curl_easy_setopt - set options for a curl easy handle
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLoption option,
parameter);
DESCRIPTION
curl_easy_setopt() is used to tell libcurl how to behave.
By using the appropriate options to curl_easy_setopt, you
can change libcurl's behavior. All options are set with
the option followed by a parameter. That parameter can be
a long, a function pointer or an object pointer, all
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 func-
tion call. A typical application uses many
curl_easy_setopt() calls in the setup phase.
NOTE: 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 curl_easy_cleanup()
or you set the same option again to use a different
pointer.
NOTE2: options set with this function call are valid for
the forthcoming data transfers that are performed when you
invoke curl_easy_perform. The options are not in any way
reset between transfers, so if you want subsequent trans-
fers with different options, you must change them between
the transfers.
The handle is the return code from a curl_easy_init(3) or
curl_easy_duphandle(3) call.
BEHAVIOR OPTIONS
CURLOPT_VERBOSE
Set the parameter to non-zero to get the library to
display a lot of verbose information about its opera-
tions. Very useful for libcurl and/or protocol debug-
ging and understanding.
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
CURLOPT_DEBUGFUNCTION.
CURLOPT_HEADER
A non-zero parameter tells the library to include the
data (like HTTP).
CURLOPT_NOPROGRESS
A non-zero parameter tells the library to shut of the
built-in progress meter completely.
NOTE: future versions of libcurl is likely to not have
any built-in progress meter at all.
CURLOPT_NOSIGNAL
Pass a long. If it is non-zero, libcurl will not use
any functions that install signal handlers or any
functions that cause signals to be sent to the pro-
cess. This option is mainly here to allow multi-
threaded unix applications to still set/use all time-
out options etc, without risking getting signals.
(Added in 7.10)
CALLBACK OPTIONS
CURLOPT_WRITEFUNCTION
Function pointer that should match the following pro-
totype: size_t function( void *ptr, size_t size,
size_t nmemb, void *stream); This function gets called
by libcurl as soon as there is data reveiced 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 function, it'll signal an error to the library
and it will abort the transfer and return
CURLE_WRITE_ERROR.
Set the stream argument with the CURLOPT_FILE option.
NOTE: you will be passed as much data as possible in
all invokes, but you cannot possibly make any assump-
tions. 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:
CURL_MAX_WRITE_SIZE.
CURLOPT_WRITEDATA
Data pointer to pass to the file write function. Note
that if you specify the CURLOPT_WRITEFUNCTION, 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.
NOTE: If you're using libcurl as a win32 DLL, you MUST
use the CURLOPT_WRITEFUNCTION if you set this option
or you will experience crashes.
LOPT_FILE, the name CURLOPT_WRITEDATA was introduced
in 7.9.7.
CURLOPT_READFUNCTION
Function pointer that should match the following pro-
totype: size_t function( void *ptr, size_t size,
size_t nmemb, void *stream); 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 multi-
plied 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 trans-
fer.
CURLOPT_READDATA
Data pointer to pass to the file read function. Note
that if you specify the CURLOPT_READFUNCTION, this is
the pointer you'll get as input. If you don't specify
a read callback, this must be a valid FILE *.
NOTE: If you're using libcurl as a win32 DLL, you MUST
use a CURLOPT_READFUNCTION if you set this option.
This option is also known with the older name CUR-
LOPT_INFILE, the name CURLOPT_READDATA was introduced
in 7.9.7.
CURLOPT_PROGRESSFUNCTION
Function pointer that should match the
curl_progress_callback prototype found in
<curl/curl.h>. This function gets called by libcurl
instead of its internal equivalent with a frequent
interval during data transfer. Unknown/unused argu-
ment values will be set to zero (like if you only
download data, the upload size will remain 0). Return-
ing a non-zero value from this callback will cause
libcurl to abort the transfer and return
CURLE_ABORTED_BY_CALLBACK.
Also note that CURLOPT_NOPROGRESS must be set to FALSE
to make this function actually get called.
CURLOPT_PROGRESSDATA
Pass a pointer that will be untouched by libcurl and
passed as the first argument in the progress callback
set with CURLOPT_PROGRESSFUNCTION.
CURLOPT_PASSWDFUNCTION
Pass a pointer to a curl_passwd_callback function that
will be called instead of the internal one if libcurl
char* buffer, int buflen );. If set to NULL, it sets
back the function to the internal default one. If the
function returns a non-zero value, it will abort the
operation and an error (CURLE_BAD_PASSWORD_ENTERED)
will be returned. client is a generic pointer, see
CURLOPT_PASSWDDATA. prompt is a zero-terminated
string that is text that prefixes the input request.
buffer is a pointer to data where the entered password
should be stored and buflen is the maximum number of
bytes that may be written in the buffer. (Added in
7.4.2)
CURLOPT_PASSWDDATA
Pass a void * to whatever data you want. The passed
pointer will be the first argument sent to the
specifed CURLOPT_PASSWDFUNCTION function. (Added in
7.4.2)
CURLOPT_HEADERFUNCTION
Function pointer that should match the following pro-
totype: size_t function( void *ptr, size_t size,
size_t nmemb, void *stream);. This function gets
called by libcurl as soon as there is received header
data that needs to be written down. The headers 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
CURLOPT_WRITEHEADER option. Return the number of
bytes actually written or return -1 to signal error to
the library (it will cause it to abort the transfer
with a CURLE_WRITE_ERROR return code). (Added in
7.7.2)
CURLOPT_WRITEHEADER
Pass a pointer to be used to write the header part of
the received data to. If you don't use your own call-
back to take care of the writing, this must be a valid
FILE *. See also the CURLOPT_HEADERFUNCTION option
above on how to set a custom get-all-headers callback.
CURLOPT_DEBUGFUNCTION
Function pointer that should match the following pro-
totype: int curl_debug_callback (CURL *, curl_info-
type, char *, size_t, void *); This function will
receive debug information if CURLOPT_VERBOSE is
enabled. The curl_infotype argument specifies what
kind of information it is. This funtion must return 0.
NOTE: the data pointed to by the char * passed to this
function WILL NOT be zero terminated, but will be
Pass a pointer to whatever you want passed in to your
CURLOPT_DEBUGFUNCTION in the last void * argument.
This pointer is not used by libcurl, it is only passed
to the callback.
ERROR OPTIONS
CURLOPT_ERRORBUFFER
Pass a char * to a buffer that the libcurl may store
human readable error messages in. This may be more
helpful than just the return code from the library.
The buffer must be at least CURL_ERROR_SIZE big.
Use CURLOPT_VERBOSE and CURLOPT_DEBUGFUNCTION to bet-
ter debug/trace why errors happen.
Note: if the library does not return an error, the
buffer may not have been touched. Do not rely on the
contents in those cases.
CURLOPT_STDERR
Pass a FILE * as parameter. This is the stream to use
instead of stderr internally when reporting errors.
CURLOPT_FAILONERROR
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.
NETWORK OPTIONS
CURLOPT_URL
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.
NOTE: this option is (the only one) required to be set
before curl_easy_perform(3) is called.
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 sepa-
rate option CURLOPT_PROXYPORT.
NOTE: when you tell the library to use a HTTP proxy,
impact on what other features of the library you can
use, such as CURLOPT_QUOTE and similar FTP specifics
that don't work unless you tunnel through the HTTP
proxy. Such tunneling is activated with CURLOPT_HTTP-
PROXYTUNNEL.
NOTE2: libcurl respects the environment variables
http_proxy, ftp_proxy, all_proxy etc, if any of those
is set.
CURLOPT_PROXYPORT
Pass a long with this option to set the proxy port to
connect to unless it is specified in the proxy string
CURLOPT_PROXY.
CURLOPT_PROXYTYPE
Pass a long with this option to set type of the proxy.
Available options for this are CURLPROXY_HTTP and
CURLPROXY_SOCKS5, with the HTTP one being default.
(Added in 7.10)
CURLOPT_HTTPPROXYTUNNEL
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.
(Added in 7.3)
CURLOPT_INTERFACE
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. (Added in 7.3)
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 (0) to completely disable
caching, or set to -1 to make the cached entries
remain forever. By default, libcurl caches info for 60
seconds. (Added in 7.9.3)
CURLOPT_DNS_USE_GLOBAL_CACHE
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 varible. (Added
in 7.9.3)
CURLOPT_BUFFERSIZE
Pass a long specifying your prefered size for the
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)
NAMES and PASSWORDS OPTIONS
CURLOPT_NETRC
This parameter controls the preference of libcurl
between using user names and passwords from your
~/.netrc file, relative to user names and passwords in
the URL supplied with CURLOPT_URL.
Note: libcurl uses a user name (and supplied or
prompted password) supplied with CURLOPT_USERPWD in
preference to any of the options controlled by this
parameter.
Pass a long, set to one of the values described below.
CURL_NETRC_OPTIONAL
The use of your ~/.netrc file is optional, and
information in the URL is to be preferred. The
file will be scanned 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.
CURL_NETRC_IGNORED
The library will ignore the file and use only the
information in the URL.
This is the default.
CURL_NETRC_REQUIRED
This value tells the library that use of the file
is required, to ignore the information in the
URL, and to search the file with the host only.
Only machine name, user name and password are taken into
account
(init macros and similar things aren't supported).
Note: libcurl does not verify that the file has the
correct properties set (as the standard Unix ftp
client does). It should only be readable by user.
CURLOPT_USERPWD
Pass a char * as parameter, which should be [user
prompted for it while using a colon with no password
will make libcurl use an empty password. CURLOPT_PASS-
WDFUNCTION can be used to set your own prompt func-
tion.
When using HTTP and CURLOPT_FOLLOWLOCATION, 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, so
if libcurl follows locations to other hosts it will
not send the user and password to those. This is
enforced to prevent accidental information leakage.
CURLOPT_PROXYUSERPWD
Pass a char * as parameter, which should be [user
name]:[password] to use for the connection to the HTTP
proxy. If the password is left out, you will be
prompted for it. CURLOPT_PASSWDFUNCTION can be used to
set your own prompt function.
HTTP OPTIONS
CURLOPT_ENCODING
Two encodings are supported dentity, which does noth-
ing, and deflate to request the server to compress its
reponse using the zlib algorithm. This is not an
order, the server may or may not do it. See the spe-
cial file lib/README.encoding for details.
CURLOPT_FOLLOWLOCATION
A non-zero parameter tells the library to follow any
Location: header that the server sends as part of a
HTTP header.
NOTE: this means that the library will re-send the
same request on the new location and follow new Loca-
tion: headers all the way until no more such headers
are returned. CURLOPT_MAXREDIRS can be used to limit
the number of redirects libcurl will follow.
CURLOPT_UNRESTRICTED_AUTH
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 CURLOPT_FOLLOWLOCA-
TION.
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
(CURLE_TOO_MANY_REDIRECTS). This option only makes
CURLOPT_PUT
A non-zero parameter tells the library to use HTTP PUT
to transfer data. The data should be set with CUR-
LOPT_READDATA and CURLOPT_INFILESIZE.
CURLOPT_POST
A non-zero parameter tells the library to do a regular
HTTP post. This is a normal application/x-www-form-
urlencoded kind, which is the most commonly used one
by HTML forms. See the CURLOPT_POSTFIELDS option for
how to specify the data to post and CURLOPT_POSTFIELD-
SIZE in how to set the data size. Starting with
libcurl 7.8, this option is obsolete. Using the CUR-
LOPT_POSTFIELDS option will imply this option.
CURLOPT_POSTFIELDS
Pass a char * as parameter, which should be the full
data to post in a HTTP post operation. You need to
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-urlen-
coded 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 CUR-
LOPT_POST. Using CURLOPT_POSTFIELDS implies CUR-
LOPT_POST.
Note: to make multipart/formdata posts (aka
rfc1867-posts), check out the CURLOPT_HTTPPOST option.
CURLOPT_POSTFIELDSIZE
If you want to post data to the server without letting
libcurl do a strlen() to measure the data size, this
option must be used. When this option is used you can
post fully binary data, which otherwise is likely to
fail. If this size is set to zero, the library will
use strlen() to get the size. (Added in libcurl 7.2)
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 HTTP
post structs as parameter. The linked list should be
a fully valid list of 'struct HttpPost' structs prop-
erly filled in. The best and most elegant way to do
this, is to use curl_formadd(3) as documented. The
data in this list must remain intact until you close
this curl handle again with curl_easy_cleanup(3).
Pass a pointer to a zero terminated string as parame-
ter. It will be used to set the Referer: header in the
http request sent to the remote server. This can be
used to fool servers or scripts. You can also set any
custom header with CURLOPT_HTTPHEADER.
CURLOPT_USERAGENT
Pass a pointer to a zero terminated string as parame-
ter. It will be used to set the User-Agent: header in
the http request sent to the remote server. This can
be used to fool servers or scripts. You can also set
any custom header with CURLOPT_HTTPHEADER.
CURLOPT_HTTPHEADER
Pass a pointer to a linked list of HTTP headers to
pass to the server in your HTTP request. The linked
list should be a fully valid list of struct curl_slist
structs properly filled in. Use curl_slist_append(3)
to create the list and curl_slist_free_all(3) to clean
up an entire list. If you add a header that is other-
wise generated and used by libcurl internally, 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.
NOTE:The most commonly replaced headers have "short-
cuts" in the options CURLOPT_COOKIE, CURLOPT_USERAGENT
and CURLOPT_REFERER.
CURLOPT_HTTP200ALIASES
Pass a pointer to a linked list of aliases to be
treated as valid HTTP 200 responses. Some servers
respond with a custom header response line. For exam-
ple, IceCast servers respond with "ICY 200 OK". By
including this string in your list of aliases, the
response will be treated as a valid HTTP header line
such as "HTTP/1.0 200 OK". (Added in 7.10.3)
The linked list should be a fully valid list of struct
curl_slist structs, and be properly filled in. Use
curl_slist_append(3) to create the list and
curl_slist_free_all(3) to clean up an entire list.
NOTE:The alias itself is not parsed for any version
strings. So if your alias is "MYHTTP/9.9", Libcurl
by option CURLOPT_HTTP_VERSION.
CURLOPT_COOKIE
Pass a pointer to a zero terminated string as parame-
ter. It will be used to set a cookie in the http
request. The format of the string should be NAME=CON-
TENTS, where NAME is the cookie name and CONTENTS is
what the cookie should contain.
If you need to set mulitple cookies, you need to set
them all using a single option and thus you need to
concat 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.
CURLOPT_COOKIEFILE
Pass a pointer to a zero terminated string as parame-
ter. 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, this option will
enable cookies for this curl handle, making it under-
stand and parse received cookies and then use matching
cookies in future request.
CURLOPT_COOKIEJAR
Pass a file name as char *, zero terminated. This will
make libcurl write all internally known cookies to the
specified file when curl_easy_cleanup(3) is called. If
no cookies are known, no file will be created. Specify
"-" to instead have the cookies written to stdout.
Using this option also enables cookies for this ses-
sion, so if you for example follow a location it will
make matching cookies get sent accordingly. (Added in
7.9)
CURLOPT_TIMECONDITION
Pass a long as parameter. This defines how the CUR-
LOPT_TIMEVALUE time value is treated. You can set this
parameter to TIMECOND_IFMODSINCE or TIMECOND_IFUN-
MODSINCE. This is a HTTP-only feature. (TBD)
CURLOPT_TIMEVALUE
Pass a long as parameter. This should be the time in
seconds since 1 jan 1970, and the time will be used in
a condition as specified with CURLOPT_TIMECONDITION.
Pass a long. If the long is non-zero, this forces the
HTTP request to get back to GET. Only really usable if
POST, PUT or a custom request have been used previ-
ously using the same curl handle. (Added in 7.8.1)
CURLOPT_HTTP_VERSION
Pass a long, set to one of the values described below.
They force libcurl to use the specific HTTP versions.
This is not sensible to do unless you have a good rea-
son.
CURL_HTTP_VERSION_NONE
We don't care about what version the library
uses. libcurl will use whatever it thinks fit.
CURL_HTTP_VERSION_1_0
Enforce HTTP 1.0 requests.
CURL_HTTP_VERSION_1_1
Enforce HTTP 1.1 requests.
FTP OPTIONS
CURLOPT_FTPPORT
Pass a pointer to a zero terminated string as parame-
ter. 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, 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 pas-
sive version by setting this option to NULL.
CURLOPT_QUOTE
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
curl_slist_free_all(3). Disable this operation again
by setting a NULL to this option.
CURLOPT_POSTQUOTE
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
curl_slist structs properly filled in as described for
CURLOPT_PREQUOTE
Pass a pointer to a linked list of FTP commands to
pass to the server after the transfer type is set. The
linked list should be a fully valid list of struct
curl_slist structs properly filled in as described for
CURLOPT_QUOTE. Disable this operation again by setting
a NULL to this option.
CURLOPT_FTPLISTONLY
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 subdirecto-
ries and symbolic links.
CURLOPT_FTPAPPEND
A non-zero parameter tells the library to append to
the remote file instead of overwrite it. This is only
useful when uploading to a ftp site.
CURLOPT_FTP_USE_EPSV
Pass a long. If the value is non-zero, it tells curl
to use the EPSV command when doing passive FTP down-
loads (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.
PROTOCOL OPTIONS
CURLOPT_TRANSFERTEXT
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.
CURLOPT_CRLF
Convert Unix newlines to CRLF newlines on transfers.
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
will cause the HTTP server to send the response docu-
ment in pieces (using standard MIME separation tech-
niques).
CURLOPT_RESUME_FROM
Pass a long as parameter. It contains the offset in
number of bytes that you want the transfer to start
from.
CURLOPT_CUSTOMREQUEST
Pass a pointer to a zero terminated string as parame-
ter. It will be user instead of GET or HEAD when doing
the HTTP request. This is useful for doing DELETE or
other more or less obscure HTTP requests. Don't do
this at will, make sure your server supports the com-
mand first.
CURLOPT_FILETIME
Pass a long. If it is a non-zero value, libcurl will
attempt to get the modification date of the remote
document in this operation. This requires that the
remote server sends the time or replies to a time
querying command. The curl_easy_getinfo(3) function
with the CURLINFO_FILETIME argument can be used after
a transfer to extract the received time (if any).
(Added in 7.5)
CURLOPT_NOBODY
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.
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.
CURLOPT_UPLOAD
A non-zero parameter tells the library to prepare for
an upload. The CURLOPT_READDATA and CURLOPT_INFILESIZE
are also interesting for uploads.
CONNECTION OPTIONS
CURLOPT_TIMEOUT
Pass a long as parameter containing the maximum time
in seconds that you allow the libcurl transfer opera-
tion to take. Normally, name lookups can take a con-
siderable 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.
threaded programs, as it uses signals unless CUR-
LOPT_NOSIGNAL (see above) is set.
CURLOPT_LOW_SPEED_LIMIT
Pass a long as parameter. It contains the transfer
speed in bytes per second that the transfer should be
below during CURLOPT_LOW_SPEED_TIME seconds for the
library to consider it too slow and abort.
CURLOPT_LOW_SPEED_TIME
Pass a long as parameter. It contains the time in sec-
onds that the transfer should be below the CUR-
LOPT_LOW_SPEED_LIMIT for the library to consider it
too slow and abort.
CURLOPT_MAXCONNECTS
Pass a long. The set number will be the persistent
connection cache size. The set amount will be the max-
imum amount of simultaneously 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
behaviour. This concerns connection using any of the
protocols that support persistent connections.
When reaching the maximum limit, curl uses the CUR-
LOPT_CLOSEPOLICY to figure out which of the existing
connections to close to prevent the number of open
connections to increase.
NOTE: if you already have performed transfers with
this curl handle, setting a smaller MAXCONNECTS than
before may cause open connections to get closed unnec-
essarily. (Added in 7.7)
CURLOPT_CLOSEPOLICY
Pass a long. This option sets what policy libcurl
should use when the connection cache is filled and one
of the open connections has to be closed to make room
for a new connection. This must be one of the CURL-
CLOSEPOLICY_* defines. Use CURLCLOSEPOL-
ICY_LEAST_RECENTLY_USED to make libcurl close the con-
nection that was least recently used, that connection
is also least likely to be capable of re-use. Use
CURLCLOSEPOLICY_OLDEST to make libcurl close the old-
est connection, the one that was created first among
the ones in the connection cache. The other close
policies are not support yet. (Added in 7.7)
CURLOPT_FRESH_CONNECT
Pass a long. Set to non-zero to make the next transfer
use a new (fresh) connection by force. If the connec-
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). (Added in
7.7)
CURLOPT_FORBID_REUSE
Pass a long. Set to non-zero to make the next transfer
explicitly 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). (Added in 7.7)
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 disable connection timeout (it will then only
timeout on the system's internal timeouts). See also
the CURLOPT_TIMEOUT option.
NOTE: this is not recommended to use in unix multi-
threaded programs, as it uses signals unless CUR-
LOPT_NOSIGNAL (see above) is set.
SSL and SECURITY OPTIONS
CURLOPT_SSLCERT
Pass a pointer to a zero terminated string as parame-
ter. The string should be the file name of your cer-
tificate. The default format is "PEM" and can be
changed with CURLOPT_SSLCERTTYPE.
CURLOPT_SSLCERTTYPE
Pass a pointer to a zero terminated string as parame-
ter. The string should be the format of your certifi-
cate. Supported formats are "PEM" and "DER". (Added
in 7.9.3)
CURLOPT_SSLCERTPASSWD
Pass a pointer to a zero terminated string as parame-
ter. It will be used as the password required to use
the CURLOPT_SSLCERT certificate. If the password is
not supplied, you will be prompted for it. CUR-
LOPT_PASSWDFUNCTION can be used to set your own prompt
function.
NOTE:This option is replaced by CURLOPT_SSLKEYPASSWD
need one to load your private key.
CURLOPT_SSLKEY
Pass a pointer to a zero terminated string as parame-
ter. The string should be the file name of your pri-
vate key. The default format is "PEM" and can be
changed with CURLOPT_SSLKEYTYPE. (Added in 7.9.3)
CURLOPT_SSLKEYTYPE
Pass a pointer to a zero terminated string as parame-
ter. The string should be the format of your private
key. Supported formats are "PEM", "DER" and "ENG".
(Added in 7.9.3)
NOTE:The format "ENG" enables you to load the private
key from a crypto engine. in this case CURLOPT_SSLKEY
is used as an identifier passed to the engine. You
have to set the crypto engine with CURLOPT_SSL_ENGINE.
CURLOPT_SSLKEYPASSWD
Pass a pointer to a zero terminated string as parame-
ter. It will be used as the password required to use
the CURLOPT_SSLKEY private key. If the password is not
supplied, you will be prompted for it. CURLOPT_PASSWD-
FUNCTION can be used to set your own prompt function.
(Added in 7.9.3)
CURLOPT_SSL_ENGINE
Pass a pointer to a zero terminated string as parame-
ter. It will be used as the identifier for the crypto
engine you want to use for your private key. (Added in
7.9.3)
NOTE:If the crypto device cannot be loaded,
CURLE_SSL_ENGINE_NOTFOUND is returned.
CURLOPT_SSL_ENGINEDEFAULT
Sets the actual crypto engine as the default for (asy-
metric) crypto operations. (Added in 7.9.3)
NOTE:If the crypto device cannot be set,
CURLE_SSL_ENGINE_SETFAILED is returned.
CURLOPT_SSLVERSION
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.
CURLOPT_SSL_VERIFYPEER
Pass a long that is set to a zero value to stop curl
certificates to verify against can be specified with
the CURLOPT_CAINFO option (Added in 7.4.2) or a cer-
tificate directory can be specified with the CUR-
LOPT_CAPATH option (Added in 7.9.8). As of 7.10, curl
installs a default bundle. CURLOPT_SSL_VERIFYHOST may
also need to be set to 1 or 0 if CURLOPT_SSL_VERI-
FYPEER is disabled (it defaults to 2).
CURLOPT_CAINFO
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 combina-
tion with the CURLOPT_SSL_VERIFYPEER option. (Added in
7.4.2)
CURLOPT_CAPATH
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 pre-
pared using the openssl c_rehash utility. This only
makes sense when used in combination with the CUR-
LOPT_SSL_VERIFYPEER option. The CAPATH function appar-
ently does not work in Windows due to some limitation
in openssl. (Added in 7.9.8)
CURLOPT_RANDOM_FILE
Pass a char * to a zero terminated file name. The file
will be used to read from to seed the random engine
for SSL. The more random the specified file is, the
more secure the SSL connection will become.
CURLOPT_EGDSOCKET
Pass a char * to the zero terminated path name to the
Entropy Gathering Daemon socket. It will be used to
seed the random engine for SSL.
CURLOPT_SSL_VERIFYHOST
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. (Added
in 7.8.1, default changed in 7.10)
CURLOPT_SSL_CIPHER_LIST
Pass a char *, pointing to a zero terminated string
holding the list of ciphers to use for the SSL connec-
tion. The list must be syntactly 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. Valid examples of cipher lists include
'RC4-SHA', 'SHA1+DES', 'TLSv1' and 'DEFAULT'. The
URL: http://www.openssl.org/docs/apps/ciphers.html
CURLOPT_KRB4LEVEL
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 dis-
able kerberos4. The kerberos support only works for
FTP. (Added in 7.3)
OTHER OPTIONS
CURLOPT_PRIVATE
Pass a char * as parameter, pointing to data that
should be associated with the curl handle. The
pointer can be subsequently retrieved using the
CURLINFO_PRIVATE options to curl_easy_getinfo. (Added
in 7.10.3)
RETURN VALUE
CURLE_OK (zero) means that the option was set properly,
non-zero means an error occurred as <curl/curl.h> defines.
See the libcurl-errors.3 man page for the full list with
descriptions.
SEE ALSO
curl_easy_init(3), curl_easy_cleanup(3),
BUGS
If you find any bugs, or just have questions, subscribe to
one of the mailing lists and post. We won't bite.
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