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Diffstat (limited to 'crypto/openssl/doc/ssl/SSL_COMP_add_compression_method.pod')
-rw-r--r-- | crypto/openssl/doc/ssl/SSL_COMP_add_compression_method.pod | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/crypto/openssl/doc/ssl/SSL_COMP_add_compression_method.pod b/crypto/openssl/doc/ssl/SSL_COMP_add_compression_method.pod new file mode 100644 index 0000000..2a98739 --- /dev/null +++ b/crypto/openssl/doc/ssl/SSL_COMP_add_compression_method.pod @@ -0,0 +1,70 @@ +=pod + +=head1 NAME + +SSL_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 DESCRIPTION + +SSL_COMP_add_compression_method() adds the compression method B<cm> with +the identifier B<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. + +=head1 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. + +The OpenSSL library has the compression methods B<COMP_rle()> and (when +especially enabled during compilation) B<COMP_zlib()> available. + +=head1 WARNINGS + +Once the identities of the compression methods for the TLS protocol have +been standardized, the compression API will most likely be changed. Using +it in the current state is not recommended. + +=head1 RETURN VALUES + +SSL_COMP_add_compression_method() may return the following values: + +=over 4 + +=item 1 + +The operation succeeded. + +=item 0 + +The operation failed. Check the error queue to find out the reason. + +=back + +=head1 SEE ALSO + +L<ssl(3)|ssl(3)> + +=cut |