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curleasysetopt(3) libcurl Manual curleasysetopt(3)

NAME

curleasysetopt - set options for a curl easy handle

SYNOPSIS

#include

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

DESCRIPTION

curleasysetopt() is used to tell libcurl how to behave. By using the appropriate options to curleasysetopt, you can change libcurl's behavior. All options are set with the option followed by a parameter. That parameter can be a lloonngg, a ffuunnccttiioonn ppooiinntteerr, an oobbjjeecctt ppooiinntteerr or a ccuurrlloofffftt, 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 applica-

tion uses many curleasysetopt() calls in the setup phase. Options set with this function call are valid for all forthcoming transfers performed using this handle. The options are not in any way

reset between transfers, so if you want subsequent transfers with dif-

ferent options, you must change them between the transfers. You can optionally reset all options back to internal default with curleasyreset(3). NNOOTTEE:: strings passed to libcurl as 'char *' arguments, will not be copied by the library. Instead you should keep them available until libcurl no longer needs them. Failing to do so will cause very odd behavior or even crashes. libcurl will need them until you call

curleasycleanup(3) or you set the same option again to use a differ-

ent pointer. The handle is the return code from a curleasyinit(3) or curleasyduphandle(3) call. BBEEHHAAVVIIOORR OOPPTTIIOONNSS CURLOPTVERBOSE

Set the parameter to non-zero 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 CUR-

LOPTSTDERR. 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 CURLOPTDEBUGFUNCTION. CURLOPTHEADER

A non-zero parameter tells the library to include the header in

the body output. This is only relevant for protocols that actu-

ally have headers preceding the data (like HTTP). CURLOPTNOPROGRESS

A non-zero parameter tells the library to shut off the built-in

progress meter completely. NNOOTTEE:: future versions of libcurl is likely to not have any

built-in progress meter at all.

CURLOPTNOSIGNAL

Pass a long. If it is non-zero, libcurl will not use any func-

tions 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)

Consider building libcurl with ares support to enable asynchro-

nous DNS lookups. It enables nice timeouts for name resolves without signals. CCAALLLLBBAACCKK OOPPTTIIOONNSS CURLOPTWRITEFUNCTION Function pointer that should match the following prototype: ssiizzeett ffuunnccttiioonn(( vvooiidd **ppttrr,, ssiizzeett ssiizzee,, ssiizzeett nnmmeemmbb,, vvooiidd **ssttrreeaamm));; This function gets called by libcurl as soon as there is data received that needs to be saved. The size of the data pointed to by ptr is size multiplied with nmemb, it will not be zero terminated. Return the number of bytes actually taken care

of. If that amount differs from the amount passed to your func-

tion, it'll signal an error to the library and it will abort the

transfer and return CURLEWRITEERROR.

This function may be called with zero bytes data if the trans-

fered file is empty. Set the stream argument with the CURLOPTWRITEDATA option. NNOOTTEE:: you 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 data that can be passed to the write callback is defined in the curl.h header file: CURLMAXWRITESIZE. CURLOPTWRITEDATA Data pointer to pass to the file write function. Note that if you specify the CURLOPTWRITEFUNCTION, 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. NNOOTTEE:: If you're using libcurl as a win32 DLL, you MUST use the

CURLOPTWRITEFUNCTION if you set this option or you will experi-

ence crashes. This option is also known with the older name CURLOPTFILE, the name CURLOPTWRITEDATA was introduced in 7.9.7. CURLOPTREADFUNCTION Function pointer that should match the following prototype: ssiizzeett ffuunnccttiioonn(( vvooiidd **ppttrr,, ssiizzeett ssiizzee,, ssiizzeett nnmmeemmbb,, vvooiidd **ssttrreeaamm));; This function gets called by libcurl as soon as it needs to read data in order to send it to the peer. The data area pointed at by the pointer ptr may be filled with at most size multiplied with nmemb number of bytes. Your function must return the actual number of bytes that you stored in that memory

area. Returning 0 will signal end-of-file to the library and

cause it to stop the current transfer.

If you stop the current transfer by returning 0 "pre-maturely"

(i.e before the server expected it, like when you've told 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. In libcurl 7.12.1 and later, the read callback may return CURLREADFUNCABORT to stop the current operation at once, with a CURLEABORTEDBYCALLBACK error code from the transfer. CURLOPTREADDATA Data pointer to pass to the file read function. Note that if you specify the CURLOPTREADFUNCTION, this is the pointer you'll get as input. If you don't specify a read callback, this must be a valid FILE *. NNOOTTEE:: If you're using libcurl as a win32 DLL, you MUST use a CURLOPTREADFUNCTION if you set this option. This option is also known with the older name CURLOPTINFILE, the name CURLOPTREADDATA was introduced in 7.9.7. CURLOPTIOCTLFUNCTION

Function pointer that should match the curlioctlcallback pro-

totype found in . 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. (Opion added in

7.12.3) CURLOPTIOCTLDATA Pass a pointer that will be untouched by libcurl and passed as

the 3rd argument in the ioctl callback set with CURLOPTIOCTL-

FUNCTION. (Option added in 7.12.3) CURLOPTPROGRESSFUNCTION Function pointer that should match the curlprogresscallback prototype found in . This function gets called by libcurl instead of its internal equivalent with a frequent interval during data transfer. Unknown/unused argument values will be set to zero (like if you only download data, the upload

size will remain 0). Returning a non-zero value from this call-

back will cause libcurl to abort the transfer and return CURLEABORTEDBYCALLBACK. Also note that CURLOPTNOPROGRESS must be set to FALSE to make this function actually get called. CURLOPTPROGRESSDATA Pass a pointer that will be untouched by libcurl and passed as

the first argument in the progress callback set with CUR-

LOPTPROGRESSFUNCTION. CURLOPTHEADERFUNCTION Function pointer that should match the following prototype: sizet function( void *ptr, sizet size, sizet nmemb, void *stream);. This function gets called by libcurl as soon as there

is received header data that needs to be written down. The head-

ers are guaranteed to be written one-by-one and only complete

lines are written. Parsing headers should be easy enough using this. The size of the data pointed to by ptr is size multiplied with nmemb. The pointer named stream will be the one you passed

to libcurl with the CURLOPTWRITEHEADER option. Return the num-

ber of bytes actually written or return -1 to signal error to

the library (it will cause it to abort the transfer with a

CURLEWRITEERROR return code).

CURLOPTWRITEHEADER Pass a pointer to be used to write the header part of the received data to. If you don't use your own callback to take care of the writing, this must be a valid FILE *. See also the

CURLOPTHEADERFUNCTION option above on how to set a custom get-

all-headers callback.

CURLOPTDEBUGFUNCTION Function pointer that should match the following prototype: int curldebugcallback (CURL *, curlinfotype, char *, sizet, void *); CURLOPTDEBUGFUNCTION replaces the standard debug function used when CURLOPTVERBOSE is in effect. This callback receives debug information, as specified with the ccuurrlliinnffoottyyppee 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 sizet argument. Available curlinfotype values: CURLINFOTEXT The data is informational text. CURLINFOHEADERIN

The data is header (or header-like) data received from

the peer. CURLINFOHEADEROUT

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

peer. CURLINFODATAIN The data is protocol data received from the peer. CURLINFODATAOUT The data is protocol data sent to the peer. CURLOPTDEBUGDATA

Pass a pointer to whatever you want passed in to your CUR-

LOPTDEBUGFUNCTION in the last void * argument. This pointer is not used by libcurl, it is only passed to the callback. CURLOPTSSLCTXFUNCTION Function pointer that should match the following prototype: CCUURRLLccooddee ssssllccttxxffuunn((CCUURRLL **ccuurrll,, vvooiidd **ssssllccttxx,, vvooiidd **ppaarrmm));; This function gets called by libcurl just before the initialization of an SSL connection after having processed all other SSL

related options to give a last chance to an application to mod-

ify the behaviour of openssl's ssl initialization. The sslctx parameter is actually a pointer to an openssl SSLCTX. 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 parm argument with the CUR-

LOPTSSLCTXDATA option. This option was introduced in 7.11.0.

NNOOTTEE:: To use this properly, a non-trivial amount of knowledge of

the openssl libraries is necessary. Using this function allows

for example to use openssl callbacks to add additional valida-

tion code for certificates, and even to change the actual URI of an HTTPS request (example used in the lib509 test case). See

also the example section for a replacement of the key, certifi-

cate and trust file settings. CURLOPTSSLCTXDATA Data pointer to pass to the ssl context callback set by the option CURLOPTSSLCTXFUNCTION, this is the pointer you'll get as third parameter, otherwise NNUULLLL. (Added in 7.11.0) EERRRROORR OOPPTTIIOONNSS

CURLOPTERRORBUFFER

Pass a char * to a buffer that the libcurl may store human read-

able error messages in. This may be more helpful than just the return code from the library. The buffer must be at least

CURLERRORSIZE big.

Use CURLOPTVERBOSE and CURLOPTDEBUGFUNCTION to better debug/trace why errors happen. NNoottee:: if the library does not return an error, the buffer may not have been touched. Do not rely on the contents in those cases. CURLOPTSTDERR Pass a FILE * as parameter. Tell libcurl to use this stream instead of stderr when showing the progress meter and displaying CURLOPTVERBOSE data.

CURLOPTFAILONERROR

A non-zero parameter tells the library to fail silently if the

HTTP code returned is equal to or larger than 300. The default action would be to return the page normally, ignoring that code. NNEETTWWOORRKK OOPPTTIIOONNSS CURLOPTURL The actual URL to deal with. The parameter should be a char * to a zero terminated string. The string must remain present until curl no longer needs it, as it doesn't copy the string. If the given URL lacks the protocol part ("http://" or "ftp://" etc), it will attempt to guess which protocol to use based on the given host name. If the given protocol of the set URL is not

supported, libcurl will return on error (CURLEUNSUPPORTEDPRO-

TOCOL) when you call curleasyperform(3) or curlmultiper-

form(3). Use curlversioninfo(3) for detailed info on which protocols that are supported. NNOOTTEE:: CURLOPTURL is the only option that must be set before curleasyperform(3) is called. CURLOPTPROXY 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 sepa-

rate option CURLOPTPROXYPORT. NNOOTTEE:: when you tell the library to use an HTTP proxy, libcurl

will transparently convert operations to HTTP even if you spec-

ify an FTP URL etc. This may have an impact on what other fea-

tures of the library you can use, such as CURLOPTQUOTE and sim-

ilar FTP specifics that don't work unless you tunnel through the

HTTP proxy. Such tunneling is activated with CURLOPTHTTPPROXY-

TUNNEL. NNOOTTEE22:: libcurl respects the environment variables hhttttpppprrooxxyy, ffttpppprrooxxyy, aallllpprrooxxyy etc, if any of those is set. CURLOPTPROXYPORT Pass a long with this option to set the proxy port to connect to unless it is specified in the proxy string CURLOPTPROXY. CURLOPTPROXYTYPE Pass a long with this option to set type of the proxy. Available options for this are CURLPROXYHTTP and CURLPROXYSOCKS5, with the HTTP one being default. (Added in 7.10) CURLOPTHTTPPROXYTUNNEL

Set the parameter to non-zero to get the library to tunnel all

operations through a given HTTP proxy. Note that 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. CURLOPTINTERFACE Pass a char * as parameter. This set the interface name to use as outgoing network interface. The name can be an interface name, an IP address or a host name. CURLOPTDNSCACHETIMEOUT Pass a long, this sets the timeout in seconds. Name resolves will be kept in memory for this number of seconds. Set to zero

(0) to completely disable caching, or set to -1 to make the

cached entries remain forever. By default, libcurl caches this info for 60 seconds. CURLOPTDNSUSEGLOBALCACHE

Pass a long. If the value is non-zero, 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. WWAARRNNIINNGG:: this option is considered obsolete. Stop using it.

Switch over to using the share interface instead! See CUR-

LOPTSHARE and curlshareinit(3). CURLOPTBUFFERSIZE Pass a long specifying your preferred size 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) CURLOPTPORT 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. CURLOPTTCPNODELAY Pass a long specifying whether the TCPNODELAY option should 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 pur-

pose 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 conges-

tion on the network if overdone.

NAMES and PASSWORDS OPTIONS (Authentication)

CURLOPTNETRC This parameter controls the preference of libcurl between using user names and passwords from your ~/.netrc file, relative to user names and passwords in the URL supplied with CURLOPTURL.

NNoottee:: libcurl uses a user name (and supplied or prompted pass-

word) supplied with CURLOPTUSERPWD in preference to any of the options controlled by this parameter. Pass a long, set to one of the values described below.

CURLNETRCOPTIONAL

The use of your ~/.netrc file is optional, and informa-

tion in the URL is to be preferred. The file will be scanned with the host and user name (to find the password only) or with the host only, to find the first user name and password after that machine, which ever information is not specified in the URL. Undefined values of the option will have this effect. CURLNETRCIGNORED

The library will ignore the file and use only the infor-

mation in the URL. This is the default. CURLNETRCREQUIRED This value tells the library that use of the file is required, to ignore the information in the URL, and to search the file with the host only. Only machine name, user name and password are taken into account (init macros and similar things aren't supported). NNoottee:: 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. CURLOPTNETRCFILE 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 CURLOPTNETRC is set, libcurl will attempt to find the a .netrc file in the current user's home directory. (Added in 7.10.9) CURLOPTUSERPWD

Pass a char * as parameter, which should be [user name]:[pass-

word] to use for the connection. Use CURLOPTHTTPAUTH to decide authentication method.

When using HTTP and CURLOPTFOLLOWLOCATION, libcurl might per-

form several requests to possibly different hosts. libcurl will only send this user and password information to hosts using the initial host name (unless CURLOPTUNRESTRICTEDAUTH 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 acciden-

tal information leakage. CURLOPTPROXYUSERPWD

Pass a char * as parameter, which should be [user name]:[pass-

word] to use for the connection to the HTTP proxy. Use CUR-

LOPTPROXYAUTH to decide authentication method. CURLOPTHTTPAUTH Pass a long as parameter, which is set to a bitmask, to tell libcurl what 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 what authentication methods it supports and then pick the best one you allow it to

use. Note that for some methods, this will induce an extra net-

work round-trip. Set the actual name and password with the CUR-

LOPTUSERPWD option. (Added in 7.10.6) CURLAUTHBASIC HTTP Basic authentication. This is the default choice,

and the only method that is in wide-spread use and sup-

ported virtually everywhere. This is sending the user name and password over the network in plain text, easily captured by others. CURLAUTHDIGEST HTTP Digest authentication. Digest authentication is

defined in RFC2617 and is a more secure way to do authen-

tication over public networks than the regular old-fash-

ioned Basic method. CURLAUTHGSSNEGOTIATE

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 be also used along with another authentication

methods. For more information see IETF draft draft-

brezak-spnego-http-04.txt.

NNOOTTEE that you need to build libcurl with a suitable GSS-

API library for this to work. CURLAUTHNTLM 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. NNOOTTEE that you need to build libcurl with SSL support for this option to work. CURLAUTHANY 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. CURLAUTHANYSAFE 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. CURLOPTPROXYAUTH Pass a long as parameter, which is set to a bitmask, to tell libcurl what 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. Note

that for some methods, this will induce an extra network round-

trip. Set the actual name and password with the CURLOPTPROX-

YUSERPWD option. The bitmask can be constructed by or'ing together the bits listed above for the CURLOPTHTTPAUTH option. As of this writing, only Basic and NTLM work. (Added in 7.10.7) HHTTTTPP OOPPTTIIOONNSS CURLOPTAUTOREFERER

Pass a non-zero parameter to enable this. When enabled, libcurl

will automatically set the Referer: field in requests where it follows a Location: redirect. CURLOPTENCODING

Sets the contents of the Accept-Encoding: header sent in an HTTP

request, and enables decoding of a response when a Content-

Encoding: header is received. Three encodings are supported: identity, which does nothing, deflate which requests the server to compress its response using the zlib algorithm, and gzip

which requests the gzip algorithm. If a zero-length string is

set, then an Accept-Encoding: header containing all supported

encodings is sent. This is a request, not an order; the server may or may not do

it. This option must be set (to any non-NULL value) or else any

unsolicited encoding done by the server is ignored. See the spe-

cial file lib/README.encoding for details. CURLOPTFOLLOWLOCATION

A non-zero parameter tells the library to follow any Location:

header that the server sends as part of an HTTP header.

NNOOTTEE:: 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. CURLOPTMAXREDIRS can be used to limit the number of redirects libcurl will follow. CURLOPTUNRESTRICTEDAUTH

A non-zero parameter tells the library it can continue to send

authentication (user+password) when following locations, even when hostname changed. Note that this is meaningful only when setting CURLOPTFOLLOWLOCATION. CURLOPTMAXREDIRS 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 (CURLETOOMANYREDIRECTS). This option only makes sense if the CURLOPTFOLLOWLOCATION is used at the same time. CURLOPTPUT

A non-zero parameter tells the library to use HTTP PUT to trans-

fer data. The data should be set with CURLOPTREADDATA and CUR-

LOPTINFILESIZE. This option is deprecated and starting with version 7.12.1 you should instead use CURLOPTUPLOAD. CURLOPTPOST

A non-zero parameter tells the library to do a regular HTTP

post. This will also make the library use the a "Content-Type:

application/x-www-form-urlencoded" header. (This is by far the

most commonly used POST method). Use the CURLOPTPOSTFIELDS option to specify what data to post and CURLOPTPOSTFIELDSIZE to set the data size.

Optionally, you can provide data to POST using the CURLOPTREAD-

FUNCTION and CURLOPTREADDATA options but then you must make sure to not set CURLOPTPOSTFIELDS to anything but NULL. When

providing data with a callback, you must transmit it using chun-

ked transfer-encoding or you must set the size of the data with

the CURLOPTPOSTFIELDSIZE option.

You can override the default POST Content-Type: header by set-

ting your own with CURLOPTHTTPHEADER.

Using POST with HTTP 1.1 implies the use of a "Expect: 100-con-

tinue" header. You can disable this header with CURLOPTHTTP-

HEADER 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 CURLOPTHTTPHEADER. With HTTP 1.0 or without chunked transfer, you must specify the size in the request.

NOTE: if you have issued a POST request and want to make a HEAD

or GET instead, you must explictly pick the new request type using CURLOPTNOBODY or CURLOPTHTTPGET or similar. CURLOPTPOSTFIELDS Pass a char * as parameter, which should be the full data to post in an 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. Take note.

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 CURLOPTPOST. Using CURLOPTPOSTFIELDS implies CURLOPTPOST.

Using POST with HTTP 1.1 implies the use of a "Expect: 100-con-

tinue" header. You can disable this header with CURLOPTHTTP-

HEADER as usual.

NNoottee:: to make multipart/formdata posts (aka rfc1867-posts),

check out the CURLOPTHTTPPOST option. CURLOPTPOSTFIELDSIZE 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. CURLOPTPOSTFIELDSIZELARGE Pass a curlofft as parameter. Use this to set the size of the CURLOPTPOSTFIELDS data to prevent libcurl from doing strlen()

on the data to figure out the size. This is the large file ver-

sion of the CURLOPTPOSTFIELDSIZE option. (Added in 7.11.1) CURLOPTHTTPPOST 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 curlhttppost structs as parameter.

. The easiest way to create such a list, is to use curlfor-

madd(3) as documented. The data in this list must remain intact until you close this curl handle again with curleasycleanup(3).

Using POST with HTTP 1.1 implies the use of a "Expect: 100-con-

tinue" header. You can disable this header with CURLOPTHTTP-

HEADER as usual. CURLOPTREFERER 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 CURLOPTHTTPHEADER. CURLOPTUSERAGENT 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 CURLOPTHTTP-

HEADER. CURLOPTHTTPHEADER 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 ssttrruucctt ccuurrllsslliisstt structs properly filled in. Use curlslistappend(3) to create the list and curlslistfreeall(3) to clean up an entire list. If you add a

header that is otherwise generated and used by libcurl inter-

nally, your added one will be used instead. If you add a header with no contents 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. 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 (usually containing a GET or POST) is not a header and cannot be replaced using this option. Only

the lines following the request-line are headers.

Pass a NULL to this to reset back to no custom headers. NNOOTTEE:: The most commonly replaced headers have "shortcuts" in the options CURLOPTCOOKIE, CURLOPTUSERAGENT and CURLOPTREFERER. CURLOPTHTTP200ALIASES 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 curlslist structs, and be properly filled in. Use curlslistappend(3) to create the list and curlslistfreeall(3) to clean up an entire list. NNOOTTEE:: The alias itself is not parsed for any version strings. So if your alias is "MYHTTP/9.9", Libcurl will not treat the server as responding with HTTP version 9.9. Instead Libcurl will use the value set by option CURLOPTHTTPVERSION. CURLOPTCOOKIE 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. Using this option multiple times will only make the latest string override the previously ones. CURLOPTCOOKIEFILE 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 han-

dle, making it understand and parse received cookies and then use matching cookies in future request. CURLOPTCOOKIEJAR Pass a file name as char *, zero terminated. This will make libcurl write all internally known cookies to the specified file when curleasycleanup(3) is called. If no cookies are known, no

file will be created. Specify "-" to instead have the cookies

written to stdout. Using this option also enables cookies for this session, so if you for example follow a location it will make matching cookies get sent accordingly. NNOOTTEE:: If the cookie jar file can't be created or written to (when the curleasycleanup(3) is called), libcurl will not and

cannot report an error for this. Using CURLOPTVERBOSE or CUR-

LOPTDEBUGFUNCTION will get a warning to display, but that is the only visible feedback you get about this possibly lethal situation. CURLOPTCOOKIESESSION

Pass a long set to non-zero to mark this as a new cookie "ses-

sion". 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, indepen-

dent if they are session cookies are not. Session cookies are cookies without expiry date and they are meant to be alive and existing for this "session" only. CURLOPTHTTPGET

Pass a long. If the long is non-zero, this forces the HTTP

request to get back to GET. usable if a POST, HEAD, PUT or a custom request have been used previously using the same curl handle. CURLOPTHTTPVERSION 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. CURLHTTPVERSIONNONE We don't care about what version the library uses. libcurl will use whatever it thinks fit. CURLHTTPVERSION10 Enforce HTTP 1.0 requests. CURLHTTPVERSION11 Enforce HTTP 1.1 requests. FFTTPP OOPPTTIIOONNSS CURLOPTFTPPORT 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 instruc-

tion. 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, an network interface name (under Unix) or just a

'-' letter to let the library use your systems default IP

address. Default FTP operations are passive, and thus won't use PORT. You disable PORT again and go back to using the passive version by setting this option to NULL. CURLOPTQUOTE Pass a pointer to a linked list of FTP commands to pass to the server prior to your ftp request. This will be done before any other FTP commands are issued (even before the CWD command). The linked list should be a fully valid list of to append strings (commands) to the list, and clear the entire list afterwards with curlslistfreeall(3). Disable this operation again by setting a NULL to this option. CURLOPTPOSTQUOTE Pass a pointer to a linked list of FTP commands to pass to the server after your ftp transfer request. The linked list should be a fully valid list of struct curlslist structs properly filled in as described for CURLOPTQUOTE. Disable this operation again by setting a NULL to this option. CURLOPTPREQUOTE 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 curlslist structs properly filled in as described for CURLOPTQUOTE. Disable this operation again by setting a NULL to this option. CURLOPTFTPLISTONLY

A non-zero parameter tells the library to just list the names of

an ftp directory, instead of doing a full directory listing that would include file sizes, dates etc. This causes an FTP NLST command to be sent. Beware that some FTP servers list only files in their response to NLST; they might not include subdirectories and symbolic links. CURLOPTFTPAPPEND

A non-zero parameter tells the library to append to the remote

file instead of overwrite it. This is only useful when uploading to an ftp site. CURLOPTFTPUSEEPRT

Pass a long. If the value is non-zero, it tells curl to use the

EPRT (and LPRT) command when doing active FTP downloads (which is enabled by CURLOPTFTPPORT). Using EPRT means that it will first attempt to use EPRT and then LPRT before using PORT, but if you pass FALSE (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. CURLOPTFTPUSEEPSV

Pass a long. If the value is non-zero, 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 FALSE (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. CURLOPTFTPCREATEMISSINGDIRS

Pass a long. If the value is non-zero, curl will attempt to cre-

ate any remote directory that it fails to CWD into. CWD is the command that changes working directory. (Added in 7.10.7) CURLOPTFTPRESPONSETIMEOUT 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. Note that while curl is waiting for

a response, this value overrides CURLOPTTIMEOUT. It is recom-

mended that if used in conjunction with CURLOPTTIMEOUT, you set

CURLOPTFTPRESPONSETIMEOUT to a value smaller than CUR-

LOPTTIMEOUT. (Added in 7.10.8) CURLOPTFTPSSL Pass a long using one of the values from below, to make libcurl use your desired level of SSL for the ftp transfer. (Added in 7.11.0) CURLFTPSSLNONE Don't attempt to use SSL. CURLFTPSSLTRY Try using SSL, proceed as normal otherwise. CURLFTPSSLCONTROL Require SSL for the control connection or fail with CURLEFTPSSLFAILED. CURLFTPSSLALL Require SSL for all communication or fail with CURLEFTPSSLFAILED. CURLOPTFTPSSLAUTH 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 CURLOPTFTPSSL). (Added in 7.12.2) CURLFTPAUTHDEFAULT Allow libcurl to decide CURLFTPAUTHSSL Try "AUTH SSL" first, and only if that fails try "AUTH TLS" CURLFTPAUTHTLS Try "AUTH TLS" first, and only if that fails try "AUTH SSL" CURLOPTSOURCEURL When set, it enables a FTP third party transfer, using the set URL as source, while CURLOPTURL is the target. CURLOPTSOURCEUSERPWD Set "username:password" to use for the source connection when doing FTP third party transfers. CURLOPTSOURCEQUOTE Exactly like CURLOPTQUOTE, but for the source host. CURLOPTSOURCEPREQUOTE Exactly like CURLOPTPREQUOTE, but for the source host. CURLOPTSOURCEPOSTQUOTE Exactly like CURLOPTPOSTQUOTE, but for the source host. CURLOPTFTPACCOUNT

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) PPRROOTTOOCCOOLL OOPPTTIIOONNSS CURLOPTTRANSFERTEXT

A non-zero parameter tells the library to use ASCII mode for ftp

transfers, instead of the default binary transfer. For LDAP transfers it gets the data in plain text instead of HTML and 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. CURLOPTCRLF Convert Unix newlines to CRLF newlines on transfers. CURLOPTRANGE Pass a char * as parameter, which should contain the specified

range you want. It should be in the format "X-Y", where X or Y

may be left out. HTTP transfers also support several intervals,

separated with commas as in "X-Y,N-M". Using this kind of multi-

ple intervals will cause the HTTP server to send the response document in pieces (using standard MIME separation techniques). Pass a NULL to this option to disable the use of ranges. CURLOPTRESUMEFROM 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). CURLOPTRESUMEFROMLARGE Pass a curlofft as parameter. It contains the offset in number of bytes that you want the transfer to start from. (Added in 7.11.0) CURLOPTCUSTOMREQUEST Pass a pointer to a zero terminated string as parameter. It will be user instead of GET or HEAD when doing an HTTP request, or instead of LIST or NLST when doing an ftp directory listing. This is useful for doing DELETE or other more or less obscure

HTTP requests. Don't do this at will, make sure your server sup-

ports the command first. Restore to the internal default by setting this to NULL. NNOOTTEE:: 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 CURLOPTPOST and CUR-

LOPTPOSTFIELDS to set POST data. Use CURLOPTHTTPHEADER to

replace or extend the set of headers sent by libcurl. Use CUR-

LOPTHTTPVERSION to change HTTP version. CURLOPTFILETIME

Pass a long. If it is a non-zero value, libcurl will attempt to

get the modification date of the remote document in this opera-

tion. This requires that the remote server sends the time or replies to a time querying command. The curleasygetinfo(3) function with the CURLINFOFILETIME argument can be used after a transfer to extract the received time (if any). CURLOPTNOBODY

A non-zero parameter 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 back to GET, you should use CURLOPTHTTPGET. To change

back to POST, you should use CURLOPTPOST. Setting CUR-

LOPTNOBODY to zero has no effect. CURLOPTINFILESIZE 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 CURLOPTINFILE-

SIZELARGE. CURLOPTINFILESIZELARGE 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 curlofft. (Added in 7.11.0) CURLOPTUPLOAD

A non-zero parameter tells the library to prepare for an upload.

The CURLOPTREADDATA and CURLOPTINFILESIZEE or CURLOPTINFILE-

SIZELARGE 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-con-

tinue" header. You can disable this header with CURLOPTHTTP-

HEADER 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 CURLOPTHTTPHEADER. With HTTP 1.0 or without chunked transfer, you must specify the size. CURLOPTMAXFILESIZE 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 CURLEFILESIZEEXCEEDED will be returned. NNOOTTEE:: The file size is not always known prior to download, and

for such files this option has no effect even if the file trans-

fer ends up being larger than this given limit. This concerns both FTP and HTTP transfers. CURLOPTMAXFILESIZELARGE Pass a curlofft 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 CURLEFILESIZEEXCEEDED will be returned. (Added in 7.11.0) NNOOTTEE:: The file size is not always known prior to download, and

for such files this option has no effect even if the file trans-

fer ends up being larger than this given limit. This concerns both FTP and HTTP transfers. CURLOPTTIMECONDITION Pass a long as parameter. This defines how the CURLOPTTIMEVALUE

time value is treated. You can set this parameter to CURLTIME-

CONDIFMODSINCE or CURLTIMECONDIFUNMODSINCE. This feature applies to HTTP and FTP. NNOOTTEE:: 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 have not been met. CURLOPTTIMEVALUE 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 CURLOPTTIMECONDITION. CCOONNNNEECCTTIIOONN OOPPTTIIOONNSS CURLOPTTIMEOUT 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 opera-

tions 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.

NNOOTTEE:: this is not recommended to use in unix multi-threaded pro-

grams, as it uses signals unless CURLOPTNOSIGNAL (see above) is set. CURLOPTLOWSPEEDLIMIT Pass a long as parameter. It contains the transfer speed in

bytes per second that the transfer should be below during CUR-

LOPTLOWSPEEDTIME seconds for the library to consider it too slow and abort. CURLOPTLOWSPEEDTIME Pass a long as parameter. It contains the time in seconds that the transfer should be below the CURLOPTLOWSPEEDLIMIT for the library to consider it too slow and abort. CURLOPTMAXCONNECTS Pass a long. The set number will be the persistent connection

cache size. The set amount will be the maximum amount of simul-

taneously open connections that libcurl may cache. Default is 5, and there isn't much point in changing this value unless you are

perfectly aware of how this work and changes libcurl's behav-

iour. This concerns connection using any of the protocols that support persistent connections.

When reaching the maximum limit, curl uses the CURLOPTCLOSEPOL-

ICY to figure out which of the existing connections to close to prevent the number of open connections to increase. NNOOTTEE:: if you already have performed transfers with this curl handle, setting a smaller MAXCONNECTS than before may cause open connections to get closed unnecessarily. CURLOPTCLOSEPOLICY Pass a long. This option sets what policy libcurl should use

when the connection cache is filled and one of the open connec-

tions has to be closed to make room for a new connection. This

must be one of the CURLCLOSEPOLICY* defines. Use CURLCLOSEPOL-

ICYLEASTRECENTLYUSED to make libcurl close the connection that was least recently used, that connection is also least

likely to be capable of re-use. Use CURLCLOSEPOLICYOLDEST to

make libcurl close the oldest connection, the one that was cre-

ated first among the ones in the connection cache. The other close policies are not support yet. CURLOPTFRESHCONNECT

Pass a long. Set to non-zero 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). CURLOPTFORBIDREUSE

Pass a long. Set to non-zero to make the next transfer explic-

itly close the connection when done. Normally, libcurl keep all connections alive when done with one transfer in case there

comes a succeeding one 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 possibly

later re-use (default behavior).

CURLOPTCONNECTTIMEOUT Pass a long. It should contain the maximum time in seconds that

you allow the connection to the server to take. This only lim-

its the connection phase, once it has connected, this option is of no more use. Set to zero to disable connection timeout (it will then only timeout on the system's internal timeouts). See also the CURLOPTTIMEOUT option.

NNOOTTEE:: this is not recommended to use in unix multi-threaded pro-

grams, as it uses signals unless CURLOPTNOSIGNAL (see above) is set. CURLOPTIPRESOLVE 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: CURLIPRESOLVEWHATEVER Default, resolves addresses to all IP versions that your system allows. CURLIPRESOLVEV4 Resolve to ipv4 addresses. CURLIPRESOLVEV6 Resolve to ipv6 addresses. SSSSLL aanndd SSEECCUURRIITTYY OOPPTTIIOONNSS CURLOPTSSLCERT 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 CURLOPTSSLCERTTYPE. CURLOPTSSLCERTTYPE Pass a pointer to a zero terminated string as parameter. The

string should be the format of your certificate. Supported for-

mats are "PEM" and "DER". (Added in 7.9.3) CURLOPTSSLCERTPASSWD Pass a pointer to a zero terminated string as parameter. It will

be used as the password required to use the CURLOPTSSLCERT cer-

tificate. This option is replaced by CURLOPTSSLKEYPASSWD and should only be used for backward compatibility. You never needed a pass

phrase to load a certificate but you need one to load your pri-

vate key. CURLOPTSSLKEY 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 CURLOPTSSLKEYTYPE. CURLOPTSSLKEYTYPE Pass a pointer to a zero terminated string as parameter. The

string should be the format of your private key. Supported for-

mats are "PEM", "DER" and "ENG". NNOOTTEE:: The format "ENG" enables you to load the private key from

a crypto engine. In this case CURLOPTSSLKEY is used as an iden-

tifier passed to the engine. You have to set the crypto engine with CURLOPTSSLENGINE. "DER" format key file currently does not work because of a bug in OpenSSL. CURLOPTSSLKEYPASSWD Pass a pointer to a zero terminated string as parameter. It will

be used as the password required to use the CURLOPTSSLKEY pri-

vate key. CURLOPTSSLENGINE 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. NNOOTTEE:: If the crypto device cannot be loaded, CURLESSLENGINENOTFOUND is returned. CURLOPTSSLENGINEDEFAULT Sets the actual crypto engine as the default for (asymmetric) crypto operations.

NNOOTTEE:: If the crypto device cannot be set, CURLESSLENGINESET-

FAILED is returned. CURLOPTSSLVERSION Pass a long as parameter. Set what version of SSL to attempt to use, 2 or 3. By default, the SSL library will try to solve this by itself although some servers make this difficult why you at times may have to use this option. CURLOPTSSLVERIFYPEER

Pass a long that is set to a zero value to stop curl from veri-

fying the peer's certificate (7.10 starting setting this option

to non-zero by default). Alternate certificates to verify

against can be specified with the CURLOPTCAINFO option or a certificate directory can be specified with the CURLOPTCAPATH

option. As of 7.10, curl installs a default bundle. CUR-

LOPTSSLVERIFYHOST may also need to be set to 1 or 0 if CUR-

LOPTSSLVERIFYPEER is disabled (it defaults to 2). CURLOPTCAINFO Pass a char * to a zero terminated string naming a file holding one or more certificates to verify the peer with. This only

makes sense when used in combination with the CURLOPTSSLVERI-

FYPEER option. CURLOPTCAPATH Pass a char * to a zero terminated string naming a directory holding multiple CA certificates to verify the peer with. The certificate directory must be prepared using the openssl crehash utility. This only makes sense when used in combination

with the CURLOPTSSLVERIFYPEER option. The CURLOPTCAPATH func-

tion apparently does not work in Windows due to some limitation in openssl. (Added in 7.9.8) CURLOPTRANDOMFILE 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. CURLOPTEGDSOCKET 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. CURLOPTSSLVERIFYHOST Pass a long. Set if we should verify the Common name from the peer certificate in the SSL handshake, set 1 to check existence, 2 to ensure that it matches the provided hostname. This is by default set to 2. (default changed in 7.10) CURLOPTSSLCIPHERLIST 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 sepa-

rators but colons are normally used, , - and + can be used as

operators. 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: http://www.openssl.org/docs/apps/ciphers.html CURLOPTKRB4LEVEL Pass a char * as parameter. Set the krb4 security level, this also enables krb4 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 kerberos4. The kerberos support only works for FTP. OOTTHHEERR OOPPTTIIOONNSS CURLOPTPRIVATE Pass a char * as parameter, pointing to data that should be associated with this curl handle. The pointer can subsequently

be retrieved using curleasygetinfo(3) with the CURLINFOPRI-

VATE option. libcurl itself does nothing with this data. (Added in 7.10.3) CURLOPTSHARE Pass a share handle as a parameter. The share handle must have been created by a previous call to curlshareinit(3). 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, you MMUUSSTT use the locking methods in the share handle. See curlsharesetopt(3) for details. TTEELLNNEETT OOPPTTIIOONNSS

CURLOPTTELNETOPTIONS

Provide a pointer to a curlslist with variables to pass to the telnet negotiations. The variables should be in the format . libcurl supports the options 'TTYPE', 'XDISPLOC' and 'NEWENV'. See the TELNET standard for details. RREETTUURRNN VVAALLUUEE

CURLEOK (zero) means that the option was set properly, non-zero means

an error occurred as defines. See the libcurl-errors(3)

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