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+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" *
+.\" * This software is licensed as described in the file COPYING, which
+.\" * you should have received as part of this distribution. The terms
+.\" * are also available at http://curl.haxx.se/docs/copyright.html.
+.\" *
+.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+.\" * copies of the Software, and permit persons to whom the Software is
+.\" * furnished to do so, under the terms of the COPYING file.
+.\" *
+.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+.\" * KIND, either express or implied.
+.\" *
+.\" **************************************************************************
+.\"
+.TH curl_easy_setopt 3 "1 Jan 2010" "libcurl 7.20.0" "libcurl Manual"
+.SH NAME
+curl_easy_setopt \- set options for a curl easy handle
+.SH SYNOPSIS
+#include <curl/curl.h>
+
+CURLcode curl_easy_setopt(CURL *handle, CURLoption option, parameter);
+.SH DESCRIPTION
+curl_easy_setopt() is used to tell libcurl how to behave. By using the
+appropriate options to \fIcurl_easy_setopt\fP, you can change libcurl's
+behavior.  All options are set with the \fIoption\fP followed by a
+\fIparameter\fP. That parameter can be a \fBlong\fP, a \fBfunction pointer\fP,
+an \fBobject pointer\fP or a \fBcurl_off_t\fP, 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 \fIhandle\fP.  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 \fIcurl_easy_reset(3)\fP.
+
+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 \fIhandle\fP is the return code from a \fIcurl_easy_init(3)\fP or
+\fIcurl_easy_duphandle(3)\fP call.
+.SH BEHAVIOR OPTIONS
+.IP 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 understanding. The verbose information will be sent to stderr,
+or the stream set with \fICURLOPT_STDERR\fP.
+
+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
+\fICURLOPT_DEBUGFUNCTION\fP.
+.IP 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).
+.IP CURLOPT_NOPROGRESS
+Pass a long. If set to 1, it tells the library to shut off the progress meter
+completely. It will also prevent the \fICURLOPT_PROGRESSFUNCTION\fP from
+getting called.
+
+Future versions of libcurl are likely to not have any built-in progress meter
+at all.
+.IP 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 timeout 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 \fICURLOPT_NOSIGNAL\fP 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
+\fICURLAUTH_NTLM_WB\fP authentication could cause a SIGCHLD signal to be
+raised.
+.IP 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
+\fICURLOPT_URL\fP 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 \fICURLOPT_FNMATCH_FUNCTION\fP
+option.
+
+This feature is only supported by the FTP download for now.
+
+A brief introduction of its syntax follows:
+.RS
+.IP "* - ASTERISK"
+\&ftp://example.com/some/path/\fB*.txt\fP (for all txt's from the root
+directory)
+.RE
+.RS
+.IP "? - QUESTION MARK"
+Question mark matches any (exactly one) character.
+
+\&ftp://example.com/some/path/\fBphoto?.jpeg\fP
+.RE
+.RS
+.IP "[ - 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:
+
+\fB[a-zA-Z0\-9]\fP or \fB[f\-gF\-G]\fP \- character interval
+
+\fB[abc]\fP - character enumeration
+
+\fB[^abc]\fP or \fB[!abc]\fP - negation
+
+\fB[[:\fP\fIname\fP\fB:]]\fP class expression. Supported classes are
+\fBalnum\fP,\fBlower\fP, \fBspace\fP, \fBalpha\fP, \fBdigit\fP, \fBprint\fP,
+\fBupper\fP, \fBblank\fP, \fBgraph\fP, \fBxdigit\fP.
+
+\fB[][-!^]\fP - special case \- matches only '\-', ']', '[', '!' or '^'. These
+characters have no special purpose.
+
+\fB[\\[\\]\\\\]\fP - escape syntax. Matches '[', ']' or '\\'.
+
+Using the rules above, a file name pattern can be constructed:
+
+\&ftp://example.com/some/path/\fB[a-z[:upper:]\\\\].jpeg\fP
+.RE
+.PP
+(This was added in 7.21.0)
+.SH CALLBACK OPTIONS
+.IP CURLOPT_WRITEFUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBsize_t function( char *ptr, size_t size, size_t nmemb, void *userdata);\fP
+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 \fIptr\fP is \fIsize\fP
+multiplied with \fInmemb\fP, it will not be zero terminated. 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 \fICURLE_WRITE_ERROR\fP.
+
+From 7.18.0, the function can return CURL_WRITEFUNC_PAUSE which then will
+cause writing to this connection to become paused. See
+\fIcurl_easy_pause(3)\fP 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
+\fICURLOPT_WRITEDATA\fP.
+
+Set the \fIuserdata\fP argument with the \fICURLOPT_WRITEDATA\fP 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 \fICURLOPT_HEADER\fP set, which sends
+header data to the write callback, you can get up to
+\fICURL_MAX_HTTP_HEADER\fP bytes of header data passed into it. This usually
+means 100K.
+.IP CURLOPT_WRITEDATA
+Data pointer to pass to the file write function. If you use the
+\fICURLOPT_WRITEFUNCTION\fP 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 \fICURLOPT_WRITEFUNCTION\fP 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 \fBMUST\fP use the
+\fICURLOPT_WRITEFUNCTION\fP if you set this option or you will experience
+crashes.
+
+This option is also known with the older name \fICURLOPT_FILE\fP, the name
+\fICURLOPT_WRITEDATA\fP was introduced in 7.9.7.
+.IP CURLOPT_READFUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBsize_t function( void *ptr, size_t size, size_t nmemb, void *userdata);\fP
+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 \fIptr\fP may
+be filled with at most \fIsize\fP multiplied with \fInmemb\fP 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 \fICURL_READFUNC_ABORT\fP to stop the current
+operation immediately, resulting in a \fICURLE_ABORTED_BY_CALLBACK\fP 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 \fIcurl_easy_pause(3)\fP
+for further details.
+
+\fBBugs\fP: 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 \fICURLOPT_READDATA\fP.
+.IP CURLOPT_READDATA
+Data pointer to pass to the file read function. If you use the
+\fICURLOPT_READFUNCTION\fP option, this is the pointer you'll get as input. If
+you don't specify a read callback 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
+\fICURLOPT_READFUNCTION\fP if you set this option.
+
+This option was also known by the older name \fICURLOPT_INFILE\fP, the name
+\fICURLOPT_READDATA\fP was introduced in 7.9.7.
+.IP CURLOPT_IOCTLFUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBcurlioerr function(CURL *handle, int cmd, void *clientp);\fP. 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 \fICURLOPT_SEEKFUNCTION\fP instead to provide seeking!
+.IP CURLOPT_IOCTLDATA
+Pass a pointer that will be untouched by libcurl and passed as the 3rd
+argument in the ioctl callback set with \fICURLOPT_IOCTLFUNCTION\fP.  (Option
+added in 7.12.3)
+.IP CURLOPT_SEEKFUNCTION
+Pass a pointer to a function that matches the following prototype: \fBint
+function(void *instream, curl_off_t offset, int origin);\fP 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 \fIoffset\fP is not the same as defined for curl_off_t on
+many systems! (Option added in 7.18.0)
+.IP CURLOPT_SEEKDATA
+Data pointer to pass to the file seek function. If you use the
+\fICURLOPT_SEEKFUNCTION\fP option, this is the pointer you'll get as input. If
+you don't specify a seek callback, NULL is passed. (Option added in 7.18.0)
+.IP CURLOPT_SOCKOPTFUNCTION
+Pass a pointer to a function that matches the following prototype: \fBint
+function(void *clientp, curl_socket_t curlfd, curlsocktype purpose);\fP. This
+function gets called by libcurl after the socket() call but before the
+connect() call. The callback's \fIpurpose\fP argument identifies the exact
+purpose for this particular socket:
+
+\fICURLSOCKTYPE_IPCXN\fP for actively created connections or since 7.28.0
+\fICURLSOCKTYPE_ACCEPT\fP for FTP when the connection was setup with PORT/EPSV
+(in earlier versions 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 discretion.  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 \fICURLE_COULDNT_CONNECT\fP.  (Option
+added in 7.16.0)
+
+Added in 7.21.5, the callback function may return
+\fICURL_SOCKOPT_ALREADY_CONNECTED\fP, which tells libcurl that the socket is
+in fact already connected and then libcurl will not attempt to connect it.
+.IP CURLOPT_SOCKOPTDATA
+Pass a pointer that will be untouched by libcurl and passed as the first
+argument in the sockopt callback set with \fICURLOPT_SOCKOPTFUNCTION\fP.
+(Option added in 7.16.0)
+.IP CURLOPT_OPENSOCKETFUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBcurl_socket_t function(void *clientp, curlsocktype purpose, struct
+curl_sockaddr *address);\fP. This function gets called by libcurl instead of
+the \fIsocket(2)\fP call. The callback's \fIpurpose\fP argument identifies the
+exact purpose for this particular socket: \fICURLSOCKTYPE_IPCXN\fP is for IP
+based connections. Future versions of libcurl may support more purposes. It
+passes the resolved peer address as a \fIaddress\fP argument so the callback
+can modify the address or refuse to connect at all. The callback function
+should return the socket or \fICURL_SOCKET_BAD\fP in case no connection could
+be established or another error was detected. Any additional
+\fIsetsockopt(2)\fP calls can be done on the socket at the user's discretion.
+\fICURL_SOCKET_BAD\fP return value from the callback function will signal an
+unrecoverable error to the library and it will return
+\fICURLE_COULDNT_CONNECT\fP.  This return code can be used for IP address
+blacklisting.  The default behavior is:
+.nf
+   return socket(addr->family, addr->socktype, addr->protocol);
+.fi
+(Option added in 7.17.1.)
+.IP CURLOPT_OPENSOCKETDATA
+Pass a pointer that will be untouched by libcurl and passed as the first
+argument in the opensocket callback set with \fICURLOPT_OPENSOCKETFUNCTION\fP.
+(Option added in 7.17.1.)
+.IP CURLOPT_CLOSESOCKETFUNCTION
+Pass a pointer to a function that matches the following prototype: \fBint
+function(void *clientp, curl_socket_t item);\fP. This function gets called by
+libcurl instead of the \fIclose(3)\fP or \fIclosesocket(3)\fP call when
+sockets are closed (not for any other file descriptors). This is pretty much
+the reverse to the \fICURLOPT_OPENSOCKETFUNCTION\fP option. Return 0 to signal
+success and 1 if there was an error.  (Option added in 7.21.7)
+.IP CURLOPT_CLOSESOCKETDATA
+Pass a pointer that will be untouched by libcurl and passed as the first
+argument in the closesocket callback set with
+\fICURLOPT_CLOSESOCKETFUNCTION\fP.  (Option added in 7.21.7)
+.IP CURLOPT_PROGRESSFUNCTION
+Pass a pointer to a function that matches the following prototype: \fBint
+function(void *clientp, double dltotal, double dlnow, double ultotal, double
+ulnow); \fP. This function gets called by libcurl instead of its internal
+equivalent with a frequent 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
+\fICURLE_ABORTED_BY_CALLBACK\fP.
+
+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.
+
+\fICURLOPT_NOPROGRESS\fP must be set to 0 to make this function actually
+get called.
+.IP CURLOPT_PROGRESSDATA
+Pass a pointer that will be untouched by libcurl and passed as the first
+argument in the progress callback set with \fICURLOPT_PROGRESSFUNCTION\fP.
+.IP CURLOPT_HEADERFUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBsize_t function( void *ptr, size_t size, size_t nmemb, void
+*userdata);\fP. 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 \fIptr\fP is
+\fIsize\fP multiplied with \fInmemb\fP. Do not assume that the header line is
+zero terminated! The pointer named \fIuserdata\fP is the one you set with the
+\fICURLOPT_WRITEHEADER\fP 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 signal an error to the library. This will abort the
+transfer and return \fICURL_WRITE_ERROR\fP.
+
+A complete HTTP header that is passed to this function can be up to
+\fICURL_MAX_HTTP_HEADER\fP (100K) bytes.
+
+If this option is not set, or if it is set to NULL, but
+\fICURLOPT_HEADERDATA\fP (\fICURLOPT_WRITEHEADER\fP) 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 \fICURLOPT_WRITEFUNCTION\fP, 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.
+.IP CURLOPT_WRITEHEADER
+(This option is also known as \fBCURLOPT_HEADERDATA\fP) Pass a pointer to be
+used to write the header part of the received data to. If you don't use
+\fICURLOPT_WRITEFUNCTION\fP or \fICURLOPT_HEADERFUNCTION\fP 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 \fICURLOPT_HEADERFUNCTION\fP option above on
+how to set a custom get-all-headers callback.
+.IP CURLOPT_DEBUGFUNCTION
+Pass a pointer to a function that matches the following prototype: \fBint
+curl_debug_callback (CURL *, curl_infotype, char *, size_t, void *);\fP
+\fICURLOPT_DEBUGFUNCTION\fP replaces the standard debug function used when
+\fICURLOPT_VERBOSE \fP is in effect. This callback receives debug information,
+as specified with the \fBcurl_infotype\fP 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:
+.RS
+.IP CURLINFO_TEXT
+The data is informational text.
+.IP CURLINFO_HEADER_IN
+The data is header (or header-like) data received from the peer.
+.IP CURLINFO_HEADER_OUT
+The data is header (or header-like) data sent to the peer.
+.IP CURLINFO_DATA_IN
+The data is protocol data received from the peer.
+.IP CURLINFO_DATA_OUT
+The data is protocol data sent to the peer.
+.RE
+.IP CURLOPT_DEBUGDATA
+Pass a pointer to whatever you want passed in to your
+\fICURLOPT_DEBUGFUNCTION\fP in the last void * argument. This pointer is not
+used by libcurl, it is only passed to the callback.
+.IP 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:
+\fBCURLcode sslctxfun(CURL *curl, void *sslctx, void *parm);\fP 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
+\fIsslctx\fP parameter is actually a pointer to an openssl \fISSL_CTX\fP. 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 function.  Set
+the \fIparm\fP argument with the \fICURLOPT_SSL_CTX_DATA\fP 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.
+.IP CURLOPT_SSL_CTX_DATA
+Data pointer to pass to the ssl context callback set by the option
+\fICURLOPT_SSL_CTX_FUNCTION\fP, this is the pointer you'll get as third
+parameter, otherwise \fBNULL\fP. (Added in 7.11.0)
+.IP CURLOPT_CONV_TO_NETWORK_FUNCTION
+.IP CURLOPT_CONV_FROM_NETWORK_FUNCTION
+.IP CURLOPT_CONV_FROM_UTF8_FUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBCURLcode function(char *ptr, size_t length);\fP
+
+These three options apply to non-ASCII platforms only.  They are available
+only if \fBCURL_DOES_CONVERSIONS\fP was defined when libcurl was built. When
+this is the case, \fIcurl_version_info(3)\fP 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.
+
+\fBCURLOPT_CONV_TO_NETWORK_FUNCTION\fP and
+\fBCURLOPT_CONV_FROM_NETWORK_FUNCTION\fP convert between the host encoding and
+the network encoding.  They are used when commands or ASCII data are
+sent/received over the network.
+
+\fBCURLOPT_CONV_FROM_UTF8_FUNCTION\fP is called to convert from UTF8 into the
+host encoding.  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
+follows:
+
+ \&#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.
+.IP CURLOPT_INTERLEAVEFUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBsize_t function( void *ptr, size_t size, size_t nmemb, void
+*userdata)\fP. 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 network byte
+order. See \fIRFC2326 Section 10.12\fP for more information on how RTP
+interleaving 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 processing may become unreasonably delayed and the
+connection may close. The application may use \fICURL_RTSPREQ_RECEIVE\fP to
+service RTP data when no requests are desired. If the application makes a
+request, (e.g.  \fICURL_RTSPREQ_PAUSE\fP) then the response handler will
+process any pending RTP data before marking the request as finished.  (Added
+in 7.20.0)
+.IP CURLOPT_INTERLEAVEDATA
+This is the userdata pointer that will be passed to
+\fICURLOPT_INTERLEAVEFUNCTION\fP when interleaved RTP data is received. (Added
+in 7.20.0)
+.IP CURLOPT_CHUNK_BGN_FUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBlong function (const void *transfer_info, void *ptr, int remains)\fP. 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 \fICURLOPT_WILDCARDMATCH\fP
+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
+\fIcurl/curl.h\fP).  The parameter ptr is a pointer given by
+\fICURLOPT_CHUNK_DATA\fP. The parameter remains contains number of chunks
+remaining per the transfer. If the feature is not available, the parameter has
+zero value.
+
+Return \fICURL_CHUNK_BGN_FUNC_OK\fP if everything is fine,
+\fICURL_CHUNK_BGN_FUNC_SKIP\fP if you want to skip the concrete chunk or
+\fICURL_CHUNK_BGN_FUNC_FAIL\fP to tell libcurl to stop if some error occurred.
+(This was added in 7.21.0)
+.IP CURLOPT_CHUNK_END_FUNCTION
+Pass a pointer to a function that matches the following prototype:
+\fBlong function(void *ptr)\fP. This function gets called by libcurl as soon
+as a part of the stream has been transferred (or skipped).
+
+Return \fICURL_CHUNK_END_FUNC_OK\fP if everything is fine or
+\fBCURL_CHUNK_END_FUNC_FAIL\fP to tell the lib to stop if some error occurred.
+(This was added in 7.21.0)
+.IP CURLOPT_CHUNK_DATA
+Pass a pointer that will be untouched by libcurl and passed as the ptr
+argument to the \fICURL_CHUNK_BGN_FUNTION\fP and \fICURL_CHUNK_END_FUNTION\fP.
+(This was added in 7.21.0)
+.IP CURLOPT_FNMATCH_FUNCTION
+Pass a pointer to a function that matches the following prototype: \fBint
+function(void *ptr, const char *pattern, const char *string)\fP prototype (see
+\fIcurl/curl.h\fP). It is used internally for the wildcard matching feature.
+
+Return \fICURL_FNMATCHFUNC_MATCH\fP if pattern matches the string,
+\fICURL_FNMATCHFUNC_NOMATCH\fP if not or \fICURL_FNMATCHFUNC_FAIL\fP if an
+error occurred.  (This was added in 7.21.0)
+.IP CURLOPT_FNMATCH_DATA
+Pass a pointer that will be untouched by libcurl and passed as the ptr argument
+to the \fICURL_FNMATCH_FUNCTION\fP. (This was added in 7.21.0)
+.SH ERROR OPTIONS
+.IP 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
+\fIcurl_easy_perform\fP. 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 \fIcurl_easy_cleanup(3)\fP or you
+set the same option again to use a different pointer.
+
+Use \fICURLOPT_VERBOSE\fP and \fICURLOPT_DEBUGFUNCTION\fP to better
+debug/trace why errors happen.
+
+If the library does not return an error, the buffer may not have been
+touched. Do not rely on the contents in those cases.
+
+.IP CURLOPT_STDERR
+Pass a FILE * as parameter. Tell libcurl to use this stream instead of stderr
+when showing the progress meter and displaying \fICURLOPT_VERBOSE\fP data.
+.IP 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 normally, 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.
+.SH NETWORK OPTIONS
+.IP 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
+(\fICURLE_UNSUPPORTED_PROTOCOL\fP) when you call \fIcurl_easy_perform(3)\fP
+or \fIcurl_multi_perform(3)\fP. Use \fIcurl_version_info(3)\fP for detailed
+information on which protocols are supported.
+
+The host part of the URL contains the address of the server that you want to
+connect to. This can be the fully qualified domain name of the server, the
+local network name of the machine on your network or the IP address of the
+server or machine represented by either an IPv4 or IPv6 address. For example:
+
+http://www.example.com/
+
+http://hostname/
+
+http://192.168.0.1/
+
+http://[2001:1890:1112:1::20]/
+
+It is also possible to specify the user name 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
+alternative mail port.
+
+The path part of the URL is protocol specific and whilst some examples are
+given below this list is not conclusive:
+
+.B HTTP
+
+The path part of a HTTP request specifies the file to retrieve and from what
+directory. If the directory is not specified then the web server's root
+directory is used. If the file is omitted then the default document will be
+retrieved for either the directory specified or the root directory. The
+exact resource returned for each URL is entirely dependent on the server's
+configuration.
+
+http://www.example.com - This gets the main page from the web server.
+
+http://www.example.com/index.html - This returns the main page by explicitly
+requesting it.
+
+http://www.example.com/contactus/ - This returns the default document from
+the contactus directory.
+
+.B FTP
+
+The path part of an FTP request specifies the file to retrieve and from what
+directory. If the file part is omitted then libcurl downloads the directory
+listing for the directory specified. If the directory is omitted then
+the directory listing for the root / home directory will be returned.
+
+ftp://ftp.example.com - This retrieves the directory listing for the root
+directory.
+
+ftp://ftp.example.com/readme.txt - This downloads the file readme.txt from the
+root directory.
+
+ftp://ftp.example.com/libcurl/readme.txt - This downloads readme.txt from the
+libcurl directory.
+
+ftp://user:password@ftp.example.com/readme.txt - This retrieves the readme.txt
+file from the user's home directory. When a username and password is
+specified, everything that is specified in the path part is relative to the
+user's home directory. To retrieve files from the root directory or a
+directory underneath the root directory then the absolute path must be
+specified by prepending an additional forward slash to the beginning of the
+path.
+
+ftp://user:password@ftp.example.com//readme.txt - This retrieves the readme.txt
+from the root directory when logging in as a specified user.
+
+.B SMTP
+
+The path part of a SMTP request specifies the host name to present during
+communication with the mail server. If the path is omitted then libcurl will
+attempt to resolve the local computer's host name. However, this may not
+return the fully qualified domain name that is required by some mail servers
+and specifying this path allows you to set an alternative name, such as
+your machine's fully qualified domain name, which you might have obtained
+from an external function such as gethostname or getaddrinfo.
+
+smtp://mail.example.com - This connects to the mail server at example.com and
+sends your local computer's host name in the HELO / EHLO command.
+
+smtp://mail.example.com/client.example.com - This will send client.example.com in
+the HELO / EHLO command to the mail server at example.com.
+
+.B 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
+
+.B SCP
+
+The path part of a SCP request specifies the file to retrieve and from what
+directory. The file part may not be omitted. The file is taken as an absolute
+path from the root directory on the server. To specify a path relative to
+the user's home directory on the server, prepend ~/ to the path portion.
+If the user name is not embedded in the URL, it can be set with the
+\fICURLOPT_USERPWD\fP or \fBCURLOPT_USERNAME\fP 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
+
+.B SFTP
+
+The path part of a SFTP request specifies the file to retrieve and from what
+directory. If the file part is omitted then libcurl downloads the directory
+listing for the directory specified.  If the path ends in a / then a directory
+listing is returned instead of a file.  If the path is omitted entirely then
+the directory listing for the root / home directory will be returned.
+If the user name is not embedded in the URL, it can be set with the
+\fICURLOPT_USERPWD\fP or \fBCURLOPT_USERNAME\fP option.
+
+sftp://user:password@example.com/etc/issue - This specifies the file
+/etc/issue
+
+sftp://user@example.com/~/my-file - This specifies the file my-file in the
+user's home directory
+
+sftp://ssh.example.com/~/Documents/ - This requests a directory listing
+of the Documents directory under the user's home directory
+
+.B 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.
+
+.B 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.
+
+\fICURLOPT_URL\fP is the only option that \fBmust\fP be set before
+\fIcurl_easy_perform(3)\fP is called.
+
+\fICURLOPT_PROTOCOLS\fP can be used to limit what protocols libcurl will use
+for this transfer, independent of what libcurl has been compiled to
+support. That may be useful if you accept the URL from an external source and
+want to limit the accessibility.
+.IP CURLOPT_PROTOCOLS
+Pass a long that holds a bitmask of CURLPROTO_* defines. If used, this bitmask
+limits 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
+transfers to only be allowed to use a subset of them. By default libcurl will
+accept all protocols it supports. See also
+\fICURLOPT_REDIR_PROTOCOLS\fP. (Added in 7.19.4)
+.IP CURLOPT_REDIR_PROTOCOLS
+Pass a long that holds a bitmask of CURLPROTO_* defines. If used, this bitmask
+limits what protocols libcurl may use in a transfer that it follows to in a
+redirect when \fICURLOPT_FOLLOWLOCATION\fP 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)
+.IP 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.
+\fICURLOPT_PROXYPORT\fP.
+
+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
+\fICURLOPT_QUOTE\fP and similar FTP specifics that don't work unless you
+tunnel through the HTTP proxy. Such tunneling is activated with
+\fICURLOPT_HTTPPROXYTUNNEL\fP.
+
+libcurl respects the environment variables \fBhttp_proxy\fP, \fBftp_proxy\fP,
+\fBall_proxy\fP etc, if any of those are set. The \fICURLOPT_PROXY\fP 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 \fICURLOPT_PROXY\fP,
+include protocol prefix (http://) and embedded user + password.
+
+Since 7.21.7, the proxy string may be specified with a protocol:// prefix to
+specify 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 proxies.
+.IP CURLOPT_PROXYPORT
+Pass a long with this option to set the proxy port to connect to unless it is
+specified in the proxy string \fICURLOPT_PROXY\fP.
+.IP CURLOPT_PROXYTYPE
+Pass a long with this option to set type of the proxy. Available options for
+this are \fICURLPROXY_HTTP\fP, \fICURLPROXY_HTTP_1_0\fP (added in 7.19.4),
+\fICURLPROXY_SOCKS4\fP (added in 7.10), \fICURLPROXY_SOCKS5\fP,
+\fICURLPROXY_SOCKS4A\fP (added in 7.18.0) and \fICURLPROXY_SOCKS5_HOSTNAME\fP
+(added in 7.18.0). The HTTP type is default. (Added in 7.10)
+
+If you set \fBCURLOPT_PROXYTYPE\fP to \fICURLPROXY_HTTP_1_0\fP, 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
+\fICURLOPT_HTTP_VERSION\fP.
+.IP CURLOPT_NOPROXY
+Pass a pointer to a zero terminated string. The string consists of a comma
+separated 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)
+.IP 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.
+.IP 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)
+.IP 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).
+.IP 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.
+.IP CURLOPT_LOCALPORT
+Pass a long. This sets the local port number of the socket used for
+connection. This can be used in combination with \fICURLOPT_INTERFACE\fP and
+you are recommended to use \fICURLOPT_LOCALPORTRANGE\fP as well when this is
+set. Valid port numbers are 1 - 65535. (Added in 7.15.2)
+.IP 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 \fICURLOPT_LOCALPORT\fP
+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)
+.IP 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
+\fIres_init(3)\fP). 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.
+.IP 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.
+
+\fBWARNING:\fP this option is considered obsolete. Stop using it. Switch over
+to using the share interface instead! See \fICURLOPT_SHARE\fP and
+\fIcurl_share_init(3)\fP.
+.IP 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.
+.IP 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.
+.IP 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
+algorithm 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.
+.IP 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)
+.IP CURLOPT_TCP_KEEPALIVE
+Pass a long. If set to 1, TCP keepalive probes will be sent. The delay and
+frequency of these probes can be controlled by the \fICURLOPT_TCP_KEEPIDLE\fP
+and \fICURLOPT_TCP_KEEPINTVL\fP options, provided the operating system supports
+them. Set to 0 (default behavior) to disable keepalive probes (Added in
+7.25.0).
+.IP 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)
+.IP 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)
+.SH NAMES and PASSWORDS OPTIONS (Authentication)
+.IP CURLOPT_NETRC
+This parameter controls the preference of libcurl between using user names and
+passwords from your \fI~/.netrc\fP file, relative to user names and passwords
+in the URL supplied with \fICURLOPT_URL\fP.
+
+libcurl uses a user name (and supplied or prompted password) supplied with
+\fICURLOPT_USERPWD\fP in preference to any of the options controlled by this
+parameter.
+
+Pass a long, set to one of the values described below.
+.RS
+.IP CURL_NETRC_OPTIONAL
+The use of your \fI~/.netrc\fP 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 \fImachine\fP, which ever information is not specified in
+the URL.
+
+Undefined values of the option will have this effect.
+.IP CURL_NETRC_IGNORED
+The library will ignore the file and use only the information in the URL.
+
+This is the default.
+.IP 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.
+.RE
+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.
+.IP 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 \fICURLOPT_NETRC\fP is set, libcurl will attempt to
+find a .netrc file in the current user's home directory. (Added in 7.10.9)
+.IP CURLOPT_USERPWD
+Pass a char * as parameter, which should be [user name]:[password] to use for
+the connection. Use \fICURLOPT_HTTPAUTH\fP to decide the authentication method.
+
+When using NTLM, you can set the domain by prepending it to the user name and
+separating 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 \fICURLOPT_FOLLOWLOCATION\fP, libcurl might perform
+several requests to possibly different hosts. libcurl will only send this user
+and password information to hosts using the initial host name (unless
+\fICURLOPT_UNRESTRICTED_AUTH\fP 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.
+.IP CURLOPT_PROXYUSERPWD
+Pass a char * as parameter, which should be [user name]:[password] to use for
+the connection to the HTTP proxy.  Use \fICURLOPT_PROXYAUTH\fP to decide
+the authentication method.
+.IP CURLOPT_USERNAME
+Pass a char * as parameter, which should be pointing to the zero terminated
+user name to use for the transfer.
+
+\fBCURLOPT_USERNAME\fP 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 \fICURLOPT_PASSWORD\fP option.  (Added in 7.19.1)
+.IP CURLOPT_PASSWORD
+Pass a char * as parameter, which should be pointing to the zero terminated
+password to use for the transfer.
+
+The CURLOPT_PASSWORD option should be used in conjunction with
+the \fICURLOPT_USERNAME\fP option. (Added in 7.19.1)
+.IP 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
+\fICURLOPT_PROXYUSERPWD\fP is used.  In comparison to
+\fICURLOPT_PROXYUSERPWD\fP 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
+\fICURLOPT_PROXYUSERPWD\fP option.
+
+In order to specify the password to be used in conjunction with the user name
+use the \fICURLOPT_PROXYPASSWORD\fP option.  (Added in 7.19.1)
+.IP CURLOPT_PROXYPASSWORD
+Pass a char * as parameter, which should be pointing to the zero terminated
+password to use for the transfer while connecting to Proxy.
+
+The CURLOPT_PROXYPASSWORD option should be used in conjunction with
+the \fICURLOPT_PROXYUSERNAME\fP option. (Added in 7.19.1)
+.IP CURLOPT_HTTPAUTH
+Pass a long as parameter, which is set to a bitmask, to tell libcurl which
+authentication 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 methods, this will induce an extra network round-trip. Set
+the actual name and password with the \fICURLOPT_USERPWD\fP option or
+with the \fICURLOPT_USERNAME\fP and the \fICURLOPT_PASSWORD\fP options.
+(Added in 7.10.6)
+.RS
+.IP 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.
+.IP 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
+regular old-fashioned Basic method.
+.IP 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 simply
+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)
+.IP 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 authentication
+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.
+.IP CURLAUTH_NTLM
+HTTP NTLM authentication. A proprietary protocol invented and used by
+Microsoft. 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.
+.IP 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 \fICURLOPT_NOSIGNAL\fP 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.
+.IP 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.
+.IP 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.
+.IP 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)
+.RE
+.IP CURLOPT_TLSAUTH_TYPE
+Pass a long as parameter, which is set to a bitmask, to tell libcurl which
+authentication method(s) you want it to use for TLS authentication.
+.RS
+.IP 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
+\fICURLOPT_TLSAUTH_USERNAME\fP and \fICURLOPT_TLSAUTH_PASSWORD\fP options.
+
+You need to build libcurl with GnuTLS or OpenSSL with TLS-SRP support for this
+to work. (Added in 7.21.4)
+.RE
+.IP 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
+\fICURLOPT_TLSAUTH_TYPE\fP option. Requires that the
+\fICURLOPT_TLS_PASSWORD\fP option also be set. (Added in 7.21.4)
+.IP 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
+\fICURLOPT_TLSAUTH_TYPE\fP option. Requires that the
+\fICURLOPT_TLS_USERNAME\fP option also be set. (Added in 7.21.4)
+.IP CURLOPT_PROXYAUTH
+Pass a long as parameter, which is set to a bitmask, to tell libcurl which
+authentication 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 methods 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 \fICURLOPT_PROXYUSERPWD\fP option. The
+bitmask can be constructed by or'ing together the bits listed above for the
+\fICURLOPT_HTTPAUTH\fP option. As of this writing, only Basic, Digest and NTLM
+work. (Added in 7.10.7)
+.SH HTTP OPTIONS
+.IP 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.
+.IP 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: \fIidentity\fP, which does nothing,
+\fIdeflate\fP which requests the server to compress its response using the
+zlib algorithm, and \fIgzip\fP 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)
+.IP 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
+\fBCURLOPT_ACCEPT_ENCODING\fP 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. Traditionally, Transfer-Encoding has been much less used and supported
+by both HTTP clients and HTTP servers.
+
+(Added in 7.21.6)
+.IP 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. \fICURLOPT_MAXREDIRS\fP 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 \fICURLOPT_REDIR_PROTOCOLS\fP and
+it excludes the FILE protocol by default.
+.IP 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 \fICURLOPT_FOLLOWLOCATION\fP.
+.IP CURLOPT_MAXREDIRS
+Pass a long. The set number will be the redirection limit. If that many
+redirections have been followed, the next redirect will cause an error
+(\fICURLE_TOO_MANY_REDIRECTS\fP). This option only makes sense if the
+\fICURLOPT_FOLLOWLOCATION\fP 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)
+.IP 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
+\fBCURL_REDIR_POST_301\fP) 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 \fBCURL_REDIR_POST_302\fP) makes libcurl maintain the
+request method after a 302 redirect whilst setting bit 2 (value
+\fBCURL_REDIR_POST_303\fP) makes libcurl maintain the request method after a
+303 redirect. The value \fBCURL_REDIR_POST_ALL\fP is a convenience define that
+sets all three bits.
+
+The non-RFC behaviour is ubiquitous in web browsers, so the library does the
+conversion 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 \fICURLOPT_FOLLOWLOCATION\fP.  (Added in 7.17.1) (This option was
+known as CURLOPT_POST301 up to 7.19.0 as it only supported the 301 then)
+.IP CURLOPT_PUT
+A parameter set to 1 tells the library to use HTTP PUT to transfer data. The
+data should be set with \fICURLOPT_READDATA\fP and \fICURLOPT_INFILESIZE\fP.
+
+This option is deprecated and starting with version 7.12.1 you should instead
+use \fICURLOPT_UPLOAD\fP.
+.IP 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 \fICURLOPT_POSTFIELDS\fP or \fICURLOPT_COPYPOSTFIELDS\fP options to
+specify what data to post and \fICURLOPT_POSTFIELDSIZE\fP or
+\fICURLOPT_POSTFIELDSIZE_LARGE\fP to set the data size.
+
+Optionally, you can provide data to POST using the \fICURLOPT_READFUNCTION\fP
+and \fICURLOPT_READDATA\fP options but then you must make sure to not set
+\fICURLOPT_POSTFIELDS\fP 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 \fICURLOPT_POSTFIELDSIZE\fP or
+\fICURLOPT_POSTFIELDSIZE_LARGE\fP option. To enable chunked encoding, 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 \fICURLOPT_HTTPHEADER\fP.
+
+Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header.
+You can disable this header with \fICURLOPT_HTTPHEADER\fP 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
+\fICURLOPT_HTTPHEADER\fP. With HTTP 1.0 or without chunked transfer, you must
+specify the size in the request.
+
+When setting \fICURLOPT_POST\fP to 1, it will automatically set
+\fICURLOPT_NOBODY\fP 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
+\fICURLOPT_NOBODY\fP or \fICURLOPT_HTTPGET\fP or similar.
+.IP 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 preserved 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 \fICURLOPT_POST\fP. Using
+\fICURLOPT_POSTFIELDS\fP implies \fICURLOPT_POST\fP.
+
+If you want to do a zero-byte POST, you need to set
+\fICURLOPT_POSTFIELDSIZE\fP explicitly to zero, as simply setting
+\fICURLOPT_POSTFIELDS\fP 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 \fICURLOPT_HTTPHEADER\fP as usual.
+
+To make multipart/formdata posts (aka RFC2388-posts), check out the
+\fICURLOPT_HTTPPOST\fP option.
+.IP 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.
+.IP CURLOPT_POSTFIELDSIZE_LARGE
+Pass a curl_off_t as parameter. Use this to set the size of the
+\fICURLOPT_POSTFIELDS\fP data to prevent libcurl from doing strlen() on the
+data to figure out the size. This is the large file version of the
+\fICURLOPT_POSTFIELDSIZE\fP option. (Added in 7.11.1)
+.IP CURLOPT_COPYPOSTFIELDS
+Pass a char * as parameter, which should be the full data to post in a HTTP
+POST operation. It behaves as the \fICURLOPT_POSTFIELDS\fP 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 \fICURLOPT_POSTFIELDSIZE\fP or
+\fICURLOPT_POSTFIELDSIZE_LARGE\fP: If the size has not been set prior to
+\fICURLOPT_COPYPOSTFIELDS\fP, 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
+\fICURLOPT_COPYPOSTFIELDS\fP, unless another \fICURLOPT_POSTFIELDS\fP or
+\fICURLOPT_COPYPOSTFIELDS\fP option is issued.
+(Added in 7.17.1)
+.IP 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_httppost structs as parameter.  The easiest way to create such a
+list, is to use \fIcurl_formadd(3)\fP as documented. The data in this list
+must remain intact until you close this curl handle again with
+\fIcurl_easy_cleanup(3)\fP.
+
+Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header.
+You can disable this header with \fICURLOPT_HTTPHEADER\fP as usual.
+
+When setting \fICURLOPT_HTTPPOST\fP, it will automatically set
+\fICURLOPT_NOBODY\fP to 0 (since 7.14.1).
+.IP 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 \fICURLOPT_HTTPHEADER\fP.
+.IP 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 \fICURLOPT_HTTPHEADER\fP.
+.IP 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 \fBstruct
+curl_slist\fP structs properly filled in. Use \fIcurl_slist_append(3)\fP to
+create the list and \fIcurl_slist_free_all(3)\fP to clean up an entire
+list. If you add a header that is otherwise 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 headers. To add a
+header with no content, make the content be two quotes: \&"". The headers
+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
+\fICURLOPT_COOKIE\fP, \fICURLOPT_USERAGENT\fP and \fICURLOPT_REFERER\fP.
+.IP 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 \fIcurl_slist_append(3)\fP to create the list and
+\fIcurl_slist_free_all(3)\fP 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 \fICURLOPT_HTTP_VERSION\fP, but starting
+with 7.16.3 the protocol is assumed to match HTTP 1.0 when an alias matched.
+.IP 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 cookies in one string like this: "name1=content1; name2=content2;"
+etc.
+
+This option sets the cookie header explicitly in the outgoing request(s). If
+multiple 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
+previous ones.
+.IP 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.
+.IP CURLOPT_COOKIEJAR
+Pass a file name as char *, zero terminated. This will make libcurl write all
+internally known cookies to the specified file when \fIcurl_easy_cleanup(3)\fP
+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
+\fIcurl_easy_cleanup(3)\fP is called), libcurl will not and cannot report an
+error for this. Using \fICURLOPT_VERBOSE\fP or \fICURLOPT_DEBUGFUNCTION\fP
+will get a warning to display, but that is the only visible feedback you get
+about this possibly lethal situation.
+.IP 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 previous 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.
+.IP 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 specified by \fICURLOPT_COOKIEJAR\fP.
+(Added in 7.17.1)
+.IP 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 \fICURLOPT_HTTPGET\fP to 1, it will automatically set
+\fICURLOPT_NOBODY\fP to 0 (since 7.14.1).
+.IP 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 reason.
+.RS
+.IP CURL_HTTP_VERSION_NONE
+We don't care about what version the library uses. libcurl will use whatever
+it thinks fit.
+.IP CURL_HTTP_VERSION_1_0
+Enforce HTTP 1.0 requests.
+.IP CURL_HTTP_VERSION_1_1
+Enforce HTTP 1.1 requests.
+.RE
+.IP 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)
+.IP 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 content decoding but requires you to use \fICURLOPT_ENCODING\fP for
+that. (added in 7.16.2)
+.IP CURLOPT_HTTP_TRANSFER_DECODING
+Pass a long to tell libcurl how to act on transfer decoding. If set to zero,
+transfer 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)
+.SH SMTP OPTIONS
+.IP 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)
+.IP 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 \fBstruct
+curl_slist\fP structs properly filled in. Use \fIcurl_slist_append(3)\fP to
+create the list and \fIcurl_slist_free_all(3)\fP 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)
+.IP CURLOPT_MAIL_AUTH
+Pass a pointer to a zero terminated string as parameter. This will be used
+to specify 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
+communicate the authentication of individual messages and should only be used
+by the application program, using libcurl, if the application is itself a
+mail server acting 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)
+.SH TFTP OPTIONS
+.IP 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 specified. 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)
+.SH FTP OPTIONS
+.IP 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 available, 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:
+
+.nf
+  eth0:0
+  192.168.1.2:32000-33000
+  curl.se:32123
+  [::1]:1234-4567
+.fi
+
+You disable PORT again and go back to using the passive version by setting
+this option to NULL.
+.IP 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 \fIcurl_slist_append(3)\fP to append strings (commands) to the
+list, and clear the entire list afterwards with
+\fIcurl_slist_free_all(3)\fP. Disable this operation again by setting 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 command
+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
+.BR curl (1))
+(SFTP support added in 7.16.3)
+.IP 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 \fICURLOPT_QUOTE\fP. Disable this
+operation again by setting a NULL to this option.
+.IP 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
+\fICURLOPT_QUOTE\fP. Disable this operation again by setting a NULL to this
+option. Before version 7.16.0, if you also set \fICURLOPT_NOBODY\fP to 1, this
+option didn't work.
+.IP CURLOPT_DIRLISTONLY
+A parameter set to 1 tells the library to just list the names of files in a
+directory, 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
+subdirectories 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 \fICURLOPT_WILDCARDMATCH\fP as it will
+effectively break that feature then.
+
+(This option was known as CURLOPT_FTPLISTONLY up to 7.16.4)
+.IP 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)
+.IP 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
+\fICURLOPT_FTPPORT\fP). 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.
+.IP 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.
+.IP 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)
+.IP 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 connection does MKD before this connection and thus MKD fails
+but trying CWD works! 7.19.4 also introduced the \fICURLFTP_CREATE_DIR\fP and
+\fICURLFTP_CREATE_DIR_RETRY\fP 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.
+.IP 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 \fICURLOPT_TIMEOUT\fP. It is
+recommended that if used in conjunction with \fICURLOPT_TIMEOUT\fP, you set
+\fICURLOPT_FTP_RESPONSE_TIMEOUT\fP to a value smaller than
+\fICURLOPT_TIMEOUT\fP.  (Added in 7.10.8)
+.IP 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 currently only known to be required when connecting to
+Tumbleweed's Secure Transport FTPS server using client certificates for
+authentication. (Added in 7.15.5)
+.IP 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.
+.IP 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
+\fICURLOPT_USE_SSL\fP). (Added in 7.12.2)
+.RS
+.IP CURLFTPAUTH_DEFAULT
+Allow libcurl to decide.
+.IP CURLFTPAUTH_SSL
+Try "AUTH SSL" first, and only if that fails try "AUTH TLS".
+.IP CURLFTPAUTH_TLS
+Try "AUTH TLS" first, and only if that fails try "AUTH SSL".
+.RE
+.IP 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 communication will be unencrypted. This allows NAT routers
+to follow the FTP transaction. Pass a long using one of the values below.
+(Added in 7.16.1)
+.RS
+.IP CURLFTPSSL_CCC_NONE
+Don't attempt to use CCC.
+.IP CURLFTPSSL_CCC_PASSIVE
+Do not initiate the shutdown, but wait for the server to do it. Do not send
+a reply.
+.IP CURLFTPSSL_CCC_ACTIVE
+Initiate the shutdown and wait for a reply.
+.RE
+.IP 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)
+.IP 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:
+.RS
+.IP 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.
+.IP 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 behavior.
+.IP 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'.
+.RE
+(Added in 7.15.1)
+.SH RTSP OPTIONS
+.IP 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)
+.RS
+.IP CURL_RTSPREQ_OPTIONS
+Used to retrieve the available methods of the server. The application is
+responsible for parsing and obeying the response. \fB(The session ID is not
+needed for this method.)\fP  (Added in 7.20.0)
+.IP CURL_RTSPREQ_DESCRIBE
+Used to get the low level description of a stream. The application should note
+what formats it understands in the \fI'Accept:'\fP header. Unless set
+manually, libcurl will automatically fill in \fI'Accept:
+application/sdp'\fP. Time-condition headers will be added to Describe requests
+if the \fICURLOPT_TIMECONDITION\fP option is active. \fB(The session ID is not
+needed for this method)\fP  (Added in 7.20.0)
+.IP 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
+\fICURL_RTSPREQ_SET_PARAMETER\fP (Added in 7.20.0)
+.IP CURL_RTSPREQ_SETUP
+Setup is used to initialize the transport layer for the session. The
+application must set the desired Transport options for a session by using the
+\fICURLOPT_RTSP_TRANSPORT\fP option prior to calling setup. If no session ID
+is currently set with \fICURLOPT_RTSP_SESSION_ID\fP, libcurl will extract and
+use the session ID in the response to this request. \fB(The session ID is not
+needed for this method).\fP  (Added in 7.20.0)
+.IP CURL_RTSPREQ_PLAY
+Send a Play command to the server. Use the \fICURLOPT_RANGE\fP option to
+modify the playback time (e.g. 'npt=10-15').  (Added in 7.20.0)
+.IP CURL_RTSPREQ_PAUSE
+Send a Pause command to the server. Use the \fICURLOPT_RANGE\fP option with a
+single value to indicate when the stream should be halted. (e.g. npt='25')
+(Added in 7.20.0)
+.IP 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)
+.IP CURL_RTSPREQ_GET_PARAMETER
+Retrieve a parameter from the server. By default, libcurl will automatically
+include a \fIContent-Type: text/parameters\fP header on all non-empty requests
+unless a custom one is set. GET_PARAMETER acts just like a HTTP PUT or POST
+(see \fICURL_RTSPREQ_SET_PARAMETER\fP).
+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)
+.IP CURL_RTSPREQ_SET_PARAMETER
+Set a parameter on the server. By default, libcurl will automatically include
+a \fIContent-Type: text/parameters\fP header unless a custom one is set. The
+interaction with SET_PARAMTER is much like a HTTP PUT or POST. An application
+may either use \fICURLOPT_UPLOAD\fP with \fICURLOPT_READDATA\fP like a HTTP
+PUT, or it may use \fICURLOPT_POSTFIELDS\fP like a HTTP POST. No chunked
+transfers are allowed, so the application must set the
+\fICURLOPT_INFILESIZE\fP in the former and \fICURLOPT_POSTFIELDSIZE\fP in the
+latter. Also, there is no use of multi-part POSTs within RTSP. (Added in
+7.20.0)
+.IP CURL_RTSPREQ_RECORD
+Used to tell the server to record a session. Use the \fICURLOPT_RANGE\fP
+option to modify the record time. (Added in 7.20.0)
+.IP 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)
+.RE
+.IP 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 \fICURLE_RTSP_SESSION_ERROR\fP
+if ID received from the server does not match. If unset (or set to NULL),
+libcurl will automatically set the ID the first time the server sets it in a
+response. (Added in 7.20.0)
+.IP CURLOPT_RTSP_STREAM_URI
+Set the stream URI to operate on by passing a char * . For example, a single
+session may be controlling \fIrtsp://foo/twister/audio\fP and
+\fIrtsp://foo/twister/video\fP 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 \fICURLOPT_URL\fP. When working with
+RTSP, the \fICURLOPT_STREAM_URI\fP indicates what URL to send to the server in
+the request header while the \fICURLOPT_URL\fP indicates where to make the
+connection to.  (e.g. the \fICURLOPT_URL\fP for the above examples might be
+set to \fIrtsp://foo/twister\fP (Added in 7.20.0)
+.IP 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)
+.IP CURLOPT_RTSP_HEADER
+This option is simply an alias for \fICURLOPT_HTTP_HEADER\fP. Use this to
+replace the standard headers that RTSP and HTTP share. It is also valid to use
+the shortcuts such as \fICURLOPT_USERAGENT\fP. (Added in 7.20.0)
+.IP 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)
+.IP 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)
+.SH PROTOCOL OPTIONS
+.IP 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.
+.IP 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), \fICURLOPT_TRANSFERTEXT\fP has no effect when doing
+FTP via a proxy. Beware that not all proxies support this feature.  (Added in
+7.18.0)
+.IP 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).
+.IP 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
+\fI"X-Y,N-M"\fP. 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 \fBnot\fP 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.
+.IP 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.
+.IP 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)
+.IP 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 \fBCURLOPT_CUSTOMREQUEST\fP 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 \fICURLOPT_NOBODY\fP, to switch to a
+proper POST use \fICURLOPT_POST\fP or \fICURLOPT_POSTFIELDS\fP 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 \fICURLOPT_NOBODY\fP 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 \fICURLOPT_POST\fP and
+\fICURLOPT_POSTFIELDS\fP to set POST data. Use \fICURLOPT_HTTPHEADER\fP to
+replace or extend the set of headers sent by libcurl. Use
+\fICURLOPT_HTTP_VERSION\fP to change HTTP version.
+
+(Support for POP3 added in 7.26.0)
+.IP 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
+\fIcurl_easy_getinfo(3)\fP function with the \fICURLINFO_FILETIME\fP argument
+can be used after a transfer to extract the received time (if any).
+.IP 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 \fICURLOPT_HTTPGET\fP. Change
+request to POST with \fICURLOPT_POST\fP etc.
+.IP 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 \fICURLOPT_INFILESIZE_LARGE\fP.
+
+For uploading using SCP, this option or \fICURLOPT_INFILESIZE_LARGE\fP 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.
+.IP 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 \fICURLOPT_INFILESIZE\fP 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.
+.IP CURLOPT_UPLOAD
+A parameter set to 1 tells the library to prepare for an upload. The
+\fICURLOPT_READDATA\fP and \fICURLOPT_INFILESIZE\fP or
+\fICURLOPT_INFILESIZE_LARGE\fP options are also interesting 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 \fICURLOPT_HTTPHEADER\fP 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
+\fICURLOPT_HTTPHEADER\fP. With HTTP 1.0 or without chunked transfer, you must
+specify the size.
+.IP 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.
+.IP 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 \fICURLE_FILESIZE_EXCEEDED\fP 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.
+.IP CURLOPT_TIMECONDITION
+Pass a long as parameter. This defines how the \fICURLOPT_TIMEVALUE\fP time
+value is treated. You can set this parameter to \fICURL_TIMECOND_IFMODSINCE\fP
+or \fICURL_TIMECOND_IFUNMODSINCE\fP. 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. \fIcurl_easy_getinfo(3)\fP with the
+\fICURLINFO_CONDITION_UNMET\fP option can be used after a transfer to learn if
+a zero-byte successful "transfer" was due to this condition not matching.
+.IP 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
+\fICURLOPT_TIMECONDITION\fP.
+.SH CONNECTION OPTIONS
+.IP 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
+\fICURLOPT_NOSIGNAL\fP is set.
+
+Default timeout is 0 (zero) which means it never times out.
+.IP CURLOPT_TIMEOUT_MS
+Like \fICURLOPT_TIMEOUT\fP 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 second.
+(Added in 7.16.2)
+.IP 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 \fICURLOPT_LOW_SPEED_TIME\fP seconds
+for the library to consider it too slow and abort.
+.IP CURLOPT_LOW_SPEED_TIME
+Pass a long as parameter. It contains the time in seconds that the transfer
+should be below the \fICURLOPT_LOW_SPEED_LIMIT\fP for the library to consider
+it too slow and abort.
+.IP 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)
+.IP 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 unlimited speed. (Added in 7.15.5)
+.IP 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 persistent 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 \fIcurl_multi_setopt(3)\fP and the
+\fICURLMOPT_MAXCONNECTS\fP option.
+.IP CURLOPT_CLOSEPOLICY
+(Obsolete) This option does nothing.
+.IP 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 behavior).
+.IP 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 transfer 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).
+.IP CURLOPT_CONNECTTIMEOUT
+Pass a long. It should contain the maximum time in seconds that you allow the
+connection 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
+\fICURLOPT_TIMEOUT\fP option.
+
+In unix-like systems, this might cause signals to be used unless
+\fICURLOPT_NOSIGNAL\fP is set.
+.IP CURLOPT_CONNECTTIMEOUT_MS
+Like \fICURLOPT_CONNECTTIMEOUT\fP but takes the number of milliseconds
+instead. If libcurl is built to use the standard system name resolver,
+that portion of the connect will still use full-second resolution for
+timeouts with a minimum timeout allowed of one second.
+(Added in 7.16.2)
+.IP 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:
+.RS
+.IP CURL_IPRESOLVE_WHATEVER
+Default, resolves addresses to all IP versions that your system allows.
+.IP CURL_IPRESOLVE_V4
+Resolve to IPv4 addresses.
+.IP CURL_IPRESOLVE_V6
+Resolve to IPv6 addresses.
+.RE
+.IP 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 \fICURLINFO_LASTSOCKET\fP option to
+\fIcurl_easy_getinfo(3)\fP 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)
+.IP 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_*)
+.RS
+.IP CURLUSESSL_NONE
+Don't attempt to use SSL.
+.IP CURLUSESSL_TRY
+Try using SSL, proceed as normal otherwise.
+.IP CURLUSESSL_CONTROL
+Require SSL for the control connection or fail with \fICURLE_USE_SSL_FAILED\fP.
+.IP CURLUSESSL_ALL
+Require SSL for all communication or fail with \fICURLE_USE_SSL_FAILED\fP.
+.RE
+.IP 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 \fBstruct curl_slist\fP structs properly filled in. Use
+\fIcurl_slist_append(3)\fP to create the list and \fIcurl_slist_free_all(3)\fP
+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)
+.IP 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)
+.IP 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)
+.SH SSL and SECURITY OPTIONS
+.IP 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 \fICURLOPT_SSLCERTTYPE\fP.
+
+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.
+.IP 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)
+.IP 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 \fICURLOPT_SSLKEYTYPE\fP.
+.IP 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 \fICURLOPT_SSLKEY\fP is used as an identifier passed to the
+engine. You have to set the crypto engine with \fICURLOPT_SSLENGINE\fP.
+\&"DER" format key file currently does not work because of a bug in OpenSSL.
+.IP CURLOPT_KEYPASSWD
+Pass a pointer to a zero terminated string as parameter. It will be used as
+the password required to use the \fICURLOPT_SSLKEY\fP or
+\fICURLOPT_SSH_PRIVATE_KEYFILE\fP 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_SSLCERTPASSWD up to 7.9.2)
+.IP 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, \fICURLE_SSL_ENGINE_NOTFOUND\fP is
+returned.
+.IP CURLOPT_SSLENGINE_DEFAULT
+Sets the actual crypto engine as the default for (asymmetric) crypto
+operations.
+
+If the crypto device cannot be set, \fICURLE_SSL_ENGINE_SETFAILED\fP is
+returned.
+
+Even though this option doesn't need any parameter, in some configurations
+\fIcurl_easy_setopt\fP might be defined as a macro taking exactly three
+arguments. Therefore, it's recommended to pass 1 as parameter to this option.
+.IP CURLOPT_SSLVERSION
+Pass a long as parameter to control what version of SSL/TLS to attempt to use.
+The available options are:
+.RS
+.IP 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).
+.IP CURL_SSLVERSION_TLSv1
+Force TLSv1
+.IP CURL_SSLVERSION_SSLv2
+Force SSLv2
+.IP CURL_SSLVERSION_SSLv3
+Force SSLv3
+.RE
+.IP 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
+certificate. 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 \fICURLOPT_CAINFO\fP option or the \fICURLOPT_CAPATH\fP
+option.
+
+When \fICURLOPT_SSL_VERIFYPEER\fP 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
+\fICURLOPT_SSL_VERIFYHOST\fP to control that. The check that the host name in
+the certificate is valid for the host name you're connecting to is done
+independently of the \fICURLOPT_SSL_VERIFYPEER\fP option.
+.IP CURLOPT_CAINFO
+Pass a char * to a zero terminated string naming a file holding one or more
+certificates to verify the peer with.  This makes sense only when used in
+combination with the \fICURLOPT_SSL_VERIFYPEER\fP option.  If
+\fICURLOPT_SSL_VERIFYPEER\fP is zero, \fICURLOPT_CAINFO\fP 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
+(libnsspem.so) needs to be available for this option to work properly.
+.IP 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
+\fICURLOPT_SSL_VERIFYPEER\fP 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 (\fICURLOPT_SSL_VERIFYPEER\fP has
+to be set too for the check to fail). (Added in 7.19.0)
+.IP 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 certificate directory must be prepared using the openssl c_rehash utility.
+This makes sense only when used in combination with the
+\fICURLOPT_SSL_VERIFYPEER\fP option.  If \fICURLOPT_SSL_VERIFYPEER\fP is zero,
+\fICURLOPT_CAPATH\fP need not even indicate an accessible path.  The
+\fICURLOPT_CAPATH\fP 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.
+.IP 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, requiring 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
+\fICURLOPT_SSL_VERIFYPEER\fP 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)
+.IP 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 \fICURLOPT_SSL_VERIFYHOST\fP 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
+certificate.
+
+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
+\fICURLOPT_SSL_VERIFYPEER\fP.  If libcurl is built against NSS and
+\fICURLOPT_SSL_VERIFYPEER\fP is zero, \fICURLOPT_SSL_VERIFYHOST\fP
+is ignored.
+
+.IP 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
+\fIcurl_easy_getinfo(3)\fP and its option \fICURLINFO_CERTINFO\fP. (Added in
+7.19.1)
+.IP 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.
+.IP 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.
+.IP 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 acceptable 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
+compile OpenSSL.
+
+You'll find more details about cipher lists on this URL:
+\fIhttp://www.openssl.org/docs/apps/ciphers.html\fP
+
+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:
+\fIhttp://git.fedorahosted.org/cgit/mod_nss.git/plain/docs/mod_nss.html#Directives\fP
+
+.IP 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 broken SSL implementations in the wild that may
+require you to disable this in order for you to succeed. (Added in 7.16.0)
+.IP 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)
+.IP 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)
+.IP CURLOPT_GSSAPI_DELEGATION
+Set the parameter to CURLGSSAPI_DELEGATION_FLAG to allow unconditional GSSAPI
+credential 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-DELEGATE 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)
+.SH SSH OPTIONS
+.IP 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. Currently 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)
+.IP 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)
+.IP CURLOPT_SSH_PUBLIC_KEYFILE
+Pass a char * pointing to a file name for your public key. If not used,
+libcurl defaults to \fB$HOME/.ssh/id_dsa.pub\fP if the HOME environment
+variable is set, and just "id_dsa.pub" in the current directory if HOME is not
+set.  (Added in 7.16.1)
+If an empty string is passed, libcurl will pass no public key to libssh2
+which then tries to compute it from the private key, this is known to work
+when libssh2 1.4.0+ is linked against OpenSSL. (Added in 7.26.0)
+.IP CURLOPT_SSH_PRIVATE_KEYFILE
+Pass a char * pointing to a file name for your private key. If not used,
+libcurl defaults to \fB$HOME/.ssh/id_dsa\fP 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-protected, set the password with
+\fICURLOPT_KEYPASSWD\fP. (Added in 7.16.1)
+.IP 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 \fICURLOPT_SSH_KEYFUNCTION\fP to alter the default
+behavior on host and key (mis)matching. (Added in 7.19.6)
+.IP 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
+\fICURLOPT_SSH_KNOWNHOSTS\fP 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 \fICURLOPT_SSH_KEYDATA\fP). It
+MUST return one of the following return codes to tell libcurl how to act:
+.RS
+.IP 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.
+.IP 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.
+.IP CURLKHSTAT_REJECT
+The host+key is rejected. libcurl will deny the connection to continue and it
+will be closed.
+.IP 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.
+.RE
+ (Added in 7.19.6)
+.IP CURLOPT_SSH_KEYDATA
+Pass a void * as parameter. This pointer will be passed along verbatim to the
+callback set with \fICURLOPT_SSH_KEYFUNCTION\fP. (Added in 7.19.6)
+.SH OTHER OPTIONS
+.IP 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
+\fIcurl_easy_getinfo(3)\fP with the CURLINFO_PRIVATE option. libcurl itself
+does nothing with this data. (Added in 7.10.3)
+.IP CURLOPT_SHARE
+Pass a share handle as a parameter. The share handle must have been created by
+a previous call to \fIcurl_share_init(3)\fP. Setting this option, will make
+this curl handle 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 simultaneously in multiple threads, you \fBMUST\fP use the
+locking methods in the share handle. See \fIcurl_share_setopt(3)\fP 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.
+.IP 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
+\fI0644\fP, but any valid value can be used.  The only protocols that can use
+this are \fIsftp://\fP, \fIscp://\fP, and \fIfile://\fP. (Added in 7.16.4)
+.IP 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 \fI0755\fP, but any valid value can be used.  The only protocols that
+can use this are \fIsftp://\fP, \fIscp://\fP, and \fIfile://\fP.
+(Added in 7.16.4)
+.SH TELNET OPTIONS
+.IP CURLOPT_TELNETOPTIONS
+Provide a pointer to a curl_slist with variables to pass to the telnet
+negotiations. The variables should be in the format <option=value>. libcurl
+supports the options 'TTYPE', 'XDISPLOC' and 'NEW_ENV'. See the TELNET
+standard for details.
+.SH RETURN VALUE
+CURLE_OK (zero) means that the option was set properly, non-zero means an
+error occurred as \fI<curl/curl.h>\fP defines. See the \fIlibcurl-errors(3)\fP
+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 \fICURLE_FAILED_INIT\fP.
+.SH "SEE ALSO"
+.BR curl_easy_init "(3), " curl_easy_cleanup "(3), " curl_easy_reset "(3)"