curl_version_info(3)

NAME
curl_version_info - returns runtime libcurl version info

SYNOPSIS
#include <curl/curl.h>

curl_version_info_data *curl_version_info(CURLversion age);

DESCRIPTION
Returns a pointer to a filled in static struct with information about various features in the running version of libcurl. age should be set to the version of this functionality by the time you write your program. This way, libcurl always returns a proper struct that your program understands, while programs in the future might get a different struct. CURLVERSION_NOW is the most recent one for the library you have installed:
  data = curl_version_info(CURLVERSION_NOW);
Applications should use this information to judge if things are possible to do or not, instead of using compile-time checks, as dynamic/DLL libraries can be changed independent of applications.

This function can alter the returned static data as long as curl_global_init(3) has not been called. It is therefore not thread-safe before libcurl initialization occurs.

The curl_version_info_data struct looks like this

typedef struct {
  CURLversion age;          /* see description below */

  const char *version;      /* human readable string */
  unsigned int version_num; /* numeric representation */
  const char *host;         /* human readable string */
  int features;             /* bitmask, see below */
  char *ssl_version;        /* human readable string */
  long ssl_version_num;     /* not used, always zero */
  const char *libz_version; /* human readable string */
  const char *const *protocols; /* protocols */

  /* when 'age' is CURLVERSION_SECOND or higher, the members below exist */
  const char *ares;         /* human readable string */
  int ares_num;             /* number */

  /* when 'age' is CURLVERSION_THIRD or higher, the members below exist */
  const char *libidn;       /* human readable string */

  /* when 'age' is CURLVERSION_FOURTH or higher (>= 7.16.1), the members
     below exist */
  int iconv_ver_num;       /* '_libiconv_version' if iconv support enabled */

  const char *libssh_version; /* human readable string */

  /* when 'age' is CURLVERSION_FIFTH or higher (>= 7.57.0), the members
     below exist */
  unsigned int brotli_ver_num; /* Numeric Brotli version
                                  (MAJOR << 24) | (MINOR << 12) | PATCH */
  const char *brotli_version; /* human readable string. */

  /* when 'age' is CURLVERSION_SIXTH or higher (>= 7.66.0), the members
     below exist */
  unsigned int nghttp2_ver_num; /* Numeric nghttp2 version
                                   (MAJOR << 16) | (MINOR << 8) | PATCH */
  const char *nghttp2_version; /* human readable string. */

  const char *quic_version;    /* human readable quic (+ HTTP/3) library +
                                  version or NULL */

  /* when 'age' is CURLVERSION_SEVENTH or higher (>= 7.70.0), the members
     below exist */
  const char *cainfo;          /* the built-in default CURLOPT_CAINFO, might
                                  be NULL */
  const char *capath;          /* the built-in default CURLOPT_CAPATH, might
                                  be NULL */
  /* when 'age' is CURLVERSION_EIGHTH or higher (>= 7.71.0), the members
     below exist */
  unsigned int zstd_ver_num; /* Numeric Zstd version
                                  (MAJOR << 24) | (MINOR << 12) | PATCH */
  const char *zstd_version; /* human readable string. */
  /* when 'age' is CURLVERSION_NINTH or higher (>= 7.75.0), the members
     below exist */
  const char *hyper_version; /* human readable string. */
  /* when 'age' is CURLVERSION_TENTH or higher (>= 7.77.0), the members
     below exist */
  const char *gsasl_version; /* human readable string. */
  /* when 'age' is CURLVERSION_ELEVENTH or higher (>= 7.87.0), the members
     below exist */
  const char *const *feature_names; /* Feature names. */
} curl_version_info_data;

age describes what the age of this struct is. The number depends on how new the libcurl you are using is. You are however guaranteed to get a struct that you have a matching struct for in the header, as you tell libcurl your "age" with the input argument.

version is just an ascii string for the libcurl version.

version_num is a 24 bit number created like this: <8 bits major number> | <8 bits minor number> | <8 bits patch number>. Version 7.9.8 is therefore returned as 0x070908.

host is an ascii string showing what host information that this libcurl was built for. As discovered by a configure script or set by the build environment.

features is a bit mask representing available features. It can have none, one or more bits set. The use of this field is deprecated: use feature_names instead. The feature names description below lists the associated bits.

feature_names is a pointer to an array of string pointers, containing the names of the features that libcurl supports. The array is terminated by a NULL entry. See the list of features names below.

ssl_version is an ASCII string for the TLS library name + version used. If libcurl has no SSL support, this is NULL. For example "Schannel", "Secure Transport" or "OpenSSL/1.1.0g".

ssl_version_num is always 0.

libz_version is an ASCII string (there is no numerical version). If libcurl has no libz support, this is NULL.

protocols is a pointer to an array of char * pointers, containing the names protocols that libcurl supports (using lowercase letters). The protocol names are the same as would be used in URLs. The array is terminated by a NULL entry.

FEATURES

alt-svc
    features mask bit: CURL_VERSION_ALTSVC

    HTTP Alt-Svc parsing and the associated options (Added in 7.64.1)

AsynchDNS
    features mask bit: CURL_VERSION_ASYNCHDNS

    libcurl was built with support for asynchronous name lookups, which allows more exact timeouts (even on Windows) and less blocking when using the multi interface. (added in 7.10.7)

brotli
    features mask bit: CURL_VERSION_BROTLI

    supports HTTP Brotli content encoding using libbrotlidec (Added in 7.57.0)

Debug
    features mask bit: CURL_VERSION_DEBUG

    libcurl was built with debug capabilities (added in 7.10.6)

gsasl
    features mask bit: CURL_VERSION_GSASL

    libcurl was built with libgsasl and thus with some extra SCRAM-SHA authentication methods. (added in 7.76.0)

GSS-API
    features mask bit: CURL_VERSION_GSSAPI

    libcurl was built with support for GSS-API. This makes libcurl use provided functions for Kerberos and SPNEGO authentication. It also allows libcurl to use the current user credentials without the app having to pass them on. (Added in 7.38.0)

HSTS
    features mask bit: CURL_VERSION_HSTS

    libcurl was built with support for HSTS (HTTP Strict Transport Security) (Added in 7.74.0)

HTTP2
    features mask bit: CURL_VERSION_HTTP2

    libcurl was built with support for HTTP2. (Added in 7.33.0)

HTTP3
    features mask bit: CURL_VERSION_HTTP3

    HTTP/3 and QUIC support are built-in (Added in 7.66.0)

HTTPS-proxy
    features mask bit: CURL_VERSION_HTTPS_PROXY

    libcurl was built with support for HTTPS-proxy. (Added in 7.52.0)

IDN features mask bit: CURL_VERSION_IDN

    libcurl was built with support for IDNA, domain names with international letters. (Added in 7.12.0)

IPv6
    features mask bit: CURL_VERSION_IPV6

    supports IPv6

Kerberos
    features mask bit: CURL_VERSION_KERBEROS5

    supports Kerberos V5 authentication for FTP, IMAP, LDAP, POP3, SMTP and SOCKSv5 proxy. (Added in 7.40.0)

Largefile
    features mask bit: CURL_VERSION_LARGEFILE

    libcurl was built with support for large files. (Added in 7.11.1)

libz
    features mask bit: CURL_VERSION_LIBZ

    supports HTTP deflate using libz (Added in 7.10)

MultiSSL
    features mask bit: CURL_VERSION_MULTI_SSL

    libcurl was built with multiple SSL backends. For details, see curl_global_sslset(3). (Added in 7.56.0)

NTLM
    features mask bit: CURL_VERSION_NTLM

    supports HTTP NTLM (added in 7.10.6)

NTLM_WB
    features mask bit: CURL_VERSION_NTLM_WB

    libcurl was built with support for NTLM delegation to a winbind helper. (Added in 7.22.0)

PSL features mask bit: CURL_VERSION_PSL

    libcurl was built with support for Mozilla's Public Suffix List. This makes libcurl ignore cookies with a domain that is on the list. (Added in 7.47.0)

SPNEGO
    features mask bit: CURL_VERSION_SPNEGO

    libcurl was built with support for SPNEGO authentication (Simple and Protected GSS-API Negotiation Mechanism, defined in RFC 2478.) (added in 7.10.8)

SSL features mask bit: CURL_VERSION_SSL

    supports SSL (HTTPS/FTPS) (Added in 7.10)

SSPI
    features mask bit: CURL_VERSION_SSPI

    libcurl was built with support for SSPI. This is only available on Windows and makes libcurl use Windows-provided functions for Kerberos, NTLM, SPNEGO and Digest authentication. It also allows libcurl to use the current user credentials without the app having to pass them on. (Added in 7.13.2)

threadsafe
    features mask bit: CURL_VERSION_THREADSAFE

    libcurl was built with thread-safety support (Atomic or SRWLOCK) to protect curl initialization. (Added in 7.84.0) See libcurl-thread(3)

TLS-SRP
    features mask bit: CURL_VERSION_TLSAUTH_SRP

    libcurl was built with support for TLS-SRP (in one or more of the built-in TLS backends). (Added in 7.21.4)

TrackMemory
    features mask bit: CURL_VERSION_CURLDEBUG

    libcurl was built with memory tracking debug capabilities. This is mainly of interest for libcurl hackers. (added in 7.19.6)

Unicode
    features mask bit: CURL_VERSION_UNICODE

    libcurl was built with Unicode support on Windows. This makes non-ASCII characters work in filenames and options passed to libcurl. (Added in 7.72.0)

UnixSockets
    features mask bit: CURL_VERSION_UNIX_SOCKETS

    libcurl was built with support for Unix domain sockets. (Added in 7.40.0)

zstd
    features mask bit: CURL_VERSION_ZSTD

    supports HTTP zstd content encoding using zstd library (Added in 7.72.0)

no name
    features mask bit: CURL_VERSION_CONV

    libcurl was built with support for character conversions, as provided by the CURLOPT_CONV_* callbacks. Always 0 since 7.82.0. (Added in 7.15.4, deprecated.)

no name
    features mask bit: CURL_VERSION_GSSNEGOTIATE

    supports HTTP GSS-Negotiate (added in 7.10.6, deprecated in 7.38.0)

no name
    features mask bit: CURL_VERSION_KERBEROS4

    supports Kerberos V4 (when using FTP). Legacy bit. Deprecated since 7.33.0.

PROTOCOLS
All

EXAMPLE
int main(void)
{
  curl_version_info_data *ver = curl_version_info(CURLVERSION_NOW);
  printf("libcurl version %u.%u.%u\n",
         (ver->version_num >> 16) & 0xff,
         (ver->version_num >> 8) & 0xff,
         ver->version_num & 0xff);
}

AVAILABILITY
Added in 7.10

RETURN VALUE
A pointer to a curl_version_info_data struct. curl_version(3)

SEE ALSO
curl_version(3)