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 since 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
This functionality affects 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 result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_SSL_ENABLE_NPN, 1L);
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

DEPRECATED
Deprecated since 7.86.0

AVAILABILITY
Added in curl 7.36.0

RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO
CURLOPT_SSL_ENABLE_ALPN(3), CURLOPT_SSL_OPTIONS(3)