NAME

       CURLOPT_SSL_ENABLE_ALPN - Application Layer Protocol Negotiation

SYNOPSIS

       #include <curl/curl.h>

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

DESCRIPTION

       Pass  a  long  as parameter, 0 or 1 where 1 is for enable and 0 for disable. This option enables/disables
       ALPN 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

       HTTP

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_ALPN, 0L);
           res = curl_easy_perform(curl);
           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY

       Added in 7.36.0

RETURN VALUE

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

SEE ALSO

       CURLOPT_SSL_ENABLE_NPN(3), CURLOPT_SSL_OPTIONS(3)