NAME
curl_easy_setopt - set options for a curl easy handle
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLoption option,
parameter);
DESCRIPTION
curl_easy_setopt() is used to tell libcurl how to behave. By
using the appropriate options to curl_easy_setopt, you can
change libcurl's behavior. All options are set with the
option followed by a parameter. That parameter can be a
long, a function pointer or an object pointer, all depending
on what the specific option expects. Read this manual care
fully 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.
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.
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 transfers
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 dis
play a lot of verbose information about its operations.
Very useful for libcurl and/or protocol debugging and
understanding.
You hardly ever want this set in production use, you
will almost always want this when you debug/report prob
lems. Another neat option for debugging is the CUR
LOPT_DEBUGFUNCTION.
CURLOPT_HEADER
A non-zero parameter tells the library to include the
header in the body output. This is only relevant for
protocols that actually have headers preceding the data
(like HTTP).
CURLOPT_NOPROGRESS
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 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)
CALLBACK OPTIONS
CURLOPT_WRITEFUNCTION
Function pointer that should match the following proto
type: 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. Return the number of bytes actu
ally 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 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:
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.
This option is also known with the older name CUR
LOPT_FILE, the name CURLOPT_WRITEDATA was introduced in
7.9.7.
CURLOPT_READFUNCTION
Function pointer that should match the following proto
type: 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 multiplied
with nmemb number of bytes. Your function must return
the actual number of bytes that you stored in that mem
ory area. Returning 0 will signal end-of-file to the
library and cause it to stop the current transfer.
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 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
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
requests a password. The function must match this proto
type: int getpass(void *client, char *prompt, 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 CUR
LOPT_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 proto
type: 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 writ
ten. Parsing headers should be easy enough using this.
The size of the data pointed to by ptr is size multi
plied 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 callback
to take care of the writing, this must be a valid FILE
*. See also the CURLOPT_HEADERFUNCTION option below on
how to set a custom get-all-headers callback.
CURLOPT_DEBUGFUNCTION
Function pointer that should match the following proto
type: int curl_debug_callback (CURL *, curl_infotype,
char *, size_t, void *); This function will receive
debug information if CURLOPT_VERBOSE is enabled. The
curl_infotype argument specifies what kind of informa
tion it is. This funtion must return 0.
CURLOPT_DEBUGDATA
Pass a pointer to whatever you want passed in to your
CURLOPT_DEBUGFUNCTION in the last void * argument. This
pointer is not used by libcurl, it is only passed to the
callback.
ERROR OPTIONS
CURLOPT_ERRORBUFFER
Pass a char * to a buffer that the libcurl may store
human readable error messages in. This may be more help
ful 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 better
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 nor
mally, 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 separate option
CURLOPT_PROXYPORT.
NOTE: when you tell the library to use a HTTP proxy,
libcurl will transparently convert operations to HTTP
even if you specify a FTP URL etc. This may have an
impact on what other features of the library you can
use, such as CURLOPT_QUOTE and similar FTP specifics
that don't work unless you tunnel through the HTTP
proxy. Such 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_PROXTYPE
Pass a long with this option to set type of the proxy.
Available options for this are CURLPROXY_HTTP and CURL
PROXY_SOCKS5, with the HTTP one being default. (Added in
7.10)
CURLOPT_HTTPPROXYTUNNEL
Set the parameter to non-zero to get the library to tun
nel 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 sec
onds. 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
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)
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 cor
rect 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
name]:[password] to use for the connection. If the pass
word is left out, you will be prompted for it. CUR
LOPT_PASSWDFUNCTION can be used to set your own prompt
function.
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_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 Location:
headers all the way until no more such headers are
returned. CURLOPT_MAXREDIRS can be used to limit the
number of redirects libcurl will follow.
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_REDI
RECTS). This option only makes sense if the CURLOPT_FOL
LOWLOCATION is used at the same time. (Added in 7.5)
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_POSTFIELDSIZE in
how to set the data size. Starting with libcurl 7.8,
this option is obsolete. Using the CURLOPT_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. This is a normal
application/x-www-form-urlencoded kind, which is the
most commonly used one by HTML forms. See also the CUR
LOPT_POST. Since 7.8, using CURLOPT_POSTFIELDS implies
CURLOPT_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 properly 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).
CURLOPT_REFERER
Pass a pointer to a zero terminated string as parameter.
It will be used to set the Referer: header in the http
request sent to the remote server. This can be used to
fool servers or scripts. You can also set any custom
header with CURLOPT_HTTPHEADER.
CURLOPT_USERAGENT
Pass a pointer to a zero terminated string as parameter.
It will be used to set the User-Agent: header in the
http request sent to the remote server. This can be used
to fool servers or scripts. You can also set any custom
header with CURLOPT_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 otherwise
generated and used by libcurl internally, your added one
will be used instead. If you add a header with no con
tents 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.
NOTE:The most commonly replaced headers have "shortcuts"
in the options CURLOPT_COOKIE, CURLOPT_USERAGENT and
CURLOPT_REFERER.
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 mulitple cookies, you need to set
them all using a single option and thus you need to con
cat them all in one single string. Set multiple cookies
in one string like this: "name1=content1; name2=con
tent2;" etc.
Using this option multiple times will only make the lat
est string override the previously ones.
CURLOPT_COOKIEFILE
Pass a pointer to a zero terminated string as parameter.
It should contain the name of your file holding cookie
data to read. The cookie data may be in Netscape /
Mozilla cookie data format or just regular HTTP-style
headers dumped to a file.
Given an empty or non-existing file, 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 session, 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.
CURLOPT_HTTPGET
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 previously
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 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, an net
work 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.
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_QUOTE. Disable this operation again by setting a
NULL to this option.
CURLOPT_PREQUOTE
Pass a pointer to a linked list of FTP commands to pass
to the server after the transfer type is set. The linked
list should be a fully valid list of struct curl_slist
structs properly filled in as described for CUR
LOPT_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 subdirectories 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 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.
PROTOCOL OPTIONS
CURLOPT_TRANSFERTEXT
A non-zero parameter tells the library to use ASCII mode
for ftp transfers, instead of the default binary trans
fer. 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 differ
ent 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 also
support several intervals, separated with commas as in
"X-Y,N-M". Using this kind of multiple intervals will
cause the HTTP server to send the response document in
pieces (using standard MIME separation techniques).
CURLOPT_RESUME_FROM
Pass a long as parameter. It contains the offset in num
ber of bytes that you want the transfer to start from.
CURLOPT_CUSTOMREQUEST
Pass a pointer to a zero terminated string as parameter.
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 command first.
CURLOPT_FILETIME
Pass a long. If it is a non-zero value, libcurl will
attempt to get the modification date of the remote docu
ment in this operation. This requires that the remote
server sends the time or replies to a time querying com
mand. 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 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.
NOTE: this is not recommended to use in unix multi-
threaded programs, as it uses signals unless CUR
LOPT_NOSIGNAL (see below) 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 con
nection cache size. The set amount will be the maximum
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 con
cerns 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 con
nections 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 unnecessarily.
(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 CURLCLOSEPOLICY_*
defines. Use CURLCLOSEPOLICY_LEAST_RECENTLY_USED to make
libcurl close the connection 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 oldest 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 connection
cache is full before this connection, one of the exist
ing 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 exist
ing 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 sec
onds 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 below) is set.
SSL and SECURITY OPTIONS
CURLOPT_SSLCERT
Pass a pointer to a zero terminated string as parameter.
The string should be the file name of your certificate.
The default format is "PEM" and can be changed with CUR
LOPT_SSLCERTTYPE.
CURLOPT_SSLCERTTYPE
Pass a pointer to a zero terminated string as parameter.
The string should be the format of your certificate.
Supported formats are "PEM" and "DER". (Added in 7.9.3)
CURLOPT_SSLCERTPASSWD
Pass a pointer to a zero terminated string as parameter.
It will be used as the password required to use the CUR
LOPT_SSLCERT certificate. If the password is not sup
plied, you will be prompted for it. CURLOPT_PASSWDFUNC
TION can be used to set your own prompt function.
NOTE:This option is replaced by CURLOPT_SSLKEYPASSWD and
only cept for backward compatibility. You never needed a
pass phrase to load a certificate but you need one to
load your private key.
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 CUR
LOPT_SSLKEYTYPE. (Added in 7.9.3)
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". (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 parameter.
It will be used as the password required to use the CUR
LOPT_SSLKEY private key. If the password is not sup
plied, you will be prompted for it. CURLOPT_PASSWDFUNC
TION 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 parameter.
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 non-zero value to make curl
verify the peer's certificate. The certificate to verify
against must be specified with the CURLOPT_CAINFO option
(Added in 7.4.2) or a certificate directory must be
specified with the CURLOPT_CAPATH option (Added in
7.9.8).
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 combination
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 prepared
using the openssl c_rehash utility. This only makes
sense when used in combination with the CURLOPT_SSL_VER
IFYPEER option. The CAPATH function apparently 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 pro
vided hostname. (Added in 7.8.1)
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 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
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 disable ker
beros4. The kerberos support only works for FTP. (Added
in 7.3)
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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