139 lines
4.2 KiB
Markdown
139 lines
4.2 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: curl_global_sslset
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Section: 3
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Source: libcurl
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See-also:
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- curl_global_init (3)
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- libcurl (3)
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---
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# NAME
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curl_global_sslset - Select SSL backend to use with libcurl
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# SYNOPSIS
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~~~c
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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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~~~
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# 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 **before** curl_global_init(3).
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The backend can be identified by the *id*
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(e.g. **CURLSSLBACKEND_OPENSSL**). The backend can also be specified via the
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*name* parameter for a case insensitive match (passing
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**CURLSSLBACKEND_NONE** as *id*). If both *id* and *name* are
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specified, the *name* is ignored.
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If neither *id* nor *name* are specified, the function fails with
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**CURLSSLSET_UNKNOWN_BACKEND** and set the *avail* 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 *avail* 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 **CURLSSLSET_OK**.
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If the specified SSL backend is not available, the function returns
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**CURLSSLSET_UNKNOWN_BACKEND** and sets the *avail* 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 **CURLSSLSET_TOO_LATE** getting returned.
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This function is thread-safe since libcurl 7.84.0 if
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curl_version_info(3) 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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# 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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curl_global_sslset(3) they are all just "OpenSSL". They all mostly
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provide the same API.
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curl_version_info(3) can return more specific info about the exact
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OpenSSL flavor and version number is use.
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# struct
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~~~c
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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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~~~
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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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int i;
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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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}
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~~~
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# 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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# RETURN VALUE
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If this function returns *CURLSSLSET_OK*, 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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*CURLSSLSET_UNKNOWN_BACKEND*.
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If the backend had been configured previously, or if curl_global_init(3)
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has already been called, the function returns *CURLSSLSET_TOO_LATE*.
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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 *CURLSSLSET_NO_BACKENDS*.
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