1=pod
2
3=head1 NAME
4
5SSL_read - read bytes from a TLS/SSL connection.
6
7=head1 SYNOPSIS
8
--- 11 unchanged lines hidden (view full) ---
20If necessary, SSL_read() 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_read() operation. The behaviour of SSL_read() 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 SSL_read() or L<SSL_write(3)|SSL_write(3)>
31function.
32
33SSL_read() works based on the SSL/TLS records. The data are received in
34records (with a maximum record size of 16kB for SSLv3/TLSv1). Only when a
35record has been completely received, it can be processed (decryption and
36check of integrity). Therefore data that was not retrieved at the last
37call of SSL_read() can still be buffered inside the SSL layer and will be
38retrieved on the next call to SSL_read(). If B<num> is higher than the
39number of bytes buffered, SSL_read() will return with the bytes buffered.
--- 38 unchanged lines hidden (view full) ---
78
79=item E<gt>0
80
81The read operation was successful; the return value is the number of
82bytes actually read from the TLS/SSL connection.
83
84=item 0
85
86The read operation was not successful. The reason may either be a clean
87shutdown due to a "close notify" alert sent by the peer (in which case
88the SSL_RECEIVED_SHUTDOWN flag in the ssl shutdown state is set
89(see L<SSL_shutdown(3)|SSL_shutdown(3)>,
90L<SSL_set_shutdown(3)|SSL_set_shutdown(3)>). It is also possible, that
91the peer simply shut down the underlying transport and the shutdown is
92incomplete. Call SSL_get_error() with the return value B<ret> to find out,
93whether an error occurred or the connection was shut down cleanly
94(SSL_ERROR_ZERO_RETURN).
95
96SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
97only be detected, whether the underlying connection was closed. It cannot
98be checked, whether the closure was initiated by the peer or by something
99else.
100
101=item E<lt>0
102
103The read operation was not successful, because either an error occurred
104or action must be taken by the calling process. Call SSL_get_error() with the
105return value B<ret> to find out the reason.
106
107=back
108
109=head1 SEE ALSO
110
111L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_write(3)|SSL_write(3)>,
112L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
113L<SSL_connect(3)|SSL_connect(3)>, L<SSL_accept(3)|SSL_accept(3)>
114L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
115L<SSL_shutdown(3)|SSL_shutdown(3)>, L<SSL_set_shutdown(3)|SSL_set_shutdown(3)>,
116L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
117
118=cut
2
3=head1 NAME
4
5SSL_read - read bytes from a TLS/SSL connection.
6
7=head1 SYNOPSIS
8
--- 11 unchanged lines hidden (view full) ---
20If necessary, SSL_read() 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_read() operation. The behaviour of SSL_read() 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 SSL_read() or L<SSL_write(3)|SSL_write(3)>
31function.
32
33SSL_read() works based on the SSL/TLS records. The data are received in
34records (with a maximum record size of 16kB for SSLv3/TLSv1). Only when a
35record has been completely received, it can be processed (decryption and
36check of integrity). Therefore data that was not retrieved at the last
37call of SSL_read() can still be buffered inside the SSL layer and will be
38retrieved on the next call to SSL_read(). If B<num> is higher than the
39number of bytes buffered, SSL_read() will return with the bytes buffered.
--- 38 unchanged lines hidden (view full) ---
78
79=item E<gt>0
80
81The read operation was successful; the return value is the number of
82bytes actually read from the TLS/SSL connection.
83
84=item 0
85
86The read operation was not successful. The reason may either be a clean
87shutdown due to a "close notify" alert sent by the peer (in which case
88the SSL_RECEIVED_SHUTDOWN flag in the ssl shutdown state is set
89(see L<SSL_shutdown(3)|SSL_shutdown(3)>,
90L<SSL_set_shutdown(3)|SSL_set_shutdown(3)>). It is also possible, that
91the peer simply shut down the underlying transport and the shutdown is
92incomplete. Call SSL_get_error() with the return value B<ret> to find out,
93whether an error occurred or the connection was shut down cleanly
94(SSL_ERROR_ZERO_RETURN).
95
96SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
97only be detected, whether the underlying connection was closed. It cannot
98be checked, whether the closure was initiated by the peer or by something
99else.
100
101=item E<lt>0
102
103The read operation was not successful, because either an error occurred
104or action must be taken by the calling process. Call SSL_get_error() with the
105return value B<ret> to find out the reason.
106
107=back
108
109=head1 SEE ALSO
110
111L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_write(3)|SSL_write(3)>,
112L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
113L<SSL_connect(3)|SSL_connect(3)>, L<SSL_accept(3)|SSL_accept(3)>
114L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
115L<SSL_shutdown(3)|SSL_shutdown(3)>, L<SSL_set_shutdown(3)|SSL_set_shutdown(3)>,
116L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
117
118=cut