89 lines
3.5 KiB
Groff
89 lines
3.5 KiB
Groff
.\" **************************************************************************
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.\" * _ _ ____ _
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.\" * Project ___| | | | _ \| |
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.\" * / __| | | | |_) | |
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.\" * | (__| |_| | _ <| |___
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.\" * \___|\___/|_| \_\_____|
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.\" *
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.\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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.\" *
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.\" * This software is licensed as described in the file COPYING, which
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.\" * you should have received as part of this distribution. The terms
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.\" * are also available at https://curl.se/docs/copyright.html.
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.\" *
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.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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.\" * copies of the Software, and permit persons to whom the Software is
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.\" * furnished to do so, under the terms of the COPYING file.
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.\" *
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.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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.\" * KIND, either express or implied.
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.\" *
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.\" * SPDX-License-Identifier: curl
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.\" *
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.\" **************************************************************************
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.\"
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.TH CURLOPT_ALTSVC_CTRL 3 "5 Feb 2019" libcurl libcurl
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.SH NAME
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CURLOPT_ALTSVC_CTRL \- control alt-svc behavior
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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#define CURLALTSVC_READONLYFILE (1<<2)
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#define CURLALTSVC_H1 (1<<3)
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#define CURLALTSVC_H2 (1<<4)
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#define CURLALTSVC_H3 (1<<5)
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC_CTRL, long bitmask);
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.fi
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.SH DESCRIPTION
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Populate the long \fIbitmask\fP with the correct set of features to instruct
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libcurl how to handle Alt-Svc for the transfers using this handle.
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libcurl only accepts Alt-Svc headers over a secure transport, meaning
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HTTPS. It also only completes a request to an alternative origin if that
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origin is properly hosted over HTTPS. These requirements are there to make
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sure both the source and the destination are legitimate.
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Alternative services are only used when setting up new connections. If there
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exists an existing connection to the host in the connection pool, then that is
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preferred.
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Setting any bit enables the alt-svc engine.
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.IP "CURLALTSVC_READONLYFILE"
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Do not write the alt-svc cache back to the file specified with
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\fICURLOPT_ALTSVC(3)\fP even if it gets updated. By default a file specified
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with that option is read and written to as deemed necessary.
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.IP "CURLALTSVC_H1"
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Accept alternative services offered over HTTP/1.1.
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.IP "CURLALTSVC_H2"
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Accept alternative services offered over HTTP/2. This is only used if libcurl
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was also built to actually support HTTP/2, otherwise this bit is ignored.
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.IP "CURLALTSVC_H3"
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Accept alternative services offered over HTTP/3. This is only used if libcurl
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was also built to actually support HTTP/3, otherwise this bit is ignored.
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.SH DEFAULT
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Alt-Svc handling is disabled by default. If \fICURLOPT_ALTSVC(3)\fP is set,
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\fICURLOPT_ALTSVC_CTRL(3)\fP has a default value corresponding to
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CURLALTSVC_H1 | CURLALTSVC_H2 | CURLALTSVC_H3 - the HTTP/2 and HTTP/3 bits are
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only set if libcurl was built with support for those versions.
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.SH PROTOCOLS
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HTTPS
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.SH EXAMPLE
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.nf
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CURL *curl = curl_easy_init();
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if(curl) {
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curl_easy_setopt(curl, CURLOPT_ALTSVC_CTRL, (long)CURLALTSVC_H1);
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curl_easy_setopt(curl, CURLOPT_ALTSVC, "altsvc-cache.txt");
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curl_easy_perform(curl);
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}
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.fi
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.SH AVAILABILITY
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Added in 7.64.1
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.SH RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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.SH "SEE ALSO"
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.BR CURLOPT_ALTSVC (3),
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.BR CURLOPT_CONNECT_TO (3),
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.BR CURLOPT_RESOLVE (3)
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