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SSL_COMP_ADD_COMPRESSION_METHOD(3)  OpenSSL SSL_COMP_ADD_COMPRESSION_METHOD(3)

NAME
       SSL_COMP_add_compression_method,	SSL_COMP_get_compression_methods,
       SSL_COMP_get0_name, SSL_COMP_get_id, SSL_COMP_free_compression_methods
       - handle	SSL/TLS	integrated compression methods

SYNOPSIS
	#include <openssl/ssl.h>

	int SSL_COMP_add_compression_method(int	id, COMP_METHOD	*cm);
	STACK_OF(SSL_COMP) *SSL_COMP_get_compression_methods(void);
	const char *SSL_COMP_get0_name(const SSL_COMP *comp);
	int SSL_COMP_get_id(const SSL_COMP *comp);

       Deprecated:

	#if OPENSSL_API_COMPAT < 0x10100000L
	void SSL_COMP_free_compression_methods(void)
	#endif

DESCRIPTION
       SSL_COMP_add_compression_method() adds the compression method cm	with
       the identifier id to the	list of	available compression methods. This
       list is globally	maintained for all SSL operations within this
       application.  It	cannot be set for specific SSL_CTX or SSL objects.

       SSL_COMP_get_compression_methods() returns a stack of all of the
       available compression methods or	NULL on	error.

       SSL_COMP_get0_name() returns the	name of	the compression	method comp.

       SSL_COMP_get_id() returns the id	of the compression method comp.

       SSL_COMP_free_compression_methods() releases any	resources acquired to
       maintain	the internal table of compression methods.

NOTES
       The TLS standard	(or SSLv3) allows the integration of compression
       methods into the	communication. The TLS RFC does	however	not specify
       compression methods or their corresponding identifiers, so there	is
       currently no compatible way to integrate	compression with unknown
       peers. It is therefore currently	not recommended	to integrate
       compression into	applications. Applications for non-public use may
       agree on	certain	compression methods. Using different compression
       methods with the	same identifier	will lead to connection	failure.

       An OpenSSL client speaking a protocol that allows compression (SSLv3,
       TLSv1) will unconditionally send	the list of all	compression methods
       enabled with SSL_COMP_add_compression_method() to the server during the
       handshake.  Unlike the mechanisms to set	a cipher list, there is	no
       method available	to restrict the	list of	compression method on a	per
       connection basis.

       An OpenSSL server will match the	identifiers listed by a	client against
       its own compression methods and will unconditionally activate
       compression when	a matching identifier is found.	There is no way	to
       restrict	the list of compression	methods	supported on a per connection
       basis.

       If enabled during compilation, the OpenSSL library will have the
       COMP_zlib() compression method available.

RETURN VALUES
       SSL_COMP_add_compression_method() may return the	following values:

       0   The operation succeeded.

       1   The operation failed. Check the error queue to find out the reason.

       SSL_COMP_get_compression_methods() returns the stack of compressions
       methods or NULL on error.

       SSL_COMP_get0_name() returns the	name of	the compression	method or NULL
       on error.

       SSL_COMP_get_id() returns the name of the compression method or -1 on
       error.

SEE ALSO
       ssl(7)

HISTORY
       SSL_COMP_free_compression_methods() was deprecated in OpenSSL 1.1.0; do
       not use it.  SSL_COMP_get0_name() and SSL_comp_get_id() were added in
       OpenSSL 1.1.0d.

COPYRIGHT
       Copyright 2001-2016 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
       <https://www.openssl.org/source/license.html>.

1.1.1a				  2018-11-20SSL_COMP_ADD_COMPRESSION_METHOD(3)

NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | SEE ALSO | HISTORY | COPYRIGHT

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