1=pod 2 3=head1 NAME 4 5SSL_connect - initiate the TLS/SSL handshake with an TLS/SSL server 6 7=head1 SYNOPSIS 8 9 #include <openssl/ssl.h> 10 11 int SSL_connect(SSL *ssl); 12 13=head1 DESCRIPTION 14 15SSL_connect() initiates the TLS/SSL handshake with a server. The communication 16channel must already have been set and assigned to the B<ssl> by setting an 17underlying B<BIO>. 18 19=head1 NOTES 20 21The behaviour of SSL_connect() depends on the underlying BIO. 22 23If the underlying BIO is B<blocking>, SSL_connect() will only return once the 24handshake has been finished or an error occurred. 25 26If the underlying BIO is B<non-blocking>, SSL_connect() will also return 27when the underlying BIO could not satisfy the needs of SSL_connect() 28to continue the handshake, indicating the problem by the return value -1. 29In this case a call to SSL_get_error() with the 30return value of SSL_connect() will yield B<SSL_ERROR_WANT_READ> or 31B<SSL_ERROR_WANT_WRITE>. The calling process then must repeat the call after 32taking appropriate action to satisfy the needs of SSL_connect(). 33The action depends on the underlying BIO. When using a non-blocking socket, 34nothing is to be done, but select() can be used to check for the required 35condition. When using a buffering BIO, like a BIO pair, data must be written 36into or retrieved out of the BIO before being able to continue. 37 38=head1 RETURN VALUES 39 40The following return values can occur: 41 42=over 4 43 44=item Z<>0 45 46The TLS/SSL handshake was not successful but was shut down controlled and 47by the specifications of the TLS/SSL protocol. Call SSL_get_error() with the 48return value B<ret> to find out the reason. 49 50=item Z<>1 51 52The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been 53established. 54 55=item E<lt>0 56 57The TLS/SSL handshake was not successful, because a fatal error occurred either 58at the protocol level or a connection failure occurred. The shutdown was 59not clean. It can also occur of action is need to continue the operation 60for non-blocking BIOs. Call SSL_get_error() with the return value B<ret> 61to find out the reason. 62 63=back 64 65=head1 SEE ALSO 66 67L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_accept(3)|SSL_accept(3)>, 68L<SSL_shutdown(3)|SSL_shutdown(3)>, L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>, 69L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>, 70L<SSL_do_handshake(3)|SSL_do_handshake(3)>, 71L<SSL_CTX_new(3)|SSL_CTX_new(3)> 72 73=cut 74