| descr | A filter descriptor of type smfiDesc describing the filter's
functions.  The structure has the following members: 
struct smfiDesc
{
	char		*xxfi_name;	/* filter name */
	int		xxfi_version;	/* version code -- do not change */
	unsigned long	xxfi_flags;	/* flags */
	/* connection info filter */
	sfsistat	(*xxfi_connect)(SMFICTX *, char *, _SOCK_ADDR *);
	/* SMTP HELO command filter */
	sfsistat	(*xxfi_helo)(SMFICTX *, char *);
	/* envelope sender filter */
	sfsistat	(*xxfi_envfrom)(SMFICTX *, char **);
	/* envelope recipient filter */
	sfsistat	(*xxfi_envrcpt)(SMFICTX *, char **);
	/* header filter */
	sfsistat	(*xxfi_header)(SMFICTX *, char *, char *);
	/* end of header */
	sfsistat	(*xxfi_eoh)(SMFICTX *);
	/* body block */
	sfsistat	(*xxfi_body)(SMFICTX *, unsigned char *, size_t);
	/* end of message */
	sfsistat	(*xxfi_eom)(SMFICTX *);
	/* message aborted */
	sfsistat	(*xxfi_abort)(SMFICTX *);
	/* connection cleanup */
	sfsistat	(*xxfi_close)(SMFICTX *);
};
A NULL value for any callback function indicates that the filter does
not wish to process the given type of information, simply returning
SMFIS_CONTINUE. |