1=pod 2 3=head1 NAME 4 5 BIO_new_CMS - CMS streaming filter BIO 6 7=head1 SYNOPSIS 8 9 #include <openssl/cms.h> 10 11 BIO *BIO_new_CMS(BIO *out, CMS_ContentInfo *cms); 12 13=head1 DESCRIPTION 14 15BIO_new_CMS() returns a streaming filter BIO chain based on B<cms>. The output 16of the filter is written to B<out>. Any data written to the chain is 17automatically translated to a BER format CMS structure of the appropriate type. 18 19=head1 NOTES 20 21The chain returned by this function behaves like a standard filter BIO. It 22supports non blocking I/O. Content is processed and streamed on the fly and not 23all held in memory at once: so it is possible to encode very large structures. 24After all content has been written through the chain BIO_flush() must be called 25to finalise the structure. 26 27The B<CMS_STREAM> flag must be included in the corresponding B<flags> 28parameter of the B<cms> creation function. 29 30If an application wishes to write additional data to B<out> BIOs should be 31removed from the chain using BIO_pop() and freed with BIO_free() until B<out> 32is reached. If no additional data needs to be written BIO_free_all() can be 33called to free up the whole chain. 34 35Any content written through the filter is used verbatim: no canonical 36translation is performed. 37 38It is possible to chain multiple BIOs to, for example, create a triple wrapped 39signed, enveloped, signed structure. In this case it is the applications 40responsibility to set the inner content type of any outer CMS_ContentInfo 41structures. 42 43Large numbers of small writes through the chain should be avoided as this will 44produce an output consisting of lots of OCTET STRING structures. Prepending 45a BIO_f_buffer() buffering BIO will prevent this. 46 47=head1 BUGS 48 49There is currently no corresponding inverse BIO: i.e. one which can decode 50a CMS structure on the fly. 51 52=head1 RETURN VALUES 53 54BIO_new_CMS() returns a BIO chain when successful or NULL if an error 55occurred. The error can be obtained from ERR_get_error(3). 56 57=head1 SEE ALSO 58 59L<ERR_get_error(3)|ERR_get_error(3)>, L<CMS_sign(3)|CMS_sign(3)>, 60L<CMS_encrypt(3)|CMS_encrypt(3)> 61 62=head1 HISTORY 63 64BIO_new_CMS() was added to OpenSSL 1.0.0 65 66=cut 67