SSL_accept(3) OpenSSL SSL_accept(3)
SSL_accept - wait for a TLS/SSL client to initiate a TLS/SSL handshake
int SSL_accept(SSL *ssl);
SSL_accept() waits for a TLS/SSL client to initiate the TLS/SSL handshake. The communica-
tion channel must already have been set and assigned to the ssl by setting an underlying
The behaviour of SSL_accept() depends on the underlying BIO.
If the underlying BIO is blocking, SSL_accept() will only return once the handshake has
been finished or an error occurred, except for SGC (Server Gated Cryptography). For SGC,
SSL_accept() may return with -1, but SSL_get_error() will yield SSL_ERROR_WANT_READ/WRITE
and SSL_accept() should be called again.
If the underlying BIO is non-blocking, SSL_accept() will also return when the underlying
BIO could not satisfy the needs of SSL_accept() to continue the handshake. In this case a
call to SSL_get_error() with the return value of SSL_accept() will yield
SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE. The calling process then must repeat the call
after taking appropriate action to satisfy the needs of SSL_accept(). The action depends
on the underlying BIO. When using a non-blocking socket, nothing is to be done, but
select() can be used to check for the required condition. When using a buffering BIO, like
a BIO pair, data must be written into or retrieved out of the BIO before being able to
The following return values can occur:
1 The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been estab-
0 The TLS/SSL handshake was not successful but was shut down controlled and by the spec-
ifications of the TLS/SSL protocol. Call SSL_get_error() with the return value ret to
find out the reason.
<0 The TLS/SSL handshake was not successful because a fatal error occurred either at the
protocol level or a connection failure occurred. The shutdown was not clean. It can
also occur of action is need to continue the operation for non-blocking BIOs. Call
SSL_get_error() with the return value ret to find out the reason.
SSL_get_error(3), SSL_connect(3), SSL_shutdown(3), ssl(3), bio(3), SSL_set_con-
nect_state(3), SSL_do_handshake(3), SSL_CTX_new(3)
0.9.7a 2002-07-19 SSL_accept(3)