1=pod
2
3=head1 NAME
4
5SSL_write - write bytes to a TLS/SSL connection.
6
7=head1 SYNOPSIS
8

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20If necessary, SSL_write() will negotiate a TLS/SSL session, if
21not already explicitly performed by L<SSL_connect(3)|SSL_connect(3)> or
22L<SSL_accept(3)|SSL_accept(3)>. If the
23peer requests a re-negotiation, it will be performed transparently during
24the SSL_write() operation. The behaviour of SSL_write() depends on the
25underlying BIO.
26
27For the transparent negotiation to succeed, the B<ssl> must have been
28initialized to client or server mode. This is being done by calling
29L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> or SSL_set_accept_state()
30before the first call to an L<SSL_read(3)|SSL_read(3)> or SSL_write() function.
31
32If the underlying BIO is B<blocking>, SSL_write() will only return, once the
33write operation has been finished or an error occurred, except when a
34renegotiation take place, in which case a SSL_ERROR_WANT_READ may occur.
35This behaviour can be controlled with the SSL_MODE_AUTO_RETRY flag of the
36L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)> call.
37
38If the underlying BIO is B<non-blocking>, SSL_write() will also return,

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73
74=item E<gt>0
75
76The write operation was successful, the return value is the number of
77bytes actually written to the TLS/SSL connection.
78
79=item 0
80
81The write operation was not successful. Probably the underlying connection
82was closed. Call SSL_get_error() with the return value B<ret> to find out,
83whether an error occurred or the connection was shut down cleanly
84(SSL_ERROR_ZERO_RETURN).
85
86SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
87only be detected, whether the underlying connection was closed. It cannot
88be checked, why the closure happened.
89
90=item E<lt>0
91
92The write operation was not successful, because either an error occurred
93or action must be taken by the calling process. Call SSL_get_error() with the
94return value B<ret> to find out the reason.
95
96=back
97
98=head1 SEE ALSO
99
100L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_read(3)|SSL_read(3)>,
101L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
102L<SSL_connect(3)|SSL_connect(3)>, L<SSL_accept(3)|SSL_accept(3)>
103L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
104L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
105
106=cut