预定义常量

允许使用抽象 Unix 域套接字而不是与主机建立 TCP 连接，并将路径设置为指定 string。此选项与 CURLOPT_UNIX_SOCKET_PATH 具有相同的语义。这两个选项共享相同的存储，因此每个句柄只能设置其中一个。自 PHP 7.3.0 和 cURL 7.53.0 起可用。

设置 string，其中包含 HTTP 请求中发送的 Accept-Encoding: 标头的内容。设置为 null 可禁用发送 Accept-Encoding: 标头。默认为 null。自 cURL 7.21.6 起可用。

使用活跃 FTP 连接时等待服务器连接回 cURL 的最大毫秒数。此选项接受任何可以转换为有效 int 的值。默认为 60000 毫秒。自 cURL 7.24.0 起可用。

连接到 IPv6 地址时使用的范围 ID 值。此选项接受任何可以转换为有效 int 的值。默认为 0。自 cURL 7.19.0 起可用。

传递 string，其中包含 cURL 的文件名，用作 Alt-Svc 缓存文件，从中读取现有缓存内容，并可能在传输后将其写回，除非通过 CURLOPT_ALTSVC_CTRL 设置了 CURLOPT_ALTSVC_CTRL。自 PHP 8.2.0 和 cURL 7.64.1 起可用。

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. Set to any of the CURLALTSVC_* constants. Defaults to Alt-Svc handling being disabled. Available as of PHP 8.2.0 and cURL 7.64.1.

Setting this option to 1 will cause FTP uploads to append to the remote file instead of overwriting it. Defaults to 0. Available as of cURL 7.17.0.

true 时将根据 Location: 重定向时，自动设置 header 中的 Referer: 信息。默认是 0。自 cURL 7.1.0 起可用。

Provides AWS V4 signature authentication on HTTP(S) header as a string. This option overrides any other authentication types that have been set in CURLOPT_HTTPAUTH. This method cannot be combined with other authentication types. Available as of PHP 8.2.0 and cURL 7.75.0.

This constant is no longer used as of PHP 5.5.0. Deprecated as of PHP 8.4.0.

每次读取要使用的缓冲区大小。但不能保证此请求一定会得到满足。此选项接受任何可以转换为有效 int 的值。默认为 CURL_MAX_WRITE_SIZE（当前为 16kB）。自 cURL 7.10 起可用。

包含一个或多个证书的文件名称的string，用于验证对等方。这仅在与 CURLOPT_SSL_VERIFYPEER 结合使用时才有意义。可能需要绝对路径。自 cURL 7.4.2 起可用。

A string with 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.

A string with a directory that holds multiple CA certificates. Use this option alongside CURLOPT_SSL_VERIFYPEER. Available as of cURL 7.9.8.

Sets the maximum time in seconds any in memory cached CA certificate store may be kept and reused for new connections. This option accepts any value that can be cast to a valid int. Defaults to 86400 (24 hours). Available as of PHP 8.3.0 and cURL 7.87.0

true 将在安全传输时输出 SSL 证书信息到 STDERR。需要开启 CURLOPT_VERBOSE 才有效。默认为 false。自 cURL 7.19.1 起可用。

在尝试连接时等待的秒数。设置为 0，则无限等待。此选项接受任何可以转换为有效 int 的值。默认 300。自 cURL 7.7.0 起可用。

尝试连接等待的时间，以毫秒为单位。设置为 0，则无限等待。如果 cURL 编译时使用系统标准的名称解析器（standard system name resolver），那部分的连接仍旧使用以秒计的超时解决方案，最小超时时间还是一秒钟。此选项接受任何可以转换为有效 int 的值。默认 300000。自 cURL 7.16.2 起可用。

true 将让库执行所有需要的代理、验证、连接过程，但不传输数据。此选项用于 HTTP、SMTP 和 POP3。默认是 false。自 cURL 7.15.2 起可用。

连接到指定主机和端口，从而替换 URL 中的主机和端口。接受 string 格式的 array：HOST:PORT:CONNECT-TO-HOST:CONNECT-TO-PORT。自 PHP 7.0.7 和 cURL 7.49.0 起可用。

包含 HTTP 请求中使用的 Cookie: header 内容的 string。请注意，多个 Cookie 之间用分号分隔，后跟一个空格（例如，fruit=apple; colour=red）。自 cURL 7.1.0 起可用。

包含 cookie 数据的文件的名称 string。cookie 文件可以是 Netscape 格式，也可以只是转储到文件中的纯 HTTP 样式标头。如果名称为空 string，则不会加载任何 cookie，但仍启用 cookie 处理。自 cURL 7.1.0 起可用。

string，包含调用句柄的析构函数时用于保存所有内部 cookie 的文件的名称。自 cURL 7.9.0 起可用。

cookie string（即 Netscape/Mozilla 的单行格式，或常规 HTTP 样式的 Set-Cookie header）将单个 cookie 添加到内部 cookie 存储中。 ALL 擦除内存中保存的所有 cookie , SESS 擦除内存中保存的所有会话 cookie , FLUSH 将所有已知的 cookie 写入到 CURLOPT_COOKIEJAR 指定的文件 , RELOAD 从 CURLOPT_COOKIEFILE 指定的文件中加载所有 cookie . 自 cURL 7.14.1 起可用。

设为 true 时将开启新的 cookie“会话”。将强制 cURL 忽略之前会话时存的其他 cookie。cURL 在默认情况下无论是否为会话，都会储存、加载所有 cookie。会话 cookie 是指没有过期时间，只存活在会话之中。自 cURL 7.9.7 起可用。

true 表示将 Unix 换行符转换成 CRLF 换行符。自 cURL 7.1.0 起可用。

Pass a string naming a file with the concatenation of CRL (Certificate Revocation List) (in PEM format) to use in the certificate validation that occurs during the SSL exchange. When cURL is built to use GnuTLS, there is no way to influence the use of CRL passed to help in the verification process. When cURL is built with OpenSSL support, X509_V_FLAG_CRL_CHECK and X509_V_FLAG_CRL_CHECK_ALL are both set, requiring CRL check against all the elements of the certificate chain if a CRL file is passed. Also note that CURLOPT_CRLFILE implies CURLSSLOPT_NO_PARTIALCHAIN as of cURL 7.71.0 due to an OpenSSL bug. Available as of cURL 7.19.0.

HTTP 请求时，使用自定义的请求方法来代替 GET 或 HEAD。对 DELETE 或者其他更隐蔽的 HTTP 请求有用。有效值如 GET、POST，CONNECT 等等；也就是说，不要在这里输入整行 HTTP 请求。例如输入 GET /index.html HTTP/1.0\r\n\r\n 是不正确的。此选项接受 string 或 null。自 cURL 7.1.0 起可用。

注意:

在没有首先确保服务器支持自定义请求方法的情况下，不要执行此操作。

URL 缺少协议的时候，使用 string 格式的默认协议。自 PHP 7.0.7 和 cURL 7.45.0 起可用。

Setting this option to 1 will have different effects based on the protocol it is used with. FTP and SFTP based URLs will list only the names of files in a directory. POP3 will list the email message or messages on the POP3 server. For FILE, this option has no effect as directories are always listed in this mode. Using this option with CURLOPT_WILDCARDMATCH will prevent the latter from having any effect. Defaults to 0. Available as of cURL 7.17.0.

true to not allow URLs that include a username. Usernames are allowed by default. Available as of PHP 7.3.0 and cURL 7.61.0.

设置在内存中缓存 DNS 的时间，默认为 120 秒（2 分钟）。此选项接受任何可以转换为有效 int 的值。自 cURL 7.9.3 起可用。

Set the name of the network interface that the DNS resolver should bind to. This must be an interface name (not an address). This option accepts a string or null. Available as of PHP 7.0.7 and cURL 7.33.0

Set the local IPv4 address that the resolver should bind to. The argument should contain a single numerical IPv4 address. This option accepts a string or null. Available as of PHP 7.0.7 and cURL 7.33.0.

Set the local IPv6 address that the resolver should bind to. The argument should contain a single numerical IPv6 address. This option accepts a string or null. Available as of PHP 7.0.7 and cURL 7.33.0.

Pass a string with a comma-separated list of DNS servers to be used instead of the system default (e.g.: 192.168.1.100,192.168.1.101:8080). Available as of cURL 7.24.0.

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. Available as of PHP 7.3.0 and cURL 7.60.0.

true 表示使用全局 DNS 缓存。此选项非线程安全。如果 PHP 是为非线程使用（CLI、FCGI、Apache2-Prefork 等）构建的，则默认情况下会有条件性的启用此选项。自 cURL 7.9.3 起可用，自 cURL 7.11.1 起弃用。自 PHP 8.4 起，此选项不再有效。

Set to 2 to verify the DNS-over-HTTPS server's SSL certificate name fields against the host name. Available as of PHP 8.2.0 and cURL 7.76.0.

Set to 1 to enable and 0 to disable verification of the authenticity of the DNS-over-HTTPS server's SSL certificate. Available as of PHP 8.2.0 and cURL 7.76.0.

Set to 1 to enable and 0 to disable the verification of the status of the DNS-over-HTTPS server certificate using the "Certificate Status Request" TLS extension (OCSP stapling). Available as of PHP 8.2.0 and cURL 7.76.0.

Provides the DNS-over-HTTPS URL. This option accepts a string or null. Available as of PHP 8.1.0 and cURL 7.62.0.

Like CURLOPT_RANDOM_FILE, except a filename to an Entropy Gathering Daemon socket. Available as of cURL 7.7.0 and deprecated as of cURL 7.84.0.

The contents of the Accept-Encoding: header as a string. This enables decoding of the response. Supported encodings are: identity, deflate, gzip. If an empty string is set, a header containing all supported encoding types is sent. Available as of cURL 7.10 and deprecated as of cURL 7.21.6.

Expect: 100-continue 响应的超时时间，以毫秒为单位。默认为 1000 毫秒。此选项接受任何可以转换为有效 int 的值。自 PHP 7.0.7 和 cURL 7.36.0 起可用。

当 HTTP 状态码大于等于 400，true 将显示错误详情。默认情况下将返回页面，忽略 HTTP 代码。自 cURL 7.1.0 起可用。

Accepts a file handle resource to the file that the transfer should be written to. The default is STDOUT (the browser window). Available as of cURL 7.1.0 and deprecated as of cURL 7.9.7.

设置为 true 时，会尝试获取远程文档中的修改时间信息。此值可通过 curl_getinfo() 函数的 CURLINFO_FILETIME 选项获取。自 cURL 7.5.0 起可用。

Pass a callable that will be used for wildcard matching. The signature of the callback should be:

curlHandle

The cURL handle.

pattern

The wildcard pattern.

string

The string to run the wildcard pattern matching on.

设置为 true 时将会根据服务器返回 HTTP header 中的 Location: 重定向。参 CURLOPT_MAXREDIRS。当 open_basedir 启用时，此常量无效。自 cURL 7.1.0 起可用。

设置为 true 后，在完成交互以后强制断开连接，不能在连接池中重用。自 cURL 7.7.0 起可用。

设置为 true 强制获取新连接，而不是缓存中的连接。自 cURL 7.7.0 起可用。

设置为 true 时为追加写入文件，而不是覆盖。自 cURL 7.1.0 起可用并于 cURL 7.16.4 起弃用。

CURLOPT_TRANSFERTEXT 的别名。请改用 CURLOPT_TRANSFERTEXT。自 cURL 7.1 起可用，自 cURL 7.11.1 起弃用，最后在 cURL 7.15.5 中可用。自 PHP 7.3.0 起移除。

设置为 true 时只列出 FTP 目录的名称。自 cURL 7.1.0 起可用并于 cURL 7.16.4 起弃用。

A string 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 system's default IP address. This option accepts a string or null. Available as of cURL 7.1.0.

将 FTP over SSL 身份验证方法（如果已启用）设置为任何 CURLFTPAUTH_* 常量。默认 CURLFTPAUTH_DEFAULT。自 cURL 7.12.2 起可用。

Pass a string that will be sent as account information over FTP (using the ACCT command) after username and password has been provided to the server. Set to null to disable sending the account information. Defaults to null. Available as of cURL 7.13.0.

Pass a string that will be used to try to authenticate over FTP if the USER/PASS negotiation fails. Available as of cURL 7.15.5.

设置为 true 时在 FTP 操作遇到当前不存在的路径时会创建缺失的目录。自 cURL 7.10.7 起可用。

Tell cURL which method to use to reach a file on a FTP(S) server. Possible values are any of the CURLFTPMETHOD_* constants. Defaults to CURLFTPMETHOD_MULTICWD. Available as of cURL 7.15.1.

A timeout in seconds cURL will wait for a response from an FTP server. This option overrides CURLOPT_TIMEOUT. This option accepts any value that can be cast to a valid int. This option name is replaced with CURLOPT_SERVER_RESPONSE_TIMEOUT, available as of PHP 8.4.0. Available as of cURL 7.10.8 and deprecated as of cURL 7.85.0.

If this option is set to 1 cURL will not use the IP address the server suggests in its 227-response to cURL's PASV command but will use the IP address it used for the connection. The port number received from the 227-response will not be ignored by cURL. Defaults to 1 as of cURL 7.74.0 and 0 prior to that. Available as of cURL 7.15.0.

Available as of cURL 7.11.0 and deprecated as of cURL 7.16.4.

This option makes cURL use CCC (Clear Command Channel) which shuts down the SSL/TLS layer after authenticating making the rest of the control channel communication unencrypted. Use one of the CURLFTPSSL_CCC_* constants. Defaults to CURLFTPSSL_CCC_NONE. Available as of cURL 7.16.1.

设置为 true 时，当 FTP 下载时，使用 EPRT (和 LPRT)命令。设置为 false 时禁用 EPRT 和 LPRT，仅仅使用 PORT 命令。自 cURL 7.10.5 起可用。

设置为 true 时，在 FTP 传输过程中，回到 PASV 模式前，先尝试 EPSV 命令。设置为 false 时禁用 EPSV。自 cURL 7.9.2 起可用。

Set to 1 to send a PRET command before PASV (and EPSV). Has no effect when using the active FTP transfers mode. Defaults to 0. Available as of cURL 7.20.0.

Set to CURLGSSAPI_DELEGATION_FLAG to allow unconditional GSSAPI credential delegation. Set to CURLGSSAPI_DELEGATION_POLICY_FLAG to delegate only if the OK-AS-DELEGATE flag is set in the service ticket. Defaults to CURLGSSAPI_DELEGATION_NONE. Available as of cURL 7.22.0.

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. This option accepts any value that can be cast to a valid int. Available as of PHP 7.3.0 and cURL 7.59.0

true to send an HAProxy PROXY protocol v1 header at the start of the connection. The default action is not to send this header. Available as of PHP 7.3.0 and cURL 7.60.0.

设置为 true 以将 header 包含在发送到 CURLOPT_WRITEFUNCTION 定义的回调的输出中。自 cURL 7.1.0 起可用。

A callable with the following signature:

curlHandle

The cURL handle.

headerData

The header data which must be written by the callback.

将 HTTP header 同时发送到代理和主机或单独发送。可能的值是 CURLHEADER_* 常量。自 cURL 7.42.1 起默认 CURLHEADER_SEPARATE，在此之前默认为 CURLHEADER_UNIFIED。自 PHP 7.0.7 和 cURL 7.37.0 起可用。

string with HSTS (HTTP Strict Transport Security) cache file name or null to allow HSTS without reading from or writing to any file and clear the list of files to read HSTS data from. Available as of PHP 8.2.0 and cURL 7.74.0.

Accepts a bitmask of HSTS (HTTP Strict Transport Security) features defined by the CURLHSTS_* constants. Available as of PHP 8.2.0 and cURL 7.74.0.

是否允许 HTTP/0.9 响应。从 cURL 7.66.0 起默认为 false；以前默认为 true。分别自 PHP 7.3.15 和 7.4.3 以及 cURL 7.64.0 起可用。

An array of HTTP 200 responses that will be treated as valid responses and not as errors. Available as of cURL 7.10.3.

使用的 HTTP 验证方法。选项有： CURLAUTH_BASIC, CURLAUTH_DIGEST, CURLAUTH_GSSNEGOTIATE, CURLAUTH_NTLM, CURLAUTH_AWS_SIGV4, CURLAUTH_ANY, CURLAUTH_ANYSAFE。如果使用多种方法，cURL 将轮询服务器以查看它支持哪些方法并选择最佳方法。CURLAUTH_ANY 设置所有的位。cURL 将自动选择它认为最安全的一个。CURLAUTH_ANYSAFE 设置了除 CURLAUTH_BASIC 以外所有的位。cURL 将自动选择它认为最安全的一个。自 cURL 7.10.6 起可用。

设置为 true 时会设置 HTTP 方法为 GET，由于默认是 GET，所以只有修改请求方法时才需要这个选项。自 cURL 7.8.1 起可用。

An array of HTTP header fields to set, in the format array('Content-type: text/plain', 'Content-length: 100') Available as of cURL 7.1.0.

true 会通过指定 HTTP 代理来传输。自 cURL 7.3.0 起可用。

false 时获取原始 HTTP 响应主体。自 cURL 7.16.2 起可用。

If set to 0, transfer decoding is disabled. If set to 1, transfer decoding is enabled. cURL does chunked transfer decoding by default unless this option is set to 0. Defaults to 1. Available as of cURL 7.16.2.

设置为 CURL_HTTP_VERSION_* 常量中的一个，以便 cURL 使用指定的 HTTP 版本。自 cURL 7.9.1 起可用。

If set to 1, ignore the Content-Length header in the HTTP response and ignore asking for or relying on it for FTP transfers. Defaults to 0. Available as of cURL 7.14.1.

Accepts a file handle resource to the file that the transfer should be read from when uploading. Available as of cURL 7.1.0 and deprecated as of cURL 7.9.7. Use CURLOPT_READDATA instead.

希望传给远程站点的文件字节大小。注意无法用这个选项阻止 cURL 发送更多的数据，确切发送什么取决于 CURLOPT_READFUNCTION。此选项接受任何可以转换为有效 int 的值。自 cURL 7.1.0 起可用。

Set to a string with the name of the outgoing network interface to use. This can be an interface name, an IP address or a host name. Available as of cURL 7.1.0.

允许应用程序选择在解析主机名时使用哪种 IP 地址。这仅在使用解析使用多个 IP 版本的地址的主机名时才有意义。设置为 CURL_IPRESOLVE_* 常量中的一个。默认为 CURL_IPRESOLVE_WHATEVER。自 cURL 7.10.8 起可用。

If set to a string naming a file holding a CA certificate in PEM format, an additional check against the peer certificate is performed to verify the issuer is indeed the one associated with the certificate provided by the option. For the result of the check to be considered a failure, this option should be used in combination with the CURLOPT_SSL_VERIFYPEER option. Available as of cURL 7.19.0.

Pass a string with binary data of a CA SSL certificate in PEM format. If set, an additional check against the peer certificate is performed to verify the issuer is the one associated with the certificate provided by the option. Available as of PHP 8.1.0 and cURL 7.71.0.

设置为 true 时，如果返回的 HTTP 代码等于或大于 300，则继续发送请求主体。默认操作是停止发送并关闭流或连接。适用于手动 NTLM 身份验证。大多数应用程序不需要此选项。自 PHP 7.3.0 和 cURL 7.51.0 起可用。

Set to a string with the password required to use the CURLOPT_SSLKEY or CURLOPT_SSH_PRIVATE_KEYFILE private key. Setting this option to null disables using a password for these options. Available as of cURL 7.17.0.

The KRB4 (Kerberos 4) security level. Any of the following string 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. Available as of cURL 7.3.0 and deprecated as of cURL 7.17.0.

Set the kerberos security level for FTP and also enables kerberos awareness. This should be set to one of the following strings: clear, safe, confidential, private. If the string is set but does not match one of these, private is used. Setting this option to null will disable kerberos support for FTP. Defaults to null. Available as of cURL 7.16.4.

Sets the local port number of the socket used for the connection. This option accepts any value that can be cast to a valid int. Defaults to 0. Available as of cURL 7.15.2.

The number of attempts cURL makes to find a working local port number, starting with the one set with CURLOPT_LOCALPORT. This option accepts any value that can be cast to a valid int. Defaults to 1. Available as of cURL 7.15.2.

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. Available as of PHP 7.0.7 and cURL 7.34.0.

传输速度，每秒字节数，根据 CURLOPT_LOW_SPEED_TIME 秒数统计是否因太慢而取消传输。此选项接受任何可以转换为有效 int 的值。自 cURL 7.1.0 起可用。

当传输速度小于 CURLOPT_LOW_SPEED_LIMIT 时(bytes/sec)，PHP 会判断是否因太慢而取消传输。此选项接受任何可以转换为有效 int 的值。自 cURL 7.1.0 起可用。

Set a string with the authentication address (identity) of a submitted message that is being relayed to another server. The address should not be specified within a pair of angled brackets (><). If an empty string is used then a pair of brackets are sent by cURL as required by RFC 2554. Available as of cURL 7.25.0.

Set a string with the sender's email address when sending SMTP mail. The email address should be specified with angled brackets (><) around it, which if not specified are added automatically. If this parameter is not specified then an empty address is sent to the SMTP server which might cause the email to be rejected. Available as of cURL 7.20.0.

Set to an array of strings with the recipients to pass to the server in an SMTP mail request. Each recipient should be specified within a pair of angled brackets (><). If an angled bracket is not used as the first character, cURL assumes a single email address has been provided and encloses that address within brackets. Available as of cURL 7.20.0.

设置为 1 以允许 RCPT TO 命令对某些收件人失败，这会使 cURL 忽略个别收件人的错误并继续处理其余已接受的收件人。如果所有收件人触发失败并且设置了此 flag，cURL 将中止 SMTP 对话并返回从最后一个 RCPT TO 命令收到的错误。自 cURL 8.2.0 起由 CURLOPT_MAIL_RCPT_ALLOWFAILS 取代。自 PHP 8.2.0 和 cURL 7.69.0 起可用。自 cURL 8.2.0 起弃用。

重新使用已存在连接时允许的最大空闲时间。默认最大时间设置为 118 秒。此选项接受任何可以转换为有效 int 的值。自 PHP 8.2.0 和 cURL 7.65.0 起可用。

允许的最大持久连接数。当达到限制时，将会关闭缓存中最早的连接，以防止增加已打开的连接数。此选项接受任何可以转换为有效 int 的值。自 cURL 7.7.0 起可用。

Sets the maximum accepted size (in bytes) of a file to download. If the file requested is found larger than this value, the transfer is aborted and CURLE_FILESIZE_EXCEEDED is returned. Passing 0 disables this option, and passing a negative size returns a CURLE_BAD_FUNCTION_ARGUMENT. If the file size is not known prior to the start of download, this option has no effect. For setting a size limit above 2GB, CURLOPT_MAXFILESIZE_LARGE should be used. As of cURL 8.4.0, this option also stops ongoing transfers if they reach this threshold. This option accepts any value that can be cast to a valid int. Defaults to 0. Available as of cURL 7.10.8.

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. This option accepts any value that can be cast to a valid int. Available as of PHP 8.2.0 and cURL 7.11.0.

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. This option accepts any value that can be cast to a valid int. Available as of PHP 8.2.0 and cURL 7.80.0.

指定最多的 HTTP 重定向次数，这个选项是和 CURLOPT_FOLLOWLOCATION 一起使用的。默认值 20 是为了防止无限重定向。设置为 -1 允许无限重定向，0 拒绝所有重定向。自 cURL 7.5.0 起可用。

如果下载速度超过了此速度（以每秒字节数来统计），即传输过程中累计的平均数，传输就会降速到这个参数的值。默认不限速。 This option accepts any value that can be cast to a valid int. Available as of cURL 7.15.5.

如果上传的速度超过了此速度（以每秒字节数来统计），即传输过程中累计的平均数，传输就会降速到这个参数的值。默认不限速。 This option accepts any value that can be cast to a valid int. Available as of cURL 7.15.5.

Set to a bitmask of CURLMIMEOPT_* constants. Currently there is only one available option: CURLMIMEOPT_FORMESCAPE. Available as of PHP 8.3.0 and cURL 7.81.0.

设置 true 时将完全静默，无论是何 cURL 函数。使用 CURLOPT_RETURNTRANSFER 代替。自 cURL 7.1.0 起可用，自 cURL 7.8.0 起弃用，最后在 cURL 7.15.5 中可用。自 PHP 7.3.0 起移除。

设置为 true 时，在连接建立时，访问 ~/.netrc 文件获取用户名和密码来连接远程站点。自 cURL 7.1.0 起可用。

Set a string containing the full path name to a .netrc file. If this option is omitted and CURLOPT_NETRC is set, cURL checks for a .netrc file in the current user's home directory. Available as of cURL 7.11.0.

Sets the value of the permissions (int) that is set on newly created directories on the remote server. The default value is 0755. The only protocols that can use this are sftp://, scp:// and file://. Available as of cURL 7.16.4.

Sets the value of the permissions (as an int) that are set on newly created files on the remote server. The default value is 0644. The only protocols that can use this are sftp://, scp:// and file://. Available as of cURL 7.16.4.

设置为 true 可从输出中排除正文。对于 HTTP(S)，cURL 会发出 HEAD 请求。对于大多数其他协议，cURL 根本不会要求正文数据。将其更改为 false 将导致正文数据包含在输出中。自 cURL 7.1.0 起可用。

设置为 true 时关闭 cURL 的传输进度。

注意:

PHP 自动设置此选项为 true，只有用于调试才需要改变设置。

Set a string consisting of a comma separated list of hostnames that do not require a proxy to get reached. Each name in this list is matched as either a domain which contains the hostname or the hostname itself. The only wildcard available in the string is a single * character which matches all hosts, effectively disabling the proxy. Setting this option to an empty string enables the proxy for all hostnames. Since cURL 7.86.0, IP addresses set with this option can be provided using CIDR notation. Available as of cURL 7.19.4.

true 时忽略所有的 cURL 函数传递给 PHP 进程的信号。在 SAPI 多线程传输时默认启用此选项，所以超时选项仍能使用。自 cURL 7.10 起可用。

A callable with the following signature:

curlHandle

The cURL handle.

passwordPrompt

A password prompt.

maximumPasswordLength

The maximum length of the password.

Set to a string with the password to use in authentication. Available as of cURL 7.19.1.

Set to true for cURL not alter URL paths before passing them on to the server. Defaults to false, which squashes sequences of /../ or /./ that may exist in the URL's path part which is supposed to be removed according to RFC 3986 section 5.2.4. Available as of PHP 7.0.7 and cURL 7.42.0.

Set a string with the pinned public key. The string can be the file name of the pinned public key in a PEM or DER file format. The string can also be any number of base64 encoded sha256 hashes preceded by sha256// and separated by ;. Available as of PHP 7.0.7 and cURL 7.39.0.

Set to true to wait for an existing connection to confirm whether it can do multiplexing and use it if it can before creating and using a new connection. Available as of PHP 7.0.7 and cURL 7.43.0.

An int with an alternative port number to connect to instead of the one specified in the URL or the default port for the used protocol. Available as of cURL 7.1.0.

设置为 true 用于执行 HTTP POST 请求。此请求使用 application/x-www-form-urlencoded header。默认为 false。自 cURL 7.1.0 起可用。

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. Available as of cURL 7.1.0.

An array of FTP command strings to execute on the server after the FTP request has been performed. Available as of cURL 7.1.0.

位掩码，CURL_REDIR_POST_301、CURL_REDIR_POST_302 和 CURL_REDIR_POST_303。当设置 CURLOPT_FOLLOWLOCATION 并发生了特定类型的重定向时，是否需要再次 HTTP POST 到重定向网址。自 cURL 7.19.1 起可用。

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 as of PHP 7.3.0 and cURL 7.52.0.

Set an array of FTP command strings to pass to the server after the transfer type is set. These commands are not performed when a directory listing is performed, only for file transfers. Available as of cURL 7.9.5.

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. Available as of cURL 7.10.3.

A callable with the following signature:

curlHandle

The cURL handle.

bytesToDownload

The total number of bytes expected to be downloaded in this transfer.

bytesDownloaded

The number of bytes downloaded so far.

bytesToUpload

The total number of bytes expected to be uploaded in this transfer.

bytesUploaded

The number of bytes uploaded so far.

注意:

The callback is only called when the CURLOPT_NOPROGRESS option is set to false.

Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols cURL may use in the transfer. Defaults to CURLPROTO_ALL, ie. cURL will accept all protocols it supports. See also CURLOPT_REDIR_PROTOCOLS. Available as of cURL 7.19.4 and deprecated as of cURL 7.85.0.

Set to a string with a comma separated list of case insensitive protocol names (URL schemes) to allow in the transfer. Set to ALL to enable all protocols. By default, cURL accepts all protocols it was built with support for. Available protocols are: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPE, RTMPS, RTMPT, RTMPTE, RTMPTS, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS, WSS. Available as of PHP 8.3.0 and cURL 7.85.0.

A string with the HTTP proxy to tunnel requests through. This should be the hostname, the dotted numerical IP address or a numerical IPv6 address written within [brackets]. Available as of cURL 7.1.0.

A bitmask of the HTTP authentication method(s) (CURLAUTH_* constants) to use for the proxy connection. For proxy authentication, only CURLAUTH_BASIC and CURLAUTH_NTLM are currently supported. Defaults to CURLAUTH_BASIC. Available as of cURL 7.10.7.

An array of custom HTTP header strings to pass to proxies. Available as of PHP 7.0.7 and cURL 7.37.0.

Set a string with the password to be used for authentication with the proxy. Available as of cURL 7.19.1.

An int with the port number of the proxy to connect to. This port number can also be set in CURLOPT_PROXY. Setting this to zero makes cURL use the default proxy port number or the port number specified in the proxy URL string. Available as of cURL 7.1.0.

Sets the type of the proxy to one of the CURLPROXY_* constants. Defaults to CURLPROXY_HTTP. Available as of cURL 7.10.

Set a string with the username to be used for authentication with the proxy. Available as of cURL 7.19.1.

A string with a username and password formatted as [username]:[password] to use for the connection to the proxy. Available as of cURL 7.1.0.

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 cURL's cacert bundle is assumed to be stored. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with 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 cURL's cacert bundle is assumed to be stored. Available as of PHP 8.2.0 and cURL 7.77.0.

A string with the directory holding multiple CA certificates to verify the HTTPS proxy with. Available as of PHP 7.3.0 and cURL 7.52.0.

Set to a string with 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 as of PHP 7.3.0 and cURL 7.52.0.

Proxy issuer SSL certificate filename string. Available as of PHP 8.1.0 and cURL 7.71.0.

A string with the proxy issuer SSL certificate. Available as of PHP 8.1.0 and cURL 7.71.0.

Set the string be used as the password required to use the CURLOPT_PROXY_SSLKEY private key. A passphrase is not needed to load a certificate but one is needed to load a private key. This option is for connecting to an HTTPS proxy, not an HTTPS server. Available as of PHP 7.3.0 and cURL 7.52.0.

Set the pinned public key for HTTPS proxy. The string can be the file name of the pinned public key which is expected to be in a PEM or DER file format. The string can also be any number of base64 encoded sha256 hashes preceded by sha256// and separated by ;. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the proxy authentication service name. Available as of PHP 7.0.7, cURL 7.43.0 (for HTTP proxies) and cURL 7.49.0 (for SOCKS5 proxies).

A string with the file name of the 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 used for authentication as it is named in the security database. If a file from the current directory is to be used, it must be prefixed with ./ in order to avoid confusion with a nickname. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the format of the 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 as of PHP 7.3.0 and cURL 7.52.0.

A string with the SSL proxy client certificate. Available as of PHP 8.1.0 and cURL 7.71.0.

A string with the file name of the 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 if built with TLS enabled. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the format of the private key. Supported formats are: PEM, DER, ENG. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the private key for connecting to the HTTPS proxy. Available as of PHP 8.1.0 and cURL 7.71.0.

Set the preferred HTTPS proxy TLS version to one of the CURL_SSLVERSION_* constants. Defaults to CURL_SSLVERSION_DEFAULT.

A string with a colon-separated list of ciphers to use for the connection to the HTTPS proxy. When used with OpenSSL commas and spaces are also acceptable as separators, and !, - and + can be used as operators. Available as of PHP 7.3.0 and cURL 7.52.0.

Set proxy SSL behavior options, which is a bitmask of the CURLSSLOPT_* constants. Available as of PHP 7.3.0 and cURL 7.52.0.

设置为 2 以根据代理名称验证 HTTPS 代理的证书名称字段。设置为 0 时，无论证书中使用的名称如何，连接都会成功。谨慎使用该能力！在 cURL 7.28.0 及更早版本中将其设置为 1 作为调试选项。在 cURL 7.28.1 到 7.65.3 中设置为 1，则返回 CURLE_BAD_FUNCTION_ARGUMENT。自 cURL 7.66.0 起，视 1 和 2 为相同的值。默认为 2。在生产环境中，此选项的值应保持为 2。从 PHP 7.3.0 和 cURL 7.52.0 开始可用。

false 时阻止 CURL 验证对等证书（peer's certificate）。可以使用 CURLOPT_CAINFO 选项指定要验证的备用证书，或者使用 CURLOPT_CAPATH 选项指定证书目录。设置为 false 时，无论如何验证对等证书都会成功。默认为 true。自 PHP 7.3.0 和 cURL 7.52.0 起可用。

A string with a colon-separated list of ciphers to use for the connection to the TLS 1.3 connection to a proxy. This option is currently used only when cURL is built to use OpenSSL 1.1.1 or later. When using a different SSL backend the TLS 1.3 cipher suites can be set with the CURLOPT_PROXY_SSL_CIPHER_LIST option. Available as of PHP 7.3.0 and cURL 7.61.0.

A string with 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 as of PHP 7.3.0 and cURL 7.52.0.

The method of the TLS authentication used for the HTTPS connection. Supported method is SRP.

注意:

Secure Remote Password (SRP) authentication for TLS provides mutual authentication if both sides have a shared secret. To use TLS-SRP, the CURLOPT_PROXY_TLSAUTH_USERNAME and CURLOPT_PROXY_TLSAUTH_PASSWORD options must also be set.

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 as of PHP 7.3.0 and cURL 7.52.0.

Set to 1 to set the transfer mode (binary or ASCII) for FTP transfers done via an HTTP proxy, by appending type=a or type=i to the URL. Without this setting or it being set to 0, CURLOPT_TRANSFERTEXT has no effect when doing FTP via a proxy. Defaults to 0. Available as of cURL 7.18.0.

true 时允许 HTTP 发送文件。要被 PUT 的文件必须在 CURLOPT_READDATA 和CURLOPT_INFILESIZE 中设置。自 cURL 7.1.0 起可用并于 cURL 7.12.1 弃用。

Set to true for cURL to skip cleanup of resources when recovering from a timeout. This allows for a swift termination of the cURL process at the expense of a possible leak of associated resources. Available as of PHP 8.3.0 and cURL 7.87.0.

An array of FTP command strings to execute on the server prior to the FTP request. Available as of cURL 7.1.0.

A string with a filename to be used to seed the random number generator for SSL. Available as of cURL 7.7.0 and deprecated as of cURL 7.84.0.

A string with the 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. Set to null to disable requesting a byte range. Available as of cURL 7.1.0.

Sets a file pointer resource that will be used by the file read function set with CURLOPT_READFUNCTION. Available as of cURL 7.9.7.

A callable with the following signature:

curlHandle

The cURL handle.

streamResource

Stream resource provided to cURL through the option CURLOPT_READDATA.

maxAmountOfDataToRead

The maximum amount of data to be read.

Bitmask of CURLPROTO_* values which limit what protocols cURL may use in a transfer that it follows to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. This allows limiting specific transfers to only be allowed to use a subset of protocols in redirections. As of cURL 7.19.4, by default cURL will allow all protocols except for FILE and SCP. Prior to cURL 7.19.4, cURL would unconditionally follow to all supported protocols. See also CURLOPT_PROTOCOLS for protocol constant values. Available as of cURL 7.19.4 and deprecated as of cURL 7.85.0.

Set to a string with a comma separated list of case insensitive protocol names (URL schemes) to allow to follow to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. Set to ALL to enable all protocols. As of cURL 7.65.2 it defaults to FTP, FTPS, HTTP and HTTPS. From cURL 7.40.0 to 7.65.1, this defaults to all protocols except FILE, SCP, SMB and SMBS. Prior to cURL 7.40.0, this defaults to all protocols except FILE and SCP. Available protocols are: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPE, RTMPS, RTMPT, RTMPTE, RTMPTS, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS, WSS. Available as of PHP 8.3.0 and cURL 7.85.0.

A string with the contents of the Referer: header to be used in a HTTP request. Available as of cURL 7.1.0.

A string to use in the upcoming request instead of the path as extracted from the URL. Available as of PHP 7.3.0 and cURL 7.55.0.

Provide an array of colon-separated strings with custom addresses for specific host and port pairs in the following format: array( "example.com:80:127.0.0.1", "example2.com:443:127.0.0.2", ) Available as of cURL 7.21.3.

恢复传输时，传递字节为单位的偏移量（以字节为单位）。此选项接受任何可以转换为有效 int 的值。自 cURL 7.1.0 起可用。

true 将 curl_exec() 获取的信息以 string 返回，而不是直接输出。

Set an int with the CSEQ number to issue for the next RTSP request. Useful if the application is resuming a previously broken connection. The CSEQ increments from this new number henceforth. Defaults to 0. Available as of cURL 7.20.0.

Sets the kind of RTSP request to make. Must be one of the CURL_RTSPREQ_* constants. Available as of cURL 7.20.0.

Set an int with the CSEQ number to expect for the next RTSP Server to Client request. This feature (listening for Server requests) is unimplemented. Defaults to 0. Available as of cURL 7.20.0.

Set a string with the value of the current RTSP Session ID for the handle. Once this value is set to any non-null value, cURL returns CURLE_RTSP_SESSION_ERROR if the ID received from the server does not match. If set to null, cURL automatically sets the ID the first time the server sets it in a response. Defaults to null Available as of cURL 7.20.0.

Sets a string with the stream URI to operate on. If not set, cURL defaults to operating on generic server options by passing * in the place of the RTSP Stream URI. When working with RTSP, CURLOPT_RTSP_STREAM_URI indicates what URL to send to the server in the request header while the CURLOPT_URL indicates where to make the connection to. Available as of cURL 7.20.0.

Set the Transport: header for this RTSP session. Available as of cURL 7.20.0.

始终为 true，在 CURLOPT_POSTFIELDS 中禁用了对上传文件的 @ 前缀的支持，这意味着以 @ 开头的值可以作为字段安全地传递。上传可使用 CURLFile 替代。

The authorization identity (authzid) string 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. Available as of PHP 8.2.0 and cURL 7.66.0.

true 时开启，收到首包（first packet）后发送初始的响应（initial response）。自 PHP 7.0.7 和 cURL 7.31.0 起可用。

A string with the authentication service name. Available as of PHP 7.0.7 and cURL 7.43.0.

curl_share_init() 的结果。使 cURL 可以使用共享句柄中的数据。自 cURL 7.10 起可用。

用于 SOCKS5 验证方法。选项是： CURLAUTH_BASIC, CURLAUTH_GSSAPI, CURLAUTH_NONE。当设置了多种方法时，cURL 将轮询服务器以查看其支持哪些方法并选择最佳方法。默认为 CURLAUTH_BASIC|CURLAUTH_GSSAPI。使用 CURLOPT_PROXYUSERPWD 选项设置真实的用户名和密码。自 PHP 7.3.0 和 cURL 7.55.0 起可用。

Set to 1 to enable and 0 to disable the unprotected exchange of the protection mode negotiation as part of the GSSAPI negotiation. Available as of cURL 7.19.4.

Set a string holding the name of the SOCKS5 service. Defaults to rcmd. Available as of cURL 7.19.4 and deprecated as of cURL 7.49.0. Use CURLOPT_PROXY_SERVICE_NAME instead.

A bitmask consisting of one or more of the following constants: CURLSSH_AUTH_PUBLICKEY, CURLSSH_AUTH_PASSWORD, CURLSSH_AUTH_HOST, CURLSSH_AUTH_KEYBOARD, CURLSSH_AUTH_AGENT, CURLSSH_AUTH_ANY. Defaults to CURLSSH_AUTH_ANY. Available as of cURL 7.16.1.

true to enable, false to disable built-in SSH compression. Note that the server can disregard this request. Defaults to false. Available as of PHP 7.3.0 and cURL 7.56.0.

A callable that will be called when SSH host key verification is needed. The callback must have the following signature:

curlHandle

The cURL handle.

keyType

One of the CURLKHTYPE_* key types.

key

The key to check.

keyLength

The length of the key in bytes.

A string containing 32 hexadecimal digits which should contain the MD5 checksum of the remote host's public key, and cURL will reject the connection to the host unless the md5sums match. This option is only for SCP and SFTP transfers. Available as of cURL 7.17.1.

A string with the 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. Available as of PHP 8.2.0 and cURL 7.80.0.

设置为要使用的 known_host 文件的文件名，该文件应使用 libssh2 支持的 OpenSSH 文件格式。自 cURL 7.19.6 起可用。

私钥的文件名。如果未指定，cURL 会默认使用 $HOME/.ssh/id_dsa（如果设置了 HOME 环境变量的话），或者在 HOME 未设置的情况下，默认使用当前目录下的 id_dsa 文件。如果文件受密码保护，则需要使用 CURLOPT_KEYPASSWD 设置密码，自 cURL 7.16.1 起可用。

公钥的文件名。如果未指定，cURL 会默认使用 $HOME/.ssh/id_dsa.pub（如果设置了 HOME 环境变量的话），或者在 HOME 未设置的情况下，默认使用当前目录下的 id_dsa.pub 文件。自 cURL 7.16.1 起可用。

包含 PEM 格式证书的文件名称。自 cURL 7.1.0 起可用。

使用 CURLOPT_SSLCERT 证书所需的密码。自 cURL 7.1.0 起可用，自 cURL 7.17.0 起已弃用。

string 的证书格式。支持的格式有： PEM, DER, ENG, P12。 P12（用于 PKCS#12 编码文件）自 OpenSSL 0.9.3 起可用。默认 PEM。自 cURL 7.9.3 起可用。

包含 SSL 客户端证书的 string。自 PHP 8.1.0 和 cURL 7.71.0 起可用。

CURLOPT_SSLKEY 中指定私有 SSL 密钥的加密引擎的 string 标识符。自 cURL 7.9.3 起可用。

加密引擎的 string 标识符，用于非对称加密操作。自 cURL 7.9.3 起可用。

包含私有 SSL 密钥的文件名。自 cURL 7.9.3 起可用。

使用 CURLOPT_SSLKEY 中指定私有 SSL 密钥所需的秘密密码。

注意:

由于此选项包含敏感密码，请确保妥善保管包含该选项的 PHP 脚本。

CURLOPT_SSLKEY 中指定私有 SSL 密钥的秘钥类型。支持的密钥类型有： PEM, DER, ENG。默认为 PEM。自 cURL 7.9.3 起可用。

客户端证书的 string 私钥。自 PHP 8.1.0 和 cURL 7.71.0 起可用。

CURL_SSLVERSION_* 常量之一。

用于 TLS 1.2（1.1、1.0）连接的以冒号分隔的密码 string。自 cURL 7.9 起可用。

椭圆曲线算法的冒号分隔列表。例如，X25519:P-521 是两个椭圆曲线的有效列表。此选项定义 SSL 握手中的客户端密钥交换算法（如果 SSL 后端 cURL 编译为支持该算法）。自 PHP 8.2.0 和 cURL 7.73.0 起可用。

false 时禁用 SSL 握手中的 ALPN（如果 SSL 后端的 cURL 内建支持）用于协商到 http2。自 PHP 7.0.7 和 cURL 7.36.0 起可用。

false 时禁用 SSL 握手中的 NPN（如果 SSL 后端的 libcurl 内建支持），用于协商到 http2。自 PHP 7.0.7 和 cURL 7.36.0 起可用，并且自 cURL 7.86.0 起弃用。

true 表示启用，false 表示禁用 TLS 错误启动，这是 TLS 客户端在验证服务器 Finished 消息之前开始发送应用程序数据的模式。自 PHP 7.0.7 和 cURL 7.42.0 起可用。

设置 SSL 行为选项，是 CURLSSLOPT_* 常量的位掩码。默认未设置任何位。自 PHP 7.0.7 和 cURL 7.25.0 起可用。

设置为 0 以禁用，设置为 1 以启用 SSL 会话 ID 缓存。默认情况下，所有传输均启用缓存。自 cURL 7.16.0 起可用。

2 时验证 SSL 对等证书中的公用名称字段或主题备用名称（Subject Alternate Name，简称 SNA）字段是否与提供的主机名匹配。0 时不检查名称。不应使用 1。在生产环境中，此选项的值应保持为 2（默认值）。自 cURL 7.8.1 起可用。

false 时禁止 cURL 验证对等证书（peer's certificate）。要验证的交换证书可以在 CURLOPT_CAINFO 选项中设置，或在 CURLOPT_CAPATH 中设置证书目录。自 cURL 7.10 起默认为 true。自 cURL 7.10 起安装默认的 CA 证书包。自 cURL 7.4.2 起可用。

true 时启用或者 false 时禁用验证证书状态。自 PHP 7.0.7 和 cURL 7.41.0 起可用。

接受指向替代位置的文件句柄 resource，以将错误输出到 STDERR 以外的其他位置。自 cURL 7.1.0 起可用。

设置 stream weight 数值（1 和 256 之间的数字）。自 PHP 7.0.7 和 cURL 7.46.0 起可用。

当使用 CURLOPT_HTTPPROXYTUNNEL 并发出 CONNECT 请求时，设置为 true 以抑制来自用户 callback 函数 CURLOPT_HEADERFUNCTION 和 CURLOPT_WRITEFUNCTION 的代理 CONNECT 响应 header。默认为 false。自 PHP 7.3.0 和 cURL 7.54.0 起可用。

true 时启用或者 false 时禁用 TCP Fast Open。自 PHP 7.0.7 和 cURL 7.49.0 起可用。

如果设置为 1，将发送 TCP keepalive 探针。这些探针的延迟和频率可以通过 CURLOPT_TCP_KEEPIDLE 和 CURLOPT_TCP_KEEPINTVL 选项来控制，前提是操作系统支持它们。如果设置为 0（默认值），将禁用 keepalive 探针。可以使用 CURLOPT_TCP_KEEPCNT 选项设置最大探测次数。自 cURL 7.25.0 起可用。

设置延迟秒数，如果启用了 CURLOPT_TCP_KEEPALIVE，操作系统将在连接空闲时等待，然后再发送 keepalive 探针。并非所有操作系统都支持此选项。默认值为 60。自 cURL 7.25.0 起可用。

设置间隔（以秒为单位），如果启用了 CURLOPT_TCP_KEEPALIVE，操作系统将在发送 keepalive 探针之间等待。并非所有操作系统都支持此选项。默认值为 60。自 cURL 7.25.0 起可用。

设置 TCP 保持活动探测的最大数量。默认值为 9。自 PHP 8.4.0 和 cURL 8.9.0 起可用。

true 时禁用 TCP 的 Nagle 算法，就是减少网络上的小数据包数量。默认是 true。自 cURL 7.11.2 起可用。

设置要传递给 telnet 协商的由 string 组成的 array。变量应采用 >option=value< 格式。cURL 支持选项 TTYPE、XDISPLOC 和 NEW_ENV。自 cURL 7.7.0 起可用。

设置用于 TFTP 数据传输的块大小。有效范围为 8-65464 字节。如果未指定此选项，则使用默认值 512 字节。仅当远程服务器支持时才使用指定的块大小。如果服务器未返回选项确认或返回没有块大小的选项确认，则使用默认值 512 字节。自 cURL 7.19.4 起可用。

true 时不发送 TFTP 的 options 请求。默认为 false。自 PHP 7.0.7 和 cURL 7.48.0 起可用。

设置如何对待 CURLOPT_TIMEVALUE。使用 CURL_TIMECOND_IFMODSINCE，仅在页面 CURLOPT_TIMEVALUE 之后修改，才返回页面。没有修改则返回 304 Not Modified header，假设设置了 CURLOPT_HEADER 为 true。CURL_TIMECOND_IFUNMODSINCE 则起相反的效果。使用 CURL_TIMECOND_NONE 忽略 CURLOPT_TIMEVALUE 并始终返回页面。默认为 CURL_TIMECOND_IFMODSINCE。在 cURL 7.46.0 之前，默认值为 CURL_TIMECOND_IFMODSINCE。自 cURL 7.1.0 起可用。

允许 cURL 函数执行的最长秒数。默认值为 0，表示函数在传输过程中永不超时。自 cURL 7.1.0 起可用。

允许 cURL 允许执行的最长毫秒数。如果 cURL 编译时使用系统标准的名称解析器（standard system name resolver），那部分的连接仍旧使用以秒计的超时解决方案，最小超时时间还是一秒钟。默认值为 0，表示函数在传输过程中永不超时。自 cURL 7.16.2 起可用。

秒数，从 1970 年 1 月 1 日开始。这个时间将由 CURLOPT_TIMECONDITION 使用。默认 0。自 cURL 7.1.0 起可用。

自 1970 年 1 月 1 日以来的秒数。该时间将由 CURLOPT_TIMECONDITION 使用。默认为 0。此选项与 CURLOPT_TIMEVALUE 之间的区别在于参数的类型。“long”仅用于 32 位系统上，必须使用此选项来设置 2038 年以后的日期。自 PHP 7.3.0 和 cURL 7.59.0 起可用。

string，包含用于连接到 TLS 1.3 连接的以冒号分隔的密码套件列表。此选项目前仅在 cURL 构建为 OpenSSL 1.1.1 或更高版本时使用。当使用不同的 SSL 后端时，可以使用 CURLOPT_SSL_CIPHER_LIST 选项设置 TLS 1.3 密码套件。自 PHP 7.3.0 和 cURL 7.61.0 起可用。

设置用于 CURLOPT_TLSAUTH_TYPE 选项指定 TLS 身份验证方法的密码。同时也需要设置 CURLOPT_TLSAUTH_USERNAME 选项。此功能依赖于 TLS SRP，不适用于 TLS 1.3。自 cURL 7.21.4 起可用。

设置 TLS 身份验证方法的 string。支持的方法是 SRP（TLS 安全远程密码身份验证）。自 cURL 7.21.4 起可用。

设置 string，其中包含要用于 CURLOPT_TLSAUTH_TYPE 选项指定 TLS 身份验证方法的用户名。同时需要设置 CURLOPT_TLSAUTH_PASSWORD 选项。此功能依赖于 TLS SRP，不适用于 TLS 1.3。自 cURL 7.21.4 起可用。

设置为 1 以启用，设置为 0 以禁用在传出 HTTP 请求中请求压缩传输编码。如果服务器以压缩传输编码响应，cURL 将在接收时自动解压缩。默认为 0。自 cURL 7.21.6 起可用。

true 时 FTP 传输使用 ASCII 模式。对于 LDAP，会检索纯文本信息而非 HTML。在 Windows 系统上，系统不会把 STDOUT 设置成二进制模式。默认是 false。自 cURL 7.1.1 起可用。

启用时使用 Unix domain socket 作为连接端点，并设置路径为指定 string。设置为 null 时禁用。默认为 null。自 PHP 7.0.7 和 cURL 7.40.0 起可用。

true 时在使用 CURLOPT_FOLLOWLOCATION 重定向 header 中的多个 location 时继续发送用户名和密码信息，哪怕主机名已改变。默认为 false。自 cURL 7.10.4 起可用。

某些协议具有“连接维护”机制。这些机制通常会在现有连接上发送一些流量以保持处于活动状态。此选项定义连接维护间隔。目前，唯一具有连接维护机制的协议是 HTTP/2。当超过连接维护间隔时，将在连接上发送 HTTP/2 PING 帧。默认为 CURL_UPKEEP_INTERVAL_DEFAULT，目前为 60 秒。自 PHP 8.2.0 和 cURL 7.62.0 起可用。

true 时准备执行上传。默认 false。自 cURL 7.1.0 起可用。

cURL 上传缓冲区的首选缓冲区字节数。上传缓冲区默认为 64 KB。允许设置的最大缓冲区为 2 MB。允许设置的最小缓冲区为 16 KB。自 PHP 8.2.0 和 cURL 7.62.0 起可用。

要获取的 URL。也可以在 curl_init() 初始化会话时设置。自 cURL 7.1.0 起可用。

设置使用 FTP、SMTP、POP3、IMAP 等进行传输时所需的 SSL/TLS 级别。这些都是从纯文本开始并使用 STARTTLS 命令“升级”到 SSL 的协议。设置为 CURLUSESSL_* 常量之一。自 cURL 7.17.0 起可用。

HTTP 请求中 User-Agent: header 的内容。自 cURL 7.1.0 起可用。

身份验证时使用的用户名。自 cURL 7.19.1 起可用。

用于连接的用户名和密码，格式为 [username]:[password]。自 cURL 7.1.0 起可用。

true 时输出所有的信息，写入到 STDERR，或在 CURLOPT_STDERR 中指定的文件。默认 false。自 cURL 7.1.0 起可用。

设置为 1 以根据文件名模式传输多个文件。该模式可以指定为 CURLOPT_URL 选项的一部分，在 URL（文件名）的最后一部分使用类似 fnmatch 的模式（Shell 模式匹配）。自 cURL 7.21.0 起可用。

具有以下签名的 callable：

curlHandle

cURL 句柄。

data

要写入的数据

接受文件句柄 resource，将传输的 header 部分写入该文件。自 cURL 7.1.0 起可用。

接受位掩码设置 WebSocket 行为选项。唯一可用的选项是 CURLWS_RAW_MODE。默认为 0。自 PHP 8.3.0 和 cURL 7.86.0 起可用。

具有以下签名的 callable：

curlHandle

cURL 句柄。

bytesToDownload

本次传输预计下载的总字节数。

bytesDownloaded

迄今已下载的字节数。

bytesToUpload

本次传输预计上传的总字节数。

bytesUploaded

迄今已上传的字节数。

cURL 将等待来自 FTP、SFTP、IMAP、SCP、SMTP 或 POP3 服务器响应的超时秒数。此选项取代了现有的 CURLOPT_FTP_RESPONSE_TIMEOUT 选项，该选项在 cURL 7.85.0 中已弃用。自 PHP 8.4.0 起可用。

指定 OAuth 2.0 访问 token。设置为 null 以禁用。默认为 null。自 PHP 7.0.7 和 cURL 7.33.0 起可用。

具有以下签名的 callable，在建立连接之后但在发送请求负载（例如，HTTP 连接的 GET/POST/DELETE 请求）之前调用，可用于根据源和目标 IP 地址和端口号中止或允许连接：

curlHandle

cURL 句柄。

destination_ip

使用此连接建立的远程服务器的主 IP。对于 FTP，这是控制连接的 IP。IPv6 地址不带括号。

local_ip

此连接的原始 IP。IPv6 地址不带括号。

destination_port

使用此连接建立的远程服务器上的主端口号。对于 FTP，这是控制连接的端口。根据协议的不同，这可能是 TCP 或 UDP 端口号。

local_port

此连接的发起端口号。根据协议的不同，这可能是 TCP 或 UDP 端口号。

自 PHP 8.4.0 起可用。此选项需要启用 CURLOPT_VERBOSE 选项。callable 来替换标准 cURL 详细输出。此回调在请求的各个阶段使用详细调试信息进行调用。回调应与以下签名匹配：

curlHandle

cURL 句柄。

type

下列常量之一表示 data 值的类型：

常量	描述
CURLINFO_TEXT (int)	信息文本。
CURLINFO_HEADER_IN (int)	从对等方接受的 header（或者类似 header）值。
CURLINFO_HEADER_OUT (int)	header（或者类 header） 数据发送给对等方。
CURLINFO_DATA_IN (int)	从对等方接收到的未处理协议数据。即使数据已编码或压缩，也不会向此回调提供解码或解压缩后的数据。
CURLINFO_DATA_OUT (int)	发送给对等方的协议数据。
CURLINFO_SSL_DATA_IN (int)	从对等方接收的 SSL/TLS（二进制）数据。
CURLINFO_SSL_DATA_OUT (int)	发送给对等方的 SSL/TLS（二进制）数据。

data

type 参数表示的类型的详细调试数据。

传递 callable 以注册处理服务器推送且应具有以下签名：

parent_ch

父级 cURL 句柄（客户端发出的请求）。

pushed_ch

推送请求的新 cURL 句柄。

headers

推送 promise header。