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.TH CURLOPT_SSL_ENABLE_ALPN 3 "September 26, 2023" "ibcurl 8.4.0" libcurl

.SH NAME
CURLOPT_SSL_ENABLE_ALPN \- Application Layer Protocol Negotiation
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_ENABLE_ALPN, long npn);
.fi
.SH 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.
.SH DEFAULT
1, enabled
.SH PROTOCOLS
HTTP
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
  curl_easy_setopt(curl, CURLOPT_SSL_ENABLE_ALPN, 0L);
  ret = curl_easy_perform(curl);
  curl_easy_cleanup(curl);
}
.fi
.SH AVAILABILITY
Added in 7.36.0
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_SSL_ENABLE_NPN (3),
.BR CURLOPT_SSL_OPTIONS (3)