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SSL_set_bio.3ossl - Man Page

connect the SSL object with a BIO


 #include <openssl/ssl.h>

 void SSL_set_bio(SSL *ssl, BIO *rbio, BIO *wbio);
 void SSL_set0_rbio(SSL *s, BIO *rbio);
 void SSL_set0_wbio(SSL *s, BIO *wbio);


SSL_set0_rbio() connects the BIO rbio for the read operations of the ssl object. The SSL engine inherits the behaviour of rbio. If the BIO is nonblocking then the ssl object will also have nonblocking behaviour. This function transfers ownership of rbio to ssl. It will be automatically freed using BIO_free_all(3) when the ssl is freed. On calling this function, any existing rbio that was previously set will also be freed via a call to BIO_free_all(3) (this includes the case where the rbio is set to the same value as previously).

SSL_set0_wbio() works in the same as SSL_set0_rbio() except that it connects the BIO wbio for the write operations of the ssl object. Note that if the rbio and wbio are the same then SSL_set0_rbio() and SSL_set0_wbio() each take ownership of one reference. Therefore, it may be necessary to increment the number of references available using BIO_up_ref(3) before calling the set0 functions.

SSL_set_bio() is similar to SSL_set0_rbio() and SSL_set0_wbio() except that it connects both the rbio and the wbio at the same time, and transfers the ownership of rbio and wbio to ssl according to the following set of rules:

Because of this complexity, this function should be avoided; use SSL_set0_rbio() and SSL_set0_wbio() instead.

Where a new BIO is set on a QUIC connection SSL object, blocking mode will be disabled on that SSL object if the BIO cannot support blocking mode. If another BIO is subsequently set on the SSL object which can support blocking mode, blocking mode will not be automatically re-enabled. For more information, see SSL_set_blocking_mode(3).

Return Values

SSL_set_bio(), SSL_set0_rbio() and SSL_set0_wbio() cannot fail.

See Also

SSL_get_rbio(3), SSL_connect(3), SSL_accept(3), SSL_shutdown(3), ssl(7), bio(7)


SSL_set0_rbio() and SSL_set0_wbio() were added in OpenSSL 1.1.0.

Referenced By

BIO_s_bio.3ossl(3), openssl-quic.7ossl(7), ossl-guide-tls-client-block.7ossl(7), SSL_get_rbio.3ossl(3), SSL_set_fd.3ossl(3).

The man pages SSL_set0_rbio.3ossl(3) and SSL_set0_wbio.3ossl(3) are aliases of SSL_set_bio.3ossl(3).

2024-07-09 3.2.2 OpenSSL