NAME

       SSL_set_fd, SSL_set_rfd, SSL_set_wfd - connect the SSL object with a file descriptor

SYNOPSIS

        #include <openssl/ssl.h>

        int SSL_set_fd(SSL *ssl, int fd);
        int SSL_set_rfd(SSL *ssl, int fd);
        int SSL_set_wfd(SSL *ssl, int fd);

DESCRIPTION

       SSL_set_fd() sets the file descriptor fd as the input/output facility for the TLS/SSL (encrypted) side of
       ssl. fd will typically be the socket file descriptor of a network connection.

       When performing the operation, a socket BIO is automatically created to interface between the ssl and fd.
       The BIO and hence the SSL engine inherit the behaviour of fd. If fd is nonblocking, the ssl will also
       have nonblocking behaviour.

       If there was already a BIO connected to ssl, BIO_free() will be called (for both the reading and writing
       side, if different).

       SSL_set_rfd() and SSL_set_wfd() perform the respective action, but only for the read channel or the write
       channel, which can be set independently.

RETURN VALUES

       The following return values can occur:

       0   The operation failed. Check the error stack to find out why.

       1   The operation succeeded.

NOTES

       On Windows, a socket handle is a 64-bit data type (UINT_PTR), which leads to a compiler warning
       (conversion from 'SOCKET' to 'int', possible loss of data) when passing the socket handle to
       SSL_set_*fd(). For the time being, this warning can safely be ignored, because although the Microsoft
       documentation claims that the upper limit is INVALID_SOCKET-1 (2^64 - 2), in practice the current
       socket() implementation returns an index into the kernel handle table, the size of which is limited to
       2^24.

SEE ALSO

       SSL_get_fd(3), SSL_set_bio(3), SSL_connect(3), SSL_accept(3), SSL_shutdown(3), ssl(7) , bio(7)

COPYRIGHT

       Copyright 2000-2021 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>.