NAME¶
SSL_accept - wait for a TLS/SSL client to initiate a TLS/SSL handshake
SYNOPSIS¶
#include <openssl/ssl.h>
int SSL_accept(SSL *ssl);
DESCRIPTION¶
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 underlying
BIO.
NOTES¶
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.
RETURN VALUES¶
The following return values can occur:
- 1.
- The TLS/SSL handshake was successfully completed, a TLS/SSL
connection has been established.
- 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.
- <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.
SEE ALSO¶
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)