doc/man3/SSL_CTX_set_mode.pod - third_party/openssl - Git at Google

 =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 bit-mask in B<mode> to B<ctx>.
 Options already set before are not cleared.
 SSL_CTX_clear_mode() removes the mode set via bit-mask in B<mode> from B<ctx>.

 SSL_set_mode() adds the mode set via bit-mask in B<mode> to B<ssl>.
 Options already set before are not cleared.
 SSL_clear_mode() removes the mode set via bit-mask 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 nonblocking SSL_write() behaves like
 nonblocking 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 nonblocking environment applications must be prepared to handle
 incomplete read/write operations.
 Setting B<SSL_MODE_AUTO_RETRY> for a nonblocking 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)>.

 =item SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG

 Older versions of OpenSSL had a bug in the computation of the label length
 used for computing the endpoint-pair shared secret. The bug was that the
 terminating zero was included in the length of the label. Setting this option
 enables this behaviour to allow interoperability with such broken
 implementations. Please note that setting this option breaks interoperability
 with correct implementations. This option only applies to DTLS over SCTP.

 =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 bit-mask
 after adding B<mode>.

 SSL_CTX_get_mode() and SSL_get_mode() return the current bit-mask.

 =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 added in OpenSSL 1.1.0.

 =head1 COPYRIGHT

 Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.

 Licensed under the Apache License 2.0 (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
	=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 bit-mask in B<mode> to B<ctx>.
	Options already set before are not cleared.
	SSL_CTX_clear_mode() removes the mode set via bit-mask in B<mode> from B<ctx>.

	SSL_set_mode() adds the mode set via bit-mask in B<mode> to B<ssl>.
	Options already set before are not cleared.
	SSL_clear_mode() removes the mode set via bit-mask 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 nonblocking SSL_write() behaves like
	nonblocking 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 nonblocking environment applications must be prepared to handle
	incomplete read/write operations.
	Setting B<SSL_MODE_AUTO_RETRY> for a nonblocking 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)>.

	=item SSL_MODE_DTLS_SCTP_LABEL_LENGTH_BUG

	Older versions of OpenSSL had a bug in the computation of the label length
	used for computing the endpoint-pair shared secret. The bug was that the
	terminating zero was included in the length of the label. Setting this option
	enables this behaviour to allow interoperability with such broken
	implementations. Please note that setting this option breaks interoperability
	with correct implementations. This option only applies to DTLS over SCTP.

	=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 bit-mask
	after adding B<mode>.

	SSL_CTX_get_mode() and SSL_get_mode() return the current bit-mask.

	=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 added in OpenSSL 1.1.0.

	=head1 COPYRIGHT

	Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.

	Licensed under the Apache License 2.0 (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