SSL_write.pod revision 72613 
1=pod
2
3=head1 NAME
4
5SSL_write - write bytes to a TLS/SSL connection.
6
7=head1 SYNOPSIS
8
9 #include <openssl/ssl.h>
10
11 int SSL_write(SSL *ssl, char *buf, int num);
12
13=head1 DESCRIPTION
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15SSL_write() writes B<num> bytes from the buffer B<buf> into the specified
16B<ssl> connection.
17
18=head1 NOTES
19
20If necessary, SSL_write() will negotiate a TLS/SSL session, if
21not already explicitly performed by SSL_connect() or SSL_accept(). If the
22peer requests a re-negotiation, it will be performed transparently during
23the SSL_write() operation. The behaviour of SSL_write() depends on the
24underlying BIO. 
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26If the underlying BIO is B<blocking>, SSL_write() will only return, once the
27write operation has been finished or an error occurred.
28
29If the underlying BIO is B<non-blocking>, SSL_write() will also return,
30when the underlying BIO could not satisfy the needs of SSL_write()
31to continue the operation. In this case a call to SSL_get_error() with the
32return value of SSL_write() will yield B<SSL_ERROR_WANT_READ> or
33B<SSL_ERROR_WANT_WRITE>. As at any time a re-negotiation is possible, a
34call to SSL_write() can also cause read operations! The calling process
35then must repeat the call after taking appropriate action to satisfy the
36needs of SSL_write(). The action depends on the underlying BIO. When using a
37non-blocking socket, nothing is to be done, but select() can be used to check
38for the required condition. When using a buffering BIO, like a BIO pair, data
39must be written into or retrieved out of the BIO before being able to continue.
40
41=head1 WARNING
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43When an SSL_write() operation has to be repeated because of
44B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated
45with the same arguments.
46
47=head1 RETURN VALUES
48
49The following return values can occur:
50
51=over 4
52
53=item E<gt>0
54
55The write operation was successful, the return value is the number of
56bytes actually written to the TLS/SSL connection.
57
58=item 0
59
60The write operation was not successful. Call SSL_get_error() with the return
61value B<ret> to find out, whether an error occurred.
62
63=item E<lt>0
64
65The write operation was not successful, because either an error occurred
66or action must be taken by the calling process. Call SSL_get_error() with the
67return value B<ret> to find out the reason.
68
69=back
70
71=head1 SEE ALSO
72
73L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_read(3)|SSL_read(3)>,
74L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
75
76=cut
77