CURLOPT_SSL_ENABLE_NPN(3)  Library Functions Manual  CURLOPT_SSL_ENABLE_NPN(3)

NAME
       CURLOPT_SSL_ENABLE_NPN - use NPN

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_ENABLE_NPN, long npn);

DESCRIPTION
       Deprecated in 7.86.0. Setting this option has no function.

       Pass a long as parameter, 0 or 1 where 1 is for enable and 0 for
       disable. This option enables/disables NPN in the SSL handshake (if the
       SSL backend libcurl is built to use supports it), which can be used to
       negotiate http2.

DEFAULT
       1, enabled

PROTOCOLS
       All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

       All TLS backends support this option.

EXAMPLE
       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
           curl_easy_setopt(curl, CURLOPT_SSL_ENABLE_NPN, 1L);
           res = curl_easy_perform(curl);
           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY
       Added in 7.36.0. Deprecated in 7.86.0.

RETURN VALUE
       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
       if not.

SEE ALSO
       CURLOPT_SSL_ENABLE_ALPN(3), CURLOPT_SSL_OPTIONS(3)

libcurl                          April 26 2024       CURLOPT_SSL_ENABLE_NPN(3)