45 lines
1.3 KiB
Groff
45 lines
1.3 KiB
Groff
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.\" generated by cd2nroff 0.1 from CURLOPT_SSL_ENABLE_ALPN.md
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.TH CURLOPT_SSL_ENABLE_ALPN 3 "2025-07-07" libcurl
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.SH NAME
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CURLOPT_SSL_ENABLE_ALPN \- Application Layer Protocol Negotiation
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_ENABLE_ALPN, long npn);
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.fi
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.SH DESCRIPTION
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Pass a long as parameter, 0 or 1 where 1 is for enable and 0 for disable. This
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option enables/disables ALPN in the SSL handshake (if the SSL backend libcurl
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is built to use supports it), which can be used to negotiate http2.
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.SH DEFAULT
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1, enabled
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.SH PROTOCOLS
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This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
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All TLS backends support this option.
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.SH EXAMPLE
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.nf
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int main(void)
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{
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CURL *curl = curl_easy_init();
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if(curl) {
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CURLcode res;
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curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
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curl_easy_setopt(curl, CURLOPT_SSL_ENABLE_ALPN, 0L);
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res = curl_easy_perform(curl);
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curl_easy_cleanup(curl);
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}
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}
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.fi
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.SH AVAILABILITY
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Added in curl 7.36.0
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.SH RETURN VALUE
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\fIcurl_easy_setopt(3)\fP returns a CURLcode indicating success or error.
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CURLE_OK (0) means everything was OK, non\-zero means an error occurred, see
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\fIlibcurl\-errors(3)\fP.
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.SH SEE ALSO
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.BR CURLOPT_SSL_ENABLE_NPN (3),
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.BR CURLOPT_SSL_OPTIONS (3)
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