Annotation of embedaddon/curl/docs/libcurl/opts/CURLOPT_ALTSVC_CTRL.3, revision 1.1.1.1
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23: .TH CURLOPT_ALTSVC_CTRL 3 "February 11, 2020" "libcurl 7.70.0" "curl_easy_setopt options"
24:
25: .SH NAME
26: CURLOPT_ALTSVC_CTRL \- control alt-svc behavior
27: .SH SYNOPSIS
28: .nf
29: #include <curl/curl.h>
30:
31: #define CURLALTSVC_IMMEDIATELY (1<<0)
32: #define CURLALTSVC_READONLYFILE (1<<2)
33: #define CURLALTSVC_H1 (1<<3)
34: #define CURLALTSVC_H2 (1<<4)
35: #define CURLALTSVC_H3 (1<<5)
36:
37: CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC_CTRL, long bitmask);
38: .fi
39: .SH EXPERIMENTAL
40: Warning: this feature is early code and is marked as experimental. It can only
41: be enabled by explicitly telling configure with \fB--enable-alt-svc\fP. You are
42: advised to not ship this in production before the experimental label is
43: removed.
44: .SH DESCRIPTION
45: Populate the long \fIbitmask\fP with the correct set of features to instruct
46: libcurl how to handle Alt-Svc for the transfers using this handle.
47:
48: libcurl will only accept Alt-Svc headers over a secure transport, meaning
49: HTTPS. It will also only complete a request to an alternative origin if that
50: origin is properly hosted over HTTPS. These requirements are there to make
51: sure both the source and the destination are legitimate.
52:
53: Setting any bit will enable the alt-svc engine.
54: .IP "CURLALTSVC_IMMEDIATELY"
55: If an Alt-Svc: header is received, this instructs libcurl to switch to one of
56: those alternatives asap rather than to save it and use for the next
57: request. (Not currently supported).
58: .IP "CURLALTSVC_READONLYFILE"
59: Do not write the alt-svc cache back to the file specified with
60: \fICURLOPT_ALTSVC(3)\fP even if it gets updated. By default a file specified
61: with that option will be read and written to as deemed necessary.
62: .IP "CURLALTSVC_H1"
63: Accept alternative services offered over HTTP/1.1.
64: .IP "CURLALTSVC_H2"
65: Accept alternative services offered over HTTP/2. This will only be used if
66: libcurl was also built to actually support HTTP/2, otherwise this bit will be
67: ignored.
68: .IP "CURLALTSVC_H3"
69: Accept alternative services offered over HTTP/3. This will only be used if
70: libcurl was also built to actually support HTTP/3, otherwise this bit will be
71: ignored.
72: .SH DEFAULT
73: Alt-Svc handling is disabled by default. If \fICURLOPT_ALTSVC(3)\fP is set,
74: \fICURLOPT_ALTSVC_CTRL(3)\fP has a default value corresponding to
75: CURLALTSVC_H1 | CURLALTSVC_H2 | CURLALTSVC_H3 - the HTTP/2 and HTTP/3 bits are
76: only set if libcurl was built with support for those versions.
77: .SH PROTOCOLS
78: HTTPS
79: .SH EXAMPLE
80: .nf
81: CURL *curl = curl_easy_init();
82: if(curl) {
83: curl_easy_setopt(curl, CURLOPT_ALTSVC_CTRL, CURLALTSVC_H1);
84: curl_easy_setopt(curl, CURLOPT_ALTSVC, "altsvc-cache.txt");
85: curl_easy_perform(curl);
86: }
87: .fi
88: .SH AVAILABILITY
89: Added in 7.64.1
90: .SH RETURN VALUE
91: Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
92: .SH "SEE ALSO"
93: .BR CURLOPT_ALTSVC "(3), " CURLOPT_CONNECT_TO "(3), " CURLOPT_RESOLVE "(3), "
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