Imported OpenSSL 1.1.1a

doc/man3/SSL_CTX_set_mode.pod

@@ -0,0 +1,138 @@
+=pod
+
+=head1 NAME
+
+SSL_CTX_set_mode, SSL_CTX_clear_mode, SSL_set_mode, SSL_clear_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate SSL engine mode
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ long SSL_CTX_set_mode(SSL_CTX *ctx, long mode);
+ long SSL_CTX_clear_mode(SSL_CTX *ctx, long mode);
+ long SSL_set_mode(SSL *ssl, long mode);
+ long SSL_clear_mode(SSL *ssl, long mode);
+
+ long SSL_CTX_get_mode(SSL_CTX *ctx);
+ long SSL_get_mode(SSL *ssl);
+
+=head1 DESCRIPTION
+
+SSL_CTX_set_mode() adds the mode set via bitmask in B<mode> to B<ctx>.
+Options already set before are not cleared.
+SSL_CTX_clear_mode() removes the mode set via bitmask in B<mode> from B<ctx>.
+
+SSL_set_mode() adds the mode set via bitmask in B<mode> to B<ssl>.
+Options already set before are not cleared.
+SSL_clear_mode() removes the mode set via bitmask in B<mode> from B<ssl>.
+
+SSL_CTX_get_mode() returns the mode set for B<ctx>.
+
+SSL_get_mode() returns the mode set for B<ssl>.
+
+=head1 NOTES
+
+The following mode changes are available:
+
+=over 4
+
+=item SSL_MODE_ENABLE_PARTIAL_WRITE
+
+Allow SSL_write_ex(..., n, &r) to return with 0 < r < n (i.e. report success
+when just a single record has been written). This works in a similar way for
+SSL_write(). When not set (the default), SSL_write_ex() or SSL_write() will only
+report success once the complete chunk was written. Once SSL_write_ex() or
+SSL_write() returns successful, B<r> bytes have been written and the next call
+to SSL_write_ex() or SSL_write() must only send the n-r bytes left, imitating
+the behaviour of write().
+
+=item SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER
+
+Make it possible to retry SSL_write_ex() or SSL_write() with changed buffer
+location (the buffer contents must stay the same). This is not the default to
+avoid the misconception that non-blocking SSL_write() behaves like
+non-blocking write().
+
+=item SSL_MODE_AUTO_RETRY
+
+During normal operations, non-application data records might need to be sent or
+received that the application is not aware of.
+If a non-application data record was processed,
+L<SSL_read_ex(3)> and L<SSL_read(3)> can return with a failure and indicate the
+need to retry with B<SSL_ERROR_WANT_READ>.
+If such a non-application data record was processed, the flag
+B<SSL_MODE_AUTO_RETRY> causes it to try to process the next record instead of
+returning.
+
+In a non-blocking environment applications must be prepared to handle
+incomplete read/write operations.
+Setting B<SSL_MODE_AUTO_RETRY> for a non-blocking B<BIO> will process
+non-application data records until either no more data is available or
+an application data record has been processed.
+
+In a blocking environment, applications are not always prepared to
+deal with the functions returning intermediate reports such as retry
+requests, and setting the B<SSL_MODE_AUTO_RETRY> flag will cause the functions
+to only return after successfully processing an application data record or a
+failure.
+
+Turning off B<SSL_MODE_AUTO_RETRY> can be useful with blocking B<BIO>s in case
+they are used in combination with something like select() or poll().
+Otherwise the call to SSL_read() or SSL_read_ex() might hang when a
+non-application record was sent and no application data was sent.
+
+=item SSL_MODE_RELEASE_BUFFERS
+
+When we no longer need a read buffer or a write buffer for a given SSL,
+then release the memory we were using to hold it.
+Using this flag can
+save around 34k per idle SSL connection.
+This flag has no effect on SSL v2 connections, or on DTLS connections.
+
+=item SSL_MODE_SEND_FALLBACK_SCSV
+
+Send TLS_FALLBACK_SCSV in the ClientHello.
+To be set only by applications that reconnect with a downgraded protocol
+version; see draft-ietf-tls-downgrade-scsv-00 for details.
+
+DO NOT ENABLE THIS if your application attempts a normal handshake.
+Only use this in explicit fallback retries, following the guidance
+in draft-ietf-tls-downgrade-scsv-00.
+
+=item SSL_MODE_ASYNC
+
+Enable asynchronous processing. TLS I/O operations may indicate a retry with
+SSL_ERROR_WANT_ASYNC with this mode set if an asynchronous capable engine is
+used to perform cryptographic operations. See L<SSL_get_error(3)>.
+
+=back
+
+All modes are off by default except for SSL_MODE_AUTO_RETRY which is on by
+default since 1.1.1.
+
+=head1 RETURN VALUES
+
+SSL_CTX_set_mode() and SSL_set_mode() return the new mode bitmask
+after adding B<mode>.
+
+SSL_CTX_get_mode() and SSL_get_mode() return the current bitmask.
+
+=head1 SEE ALSO
+
+L<ssl(7)>, L<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_write_ex(3)> or
+L<SSL_write(3)>, L<SSL_get_error(3)>
+
+=head1 HISTORY
+
+SSL_MODE_ASYNC was first added to OpenSSL 1.1.0.
+
+=head1 COPYRIGHT
+
+Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut