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e3fe020089
Remove the PROTOCOLS section from the source files completely and instead generate them based on the header data in the curldown files. It also generates TLS backend information for options marked for TLS as protocol. Closes #13175
96 lines
2.5 KiB
Markdown
96 lines
2.5 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_ALTSVC_CTRL
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_ALTSVC (3)
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- CURLOPT_CONNECT_TO (3)
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- CURLOPT_RESOLVE (3)
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Protocol:
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- HTTP
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---
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# NAME
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CURLOPT_ALTSVC_CTRL - control alt-svc behavior
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# SYNOPSIS
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~~~c
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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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~~~
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# DESCRIPTION
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Populate the long *bitmask* 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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## CURLALTSVC_READONLYFILE
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Do not write the alt-svc cache back to the file specified with
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CURLOPT_ALTSVC(3) 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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## CURLALTSVC_H1
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Accept alternative services offered over HTTP/1.1.
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## 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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## 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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# DEFAULT
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Alt-Svc handling is disabled by default. If CURLOPT_ALTSVC(3) is set,
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CURLOPT_ALTSVC_CTRL(3) 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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# EXAMPLE
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~~~c
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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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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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}
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~~~
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# AVAILABILITY
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Added in 7.64.1
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# RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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