SSL_connect.pod revision 76866 
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. In this case a call to SSL_get_error() with the
29return value of SSL_connect() will yield B<SSL_ERROR_WANT_READ> or
30B<SSL_ERROR_WANT_WRITE>. The calling process then must repeat the call after
31taking appropriate action to satisfy the needs of SSL_connect().
32The action depends on the underlying BIO. When using a non-blocking socket,
33nothing is to be done, but select() can be used to check for the required
34condition. When using a buffering BIO, like a BIO pair, data must be written
35into or retrieved out of the BIO before being able to continue.
36
37When using a generic method (see L<SSL_CTX_new(3)|SSL_CTX_new(3)>), it
38is necessary to call L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>
39before calling SSL_connect() to explicitly switch the B<ssl> to client
40mode.
41
42=head1 RETURN VALUES
43
44The following return values can occur:
45
46=over 4
47
48=item 1
49
50The TLS/SSL handshake was successfully completed, a TLS/SSL connection has been
51established.
52
53=item 0
54
55The TLS/SSL handshake was not successful but was shut down controlled and
56by the specifications of the TLS/SSL protocol. Call SSL_get_error() with the
57return value B<ret> to find out the reason.
58
59=item E<lt>0
60
61The TLS/SSL handshake was not successful, because a fatal error occurred either
62at the protocol level or a connection failure occurred. The shutdown was
63not clean. It can also occur of action is need to continue the operation
64for non-blocking BIOs. Call SSL_get_error() with the return value B<ret>
65to find out the reason.
66
67=back
68
69=head1 SEE ALSO
70
71L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_accept(3)|SSL_accept(3)>,
72L<SSL_shutdown(3)|SSL_shutdown(3)>, L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>,
73L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
74L<SSL_CTX_new(3)|SSL_CTX_new(3)>
75
76=cut
77