SSL_COMP_add_compression_methodSSL_COMP_add_compression_method(3)

NAME    [Toc]    [Back]

       SSL_COMP_add_compression_method  -  Handle  SSL/TLS  integrated
 compression methods

SYNOPSIS    [Toc]    [Back]

       #include <openssl/ssl.h>

       int SSL_COMP_add_compression_method(
               int id,
               COMP_METHOD *cm );

DESCRIPTION    [Toc]    [Back]

       The SSL_COMP_add_compression_method()  function  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.

NOTES    [Toc]    [Back]

       The TLS standard (or SSLv3) allows the integration of compression
  methods into the communication. However, the TLS
       RFC does not specify compression methods or  their  corresponding
  identifiers,  so  there is no  compatible way to
       integrate compression with unknown peers. We do not recommend
  integrating  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.

       The OpenSSL library has the compression methods COMP_rle()
       and   (when   especially   enabled   during   compilation)
       COMP_zlib() available.

       Once the identities of the compression methods for the TLS
       protocol  have been standardized, the compression API will
       most likely be changed. We do not recommend  using  it  in
       its current state.

RETURN VALUES    [Toc]    [Back]

       The  following  return  values  can  occur:  The operation
       failed. Check the error queue to learn  the  reason.   The
       operation succeeded.

SEE ALSO    [Toc]    [Back]

       Functions: ssl(3)



                               SSL_COMP_add_compression_method(3)