curl / libcurl / API / curl_easy_setopt / CURLOPT_SSL_ENABLE_NPN

CURLOPT_SSL_ENABLE_NPN explained

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 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);
  }
}

Deprecated

Deprecated since 7.86.0.

Availability

Added in curl 7.36.0

Return value

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