SSL_accept(3)SSL_accept(3)NAMESSL_accept - Wait for a TLS/SSL client to initiate a TLS/SSL handshake
SYNOPSIS
#include <openssl/ssl.h>
int SSL_accept(
SSL *ssl );
DESCRIPTION
The SSL_accept() function 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 underlying BIO.
NOTES
The behavior of the SSL_accept() function depends on the underlying
BIO.
If the underlying BIO is blocking, the SSL_accept() function will only
return once the handshake has been finished or an error occurred,
except for Server Gated Cryptography (SGC). For SGC, the SSL_accept()
function might return with -1, but the SSL_get_error() function will
yield SSL_ERROR_WANT_READ/WRITE and SSL_accept() should be called
again.
If the underlying BIO is non-blocking, the SSL_accept() function will
also return when the underlying BIO could not satisfy the needs of the
SSL_accept() function to continue the handshake. In this case a call to
the SSL_get_error() function 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 the
select() function 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.
RETURN VALUES
The following return values can occur: The TLS/SSL handshake was suc‐
cessfully completed, a TLS/SSL connection has been established. 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 the reason. The TLS/SSL handshake
was not successful because a fatal error occurred either at the proto‐
col level or a connection failure occurred. The shutdown was not clean.
It can also occur if action is needed to continue the operation for
non-blocking BIOs. Call the SSL_get_error() function with the return
value ret to find the reason.
SEE ALSO
Functions: SSL_get_error(3), SSL_connect(3), SSL_shutdown(3), ssl(3),
bio(3), SSL_set_connect_state(3), SSL_do_handshake(3), SSL_CTX_new(3)SSL_accept(3)
