=pod=head1 NAMESSL_COMP_add_compression_method - handle SSL/TLS integrated compression methods=head1 SYNOPSIS #include <openssl/ssl.h> int SSL_COMP_add_compression_method(int id, COMP_METHOD *cm);=head1 DESCRIPTIONSSL_COMP_add_compression_method() adds the compression method B<cm> withthe identifier B<id> to the list of available compression methods. Thislist is globally maintained for all SSL operations within this application.It cannot be set for specific SSL_CTX or SSL objects.=head1 NOTESThe TLS standard (or SSLv3) allows the integration of compression methodsinto the communication. The TLS RFC does however not specify compressionmethods or their corresponding identifiers, so there is currently no compatibleway to integrate compression with unknown peers. It is therefore currently notrecommended to integrate compression into applications. Applications fornon-public use may agree on certain compression methods. Using differentcompression 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 withSSL_COMP_add_compression_method() to the server during the handshake.Unlike the mechanisms to set a cipher list, there is no method available torestrict the list of compression method on a per connection basis.An OpenSSL server will match the identifiers listed by a client againstits own compression methods and will unconditionally activate compressionwhen a matching identifier is found. There is no way to restrict the listof compression methods supported on a per connection basis.The OpenSSL library has the compression methods B<COMP_rle()> and (whenespecially enabled during compilation) B<COMP_zlib()> available.=head1 WARNINGSOnce the identities of the compression methods for the TLS protocol havebeen standardized, the compression API will most likely be changed. Usingit in the current state is not recommended.=head1 RETURN VALUESSSL_COMP_add_compression_method() may return the following values:=over 4=item 0The operation succeeded.=item 1The operation failed. Check the error queue to find out the reason.=back=head1 SEE ALSOL<ssl(3)|ssl(3)>=cut