136 lines
5.2 KiB
Groff
136 lines
5.2 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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.TH curl_global_sslset 3 "15 July 2017" "libcurl" "libcurl"
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.SH NAME
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curl_global_sslset - Select SSL backend to use with libcurl
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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CURLsslset curl_global_sslset(curl_sslbackend id,
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const char *name,
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const curl_ssl_backend ***avail);
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.fi
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.SH DESCRIPTION
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This function configures at runtime which SSL backend to use with
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libcurl. This function can only be used to select an SSL backend once, and it
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must be called \fBbefore\fP \fIcurl_global_init(3)\fP.
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The backend can be identified by the \fIid\fP
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(e.g. \fBCURLSSLBACKEND_OPENSSL\fP). The backend can also be specified via the
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\fIname\fP parameter for a case insensitive match (passing
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\fBCURLSSLBACKEND_NONE\fP as \fIid\fP). If both \fIid\fP and \fIname\fP are
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specified, the \fIname\fP is ignored.
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If neither \fIid\fP nor \fPname\fP are specified, the function fails with
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\fBCURLSSLSET_UNKNOWN_BACKEND\fP and set the \fIavail\fP pointer to the
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NULL-terminated list of available backends. The available backends are those
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that this particular build of libcurl supports.
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Since libcurl 7.60.0, the \fIavail\fP pointer is always set to the list of
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alternatives if non-NULL.
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Upon success, the function returns \fBCURLSSLSET_OK\fP.
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If the specified SSL backend is not available, the function returns
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\fBCURLSSLSET_UNKNOWN_BACKEND\fP and sets the \fIavail\fP pointer to a
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NULL-terminated list of available SSL backends. In this case, you may call the
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function again to try to select a different backend.
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The SSL backend can be set only once. If it has already been set, a subsequent
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attempt to change it results in a \fBCURLSSLSET_TOO_LATE\fP getting returned.
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This function is thread-safe since libcurl 7.84.0 if
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\fIcurl_version_info(3)\fP has the CURL_VERSION_THREADSAFE feature bit set
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(most platforms).
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If this is not thread-safe, you must not call this function when any other
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thread in the program (i.e. a thread sharing the same memory) is running.
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This does not just mean no other thread that is using libcurl.
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.SH OpenSSL
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The name "OpenSSL" is used for all versions of OpenSSL and its associated
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forks/flavors in this function. OpenSSL, BoringSSL, libressl, quictls and
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AmiSSL are all supported by libcurl, but in the eyes of
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\fIcurl_global_sslset(3)\fP they are all just "OpenSSL". They all mostly
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provide the same API.
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\fIcurl_version_info(3)\fP can return more specific info about the exact
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OpenSSL flavor and version number is use.
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.SH struct
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.nf
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typedef struct {
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curl_sslbackend id;
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const char *name;
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} curl_ssl_backend;
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typedef enum {
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CURLSSLBACKEND_NONE = 0,
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CURLSSLBACKEND_OPENSSL = 1, /* or one of its forks */
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CURLSSLBACKEND_GNUTLS = 2,
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CURLSSLBACKEND_NSS = 3,
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CURLSSLBACKEND_GSKIT = 5, /* deprecated */
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CURLSSLBACKEND_POLARSSL = 6, /* deprecated */
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CURLSSLBACKEND_WOLFSSL = 7,
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CURLSSLBACKEND_SCHANNEL = 8,
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CURLSSLBACKEND_SECURETRANSPORT = 9,
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CURLSSLBACKEND_AXTLS = 10, /* deprecated */
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CURLSSLBACKEND_MBEDTLS = 11,
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CURLSSLBACKEND_MESALINK = 12, /* deprecated */
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CURLSSLBACKEND_BEARSSL = 13,
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CURLSSLBACKEND_RUSTLS = 14
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} curl_sslbackend;
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.fi
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.SH EXAMPLE
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.nf
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/* choose a specific backend */
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curl_global_sslset(CURLSSLBACKEND_WOLFSSL, NULL, NULL);
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/* list the available ones */
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const curl_ssl_backend **list;
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curl_global_sslset(CURLSSLBACKEND_NONE, NULL, &list);
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for(i = 0; list[i]; i++)
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printf("SSL backend #%d: '%s' (ID: %d)\\n",
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i, list[i]->name, list[i]->id);
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.fi
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.SH AVAILABILITY
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This function was added in libcurl 7.56.0. Before this version, there was no
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support for choosing SSL backends at runtime.
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.SH RETURN VALUE
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If this function returns \fICURLSSLSET_OK\fP, the backend was successfully
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selected.
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If the chosen backend is unknown (or support for the chosen backend has not
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been compiled into libcurl), the function returns
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\fICURLSSLSET_UNKNOWN_BACKEND\fP.
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If the backend had been configured previously, or if \fIcurl_global_init(3)\fP
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has already been called, the function returns \fICURLSSLSET_TOO_LATE\fP.
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If this libcurl was built completely without SSL support, with no backends at
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all, this function returns \fICURLSSLSET_NO_BACKENDS\fP.
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.SH "SEE ALSO"
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.BR curl_global_init (3),
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.BR libcurl (3)
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