SSL_do_handshake (3)

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NAME

SSL_do_handshake - perform a TLS/SSL handshake

SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_do_handshake(SSL *ssl);

DESCRIPTION

SSL_do_handshake() will wait for a handshake to take place. If the connection is in client mode, the handshake will be started. The handshake routines may have to be explicitly set in advance using either SSL_set_connect_state(3) or SSL_set_accept_state(3).

NOTES

The behaviour of SSL_do_handshake() depends on the underlying

If the underlying

is blocking, SSL_do_handshake() will only return once the handshake has been finished or an error occurred.

If the underlying

is non-blocking, SSL_do_handshake() will also return when the underlying could not satisfy the needs of SSL_do_handshake() to continue the handshake. In this case a call to SSL_get_error() with the return value of SSL_do_handshake() will yield or . The calling process then must repeat the call after taking appropriate action to satisfy the needs of SSL_do_handshake(). The action depends on the underlying 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 like a pair, data must be written into or retrieved out of the 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() with the return value ret to find out the reason.

1

The

TLS/SSL

handshake was successfully completed, 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() with the return value ret to find out the reason.

SEE ALSO

SSL_get_error(3), SSL_connect(3), SSL_accept(3), ssl(3), bio(3), SSL_set_connect_state(3)