Pass a pointer to a zero terminated string as parameter. It will be used to  set	a
	      cookie in the http request. The format of the string should be NAME=CONTENTS, where
	      NAME is the cookie name and CONTENTS is what the cookie should contain.

	      If you need to set multiple cookies, you need to set them all using a single option
	      and  thus you need to concatenate them all in one single string. Set multiple cook-
	      ies in one string like this: "name1=content1; name2=content2;" etc.

	      This option sets the cookie header explicitly in the outgoing request(s). If multi-
	      ple requests are done due to authentication, followed redirections or similar, they
	      will all get this cookie passed on.

	      Using this option multiple times will only make the latest string override the pre-
	      vious ones.

       CURLOPT_COOKIEFILE
	      Pass a pointer to a zero terminated string as parameter. It should contain the name
	      of your file holding cookie data to read. The cookie data  may  be  in  Netscape	/
	      Mozilla cookie data format or just regular HTTP-style headers dumped to a file.

	      Given  an  empty	or  non-existing  file	or by passing the empty string (""), this
	      option will enable cookies for this curl handle, making  it  understand  and  parse
	      received cookies and then use matching cookies in future requests.

	      If you use this option multiple times, you just add more files to read.  Subsequent
	      files will add more cookies.

       CURLOPT_COOKIEJAR
	      Pass a file name as char *, zero terminated.  This  will	make  libcurl  write  all
	      internally known cookies to the specified file when curl_easy_cleanup(3) is called.
	      If no cookies are known, no file will be created. Specify "-" to instead	have  the
	      cookies written to stdout. Using this option also enables cookies for this session,
	      so if you for example follow a location it will  make  matching  cookies	get  sent
	      accordingly.

	      If   the	 cookie   jar	file   can't   be   created   or  written  to  (when  the
	      curl_easy_cleanup(3) is called), libcurl will not and cannot report  an  error  for
	      this. Using CURLOPT_VERBOSE or CURLOPT_DEBUGFUNCTION will get a warning to display,
	      but that is the only visible feedback you get about this possibly lethal situation.

       CURLOPT_COOKIESESSION
	      Pass a long set to 1 to mark this as a new cookie "session". It will force  libcurl
	      to  ignore all cookies it is about to load that are "session cookies" from the pre-
	      vious session. By default, libcurl always stores and loads all cookies, independent
	      if they are session cookies or not. Session cookies are cookies without expiry date
	      and they are meant to be alive and existing for this "session" only.

       CURLOPT_COOKIELIST
	      Pass a char * to a cookie string. Cookie can be either in Netscape / Mozilla format
	      or  just	regular HTTP-style header (Set-Cookie: ...) format. If cURL cookie engine
	      was not enabled it will enable its cookie engine.  Passing  a  magic  string  "ALL"
	      will  erase all cookies known by cURL. (Added in 7.14.1) Passing the special string
	      "SESS" will only erase all session cookies known by cURL. (Added in 7.15.4) Passing
	      the  special string "FLUSH" will write all cookies known by cURL to the file speci-
	      fied by CURLOPT_COOKIEJAR.  (Added in 7.17.1)

       CURLOPT_HTTPGET
	      Pass a long. If the long is 1, this forces the HTTP request to  get  back  to  GET.
	      Usable if a POST, HEAD, PUT, or a custom request has been used previously using the
	      same curl handle.

	      When setting CURLOPT_HTTPGET to 1, it will automatically set  CURLOPT_NOBODY  to	0
	      (since 7.14.1).

       CURLOPT_HTTP_VERSION
	      Pass  a  long,  set to one of the values described below. They force libcurl to use
	      the specific HTTP versions. This is not sensible to do unless you have a good  rea-
	      son.

	      CURL_HTTP_VERSION_NONE
		     We don't care about what version the library uses. libcurl will use whatever
		     it thinks fit.

	      CURL_HTTP_VERSION_1_0
		     Enforce HTTP 1.0 requests.

	      CURL_HTTP_VERSION_1_1
		     Enforce HTTP 1.1 requests.

       CURLOPT_IGNORE_CONTENT_LENGTH
	      Ignore the Content-Length header. This  is  useful  for  Apache  1.x  (and  similar
	      servers)	which will report incorrect content length for files over 2 gigabytes. If
	      this option is used, curl will not be able to accurately report progress, and  will
	      simply stop the download when the server ends the connection. (added in 7.14.1)

       CURLOPT_HTTP_CONTENT_DECODING
	      Pass a long to tell libcurl how to act on content decoding. If set to zero, content
	      decoding will be disabled. If set to 1 it is enabled. Libcurl has no  default  con-
	      tent decoding but requires you to use CURLOPT_ENCODING for that. (added in 7.16.2)

       CURLOPT_HTTP_TRANSFER_DECODING
	      Pass a long to tell libcurl how to act on transfer decoding. If set to zero, trans-
	      fer decoding will be disabled, if set to 1 it is enabled	(default).  libcurl  does
	      chunked  transfer  decoding by default unless this option is set to zero. (added in
	      7.16.2)

SMTP OPTIONS
       CURLOPT_MAIL_FROM
	      Pass a pointer to a zero terminated string as parameter. This  should  be  used  to
	      specify the sender's email address when sending SMTP mail with libcurl.

	      An  originator  email  address should be specified with angled brackets (<>) around
	      it, which if not specified, will be added by libcurl from version  7.21.4  onwards.
	      Failing to provide such brackets may cause the server to reject the email.

	      If  this	parameter is not specified then an empty address will be sent to the mail
	      server which may or may not cause the email to be rejected.

	      (Added in 7.20.0)

       CURLOPT_MAIL_RCPT
	      Pass a pointer to a linked list of recipients to pass to the server  in  your  SMTP
	      mail  request.  The  linked  list should be a fully valid list of struct curl_slist
	      structs properly filled  in.  Use  curl_slist_append(3)  to  create  the	list  and
	      curl_slist_free_all(3) to clean up an entire list.

	      Each  recipient should be specified within a pair of angled brackets (<>), however,
	      should you not use an angled bracket as the first character libcurl will assume you
	      provided a single email address and enclose that address within brackets for you.

	      (Added in 7.20.0)

       CURLOPT_MAIL_AUTH
	      Pass a pointer to a zero terminated string as parameter. This will be used to spec-
	      ify the authentication address (identity) of a  submitted  message  that	is  being
	      relayed to another server.

	      This optional parameter allows co-operating agents in a trusted environment to com-
	      municate the authentication of individual messages and should only be used  by  the
	      application program, using libcurl, if the application is itself a mail server act-
	      ing in such an environment. If the application is operating as such  and	the  AUTH
	      address  is  not	known or is invalid, then an empty string should be used for this
	      parameter.

	      Unlike CURLOPT_MAIL_FROM and CURLOPT_MAIL_RCPT, the address should not be specified
	      within  a  pair of angled brackets (<>). However, if an empty string is used then a
	      pair of brackets will be sent by libcurl as required by RFC2554.

	      (Added in 7.25.0)

TFTP OPTIONS
       CURLOPT_TFTP_BLKSIZE
	      Specify block size to use for TFTP data transmission. Valid range as per RFC2348 is
	      8-65464  bytes.  The default of 512 bytes will be used if this option is not speci-
	      fied. The specified block size will only be used	pending  support  by  the  remote
	      server.  If  the	server	does  not  return an option acknowledgement or returns an
	      option acknowledgement with no blksize, the default of  512  bytes  will	be  used.
	      (added in 7.19.4)

FTP OPTIONS
       CURLOPT_FTPPORT
	      Pass a pointer to a zero terminated string as parameter. It will be used to get the
	      IP address to use for the FTP PORT instruction.  The  PORT  instruction  tells  the
	      remote  server to connect to our specified IP address. The string may be a plain IP
	      address, a host name, a network interface name (under Unix) or just a '-' symbol to
	      let  the	library  use your system's default IP address. Default FTP operations are
	      passive, and thus won't use PORT.

	      The address can be followed by a ':' to specify a port, optionally  followed  by	a
	      '-' to specify a port range.  If the port specified is 0, the operating system will
	      pick a free port.  If a range is provided and all ports in the range are not avail-
	      able, libcurl will report CURLE_FTP_PORT_FAILED for the handle.  Invalid port/range
	      settings are ignored.  IPv6 addresses followed by a port or portrange have to be in
	      brackets.   IPv6 addresses without port/range specifier can be in brackets.  (added
	      in 7.19.5)

	      Examples with specified ports:

		eth0:0
		192.168.1.2:32000-33000
		curl.se:32123
		[::1]:1234-4567

	      You disable PORT again and go back to using the passive  version	by  setting  this
	      option to NULL.

       CURLOPT_QUOTE
	      Pass a pointer to a linked list of FTP or SFTP commands to pass to the server prior
	      to your FTP request. This will be done before any other commands are  issued  (even
	      before  the  CWD	command for FTP). The linked list should be a fully valid list of
	      'struct  curl_slist'  structs  properly  filled	in   with   text   strings.   Use
	      curl_slist_append(3) to append strings (commands) to the list, and clear the entire
	      list afterwards with curl_slist_free_all(3). Disable this operation again  by  set-
	      ting  a  NULL to this option. When speaking to a FTP (or SFTP since 7.24.0) server,
	      prefix the command with an asterisk (*) to make libcurl continue even if	the  com-
	      mand fails as by default libcurl will stop at first failure.

	      The  set	of  valid  FTP	commands  depends on the server (see RFC959 for a list of
	      mandatory commands).

	      The valid SFTP commands are: chgrp, chmod,  chown,  ln,  mkdir,  pwd,  rename,  rm,
	      rmdir, symlink (see curl(1)) (SFTP support added in 7.16.3)

       CURLOPT_POSTQUOTE
	      Pass a pointer to a linked list of FTP or SFTP commands to pass to the server after
	      your FTP transfer request. The commands will only be run if no error occurred.  The
	      linked  list  should  be	a  fully valid list of struct curl_slist structs properly
	      filled in as described for CURLOPT_QUOTE. Disable this operation again by setting a
	      NULL to this option.

       CURLOPT_PREQUOTE
	      Pass  a  pointer	to  a linked list of FTP commands to pass to the server after the
	      transfer type is set. The linked list should  be	a  fully  valid  list  of  struct
	      curl_slist  structs properly filled in as described for CURLOPT_QUOTE. Disable this
	      operation again by setting a NULL to this option. Before	version  7.16.0,  if  you
	      also set CURLOPT_NOBODY to 1, this option didn't work.

       CURLOPT_DIRLISTONLY
	      A  parameter set to 1 tells the library to just list the names of files in a direc-
	      tory, instead of doing a full directory listing  that  would  include  file  sizes,
	      dates etc. This works for FTP and SFTP URLs.

	      This  causes an FTP NLST command to be sent on an FTP server.  Beware that some FTP
	      servers list only files in their response to NLST; they might not include subdirec-
	      tories and symbolic links.

	      Setting  this  option to 1 also implies a directory listing even if the URL doesn't
	      end with a slash, which otherwise is necessary.

	      Do NOT use this option if you also use CURLOPT_WILDCARDMATCH as it will effectively
	      break that feature then.

	      (This option was known as CURLOPT_FTPLISTONLY up to 7.16.4)

       CURLOPT_APPEND
	      A  parameter  set  to  1	tells the library to append to the remote file instead of
	      overwrite it. This is only useful when uploading to an FTP site.

	      (This option was known as CURLOPT_FTPAPPEND up to 7.16.4)

       CURLOPT_FTP_USE_EPRT
	      Pass a long. If the value is 1, it tells curl to use the EPRT  (and  LPRT)  command
	      when  doing  active FTP downloads (which is enabled by CURLOPT_FTPPORT). Using EPRT
	      means that it will first attempt to use EPRT and then LPRT before using  PORT,  but
	      if  you  pass  zero  to this option, it will not try using EPRT or LPRT, only plain
	      PORT. (Added in 7.10.5)

	      If the server is an IPv6 host, this option will have no effect as of 7.12.3.

       CURLOPT_FTP_USE_EPSV
	      Pass a long. If the value is 1, it tells curl to use the EPSV  command  when  doing
	      passive  FTP  downloads (which it always does by default). Using EPSV means that it
	      will first attempt to use EPSV before using PASV, but if	you  pass  zero  to  this
	      option, it will not try using EPSV, only plain PASV.

	      If the server is an IPv6 host, this option will have no effect as of 7.12.3.

       CURLOPT_FTP_USE_PRET
	      Pass  a  long.  If the value is 1, it tells curl to send a PRET command before PASV
	      (and EPSV). Certain FTP servers, mainly drftpd, require this  non-standard  command
	      for directory listings as well as up and downloads in PASV mode. Has no effect when
	      using the active FTP transfers mode.  (Added in 7.20.0)

       CURLOPT_FTP_CREATE_MISSING_DIRS
	      Pass a long. If the value is 1, curl will attempt to create  any	remote	directory
	      that  it	fails  to  CWD	into.  CWD is the command that changes working directory.
	      (Added in 7.10.7)

	      This setting also applies to SFTP-connections. curl  will  attempt  to  create  the
	      remote  directory  if it can't obtain a handle to the target-location. The creation
	      will fail if a file of the same name as the directory to create already  exists  or
	      lack of permissions prevents creation. (Added in 7.16.3)

	      Starting	with  7.19.4,  you  can also set this value to 2, which will make libcurl
	      retry the CWD command again if the subsequent MKD command fails. This is especially
	      useful  if  you're  doing many simultaneous connections against the same server and
	      they all have this option enabled, as then CWD may first fail but then another con-
	      nection  does  MKD  before this connection and thus MKD fails but trying CWD works!
	      7.19.4 also introduced the  CURLFTP_CREATE_DIR  and  CURLFTP_CREATE_DIR_RETRY  enum
	      names for these arguments.

	      Before  version 7.19.4, libcurl will simply ignore arguments set to 2 and act as if
	      1 was selected.

       CURLOPT_FTP_RESPONSE_TIMEOUT
	      Pass a long.  Causes curl to set a timeout period (in seconds)  on  the  amount  of
	      time that the server is allowed to take in order to generate a response message for
	      a command before the session is considered hung.	 While	curl  is  waiting  for	a
	      response,  this  value overrides CURLOPT_TIMEOUT. It is recommended that if used in
	      conjunction with CURLOPT_TIMEOUT, you set CURLOPT_FTP_RESPONSE_TIMEOUT to  a  value
	      smaller than CURLOPT_TIMEOUT.  (Added in 7.10.8)

       CURLOPT_FTP_ALTERNATIVE_TO_USER
	      Pass a char * as parameter, pointing to a string which will be used to authenticate
	      if the usual FTP "USER user" and "PASS password" negotiation fails.  This  is  cur-
	      rently  only  known to be required when connecting to Tumbleweed's Secure Transport
	      FTPS server using client certificates for authentication. (Added in 7.15.5)

       CURLOPT_FTP_SKIP_PASV_IP
	      Pass a long. If set to 1, it instructs libcurl to not use the IP address the server
	      suggests	in  its  227-response to libcurl's PASV command when libcurl connects the
	      data connection. Instead libcurl will re-use the same IP address	it  already  uses
	      for  the control connection. But it will use the port number from the 227-response.
	      (Added in 7.14.2)

	      This option has no effect if PORT, EPRT or EPSV is used instead of PASV.

       CURLOPT_FTPSSLAUTH
	      Pass a long using one of the values from below, to alter how libcurl  issues  "AUTH
	      TLS"  or "AUTH SSL" when FTP over SSL is activated (see CURLOPT_USE_SSL). (Added in
	      7.12.2)

	      CURLFTPAUTH_DEFAULT
		     Allow libcurl to decide.

	      CURLFTPAUTH_SSL
		     Try "AUTH SSL" first, and only if that fails try "AUTH TLS".

	      CURLFTPAUTH_TLS
		     Try "AUTH TLS" first, and only if that fails try "AUTH SSL".

       CURLOPT_FTP_SSL_CCC
	      If enabled, this option makes libcurl use CCC (Clear  Command  Channel).	It  shuts
	      down the SSL/TLS layer after authenticating. The rest of the control channel commu-
	      nication will be unencrypted. This allows NAT routers to follow  the  FTP  transac-
	      tion. Pass a long using one of the values below.	(Added in 7.16.1)

	      CURLFTPSSL_CCC_NONE
		     Don't attempt to use CCC.

	      CURLFTPSSL_CCC_PASSIVE
		     Do  not initiate the shutdown, but wait for the server to do it. Do not send
		     a reply.

	      CURLFTPSSL_CCC_ACTIVE
		     Initiate the shutdown and wait for a reply.

       CURLOPT_FTP_ACCOUNT
	      Pass a pointer to a zero terminated string (or NULL to disable). When an FTP server
	      asks  for  "account data" after user name and password has been provided, this data
	      is sent off using the ACCT command. (Added in 7.13.0)

       CURLOPT_FTP_FILEMETHOD
	      Pass a long that should have one of the following values. This option controls what
	      method  libcurl  should use to reach a file on a FTP(S) server. The argument should
	      be one of the following alternatives:

	      CURLFTPMETHOD_MULTICWD
		     libcurl does a single CWD operation for each path part in the given URL. For
		     deep  hierarchies	this  means  many  commands.  This is how RFC1738 says it
		     should be done. This is the default but the slowest behavior.

	      CURLFTPMETHOD_NOCWD
		     libcurl does no CWD at all. libcurl will do SIZE, RETR, STOR etc and give	a
		     full  path  to the server for all these commands. This is the fastest behav-
		     ior.

	      CURLFTPMETHOD_SINGLECWD
		     libcurl does one CWD with the full target directory and then operates on the
		     file "normally" (like in the multicwd case). This is somewhat more standards
		     compliant than 'nocwd' but without the full penalty of 'multicwd'.
       (Added in 7.15.1)

RTSP OPTIONS
       CURLOPT_RTSP_REQUEST
	      Tell libcurl what kind of RTSP request to make. Pass one of the following RTSP enum
	      values.  Unless noted otherwise, commands require the Session ID to be initialized.
	      (Added in 7.20.0)

	      CURL_RTSPREQ_OPTIONS
		     Used to retrieve the available methods of the  server.  The  application  is
		     responsible  for  parsing	and  obeying the response. (The session ID is not
		     needed for this method.)  (Added in 7.20.0)

	      CURL_RTSPREQ_DESCRIBE
		     Used to get the low level description of a stream.  The  application  should
		     note  what  formats it understands in the 'Accept:' header. Unless set manu-
		     ally, libcurl will automatically fill in  'Accept:  application/sdp'.  Time-
		     condition headers will be added to Describe requests if the CURLOPT_TIMECON-
		     DITION option is active. (The session ID is  not  needed  for  this  method)
		     (Added in 7.20.0)

	      CURL_RTSPREQ_ANNOUNCE
		     When  sent  by a client, this method changes the description of the session.
		     For example, if a client is using the server to record a meeting, the client
		     can  use Announce to inform the server of all the meta-information about the
		     session.	ANNOUNCE   acts   like	 a   HTTP   PUT   or   POST   just   like
		     CURL_RTSPREQ_SET_PARAMETER (Added in 7.20.0)

	      CURL_RTSPREQ_SETUP
		     Setup  is used to initialize the transport layer for the session. The appli-
		     cation must set the desired Transport options for a  session  by  using  the
		     CURLOPT_RTSP_TRANSPORT  option  prior  to calling setup. If no session ID is
		     currently set with CURLOPT_RTSP_SESSION_ID, libcurl will extract and use the
		     session  ID  in  the response to this request. (The session ID is not needed
		     for this method).	(Added in 7.20.0)

	      CURL_RTSPREQ_PLAY
		     Send a Play command to the server. Use the CURLOPT_RANGE  option  to  modify
		     the playback time (e.g. 'npt=10-15').  (Added in 7.20.0)

	      CURL_RTSPREQ_PAUSE
		     Send a Pause command to the server. Use the CURLOPT_RANGE option with a sin-
		     gle value to indicate when the stream  should  be	halted.  (e.g.	npt='25')
		     (Added in 7.20.0)

	      CURL_RTSPREQ_TEARDOWN
		     This  command  terminates	an RTSP session. Simply closing a connection does
		     not terminate the RTSP session since it is valid to control an RTSP  session
		     over different connections.  (Added in 7.20.0)

	      CURL_RTSPREQ_GET_PARAMETER
		     Retrieve a parameter from the server. By default, libcurl will automatically
		     include a Content-Type: text/parameters header  on  all  non-empty  requests
		     unless  a custom one is set. GET_PARAMETER acts just like a HTTP PUT or POST
		     (see CURL_RTSPREQ_SET_PARAMETER).	Applications wishing to send a	heartbeat
		     message (e.g. in the presence of a server-specified timeout) should send use
		     an empty GET_PARAMETER request.  (Added in 7.20.0)

	      CURL_RTSPREQ_SET_PARAMETER
		     Set a parameter on  the  server.  By  default,  libcurl  will  automatically
		     include  a  Content-Type: text/parameters header unless a custom one is set.
		     The interaction with SET_PARAMTER is much like a HTTP PUT or POST. An appli-
		     cation  may either use CURLOPT_UPLOAD with CURLOPT_READDATA like a HTTP PUT,
		     or it may use CURLOPT_POSTFIELDS like a HTTP POST. No chunked transfers  are
		     allowed,  so  the	application must set the CURLOPT_INFILESIZE in the former
		     and CURLOPT_POSTFIELDSIZE in the latter. Also, there is no use of multi-part
		     POSTs within RTSP. (Added in 7.20.0)

	      CURL_RTSPREQ_RECORD
		     Used to tell the server to record a session. Use the CURLOPT_RANGE option to
		     modify the record time. (Added in 7.20.0)

	      CURL_RTSPREQ_RECEIVE
		     This is a special request because it does not send any data to  the  server.
		     The  application  may call this function in order to receive interleaved RTP
		     data. It will return after processing one read buffer of data  in	order  to
		     give the application a chance to run. (Added in 7.20.0)

       CURLOPT_RTSP_SESSION_ID
	      Pass  a  char  * as a parameter to set the value of the current RTSP Session ID for
	      the handle. Useful for resuming an in-progress session. Once this value is  set  to
	      any  non-NULL  value,  libcurl  will return CURLE_RTSP_SESSION_ERROR if ID received
	      from the server does not match. If unset (or set to NULL), libcurl  will	automati-
	      cally set the ID the first time the server sets it in a response. (Added in 7.20.0)

       CURLOPT_RTSP_STREAM_URI
	      Set  the	stream URI to operate on by passing a char * . For example, a single ses-
	      sion may be controlling rtsp://foo/twister/audio and  rtsp://foo/twister/video  and
	      the  application	can switch to the appropriate stream using this option. If unset,
	      libcurl will default to operating on generic server options by passing '*'  in  the
	      place  of the RTSP Stream URI. This option is distinct from CURLOPT_URL. When work-
	      ing with RTSP, the CURLOPT_STREAM_URI indicates what URL to send to the  server  in
	      the request header while the CURLOPT_URL indicates where to make the connection to.
	      (e.g. the CURLOPT_URL for the above examples might  be  set  to  rtsp://foo/twister
	      (Added in 7.20.0)

       CURLOPT_RTSP_TRANSPORT
	      Pass  a char * to tell libcurl what to pass for the Transport: header for this RTSP
	      session. This is mainly a convenience method to  avoid  needing  to  set	a  custom
	      Transport:  header  for  every SETUP request. The application must set a Transport:
	      header before issuing a SETUP request. (Added in 7.20.0)

       CURLOPT_RTSP_HEADER
	      This option is simply an alias for CURLOPT_HTTP_HEADER. Use  this  to  replace  the
	      standard	headers  that  RTSP and HTTP share. It is also valid to use the shortcuts
	      such as CURLOPT_USERAGENT. (Added in 7.20.0)

       CURLOPT_RTSP_CLIENT_CSEQ
	      Manually set the the CSEQ number to issue for the next RTSP request. Useful if  the
	      application  is  resuming  a  previously broken connection. The CSEQ will increment
	      from this new number henceforth. (Added in 7.20.0)

       CURLOPT_RTSP_SERVER_CSEQ
	      Manually set the CSEQ number to expect for the next  RTSP  Server->Client  request.
	      At  the  moment,	this  feature  (listening  for Server requests) is unimplemented.
	      (Added in 7.20.0)

PROTOCOL OPTIONS
       CURLOPT_TRANSFERTEXT
	      A parameter set to 1 tells the library to use ASCII mode for FTP transfers, instead
	      of  the  default	binary	transfer. For win32 systems it does not set the stdout to
	      binary mode. This option can be usable when transferring text data between  systems
	      with different views on certain characters, such as newlines or similar.

	      libcurl  does  not  do  a complete ASCII conversion when doing ASCII transfers over
	      FTP. This is a known limitation/flaw that nobody has rectified. libcurl simply sets
	      the mode to ASCII and performs a standard transfer.

       CURLOPT_PROXY_TRANSFER_MODE
	      Pass  a  long. If the value is set to 1 (one), it tells libcurl to set the transfer
	      mode (binary or ASCII) for FTP transfers	done  via  a  HTTP  proxy,  by	appending
	      ;type=a  or  ;type=i  to the URL. Without this setting, or it being set to 0 (zero,
	      the default), CURLOPT_TRANSFERTEXT has no effect when doing FTP via a proxy. Beware
	      that not all proxies support this feature.  (Added in 7.18.0)

       CURLOPT_CRLF
	      Pass a long. If the value is set to 1 (one), libcurl converts Unix newlines to CRLF
	      newlines on transfers. Disable this option again by setting the value to 0 (zero).

       CURLOPT_RANGE
	      Pass a char * as parameter, which should contain the specified range you	want.  It
	      should  be  in  the format "X-Y", where X or Y may be left out. HTTP transfers also
	      support several intervals, separated with commas as in "X-Y,N-M". Using  this  kind
	      of  multiple  intervals will cause the HTTP server to send the response document in
	      pieces (using standard MIME separation techniques). For RTSP, the formatting  of	a
	      range should follow RFC2326 Section 12.29. For RTSP, byte ranges are not permitted.
	      Instead, ranges should be given in npt, utc, or smpte formats.

	      Pass a NULL to this option to disable the use of ranges.

	      Ranges work on HTTP, FTP, FILE (since 7.18.0), and RTSP  (since  7.20.0)	transfers
	      only.

       CURLOPT_RESUME_FROM
	      Pass  a  long as parameter. It contains the offset in number of bytes that you want
	      the transfer to start from. Set this option to 0 to make the  transfer  start  from
	      the  beginning  (effectively  disabling  resume). For FTP, set this option to -1 to
	      make the transfer start from the end of the target  file	(useful  to  continue  an
	      interrupted upload).

	      When  doing uploads with FTP, the resume position is where in the local/source file
	      libcurl should try to resume the upload from and it will	then  append  the  source
	      file to the remote target file.

       CURLOPT_RESUME_FROM_LARGE
	      Pass  a curl_off_t as parameter. It contains the offset in number of bytes that you
	      want the transfer to start from. (Added in 7.11.0)

       CURLOPT_CUSTOMREQUEST
	      Pass a pointer to a zero terminated string as parameter. It can be used to  specify
	      the  request instead of GET or HEAD when performing HTTP based requests, instead of
	      LIST and NLST when performing FTP directory listings and instead of LIST	and  RETR
	      when  issuing  POP3  based  commands. This is particularly useful, for example, for
	      performing a HTTP DELETE request or a POP3 DELE command.

	      Please don't perform this at will, on HTTP based	requests,  by  making  sure  your
	      server supports the command you are sending first.

	      When  you  change the request method by setting CURLOPT_CUSTOMREQUEST to something,
	      you don't actually change how libcurl behaves or acts in regards to the  particular
	      request method, it will only change the actual string sent in the request.

	      For example:

	      With the HTTP protocol when you tell libcurl to do a HEAD request, but then specify
	      a GET though a custom request libcurl will still act as  if  it  sent  a	HEAD.  To
	      switch  to  a  proper  HEAD use CURLOPT_NOBODY, to switch to a proper POST use CUR-
	      LOPT_POST or CURLOPT_POSTFIELDS and to switch to a proper GET use CURLOPT_HTTPGET.

	      With the POP3 protocol when you tell libcurl to use a custom request it will behave
	      like  a  LIST  or RETR command was sent where it expects data to be returned by the
	      server. As such CURLOPT_NOBODY should be used when specifying commands such as DELE
	      and NOOP for example.

	      Restore to the internal default by setting this to NULL.

	      Many  people have wrongly used this option to replace the entire request with their
	      own, including multiple headers and POST contents. While that might  work  in  many
	      cases, it will cause libcurl to send invalid requests and it could possibly confuse
	      the remote server badly. Use CURLOPT_POST and CURLOPT_POSTFIELDS to set POST  data.
	      Use CURLOPT_HTTPHEADER to replace or extend the set of headers sent by libcurl. Use
	      CURLOPT_HTTP_VERSION to change HTTP version.

	      (Support for POP3 added in 7.26.0)

       CURLOPT_FILETIME
	      Pass a long. If it is 1, libcurl will attempt to get the modification date  of  the
	      remote  document	in this operation. This requires that the remote server sends the
	      time or replies to a time querying command. The curl_easy_getinfo(3) function  with
	      the CURLINFO_FILETIME argument can be used after a transfer to extract the received
	      time (if any).

       CURLOPT_NOBODY
	      A parameter set to 1 tells the library to not include the body-part in the  output.
	      This  is	only  relevant for protocols that have separate header and body parts. On
	      HTTP(S) servers, this will make libcurl do a HEAD request.

	      To change request to GET, you should use CURLOPT_HTTPGET. Change	request  to  POST
	      with CURLOPT_POST etc.

       CURLOPT_INFILESIZE
	      When  uploading a file to a remote site, this option should be used to tell libcurl
	      what the expected size of the infile is. This value should be passed as a long. See
	      also CURLOPT_INFILESIZE_LARGE.

	      For uploading using SCP, this option or CURLOPT_INFILESIZE_LARGE is mandatory.

	      When  sending  emails  using SMTP, this command can be used to specify the optional
	      SIZE parameter for the MAIL FROM command. (Added in 7.23.0)

	      This option does not limit how much data libcurl will actually  send,  as  that  is
	      controlled entirely by what the read callback returns.

       CURLOPT_INFILESIZE_LARGE
	      When  uploading a file to a remote site, this option should be used to tell libcurl
	      what the expected size of the  infile  is.   This  value	should	be  passed  as	a
	      curl_off_t. (Added in 7.11.0)

	      For uploading using SCP, this option or CURLOPT_INFILESIZE is mandatory.

	      This  option  does  not  limit how much data libcurl will actually send, as that is
	      controlled entirely by what the read callback returns.

       CURLOPT_UPLOAD
	      A parameter set to 1 tells the library to prepare for an upload. The  CURLOPT_READ-
	      DATA  and CURLOPT_INFILESIZE or CURLOPT_INFILESIZE_LARGE options are also interest-
	      ing for uploads. If the protocol is HTTP, uploading means  using	the  PUT  request
	      unless you tell libcurl otherwise.

	      Using  PUT  with	HTTP 1.1 implies the use of a "Expect: 100-continue" header.  You
	      can disable this header with CURLOPT_HTTPHEADER as usual.

	      If you use PUT to a HTTP 1.1 server, you can upload data without knowing	the  size
	      before starting the transfer if you use chunked encoding. You enable this by adding
	      a header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER. With	HTTP  1.0
	      or without chunked transfer, you must specify the size.

       CURLOPT_MAXFILESIZE
	      Pass a long as parameter. This allows you to specify the maximum size (in bytes) of
	      a file to download. If the file requested is larger than this value,  the  transfer
	      will not start and CURLE_FILESIZE_EXCEEDED will be returned.

	      The file size is not always known prior to download, and for such files this option
	      has no effect even if the file transfer ends up being larger than this given limit.
	      This concerns both FTP and HTTP transfers.

       CURLOPT_MAXFILESIZE_LARGE
	      Pass  a  curl_off_t  as  parameter. This allows you to specify the maximum size (in
	      bytes) of a file to download. If the file requested is larger than this value,  the
	      transfer	will  not  start  and CURLE_FILESIZE_EXCEEDED will be returned. (Added in
	      7.11.0)

	      The file size is not always known prior to download, and for such files this option
	      has no effect even if the file transfer ends up being larger than this given limit.
	      This concerns both FTP and HTTP transfers.

       CURLOPT_TIMECONDITION
	      Pass a long as parameter. This defines how  the  CURLOPT_TIMEVALUE  time	value  is
	      treated.	You  can  set  this  parameter	to CURL_TIMECOND_IFMODSINCE or CURL_TIME-
	      COND_IFUNMODSINCE. This feature applies to HTTP, FTP, RTSP, and FILE.

	      The last modification time of a file is not always known and in such instances this
	      feature  will  have  no effect even if the given time condition would not have been
	      met. curl_easy_getinfo(3) with the  CURLINFO_CONDITION_UNMET  option  can  be  used
	      after a transfer to learn if a zero-byte successful "transfer" was due to this con-
	      dition not matching.

       CURLOPT_TIMEVALUE
	      Pass a long as parameter. This should be the time in seconds since 1 Jan 1970,  and
	      the time will be used in a condition as specified with CURLOPT_TIMECONDITION.

CONNECTION OPTIONS
       CURLOPT_TIMEOUT
	      Pass  a long as parameter containing the maximum time in seconds that you allow the
	      libcurl transfer operation to take. Normally, name lookups can take a  considerable
	      time  and  limiting  operations  to less than a few minutes risk aborting perfectly
	      normal operations. This option will cause curl to use the SIGALRM to  enable  time-
	      outing system calls.

	      In  unix-like  systems, this might cause signals to be used unless CURLOPT_NOSIGNAL
	      is set.

	      Default timeout is 0 (zero) which means it never times out.

       CURLOPT_TIMEOUT_MS
	      Like CURLOPT_TIMEOUT but takes number of milliseconds instead. If libcurl is  built
	      to  use  the standard system name resolver, that portion of the transfer will still
	      use full-second resolution for timeouts with a minimum timeout allowed of one  sec-
	      ond.  (Added in 7.16.2)

       CURLOPT_LOW_SPEED_LIMIT
	      Pass  a  long as parameter. It contains the transfer speed in bytes per second that
	      the transfer should be below during CURLOPT_LOW_SPEED_TIME seconds for the  library
	      to consider it too slow and abort.

       CURLOPT_LOW_SPEED_TIME
	      Pass  a long as parameter. It contains the time in seconds that the transfer should
	      be below the CURLOPT_LOW_SPEED_LIMIT for the library to consider it  too	slow  and
	      abort.

       CURLOPT_MAX_SEND_SPEED_LARGE
	      Pass  a curl_off_t as parameter.	If an upload exceeds this speed (counted in bytes
	      per second) on cumulative average during the transfer, the transfer will	pause  to
	      keep  the  average  rate	less  than  or equal to the parameter value.  Defaults to
	      unlimited speed. (Added in 7.15.5)

       CURLOPT_MAX_RECV_SPEED_LARGE
	      Pass a curl_off_t as parameter.  If a download exceeds this speed (counted in bytes
	      per  second)  on cumulative average during the transfer, the transfer will pause to
	      keep the average rate less than or equal to the parameter value. Defaults to unlim-
	      ited speed. (Added in 7.15.5)

       CURLOPT_MAXCONNECTS
	      Pass  a  long. The set number will be the persistent connection cache size. The set
	      amount will be the maximum amount of simultaneously open connections  that  libcurl
	      may cache in this easy handle. Default is 5, and there isn't much point in changing
	      this value unless you are perfectly aware of how this works and  changes	libcurl's
	      behaviour.  This	concerns connections using any of the protocols that support per-
	      sistent connections.

	      When reaching the maximum limit, curl closes the oldest one in the cache to prevent
	      increasing the number of open connections.

	      If  you  already	have performed transfers with this curl handle, setting a smaller
	      MAXCONNECTS than before may cause open connections to get closed unnecessarily.

	      If you add this easy handle to a multi handle, this setting  is  not  acknowledged,
	      and you must instead use curl_multi_setopt(3) and the CURLMOPT_MAXCONNECTS option.

       CURLOPT_CLOSEPOLICY
	      (Obsolete) This option does nothing.

       CURLOPT_FRESH_CONNECT
	      Pass  a  long.  Set  to 1 to make the next transfer use a new (fresh) connection by
	      force. If the connection cache is full before this connection, one of the  existing
	      connections  will  be  closed  as according to the selected or default policy. This
	      option should be used with caution and only if you understand  what  it  does.  Set
	      this  to	0 to have libcurl attempt re-using an existing connection (default behav-
	      ior).

       CURLOPT_FORBID_REUSE
	      Pass a long. Set to 1 to make the next transfer  explicitly  close  the  connection
	      when  done. Normally, libcurl keeps all connections alive when done with one trans-
	      fer in case a succeeding one follows that can re-use them.  This option  should  be
	      used with caution and only if you understand what it does. Set to 0 to have libcurl
	      keep the connection open for possible later re-use (default behavior).

       CURLOPT_CONNECTTIMEOUT
	      Pass a long. It should contain the maximum time in seconds that you allow the  con-
	      nection  to the server to take.  This only limits the connection phase, once it has
	      connected, this option is of no more use. Set to zero  to  switch  to  the  default
	      built-in connection timeout - 300 seconds. See also the CURLOPT_TIMEOUT option.

	      In  unix-like  systems, this might cause signals to be used unless CURLOPT_NOSIGNAL
	      is set.

       CURLOPT_CONNECTTIMEOUT_MS
	      Like CURLOPT_CONNECTTIMEOUT but  takes  the  number  of  milliseconds  instead.  If
	      libcurl is built to use the standard system name resolver, that portion of the con-
	      nect will still use full-second resolution for  timeouts	with  a  minimum  timeout
	      allowed of one second.  (Added in 7.16.2)

       CURLOPT_IPRESOLVE
	      Allows  an  application  to  select what kind of IP addresses to use when resolving
	      host names. This is only interesting when using host names that  resolve	addresses
	      using more than one version of IP. The allowed values are:

	      CURL_IPRESOLVE_WHATEVER
		     Default, resolves addresses to all IP versions that your system allows.

	      CURL_IPRESOLVE_V4
		     Resolve to IPv4 addresses.

	      CURL_IPRESOLVE_V6
		     Resolve to IPv6 addresses.

       CURLOPT_CONNECT_ONLY
	      Pass  a  long.  If  the parameter equals 1, it tells the library to perform all the
	      required proxy authentication and connection setup, but  no  data  transfer.   This
	      option is implemented for HTTP, SMTP and POP3.

	      The  option can be used to simply test a connection to a server, but is more useful
	      when used with  the  CURLINFO_LASTSOCKET	option	to  curl_easy_getinfo(3)  as  the
	      library  can  set  up  the  connection and then the application can obtain the most
	      recently used socket for special data transfers. (Added in 7.15.2)

       CURLOPT_USE_SSL
	      Pass a long using one of the values from below, to make libcurl  use  your  desired
	      level of SSL for the transfer. (Added in 7.11.0)

	      This is for enabling SSL/TLS when you use FTP, SMTP, POP3, IMAP etc.

	      (This  option  was  known  as  CURLOPT_FTP_SSL up to 7.16.4, and the constants were
	      known as CURLFTPSSL_*)

	      CURLUSESSL_NONE
		     Don't attempt to use SSL.

	      CURLUSESSL_TRY
		     Try using SSL, proceed as normal otherwise.

	      CURLUSESSL_CONTROL
		     Require SSL for the control connection or fail with CURLE_USE_SSL_FAILED.

	      CURLUSESSL_ALL
		     Require SSL for all communication or fail with CURLE_USE_SSL_FAILED.

       CURLOPT_RESOLVE
	      Pass a pointer to a linked list of strings with host name  resolve  information  to
	      use  for requests with this handle. The linked list should be a fully valid list of
	      struct curl_slist structs properly filled in. Use  curl_slist_append(3)  to  create
	      the list and curl_slist_free_all(3) to clean up an entire list.

	      Each   single   name   resolve   string	should	 be   written  using  the  format
	      HOST:PORT:ADDRESS where HOST is the name libcurl will try to resolve, PORT  is  the
	      port  number  of the service where libcurl wants to connect to the HOST and ADDRESS
	      is the numerical IP address. If libcurl is built to support IPv6,  ADDRESS  can  of
	      course be either IPv4 or IPv6 style addressing.

	      This  option effectively pre-populates the DNS cache with entries for the host+port
	      pair so redirects and everything that operations against the HOST+PORT will instead
	      use your provided ADDRESS.

	      You  can	remove	names  from  the  DNS  cache  again, to stop providing these fake
	      resolves,  by  including	a  string  in  the  linked  list  that	uses  the  format
	      "-HOST:PORT".  The  host	name  must be prefixed with a dash, and the host name and
	      port number must exactly match what was already added previously.

	      (Added in 7.21.3)

       CURLOPT_DNS_SERVERS
	      Set the list of DNS servers to be used instead of the system default.   The  format
	      of the dns servers option is:

	      host[:port][,host[:port]]...

	      For example:

	      192.168.1.100,192.168.1.101,3.4.5.6

	      This  option  requires that libcurl was built with a resolver backend that supports
	      this operation. The c-ares backend is the only such one.

	      (Added in 7.24.0)

       CURLOPT_ACCEPTTIMEOUT_MS
	      Pass a long telling libcurl the maximum number of milliseconds to wait for a server
	      to  connect back to libcurl when an active FTP connection is used. If no timeout is
	      set, the internal default of 60000 will be used. (Added in 7.24.0)

SSL and SECURITY OPTIONS
       CURLOPT_SSLCERT
	      Pass a pointer to a zero terminated string as parameter. The string should  be  the
	      file  name of your certificate. The default format is "PEM" and can be changed with
	      CURLOPT_SSLCERTTYPE.

	      With NSS this can also be the nickname of the certificate you wish to  authenticate
	      with.  If you want to use a file from the current directory, please precede it with
	      "./" prefix, in order to avoid confusion with a nickname.

       CURLOPT_SSLCERTTYPE
	      Pass a pointer to a zero terminated string as parameter. The string should  be  the
	      format  of  your	certificate.  Supported  formats  are "PEM" and "DER".	(Added in
	      7.9.3)

       CURLOPT_SSLKEY
	      Pass a pointer to a zero terminated string as parameter. The string should  be  the
	      file  name of your private key. The default format is "PEM" and can be changed with
	      CURLOPT_SSLKEYTYPE.

       CURLOPT_SSLKEYTYPE
	      Pass a pointer to a zero terminated string as parameter. The string should  be  the
	      format of your private key. Supported formats are "PEM", "DER" and "ENG".

	      The  format "ENG" enables you to load the private key from a crypto engine. In this
	      case CURLOPT_SSLKEY is used as an identifier passed to the engine. You have to  set
	      the crypto engine with CURLOPT_SSLENGINE.  "DER" format key file currently does not
	      work because of a bug in OpenSSL.

       CURLOPT_KEYPASSWD
	      Pass a pointer to a zero terminated string as parameter. It will	be  used  as  the
	      password	required to use the CURLOPT_SSLKEY or CURLOPT_SSH_PRIVATE_KEYFILE private
	      key.  You never needed a pass phrase to load a certificate but you need one to load
	      your private key.

	      (This  option  was  known as CURLOPT_SSLKEYPASSWD up to 7.16.4 and CURLOPT_SSLCERT-
	      PASSWD up to 7.9.2)

       CURLOPT_SSLENGINE
	      Pass a pointer to a zero terminated string as parameter. It will	be  used  as  the
	      identifier for the crypto engine you want to use for your private key.

	      If the crypto device cannot be loaded, CURLE_SSL_ENGINE_NOTFOUND is returned.

       CURLOPT_SSLENGINE_DEFAULT
	      Sets the actual crypto engine as the default for (asymmetric) crypto operations.

	      If the crypto device cannot be set, CURLE_SSL_ENGINE_SETFAILED is returned.

	      Even  though  this  option  doesn't  need  any  parameter,  in  some configurations
	      curl_easy_setopt might be defined as a macro taking exactly three arguments. There-
	      fore, it's recommended to pass 1 as parameter to this option.

       CURLOPT_SSLVERSION
	      Pass  a  long  as  parameter  to control what version of SSL/TLS to attempt to use.
	      (Added in 7.9.2)

	      The available options are:

	      CURL_SSLVERSION_DEFAULT
		     The default action. This will attempt to figure out the remote SSL  protocol
		     version, i.e. either SSLv3 or TLSv1 (but not SSLv2, which became disabled by
		     default with 7.18.1).

	      CURL_SSLVERSION_TLSv1
		     Force TLSv1.x

	      CURL_SSLVERSION_SSLv2
		     Force SSLv2

	      CURL_SSLVERSION_SSLv3
		     Force SSLv3

	      CURL_SSLVERSION_TLSv1_0
		     Force TLSv1.0 (Added in 7.34.0)

	      CURL_SSLVERSION_TLSv1_1
		     Force TLSv1.1 (Added in 7.34.0)

	      CURL_SSLVERSION_TLSv1_2
		     Force TLSv1.2 (Added in 7.34.0)

       CURLOPT_SSL_VERIFYPEER
	      Pass a long as parameter. By default, curl assumes a value of 1.

	      This option determines whether curl verifies the authenticity of	the  peer's  cer-
	      tificate. A value of 1 means curl verifies; 0 (zero) means it doesn't.

	      When  negotiating  a  SSL connection, the server sends a certificate indicating its
	      identity.  Curl verifies whether the certificate is authentic, i.e.  that  you  can
	      trust  that the server is who the certificate says it is.  This trust is based on a
	      chain of digital signatures, rooted in certification  authority  (CA)  certificates
	      you  supply.   curl  uses a default bundle of CA certificates (the path for that is
	      determined at build time) and you can specify alternate certificates with the  CUR-
	      LOPT_CAINFO option or the CURLOPT_CAPATH option.

	      When  CURLOPT_SSL_VERIFYPEER  is	nonzero, and the verification fails to prove that
	      the certificate is authentic, the connection fails.  When the option is  zero,  the
	      peer certificate verification succeeds regardless.

	      Authenticating the certificate is not by itself very useful.  You typically want to
	      ensure that the server, as authentically identified  by  its  certificate,  is  the
	      server  you mean to be talking to.  Use CURLOPT_SSL_VERIFYHOST to control that. The
	      check that the host name in the certificate is valid for the host name you're  con-
	      necting to is done independently of the CURLOPT_SSL_VERIFYPEER option.

       CURLOPT_CAINFO
	      Pass  a  char  * to a zero terminated string naming a file holding one or more cer-
	      tificates to verify the peer with.  This makes sense only when used in  combination
	      with  the  CURLOPT_SSL_VERIFYPEER  option.  If CURLOPT_SSL_VERIFYPEER is zero, CUR-
	      LOPT_CAINFO need not even indicate an accessible file.

	      This option is by default set to the system path where libcurl's cacert  bundle  is
	      assumed to be stored, as established at build time.

	      If  curl	is  built  against  the NSS SSL library, the NSS PEM PKCS#11 module (lib-
	      nsspem.so) needs to be available for this option to work properly.

       CURLOPT_ISSUERCERT
	      Pass a char * to a zero terminated string naming a file holding a CA certificate in
	      PEM  format. If the option is set, an additional check against the peer certificate
	      is performed to verify the issuer is indeed the one associated with the certificate
	      provided	by  the  option. This additional check is useful in multi-level PKI where
	      one needs to enforce that the peer certificate is from a	specific  branch  of  the
	      tree.

	      This  option  makes  sense only when used in combination with the CURLOPT_SSL_VERI-
	      FYPEER option. Otherwise, the result of the check is not considered as failure.

	      A specific error code (CURLE_SSL_ISSUER_ERROR) is defined with the option, which is
	      returned	if the setup of the SSL/TLS session has failed due to a mismatch with the
	      issuer of peer certificate (CURLOPT_SSL_VERIFYPEER has to be set too for the  check
	      to fail). (Added in 7.19.0)

       CURLOPT_CAPATH
	      Pass  a  char  * to a zero terminated string naming a directory holding multiple CA
	      certificates to verify the peer with. If libcurl is built against OpenSSL, the cer-
	      tificate directory must be prepared using the openssl c_rehash utility.  This makes
	      sense only when used in combination with	the  CURLOPT_SSL_VERIFYPEER  option.   If
	      CURLOPT_SSL_VERIFYPEER is zero, CURLOPT_CAPATH need not even indicate an accessible
	      path.  The CURLOPT_CAPATH function apparently does not work in Windows due to  some
	      limitation  in openssl. This option is OpenSSL-specific and does nothing if libcurl
	      is built to use GnuTLS. NSS-powered libcurl provides the option only  for  backward
	      compatibility.

       CURLOPT_CRLFILE
	      Pass  a  char * to a zero terminated string naming a file with the concatenation of
	      CRL (in PEM format) to use in the certificate validation that occurs during the SSL
	      exchange.

	      When  curl  is  built to use NSS or GnuTLS, there is no way to influence the use of
	      CRL passed to help in the verification process. When libcurl is built with  OpenSSL
	      support,	X509_V_FLAG_CRL_CHECK and X509_V_FLAG_CRL_CHECK_ALL are both set, requir-
	      ing CRL check against all the elements of the certificate chain if a  CRL  file  is
	      passed.

	      This  option  makes  sense only when used in combination with the CURLOPT_SSL_VERI-
	      FYPEER option.

	      A specific error code (CURLE_SSL_CRL_BADFILE) is defined with  the  option.  It  is
	      returned	when  the  SSL	exchange  fails because the CRL file cannot be loaded.	A
	      failure in certificate verification due to a revocation information  found  in  the
	      CRL does not trigger this specific error. (Added in 7.19.0)

       CURLOPT_SSL_VERIFYHOST
	      Pass a long as parameter.

	      This  option  determines	whether  libcurl verifies that the server cert is for the
	      server it is known as.

	      When negotiating a SSL connection, the server sends a  certificate  indicating  its
	      identity.

	      When CURLOPT_SSL_VERIFYHOST is 2, that certificate must indicate that the server is
	      the server to which you meant to connect, or the connection fails.

	      Curl considers the server the intended one when the Common Name field or a  Subject
	      Alternate  Name  field in the certificate matches the host name in the URL to which
	      you told Curl to connect.

	      When the value is 1, libcurl will return a failure. It was  previously  (in  7.28.0
	      and  earlier)  a	debug  option of some sorts, but it is no longer supported due to
	      frequently leading to programmer mistakes.

	      When the value is 0, the connection succeeds regardless of the names  in	the  cer-
	      tificate.

	      The default value for this option is 2.

	      This  option  controls  checking	the server's certificate's claimed identity.  The
	      server could be lying.  To control lying, see CURLOPT_SSL_VERIFYPEER.   If  libcurl
	      is  built against NSS and CURLOPT_SSL_VERIFYPEER is zero, CURLOPT_SSL_VERIFYHOST is
	      ignored.

       CURLOPT_CERTINFO
	      Pass a long set to 1 to enable libcurl's certificate chain info gatherer. With this
	      enabled,	libcurl (if built with OpenSSL) will extract lots of information and data
	      about the certificates in the certificate chain used in the  SSL	connection.  This
	      data  is	then  possible to extract after a transfer using curl_easy_getinfo(3) and
	      its option CURLINFO_CERTINFO. (Added in 7.19.1)

       CURLOPT_RANDOM_FILE
	      Pass a char * to a zero terminated file name. The file will be used to read from to
	      seed  the  random  engine  for SSL. The more random the specified file is, the more
	      secure the SSL connection will become.

       CURLOPT_EGDSOCKET
	      Pass a char * to the zero terminated path name  to  the  Entropy	Gathering  Daemon
	      socket. It will be used to seed the random engine for SSL.

       CURLOPT_SSL_CIPHER_LIST
	      Pass  a char *, pointing to a zero terminated string holding the list of ciphers to
	      use for the SSL connection. The list must be syntactically correct, it consists  of
	      one  or  more cipher strings separated by colons. Commas or spaces are also accept-
	      able separators but colons are normally used, !, - and + can be used as operators.

	      For  OpenSSL  and  GnuTLS  valid	examples  of  cipher  lists  include   'RC4-SHA',
	      'SHA1+DES',  'TLSv1'  and 'DEFAULT'. The default list is normally set when you com-
	      pile OpenSSL.

	      You'll	find	more	details    about    cipher    lists    on    this    URL:
	      http://www.openssl.org/docs/apps/ciphers.html

	      For    NSS,   valid   examples   of   cipher   lists   include   'rsa_rc4_128_md5',
	      'rsa_aes_128_sha', etc. With NSS you don't add/remove ciphers.  If  one  uses  this
	      option then all known ciphers are disabled and only those passed in are enabled.

	      You'll find more details about the NSS cipher lists on this URL: http://git.fedora-
	      hosted.org/cgit/mod_nss.git/plain/docs/mod_nss.html#Directives

       CURLOPT_SSL_SESSIONID_CACHE
	      Pass a long set to 0 to disable libcurl's use of SSL session-ID caching.	Set  this
	      to 1 to enable it. By default all transfers are done using the cache. While nothing
	      ever should get hurt by attempting to reuse SSL session-IDs, there seem to be  bro-
	      ken  SSL	implementations in the wild that may require you to disable this in order
	      for you to succeed. (Added in 7.16.0)

       CURLOPT_SSL_OPTIONS
	      Pass a long with a bitmask to tell libcurl about specific SSL behaviors.

	      CURLSSLOPT_ALLOW_BEAST is the only supported bit and by setting this the user  will
	      tell  libcurl to not attempt to use any workarounds for a security flaw in the SSL3
	      and TLS1.0 protocols.  If this option isn't used or this bit is set to 0,  the  SSL
	      layer  libcurl  uses  may  use  a work-around for this flaw although it might cause
	      interoperability problems with some (older) SSL implementations. WARNING:  avoiding
	      this  work-around loosens the security, and by setting this option to 1 you ask for
	      exactly that. (Added in 7.25.0)

       CURLOPT_KRBLEVEL
	      Pass a char * as parameter. Set the kerberos security  level  for  FTP;  this  also
	      enables  kerberos  awareness.  This is a string, 'clear', 'safe', 'confidential' or
	      'private'.  If the string is set but doesn't match one of these, 'private' will  be
	      used. Set the string to NULL to disable kerberos support for FTP.

	      (This option was known as CURLOPT_KRB4LEVEL up to 7.16.3)

       CURLOPT_GSSAPI_DELEGATION
	      Set  the parameter to CURLGSSAPI_DELEGATION_FLAG to allow unconditional GSSAPI cre-
	      dential delegation.  The delegation is disabled by default since 7.21.7.	 Set  the
	      parameter  to CURLGSSAPI_DELEGATION_POLICY_FLAG to delegate only if the OK-AS-DELE-
	      GATE flag is set in the service ticket in case this feature  is  supported  by  the
	      GSSAPI  implementation  and the definition of GSS_C_DELEG_POLICY_FLAG was available
	      at compile-time.	(Added in 7.22.0)

SSH OPTIONS
       CURLOPT_SSH_AUTH_TYPES
	      Pass a long set to a bitmask consisting of one or more  of  CURLSSH_AUTH_PUBLICKEY,
	      CURLSSH_AUTH_PASSWORD,	   CURLSSH_AUTH_HOST,	   CURLSSH_AUTH_KEYBOARD      and
	      CURLSSH_AUTH_AGENT. Set CURLSSH_AUTH_ANY to let libcurl pick a suitable  one.  Cur-
	      rently  CURLSSH_AUTH_HOST has no effect. (Added in 7.16.1) If CURLSSH_AUTH_AGENT is
	      used, libcurl attempts to connect to ssh-agent or pageant and let the agent attempt
	      the authentication. (Added in 7.28.0)

       CURLOPT_SSH_HOST_PUBLIC_KEY_MD5
	      Pass  a  char  *	pointing to a string containing 32 hexadecimal digits. The string
	      should be the 128 bit MD5 checksum of the remote host's  public  key,  and  libcurl
	      will  reject  the  connection  to the host unless the md5sums match. This option is
	      only for SCP and SFTP transfers. (Added in 7.17.1)

       CURLOPT_SSH_PUBLIC_KEYFILE
	      Pass a char * pointing to a file name for your public key.  If  not  used,  libcurl
	      defaults to $HOME/.ssh/id_dsa.pub if the HOME environment variable is set, and just
	      "id_dsa.pub" in the current directory if HOME is not set.  (Added in 7.16.1) If  an
	      empty string is passed, libcurl will pass no public key to libssh2 which then tries
	      to compute it from the private key, this is known to work when  libssh2  1.4.0+  is
	      linked against OpenSSL. (Added in 7.26.0)

       CURLOPT_SSH_PRIVATE_KEYFILE
	      Pass  a  char  * pointing to a file name for your private key. If not used, libcurl
	      defaults to $HOME/.ssh/id_dsa if the HOME environment variable  is  set,	and  just
	      "id_dsa" in the current directory if HOME is not set.  If the file is password-pro-
	      tected, set the password with CURLOPT_KEYPASSWD. (Added in 7.16.1)

       CURLOPT_SSH_KNOWNHOSTS
	      Pass a pointer to a zero terminated string holding the file name of the  known_host
	      file  to use.  The known_hosts file should use the OpenSSH file format as supported
	      by libssh2. If this file is specified, libcurl will only	accept	connections  with
	      hosts that are known and present in that file, with a matching public key. Use CUR-
	      LOPT_SSH_KEYFUNCTION to alter the default behavior on host and  key  (mis)matching.
	      (Added in 7.19.6)

       CURLOPT_SSH_KEYFUNCTION
	      Pass  a  pointer	to  a  curl_sshkeycallback  function.  It  gets  called  when the
	      known_host matching has been done, to allow the application to act and  decide  for
	      libcurl  how to proceed. The callback will only be called if CURLOPT_SSH_KNOWNHOSTS
	      is also set.

	      The curl_sshkeycallback function gets passed the CURL  handle,  the  key	from  the
	      known_hosts  file,  the key from the remote site, info from libcurl on the matching
	      status and a custom pointer (set with CURLOPT_SSH_KEYDATA). It MUST return  one  of
	      the following return codes to tell libcurl how to act:

	      CURLKHSTAT_FINE_ADD_TO_FILE
		     The  host+key is accepted and libcurl will append it to the known_hosts file
		     before continuing with the connection. This will also add the host+key combo
		     to  the  known_host  pool kept in memory if it wasn't already present there.
		     The adding of data to the file is done by completely replacing the file with
		     a new copy, so the permissions of the file must allow this.

	      CURLKHSTAT_FINE
		     The  host+key  is	accepted  libcurl will continue with the connection. This
		     will also add the host+key combo to the known_host pool kept in memory if it
		     wasn't already present there.

	      CURLKHSTAT_REJECT
		     The  host+key  is rejected. libcurl will deny the connection to continue and
		     it will be closed.

	      CURLKHSTAT_DEFER
		     The host+key is rejected, but the SSH connection is asked to be kept  alive.
		     This feature could be used when the app wants to somehow return back and act
		     on the host+key situation and then retry without  needing	the  overhead  of
		     setting it up from scratch again.
	(Added in 7.19.6)

       CURLOPT_SSH_KEYDATA
	      Pass a void * as parameter. This pointer will be passed along verbatim to the call-
	      back set with CURLOPT_SSH_KEYFUNCTION. (Added in 7.19.6)

OTHER OPTIONS
       CURLOPT_PRIVATE
	      Pass a void * as parameter, pointing to data that should be  associated  with  this
	      curl  handle.  The pointer can subsequently be retrieved using curl_easy_getinfo(3)
	      with the CURLINFO_PRIVATE option. libcurl  itself  does  nothing	with  this  data.
	      (Added in 7.10.3)

       CURLOPT_SHARE
	      Pass  a  share  handle as a parameter. The share handle must have been created by a
	      previous call to curl_share_init(3). Setting this option, will make this curl  han-
	      dle use the data from the shared handle instead of keeping the data to itself. This
	      enables several curl handles to share data. If the curl handles are used simultane-
	      ously  in  multiple  threads, you MUST use the locking methods in the share handle.
	      See curl_share_setopt(3) for details.

	      If you add a share that is set to share cookies, your easy  handle  will	use  that
	      cookie  cache  and get the cookie engine enabled. If you unshare an object that was
	      using cookies (or change to another object that doesn't share  cookies),	the  easy
	      handle will get its cookie engine disabled.

	      Data that the share object is not set to share will be dealt with the usual way, as
	      if no share was used.

       CURLOPT_NEW_FILE_PERMS
	      Pass a long as a parameter, containing the value of the permissions  that  will  be
	      assigned	to  newly created files on the remote server.  The default value is 0644,
	      but any valid value can be used.	The only protocols that can use this are sftp://,
	      scp://, and file://. (Added in 7.16.4)

       CURLOPT_NEW_DIRECTORY_PERMS
	      Pass  a  long  as a parameter, containing the value of the permissions that will be
	      assigned to newly created directories on the remote server.  The default	value  is
	      0755,  but  any  valid value can be used.  The only protocols that can use this are
	      sftp://, scp://, and file://.  (Added in 7.16.4)

TELNET OPTIONS
       CURLOPT_TELNETOPTIONS
	      Provide a pointer to a curl_slist with variables to pass	to  the  telnet  negotia-
	      tions.  The  variables should be in the format <option=value>. libcurl supports the
	      options 'TTYPE', 'XDISPLOC' and 'NEW_ENV'. See the TELNET standard for details.

RETURN VALUE
       CURLE_OK (zero) means that the option was set properly, non-zero means an  error  occurred
       as  <curl/curl.h>  defines.  See  the  libcurl-errors(3)  man  page for the full list with
       descriptions.

       If you try to set an option that libcurl doesn't know about, perhaps because  the  library
       is too old to support it or the option was removed in a recent version, this function will
       return CURLE_FAILED_INIT.

SEE ALSO
       curl_easy_init(3), curl_easy_cleanup(3), curl_easy_reset(3)

libcurl 7.20.0				    1 Jan 2010			      curl_easy_setopt(3)


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