/*
 * Copyright 2010, Haiku, Inc. All Rights Reserved.
 * Distributed under the terms of the MIT License.
 */

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996-1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.	 IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */


#include <net_datalink.h>

#include <ByteOrder.h>
#include <KernelExport.h>
#include <NetUtilities.h>

#include <memory.h>
#include <netinet6/in6.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "ipv6_utils.h"


#define NS_IN6ADDRSZ 16
#define NS_INT16SZ 2

#define SPRINTF(x) ((size_t)sprintf x)


/*!	Convert IPv6 binary address into presentation (printable) format.
	Author: Paul Vixie, 1996.
	\return pointer to dst string if address as been printed
	\return NULL if the buffer is too short
*/
const char *
ip6_sprintf(const in6_addr *srcaddr, char *dst, size_t size)
{
	/*
	 * Note that int32_t and int16_t need only be "at least" large enough
	 * to contain a value of the specified size.  On some systems, like
	 * Crays, there is no such thing as an integer variable with 16 bits.
	 * Keep this in mind if you think this function should have been coded
	 * to use pointer overlays.	 All the world's not a VAX.
	 */
	char tmp[INET6_ADDRSTRLEN], *tp;
	struct { int base, len; } best, cur;
	uint16 words[NS_IN6ADDRSZ / NS_INT16SZ];
	int i;
	const uint8 *src = srcaddr->s6_addr;

	/*
	 * Preprocess:
	 *	Copy the input (bytewise) array into a wordwise array.
	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
	 */
	memset(words, '\0', sizeof words);
	for (i = 0; i < NS_IN6ADDRSZ; i++)
		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
	best.base = -1;
	best.len = 0;
	cur.base = -1;
	cur.len = 0;
	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
		if (words[i] == 0) {
			if (cur.base == -1)
				cur.base = i, cur.len = 1;
			else
				cur.len++;
		} else {
			if (cur.base != -1) {
				if (best.base == -1 || cur.len > best.len)
					best = cur;
				cur.base = -1;
			}
		}
	}
	if (cur.base != -1) {
		if (best.base == -1 || cur.len > best.len)
			best = cur;
	}
	if (best.base != -1 && best.len < 2)
		best.base = -1;

	/*
	 * Format the result.
	 */
	tp = tmp;
	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
		/* Are we inside the best run of 0x00's? */
		if (best.base != -1 && i >= best.base &&
			i < (best.base + best.len)) {
			if (i == best.base)
				*tp++ = ':';
			continue;
		}
		/* Are we following an initial run of 0x00s or any real hex? */
		if (i != 0)
			*tp++ = ':';
		/* Is this address an encapsulated IPv4? */
#if 0
		if (i == 6 && best.base == 0 && (best.len == 6 ||
			(best.len == 7 && words[7] != 0x0001) ||
			(best.len == 5 && words[5] == 0xffff))) {
			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
				return (NULL);
			tp += strlen(tp);
			break;
		}
#endif
		tp += SPRINTF((tp, "%x", words[i]));
	}
	/* Was it a trailing run of 0x00's? */
	if (best.base != -1 && (best.base + best.len) ==
		(NS_IN6ADDRSZ / NS_INT16SZ))
		*tp++ = ':';
	*tp++ = '\0';

	/*
	 * Check for overflow, copy, and we're done.
	 */
	if ((size_t)(tp - tmp) > size)
		return NULL;

	strcpy(dst, tmp);
	return dst;
}