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
communication channel must already have been set and assigned to the ssl by setting an
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, indicating the
problem by the return value -1. 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 continue.
The following return values can occur:
0 The TLS/SSL handshake was not successful but was shut down controlled and by the
specifications of the TLS/SSL protocol. Call SSL_get_error() with the return value ret
to find out the reason.
1 The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been
<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), openssl_bio(3),
SSL_set_connect_state(3), SSL_do_handshake(3), SSL_CTX_new(3)
1.0.1i 2014-06-05 SSL_accept(3)