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SSL_COMP_add_compression_method(3)


NAME

  SSL_COMP_add_compression_method - Handle SSL/TLS integrated compression
  methods


SYNOPSIS

  #include <openssl/ssl.h>

  int SSL_COMP_add_compression_method(
	  int id,
	  COMP_METHOD *cm );


DESCRIPTION

  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

  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

  The following return values can occur:

  0	  The operation failed. Check the error queue to learn the reason.

  1	  The operation succeeded.


SEE ALSO

  Functions: ssl(3)

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