NAME
SMIME_read_CMS —
extract CMS ContentInfo from an S/MIME
message
SYNOPSIS
#include
<openssl/cms.h>
CMS_ContentInfo *
SMIME_read_CMS(BIO *in,
BIO **bcont);
DESCRIPTION
SMIME_read_CMS()
parses a message in S/MIME format from in.
If the message uses cleartext signing, the content is saved in a
memory BIO which is written to *bcont and which can
then be passed to
CMS_verify(3) with the CMS_DETACHED
flag set. Otherwise, *bcont is set to
NULL and the type of the returned structure can be
determined using
CMS_get0_type(3).
To support future functionality if bcont is
not NULL, *bcont should be
initialized to NULL, for example:
BIO *cont = NULL; CMS_ContentInfo *cms = SMIME_read_CMS(in, &cont);
RETURN VALUES
SMIME_read_CMS() returns a valid
CMS_ContentInfo structure or
NULL if an error occurred. The error can be obtained
from
ERR_get_error(3).
SEE ALSO
CMS_ContentInfo_new(3), CMS_decrypt(3), CMS_get0_type(3), CMS_verify(3), d2i_CMS_ContentInfo(3), SMIME_read_ASN1(3), SMIME_write_CMS(3)
HISTORY
SMIME_read_CMS() first appeared in OpenSSL
0.9.8h and has been available since OpenBSD 6.7.
BUGS
The MIME parser used by SMIME_read_CMS()
is somewhat primitive. While it will handle most S/MIME messages, more
complex compound formats may not work.
The parser assumes that the CMS_ContentInfo structure is always base64 encoded and will not handle the case where it is in binary format or uses quoted printable format.
The use of a memory BIO to hold the signed content limits the size of the message which can be processed due to memory restraints: a streaming single pass option should be available.