/* $Id: ace.h,v 1.1 2002/01/02 02:46:26 marka Exp $ */
/*
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#ifndef MDN_ACE_H
#define MDN_ACE_H 1

/*
 * ACE converter utility module.
 */

#include <mdn/result.h>

/*
 * ACE identifier type -- prefix or suffix.
 */
enum {
	mdn__ace_prefix,
	mdn__ace_suffix
};

/*
 * ACE encoding/decode procedure.
 *
 * This prototype applies to both encode and decode procedure.  Both
 * of which converts a domain label (i.e. contains no dots) pointed by
 * 'from', whose length is 'fromlen', and stores the result to 'to',
 * whose size is 'tolen'.
 * the ACE string must not have ACE prefix/suffix, as it is automatically
 * handled by 'mdn__ace_convert'.
 */
typedef mdn_result_t (*mdn__ace_proc_t)(const char *from, size_t fromlen,
					char *to, size_t tolen);

/*
 * ACE converter property.
 *
 * 'id_type' shows the type of ACE identifier, which is either
 * 'mdn__ace_prefix' or 'mdn__ace_suffix'.  'id_str' is the ACE
 * identifier itself.  'encoder' and 'decode' are pointers to the
 * encode and decode procedures.
 * Encode procedure converts a domain name label in UTF-8 to
 * ACE-encoded one, and decode procedure converts ACE-encoded label to
 * UTF-8 encoded one.
 */
typedef struct {
	int id_type;			/* mdn__ace_prefix/mdn__ace_suffix */
	const char *id_str;		/* prefix/suffix string */
	mdn__ace_proc_t encoder;	/* encode procedure */
	mdn__ace_proc_t decoder;	/* decode procedure */
} mdn__ace_t;

/*
 * Utility for ACE converter.
 *
 * Convert a domain name given by 'from' and stores the result to
 * 'to', whose length is 'tolen'.  If 'dir' is 'mdn_convert_u2l',
 * 'from' points UTF-8 string which is converted to ACE encoding.  If
 * 'dir' is 'mdn_convert_l2u', 'from' points ACE string which is
 * converted to UTF-8.
 * This function first breaks down the given name into labels,
 * and encode/decode each label.  When encoding, conversion of
 * STD13 conforming labels (i.e. valid ASCII labels) is skipped.
 * When decoding, if the decoding failed but the label is a legitimate
 * ASCII label, those labels are copied verbatim.  To reject illegally
 * encoded labels, the decoding process performs two kinds of checks:
 *  1. check that the decoded string does NOT comform to STD13.
 *  2. try encoding the decoded string, and see if the result matches
 *     to the original string.
 */
extern mdn_result_t
mdn__ace_convert(mdn__ace_t *ctx, mdn_converter_dir_t dir,
		 const char *from, char *to, size_t tolen);

#endif /* MDN_ACE_H */
