SSL_get_fd.3ossl - Man Page

 #include <openssl/ssl.h>

 int SSL_get_fd(const SSL *ssl);
 int SSL_get_rfd(const SSL *ssl);
 int SSL_get_wfd(const SSL *ssl);

SSL_get_fd() returns the file descriptor which is linked to ssl. SSL_get_rfd() and SSL_get_wfd() return the file descriptors for the read or the write channel, which can be different. If the read and the write channel are different, SSL_get_fd() will return the file descriptor of the read channel.

The following return values can occur:

-1

The operation failed, because the underlying BIO is not of the correct type (suitable for file descriptors).

>=0

The file descriptor linked to ssl.

SSL_set_fd(3), ssl(7) , bio(7)

Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance with the License.  You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

SSL_set_fd.3ossl(3).

The man pages SSL_get_rfd.3ossl(3) and SSL_get_wfd.3ossl(3) are aliases of SSL_get_fd.3ossl(3).