curl_setopt

Parameters

handle

A cURL handle returned by curl_init().

option

The CURLOPT_XXX option to set.

value

The value to be set on option.

value should be a bool for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_AUTOREFERER	true to automatically set the Referer: field in requests where it follows a Location: redirect.
CURLOPT_COOKIESESSION	true to mark this as a new cookie "session". It will force libcurl to ignore all cookies it is about to load that are "session cookies" from the previous session. By default, libcurl always stores and loads all cookies, independent if they are session cookies or not. Session cookies are cookies without expiry date and they are meant to be alive and existing for this "session" only.
CURLOPT_CERTINFO	true to output SSL certification information to STDERR on secure transfers.	Added in cURL 7.19.1. Requires CURLOPT_VERBOSE to be on to have an effect.
CURLOPT_CONNECT_ONLY	true tells the library to perform all the required proxy authentication and connection setup, but no data transfer. This option is implemented for HTTP, SMTP and POP3.	Added in 7.15.2.
CURLOPT_CRLF	true to convert Unix newlines to CRLF newlines on transfers.
CURLOPT_DISALLOW_USERNAME_IN_URL	true to not allow URLs that include a username. Usernames are allowed by default (0).	Added in cURL 7.61.0. Available since PHP 7.3.0.
CURLOPT_DNS_SHUFFLE_ADDRESSES	true to shuffle the order of all returned addresses so that they will be used in a random order, when a name is resolved and more than one IP address is returned. This may cause IPv4 to be used before IPv6 or vice versa.	Added in cURL 7.60.0. Available since PHP 7.3.0.
CURLOPT_HAPROXYPROTOCOL	true to send an HAProxy PROXY protocol v1 header at the start of the connection. The default action is not to send this header.	Added in cURL 7.60.0. Available since PHP 7.3.0.
CURLOPT_SSH_COMPRESSION	true to enable built-in SSH compression. This is a request, not an order; the server may or may not do it.	Added in cURL 7.56.0. Available since PHP 7.3.0.
CURLOPT_DNS_USE_GLOBAL_CACHE	true to use a global DNS cache. This option is not thread-safe. It is conditionally enabled by default if PHP is built for non-threaded use (CLI, FCGI, Apache2-Prefork, etc.).
CURLOPT_FAILONERROR	true to fail verbosely if the HTTP code returned is greater than or equal to 400. The default behavior is to return the page normally, ignoring the code.
CURLOPT_SSL_FALSESTART	true to enable TLS false start.	Added in cURL 7.42.0. Available since PHP 7.0.7.
CURLOPT_FILETIME	true to attempt to retrieve the modification date of the remote document. This value can be retrieved using the CURLINFO_FILETIME option with curl_getinfo().
CURLOPT_FOLLOWLOCATION	true to follow any "Location: " header that the server sends as part of the HTTP header. See also CURLOPT_MAXREDIRS.
CURLOPT_FORBID_REUSE	true to force the connection to explicitly close when it has finished processing, and not be pooled for reuse.
CURLOPT_FRESH_CONNECT	true to force the use of a new connection instead of a cached one.
CURLOPT_FTP_USE_EPRT	true to use EPRT (and LPRT) when doing active FTP downloads. Use false to disable EPRT and LPRT and use PORT only.
CURLOPT_FTP_USE_EPSV	true to first try an EPSV command for FTP transfers before reverting back to PASV. Set to false to disable EPSV.
CURLOPT_FTP_CREATE_MISSING_DIRS	true to create missing directories when an FTP operation encounters a path that currently doesn't exist.
CURLOPT_FTPAPPEND	true to append to the remote file instead of overwriting it.
CURLOPT_TCP_NODELAY	true to disable TCP's Nagle algorithm, which tries to minimize the number of small packets on the network.	Available for versions compiled with libcurl 7.11.2 or greater.
CURLOPT_FTPASCII	An alias of CURLOPT_TRANSFERTEXT. Use that instead.
CURLOPT_FTPLISTONLY	true to only list the names of an FTP directory.
CURLOPT_HEADER	true to include the header in the output.
CURLINFO_HEADER_OUT	true to track the handle's request string.	The CURLINFO_ prefix is intentional.
CURLOPT_HTTP09_ALLOWED	Whether to allow HTTP/0.9 responses. Defaults to false as of libcurl 7.66.0; formerly it defaulted to true.	Available since PHP 7.3.15 and 7.4.3, respectively, if built against libcurl >= 7.64.0
CURLOPT_HTTPGET	true to reset the HTTP request method to GET. Since GET is the default, this is only necessary if the request method has been changed.
CURLOPT_HTTPPROXYTUNNEL	true to tunnel through a given HTTP proxy.
CURLOPT_HTTP_CONTENT_DECODING	false to get the raw HTTP response body.	Available if built against libcurl >= 7.16.2.
CURLOPT_KEEP_SENDING_ON_ERROR	true to keep sending the request body if the HTTP code returned is equal to or larger than 300. The default action would be to stop sending and close the stream or connection. Suitable for manual NTLM authentication. Most applications do not need this option.	Available as of PHP 7.3.0 if built against libcurl >= 7.51.0.
CURLOPT_MUTE	true to be completely silent with regards to the cURL functions.	Removed in cURL 7.15.5 (You can use CURLOPT_RETURNTRANSFER instead)
CURLOPT_NETRC	true to scan the ~/.netrc file to find a username and password for the remote site that a connection is being established with.
CURLOPT_NOBODY	true to exclude the body from the output. Request method is then set to HEAD. Changing this to false does not change it to GET.
CURLOPT_NOPROGRESS	true to disable the progress meter for cURL transfers. Note: PHP automatically sets this option to true, this should only be changed for debugging purposes.
CURLOPT_NOSIGNAL	true to ignore any cURL function that causes a signal to be sent to the PHP process. This is turned on by default in multi-threaded SAPIs so timeout options can still be used.	Added in cURL 7.10.
CURLOPT_PATH_AS_IS	true to not handle dot dot sequences.	Added in cURL 7.42.0. Available since PHP 7.0.7.
CURLOPT_PIPEWAIT	true to wait for pipelining/multiplexing.	Added in cURL 7.43.0. Available since PHP 7.0.7.
CURLOPT_POST	true to do a regular HTTP POST. This POST is the normal application/x-www-form-urlencoded kind, most commonly used by HTML forms.
CURLOPT_PUT	true to HTTP PUT a file. The file to PUT must be set with CURLOPT_INFILE and CURLOPT_INFILESIZE.
CURLOPT_RETURNTRANSFER	true to return the transfer as a string of the return value of curl_exec() instead of outputting it directly.
CURLOPT_SASL_IR	true to enable sending the initial response in the first packet.	Added in cURL 7.31.10. Available since PHP 7.0.7.
CURLOPT_SSL_ENABLE_ALPN	false to disable ALPN in the SSL handshake (if the SSL backend libcurl is built to use supports it), which can be used to negotiate http2.	Added in cURL 7.36.0. Available since PHP 7.0.7.
CURLOPT_SSL_ENABLE_NPN	false to disable NPN in the SSL handshake (if the SSL backend libcurl is built to use supports it), which can be used to negotiate http2.	Added in cURL 7.36.0. Available since PHP 7.0.7.
CURLOPT_SSL_VERIFYPEER	false to stop cURL from verifying the peer's certificate. Alternate certificates to verify against can be specified with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option.	true by default as of cURL 7.10. Default bundle installed as of cURL 7.10.
CURLOPT_SSL_VERIFYSTATUS	true to verify the certificate's status.	Added in cURL 7.41.0. Available since PHP 7.0.7.
CURLOPT_PROXY_SSL_VERIFYPEER	false to stop cURL from verifying the peer's certificate. Alternate certificates to verify against can be specified with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option. When set to false, the peer certificate verification succeeds regardless.	true by default. Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_SAFE_UPLOAD	Always true, what disables support for the @ prefix for uploading files in CURLOPT_POSTFIELDS, which means that values starting with @ can be safely passed as fields. CURLFile may be used for uploads instead.
CURLOPT_SUPPRESS_CONNECT_HEADERS	true to suppress proxy CONNECT response headers from the user callback functions CURLOPT_HEADERFUNCTION and CURLOPT_WRITEFUNCTION, when CURLOPT_HTTPPROXYTUNNEL is used and a CONNECT request is made.	Added in cURL 7.54.0. Available since PHP 7.3.0.
CURLOPT_TCP_FASTOPEN	true to enable TCP Fast Open.	Added in cURL 7.49.0. Available since PHP 7.0.7.
CURLOPT_TFTP_NO_OPTIONS	true to not send TFTP options requests.	Added in cURL 7.48.0. Available since PHP 7.0.7.
CURLOPT_TRANSFERTEXT	true to use ASCII mode for FTP transfers. For LDAP, it retrieves data in plain text instead of HTML. On Windows systems, it will not set STDOUT to binary mode.
CURLOPT_UNRESTRICTED_AUTH	true to keep sending the username and password when following locations (using CURLOPT_FOLLOWLOCATION), even when the hostname has changed.
CURLOPT_UPLOAD	true to prepare for an upload.
CURLOPT_VERBOSE	true to output verbose information. Writes output to STDERR, or the file specified using CURLOPT_STDERR.

value should be an int for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_BUFFERSIZE	The size of the buffer to use for each read. There is no guarantee this request will be fulfilled, however.	Added in cURL 7.10.
CURLOPT_CONNECTTIMEOUT	The number of seconds to wait while trying to connect. Use 0 to wait indefinitely.
CURLOPT_CONNECTTIMEOUT_MS	The number of milliseconds to wait while trying to connect. Use 0 to wait indefinitely. If libcurl is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second.	Added in cURL 7.16.2.
CURLOPT_DNS_CACHE_TIMEOUT	The number of seconds to keep DNS entries in memory. This option is set to 120 (2 minutes) by default.
CURLOPT_EXPECT_100_TIMEOUT_MS	The timeout for Expect: 100-continue responses in milliseconds. Defaults to 1000 milliseconds.	Added in cURL 7.36.0. Available since PHP 7.0.7.
CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS	Head start for ipv6 for the happy eyeballs algorithm. Happy eyeballs attempts to connect to both IPv4 and IPv6 addresses for dual-stack hosts, preferring IPv6 first for timeout milliseconds. Defaults to CURL_HET_DEFAULT, which is currently 200 milliseconds.	Added in cURL 7.59.0. Available since PHP 7.3.0.
CURLOPT_FTPSSLAUTH	The FTP authentication method (when is activated): CURLFTPAUTH_SSL (try SSL first), CURLFTPAUTH_TLS (try TLS first), or CURLFTPAUTH_DEFAULT (let cURL decide).	Added in cURL 7.12.2.
CURLOPT_HEADEROPT	How to deal with headers. One of the following constants: CURLHEADER_UNIFIED The headers specified in CURLOPT_HTTPHEADER will be used in requests both to servers and proxies. With this option enabled, CURLOPT_PROXYHEADER will not have any effect. CURLHEADER_SEPARATE Makes CURLOPT_HTTPHEADER headers only get sent to a server and not to a proxy. Proxy headers must be set with CURLOPT_PROXYHEADER to get used. Note that if a non-CONNECT request is sent to a proxy, libcurl will send both server headers and proxy headers. When doing CONNECT, libcurl will send CURLOPT_PROXYHEADER headers only to the proxy and then CURLOPT_HTTPHEADER headers only to the server. Defaults to CURLHEADER_SEPARATE as of cURL 7.42.1, and CURLHEADER_UNIFIED before.	Added in cURL 7.37.0. Available since PHP 7.0.7.
CURLOPT_HTTP_VERSION	CURL_HTTP_VERSION_NONE (default, lets CURL decide which version to use), CURL_HTTP_VERSION_1_0 (forces HTTP/1.0), CURL_HTTP_VERSION_1_1 (forces HTTP/1.1), CURL_HTTP_VERSION_2_0 (attempts HTTP 2), CURL_HTTP_VERSION_2 (alias of CURL_HTTP_VERSION_2_0), CURL_HTTP_VERSION_2TLS (attempts HTTP 2 over TLS (HTTPS) only) or CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE (issues non-TLS HTTP requests using HTTP/2 without HTTP/1.1 Upgrade).
CURLOPT_HTTPAUTH	The HTTP authentication method(s) to use. The options are: CURLAUTH_BASIC, CURLAUTH_DIGEST, CURLAUTH_GSSNEGOTIATE, CURLAUTH_NTLM, CURLAUTH_AWS_SIGV4, CURLAUTH_ANY, and CURLAUTH_ANYSAFE. The bitwise | (or) operator can be used to combine more than one method. If this is done, cURL will poll the server to see what methods it supports and pick the best one. CURLAUTH_ANY sets all bits. cURL will automatically select the one it finds most secure. CURLAUTH_ANYSAFE sets all bits except CURLAUTH_BASIC. cURL will automatically select the one it finds most secure.
CURLOPT_INFILESIZE	The expected size, in bytes, of the file when uploading a file to a remote site. Note that using this option will not stop libcurl from sending more data, as exactly what is sent depends on CURLOPT_READFUNCTION.
CURLOPT_LOW_SPEED_LIMIT	The transfer speed, in bytes per second, that the transfer should be below during the count of CURLOPT_LOW_SPEED_TIME seconds before PHP considers the transfer too slow and aborts.
CURLOPT_LOW_SPEED_TIME	The number of seconds the transfer speed should be below CURLOPT_LOW_SPEED_LIMIT before PHP considers the transfer too slow and aborts.
CURLOPT_MAIL_RCPT_ALLLOWFAILS	Allow RCPT TO command to fail for some recipients.	When sending data to multiple recipients, by default cURL will abort SMTP conversation if at least one of the recipients causes RCPT TO command to return an error. This option tells cURL to ignore errors and proceed with the remaining valid recipients. If all recipients trigger RCPT TO failures and this flag is set, cURL will abort the SMTP conversation and return the error received from the last RCPT TO command.
CURLOPT_MAXAGE_CONN	The maximum idle time allowed for an existing connection to be considered for reuse. Default maximum age is set to 118 seconds.
CURLOPT_MAXFILESIZE_LARGE	The maximum file size in bytes allowed to download. If the file requested is found larger than this value, the transfer will not start and CURLE_FILESIZE_EXCEEDED will be returned. The file size is not always known prior to download, and for such files this option has no effect even if the file transfer ends up being larger than this given limit.
CURLOPT_MAXLIFETIME_CONN	The maximum time in seconds, since the creation of the connection, that is allowed for an existing connection to have for it to be considered for reuse. If a connection is found in the cache that is older than this value, it will instead be closed once any in-progress transfers are complete. Default is 0 seconds, meaning the option is disabled and all connections are eligible for reuse.
CURLOPT_MAXCONNECTS	The maximum amount of persistent connections that are allowed. When the limit is reached, the oldest one in the cache is closed to prevent increasing the number of open connections.
CURLOPT_MAXREDIRS	The maximum amount of HTTP redirections to follow. Use this option alongside CURLOPT_FOLLOWLOCATION. Default value of 20 is set to prevent infinite redirects. Setting to -1 allows inifinite redirects, and 0 refuses all redirects.
CURLOPT_PORT	An alternative port number to connect to.
CURLOPT_POSTREDIR	A bitmask of 1 (301 Moved Permanently), 2 (302 Found) and 4 (303 See Other) if the HTTP POST method should be maintained when CURLOPT_FOLLOWLOCATION is set and a specific type of redirect occurs.	Added in cURL 7.19.1.
CURLOPT_PROTOCOLS	Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols libcurl may use in the transfer. This allows you to have a libcurl built to support a wide range of protocols but still limit specific transfers to only be allowed to use a subset of them. By default libcurl will accept all protocols it supports. See also CURLOPT_REDIR_PROTOCOLS. Valid protocol options are: CURLPROTO_HTTP, CURLPROTO_HTTPS, CURLPROTO_FTP, CURLPROTO_FTPS, CURLPROTO_SCP, CURLPROTO_SFTP, CURLPROTO_TELNET, CURLPROTO_LDAP, CURLPROTO_LDAPS, CURLPROTO_DICT, CURLPROTO_FILE, CURLPROTO_TFTP, CURLPROTO_MQTT, CURLPROTO_ALL	Added in cURL 7.19.4.
CURLOPT_PROXYAUTH	The HTTP authentication method(s) to use for the proxy connection. Use the same bitmasks as described in CURLOPT_HTTPAUTH. For proxy authentication, only CURLAUTH_BASIC and CURLAUTH_NTLM are currently supported.	Added in cURL 7.10.7.
CURLOPT_PROXYPORT	The port number of the proxy to connect to. This port number can also be set in CURLOPT_PROXY.
CURLOPT_PROXYTYPE	Either CURLPROXY_HTTP (default), CURLPROXY_SOCKS4, CURLPROXY_SOCKS5, CURLPROXY_SOCKS4A or CURLPROXY_SOCKS5_HOSTNAME.	Added in cURL 7.10.
CURLOPT_REDIR_PROTOCOLS	Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols libcurl may use in a transfer that it follows to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. This allows you to limit specific transfers to only be allowed to use a subset of protocols in redirections. By default libcurl will allow all protocols except for FILE and SCP. This is a difference compared to pre-7.19.4 versions which unconditionally would follow to all protocols supported. See also CURLOPT_PROTOCOLS for protocol constant values.	Added in cURL 7.19.4.
CURLOPT_RESUME_FROM	The offset, in bytes, to resume a transfer from.
CURLOPT_SOCKS5_AUTH	The SOCKS5 authentication method(s) to use. The options are: CURLAUTH_BASIC, CURLAUTH_GSSAPI, CURLAUTH_NONE. The bitwise | (or) operator can be used to combine more than one method. If this is done, cURL will poll the server to see what methods it supports and pick the best one. CURLAUTH_BASIC allows username/password authentication. CURLAUTH_GSSAPI allows GSS-API authentication. CURLAUTH_NONE allows no authentication. Defaults to CURLAUTH_BASIC|CURLAUTH_GSSAPI. Set the actual username and password with the CURLOPT_PROXYUSERPWD option.	Available as of 7.3.0 and curl >= 7.55.0.
CURLOPT_SSL_OPTIONS	Set SSL behavior options, which is a bitmask of the following constants: CURLSSLOPT_ALLOW_BEAST Do not attempt to use any workarounds for a security flaw in the SSL3 and TLS1.0 protocols. CURLSSLOPT_NO_REVOKE Disable certificate revocation checks for those SSL backends where such behavior is present. CURLSSLOPT_AUTO_CLIENT_CERT Automatically locate and use a client certificate for authentication, when requested by the server. This option is only supported for Schannel (the native Windows SSL library). CURLSSLOPT_NATIVE_CA Use the operating system's native CA store for certificate verification. Works only on Windows when built to use OpenSSL. Note: This option is experimental and behavior is subject to change. CURLSSLOPT_NO_PARTIALCHAIN Do not accept "partial" certificate chains, which cURL otherwise does by default. This option is only supported for OpenSSL and will fail the certificate verification if the chain ends with an intermediate certificate and not with a root certificate. CURLSSLOPT_REVOKE_BEST_EFFORT Ignore certificate revocation checks in case of missing or offline distribution points for those SSL backends where such behavior is present. This option is only supported for Schannel (the native Windows SSL library). Note: If combined with CURLSSLOPT_NO_REVOKE, the latter takes precedence.	Added in cURL 7.25.0. Available since PHP 7.0.7.
CURLOPT_SSL_VERIFYHOST	2 to verify that a Common Name field or a Subject Alternate Name field in the SSL peer certificate matches the provided hostname. 0 to not check the names. 1 should not be used. In production environments the value of this option should be kept at 2 (default value).	Support for value 1 removed in cURL 7.28.1.
CURLOPT_SSLVERSION	One of CURL_SSLVERSION_DEFAULT, CURL_SSLVERSION_TLSv1, CURL_SSLVERSION_SSLv2, CURL_SSLVERSION_SSLv3, CURL_SSLVERSION_TLSv1_0, CURL_SSLVERSION_TLSv1_1, CURL_SSLVERSION_TLSv1_2, CURL_SSLVERSION_TLSv1_3 . The maximum TLS version can be set by using one of the CURL_SSLVERSION_MAX_* constants. It is also possible to bitwise OR one of the CURL_SSLVERSION_* constants with one of the CURL_SSLVERSION_MAX_*. CURL_SSLVERSION_MAX_DEFAULT (the maximum version supported by the library), CURL_SSLVERSION_MAX_TLSv1_0, CURL_SSLVERSION_MAX_TLSv1_1, CURL_SSLVERSION_MAX_TLSv1_2, CURL_SSLVERSION_MAX_TLSv1_3 . Warning It is better to not set this option and leave the defaults. As setting this to CURL_SSLVERSION_SSLv2 or CURL_SSLVERSION_SSLv3 is very dangerous, given the known vulnerabilities in SSLv2 and SSLv3.
CURLOPT_PROXY_SSL_OPTIONS	Set proxy SSL behavior options, which is a bitmask of the following constants: CURLSSLOPT_ALLOW_BEAST Do not attempt to use any workarounds for a security flaw in the SSL3 and TLS1.0 protocols. CURLSSLOPT_NO_REVOKE Disable certificate revocation checks for those SSL backends where such behavior is present. (curl >= 7.44.0) CURLSSLOPT_NO_PARTIALCHAIN Do not accept "partial" certificate chains, which it otherwise does by default. (curl >= 7.68.0)	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_SSL_VERIFYHOST	Set to 2 to verify in the HTTPS proxy's certificate name fields against the proxy name. When set to 0 the connection succeeds regardless of the names used in the certificate. Use that ability with caution! 1 treated as a debug option in curl 7.28.0 and earlier. From curl 7.28.1 to 7.65.3 CURLE_BAD_FUNCTION_ARGUMENT is returned. From curl 7.66.0 onwards 1 and 2 is treated as the same value. In production environments the value of this option should be kept at 2 (default value).	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_SSLVERSION	One of CURL_SSLVERSION_DEFAULT, CURL_SSLVERSION_TLSv1, CURL_SSLVERSION_TLSv1_0, CURL_SSLVERSION_TLSv1_1, CURL_SSLVERSION_TLSv1_2, CURL_SSLVERSION_TLSv1_3, CURL_SSLVERSION_MAX_DEFAULT, CURL_SSLVERSION_MAX_TLSv1_0, CURL_SSLVERSION_MAX_TLSv1_1, CURL_SSLVERSION_MAX_TLSv1_2, CURL_SSLVERSION_MAX_TLSv1_3, CURL_SSLVERSION_SSLv3 . Warning It is better to not set this option and leave the default CURL_SSLVERSION_DEFAULT which will attempt to figure out the remote SSL protocol version.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_STREAM_WEIGHT	Set the numerical stream weight (a number between 1 and 256).	Added in cURL 7.46.0. Available since PHP 7.0.7.
CURLOPT_TCP_KEEPALIVE	If set to 1, TCP keepalive probes will be sent. The delay and frequency of these probes can be controlled by the CURLOPT_TCP_KEEPIDLE and CURLOPT_TCP_KEEPINTVL options, provided the operating system supports them. If set to 0 (default) keepalive probes are disabled.	Added in cURL 7.25.0.
CURLOPT_TCP_KEEPIDLE	Sets the delay, in seconds, that the operating system will wait while the connection is idle before sending keepalive probes, if CURLOPT_TCP_KEEPALIVE is enabled. Not all operating systems support this option. The default is 60.	Added in cURL 7.25.0.
CURLOPT_TCP_KEEPINTVL	Sets the interval, in seconds, that the operating system will wait between sending keepalive probes, if CURLOPT_TCP_KEEPALIVE is enabled. Not all operating systems support this option. The default is 60.	Added in cURL 7.25.0.
CURLOPT_TIMECONDITION	How CURLOPT_TIMEVALUE is treated. Use CURL_TIMECOND_IFMODSINCE to return the page only if it has been modified since the time specified in CURLOPT_TIMEVALUE. If it hasn't been modified, a "304 Not Modified" header will be returned assuming CURLOPT_HEADER is true. Use CURL_TIMECOND_IFUNMODSINCE for the reverse effect. Use CURL_TIMECOND_NONE to ignore CURLOPT_TIMEVALUE and always return the page. CURL_TIMECOND_NONE is the default.	Before cURL 7.46.0 the default was CURL_TIMECOND_IFMODSINCE.
CURLOPT_TIMEOUT	The maximum number of seconds to allow cURL functions to execute.
CURLOPT_TIMEOUT_MS	The maximum number of milliseconds to allow cURL functions to execute. If libcurl is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second.	Added in cURL 7.16.2.
CURLOPT_TIMEVALUE	The time in seconds since January 1st, 1970. The time will be used by CURLOPT_TIMECONDITION.
CURLOPT_TIMEVALUE_LARGE	The time in seconds since January 1st, 1970. The time will be used by CURLOPT_TIMECONDITION. Defaults to zero. The difference between this option and CURLOPT_TIMEVALUE is the type of the argument. On systems where 'long' is only 32 bit wide, this option has to be used to set dates beyond the year 2038.	Added in cURL 7.59.0. Available since PHP 7.3.0.
CURLOPT_UPKEEP_INTERVAL_MS	Some protocols have "connection upkeep" mechanisms. These mechanisms usually send some traffic on existing connections in order to keep them alive. This option defines the connection upkeep interval. Currently, the only protocol with a connection upkeep mechanism is HTTP/2. When the connection upkeep interval is exceeded, an HTTP/2 PING frame is sent on the connection. Default is 60 seconds.
CURLOPT_UPLOAD_BUFFERSIZE	Preferred buffer size in bytes for the cURL upload buffer. The upload buffer size by default is 64 kilobytes. The maximum buffer size allowed to be set is 2 megabytes. The minimum buffer size allowed to be set is 16 kilobytes.
CURLOPT_MAX_RECV_SPEED_LARGE	If a download exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed.	Added in cURL 7.15.5.
CURLOPT_MAX_SEND_SPEED_LARGE	If an upload exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed.	Added in cURL 7.15.5.
CURLOPT_SSH_AUTH_TYPES	A bitmask consisting of one or more of CURLSSH_AUTH_PUBLICKEY, CURLSSH_AUTH_PASSWORD, CURLSSH_AUTH_HOST, CURLSSH_AUTH_KEYBOARD. Set to CURLSSH_AUTH_ANY to let libcurl pick one.	Added in cURL 7.16.1.
CURLOPT_IPRESOLVE	Allows an application to select what kind of IP addresses to use when resolving host names. This is only interesting when using host names that resolve addresses using more than one version of IP, possible values are CURL_IPRESOLVE_WHATEVER, CURL_IPRESOLVE_V4, CURL_IPRESOLVE_V6, by default CURL_IPRESOLVE_WHATEVER.	Added in cURL 7.10.8.
CURLOPT_FTP_FILEMETHOD	Tell curl which method to use to reach a file on a FTP(S) server. Possible values are CURLFTPMETHOD_DEFAULT, CURLFTPMETHOD_MULTICWD, CURLFTPMETHOD_NOCWD, and CURLFTPMETHOD_SINGLECWD.	Added in cURL 7.15.1.

value should be a string for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_ABSTRACT_UNIX_SOCKET	Enables the use of an abstract Unix domain socket instead of establishing a TCP connection to a host and sets the path to the given string. This option shares the same semantics as CURLOPT_UNIX_SOCKET_PATH. These two options share the same storage and therefore only one of them can be set per handle.	Available since PHP 7.3.0 and cURL 7.53.0
CURLOPT_ALTSVC	Pass the filename for cURL to use as the Alt-Svc cache file to read existing cache contents from and possibly also write it back to a after a transfer, unless CURLALTSVC_READONLYFILE is set via CURLOPT_ALTSVC_CTRL.
CURLOPT_ALTSVC_CTRL	Populate the bitmask with the correct set of features to instruct cURL how to handle Alt-Svc for the transfers using this handle. cURL only accepts Alt-Svc headers over HTTPS. It will also only complete a request to an alternative origin if that origin is properly hosted over HTTPS. Setting any bit will enable the alt-svc engine. The options are: CURLALTSVC_H1, CURLALTSVC_H2, CURLALTSVC_H3, and CURLALTSVC_READONLYFILE.
CURLOPT_AWS_SIGV4	Provides AWS V4 signature authentication on HTTP(S) header. This option overrides any other authentication types that have been set in CURLOPT_HTTPAUTH. This method cannot be combined with other authentication types.
CURLOPT_CAINFO	The name of a file holding one or more certificates to verify the peer with. This only makes sense when used in combination with CURLOPT_SSL_VERIFYPEER.	Might require an absolute path.
CURLOPT_CAINFO_BLOB	The name of a PEM file holding one or more certificates to verify the peer with. This option overrides CURLOPT_CAINFO.	Available as of PHP 8.2.0 and cURL 7.77.0
CURLOPT_CAPATH	A directory that holds multiple CA certificates. Use this option alongside CURLOPT_SSL_VERIFYPEER.
CURLOPT_COOKIE	The contents of the "Cookie: " header to be used in the HTTP request. Note that multiple cookies are separated with a semicolon followed by a space (e.g., "fruit=apple; colour=red")
CURLOPT_COOKIEFILE	The name of the file containing the cookie data. The cookie file can be in Netscape format, or just plain HTTP-style headers dumped into a file. If the name is an empty string, no cookies are loaded, but cookie handling is still enabled.
CURLOPT_COOKIEJAR	The name of a file to save all internal cookies to when the handle's destructor is called. Warning As of PHP 8.0.0, curl_close() is a no-op and does not destroy the handle. If cookies need to be written prior to the handle being automatically destroyed, call unset() on the handle.
CURLOPT_COOKIELIST	A cookie string (i.e. a single line in Netscape/Mozilla format, or a regular HTTP-style Set-Cookie header) adds that single cookie to the internal cookie store. "ALL" erases all cookies held in memory. "SESS" erases all session cookies held in memory. "FLUSH" writes all known cookies to the file specified by CURLOPT_COOKIEJAR. "RELOAD" loads all cookies from the files specified by CURLOPT_COOKIEFILE.	Available since cURL 7.14.1.
CURLOPT_CUSTOMREQUEST	A custom request method to use instead of "GET" or "HEAD" when doing a HTTP request. This is useful for doing "DELETE" or other, more obscure HTTP requests. Valid values are things like "GET", "POST", "CONNECT" and so on; i.e. Do not enter a whole HTTP request line here. For instance, entering "GET /index.html HTTP/1.0\r\n\r\n" would be incorrect. Note: Don't do this without making sure the server supports the custom request method first.
CURLOPT_DEFAULT_PROTOCOL	The default protocol to use if the URL is missing a scheme name.	Added in cURL 7.45.0. Available since PHP 7.0.7.
CURLOPT_DNS_INTERFACE	Set the name of the network interface that the DNS resolver should bind to. This must be an interface name (not an address).	Added in cURL 7.33.0. Available since PHP 7.0.7.
CURLOPT_DNS_LOCAL_IP4	Set the local IPv4 address that the resolver should bind to. The argument should contain a single numerical IPv4 address as a string.	Added in cURL 7.33.0. Available since PHP 7.0.7.
CURLOPT_DNS_LOCAL_IP6	Set the local IPv6 address that the resolver should bind to. The argument should contain a single numerical IPv6 address as a string.	Added in cURL 7.33.0. Available since PHP 7.0.7.
CURLOPT_EGDSOCKET	Like CURLOPT_RANDOM_FILE, except a filename to an Entropy Gathering Daemon socket.
CURLOPT_ENCODING	The contents of the "Accept-Encoding: " header. This enables decoding of the response. Supported encodings are "identity", "deflate", and "gzip". If an empty string, "", is set, a header containing all supported encoding types is sent.	Added in cURL 7.10.
CURLOPT_FTPPORT	The value which 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 hostname, a network interface name (under Unix), or just a plain '-' to use the systems default IP address.
CURLOPT_HSTS	HSTS (HTTP Strict Transport Security) cache file name.
CURLOPT_HSTS_CTRL	Controls HSTS (HTTP Strict Transport Security) behavior. Populate the bitmask with the correct set of features to instruct cURL how to handle HSTS for the transfers using this handle. CURLHSTS_ENABLE enables the in-memory HSTS cache. If the HSTS cache file is defined, set CURLHSTS_READONLYFILE to make the file read-only.
CURLOPT_INTERFACE	The name of the outgoing network interface to use. This can be an interface name, an IP address or a host name.
CURLOPT_KEYPASSWD	The password required to use the CURLOPT_SSLKEY or CURLOPT_SSH_PRIVATE_KEYFILE private key.	Added in cURL 7.16.1.
CURLOPT_KRB4LEVEL	The KRB4 (Kerberos 4) security level. Any of the following values (in order from least to most powerful) are valid: "clear", "safe", "confidential", "private".. If the string does not match one of these, "private" is used. Setting this option to null will disable KRB4 security. Currently KRB4 security only works with FTP transactions.
CURLOPT_LOGIN_OPTIONS	Can be used to set protocol specific login options, such as the preferred authentication mechanism via "AUTH=NTLM" or "AUTH=*", and should be used in conjunction with the CURLOPT_USERNAME option.	Added in cURL 7.34.0. Available since PHP 7.0.7.
CURLOPT_PINNEDPUBLICKEY	Set the pinned public key. The string can be the file name of your pinned public key. The file format expected is "PEM" or "DER". The string can also be any number of base64 encoded sha256 hashes preceded by "sha256//" and separated by ";".	Added in cURL 7.39.0. Available since PHP 7.0.7.
CURLOPT_POSTFIELDS	The full data to post in a HTTP "POST" operation. This parameter can either be passed as a urlencoded string like 'para1=val1&para2=val2&...' or as an array with the field name as key and field data as value. If value is an array, the Content-Type header will be set to multipart/form-data. Files can be sent using CURLFile or CURLStringFile, in which case value must be an array.
CURLOPT_PRIVATE	Any data that should be associated with this cURL handle. This data can subsequently be retrieved with the CURLINFO_PRIVATE option of curl_getinfo(). cURL does nothing with this data. When using a cURL multi handle, this private data is typically a unique key to identify a standard cURL handle.	Added in cURL 7.10.3.
CURLOPT_PRE_PROXY	Set a string holding the host name or dotted numerical IP address to be used as the preproxy that curl connects to before it connects to the HTTP(S) proxy specified in the CURLOPT_PROXY option for the upcoming request. The preproxy can only be a SOCKS proxy and it should be prefixed with [scheme]:// to specify which kind of socks is used. A numerical IPv6 address must be written within [brackets]. Setting the preproxy to an empty string explicitly disables the use of a preproxy. To specify port number in this string, append :[port] to the end of the host name. The proxy's port number may optionally be specified with the separate option CURLOPT_PROXYPORT. Defaults to using port 1080 for proxies if a port is not specified.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY	The HTTP proxy to tunnel requests through.
CURLOPT_PROXY_SERVICE_NAME	The proxy authentication service name.	Added in cURL 7.43.0 for HTTP proxies, and in cURL 7.49.0 for SOCKS5 proxies. Available since PHP 7.0.7.
CURLOPT_PROXY_CAINFO	The path to proxy Certificate Authority (CA) bundle. Set the path as a string naming a file holding one or more certificates to verify the HTTPS proxy with. This option is for connecting to an HTTPS proxy, not an HTTPS server. Defaults set to the system path where libcurl's cacert bundle is assumed to be stored.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_CAINFO_BLOB	The name of a PEM file holding one or more certificates to verify the HTTPS proxy with. This option is for connecting to an HTTPS proxy, not an HTTPS server. Defaults set to the system path where libcurl's cacert bundle is assumed to be stored.	Available as of PHP 8.2.0 and libcurl >= cURL 7.77.0.
CURLOPT_PROXY_CAPATH	The directory holding multiple CA certificates to verify the HTTPS proxy with.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_CRLFILE	Set the file name with the concatenation of CRL (Certificate Revocation List) in PEM format to use in the certificate validation that occurs during the SSL exchange.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_KEYPASSWD	Set the string be used as the password required to use the CURLOPT_PROXY_SSLKEY private key. You never needed a passphrase to load a certificate but you need one to load your private key. This option is for connecting to an HTTPS proxy, not an HTTPS server.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_PINNEDPUBLICKEY	Set the pinned public key for HTTPS proxy. The string can be the file name of your pinned public key. The file format expected is "PEM" or "DER". The string can also be any number of base64 encoded sha256 hashes preceded by "sha256//" and separated by ";"	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_SSLCERT	The file name of your client certificate used to connect to the HTTPS proxy. The default format is "P12" on Secure Transport and "PEM" on other engines, and can be changed with CURLOPT_PROXY_SSLCERTTYPE. With NSS or Secure Transport, this can also be the nickname of the certificate you wish to authenticate with as it is named in the security database. If you want to use a file from the current directory, please precede it with "./" prefix, in order to avoid confusion with a nickname.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_SSLCERTTYPE	The format of your client certificate used when connecting to an HTTPS proxy. Supported formats are "PEM" and "DER", except with Secure Transport. OpenSSL (versions 0.9.3 and later) and Secure Transport (on iOS 5 or later, or OS X 10.7 or later) also support "P12" for PKCS#12-encoded files. Defaults to "PEM".	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_SSL_CIPHER_LIST	The list of ciphers to use for the connection to the HTTPS proxy. The list must be syntactically correct, it consists of one or more cipher strings separated by colons. Commas or spaces are also acceptable separators but colons are normally used, !, - and + can be used as operators.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_TLS13_CIPHERS	The list of cipher suites to use for the TLS 1.3 connection to a proxy. The list must be syntactically correct, it consists of one or more cipher suite strings separated by colons. This option is currently used only when curl is built to use OpenSSL 1.1.1 or later. If you are using a different SSL backend you can try setting TLS 1.3 cipher suites by using the CURLOPT_PROXY_SSL_CIPHER_LIST option.	Available since PHP 7.3.0 and libcurl >= cURL 7.61.0. Available when built with OpenSSL >= 1.1.1.
CURLOPT_PROXY_SSLKEY	The file name of your private key used for connecting to the HTTPS proxy. The default format is "PEM" and can be changed with CURLOPT_PROXY_SSLKEYTYPE. (iOS and Mac OS X only) This option is ignored if curl was built against Secure Transport.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0. Available if built TLS enabled.
CURLOPT_PROXY_SSLKEYTYPE	The format of your private key. Supported formats are "PEM", "DER" and "ENG".	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_TLSAUTH_PASSWORD	The password to use for the TLS authentication method specified with the CURLOPT_PROXY_TLSAUTH_TYPE option. Requires that the CURLOPT_PROXY_TLSAUTH_USERNAME option to also be set.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_TLSAUTH_TYPE	The method of the TLS authentication used for the HTTPS connection. Supported method is "SRP". Note: Secure Remote Password (SRP) authentication for TLS provides mutual authentication if both sides have a shared secret. To use TLS-SRP, you must also set the CURLOPT_PROXY_TLSAUTH_USERNAME and CURLOPT_PROXY_TLSAUTH_PASSWORD options.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXY_TLSAUTH_USERNAME	The username to use for the HTTPS proxy TLS authentication method specified with the CURLOPT_PROXY_TLSAUTH_TYPE option. Requires that the CURLOPT_PROXY_TLSAUTH_PASSWORD option to also be set.	Available since PHP 7.3.0 and libcurl >= cURL 7.52.0.
CURLOPT_PROXYUSERPWD	A username and password formatted as "[username]:[password]" to use for the connection to the proxy.
CURLOPT_RANDOM_FILE	A filename to be used to seed the random number generator for SSL.
CURLOPT_RANGE	Range(s) of data to retrieve in the format "X-Y" where X or Y are optional. HTTP transfers also support several intervals, separated with commas in the format "X-Y,N-M".
CURLOPT_REFERER	The contents of the "Referer: " header to be used in a HTTP request.
CURLOPT_SASL_AUTHZID	The authorization identity (authzid) for the transfer. Only applicable to the PLAIN SASL authentication mechanism where it is optional. When not specified, only the authentication identity (authcid) as specified by the username will be sent to the server, along with the password. The server will derive the authzid from the authcid when not provided, which it will then use internally.
CURLOPT_SERVICE_NAME	The authentication service name.	Added in cURL 7.43.0. Available since PHP 7.0.7.
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5	A string containing 32 hexadecimal digits. The string should be the MD5 checksum of the remote host's public key, and libcurl will reject the connection to the host unless the md5sums match. This option is only for SCP and SFTP transfers.	Added in cURL 7.17.1.
CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256	Base64-encoded SHA256 hash of the remote host's public key. The transfer will fail if the given hash does not match the hash the remote host provides.
CURLOPT_SSH_PUBLIC_KEYFILE	The file name for your public key. If not used, libcurl defaults to $HOME/.ssh/id_dsa.pub if the HOME environment variable is set, and just "id_dsa.pub" in the current directory if HOME is not set.	Added in cURL 7.16.1.
CURLOPT_SSH_PRIVATE_KEYFILE	The file name for your private key. If not used, libcurl defaults to $HOME/.ssh/id_dsa if the HOME environment variable is set, and just "id_dsa" in the current directory if HOME is not set. If the file is password-protected, set the password with CURLOPT_KEYPASSWD.	Added in cURL 7.16.1.
CURLOPT_SSL_CIPHER_LIST	A list of ciphers to use for SSL. For example, RC4-SHA and TLSv1 are valid cipher lists.
CURLOPT_SSL_EC_CURVES	A colon delimited list of elliptic curve algorithms. For example, X25519:P-521 is a valid list of two elliptic curves. This option defines the client's key exchange algorithms in the SSL handshake, if the SSL backend cURL is built to use supports it.
CURLOPT_SSLCERT	The name of a file containing a PEM formatted certificate.
CURLOPT_SSLCERTPASSWD	The password required to use the CURLOPT_SSLCERT certificate.
CURLOPT_SSLCERTTYPE	The format of the certificate. Supported formats are "PEM" (default), "DER", and "ENG". As of OpenSSL 0.9.3, "P12" (for PKCS#12-encoded files) is also supported.	Added in cURL 7.9.3.
CURLOPT_SSLENGINE	The identifier for the crypto engine of the private SSL key specified in CURLOPT_SSLKEY.
CURLOPT_SSLENGINE_DEFAULT	The identifier for the crypto engine used for asymmetric crypto operations.
CURLOPT_SSLKEY	The name of a file containing a private SSL key.
CURLOPT_SSLKEYPASSWD	The secret password needed to use the private SSL key specified in CURLOPT_SSLKEY. Note: Since this option contains a sensitive password, remember to keep the PHP script it is contained within safe.
CURLOPT_SSLKEYTYPE	The key type of the private SSL key specified in CURLOPT_SSLKEY. Supported key types are "PEM" (default), "DER", and "ENG".
CURLOPT_TLS13_CIPHERS	The list of cipher suites to use for the TLS 1.3 connection. The list must be syntactically correct, it consists of one or more cipher suite strings separated by colons. This option is currently used only when curl is built to use OpenSSL 1.1.1 or later. If you are using a different SSL backend you can try setting TLS 1.3 cipher suites by using the CURLOPT_SSL_CIPHER_LIST option.	Available since PHP 7.3.0 and libcurl >= cURL 7.61.0. Available when built with OpenSSL >= 1.1.1.
CURLOPT_UNIX_SOCKET_PATH	Enables the use of Unix domain sockets as connection endpoint and sets the path to the given string.	Added in cURL 7.40.0. Available since PHP 7.0.7.
CURLOPT_URL	The URL to fetch. This can also be set when initializing a session with curl_init().
CURLOPT_USERAGENT	The contents of the "User-Agent: " header to be used in a HTTP request.
CURLOPT_USERNAME	The user name to use in authentication.	Added in cURL 7.19.1.
CURLOPT_PASSWORD	The password to use in authentication.	Added in cURL 7.19.1.
CURLOPT_USERPWD	A username and password formatted as "[username]:[password]" to use for the connection.
CURLOPT_XOAUTH2_BEARER	Specifies the OAuth 2.0 access token.	Added in cURL 7.33.0. Available since PHP 7.0.7.

value should be an array for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_CONNECT_TO	Connect to a specific host and port instead of the URL's host and port. Accepts an array of strings with the format HOST:PORT:CONNECT-TO-HOST:CONNECT-TO-PORT.	Added in cURL 7.49.0. Available since PHP 7.0.7.
CURLOPT_HTTP200ALIASES	An array of HTTP 200 responses that will be treated as valid responses and not as errors.	Added in cURL 7.10.3.
CURLOPT_HTTPHEADER	An array of HTTP header fields to set, in the format array('Content-type: text/plain', 'Content-length: 100')
CURLOPT_POSTQUOTE	An array of FTP commands to execute on the server after the FTP request has been performed.
CURLOPT_PROXYHEADER	An array of custom HTTP headers to pass to proxies.	Added in cURL 7.37.0. Available since PHP 7.0.7.
CURLOPT_QUOTE	An array of FTP commands to execute on the server prior to the FTP request.
CURLOPT_RESOLVE	Provide a custom address for a specific host and port pair. An array of hostname, port, and IP address strings, each element separated by a colon. In the format: array("example.com:80:127.0.0.1")	Added in cURL 7.21.3.

value should be a stream resource (using fopen(), for example) for the following values of the option parameter:

Option	Set value to
CURLOPT_FILE	The file that the transfer should be written to. The default is STDOUT (the browser window).
CURLOPT_INFILE	The file that the transfer should be read from when uploading.
CURLOPT_STDERR	An alternative location to output errors to instead of STDERR.
CURLOPT_WRITEHEADER	The file that the header part of the transfer is written to.

value should be the name of a valid function or a Closure for the following values of the option parameter:

Option	Set value to	Notes
CURLOPT_HEADERFUNCTION	A callback accepting two parameters. The first is the cURL resource, the second is a string with the header data to be written. The header data must be written by this callback. Return the number of bytes written.
CURLOPT_PASSWDFUNCTION	A callback accepting three parameters. The first is the cURL resource, the second is a string containing a password prompt, and the third is the maximum password length. Return the string containing the password.	Removed as of PHP 7.3.0.
CURLOPT_PROGRESSFUNCTION	A callback accepting five parameters. The first is the cURL resource, the second is the total number of bytes expected to be downloaded in this transfer, the third is the number of bytes downloaded so far, the fourth is the total number of bytes expected to be uploaded in this transfer, and the fifth is the number of bytes uploaded so far. Note: The callback is only called when the CURLOPT_NOPROGRESS option is set to false. Return a non-zero value to abort the transfer. In which case, the transfer will set a CURLE_ABORTED_BY_CALLBACK error.
CURLOPT_READFUNCTION	A callback accepting three parameters. The first is the cURL resource, the second is a stream resource provided to cURL through the option CURLOPT_INFILE, and the third is the maximum amount of data to be read. The callback must return a string with a length equal or smaller than the amount of data requested, typically by reading it from the passed stream resource. It should return an empty string to signal EOF.
CURLOPT_WRITEFUNCTION	A callback accepting two parameters. The first is the cURL resource, and the second is a string with the data to be written. The data must be saved by this callback. It must return the exact number of bytes written or the transfer will be aborted with an error.
CURLOPT_XFERINFOFUNCTION	A callback accepting two parameters. Has a similar purpose as CURLOPT_PROGRESSFUNCTION but is more modern and the preferred option from cURL.	Added in 7.32.0. Available as of PHP 8.2.0.

Other values:

Option	Set value to
CURLOPT_SHARE	A result of curl_share_init(). Makes the cURL handle to use the data from the shared handle.