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 object by setting an underlying
BIO.
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.
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(3) 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(2) 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:
- 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(3) with the return value ret to find out the reason.
- 1
- The TLS/SSL handshake was successfully completed, and a TLS/SSL connection has been established.
- <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(3) with the return value ret to find out the reason.
SEE ALSO
BIO_new(3), ssl(3), SSL_connect(3), SSL_CTX_new(3), SSL_do_handshake(3), SSL_get_error(3), SSL_set_connect_state(3), SSL_shutdown(3)
HISTORY
SSL_accept() appeared in SSLeay 0.4 or
earlier and has been available since OpenBSD
2.4.