5 SSL_connect - initiate the TLS/SSL handshake with an TLS/SSL server
9 #include <openssl/ssl.h>
11 int SSL_connect(SSL *ssl);
15 SSL_connect() initiates the TLS/SSL handshake with a server. The communication
16 channel must already have been set and assigned to the B<ssl> by setting an
21 The behaviour of SSL_connect() depends on the underlying BIO.
23 If the underlying BIO is B<blocking>, SSL_connect() will only return once the
24 handshake has been finished or an error occurred.
26 If the underlying BIO is B<non-blocking>, SSL_connect() will also return
27 when the underlying BIO could not satisfy the needs of SSL_connect()
28 to continue the handshake, indicating the problem by the return value -1.
29 In this case a call to SSL_get_error() with the
30 return value of SSL_connect() will yield B<SSL_ERROR_WANT_READ> or
31 B<SSL_ERROR_WANT_WRITE>. The calling process then must repeat the call after
32 taking appropriate action to satisfy the needs of SSL_connect().
33 The action depends on the underlying BIO. When using a non-blocking socket,
34 nothing is to be done, but select() can be used to check for the required
35 condition. When using a buffering BIO, like a BIO pair, data must be written
36 into or retrieved out of the BIO before being able to continue.
40 The following return values can occur:
46 The TLS/SSL handshake was not successful but was shut down controlled and
47 by the specifications of the TLS/SSL protocol. Call SSL_get_error() with the
48 return value B<ret> to find out the reason.
52 The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been
57 The TLS/SSL handshake was not successful, because a fatal error occurred either
58 at the protocol level or a connection failure occurred. The shutdown was
59 not clean. It can also occur of action is need to continue the operation
60 for non-blocking BIOs. Call SSL_get_error() with the return value B<ret>
61 to find out the reason.
67 L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_accept(3)|SSL_accept(3)>,
68 L<SSL_shutdown(3)|SSL_shutdown(3)>, L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>,
69 L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
70 L<SSL_do_handshake(3)|SSL_do_handshake(3)>,
71 L<SSL_CTX_new(3)|SSL_CTX_new(3)>