.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2021, Daniel Stenberg, , et al. .\" * .\" * This software is licensed as described in the file COPYING, which .\" * you should have received as part of this distribution. The terms .\" * are also available at https://curl.se/docs/copyright.html. .\" * .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell .\" * copies of the Software, and permit persons to whom the Software is .\" * furnished to do so, under the terms of the COPYING file. .\" * .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY .\" * KIND, either express or implied. .\" * .\" ************************************************************************** .TH curl_global_sslset 3 "15 July 2017" "libcurl 7.56" "libcurl Manual" .SH NAME curl_global_sslset - Select SSL backend to use with libcurl .SH SYNOPSIS .nf #include typedef struct { curl_sslbackend id; const char *name; } curl_ssl_backend; typedef enum { CURLSSLBACKEND_NONE = 0, CURLSSLBACKEND_OPENSSL = 1, CURLSSLBACKEND_GNUTLS = 2, CURLSSLBACKEND_NSS = 3, CURLSSLBACKEND_GSKIT = 5, CURLSSLBACKEND_POLARSSL = 6, /* deprecated */ CURLSSLBACKEND_WOLFSSL = 7, CURLSSLBACKEND_SCHANNEL = 8, CURLSSLBACKEND_SECURETRANSPORT = 9, CURLSSLBACKEND_AXTLS = 10, /* deprecated */ CURLSSLBACKEND_MBEDTLS = 11, CURLSSLBACKEND_MESALINK = 12, CURLSSLBACKEND_BEARSSL = 13 } curl_sslbackend; CURLsslset curl_global_sslset(curl_sslbackend id, const char *name, curl_ssl_backend ***avail); .fi .SH DESCRIPTION This function configures at runtime which SSL backend to use with libcurl. This function can only be used to select an SSL backend once, and it must be called \fBbefore\fP \fIcurl_global_init(3)\fP. The backend can be identified by the \fIid\fP (e.g. \fBCURLSSLBACKEND_OPENSSL\fP). The backend can also be specified via the \fIname\fP parameter for a case insensitive match (passing -1 as \fIid\fP). If both \fIid\fP and \fIname\fP are specified, the \fIname\fP will be ignored. If neither \fIid\fP nor \fPname\fP are specified, the function will fail with CURLSSLSET_UNKNOWN_BACKEND and set the \fIavail\fP pointer to the NULL-terminated list of available backends. The available backends are those that this particular build of libcurl supports. Since libcurl 7.60.0, the \fIavail\fP pointer will always be set to the list of alternatives if non-NULL. Upon success, the function returns CURLSSLSET_OK. If the specified SSL backend is not available, the function returns CURLSSLSET_UNKNOWN_BACKEND and sets the \fIavail\fP pointer to a NULL-terminated list of available SSL backends. In this case, you may call the function again to try to select a different backend. The SSL backend can be set only once. If it has already been set, a subsequent attempt to change it will result in a \fBCURLSSLSET_TOO_LATE\fP. \fBThis function is not thread safe.\fP You must not call it when any other thread in the program (i.e. a thread sharing the same memory) is running. This does not just mean no other thread that is using libcurl. .SH EXAMPLE .nf /* choose a specific backend */ curl_global_sslset(CURLSSLBACKEND_WOLFSSL, NULL, NULL); /* list the available ones */ const curl_ssl_backend **list; curl_global_sslset((curl_sslbackend)-1, NULL, &list); for(i = 0; list[i]; i++) printf("SSL backend #%d: '%s' (ID: %d)\\n", i, list[i]->name, list[i]->id); .fi .SH AVAILABILITY This function was added in libcurl 7.56.0. Before this version, there was no support for choosing SSL backends at runtime. .SH RETURN VALUE If this function returns CURLSSLSET_OK, the backend was successfully selected. If the chosen backend is unknown (or support for the chosen backend has not been compiled into libcurl), the function returns \fICURLSSLSET_UNKNOWN_BACKEND\fP. If the backend had been configured previously, or if \fIcurl_global_init(3)\fP has already been called, the function returns \fICURLSSLSET_TOO_LATE\fP. If this libcurl was built completely without SSL support, with no backends at all, this function returns \fICURLSSLSET_NO_BACKENDS\fP. .SH "SEE ALSO" .BR curl_global_init "(3), " .BR libcurl "(3) "