SSL_set_fd.3ssl - Man Page

connect the SSL object with a file descriptor


 #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);


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:


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


The operation succeeded.

See Also

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

Referenced By

ssl.7ssl(7), SSL_get_fd.3ssl(3).

The man pages SSL_set_rfd.3ssl(3) and SSL_set_wfd.3ssl(3) are aliases of SSL_set_fd.3ssl(3).

2021-03-26 1.1.1k OpenSSL