More interdependencies with respect to shutdown behaviour.

[openssl.git] / doc / ssl / SSL_read.pod

diff --git a/doc/ssl/SSL_read.pod b/doc/ssl/SSL_read.pod
index cc7aa1a5476639adcfba3ff8623bafcad12b832b..6b47f2fbd1bb95e5834546dc4618bbaacde3f51d 100644 (file)
--- a/doc/ssl/SSL_read.pod
+++ b/doc/ssl/SSL_read.pod
@@ -25,11 +25,10 @@ the SSL_read() operation. The behaviour of SSL_read() depends on the
 underlying BIO. 
 
 For the transparent negotiation to succeed, the B<ssl> must have been
-initialized to client or server mode. This is not the case if a generic
-method is being used (see L<SSL_CTX_new(3)|SSL_CTX_new(3)>, so that
+initialized to client or server mode. This is being done by calling
 L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> or SSL_set_accept_state()
-must be used before the first call to an SSL_read() or
-L<SSL_write(3)|SSL_write(3)> function).
+before the first call to an SSL_read() or L<SSL_write(3)|SSL_write(3)>
+function.
 
 SSL_read() works based on the SSL/TLS records. The data are received in
 records (with a maximum record size of 16kB for SSLv3/TLSv1). Only when a
@@ -84,9 +83,18 @@ bytes actually read from the TLS/SSL connection.
 
 =item 0
 
-The read operation was not successful, probably because no data was
-available. Call SSL_get_error() with the return value B<ret> to find out,
-whether an error occurred.
+The read operation was not successful, the SSL connection was closed by the
+peer by sending a "close notify" alert. The SSL_RECEIVED_SHUTDOWN flag in
+the ssl shutdown state is set (see L<SSL_shutdown(3)|SSL_shutdown(3)>,
+L<SSL_set_shutdown(3)|SSL_set_shutdown(3)>).
+Call SSL_get_error() with the return value B<ret> to find out,
+whether an error occurred or the connection was shut down cleanly
+(SSL_ERROR_ZERO_RETURN).
+
+SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
+only be detected, whether the underlying connection was closed. It cannot
+be checked, whether the closure was initiated by the peer or by something
+else.
 
 =item E<lt>0
 
@@ -102,6 +110,7 @@ L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_write(3)|SSL_write(3)>,
 L<SSL_CTX_set_mode(3)|SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
 L<SSL_connect(3)|SSL_connect(3)>, L<SSL_accept(3)|SSL_accept(3)>
 L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>,
+L<SSL_shutdown(3)|SSL_shutdown(3)>, L<SSL_set_shutdown(3)|SSL_set_shutdown(3)>,
 L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
 
 =cut